final report lawn bot

8/10/2019 Final Report Lawn Bot

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Participating M embers:

Corey Kimble

Colleen M organ

Er in RadtkeDavid Smith

Zachary Taylor

EE 481, Senior Design Project

Automated Lawnmower Final

Report



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AbstractThe main objective for the LawnBot group is to design a lawn mower that incorporates all of the features

from various types of lawn mowers, plus more. The group will create a remote control lawn mower that

utilizes each of the benefits, creating a safe, reliable and user friendly lawn mower. The project was done in

two different stages. The first stage the group completed was the Remote Control Lawn Mower. The second

stage of their project was creating an Autonomous Lawn Mower, the LawnBot. The remote control lawn

mower has been designed and built by many engineers throughout the years. There are many variations of

the remote control lawn mower, as people across the nation have attempted to advance the basic lawn

mower by implementing the remote control aspect. The Autonomous Lawn Mower was a lot more difficult to

design and build. By integrating hardware and software, the students found just how much technology can

be used to develop an outstanding project. The group went a step further by creating an even safer version

of the mower. In addition, the autonomous version is also much more convenient for the user.

Introduction

Mowing the lawn with a standard motor powered lawn mower is an inconvenience, and no one takes

pleasure in it. Cutting grass cannot be easily accomplished by elderly, younger, or disabled people. Motor

powered push lawn mowers and riding lawn mowers create noise pollution due to the loud engine, and local

air pollution due to the combustion in the engine. Also, a motor powered engine requires periodic

maintenance such as changing the engine oil. Even though electric lawn mowers are environmentally friendly,

they too can be an inconvenience. Along with motor powered lawn mowers, electric lawn mowers are also

hazardous and cannot be easily used by all. Also, if the electric lawn mower is corded, mowing could prove to

be problematic and dangerous. The self-propelling electric remote control lawn mower is a lawn mower that

has remote control capability. This prototype is robotic user friendly, cost efficient, safe to use, efficient to

use, and environmentally friendly. It can save significantly on labor costs.

Along with the various ages of users, this lawn mower can also be used by people who have disabilities and

are unable to use a regular push, or riding lawn mower. The prototype will also be automatic and will run on a

charged battery with no cords to interfere with operation. This cordless electric lawn mower includes remote

control capability which is less expensive than a robotic lawn mower with sensor capability. This robot lawn

mower design is safe to use. With its remote control capability the lawn mower stays within the boundaries

of the lawn because the user is able to have fun control over the lawn mower with the controller. This

prototype is also environmentally friendly. There is no need for gas, oil, and engine to use this device because

it is electric powered.

The objective of the self-propelling electric remote control lawn mower is to extend the design of currently

used lawn mowers, and to improve the capabilities of standard robotic lawn mowers as well as assuring cost

efficiency. This self-propelling lawn mower design is comprised of remote control and autonomous capability

that is user friendly so most consumers will be able to use this device. It is safe to use, as well as efficient



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because it electric powered and cordless. With these objectives mentioned, the self-propelling electric

robotic lawn mower is environmentally friendly.



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Table of Contents

Abstract ......................................................................................................................................................... 2

Introduction .................................................................................................................................................. 2

Design Achievements .................................................................................................................................... 7

Bumper ................................................................................................................................................. 7

Invisible Fence ........................................................................................................................................... 7

RoboRealm ................................................................................................................................................ 7

Remote Control ......................................................................................................................................... 7

Hardware Design........................................................................................................................................... 7

Various Components................................................................................................................................. 8

Schematics ................................................................................................................................................ 9

Software Design .......................................................................................................................................... 14

Communication Setup ............................................................................................................................ 14

Initialize Variables ................................................................................................................................... 15

Display Drive Motor Values .................................................................................................................... 16

Setup Variable Watch ............................................................................................................................. 16

Button Interface Panels .......................................................................................................................... 16

Setup Test Panel Interface .................................................................................................................. 17

Setup Start/Stop Panel Interface ........................................................................................................ 18

Main Program Script (VBScript) .............................................................................................................. 18

Battery Check ...................................................................................................................................... 18

Start and Stop Interface Script ............................................................................................................ 19

Object/Boundary Detection ................................................................................................................ 19

Backup Sequence ................................................................................................................................ 19



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Rotate Sequence ................................................................................................................................. 19

Continue Mowing Sequence ............................................................................................................... 19

Source Code ................................................................................................................................................ 20

Test Results ................................................................................................................................................. 22

Safety Precautions ...................................................................................................................................... 23

Reflections .................................................................................................................................................. 24

Appendix 1: User Manual ........................................................................................................................... 24

Introduction ............................................................................................................................................ 24

What’s In the Box? .................................................................................................................................. 25

Before You Begin .................................................................................................................................... 25

Fence Installation Procedure .................................................................................................................. 25

Battery Usage .......................................................................................................................................... 25

Getting Started ....................................................................................................................................... 26

How To Mow Your Lawn with the Remote Control ................................................................................ 26

How to Mow Your Lawn Autonomously ................................................................................................. 26

Safety Features ....................................................................................................................................... 27

Safety Precautions .................................................................................................................................. 27

Appendix 2: Maintenance Manual ............................................................................................................. 27

Battery Charge ........................................................................................................................................ 27

Mower Blade ........................................................................................................................................... 27

Motor Driver ........................................................................................................................................... 28

Drive Motors ........................................................................................................................................... 28

Wheel Replacement................................................................................................................................ 28

Wire Connections ................................................................................................................................... 28



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Relays ...................................................................................................................................................... 29

Appendix 3: Original Design Proposal ......................................................................................................... 30

Appendix 4: Summary of Changes from Original ........................................................................................ 30

Invisible Fence ....................................................................................................................................... 171

Battery orientation ............................................................................................................................... 171

Roll-over Accelerometer ....................................................................................................................... 171

Bumper ................................................................................................................................................. 171



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Design Achievements

Bumper

The bumper design combines both safety attributes as well an interfering detection method. The bumper

system is constructed with PVC (polyvinyl chloride) pipe, sheet metal, springs, and push buttons. With asquare design outlining the mower with the PVC pipe, the eight spring loaded limbs are designed to touch

push buttons when compressed by the sheet metal bumper. The sheet metal surrounds the PVC to protect

and cover all four sides of the lawn mower. This design is for the mower to stop, go into reverse, and spin

when the push button is compressed by any of the eight bolts attached to the surrounding PVC internal

bumper.

Invisible FenceThe invisible fence system is one that diversifies this robotic lawn mower from any other project. Using the

magnetic field of a wire entrenched into the ground, a receiver has been integrated into our obstacle

interrupt system to warn the mower of crossing outside of a bounded area. Essentially the same technologyas an electric dog collar, the electrical pulse that is normally sent to a canine does to the laptop perched onto

the mower.

RoboRealmThe RoboRealm code that this group has developed is used to both control the two motors rotating each rear

wheel along with being the central hub for all the obstacle interrupt system signals. While the blade is

running, our program sends signals to the each motor determining the speed and direction of the mower.

Upon hitting an obstacle or crossing the threshold of the invisible fence, a signal is sent to the laptop via USB

and an interrupt variable is sent. A loop in our RoboRealm program goes through a sequence of stopping the

wheels, going into reverse, and spinning away from the obstacle or toward the bounded area.

Remote ControlThe robotic lawn mower was to be designed with the capability of being controlled both using a laptop

running RoboRealm and a remote control. Integrating The Spektrum DX5e remote control and transmitter

was a process that required elegance in the design by using a switch that toggle between remote control or

RoboRealm mode. This remote control can be used to set the direction and speed of the mower. This

addition allows the user both the option for automation and manual controls, which is an essential part of

this design project.

Hardware Design



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Various Components1. Push Mower Body Frame: This was used as the basis of the mower construction. It was modified to handle

the other components of the LawnBot. The group replaced all four original wheels with two caster wheels and

two larger wheels that are motor driven.

2. 24 Volt Battery: The battery acted as a power supply for the LawnBot.

3. Safety Switch: The safety switch toggles the 24 volt battery’s connection on/off to the rest of the circuit.

The positive terminal of the battery is connected to one terminal of the switch while the other terminal is

connected to the main terminal block.

4. Bumper: The physical bumper is made up of an inner square created by PVC pipe. The outside has PVC

pipe with attached sheet metal that is attached to the inner square with PVC pipe loaded by a spring. There is

a bolt through each spring connecting the outside and inside layer of the PVC pipe. The spring allows the

bumper to compress when the mower has contact with an object. The bumper also has bolts through it that

are there to activate the pushbuttons.

5. Push buttons: The pushbuttons are attached to the inner square of the PVC pipe. They are activated when

the bumper is pushed in and the bolts push them. They let the program know when an object has come in

contact with the mower. The push buttons are in series with each other and are connected to a serial cable

that connects them to the computer.

6. Plexiglass: The plexiglass is mounted to the mower’s body frame and allows other components to be

mounted on top of it. It also allows the computer to sit on top of it.

7. Motors: The LawnBot has a total of three motors. The blade mower came attached to the mower’s body

frame. Both of its terminals are attached to a specified slot on the main terminal block. The other two

mowers are used to move the wheels of the mower. They are both attached to the mower’s body frame with

two u-bolts. The terminals for these two motors are attached to the motor driver’s terminals.

8. Motor Driver- the motor driver is connected to the computer with a serial cable. This allows the program

to dictate the movement of the wheel’s motors.

9. Receiver/Antenna: The receiver and antenna allow the LawnBot to receive communication from a remote

control. The receiver is connected to the motor driver so that the wheel’s motors can be manually driven

using the remote control. The receiver is also connected to relay which allows the motor blade to be

controlled through the remote control.

10. Relay switches: There are two relay switches. The first, a remote control relay, is attached directly to the

receiver and can be switched when toggled by the remote control. The second relay is connected to the first

and when “switched” allows the connect 24 volt battery to power the motor blade. Together the two relay

switches allow the user to activate the mower’s blade using a toggle switch on the remote control.



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11. Computer: The computer stores the program and communicates to various equipment on the LawnBot.

It receives input from the push buttons on the bumper system as well as input from the dog fence receiver.

The computer sends output to the all three motors which allows the LawnBot to move and to mow.

12. Invisible fence receiver, transmitter, and wire: The dog fence receiver sends an output to the computerprogram when the mower approaches the dog fence wire. It is connected to the computer with a serial cable.

The schematics page should be referenced for a better understanding of how the components are electrically

connected.

Schematics

Figure 1: Final Schematic



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Figure 2: Motor Driver Schematic



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Figure 3: Motor Power Schematic



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Figure 4: Receiver Schematic



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Figure 5: Relays Schematic



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Software Design

Communication SetupThe first two processes that the program runs is the initialization of the two communication cables. The first

cable to be initialized is the serial communication cable. The program RoboRealm already had a feature setupcalled “Serial” that created and initialization interface and also governed what went was read in over the

cable and what the program would store that as.

Figure 6: Serial Communication Setup in RoboRealm

The figure seen above is what is used to initialize this connection. When the program is started, the

designated communication port is searched for. Once the port is located, the program initializes module

settings (allowing information to communicate from the cable to the program) and will state if the cable is

connected or not connected. It is from this communication cable that the object avoidance/boundary

detection sensors are f ed into. The variable used for object/boundary detection was “k”.

The second cable to be initialized is the communication cable that controls the mower drive motors. Just like

the “Serial” connection, RoboRealm also had and initialization setup specifically for the motor driver our team

had selected. No programming had to be done to initialize the connection between the computer and the

driver motors. The setup provided searched and found that there were two motors connected to the motor

driver and setup a range of values for the motors to operate under. The setup also allowed for each motor tobe named a variable to be called later on in the program.



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Figure 7: DE Sabertooth Setup in RoboRealm

From the setup, the left drive motor was labeled “Left_Motor” and the right drive motor was labeled

“Right_Motor”. The setup also initialized the value range of the motors to 1-255. For our purposes, 1 is full

power in the forward direction and 255 is full power in the reverse direction. The value 128 (Midway

between 1 and 255) is the value responsible for stopping the motor.

Initialize VariablesThe first set of variables to be initialized are the left and right drive motors. The values of these motors are set

to the stop value (128) which is then processed by the DE_Sabertooth module in RoboRealm and

automatically sets the motor values on program startup.

The second set of variables to be initialized are the count and state variables used throughout the program.

The variable “c” is used as a count variable. It is initialized on startup to a value of zero to begin all counting

sequences at zero. This initialization has to be done on startup because the program might have a previous

value of “c” stored in its memory, which would throw mowing timing sequences off and could cause a safety

hazard.

The next two variables to be initialized are state variables. The variable “p” is used for the button interface

protocol that pops up when the program is opened. This variable is set to a value of two initially. Thereasoning behind this is that a “p” value of 2 is not used in the program so an initial state of the start and stop

buttons is not defined. When either start or stop is selected from the button interface, the value of “p” is

changed and a script program executes the necessary actions. The last initialized variable is the variable “k”.

The variable “k” is used for the object/boundary detection feature of the program. After hours of reviewing

input data when either an object has made contact with the mower, or when the mower gets close to the



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invisible fence, it was determined that “groups” of random values were sent to the computer. Because of the

randomness of the inputs, an arbitrary value of five was assigned to the variable “k” initially.

Display Drive Motor Values

The drive motor values were setup under the “Display_Variable” feature in RoboRealm. These values aredisplayed because the state in which the drive motors are in determines the overall direction in which the

lawn mower moves. This display of variables not only helps the user tell which direction the mower should be

moving in, but it also helps for troubleshooting purposes as well.

Setup Variable Watch“Watch_Variables” is a feature in RoboRealm that pops up a window that displays all of the values current

being used and the variables that have been initialized at some point in the program. This window constantly

updates the value of all the variables. This was a very useful tool when creating the program and is a very

helpful aid when it comes to troubleshooting.

Button Interface Panels

Figure 8: Button Configurator

Using the button configurator, two button panel interfaces were created (A test panel and a main start/stop

panel). Within the button configurator; the name of the button being create, the color of the button, the

color of the text, the position of the button, the size of the button, the variable the button is controlling, the



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value the button with assign to the desired variable, the size of the interface panel, and whether or not the

interface panel pops up when the program is opened can all be edited from this one window.

Setup Test Panel Interface

Figure 9: Test Panel Interface

This test panel was initially created for the help in creating the program and troubleshooting. This panel was

left in the final program because of the troubleshooting ability it has. This panel does not pop up when the

program is opened; it was created for sole troubleshooting purposes.

At the top of the interface, there are four buttons. These buttons all are used for setting certain states to the

main variables used in the program. The “c Reset” button resets the value of the c variable to a value of zero.

This proved useful when determining how many seconds elapsed when c reached a certain value. The “k

Reset” button was used to simulate receiving an object/boundary detection signal. Because during the testing

of the program, the mower was not available at all times (nor was it necessary to have the drive motors

continuously running during the tests), the “k Reset” button allowed for the test of the object/boundary

detection scripts without the need of being connected to the mower. The “j Set” and “j Reset” buttons allow

for state in which the object/boundary detection process is currently in to be changed. This helped out

tremendously when troubleshooting the main code for this project.

The remaining six buttons are for control of the drive motors. The three buttons on the left control the left

drive motor and the three buttons on the right control the right drive motor. The top buttons allow for themotors to be set in the forward state “1”. The middle buttons allow for the motors to be stopped “128”. And

the last buttons allow for the motors to be set in the reverse state “255”. This part of the panel came to great

use when the drive motors were installed and were being tested with the program for the first time. These

buttons were left in the program after the motors had been fully tested because of the secondary use. These

buttons allow for a user to hold the computer and drive the mower solely from the computer. This allows an



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individual to drive the mower back to their garage per say after the mower is done mowing without having to

switch to the remote control mode or carrying the mower.

Setup Start/Stop Panel Interface

Figure 10: Start/Stop Panel Interface

This panel interface is much simpler than the test panel previously discussed. The purpose of this panel is to

be the main interface tool for the project. This panel pops up in the middle of the screen as soon as the

program is opened. The user is to simply hit the start button and the mowing process will commence and the

program will do all of the work. The stop button was added for the sake of a way to stop the mowing process

when needed (The mower is not very fast and easy to access even during the mowing process).

The start button simple sets both of the drive motors to their forward value “1” and the stop button sets both

drive motors to their stopped value “128”.

Main Program Script (VBScript)RoboRealm continuously loops through itself. Because of this, the main processes of this program had to be

broken up into individual scripts in order for them to be executed properly. For the actions needed to be

performed by the mower for this project, there were six main script programs that needed to be created.

Battery Check

The battery check program checks the percent of battery that the computer has left. If the computer were to

run out of power before the mower was done, the mower would continue mowing on a straight path becausethe object/boundary detection systems would not be able to be recognized. This would probably not only

cause damage to the mower itself, but cause damage to others property and bring harm towards any

individual caught in its path. To combat this issue, if the battery power is less than 10%, the drive motors are

set to their stopped state. This will allow for the mower to be approached safely and for the computer to be

detached and charged.



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Start and Stop Interface Script

This script is for the “Start/Stop Interface Panel”. Because a button can only control one variable at a time,

there was the need to control both drive motors simultaneously. In order to do this, the variable “p” wasused. When the start or stop button is pressed on the panel, the value of “p” is changed. This script then

determines whether the start or stop button was pressed. If start was pressed, both drive motors are set to

the forward state “1”. If stop was pressed, both drive motors are set to the stop state “128”. The value of p

then has to be reset at the end of the script in order to prevent an endless loop from occurring.

Object/Boundary Detection

This script is the most important and surprisingly the smallest part of the entire program. The program has to

read in the value received from the input serial connection (Which is the value received from the bumper

switches and the invisible fence shock collar) and store it into a variable, “k”. That variable then has to be

checked for any change. Once that variable has changed, the drive motors are stopped and the next state of

the object/boundary detection is set. The variable “k” is then reset to its normal state so that any other

change can be detected.

Backup Sequence

The count variable and the state variable are read into the script and stored in respective spaces. The backup

sequence is only executed if the correct state value is set from the previous set of code. If the correct state is

set, then the count variable is incremented until a designated value is reached. Once the designated value is

reached (Creating a time delay feature), the drive motors are switched from their stopped positions to

reverse positions. The motors will remain in this state until the next sequence of code is analyzed. After the

drive motors are set to reverse, the state variable is changed so the next task can be executed and the count

variable is reset to zero.

Rotate Sequence

Just like the backup sequence, the count and state variable are read into the script and stored. If the correct

state is present, then the count variable is incremented again until its designated value. The confusing aspect

of this whole process is that the length in which the drive motors remain in a certain state are based off of the

following sequence (I.E. The motors are stopped for as long as the time delay located in the backup sequence

is. The drive motors are in reverse for the length of the time delay designated in this sequence, etc…). Once

the designated count value is reached, the left drive motor is set to remain in reverse and the right drive

motor is set to the forward state. This will cause the mower to perform a zero turn (Pivot based off the center

of the mower), rotating away from the object/boundary the mower just encountered. The state variable ischanged to perform the next task and the count variable is reset to zero.

Continue Mowing Sequence

Finally, the count and state variables are read into the script and stored. If the correct state is present, the

time delay count variable is incremented until the designated value is reached. Both drive motors are then set



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to their forward states so that the mower can continue mowing in a different direction. The state variable is

reset to zero as well as the count variable.

Source CodeInitialize Variables

Set Left_Motor = 128 %Initializes the left drive motor to 128 (Stopped)

Set Right_Motor = 128 %Initializes the right drive motor to 128 (Stopped)

Set p = 2 % The value p is used to start and stop the motors through the Start Stop Interface

Set k = 5 % The value k is used as the variable which object/boundary detection is determined

Set c = 0 %The value c is used as a count variable

Check Battery Power

W = GetVariable("POWER_LIFE_PERCENT") %Stores the value of the computer battery power

if W<10 then %Creates “If -Then” Statement to check if battery power is less than 10%

SetVariable "Right_Motor", 128 %If the battery power is less than 10% set right drive motor to stop

SetVariable "Left_Motor", 128 %If the battery power is less than 10% set left drive motor to stop

end if

Start and Stop Button Interface

p = GetVariable("p") %Retrieves and stores the value of p

if p = 1 Then % “If -Then” Statement checking the value of p

SetVariable "Left_Motor", 1 %If p is equal to 1 then set left drive motor to forward

SetVariable "Right_Motor", 1 %If p is equal to 1 then set right drive motor to forward

end if

if p = 0 Then % “If -Then” Statement checking the value of p

SetVariable "Left_Motor", 128 %If p is equal to 0 then set left drive motor to stop

SetVariable "Right_Motor", 128 %If p is equal to 0 then set left drive motor to stop

end if

SetVariable "p", 2 %Resets the value of p to 2 so a never ending loop is not created

Object/Boundary Detection

k = GetVariable("k") %Retrieves and stores value received from bumper or invisible fence sensor

if k <> 5 then %Checks to see if k is not equal to 5

SetVariable "Left_Motor", 128 % If k is not equal to 5 then set left drive motor to stop



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SetVariable "Right_Motor", 128 % If k is not equal to 5 then set right drive motor to stop

SetVariable "j",3 %Set state variable j to 3

end if

SetVariable "k", 5 % Resets the value of k to 5 so a never ending loop is not created

Backup Sequence

c = GetVariable("c") %Retrieves and stores the value of c

h = GetVariable("h") %Retrieves and stores the value of h

j = GetVariable("j") %Retrieves and stores the value of j

if j = 3 then %Checks to see if the state of j is equal to 3

h = c + 1 %Increments the count variable by one and stores the value in h

SetVariable "c", h %Sets the value of c to the value stored in h

if c = 50 then %Checks to see if c is equal to 50

SetVariable "Left_Motor", 255 %Sets left drive motor to reverse

SetVariable "Right_Motor", 255 %Sets right drive motor to reverse

SetVariable "j", 4 %Sets state variable j to 4

SetVariable "c", 0 %Sets count variable c to 0

end if

end if

Rotate Sequence








SetVariable "Left_Motor", 255 %Sets left drive motor to reverse

SetVariable "Right_Motor", 1 %Sets right drive motor to forward



end if

end if

Continue Mowing Sequence






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SetVariable "Left_Motor", 1 %Sets left drive motor to forward

SetVariable "Right_Motor", 1 %Sets right drive motor to forward



end if

end if

Test Results

The LawnBot was tested in two different environments, indoors and outdoors. The LawnBot was first andmostly tested indoors with the remote control components. The testing occurred throughout the

construction process. As a new component was added to the system it was tested independently to make

sure it worked as desired as well as working in the system as a whole. The motors, relay, computer, and

software were all tested separately as each component was added until each component was working

properly. The group was very successful during this first stage of the LawnBot testing with only a few minor

negative tests. One such occurrence was with the first relay switch. The switch was designed specifically for

use of remote control but was not rated for a high current. When tested, the group found the current the

blade motor drew was not over the rated current, however when first started the blade motor drew a current

which burned out the relay after a few uses. To address this issue, the group added a second relay, which was

not specifically designed for remote control use but could handle a much larger current than the first relay.

The first relay would still be required to be used but would not draw the current from the battery, only

activate the second relay which then allowed the blade motor to operate at the current it needed to start.

This was successfully tested indoors as one could hear the relays activate when the toggle switch was

engaged on the remote control, without having the blade motor connected to the relay for indoor safety

precautions.

The group then attempted testing in an outdoor environment with the remote control to ensure that the

LawnBot was able to cut grass. The group was eventually successful, but it required more effort mechanically

to complete this stage to address issues such as environmental inclines. The group was able to cut the grass

successfully outdoors with the remote control after the changes were made.

The second stage of the testing involved controlling the mower autonomously indoors and outdoors. By

doing so, the group used the program RoboRealm to communicate with the integrated mowing system.

Along with this program, the group used an invisible fence for boundary detection, and a bumper system for

object interference detection. When the LawnBot was tested indoors autonomously with the invisible fence,



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the group was successful. However, the group came across several difficulties that were mostly program

related at this stage. After configuring the program to work well with the invisible fence and the bumper

system’s push buttons, the mower appeared to run smoothly indoors.

Once the LawnBot was tested successfully indoors, the group tested the LawnBot outdoors. The group cameacross several difficulties that were not issues indoors. First, the bumper system fell apart within the first

twenty minutes of use. Unfortunately, this was not a quick fix for the bumper team. The group needed to

reconstruct a more stable bumper that would cooperate in West Virginia’s uneven terrain. With higher

patches of grass, the caster wheels bogged down. When the mower was at a level surface, it cooperated

perfectly. Because of the high torque motors, the LawnBot operated at the same speed no matter the incline.

Additionally, another issue occurred when the remote control receiver and the cables connecting to the

computer were both connected to the motor driver. Both were successful during testing when connected

independently, but having both connected simultaneously, caused communication issues. A switch was

added to toggle back and forth between the remote control and computer. Another issue that occurred

when testing was only having one serial cable for the push buttons and invisible fence. The push buttons andinvisible fence could be read into the program, but the motors could not be controlled at the same time. To

fix this, the group added a second serial cable, which allowed both the buttons and invisible fence to be

connected simultaneously.

As previously mentioned, with time the LawnBot proved to be successful with remote control capability

indoors and outdoors. The LawnBot also proved to be successful autonomously indoors and outdoors.

However, the LawnBot acted more temperamental during autonomous use especially when used outdoors in

less controlled environments.

Safety PrecautionsSafety is a primary concern for the robotic lawn mower. The mower has two different types of kill switches

that play an important role in the safety aspect of the mower. The first is a mower blade kill switch which is

located on the remote control to stop the blade. This switch is a user operated switch and could be used in

the event of an emergency situation. There also is a manual kill switch that is located on the mower to turn

off the mower for storage. Lastly, a bumper was constructed onto the mower which detects when there is a

foreign object in the mower’s path.

With these safety features, users still must take precautions when using this lawn mower. The lawn mower

has a sharp blade that should not be operated by children. Users should remove any objects from the lawn

that may cause interference to the mower before use. Users should not use this lawn mower around pets or

children. Users should not operate electric lawn mower in standing water or during inclement weather. The

lawn mower should only be used on a grassy area. Users should take precautions when installing invisible

fence. Do not operate lawn mower unsupervised.



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Future builders must take precaution when assembling mower. Blades are sharp and could cause harm to

assemblers. The sheet metal bumper has sharp edges and could cause injury. Also, future builders should be

sure to disconnect the mower from the voltage source when wiring.

ReflectionsOverall, constructing the lawn mower was a success. However, there were a few details that were not

constructed that had been originally planned. In addition, there were things that would have been changed

from the beginning that would have made this project much easier. First, the group consisted of five

electrical engineering students. The group should have had a few electrical engineering students, a few

computer science students, and a computer engineering student. The electrical engineering students could

have focused solely on the hardware. The computer science students would have had a lot more experience

with programming and would have been able to develop the software design in a more efficient way. Lastly,

the computer engineering major would have been able to integrate the software and hardware in a much

easier manner.

Secondly, the group also felt that RoboRealm was not the best choice of software for the LawnBot.

RoboRealm is used mainly for digital image processing purposes. The LawnBot group used this software

solely for providing outputs given the inputs. The signal would communicate with the lawn mower after the

mower had come into contact with the invisible fence. Nothing with the RoboRealm software was used for

image analysis. The group would have found a different programming language that was less complex

considering there were only a few input commands.

Lastly, given the amount of money that was provided, the mower was not constructed as well as it could have

been. The group was not able to obtain higher quality power tools than the tools that were used. If better

constructing equipment was supplied to the group, the mower would have cosmetically appeared more

professionally constructed. For instance, the group had a difficult time properly cutting the PVC pipe to the

accurate measurements. Also, if more money had been provided to the group, a Global Positioning System

(GPS) could have been used for the boundary detection instead of the invisible fence. This system is more

accurate than the invisible fence. If the GPS system was installed and used correctly, it would have been

more successful in the boundary detection area. The invisible fence’s program became a tedious process to

complete, and the fence overall was temperamental. In addition, had the GPS been provided, the lawn itself

would have cosmetically appeared much better after a fresh cut.

Appendix 1: User Manual

IntroductionNo one wants their lawn mower to stray into a neighbor's yard, in the street, or even into a flower bed. In

visible fence gives your lawn mower freedom to roam within set boundaries and gives you peace of mind.



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What’s In the Box?The materials that are located in the package are the LawnBot, 24V DC battery, battery charger, remote

control, and invisible fence.

Before You BeginPlot your yard on a piece of paper and draw in the area you want to cover. In several instances corners must

be rounded. The wire forming the fence boundary must make a continuous loop back to the transmitter. The

invisible fence must be buried 1 inch to 3 inches underground. Test your wires aboveground before burying

them.

Precautions when installing Invisible Fence

Be sure to burry fence with care. Invisible fence should not be buried with electrical wires, telephone

wires, television cables, antenna wires or near satellite dishes. Avoid crossing power lines.

If you plan to cross a gravel or dirt driveway, protect your wire by running it through polyvinyl

chloride (PVC) pipe.

Avoid running the boundary wire close to chain-link fences.

Fence Installation Procedure

Step 1:

Referring to the plot you created, lay the wire along your proposed boundary.

Step 2:

Connect the ends of the boundary wires to the transmitter, and turn the system on.

Step 3:

Test the transmitter on the LawnBot to ensure it's working properly. The LawnBot should emit an audible

alert as you near the boundary.

Step 4:

Begin cutting a trench 1 inch to 3 inches deep along your previously planned boundary. Lay the invisible fence

in the trench and burry it.

Battery UsageBe sure to charge 24V battery with the battery charger for 24 hours before installing in the LawnBot.



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Getting Started

Figure 11: Remote Control

Once battery is charged, insert it into the LawnBot. Turn the On/Off switch to the On position to ensure that

the LawnBot is powered.

How To Mow Your Lawn with the Remote ControlWhile the LawnBot is turned Off set the dip switch to the remote control position. Turn ground switch into

remote control position. Turn the On/Off switch in the On position on the Lawn Bot. Place LawnBot within the

area you wish to mow. Turn the On/Off switch on the remote control in the On position. The blade activation

switch must be engaged while using the right wheel and left wheel switch. You may now start mowing the

lawn using the remote control. When finished turn both switches in the Off position.

How to Mow Your Lawn AutonomouslyWhile the LawnBot is turned Off set the dip switch to the autonomous position. Turn ground switch into

autonomous position. Turn the On/Off switch in the On position on the Lawn Bot. Place LawnBot within the

boundaries of the invisible fence. Press “start” on the computer program. Now allow LawnBot to mow the

designated area. The battery has 60 minutes of power usage. When battery is dead, the LawnBot will come

On/Off Switch

Blade Activation Switch

Left Wheel

Right Wheel



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to a complete stop. If your lawn is not completely mowed, recharge the battery, until it is completely charged,

and repeat the mowing process.

Safety Features

The mower has two different types of On/Off switches that play an important role in the safety aspect of themower. The first is a mower blade On/Off switch which is located on the remote control to stop the blade.

This switch is a user operated switch and could be used in the event of an emergency situation. There also is

an On/Off switch that is located on the mower. Lastly, a bumper was constructed onto the mower which

detects when there is a foreign object in the mower’s path. When the bumper comes in contact with a foreign

object, when in autonomous mode, the LawnBot with stop and reroute itself.

Safety Precautions- Warning! The lawn mower has a sharp blade and could cause injury.

- The LawnBot should not be operated by children.

- Be sure to remove any objects from the lawn that may cause interference to the mower before use.

- Do not use this lawn mower around pets or children.

- Do not operate electric lawn mower in standing water or during inclement weather.

- Only use LawnBot on a grass.

- Do not operate lawn mower unsupervised.

- Do not attempt to turn the LawnBot off while it is in the autonomous mode.

Appendix 2: Maintenance ManualThis manual is for the upkeep and reference manual for the robotic lawn mower. Within this manual, simple

part fixes will be discussed as well as routine mower maintenance.

Battery ChargeThe entire mower relies on the battery being charged. There is a battery gauge located on top of the battery

itself. Three lights means that the battery is fully charged, two lights means there is at least half the battery

left, and one light means that the batter is low and needs recharged. The mower should not be operated if

the battery is lower than two lights of charge. The battery should be charged every time before each time the

mower is to be used, using the provided charging cable. If the

Mower BladeThe blade located on this mower is like the blade on any regular lawn mower. This mower will accept any

regular 14” (14 inch) mower blade. Here are a few steps to check on the sharpness of the mower blade:

• Ensure that the mower is turned off and remove the battery

• Tilt the lawn mower on its side to reveal the undercarriage of the mower

• Loosen nut holding blade in place and remove blade



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• Inspect the sharpness of blade (Doesn’t need to be razor sharp but still needs an edge)

• If blade is dull, either buy new blade or sharpen the old blade

• Replace blade and tighten nut

• Place mower upright and re-insert battery

Motor DriverThe motor driver is a self-contained unit that controls the voltage provided to the drive motors. When the

power for the mower is on, there should be one dim blue light on the motor driver. Any errors or issues with

the motor driver will result in a flashing red light or a no light at all. In either case, first check all connections

leading to the motor driver and tighten any loose connections. If this does not fix the error please contact the

following:

Email: [email protected]

Phone: (330) 634-1430

Fax: (330) 634-0215

Hours: 9AM to 7PM Eastern Time

Mail: Dimension Engineering

899 Moe Drive #21

Akron, OH 44310

Drive MotorsSince these are electric motors, they require no routine maintenance.

If the drive motors are not working properly, first check the motor connections. If that is not the problem

check the connection between the remote control and the receiver or the communication connectionbetween the computer and the motor driver. If there is no connection issue, ensure that the battery is fully

charged. If the motors still do not respond, they will need to be replaced.

http://www.phidgets.com/products.php?category=24&product_id=3273_0

Wheel ReplacementThe front wheels are simple 2” (2 inch) caster wheels that can be purchased at any hardware store if the

wheels are damaged or just need replaced. The larger rear wheels are located at the following address:

http://www.andymark.com/product-p/am-0514.htm. If a back wheel needs replace (broken spokes or hub),

remove the cotter key from the hub, slide old wheel off, slide new wheel on and replace cotter key. If the

tread is low on the tires, new tread can also be purchased from andymark and instructions for installation will

be included

Wire ConnectionsAny wire connection that deals with a motor or 24v power is 12 AWG wire. Any wire connection that deals

with communication is 20 AWG wire. If any wire appears to be damaged, replace entire wire.



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RelaysIf the mower blade will not spin, it is most likely a relay issue. Listen to each relay when they are energized to

hear a “click”. If there is no “click” then the relay is either bad or there is a loose connection. Check the

connections going to and from the relays. If this does not fix the issue then the bad relay(s) will need to be

replaced. The large relay can be replaced with any 24v ice cube relay that can withstand anything over 10

amps. The smaller relay will need to be replaced with another Dimension Engineering Battle Switch:

http://www.dimensionengineering.com/products/battleswitch.



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Appendix 3: Original Design Proposal

Design

Proposal for the LawnBot Changing the way you mow your grass since 2012.

Participating Members:

Corey Kimble

Colleen Morgan

Erin RadtkeDavid Smith

Zachary Taylor



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April 2012



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Contents

1. Extended Problem Statement ............................................................................................................ 38

1.1. Need ........................................................................................................................................... 38

1.2. Objective .................................................................................................................................... 39

1.3. Background ................................................................................................................................ 40

1.4. Stakeholder goals ....................................................................................................................... 42

1.5. Objective Tree ............................................................................................................................ 43

1.6. Ranking of Needs ....................................................................................................................... 43

2. Requirements Specification ............................................................................................................... 45

2.1. Function Descriptions ................................................................................................................ 45

2.1.1. Added Component Functions ............................................................................................ 45

2.1.1.1. Rechargeable Batteries for Added Components............................................................ 45

2.1.1.2. Deadman’s Killswitch ..................................................................................................... 45

2.1.1.3. Turn Over Killswitch ....................................................................................................... 45

2.1.1.4. Sensor ............................................................................................................................ 45

2.1.1.5. Zero Turn Function ......................................................................................................... 46

2.1.1.6. Grass Clipping Catcher ................................................................................................... 46

2.1.2. 2. Remote Control Functions ............................................................................................. 46

2.1.2.1. Remote Control/Transmitter ......................................................................................... 46

2.1.2.2. Remote Engagement...................................................................................................... 46



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2.1.2.3. Receiver .......................................................................................................................... 46

2.1.3. Mower Functions ............................................................................................................... 47

2.1.3.1. Mowing Ability ............................................................................................................... 47

2.1.3.2. Self-Propulsion ............................................................................................................... 47

2.1.3.3. Electric Mower ............................................................................................................... 47

2.1.4. Automation Functions ........................................................................................................ 47

2.1.4.1. Self-Controlled ............................................................................................................... 47

2.1.4.2. Battery Detection ........................................................................................................... 47

2.1.4.3. Boundary Detection ....................................................................................................... 48

2.2. Requirements ......................................................................................................................... 48

2.2.1. Marketing Requirements ................................................................................................... 48

2.2.2. Engineering Requirements ................................................................................................. 49

2.2.3. Market / Engineering Requirement Trade-off ............................................................... 50

2.3. Competitive Benchmarks ........................................................................................................... 51

2.3.1. Constraints ......................................................................................................................... 51

2.3.1.1. Economic ........................................................................................................................ 51

2.3.1.2. Environmental ................................................................................................................ 51

2.3.1.3. Ethical and Legal ............................................................................................................ 52

2.3.1.4. Health and Safety ........................................................................................................... 52

2.3.1.5. Manufacturability ........................................................................................................... 52



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2.3.1.6. Political ........................................................................................................................... 52

2.3.1.7. Social .............................................................................................................................. 52

2.3.1.8. Sustainability .................................................................................................................. 53

2.3.2. Standards ........................................................................................................................... 53

2.3.2.1. Safety ............................................................................................................................. 53

2.3.2.2. Data Formats .................................................................................................................. 53

2.3.2.3. Programming Languages ................................................................................................ 53

2.3.2.4. Meta-Standards ............................................................................................................. 54

3. System Design .................................................................................................................................... 55

3.1. Scope .......................................................................................................................................... 55

3.2. Context Diagram ........................................................................................................................ 56

3.3. First Stage: Remote Control ....................................................................................................... 57

3.3.1. Basic Operations ................................................................................................................ 57

3.3.1.1. Electric Lawn Mower Base ............................................................................................. 57

3.3.1.2. Remote Control Transmitter and Receiver .................................................................... 57

3.3.1.3. Motor Driver .................................................................................................................. 58

3.3.1.4. Rear Motors ................................................................................................................... 58

3.3.1.5. Caster Wheels ................................................................................................................ 58

3.3.1.6. Miscellaneous ................................................................................................................ 58

3.3.1. Wiring Diagram .................................................................................................................. 59

3.3.2. Remote Control Interface .................................................................................................. 60



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3.3.2.1. Kill Switch ....................................................................................................................... 60

3.3.2.2. Left Motor Control ......................................................................................................... 60

3.3.2.3. Right Motor Control ....................................................................................................... 61

3.3.3. Functions of Overall Operation .......................................................................................... 61

3.3.4. Testing ................................................................................................................................ 62

3.4. Second Stage: Automation......................................................................................................... 63

3.4.1. Basic Operations ................................................................................................................ 63

3.4.2. Sensors ............................................................................................................................... 63

3.4.2.1. Tilt Sensor ....................................................................................................................... 63

3.4.2.2. Object Avoidance ........................................................................................................... 64

3.4.2.3. Range Sensor .................................................................................................................. 64

3.4.3. Processor ............................................................................................................................ 64

3.4.4. Computer ........................................................................................................................... 65

3.4.5. Programming...................................................................................................................... 65

3.4.5.1. RoboRealm ..................................................................................................................... 65

3.4.5.2. Dog Fence Boundary ...................................................................................................... 66

3.4.5.3. GPS Boundary ................................................................................................................. 66

3.4.5.4. Trace and Record Boundary ........................................................................................... 67

3.4.6. Testing ................................................................................................................................ 68

4. SOFTWARE TESTS ............................................................................................................................... 69

4.1. Remote Control – Transmitter Signal......................................................................................... 69



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4.2. Mower Orientation .................................................................................................................... 69

4.3. Battery Power ............................................................................................................................ 70

4.4. Obstacle Sensor ......................................................................................................................... 71

4.5. Active Blade ............................................................................................................................... 72

4.6. Mobility ...................................................................................................................................... 75

4.7. Direction of Motion ................................................................................................................... 78

5. Project Plan ........................................................................................................................................ 81

5.1. Project Management ................................................................................................................. 81

5.1.1. Preliminary Work Breakdown ............................................................................................ 81

5.1.2. Project Timelines................................................................................................................ 82

5.1.3. Budget ................................................................................................................................ 84

5.2. Qualifications ............................................................................................................................. 86

5.2.1. Corey Kimble ...................................................................................................................... 86

5.2.2. Colleen Morgan .................................................................................................................. 86

5.2.3. Erin Radtke ......................................................................................................................... 86

5.2.4. David Smith ........................................................................................................................ 87

5.2.5. Zachary Taylor .................................................................................................................... 87

6. References ......................................................................................................................................... 88

Appendix A: Individual Reports ................................................................................................................. 90

Corey Kimble .......................................................................................................................................... 90

Colleen Morgan .................................................................................................................................... 102



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Erin Radtke ........................................................................................................................................... 118

David Smith .......................................................................................................................................... 137

Zachary Taylor ...................................................................................................................................... 152



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1. Extended Problem Statement

1.1. Need

Mowing the lawn with a standard motor powered lawn mower is an inconvenience,

and no one takes pleasure in it. Cutting grass cannot be easily accomplished by elderly,

younger, or disabled people. Motor powered push lawn mowers and riding lawn mowers

create noise pollution due to the loud engine, and local air pollution due to the combustion

in the engine. Also, a motor powered engine requires periodic maintenance such as

changing the engine oil. Even though electric lawn mowers are environmentally friendly,

they too can be an inconvenience. Along with motor powered lawn mowers, electric lawn

mowers are also hazardous and cannot be easily used by all. Also, if the electric lawn

mower is corded, mowing could prove to be problematic and dangerous. The self-

propelling electric remote control lawn mower is a lawn mower that has remote control

capability. This prototype is robotic user friendly, cost efficient, safe to use, efficient to

use, and environmentally friendly. It can save significantly on labor costs. Along with the

various ages of users, this lawn mower can also be used by people who have disabilities

and are unable to use a regular push, or riding lawn mower. The prototype will also be

automatic and will run on a charged battery with no cords to interfere with operation. This

cordless electric lawn mower includes remote control capability which is less expensive

than a robotic lawn mower with sensor capability. This robot lawn mower design is safe to

use. With its remote control capability the lawn mower stays within the boundaries of the

lawn because the user is able to have fun control over the lawn mower with the controller.

This prototype is also environmentally friendly. There is no need for gas, oil, and engine to

use this device because it is electric powered.



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Figure 12: Needs of Overall Project

1.2. Objective

The objective of the self-propelling electric remote control lawn mower is to extend the

design of currently used lawn mowers, and to improve the capabilities of standard robotic lawn

mowers as well as assuring cost efficiency. This self-propelling lawn mower design is comprised

of remote control capability that is user friendly so most consumers will be able to use this

device. It is safe to use, as well as efficient because it electric powered and cordless. With

these objectives mentioned, the self-propelling electric robotic lawn mower is environmentally

friendly.

The first expected outcome for this project is the creation of a lawn mower that will cut via

remote control, and then adapt that design to create a mower to operate autonomously. There



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are already robotic lawn mowers in production, however, they are not readily abundant and

are expensive. The primary goal is to create a reliable and efficient robotic lawn mower that is

not expensive to build and performs well. The purpose of this project is to alter the already

built lawn mower in such a way that minimal effort will be required to perform the task of

mowing grass. This incorporates designing all of the features necessary to perform all the tasks

posed for this lawn mower to accomplish. Once a final design has been created to the

standards agreed on by the group, parts for the mower will then have to be obtained. The final

design will incorporate communication between both hardware and software components.

The two main aspects of the project needed to be accomplished is the overall safety of the

machine itself and the effectiveness to efficiently cut grass.

The next objective is to automate the mower so that the user is taken out of the picture,

and the user’s only task is setting up the device initially. The primary objective is to obtain a

finished product that will help further advance the mowing industry. The final design of this

mower will have to be cost efficient and within budget in order to make an impact on the

current robotic models of lawn mowers on the market. There are multiple versions of robotic

lawn mowers currently on the market. With this in mind, a major accomplishment, and goal

would be to create a mower that performs as well or better than current robotic mowers at a

significantly lower price.

1.3. Background

The lawn mower was invented in 1830 by an engineer named Edwin Beard Budding.

Budding obtained the idea of the lawn mower after seeing a machine in a local cloth mill which

used a cutting cylinder mounted on a bench to trim cloth to make a smooth finish after

weaving. Budding realized that a similar concept would enable the cutting of grass if the

mechanism could be mounted in a wheeled frame to make the blades rotate close to the

lawn's surface. This realization allowed Budding to produce lawn mowers made of cast iron.



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These lawn mowers featured a large rear roller with a cutting cylinder in the front. Cast iron

gear wheels transmitted power from the rear roller to the cutting cylinder [1].

Nowadays, lawn mowers are useful pieces of machinery that employ a revolving bladeto cut a lawn at a smooth, even length. Since 1830, there have been various lawn mower

designs that have been created. These designs include push lawn mowers, which are suitable

for smaller lawns, and the ride-on mowers, which are capable to cut grass in larger lawns [1].

Other more recent models of the lawn mower contain corded and cordless electric

power. Cordless electric powered lawn mowers are powered by 12 volt rechargeable batteries.

Cordless mowers have the maneuverability of a gasoline powered mower and the

environmental friendliness of a corded electric lawn mower [3].

The latest design of the lawn mower is the programmable robotic lawn mower. A

programmable robotic lawn mower is a lawn mower that is designed to mow a lawn

automatically, without any need for human involvement or interaction. The programmable

robot lawn mower can be programmed with a variety of information which is utilized to mow

the lawn regularly due to the user’s timely schedule. The lawn mower can also be programmed

to mow grass at the desired height. The mechanism of a robotic lawn mower contains wheelswhich allow the lawn mower to navigate the lawn, along with sensors which are used to detect

changes in terrain, fences, and other foreign objects which should not be mowed. Some of

these robotic lawn mowers are equipped with sensors which can interface with other sensors

installed around specific areas to control the robotic mower to stay within its boundaries of the

lawn. Typically, the robot includes a charging station which can be installed anywhere where

there is an electric outlet. Some robotic lawnmowers are solar powered, charging up as they

mow the grass. Most of these robots are equipped with containers for clipping collection sothat the lawn does not need to be raked after mowing [4].



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1.4. Stakeholder goals

The following is a list of goals the will coincide with the self-propelling electric remote

control lawn mower throughout its development:

-To provide remote control capability to a customer for complete control over their lawn

- To develop a system that can be easily used, and is safe for consumers

- To develop a system that will be cost-efficient.

- To always maintain the highest level of safety, and efficiency as possible

- To produce a product that can be marketed towards a demographic interested in using a

self-propelling electric remote control lawn mower and maintaining a groomed lawn



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1.5. Objective Tree

Figure 13: Objective Tree

1.6. Ranking of Needs

The first level of the objective tree shows four needs that the self-propelling electric

remote control lawn mower should comply with. Of these four needs, safety is the first

priority of the self-propelling electric remote control lawn mower It is important that

customers can use this product safely which will give them the ability to use this product

without a high caution level. Second, it is important for the customer to find the system

efficient. If the customer cannot accessibly mow his/her lawn, and there is no comparison

with other lawn mowers, then the design is not efficient to the customer. Third, and is having



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a user friendly prototype. Having a user friendly design will allow for a wider range in

consumers, and users. Lastly, the product must be environmentally friendly. This will allow

the system to not produce greenhouse gas emissions along with noise pollution.



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2. Requirements Specification

2.1. Function Descriptions

A description for each available function can be found in this section of the

document. The function list below includes added components, remote control, and

mower functions.

2.1.1. Added Component Functions

2.1.1.1. Rechargeable Batteries for Added Components

The rechargeable batteries act as the power source for all the added components

that were not originally part of the mower.

2.1.1.2. Deadman’s Killswitch

This function allows the robotic mower to be on only when a button or trigger is

pressed down. This is a safety feature that allows the user to shut the robotic mower

down at any moment.

2.1.1.3. Turn Over Killswitch

This function is to ensure that if the robotic mower were to flip over, it would

shut off. This is a safety feature that ensures there is no injury or damage from a

revealed spinning blade.

2.1.1.4. Sensor



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The sensor function will allow the robotic mower to sense objects in its path. This

can be used as a safety feature as the robotic mower could detect living creature and

stop before causing injury. This can also prevent the robotic mower from damaging itself

by running into a large object in its path.

2.1.1.5. Zero Turn Function

The zero turn function allows for easier control of the robotic mower. The user

will not have to reverse the direction and turn the robotic to make tight turns but

instead has independent controls for turning the direction of the robotic mower.

2.1.1.6. Grass Clipping Catcher

This feature allows for the mowed grass to be picked up and stored in an

attachable bag.

2.1.2. 2. Remote Control Functions

2.1.2.1. Remote Control/Transmitter

This function allows for the robotic lawn mower to be driven by a user using a

remote control. The signals are transmitted from the control to the mower’s receivers.

2.1.2.2. Remote Engagement

This allows the user to engage the robotic mower using the remote control. The

user can turn on/off the mower and engage the self propulsion of the mower to allow the

robotic mower to move.

2.1.2.3. Receiver

The various receivers added to the mower allow for interaction between the



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remote control and the components of the robotic mower.

2.1.3. Mower Functions

2.1.3.1. Mowing Ability

The most important function of the mower is the ability to effectively mow the

grass.

2.1.3.2. Self-Propulsion

This is a function of the mower that allows the mower to move without being

physically pushed by a user.

2.1.3.3. Electric Mower

The electric motor powers the original mower functions. This requires that the

mower be charged, however, the electric motor is environmentally friendly. The

adjustable height function allows the user to adjust the height at which the blade cutsthe grass.

2.1.4. Automation Functions

2.1.4.1. Self-Controlled

This is a function of the mower that allows the mower to mow without being

directly controlled by a user. After being turned on, the mower will begin to mow the

yard without any further user direction.

2.1.4.2. Battery Detection



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The mower will be able to detect when the battery is low and return to the

charging station.

2.1.4.3. Boundary Detection

The mower needs to be able to detect the boundary of the yard so it will not

leave the designated area. This will prevent safety issues as well as insure mowing

efficiency.

2.2. Requirements

2.2.1. Marketing Requirements

Number: MARKETING REQUIREMENTS:

1. Safety

2. User Friendly

3. Keep costs low

4. It should be quiet

5. Environmentally friendly

6. The mower must be durable



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2.2.2. Engineering Requirements

Number: ENGINEERING REQUIREMENTS:

1. Mower must respond to wireless signals from remote

2. Batteries must be easy to charge

3. Height must be adjustable

4. There must be safety killswitches

5. There must be a sensor to detect objects in the path of

mower 6. Able to mow the grass effectively



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2.2.3. Market / Engineering Requirement Trade-off

Safety

User

Friendly

Cost

Efficiency Quiet

Eco-

Friendly D

Mower must respond to↑ ↑

wireless signals from remote

↑ ↑ Batteries must be easy to charge

↑ Height must be adjustable

↑ ↓ There must be safety

killswitches

There must be a sensor to detect↑ ↓

objects in the path of mower

↑ Able to mow the grass

effectively



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2.3. Competitive Benchmarks

2.3.1. Constraints

In the following sections, this document will lay out the major constraints of the

robotic lawn mower.

2.3.1.1. Economic

A function model is needed to correctly exhibit the robotic lawn mower’s

functions. This model, including the mower and components, will have an

implementation cost. The cost of a base electric self propelled push mower will vary

depending on the retailer. Various components will need to be added to the mower

and include servos, a battery, electronics, etc. will have different costs depending on

which vendor is chosen plus the cost of installing the system components. The cost of

the programming software and the remote control must also be considered into the

total cost.

2.3.1.2. Environmental

The robotic mower will be used entirely outside. Therefore, the technology

must be capable to endure a variety of weather elements in order to function

properly. The added components should be minimally obtrusive, and must be

environmentally safe. Substantial interaction with electrical systems within the

mower is necessary due to the nature of the device. The system has no emissions as

the mower is entirely electric. The robotic mower is based off an electric mower

which has a much less negative effect on the environment when compared to that of

a mower with a gasoline engine.



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2.3.1.3. Ethical and Legal

The signals will be transmitted from the remote control at 75 MHz as this is the

reserved frequency band for surface vehicles. This is not a legal issue but done to prevent

radio interference and is a generally accepted rule. Additionally, any failure of the safety

features or control over mower could result in injury or damaged property. The robotic

lawn mower will not breach any existing patents, copyrights, or trademarks.

2.3.1.4. Health and Safety

Safety is a top concern for the robotic lawn mower. Safety features include a

dead man’s kill switch, a flip over kill switch, and a sensor that detects when there is acreature or object in the mower’s path.

2.3.1.5. Manufacturability

The robotic lawn mower should be created such that easy replication of the

mower can lead to its mass manufacturing. The software will be produced within and

installed on a computer that acts as the robotic lawn mower’s server to control many of

the mower’s functions.

2.3.1.6. Political

The system should conform to The American National Standards Institute (ANSI)

issued ANSI B71.1.

2.3.1.7. Social

The user controls should be easy to use. The instructions for use should be



53 | P a g e

readily available.

2.3.1.8. Sustainability

The capability for integration of additional components and effective

communication between software and hardware are essential. Additionally, the added

components should not interfere with the mower’s original mowing functionality. The

robotic lawn mower should achieve high reliability to make certain that it is available for

use at all times.

2.3.2. Standards

In the following sections, this document will list the standards in which the

robotic mower will be created.

2.3.2.1. Safety

The system should comply with The United States Consumer Product Safety

Commission (CPSC) standards.

2.3.2.2. Data Formats

Either Adobe Acrobat (.PDF) or Microsoft Excel (.xls) format will be used

for exported database entry logs.

2.3.2.3. Programming Languages

The databases will be programmed using RoboRealm. The webpage will

be programmed using Adobe Dreamweaver CS5.5. To connect the webpage to



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the database, JavaScript or PHP will be used.

2.3.2.4. Meta-Standards

Communication between the hardware and software will comply with RS-

232 and 802.11.15 standards.



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3. System Design

3.1. Scope

The scope of this project entails separating the project into two main

stages. The first stage of the creation is to take an existing electric lawn mower

and integrate it so the machine is controlled solely by a remote controller. This

purpose of this stage of the project is to construct and trouble shoot all of the

mechanical devices and parts that will be used for this project. There is no

programming in this section of the project, just mechanical hardware and

integration of transmitting, receiving, and relaying components. Once this stage

has successfully been accomplished (no mechanical failures, the user can reliably

cut grass using the remote control and not have to constantly adjust or fix the

machine, and the machine is durable enough to hold itself together after

numerous uses) the second stage of the project can begin to be constructed.

The second stage of this project entails to take the mower created in the

first stage and adapt it so that the machine operates autonomously. The main

control components will be integrated with the existing mower and will be

combined with safety equipment (I.E. tip sensor, camera, range detection, etc…) all

processed by a central computer. The user will be able to program the mower and

then set it in the area needed to be mowed and the mower will begin the task of

mowing until the defined area has been successfully cut. This section is completely

comprised of software and programming since the hardware side was already

taken care of in the first stage. The safety equipment being integrated on the

mower will operate solely off of the state of the mower. Also, the user will still be

able to choose to operate the mower via remote control if they wish to choose to.



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3.2. Context Diagram

Figure 3: Overall design view of project



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3.3. First Stage: Remote Control

3.3.1. Basic Operations

This stage of the project is completely hardware based. An existing lawn

mower will be used rather than try to create one due to time, cost, and

performance. The lawn mower being used is an electric lawn mower. Choosing to

use an electric lawn mower has multiple advantages over using a gas powered

mower. First, the safety factor of using an electric mower over a gas mower is

huge, there is no combustible fuel being used that may be accidentally ignited

seeing that the other components being used are electrical devices. Second, an

electric mower is quieter than and as efficient as a gas powered mower, creating amore peaceful atmosphere while mowing and preserving the environment at the

same time. The only down fall is that a gas powered mower can be refueled

multiple times without much of a time delay where as an electric mower would

either have to be charged or have the battery changed.

The following components will be integrated together to reach the goal of

this first stage:

3.3.1.1. Electric Lawn Mower Base

An already existing mower base will be used for this project. The amount of

time and money that would be required to create our own mower base greatly

outweighed the advantages of purchasing an existing mower and integrating other

parts. An existing mower already has been tested by the manufacturer and lessens

the amount of testing required for the hardware control components in this

section.

3.3.1.2. Remote Control Transmitter and Receiver

The remote control transmitter is the device that the user will operate to

send the appropriate control signal to the mower. The transmitter sends these



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signals to the receiver, which is to be located on the mower base. The receiver is

the part that receives the signal from the remote control transmitter and relays

the input operations to the motor driver.

3.3.1.3. Motor Driver

The motor driver is a part to be located on the mower base that takes input

signals from the receiver and relays the appropriate input signal to the

corresponding component that is requested to be controlled.

3.3.1.4. Rear Motors

There will be two motors that will replace the rear wheels on the existing

lawn mower. These two motors will be independently operated, meaning that a

single motor can be accessed and controlled without the accessing or commanding

the other motor. The reason for this is that the mower will be operated as a zero-

turn device. Zero-turn simply means that the device will be able to rotate around a

central position in one motion. This allows for fewer movements while

maneuvering and less components to worry about for main controls. The two rear

motors will provide the propulsion for the mower (Forward and reverse) and also

the steering for the machine.

3.3.1.5. Caster Wheels

A caster wheel is wheels that can run freely on a central axis. The wheel

can also rotate a full 360 degrees in either direction. The use of this type of wheel

will allow the mower to fully utilize the independent rear motors and their zero-

turn capabilities.

3.3.1.6. Miscellaneous

This stage of the project will require a good amount of wiring and

connections between components. Wire, batteries, and other small parts will be

required to properly connect, fasten, and operate the components in this first

stage.



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3.3.1. Wiring Diagram

The figure seen below, Figure 2, the diagram demonstrates the basic wiring

that is needed to be accomplished for the first stage of this project. The

information sent from the remote control transmitter is received by the receiver.

The receiver then takes theses input signals and sent the appropriate signal to the

proper output component. If the kill switch is used from the remote, the signal is

sent to the receiver and then transferred to the kill switch on the mower, cutting

off all power. If the main maneuvering controls are manipulated on the controller,

the signals are sent to the receiver and the signals are transferred to the motor

driver. The motor driver then takes in the signal and sends the appropriate voltage

values to the desired component.

Figure 4: Main component wiring diagram for first stage.



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3.3.2. Remote Control Interface

There are only three main features that will be used on the remote

controller.

Figure 5: Controller to be used

3.3.2.1. Kill Switch

The main purpose of this switch is to cut off the main power for the mower

itself. This safety measure will allow for safer travel from one place to another when

relocating the mower or if the user wishes to reposition the mower without cutting

the grass. When the mower is off and the switch is engaged, the mower will turn on.

When the mower is on and the switch is engaged, the mower is turned off.

3.3.2.2. Left Motor Control

The function of the left motor control is to simply provide power to the rear left

motor. Since the motors are independently controlled, power can solely be controlled



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away from the rear right motor. This independent control between the two motors

allow for the mower to move in a variety of different movements.

3.3.2.3. Right Motor ControlThe function of the right motor control is to simply provide power to the rear

right motor. Since the motors are independently controlled, power can solely be

controlled away from the rear left motor. This independent control between the two

motors allow for the mower to move in a variety of different movements.

3.3.3. Functions of Overall Operation

The main functions seen in the first stage of this project are the relations

between the user controlling the mower and how the mower moves based on the

user inputs. The precision between what the user tells the mower how to move via

remote control and how the mower responds is very important.

Similar to a normal remote controller, there are two main joysticks that the

user will use to maneuver the machine. If both joy sticks are pushed forward, the

mower will move forward. If both joysticks are pushed back, the mower will move

in reverse. If the left joystick is pushed forward and the right joystick is pushed

back, the mower will spin in a clockwise direction. If the right joystick is pushed

forward and the left joystick is pushed back, the mower will spin in a

counterclockwise direction.

The kill switch will also operate as stated if the user wishes to engage the

switch.

Since this stage of the project is hardware based and the operations of the

machine are user based, the user has all of the control over the machine and will

not operate unless the user interfaces with the mower via remote control.



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3.3.4. Testing

Since this stage of the project is comprised of only hardware components, each

individual component will be separately tested before being integrated into the

system.

The electric mower will be tested by assembling the machine (If necessary) and the

operating it as a normal push mower would be operated. Any defects or issues will the

mower itself will then be addressed and fixed.

The rear motors will then be tested separately for overall effectiveness. The motors

will have to be able to operate in forward and reverse as well as being properly

powered by two twelve volt batteries set in parallel.

Next, the receiver will be tested to make sure that it can receive a signal from the

remote control transmitter. Once a connection has been made, the receiver can then

be wired to the motor driver. Once the receiver has been wired to the motor driver,

the motors and twelve volt batteries can then be connected to the motor driver as

well. Then the remote control transmitter will be used to send movement signals to

the receiver to test and see if the proper output signal is displayed. Once the

transmitter and receiver are properly connected and set given the respective and

correct output of the motors are checked, this whole assembly can be mounted to the

mower.

Once the controlling assembly is mounted to the mower, the rear motors can

replace the rear wheels and the caster wheels can replace the front wheels. After

everything is properly installed onto the mower base, the output from the receiver

given movement inputs from the transmitter will be checked again. If the movement

correlation between the remote control transmitter and the corresponding movement

is as it is defined, the kill switch can then be added to the mower.



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The kill switch is to be placed between the mower battery and the blade mower,

when the switch is one, the mower blade will spin, when the switch is off, the mower

blade will not spin. The switch is then connected to the receiver so that it can operate

accordingly to whatever signal is sent to it from the remote control transmitter. After

it is installed, the kill switch will be tested.

The remote controlled mower will then be tested for the range at which it can

operate, the effectiveness of the controls at the extreme ranges, the effectiveness of

the kill switch at all ranges, and the overall effectiveness of cutting the grass via

remote control. Any mechanical or wiring issues found will be fixed accordingly.

3.4. Second Stage: Automation

3.4.1. Basic Operations

The object of this stage of the project is to take the mower created in the

first stage of this project and automate it. This means that the mower will be able

to complete the task of mowing the lawn by itself (little human interface). This

part of the project is completely software based and will require an extensive

amount of programming to successfully have mower operate independently.

3.4.2. Sensors

Before getting into the main programming of this stage of the project,

there are going to be a few additional components integrated into the mower to

help aid the overall goal of this stage.

3.4.2.1. Tilt Sensor

A tilt sensor will be added to prevent the mower blade from running if the

mower somehow overturns. The tilt sensor will measure the angle at which the

mower is operating at and if the mower exceeds a defined angle, the mower blade

will shut off until the angle of the mower returns to a safe state. Also, if the mower

becomes completely overturned (>175 degrees) then the entire system will shut



64 | P a g e

off to preserve the energy and safety of the machine itself and for anyone

attempting to flip the mower back over. The tilt sensor will constantly relay the

mower’s angle back to a central processor where it will be evaluated accordingly

so that the proper procedure can be executed.

3.4.2.2. Object Avoidance

The mower will also be fitted with sensors that will scan the area in front of

the mower to detect any foreign objects that may hinder the mower’s movement,

cause harm to the mower, or cause harm to the foreign object. The sensor will

relay its information to the central processor where the computer will analyze the

data. If the program sees a foreign object, the route at which the mower is

mowing in will be altered to avoid the object.

3.4.2.3. Range Sensor

Since the user will still be able to use the remote control transmitter even in

this stage of the project, a range sensor will be integrated to prevent the mower from

traveling outside of a defined range. This will prevent the circumstance of the mower

being placed outside of the defined area and then reinstated into autonomous mode.

This would create an issue of possibly property destruction, machine destruction, or

harm to another individual. For these reasons, the range sensor will not allow the

mower to travel outside of a defined area in either remote or autonomous modes.

3.4.3. Processor

The purpose of the processor is to read in the values of the sensors integrated

into the mower design and send the processed data to the computer. The processor

will also take data from the computer and send the correct data to the motor driver to

maneuver the mower according to the defined route programmed. The processor is a

very important part to this stage of the project. The processor is what will receive and

relay given data to the respective component on the mower so that the end output

reflects what the mower is programmed to do.



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3.4.4. Computer

The computer is the piece of equipment on which the program for automation

will be stored. The computer will also read in data from the processor that contains

the information received from the sensors on the mower. The computer executes the

program stored on it and updates the program with the information received from the

sensors. The program that is stored on the computer is very important and it is

imperative that the program is very reliable and is not prone to system failures.

3.4.5. Programming

This part of the second stage is going to take the longest amount of time

overall for the project. The program to be created for making the mower operate

autonomously will have to be very extensive and cover every possibility and situation

that the mower may encounter. The software being used to create this program is

called RoboRealm. It is a widely used piece of software that is used primarily to control

robotic features. The way of which the program is written also depends on the form of

boundary guidance being used. There are three main possibilities that are available to

make the mower run autonomously. There is the one method that used an electric dog

fence to mark off the areas in which the mower can move in, a method which uses a

GPS (Global Positioning Satellite) to define the area in which the mower can move, and

there is method called “Trace and Record” where the area wanting to be mowed is

traced with the mower, where the route taken is recorded and stored so the mower

can follow the same path at a later time. The actual method being chosen has not

been decided as of yet, but all three methods are very doable and have their

advantages and disadvantages.

3.4.5.1. RoboRealm

This software will be used to create the program that will enable the mower to

operate autonomously. The software will be used to create the general basis off which

the mower will operate and allow for alterations in the program in for the route of the



66 | P a g e

mower based off of the inputs from the sensors. The overall program also depends on

which of the three methods for the autonomous movement is chosen.

3.4.5.2. Dog Fence BoundaryAn electric dog fence is operated by burying an electric line that defines the

boundary in which a dog (In our case the mower) can move, and an electric collar

receiver. If the mower tries to proceed outside of the defined boundary, a signal is

sent to the electric collar that would produce a shock if a dog was wearing the collar.

In the case of using the mower with this idea, if the mower receives this signal, it will

realize that it has reached a boundary and that it can proceed no further in that

direction. The mower will then have to change its direction and proceed until it

reaches the boundary again. This procedure is repeated until the mower has covered

the entire defined area.

This form of boundary has already been used by pre-existing autonomous lawn

mowers. The idea is based off of the robotic vacuum cleaner “Roomba” and the

mowers with this design mow the yard in a randomized pattern. Though this method is

an effective and simple way to autonomously cut grass, the finished product does not

look as satisfying as it would if a human actually mowed the same area.

3.4.5.3. GPS Boundary

This form of boundary detection requires the use of a GPS unit. The idea is that

the user would be able to define an area in which the mower is to operate, setup a

waypoint pattern on the GPS for the mower to follow. This form of boundary and

route control would require interfacing between the GPS unit and the computer,

programming to have the mower move from waypoint to waypoint, and the ability for

the GPS to have a clear communication with the satellites.

This process of automation will definitely work, under the right circumstances.

The precision of GPS is only around 3-6m on the ground; this is also an issue for this



67 | P a g e

project seeing that this is a very large range of error for the precision needed to cut a

lawn. The GPS also has to have constant communication with the satellites in order to

operate fully; any disconnections will hinder the mowing process and cause major

delays. This form is completely doable, but the amount of programming, interfacing,

testing, and efficiency involved with this form is something that is not needed for this

mower project.

3.4.5.4. Trace and Record Boundary

This last boundary system is a memory based approach to solving this issue

with automation. The idea is that the software written will allow the user to pass the

mower over the lawn in the order and fashion they wish the lawn to be cut. During this

process, the computer will store the movement of the mower in its memory for later

use. Once the user is finished with the yard, the program will stop recording and the

pattern will be saved. The next time and any time after the user wishes to mow the

lawn, the mower can be placed in the starting position and the program that originally

stored the program can be run to have the mower begin mowing. The program will

send the directions in which the mower originally moved to the motors in the same

order that the movements originally happened. This will in turn recreate the sameexact route that was previously recorded. Once the pattern has been completed, the

lawn should then look approximately the way the pattern was stored.

This form of automation seems to be the leading candidate for the program to

be used for our design. This form will require a good amount more programming

compared to the dog fence idea, but the overall look and control over the pattern of

cut grass will outweigh this burden. The dog fence is easy to set up and program, has

been accomplished before, and there are many tutorials on how to accomplish this

form of boundary system. In order to add something new to this field of automation, a

process in which the pattern of the grass can be defined and then repeated over and

over again would be a giant leap for this industry. The addition of the sensors



68 | P a g e

combined with this boundary system will be able to provide a finished product that the

user still has control over.

3.4.6. TestingThere is going to be a great amount of testing for this stage of the project.

Because the mower will be able to operate without the help of a user, the program

being created will have to be very reliable and be able to successfully cut a lawn

without causing harm to the environment not wanting to be cut, the mower itself, or

any persons around the mower.

The program will have to be tested extensively in order to define the extents of

which the program will be able to control the mower. This means that the largest size

of yard that can be cut by the mower controlled by the program will have to be

discovered and made aware to the user before the use. The program would also have

to be tested for the precision of cutting. If there are areas that the mower misses, the

program may have to be altered in order for these areas to be reached. The program

will also have to be tested for its ability to fully control and receive information for the

components and sensors integrated onto the lawn mower.

The integration between the sensors integrated onto the mower between the

processor and the computer will also have to be tested to ensure that the computer is

constantly receiving their corresponding data. The longevity of the battery providing

power to the computer and the processor will have to be tested so that the computer

does not shut off in the middle of cutting a lawn. The conditions of which the mower

will be operating in will also have to be tested in order to provide data that the mower

can operate in different conditions. Finally, the program will have to be tested for

duration of time running at all of the possibly extreme cases in order to test for

failures. In order to have a reliable system, failures or errors cannot happen while the

mower is operation. The program will have to be able to constantly update itself, be



69 | P a g e

able to record, replay, and rewrite from memory, and be related the executed

program into physical movements.

4. SOFTWARE TESTS

4.1. Remote Control – Transmitter Signal

Action

Outcome

Inputs Expected

Effects

Success Remote control

signal to mower

transmitter

satisfactory

The blade

on the mower

will be free to run

and cut grass.

Failure Remote control

signal to mower

transmitter is not

satisfactory

The

mower will not

power on.

Possible message

or light on

remote control

depicting signal

error.

4.2. Mower Orientation

ActionOutcome

Inputs ExpectedEffects

Success Mower on all four

wheels

The blade

on the mower



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will be free to run

and cut grass.

Failure Mower is not on

all four wheels

(lopsided or

upside down)

The

mower will not

power on.

Possible message

or light on

remote control

depicting mower

orientation error.

4.3. Battery Power

Action

Outcome

Inputs Expected

Effects

Success Battery power

sufficient

The blade

on the mower

will be free to run

and cut grass.

Failure Battery power

insufficient

The

mower will not

power on.



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Possible message

or light on

remote control

depicting battery

power error.

4.4. Obstacle Sensor

Action

Outcome

Inputs Expected

Effects

Success Obstacle sensors

clear

Mower

with active blade

free to cut in

direction of

desired motion

input by user

onto the remote

control toggle.

Failure Obstacle sensors

signal nearby

object

Mower

deactivates

blade, system

carries out

emergency

shutoff. Possible



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messages or

lights on remote

control depicting

unsafe

environment

alert.

4.5. Active Blade

Action

Outcome

Inputs Expected

Effects

Success Remote control

signal to mower

transmitter

satisfactory

Mower on all four

wheels

Battery power

sufficient

The blade

on the mower

will be free to run

and cut grass.


signal to mower

transmitter is not

satisfactory

Mower on all four

wheels

Battery power

The

mower will not

power on.

Possible message

or light on

remote control

depicting signal



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sufficient error.


signal to mower

transmitter is

satisfactory

Mower is not on all

four wheels

(lopsided or upside

down)

Battery Power

sufficient

The

mower will not

power on.

Possible message

or light on

remote control

depicting mower

orientation error.


signal to mower

transmitter

satisfactory

Mower on all four

wheels

Battery power

insufficient

The

mower will not

power on.

Possible message

or light on

remote control

depicting battery

power error.


signal to mowertransmitter is not

satisfactory

Mower is not on all

The

mower will notpower on.

Possible

messages or



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four wheels

(lopsided or upside

down)

Battery Power

sufficient

lights on remote

control depicting

signal error.


signal to mower

transmitter is

satisfactory

Mower is not on all

four wheels

(lopsided or upside

down)

Battery Power

insufficient

The

mower will not

power on.

Possible

messages or

lights on remote

control depicting

mower

orientation and

battery power

errors.


signal to mower

transmitter is not

satisfactory

Mower on all four

wheels

Battery powerinsufficient

The

mower will not

power on.

Possible

messages or

lights on remote

control depicting

signal error.

Failure Remote control The



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signal to mower

transmitter is not

satisfactory

Mower is not on all

four wheels

(lopsided or upside

down)

Battery Power

insufficient

mower will not

power on.

Possible

messages or

lights on remote

control depicting

signal error.

4.6. Mobility

Action Outcome Inputs Expected

Effects

Success The untouched

remote control

toggle is moved

in direction of

desired motion

Remote control

signal to mower

transmitter

satisfactory

Mower on all

four wheels

Battery power

sufficient

Mower

with active blade

cuts in direction

of desired motion

input by user

onto the remote

control toggle.



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Obstacle sensors

clear

Success Active remote

control toggle

moved in

direction of

desired motion

returns to center

Mower

with active blade

ceases motion.

Cuts in place.


toggle moved in

direction of

desired motion

Remote control

signal to mower

transmitter not

satisfactory

Mower

deactivates

blade, system

carries out

emergency

shutoff. No

motion executed.

Possible

messages or

lights on remote

control depicting

signal error.

Failure The untouched

remote control

toggle is moved

in direction of

Mower

deactivates

blade, system

carries out



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desired motion

Mower is not on

all four wheels

(lopsided or

upside down)

emergency

shutoff. No

motion executed.

Possible

messages or

lights on remote

control depicting

mower

orientation error.


remote control

toggle is moved

in direction of

desired motion

Battery power

insufficient

Mower

deactivates

blade, system

carries out

emergency

shutoff. No

motion executed.

Possible

messages or

lights on remote

control depicting

battery power

error.


remote control

toggle is moved

Mower

deactivates

blade, system



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in direction of

desired motion

Obstacle sensors

signal nearby

object

carries out

emergency

shutoff. No

motion executed.

Possible

messages or

lights on remote

control depicting

unsafe

environment

alert.

4.7. Direction of Motion

Action

Outcome

Inputs Expected

Effects

Success Toggle directed

due North

Servos

point straight.

Axle powered to

motion mower

forward.


Northeast

Servos

point in angle of

toggle to the top

right. Axle

powered to

motion mower

forward.



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Northwest

Servos

point in angle of

toggle to the top

left. Axle

powered to

motion mower

directly forward.


due East

Servos

point to the right.

Axle powered to

motion mower

forward.


due West

Servos

point to the left.

Axle powered to

motion mower

forward.


Southeast

Servos

point in angle of

toggle to the

bottom right.

Axle powered to

motion mower

backward.


Southwest

Servos

point in angle of

toggle to the



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bottom left. Axle

powered to

motion mower

backward.


due South

Servos

point straight.

Axle powered to

motion mower

backward.



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5. Project Plan

5.1. Project Management

5.1.1. Preliminary Work Breakdown

PRODUCT DEVELOPMENT:

Task: Description Resources

Learn RoboRealm Explore and develop the knowledge to efficiently

and appropriately use RoboRealm

Google, RoboRealm

Order Parts Order the mower, remote control, reciever, etc. Websites (Tower

Hobbies, etc.)

Produce Functioning

Remote Control

Mower

Add the necessary parts to the mower for

communication between mower and remote

control

Motor Driver, 2 Wheel

Chair Motors, Caster

Wheels, 2 12 V Battery

Write Functions Write the functions and programs necessary to

form communication between the software and

hardware

Computer, RoboRealm

Prepare Mower for

Automation

Add other parts to mower to prepare it for the

integration stage

Sensors, Computer,

Processor, (3nd) 12 V

Battery

Integrate Hardware &

Software

Provide input to processor for output procedures All previous resources



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5.1.2. Project Timelines

Timeline: First Stage: Remote Control Lawn Mower

Task: June July August

Explore, Learn, and Understand RoboRealm

Order & Obtain all Parts for the First Stage

Prepare Complete Any Mechanical Work on

Mower Itself, i.e. Remove Handlebar

Add all Necessary Parts to Mower for First Stage

Form Communication between Remote Control &

Mower

Troubleshooting & Debugging

Order & Obtain some Parts for Automation Stage

Gantt Chart: Second Stage: Automation

Task:

Week

#1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14 #1

Write Functions

Prepare Mower

for Automation

Integrate H.W.

& S.W.

Product Testing

Troubleshooting

& Debugging



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User Guide

Final

Documentation

Design Fair



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5.1.3. Budget

Budget for the Remote Control Lawn Mower

Parts: Amount

Needed:

Cost/Each: Total:

Self Propelled Lawn Mower 1 $200.00 $200.00

Remote Control w/ Receiver 1 $99.99 $99.99

Grass Catcher 0* $100.00 $0.00

Motor Driver 1 $124.99 $124.99

Electric Wheel Chair Motor 2 $50.00 $100.00

RoboRealm Software 1 $0*** $0.00

12 V Battery 2 $18.00 $36.00

Caster Wheels 2 $29.64 $59.28

Wiring, Miscellaneous

Electrical Accessories

N/A N/A $50.00

Grand

Total:

$670.26**

*The intended plan is to purchase a Self Propelled Electric Mower with the grass catcher bag

already attached from Amazon.com

**These prices are estimates for the different components based off of Amazon.com,

Towerhobby.com, Engineeringdimensions.com, and Ebay.com.

***Dr. Klinkhachorn will be contributing the RoboRealm license for the group to use.



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Products to Purchase for Second Stage: Automation*

3rd

Battery

Processor

Sensors

Boundary – Either GPS or Dog Fence Equipment

*Some of these parts may be recycled from previous Senior Design classes.



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5.2. Qualifications

5.2.1. Corey Kimble

Corey Kimble is seeking his Bacherlor’s Degree in Electrical Engineering at West Virginia

University. Corey is currently furthering his studies emphasizing his degree in Communications.

Corey, on the dean’s list for his entire college career, participated in the Computer Club and the

Engineering Club at Potomac State College of WVU. Because of this, Corey will be able to contribute

his research to the LawnBot group. In addition, he is a member of the Sigma Phi Omega Honor society

and has developed a wealth of management skills. Corey is currently experienced in of Java, C++,

Microsoft Vizio, Altera Quartus II, PSCAD, and MATLAB. Corey will be spending his summer learning

the knowledge of RoboRealm.

5.2.2. Colleen Morgan

Colleen Morgan is studying Electrical Engineering with a concentration in Communications at

West Virginia University. She is a member of the Alpha Omega Epsilon Colony at WVU, aninternational engineering sorority. She currently serves as the Vice President of A.Ω.E., but has also

had the role of the Treasurer. Both of these executive board positions have strengthened her

leadership skills. In addition, Colleen works for the Associate Dean of Engineering at West Virginia

University. She has familiarized herself with Java and Assembly, and is greatly experienced in

MATLAB, PSPICE, and Altium. She too will be learning the language of RoboRealm for the purpose of

the mower.

5.2.3. Erin Radtke

Erin Radtke is perusing a degree in Electrical Engineering at West Virginia University. Erin has

spent her summer’s working at NAVAIR and currently holds a Co-op position with the company. At

NAVAIR, Erin has furthered her knowledge by assisting with systems testing and various documenting.



87 | P a g e

Erin is currently emphasizing in both Controls and Communications at WVU. She has spent her time

at school learning JAVA, MATLAB, and PSPICE. Erin has plans to further her computer experience with

RoboRealm.

5.2.4. David Smith

David Smith is obtaining his Electrical Engineering degree at West Virginia University. He plays

the current role of an IT Student Technician at WVU where he is able to experience hands-on

involvement with hardware and software, which will greatly help the LawnBot group. In addition, he

was an intern at International Coal group where he recreated different P-SPICE schematics. David has

a great deal of experience with the following programs: Matlab, Simulink, Java, P-SPICE, AutoCAD, and

SurvCADD. David is excited to learn RoboRelam this summer for the purpose of the lawn mower.

5.2.5. Zachary Taylor

Zachary Taylor is also studying Electrical Engineering at West Virginia University. Fortunately,

for the LawnBot Senior Design Group, Zachary has developed a great deal of knowledge from his

experience interning in the past and currently. He was an intern at NASA IV&V where he spent his

time looking over safety documents. He now is currently employed by the R&E Electric Company and

has learned many different manufacturing and troubleshooting skills to contribute to the design of the

Remote Control Lawnmower. Furthermore, he has an abundance of computer experience in the

following programs: Borland Together, DOORS, AutoCAD (2006-2010), Pro Engineer, Adobe

Photoshop, Adobe Dreamweaver, JAVA, and MATLAB. He too will become experienced in RoboRealm.



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6. References

[1] "Mower History." The Old Lawnmower ClubCollection, Preservation and Display of Old Lawn

Mowers. N.p., n.d. Web. 29 Feb 2012.

("Old Lawnmower ClubCollection, Preservation and Display of Old Lawn Mowers")

[2] "Riding or Push Lawn Mower – Which One Should You Get?." Lawn Mower and

Trimmer Reviews. N.p., 07 11 2011. Web. 29 Feb 2012. <http://www.lawnmower-

reviews.com/riding-or-push-lawn-mower-which-one-should-you-get>.

("Lawn Mower and Trimmer Reviews")

[3] Diggs, Steven. "Corded Vs. Cordless Electric Lawn Mowers." ehow . N.p., n.d. Web. 29 Feb

2012. <http://www.ehow.com/about_6581493_corded-cordless-electric-

lawnmowers.html>.

(Diggs)

[4] "Lawn mower robots are Coming Out of the Garages of Hobbiests and Into

Businesses.." Robots and Androids. N.p., n.d. Web. 29 Feb 2012.

http://www.lawnmower-/

http://www.ehow.com/about_6581493_corded-cordless-electric-lawn-




http://www.lawnmower-/



89 | P a g e

<http://www.robots- and-androids.com/lawn-mower-robots.html>.

("Robots ")

[5] "Robotic Lawn Mowers." Super Lawn Mower . N.p., n.d. Web. 29 Feb 2012.

<http://superlawnmower.com/category/robotic-lawn-

mowers/>. ("Super Lawn Mower")

http://www.robots-/

http://superlawnmower.com/category/robotic-lawn-mowers/




http://www.robots-/



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Appendix A: Individual Reports

Corey Kimble

Robotic Lawn MowerEE 480 Senior Design

Corey Kimble

4/11/2012



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Executive Summary:

The group has been tasked with creating an automated lawn mower in order to combat

the need to physically mow a lawn. To accomplish this task the group first plans to create a

mower that can be remote controlled from one location. This will allow the user to sit and control

the mower as it cuts the grass.

The project has a variety of needs and objectives. The needs consist of safety, reliability,

cost efficiency, user friendliness, effectiveness, and durability. The objectives consist of

designing a final schematic for the mower, obtain the necessary hardware and software

equipment needed for the mower, developing communication between the hardware, software,

and the remote control, developing a safety kill switch(s) for the mower, have the mower cut the

lawn efficiently, and finally add additional design ideas to improve consumer allure and improve

safety features.

It is important to understand the background of the project and what has already been

done to make a robotic lawn mower a practical consumer commodity. Robotic lawn mowers are

already on the market, but they are expensive and inefficient. However, using what has already

been done and building upon it can result in a safe cost efficient robotic lawn mower.

The basics of the ideas behind the current lawn mowers can be used to develop an

efficient robotic lawn mower. The ideas this project focus on are the spinning blade, self- propulsion, and an electric motor. Ideas that are used in other areas of the market such as remote

controlled toys and GPS systems are also useful for the project.

The final goal is to produce a prototype for a mower that a consumer can enjoy to use. It

will be a fully functional remote controlled lawn mower. The final design for the robotic lawn

mower will be a machine that is effective at mowing, safe to use, and relatively inexpensive.



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Problem Statement:

The problem that this project addresses is the physical labor involved with mowing a

lawn. For most the physical toll taken while mowing is taxing to the body. Physically

handicapped people and the elderly especially have a concern when mowing their lawn and often

must have someone to do it for them. This problem is addressed with the idea for a remote-

controlled electric lawn mower. Anyone could mow the yard with this innovative mower.

The first step in creating this mower is to design an idea to modify a mower to be remote

controlled. This project is not about reinventing the mower, but making it a better product. The

group will start with an electric self-propelled lawn mower. The ability to self-propel, have a

working blade, and running off electricity will be fully utilized. The controller would add the

ability for a user to control speed and direction of the mower from a distance using a remote

control.

Robotic lawn mowers are a relatively new idea as the lawn mowers were first created in

the early 19th century around 1830. However, since 2005 their popularity has increased

profusely. Most of these mowers require the user to lay a boundary wire into the ground similar

to an invisible dog fence. The robotic mower then would be able to sense the boundary and

therefore, only mow within the specified areas.

These mowers are technologically advanced and contain design ideas that are quitesophisticated. Some of these features include sensors that can detect living creatures or even rain

fall and the ability to be solar powered. These mowers are praised for being the safest mowers

available. Because the users are not required to be anywhere near the mower as they operate it,

they are much less likely to suffer an injury related to mowing. The biggest appeal these mowers

offer is that the user has to put in virtually no physical work to have their yard mowed after

initially setting up their system.

Most of these robotic lawn mowers are not practical for the general public as their price

ranges can be very high, most over $1000. Another problem with these mowers is their

efficiencies. In order to use most of the robotic mowers, the user must first set up the boundary,

which requires the work of digging into the ground to bury the boundary wire and can take a

long time especially for larger yards. Although this is a one time inconvenience, many believe



93 | P a g e

this problem should be eliminated based on the buying price for these devices. Some robotic

mowers with the sensors detecting living creatures may stop when an animal is in its path. The

user would then have to reactivate the mower before it could continue to mow, which is an

inconvenience. These mowers have been reported to take twice as long to mow the lawn as a

consumer using a normal conventional mower would. Another concern is the durability of the

mower. With a high buying price, many would believe these mowers wouldn’t need as much

maintenance as they require.

The actual quality of the performance the robotic lawn mower does is a topic that must be

considered. Many of the robotic lawn mowers on the market today have trouble mowing yards

that are not entirely flat. Angles of slope in the yard greater than 15 degrees prove to be difficult

for the mower. A yard with many obstacles and hills is nearly impossible for the robotic mowerto mow. Some users of these robotic mowers also note that the mower does not do as good a job

as a person would as far as how neat the yard looks.

http://en.wikipedia.org/wiki/File:Automower_Solar_Hybrid.jpg



http://upload.wikimedia.org/wikipedia/commons/9/9d/Automower_Solar_Hybrid.jpg




94 | P a g e

Significant Technologies:

There are many existing technologies that can be used to develop an efficient robotic

lawn mower. As the project is not about recreating the lawn mower, the basic functions of a lawn

mower can be used for the robotic lawn mower.

The lawn mower was first invented around 1830 by Edwin Beard Budding. Budding was

an engineer from England, who came up with the idea after seeing a machine that cut cloth. The

first motor mowers appeared in the 1890s. By 1950, the technology had increased and mowers

were becoming relatively inexpensive. Over the last thirty years lawn mowers become

remarkably similar to current lawn mowers.

A lawn mower has a simple design to operate the blade. The shaft is connected to a

rotating sharp blade that cuts the grass as it moves at a high angular frequency. The grass is

usually sprung out of an opening on the side of the metal frame that houses the blade or it can be

sucked into a bag.

Self-propelled lawn mowers are of interest as they are a building block to the robotic

lawn mower. Self-propelled lawn mowers are attached to a drive-train. This means that when the

engine spins, it turns a gearbox which then turns the mower’s wheels. This is beneficial as the

burden of pushing these mowers is significantly lowered. Most mowers are heavy and manually

pushing them requires plenty energy. This project is focused on self-propelled mowers with anelectric engine.

Remote controlled cars are useful for the project as well. Remote control cars allow a

user to operate the vehicle from a remote control. Taking these components and adding them to

the lawnbot allows the user to then operate the mower with a controller. Other useful

technologies are dead man’s switches. These allow the mower to shut off in certain

circumstances. For example, if the mower were to flip over a dead man’s switch could shut off

the blade for safety concerns. These technologies can be implemented using computer chips

connected to the lawnbot.

The components that require use of computer chips can be implemented using

programming technologies. The group will use RoboRealms to program these components. This



95 | P a g e

technology has been developed to make programming of computer components in robotics

easier.

Robotic lawn mowers have recently been introduced to the market. Some of these

mowers have technology such as solar power, as can been seen in the figure. The group can

research these already created mowers to learn how to make them more efficient and cost

effective.

Objective and Needs (Expected Outcomes):

The project has many needs associated with it. However, the most important need for this mower

is safety. For ethical reasons, the mower causing injury would be horrible. As for business

reasons, injuries could lead to lawsuits which should be avoided at all costs. Safety can be

accomplished with design ideas such as kill-switches and possibly sensors or a boundary wire.

Reliability would be the next most important need. The lawn mower should be able to

operate with little maintenance. The consumer would want to be able to count on the mower

when considered necessary.

Cost efficiency would be the next need to address. The group is working within a limited

budget. If the product were to be produced for the consumer use, the need for it to be inexpensive

is important to make it a practical product.User friendliness is also an important need. The mower should be designed so that any

user could operate the machine easily with the remote control and without having an extensive

knowledge of the product. A consumer would want to be able to operate the mower with as little

ease as possible.

Effectiveness of the mower is a need that must be attended. Consumers want a mower

that cannot only be remote controlled but can actually do a good job mowing the lawn as well.

Consumers also consider how neat their yard looks after the mow.

Durability would be one the last needs to be considered. It is still an important need

however as users would want a mower they can trust to operate when it’s needed. Also, the

mower should still work as effectively years from now as it will initially.



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Objectives cover the project from start to finish. The first objective in order of

importance would be to form a final design for the project. The final design will include what

hardware and software are needed and how they will be used to create the mower.

Obtaining the software and hardware necessary for the project would be the next step.

This will be done by selecting the items needed from our final design. The group will then order

the parts through WVU.

The third objective would be to have proper communication between the software,

hardware, and the remote control. This is important as the user should be able to control

everything from the remote. The robotic lawn mower should respond correctly to given

commands.

The fourth objective would be to implement kill switches in both the hardware andsoftware. This would possibly include an automatic kill switch that would shut down the mower

and/or blade if it were to flip over. Another possible kill-switch would be one the user could

engage such as a dead man’s switch (such as a trigger) or a push button.

The final objective would be to make sure the mower actually is able to efficiently cut a

yard by using a remote control. This would mean that all the other objectives were implemented

and the mower could mow comparable to a regular lawn mower. This would be considered a

success if a user could use the remote controller to move the mower and effectively cut the grass.

Additional objectives would be decreasing power consumption, making the mower fully

automated, make the mower silent or very quiet. Additional safety measures to consider would

be the sensors to detect living creatures or objects in the way. A boundary wire similar to a dog

fence that would activate a kill-switch when crossed is another safety feature to consider.

In addition to the general idea for the mower, other design issues will need to be

considered such as safety features and consumer incentives. These ideas will be discussed later

and consist of ideas from kill-switches to adding a bag for clippings.

There is a wide Varity of design ideas associated with the mower that range from adding

consumer interest to minimizing safety concerns. These are ideas that are in addition to the basic

designs necessary to build the mower. They are not designs that are required to be added for the

mower to operate correctly, however, they would instead add to the total value of the mower.



97 | P a g e

A concern would be if the mower would happen to flip over. In this case, a kill-switch

would be essential. A kill-switch could turn the mower off to minimize safety issues. This type

of kill-switch would be automatic and not activated by the user.

Another safety concern would be harming people or animals that may be in the path. A

design idea to combat this issue would be having a sensor that could detect something in the path

of the mower. The mower could stop or shut off when an object is detected in its course.

When considering functionality of the mower, the weight must be considered. The mower

would ideally weigh close to that of a current electric lawn mower. A heavy mower would bring

its own lists of concerns such as being too heavy for the electric motor to move it efficiently.

This problem can be managed by designing a well-organized blueprint for the mower.

A design idea to make the mower more user-friendly would be to add the zero-turnability. This would allow the mower to make tight turns when mowing. Instead of backing up

and moving forward again as a traditional mower, this ability would allow the mower continue

without going into reverse.

In order to make the mower more appealing to consumer, an idea to add a bag for

clippings could be added. This would allow the mower to send the clipping into a bag attached to

the mower opposed to sending the clippings in the yard. This is an incentive to consumers as it

keeps the yard looking neat and eliminates a need to go back after the mowing to collect the

clippings. One problem associated with this idea, however, is that the bag would need to be

emptied when filled.

The controller its self has its own needs separate from that of the body of the mower. A

top concern is that of adding a user activated kill-switch located on the mower’s controller. This

could be a trigger that is held in order for the mower to operate. With this idea, if the mower

needs to be shut off suddenly, the user could just simply release the trigger. This could prevent

safety issues by allowing the user to determine when to shut off the mower. The only problem

with this idea is that there is the inconvenience of the user having to keep one hand on the

controller at all times of use. Another idea for a kill-switch would be a button on the controlled

that would shut down the blade and/or mower when pressed. This would eliminate the need to

hold a trigger the entire time, however could not be accessed as quickly as the dead man’s

switch.



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Another top concern for the controller is the range of distance that the mower could

operate from the controller. This is a potential problem as the user would not want to move along

with the mower but would rather relax as they control the mower from one spot. The toggles on

the controller are another issue, as the controller used won’t be created by the group but instead

bought preassembled. Other concerns with the controller are turning and propulsion using the

remote.

It should be noted that this robotic lawn mower will be created with a green initiative.

The mower will be environmentally friendly as there is no need for gas, oil, and engine to use

this device because it is electric powered. The robotic lawn mower is electric and will not emit

the same emissions as the other gasoline counterparts and eliminates most negative environment

problems.

The group expects that with combining the important technologies the robotic lawn

mower will be able to be controlled with a remote control to be able to mow the yard. The group

will start with an electric self-propelled cord-less mower. Then remote controlled features will be

added to the system. Finally a remote will have to be programmed to operate speed and direction

of the mower.

The final product will be a mower that a consumer would enjoy to use and may even find

fun. They will be able to relax and mow the lawn with ease. The final design for the robotic lawn

mower will be a machine that is effective at mowing, safe to use, and relatively inexpensive.



99 | P a g e

Objective Tree:

Form Final Design

Obtain Software andHardware

Communicationbetween Hardware,

Software, andController

Development of Kill-Switches

Ability to efficientlycut yard

from remote



100 | P a g e

Stake Holders:

A need to consider for the mower project is the funding that will allow for the design to

be implemented. Through Professor Klink, West Virginia University would be the primary

resource for the mower project. Professor Klink, as mentor to the group, has goals for the project

which at first include the ability for the mower to be remote controlled by a user. The goals of

the group and the university (along with Professor Klink) are the same which allows for

solidarity among those invested in the project. However, there is maximum budget allotted to the

project. The members must therefore design carefully to work within this budget. The stake

holders, in this case, West Virginia University will be satisfied with a working prototype of a

robotic lawn mower.

Conclusion:

In conclusion, the task to create a robotic lawn mower that can mow the lawn for a user

can be accomplished by the group first planning to create a mower that can be remote controlled

from one position. The development of the mower will have an assortment of needs and

objectives. The needs consist of safety, reliability, cost efficiency, user friendliness,

effectiveness, and durability.

It is significant to comprehend the background of the lawn mower, using what has

already been done and building upon it can result in a safe and cost efficient robotic lawn mower.

The basics of the ideas behind the current lawn mowers can be used to develop an efficient

robotic lawn mower. The ideas this project focus on are the spinning blade, self-propulsion, and

an electric motor. Ideas that are used in other areas of the market such as remote controlled toys

and GPS systems are also useful for the project.

Finally, the group’s major goal is to fabricate a prototype for a mower that achieves all of

the mentioned specifications. It will be a fully functional remote controlled lawn mower. The

final design for the robotic lawn mower will be a machine that is effective at mowing, safe to

use, and relatively inexpensive.



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References:

(1) "Mower History." The Old Lawnmower ClubCollection, Preservation and Display of Old

Lawn Mowers. N.p., n.d. Web. 29 Feb 2012.


(2) Diggs, Steven. "Corded Vs. Cordless Electric Lawn Mowers." ehow. N.p., n.d. Web. 29 Feb

2012. <http://www.ehow.com/about_6581493_corded-cordless-electric-lawn-

mowers.html>.

(Diggs)

(3) "Riding or Push Lawn Mower – Which One Should You Get?." Lawn Mower and Trimmer

Reviews. N.p., 07 11 2011. Web. 29 Feb 2012. <http://www.lawnmower-



(4) "Lawn mower robots are Coming Out of the Garages of Hobbiests and Into

Businesses.." Robots and Androids. N.p., n.d. Web. 29 Feb 2012. <http://www.robots-

and-androids.com/lawn-mower-robots.html>.

("Robots ")

(5) "Robotic Lawn Mowers." Super Lawn Mower . N.p., n.d. Web. 29 Feb 2012.

<http://superlawnmower.com/category/robotic-lawn-mowers/>.

("Super Lawn Mower")



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Colleen Morgan

Figure 14: [4]

M o n

d a y ,

A p r i l 9 t h ,

2 0 1 2



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BACKGROUND RESEARCH

PAPER

Prepared By: Colleen Morgan



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ABSTRACT

Ever since the 1830s when Edwin Budding created the first lawn mower, the lawn

mower has became an everyday item for almost everyone across the world. It started out as

something simple and has spiraled into several complex forms, always with the original concept

of mowing grass aimed towards in these different forms. [7] As it is known, technology today

will become history tomorrow. Engineers, Designers, Research Analysts and many others

always think of ways to improve the lawn mower. In today’s world, there are several forms of

the lawn mower. People commonly use this device in the form of the gasoline mower using

both the riding and the push versions, the electric mower, and the old push powered version,

but that is quickly dying out. All three common forms have an extremely large similarity, each

of them cut grass. However, it is much more complex than that. These types have many

different benefits and disadvantages associated with them.

The main objective for the LawnBot group is to design a lawn mower that incorporates

all of the features from various types of lawn mowers, plus more. The group will create a

remote control lawn mower that utilizes each of the benefits, creating a safe, reliable and user

friendly lawn mower. The remote control lawn mower has been designed and built by many

engineers throughout the years. These individuals have created new technical designs and

some have even perfected the art of the remote control lawn mower. There are many

variations of the remote control lawn mower, as people across the nation have attempted to

advance the basic lawn mower by implementing the remote control aspect.



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PROBLEM STATEMENT

After researching the several types of lawn mowers available today, I discovered many

advantages and disadvantages related to each kind. The problem to identify for the LawnBot

group is to design and to create a mower that incorporates the advantages of the other types of

mowers, expunging the disadvantages. The group must find a solution to use the existing

mower, but drastically adjust and modify it for an improved model. This can be indeed

accomplished by using the intentions and reasoning (past efforts) derived from the inventors of

the lawn mower and the designers that have developed it into the form it is today. The overall

goal is to create a remote control mower that is safe, reliable, inexpensive, user friendly, and

lastly effective and durable. An extra part of this design, if time permits, is to use the remote

controlled lawn mower design and form it into a mower that works autonomously.



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BACKGROUND & HISTORY

The past efforts of other people and the different types of mowers available today were

explored, and the advantages and disadvantages of each were compared to form the best

design of the lawn mower. The most commonly used type of lawn mower is the gasoline

powered type. People use the push and riding versions, and they are the two most general

forms of the gasoline powered mowers used today. [1] There are many advantages and

disadvantages that are incorporated to each. First off, both of these mowers are relatively

powerful and mowing time is not restricted, except for refueling them. When using these

mowers, people have full range of movement. A person can direct the mower in whatever

direction they may choose.

When comparing the two however, several differences can be noted, and many positive

differences are related to the riding mower. One of the largest advantages of the riding version

is time efficiency, which consequently means they can be used for much larger lawns. People

are more likely to purchase a riding lawn mower than a push mower if their yard is of a larger

scale. Another contribution to the reasoning of the time efficiency advantage the riding version

has over the push version is the larger size of the blades. [9] The push mower will not be able

to cut as much grass as the riding mower in the same amount of time. In addition, the riding

version will evidently prove to be more powerful for the person running the machine, because

one may get fatigued or weary from using a push mower after a long period of time. The riding

mower is a lot less physically demanding than the push mower, which is exceptionally appealing

to consumers. Additionally, even though the push and riding mowers are both user controlled,

it has been said it is much easier to form straight, neater lines with the riding version than the

push version. Many people take pride in the upkeep of their lawns. Users of the riding mower

are able to attach pieces of equipment that can pick up the grass shavings or can lay mulch or

other types of fertilizer. These pieces of equipment now are becoming available for the push

mowers though. Lastly, the riding mower is also more capable of encountering imperfections

and obstacles of the lawn, such as weeds or thicker grass in a better manner.



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On the other hand, the push mower does have many advantages over the riding lawn

mower. Most consumers determine their purchases based off of two items, the user

friendliness and the cost of the product. The riding mower essentially succeeds with how easy

it is to utilize and makes the experience of mowing more comfortable for the user. However,

the push mower succeeds with the cost. The push mowers leading advantage is the cost, being

very inexpensive. Moreover, the push version is more capable of maneuvering in smaller

spaces. One is certainly able to cut between trees and become much closer in distance to

objects than the riding version. The push mower handles inclines and steeper hills better. The

riding mower is made for relatively flat surfaces, and could tip over if going down an incline

which also presents the concept of safety. The push version is much safer than the riding

version, as it has the ability for automatic shut off. When someone lets go of the mower, it

shuts right off and the blade shuts down. In comparison, the riding mowers can be very

dangerous. A person could become very injured or even killed if the riding mower was to stop

functioning properly or if someone got an article of clothing stuck in one of the many moving

parts the riding mower is comprised of. Some people may also argue the power of the riding

mower could be too dangerous.

Instead of the gasoline powered lawn mower, there is an option for an electric powered

lawn mower. The main advantage with the electric version is the eco-friendly theory. [5] With

the electric mower, less pollution is sent into the environment and the amount of fuel

consumed decreases. [3] Charging the electric mowers is also much cheaper than providing gas

for the gasoline mowers. The electric mower is normally designed like the push mower,

containing many of its key safety features. Simply stated, the electric mower is very cost

efficient, safe, and not harmful to the environment. [2]

After reviewing all of the different types of mowers, the group has decided to design

and create a remote control lawn mower. This mower will have all of the benefits the other

types have, but incorporated into one. Many other engineers and creators have succeeded and

developed excellent quality remote control lawn mowers. But, there are numerous styles

designed less complex as well. The group is using the technology and theories of the 21st



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century to develop their own design of the remote control lawn mower. During the process of

design, the power sources available today will be kept in mind along with the advancement of

hardware and software integration. In addition to using the previous ideas of the lawn mower

in prior forms, the remote control lawn mower will offer the consumer with many different

options and features that are requested today. Upon completion of the remote control lawn

mower, the group has also made plans to make the mower function autonomously, which will

require profound programming experience.



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NEEDS & TECHNICAL DESIGN

Due to several research advancements and technological developments, the lawn mower is

able to advance and progress with a remote control feature. The group will start with using a

self propelled electric mower as the base. Then, the group will be using a remote control

device that the user will employ for steering the lawn mower. In addition, another function the

remote control contributes is the use of kill switches which implement safety advantages.

Through system integration of the hardware and software, the remote control will be able to

communicate with the base of the mower. Using the information presented from the specific

electric mower used, students are able to alter the electric mower to develop the final design.

Using the technological advancements of today, students are able to study the remote control

device and learn how to integrate the two main parts together. Functions from the computer

software, RoboRealm, and different hardware materials will be used to create the remote

control lawn mower. Several needs are initially generated at this point that do require

addressing.

The group wants to create a mower that is first safe, secondly reliable, thirdly cost efficient,

fourthly user friendly, and lastly effective and durable. Starting off with most important need

of safety, students have decided to use the self propelled electric mower as their base. Overall,

students feel that the electric mower is the best fit for the safety aspect. It was previously

defined that the push mowers, much like the electric mowers are very safe. In addition, the

electric version will not emit such harmful types of pollution into the air as the gas version

would. This, in the long run, will provide consumers a safer place to live and breathe in.

Several other features from the design of our mower contribute to the safety, many of them

relating to the remote control. Through the use of the remote control, a person will not be as

close to the lawn mower as they typically would be using the push or riding versions. In

addition, several kill switches and sensors will be developed and built. One sensor will be

created and built on the mower that will automatically shut the mower off if it detects

something that may have come in the way of the mower. A kill switch will be implemented on



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the remote control that the user may utilize if it feels the mower needs to be shut off

immediately. Another important safety feature is the use of boundaries while mowing. The

mower will have sensors that detect when it has traveled out if it’s mowing boundaries. The

mower may then immediately shut off, or alert the user to return the mower back to the

designated boundaries Because of the boundaries, the mower will not be able to “take off” as

some riding mowers have even with their safety features. An additional kill switch or sensor is

going to be created to immediately power down the mower if it were to flip over while on an

incline. Unfortunately, the base of the mower may be “top heavy” due to the additional

interfacing features, so this must be formed.

Second, this mower needs to be reliable. Unfortunately, many people have lawn mowers

that somehow break or malfunction. With the electric mower, one basically needs to

implement the use of electricity. With gasoline mowers, several complications can occur from

the oil changes to the mechanical aspects failing. In addition, it can be very time consuming

just to keep the gasoline mower running at all times. The mower we will create will incorporate

electric to bypass all of the gasoline aspects and tune-ups needed. The functions and

programming created with RoboRealm and integrated with the hardware will not change over

time, providing a consistent, reliable mower. However, every piece of technology will require

maintenance at some point.

Third, the mower needs to be cost efficient. Electric mowers are much cheaper to use than

the gasoline powered mowers. With the continuing rising prices of fuel, the most inexpensive

choice is the electric base mower. In addition, electric mowers do not require the oil filters or

the tune-up costs associated with gasoline power. [3] It has been said, on average, the electric

mowers cost 5 dollars per year to use. [6] Overall, the long run cost of the electric mower is

much cheaper than the gasoline mower.

Fourth, the mower created must be very user friendly and marketable. With the remote

control aspect, mowing the lawn will be effortless to do, like it is with the riding mower. People

will not deal with the strenuous circumstances of pushing a lawn mower, and it will be even

easier to use than a riding mower. A person is able to sit on their deck or porch and mow their



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lawn with the use of their hands. People with disabilities, the elderly, etc. will be able to mow

their lawns in an easier manner. The remote control feature produces countless advantages

than other lawn mowers of today. Given that most people prefer a well kept and neat lawn,

the remote control feature allows the user to not only have control of where he wants to mow

but how precise and straight his mowing lines will be. In addition, the lawn mower that the

group is creating will have a grass catcher bag attached. Because of this bag, the lawn will be

even neater than before. Another desirability of the remote control lawn mower is the sound.

Most gasoline mowers are very loud; where as the electric mowers are quieter. This will be a

large user attraction.

Lastly, the group has to address the need of making a lawn mower that is effective and

durable. The group concluded that using a remote control with the electric mower may not

take as long as to mow an area as it would with a push mower. Because of the remote control,

the user will not get tired and will not slow down. The time efficiency of mowing can be

maintained, for the most part, and because an electric mower is being used, it is known it will

effectively cut the grass similar to before. In addition, the mower the group will be using will be

able to fit into smaller spaces, for example between trees. Because it can fit into smaller

spaces, it is able to effectively cut more of one’s lawn than the riding versions do, with less

weeding and trimming work.



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OBJECTIVES

Many objectives have been developed to carry out the creation of the remote control

lawn mower. The objectives and intentions have been established and broken down in order

for specific developments to be achieved starting with the final design. The final design of the

remote control lawn mower must be accomplished first and foremost. Background information

of the specific mower we implement with the software will be researched to understand its

parameters. The rest of the hardware, including the means of communication between the

remote control and the mower will also be researched and designed. The remote control

characteristics and features need to be set as well. Starting off with how wide the range will be

for the lawn mower to still recognize the remote control. In addition, the toggle switches of the

remote control need to be defined for the turning and propulsion of the mower.

After the final design is completed, the hardware and software will be obtained. The

parts will be ordered, and the programming will be written for the software portion. Some

programming may also be written for the design objective. It will need to be known how the

remote control will interact with the mower, so the programming may be previously done.

The third main objective is creating the communication between the software and

hardware. At this point, the group will need to utilize all of the vast information they have

found to integrate the hardware, software, and remote control. This will possibly be the

longest and most challenging objective to accomplish, as much troubleshooting and testing will

be done to see if the remote control and mower are communicating properly.

The further main objective will be the development of the kill switches. The first kill

switch created will employ the use of the automatic shut off. After hitting a button or releasing

something on the remote control, the mower will immediately power down. These are for

safety purposes. In addition, a kill switch will be created in case the mower tips over. The last

main objective will be the true test if the remote control lawn mower can efficiently and

effectively cut the yard from the remote.



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Many other objectives have been created if time permits. Some of these are designing

another kill switch if the mower goes out of certain boundaries. In addition, the group would

like to see the mower decrease power consumption with the knowledge they have developed.

Furthermore, another great objective or goal would be placing a senor on the mower. This

senor would then detect if any items have came in its way, such as cats or dogs. The sensor

would stop the mower upon the detection of an object and would another great safety feature.

Lastly, the group would like to create a zero turn element of the mower. Because of this, the

mower would immediately turn as it needs to, not driving over any other part of the grass. This

would be a great characteristic for the people who take pride in their lawns.



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TECHNICAL & ADAPTIVE CHALLENGES

With the complexity of the project, the group will face several challenges throughout

the design and manufacturing processes. As the design process has been under way since the

start of February, one of the largest challenges encountered has been understanding the

limitations and range of the computer software, RoboRealm. This is difficult due to

inexperience with the software. Because of this, it is hard to prepare the functions and their

parameters and roles within the project. Otherwise, the majority of the challenges we will face

will pertain to the mower and remote control communicating properly. There will be two

servos placed on the mower connected to the wheels so the remote can accurately steer it.

This will be one of the largest challenges faced, because the servos need to be placed in such

precise positions. In addition, adding the motor control equipment and receiver will also be

quite the concern. A large enough power supply, the battery, will need to be determined and

implemented for the motor control and receiver. Without the receiver, the remote control will

be unable to communicate with the remote control. Forming the connections between all of

the equipment, the actual mower itself, and the wheels could also present a large technical

challenge. Several tests will be performed to troubleshoot the several challenges described in

order to produce the safest, most reliable, and user friendly mower.



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STAKEHOLDERS

When designing and manufacturing this project, many different people will need to be

taken into consideration. For starters, the main stakeholder will be the person or persons

supplying the funds. These people are expecting a functioning, safe lawn mower, certainly not

something that doesn’t perform accurately or is frequently broken. Sponsors wouldn’t want to

spend money on something that doesn’t eventually operate. The mentor of this project is also

expecting a fully effective, working remote control lawn mower with the probability it will

function autonomously, as he has invested a great deal of time into this project.

There are many other stakeholders that are related to this project. These are the people

that will be affected negatively by a remote control or autonomously functioning lawn mower.

Many people’s incomes are based off of selling or building older versions of lawn mowers. If

the lawn mower this group is creating turns out to be very successful, many people could

potentially wish to purchase it. They would be replacing their old lawn mowers with this one,

or even purchasing ours from the start. Eventually the older versions of lawn mowers would

die out, causing many people to lose their jobs.



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CONCLUSION

The remote controlled lawn mower provides the user with many benefits, and

therefore could someday become a very profitable and marketable technology. However, most

consumers are not aware of this advancement of the lawn mower. This group is utilizing each

benefit of the previously designed lawn mowers and incorporating them into a new design of

the mower that integrates a software and hardware for the use of a remote control. The safety

features, reliability and cost efficiency, and the user friendliness of the mower designed will

succeed the benefits of some other mowers that are present today. The group will use the

knowledge they have gained over the years and employ it to create a lawn mower that will

undoubtedly be a successful and important piece of technology.



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REFERENCES

1. "Brand Reliability." Consumer Reports Buying Guide (2005): 327-337. Academic Search Complete.

Web. 9 Apr. 2012.

2. "Electric Lawn Mowers." - Finding the Right Electric Lawn Mower . Web. 09 Apr. 2012.

<http://www.lawnmowersworld.com/electric/>.

3. Hollis, Scott. "Cordless Electric Lawn Mowers." Mother Earth News 209 (2005): 67-70. Academic

Search Complete. Web. 9 Apr. 2012.

4. "Remote Control Lawn Mower - Diesel Bombers." Diesel Bombers. Web. 9 Apr. 2012.

<http://www.dieselbombers.com/bomb-shelter/15946-remote-control-lawn-mower.html>.

5. "Riding Lawn Mowers: Gasoline Vs. Electric." Essortment . Web. 09 Apr. 2012.

<http://www.essortment.com/riding-lawn-mowers-gasoline-vs-electric-54895.html>.

6. "Riding or Push Lawn Mower â € “ Which One Should You Get?" Riding or Push Lawn Mower Which

One Should You Get? Web. 09 Apr. 2012. <http://www.lawnmower-reviews.com/riding-or-push-

lawn-mower-which-one-should-you-get>.

7. Roman, Harry T. "Lawn Mower Makeovers." Technology Teacher 67.8 (2008): 19-21. Academic

Search Complete. Web. 9 Apr. 2012.

8. "Types of Pollution Emitted by Gas Lawn Mowers..." Reel Mowers Push Reel Mowers on Sale at

Ecomowers.com. Web. 09 Apr. 2012.

<http://www.ecomowers.com/Types_of_Pollution_a/121.htm>.

9. "When Should You Use a Push Mower Vs. a Riding Mower?" Riding Mower Vs. Push Mower . Web. 09

Apr. 2012. <http://www.lawncare.org/push-mower-vs-riding-mower/>.



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Erin Radtke

Robotic Lawn MowerEE 480 Senior Design

Erin Radtke

4/9/2012



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Contents

Abstract ..................................................................................................................................................... 120

Background ............................................................................................................................................... 122

Problem Statement ................................................................................................................................... 124

Needs and Goals ....................................................................................................................................... 129

Future Needs and Goals ............................................................................................................................ 130

Objectives and Expected Outcomes ......................................................................................................... 132

Conclusion ................................................................................................................................................. 134

Works Cited ............................................................................................................................................... 135



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Abstract



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Mowing the lawn with a standard motor powered lawn mower is an inconvenience, and

no one takes pleasure in it. Cutting grass cannot be easily accomplished by elderly, younger, or

disabled people. Motor powered push lawn mowers and riding lawn mowers create noise

pollution due to the loud engine, and local air pollution due to the combustion in the engine.

Also, a motor powered engine requires periodic maintenance such as changing the engine oil.

Even though electric lawn mowers are environmentally friendly, they too can be an

inconvenience. Along with motor powered lawn mowers, electric lawn mowers are also

hazardous and cannot be easily used by all. Also, if the electric lawn mower is corded, mowing

could prove to be problematic and dangerous. Designing a prototype that would make cutting

grass less physically demanding and enjoyable would interest many consumers. This machine

would be valued by someone who has grass allergies, handicapped or disabled, or is not

capable of mowing the lawn themselves. This machine will cut the lawn entirely with minimal

assistance and labor.

The solution is a robotic lawn mower. Not just any robotic lawn mower, a self-propelling

electric remote control lawn mower. The goal is to create a lawn mower that can be operated

with minimal effort. The approach in constructing this lawn mower consists of two part

procedures. The first step requires creating a lawn mower that can be controlled by the user

with a remote control. The second step requires automation of the mower in which the user

can program an area for cutting where the mower will accurately cut the region requiring little

assistance. When the first step in the design process is completed, the design will require the

incorporation of the components to make the mower fully autonomous testing. The price of

this design will be in the range of regular push lawn mowers to be appealing to consumers. The

primary goal is to create a machine that is reliable, or there will be no beneficial factors for the

consumer. The prototype must have safety features because of the equipment being used such

as a spinning mower blade. The purpose of this design is to re-create a lawn mower that

incorporates present time technology.



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Background

The lawn mower was invented in 1830 by an engineer named Edwin Beard Budding.

Budding obtained the idea of the lawn mower after seeing a machine in a local cloth mill which

used a cutting cylinder mounted on a bench to trim cloth to make a smooth finish after

weaving. Budding then realized that a similar concept would enable the cutting of grass if the

mechanism could be mounted in a wheeled frame to make the blades rotate close to the lawn's

surface. This realization led Budding into partnership with a local engineer, John Ferrabee to

produce lawn mowers made of cast iron. Like Budding’s idea, these lawn mowers featured a

large rear roller with a cutting cylinder in the front. Cast iron gear wheels transmitted power

from the rear roller to the cutting cylinder (1 "Old Lawnmower ClubCollection, Preservation and

Display of Old Lawn Mowers").

Nowadays, lawn mowers are useful pieces of machinery that employ a revolving blade

to cut a lawn at a smooth, even length. Since Budding’s original design of the lawn mower,

there have been various lawn mower designs that have been designed and created. These



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designs include a push lawn mower, which is suitable for smaller lawns, and the ride-on

mowers, which are capable to cut grass in larger lawns (1 "Old Lawnmower ClubCollection,

Preservation and Display of Old Lawn Mowers"). Other more recent models of the lawn mower

contain corded and cordless electric power. Cordless electric powered lawn mowers are

powered by 12 volt rechargeable batteries. Cordless mowers have the maneuverability of a

gasoline powered mower and the environmental friendliness of a corded electric lawn mower

(3 Diggs).

The latest design of the lawn mower is the programmable robotic lawn mower. A

programmable robotic lawn mower is a lawn mower that is designed to mow a lawn

automatically, without any need for human involvement or interaction. The programmable

robot lawn mower can be programmed with a variety of information which is utilized to mow

the lawn regularly due to the user’s timely schedule. The lawn mower can also be programmed

to mow grass at the desired height. The mechanism of a robotic lawn mower contains wheels

which allow the lawn mower to navigate the lawn, along with sensors which are used to detect

changes in terrain, fences, and other foreign objects which should not be mowed. Some of

these robotic lawn mowers are equipped with sensors which can interface with other sensors

installed around specific areas to control the robotic mower to stay within its boundaries of the

lawn. Typically, the robot includes a charging station which can be installed anywhere where

there is an electric outlet. Some robotic lawnmowers are solar powered, charging up as they

mow the grass. Most of these robots are equipped with containers for clipping collection so

that the lawn does not need to be raked after mowing (4 "Robots ").



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Problem Statement

The problem presented to our group is that there are benefits and drawbacks in using

each lawn mower that has been designed and created. The original push lawn mower, that is

motor powered, is considerably less expensive than any other lawn mower design. One who

owns and uses a standard motor powered push lawn mower understands that another benefit

is maneuverability. It is easier to maneuver and get close to trees and other permanent or large

obstacles with a push mower. However, the standard motor powered push lawn mower is not

considered user friendly. People who are younger and who are older would have issues using a

typical push lawn mower. Also, people who are handicap, or people who are disabled are not

able to use a standard push lawn mower in which case, this lawn mower is not efficient. The

most obvious drawback to a push mower is that it is going to take much more time to mow a

large area with this type of mower. There are a couple of reasons for this. One is because the

deck size and the length of the blades in a push mower is a lot smaller. With shorter blades one

will not be cutting as much grass at one time and will have to make more passes to cut the

same amount of grass. Another drawback when using a standard motor powered push lawn

mower is that this lawn mower is not environmentally friendly. This standard push lawn mower

requires the use of gasoline, oil, and an engine. With this in mind, there is noise pollution

caused by the loud engine. This typical motor powered lawn mower uses gasoline which has

the potential to pollute the local environment and will emit harmful emissions (2 "Lawn Mower

and Trimmer Reviews").

Another lawn mower design, the riding lawn mower, also has some obvious benefits

and drawbacks. A riding mower is considerably more expensive than the standard motor

powered push lawn mower which is a drawback. Also, the riding lawn mower is not nearly are

maneuverable as the standard motor powered push lawn mower. Along with the standard

motor powered push lawn mower, the riding lawn mower also is not environmentally friendly.

This riding lawn mower is motor powered which also requires the use of gasoline, oil, and an



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engine. This causes noise pollution and harmful greenhouse gas emissions released polluting

the environment. A benefit to owning and using a riding lawn mower is that one who uses a

riding lawn mower will get the job done a lot faster. The motor powered riding lawn mower has

a more powerful motor and has a larger cutting deck. Another benefit of a riding mower is that

it is a lot less physically demanding. One does not have to walk around their yard pushing the

mower and it does not take a lot of physical effort to drive a riding mower around a yard.

Another benefit of a riding mower is some of the attachments that are available for many

models (2 "Lawn Mower and Trimmer Reviews").

Unlike both the standard motor powered push lawn mower, and the motor powered

riding lawn mower, the electric lawn mower is environmentally friendly. There is no need for

gasoline, oil, or an engine to use the electric lawn mower because it is powered electrically.

With this said, there is no noise pollution due to engine noises, and no fumes. The motor

powered push lawn mower, and the motor powered riding lawn mower uses gasoline and has

the potential to pollute the local environment. A drawback to owning an electric lawn mower is

that they are expensive. This is so because the electric lawn mower replaces the engine with

electrical components so wherever there is electricity, one will be able to operate this lawn

mower. Another drawback in using an electric corded lawn mower is that an electric lawn

mower cannot be attached to an extension cord that is longer than seventy-five feet. This is

because the motor will take an extreme power dip that causes the blades to barely spin. Corded

electric mowers are limited in range by their trailing power cord, which may limit their use with

lawns extending outward more than one hundred to one hundred-fifty feet from the nearest

available power outlet. There is the additional hazard with these machines of accidentally

mowing over the power cable, which stops the mower and may put users at risk of receiving a

dangerous electric shock (3 Diggs).

The most recent lawn mower design is the programmable robotic lawn mower. The

robotic lawn mower is an electric lawn mower that does not require manual labor and can be



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programmed with a variety of information which is utilized to mow the lawn on a regular

schedule. The lawn mower can also be programmed to mow grass at the desired height. The

mechanism of a robotic lawn mower contains wheels which allow the lawn mower to navigate

the lawn, along with sensors which are used detection of foreign objects. The robot lawn

mower is environmentally friendly and unlike gasoline powered lawnmowers, robotic

lawnmowers are very quiet. With this programmable robot lawn mower one can mow their

lawn during the night time. Night time operation is also used at locations like golf courses, so

that golfers can enjoy the course at all times during the day. There are a number of reasons to

use a robotic lawn mower. It is user friendly, safe to use, efficient to use, and environmentally

friendly. However, this programmable lawn mower is very expensive. One can pay upwards of

$4,000 to purchase their own. These lawn mowers are very expensive because they have some

many capabilities such as rain sensors, and safety sensors. Another drawback is that this lawn

mower requires the user to set up a border wire around the lawn that defines the area to be

mowed. This timely process is must also be done correctly or else the robotic lawn mower will

not operate properly (4 "Robots ").

The problem presented here is that there are benefits and downfalls to each lawn

mower that has been designed. Our main goal is to design and create a lawn mower that

incorporates all of the benefits of the previous mentioned lawn mowers and eliminate all of the

previously mentioned drawbacks. With all of these lawn mower designs mentioned, our plan is

to create a self-propelled electric robotic lawn mower with remote control capability.

The design of this lawn mower will mow grass autonomously. The problem given to the

group is to create a mower that is remotely controlled by a user and then takes that existing

design and adapts it to work autonomously. The first stage of the design is to prepare the setup

for the automation side of the project. When designing a lawn mower with a full functionally

remote control, the requirement remains testing maneuverability with the main controls. When



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the remote control mower is created, one can incorporate more components such as sensor

capability, gps, and computer interface that will work with the autonomous functionality.

Other robotic lawn mowers require electric wire to create a mowing boundary for the

machine. However, this type of design is very temperamental, if the electric line is not properly

placed, the mower could potentially leave the designated boundary. This type of robotic lawn

mower design involves tedious programming, and software design, and a buried guide fence

which can make testing more difficult. Our design will be more hardware set with software

controls while still maintaining the efficiency and reliability of regular lawn mower. The primary

objective is to create an autonomous mower that is very simple to use, effective, and efficient

as well as incorporating safety, and simplicity inexpensively.



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Needs and Goals

Due to the various amount of technological developments, the lawn mower will have

remote control capability. The lawn mower design starts as a self propelled electric mower as a

primary building block. A remote control device will be incorporated in order for the user to

have full steering control. Using system integration with hardware and software, the remote

control will communicate with the self propelled electric mower base. Once enough

information is gained by operating, one can adjust the electric mower to develop the final

design. Hardware is a key feature in building this lawn mower for final operation. Along with

hardware, software will be incorporated for the communication from the remote control to the

mowers wheels.

In order to start building this prototype, one must design and have the design finalized. In

which case, the remote control lawn mower design much be fully accomplished before any

building takes place. One must also obtain background information of the specific mower that

will be implemented with the software. The remaining hardware and software tasks include

applying communication between the remote control and the mower. The design of remote

control and the necessary capabilities will be needed as well. Focusing on range, and distance

for communication between the device and controller is another task that must be completed.

Along with remote control design and integration, the toggle switches on the remote control

must be defined in order for the lawn mower to receive power.

Once these tasks have been completed, the hardware and software will be physically

integrated. The necessary parts and equipment will be ordered, and the programming will be



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written for the software portion. The programming will include remote control interaction with

the mower.

The next necessary task includes creating the form of communication between the

software that was programmed, and the mowers base hardware. This process involves various

steps of troubleshooting and testing in order for the remote control and the lawn mower to

communicate.

For safety purposes, it is a necessity to develop kill switches. A kill switch is a switch

that turns the device off when the device should not be running. For instance, if the lawn

mower tips over, it is important that the lawn mower turns off automatically. In which case, the

primary kill switch created will engage automatic shut off. A primary goal and a definite need is

that a user will be able to hit a button or switch on the remote control, and the mower will shut

down. The final necessity is that the user has full control over the remote, and the lawn mower

can cut the lawn in an efficient manner.

Future Needs and Goals

There are many other needs for this lawn mower that have been created if time

permits. Another goal is to design another kill switch for location purposes in which case if the

lawn mower loses communication with the remote control and goes outside its boundaries it

will automatically shut down. Also, another innovative task involves integrating sensors to the

mower for safety purposes. The purpose of that sensor would stop the mower upon the



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detection of any foreign object. Furthermore, another feature would include applying a zero

turn feature to the mower. With this advancement the mower would have the capability to

sharply, and immediately turn as the user controls. Smaller, and simpler tasks such as

incorporating a collection container to collect grass clipping after the user mows is also another

advancement based on if time permits.



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Objectives and Expected Outcomes

There are a number of reasons to use a self-propelling remote control

robotic lawn mower. It can save significantly on labor costs, whether one is maintaining

commercial landscaping or paying the neighbor kid down the street to mow the lawn. Many

people really dislike mowing the lawn, so making a robotic lawn mower will be a welcome

addition to the arsenal of lawn care tools. Our expected outcome is to create a remote control

robotic lawn mower that is user friendly, cost efficient, safe to use, efficient to use, and

environmentally friendly.

The robotic lawn mower that we plan to design will be user friendly for everyone. The

primary goal is to allow both a younger and older person to be able to use this device. Along

with the various ages of users, this lawn mower can also be used by people who have

disabilities and are unable to use a regular push, or riding lawn mower. Also, people who are

allergenic typically are not able to mow their lawn with a standard lawn mower. With this

remote control robotic lawn mower, people with allergies will still be able to mow their lawn.

Because the user may stand at a certain distance away to mow the lawn, there is less risk of

allergenic symptoms.

The prototype will also be automatic and will run on a charged battery with no cords to

interfere with operation. Because the self-propelling robot lawn mower is used to operate with

a remote control, each user will be able to have hands on control of the yard work as the job

takes place. “The idea behind the device is to allow the lawn mower to do all the hard work,

http://www.wisegeek.com/what-is-landscaping.htm

http://www.wisegeek.com/what-is-landscaping.htm



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while the operator pulls the strings behind the curtain” ("Super Lawn Mower"). Typical gas lawn

mowers are notoriously hard to start. With the remote control capability, and automatic start

up, anyone can mow their lawn exactly when they want and how they want simply by pressing

a button and using the remote controller. The automatic start up will make stopping and re-

starting easier than the standard lawn mower.

One of the expected outcomes is to be able to design a cost efficient robotic electric

lawn mower. Robotic lawn mowers cost roughly $4,000. The expensive price is due to the

sensor capability. The plan is to use a cordless electric lawn mower and incorporate remote

control capability which will be less expensive than a robotic lawn mower with sensor

capability.

This robot lawn mower design will be safe to use. With its remote control capability the

lawn mower stays within the boundaries of the lawn because the user is able to have fun

control over the lawn mower with the controller. With that said the user will also be fully

responsible for the lawn mower.

The expected outcome is also to create a robotic lawn mower that is more efficient than

the standard lawn mower. Because of the robotic lawn mowers electric capabilities, the lawn

mower will be much quieter versus the standard motor powered lawn mower. The robot lawn

mower will also be cordless which will be a main advantage for using this type of mower. A

cable or cord may restrict how much the lawn mower can mow, since it has to be attached

constantly to a power source. This cordless electric robotic lawn mower will not have this

problem and can be used on medium to large sized lawns. With a cord, one must continue

checking where the cord is, and to be careful not to mow over it.

This prototype will also be environmentally friendly. There is no need for gas, oil, and

engine to use this device because it is electric powered. With this said there are no loud engine



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noises, and no fumes. A typical motor powered lawn mower that uses gasoline has the

potential to pollute the local environment. This robotic lawn mower is electric and will not emit

the same emissions as the other gasoline counterparts thus, eliminating the need for

greenhouse gas, oil, and gasoline.

In this case there are people who will be affected by the remote control robotic lawn

mower. Small lawn and landscaping businesses may be affected, for they may not be receiving

as much profit or demand if people start purchasing and using this prototype. Lawn companies

that mow public venues such as golf courses, and recreational areas may suffer if these venues

decide to purchase the remote control robotic lawn mower. West Virginia University will be

affected as well because they are funding our prototype for our senior design project

graduation requirement.

Conclusion



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Mowing the lawn can be an inconvenience. The standard motor powered lawn mower

is not easy, safe or efficient to use. It also is not environmentally friendly causing local pollution,

and is very noisy. The fact is that no one enjoys mowing the lawn. It cannot be easily used by

elderly, younger, or handicap people. Motor powered push lawn mowers also require periodic

maintenance such as changing the engine oil. Electric lawn mowers are also an inconvenience.

Unless your power outlet is close enough to the lawn, mowing could prove to be problematic.

Also, the standard robotic lawn mowers which would resolve these issues, is far too expensive,

and some of these mowers still are not reliable. The solution is a self-propelling electric remote

control lawn mower. It is cost efficient, user friendly, efficient for use, safe for all users, and

environmentally friendly.

Works Cited

(1) "Mower History." The Old Lawnmower ClubCollection, Preservation and Display of Old LawnMowers. N.p., n.d. Web. 29 Feb 2012.


(2) "Riding or Push Lawn Mower – Which One Should You Get?." Lawn Mower and Trimmer

Reviews. N.p., 07 11 2011. Web. 29 Feb 2012. <http://www.lawnmower-



(3) Diggs, Steven. "Corded Vs. Cordless Electric Lawn Mowers." ehow . N.p., n.d. Web. 29 Feb

2012. <http://www.ehow.com/about_6581493_corded-cordless-electric-lawn-

mowers.html>.



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(Diggs)

(4) "Lawn mower robots are Coming Out of the Garages of Hobbiests and Into

Businesses.." Robots and Androids. N.p., n.d. Web. 29 Feb 2012. <http://www.robots-

and-androids.com/lawn-mower-robots.html>.

("Robots ")

(5) "Robotic Lawn Mowers." Super Lawn Mower . N.p., n.d. Web. 29 Feb 2012.

<http://superlawnmower.com/category/robotic-lawn-mowers/>.

("Super Lawn Mower")



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David Smith

EE 480 – Senior Design Project

Robotic Lawn Mower

Spring 2012

David Smith

Partners: Zachary Taylor, Erin Radtke, Colleen Morgan, Corey Kimble

Advisor: Dr. Powsiri Klinkhachorn



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Date Submitted: 2/29/2012

Part 1 – Abstract

The Robotic Lawn Mower is a senior design project that incorporates the machinery of a

modern electric, self propelled lawn mower to the electromagnetic technology of a remote-

controlled car. This integration of technology would be used to have the lawn mower controlled

remotely from a safe and comfortable area. While cutting out the danger of lawn mowing

accidents, adults could mow the lawn from the inside of a porch or under shade rather than out in

the sun under extreme heat or sun exposure. The child of said adult could control the remote

from a safe distance and mow the lawn without the danger of modern lawn mowers. Even still, a

handicapped individual could finally have a method of mowing the lawn using a remote control.

This product would have to be safe, reliable, cost efficient, and user friendly. The safety

of the Robotic Lawn Mower would come from the fail-safes built into the remote control and on

board of the mower to simulate the already implemented fail-safes on modern lawn mowers.

The Robotic Lawn Mower would also have to be just as reliable as the modern electric, self-

propelled lawn mowers on the market today, but cheaper. Lastly, it would be essential that the

remote would be extremely easy to use to ensure constant visual contact with the lawn mower

without looking down at the remote.



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For this to be satisfactory, the group must finalize a design, implement and integrate the

hardware and software, and complete full testing of cooperating systems. This process would

take several months including a new education behind programming transmitters and remote

controls. After completion of the prototype, testing would be involved to ensure satisfactory

results for lawn height, remote signal, device turning, and final price of the finished product.

This device would create a different philosophy behind the lawn mowing process. Adults

would not view the chore in such a bad light and would not view it as dangerous for children

from a safe distance. Handicapped individuals could benefit greatly from this and it could cause

a wave of new products for handicapped individuals to have more comfortable lives.Landscaping businesses would spend less time on labor, which would mean fewer jobs in the

landscaping industry. With this knowledge, the labor would shift to other parts of society that

need labor. Overall, this product would be beneficial to all parties and would raise the quality of

life for the average homeowner.



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Part 2 – Problem Statement

The selected project concerns the construction of a remote control lawn mower. The aim

of this project is to give the consumer the ability of mowing the lawn without having to move

from a chair on a porch or deck whether this is due to the desire to stay in the shade away

uncomfortable weather situations (such as extreme heat or sun) or to the inability to mow the

lawn by themselves i.e. a handicapped individual. This way, one can enjoy a comfortable

environment while completing a chore that has been notable since the 19th century.

The goal for this project is to create a lawn mower that can be operated with little or no

effort to the user. This can be accomplished in numerous ways, but the group has design a two-step approach. The creation of a lawn mower controlled by the user via remote control is the

natural first action. The second step will be to automate the mower so the user can program a

cutting area and, thus, the mower will successfully and precisely cut the designated area with no

assistance.

This device is to cut a grass lawn with the efficiency of normal, household lawn mower.

The automated lawn mower is to be on par in cutting efficiency, cutting height adjustments, and

in overall safety with any other lawn mowing machine on the market. That being said, lawn

mower such as the blade, the motor that spins the blade, or the battery that powers the motor will

not be manipulated during the construction of this machine. The specific modifications that will

be made to the original lawn mower shall be the two levers that are on most lawn mowers, the

kill switch and the self propelling lever. These two levers will be removed and the cords along

with them to electrically signal the mower to have a kill switch function and to propel the

wheels. These controls will be received by a transmitter on the lawn mower and will be sent by

the remote control in the user’s hands.

The remote control should have the ability to control the lawn mower from 25 yards with

controls such as: power, direction, speed, emergency shut off or “kill switch.” The remote

control is to be user friendly in the sense of simple controls and easily handheld. With this in



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mind, the power function to the mower should just be a simple on/off switch. The direction and

speed is to be input using a toggle or “joystick” that is not only an input for of north, south, east,

or west, but the farther in that direction, the faster the mower will go. Lastly, the emergency shut

off or “kill switch” can be a number of things including a trigger that must be constantly held

down for the blade to turn.

The design of the device is a major portion of the success of this project. The integrated

hardware on to the initial lawn mower will be placed on top of the motor that spins the blade.

The two wires that go with the kill switch and self propelling levers will be rerouted and

designed to be activated by the integrated hardware from a signal via the remote control. The

receiving transmitter and the switches for the replaced levers will have to be powered by a battery that is separate from the initial lawn mower battery. That being said, the internal

circuitry for the starter of the original lawn mower will have to be rerouted from being a switch

on the frame to be signaled from the remote. Along with this, the movement of the lawn mower

will need to be automated rather than the original design of being lead on by a human behind the

machine. With this, two servo wheels will need to be attached to the mower so the remote

control can steer the device. In order to fully grasp the focus of this project, one must understand

the history of the evolution of lawn care and how the invention of the lawnmower was first

realized.



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Part 3 – Background

The history of cutting grass goes beyond very much beyond present times back to the

ancient Romans when they used the iconic scythe ([1] Smith). In fact, the scythe was used until

1827 when Edwin Budding, an English engineer, developed the idea of an actual lawn mower

after observing a cloth mill machine which used a bladed reel to give a smooth finish on the cloth

([2] Passmore). This device was used to cut the grass for sports facilities such as cricket, polo,

soccer, rugby, and tennis along with rather large gardens. From this, the British patent was

granted in 1830. With this, Budding and his partner John Ferrabee granted permission to

competing companies to developing other mowers. In 1859, Thomas Green invented the first

chain-driven mower and manufacturing continued throughout the 1860s. Other modifiedversions continued to be developed along with the human-pushed mower, rotary blade mower,

and in 1902, Ransomes came out with the first commercially available mower powered by an

internal combustion gasoline engine ([3] The Old Lawn Mower Club). This became the norm

until the 1930s when C. C. Stacy started to develop the electric lawnmower. Although the

electric lawn mower came about in the 1930s, it did not catch on until much later ([4] Electric

Lawn Mower).

Also relevant to this project would be the background behind the remote control

technology. The infamous Nikola Tesla can be credited to developing one of the earliest

examples to the remote-control in 1898 where he controlled a boat calling it teleautomation.

This technology spread through Europe and across the world and eventually, in the 1930s, lead

to the first remote controlled airplane. It was not until the 1950s when we first saw the television

remote control that we are accustomed to today ([5] Jonnes).

The combination of the two has been on the market for a few years now. Unfortunately,

the price on these devices is much too high for the average American consumer. As shown on

Brookstone.com, the selling company asks for $2,499 for a product similar to the one that we are

developing. This price must be more suitable to the American consumer wallet to be taken

seriously as a strong and healthy product ([6] Robolawn). Even more importantly, the price must



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be in the range of the aimed consumers of this project: the average American family who need

not spend time on such chores and the handicapped who are unable to carry out such landscape

labor tasks such as lawn mowing.



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Part 4 – Project Influence

The Robotic Lawn Mowing device would be revolutionary to the way homeowners

would go about their weekends. Instead of viewing the lawn mowing experience as a hassle, this

could be an entertainment source similar to a video game. An adult could have the same

experience that a child on Christmas morning has with a remote controlled car. Average adults

would take the time to mow the lawn from the comfort of a porch rather than walking in the

sweltering heat. Even still, the parents could have their children mow the lawn using the remote

with minimal safety hazard to the child itself. Many of the downfalls of the modern lawn mower

and children is the respect you must pay to a large, high speed blade consider the distance of two

yards from ones legs including the sheer four foot size of the handles. A child could control theremote with being an adequate distance away from the mower’s blade.

An additional way that this product would be revolutionary would be to the landscaping

companies. This would require less labor and possibly faster lawn cutting. This would

eventually cause fewer jobs available in the landscaping business, but this would help the

American economy otherwise because that labor could be used elsewhere.

Last but certainly not least, a very significant part of why this machine would be

revolutionary would be that it is handicap accessible. An individual in a wheelchair would have

a very hard time mowing the lawn with the modern products on the market, but this would give

them a way to control the device as any other non-disabled person. This could start a trend of

new products across our livelihood that are based around being handicap-accessible. With these

focus groups in mind, the product must be satisfactory on several areas that directly affect the

targeted consumers.



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Part 5 – Project Essentials

The Robotic Lawn Mower has several areas that must be addressed to be considered a

success. These areas would determine the success of the project from the perspective of this

design group, West Virginia University, and the consumer. After a number of group discussions,

the six main focus areas to make this device a success would be: safety, reliability, cost

efficiency, user friendliness, effectiveness, and durability.

Safety, as always, should be each and everyone’s top priority regardless of the subject

matter. In this design project, the Robotic Lawn Mower should not only focus on the safety of

the user, but of others that could be in the immediate area of the device. Due to the fact that this

project is based on a machine that rotates a blade at high speeds, safety is of particular interest.

On most lawn mowers in the market today, they contain a kill switch lever that must be kept

down in order for the motor to rotate the blade. This fail-safe system is nicknamed a “dead

man’s switch” for the literal sense of if the operator becomes incapacitated through death or loss

of consciousness, the switch is tripped and the machine automatically loses power. On the lawn

mower that we will use for the project, the handle that would be held down while a human would

be behind the original mower must be modified to be controlled remotely.

Along the same lines, there have been many recorded accidents of the conventional stand

up lawn mowers or riding mowers having flipped over due to an incline. This predicament

would usually cause the operator to release the fail-safe handle on a conventional lawn mower,

thus shutting off the power. If the Robotic Lawn Mower was to have become upside down for

any reason, the system must immediately cut power to the motor to avoid having an open blade

running free toward anything other than the ground. To avoid a situation like this, an

accelerometer will be installed to sense the orientation of the motor because of direction of

weight changes similar to how a cell phone can sense whether its orientation is portrait or

landscape.

The second focus area of this project would be the reliability of the Robotic Lawn

Mower. This area would describe, in short, if the consumer would have the same satisfactory



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While aiming for these project essentials, the team must focus on several milestones to achieve

said essentials for the product to be successful.



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Part 6 – Project Objectives

With the needs of the project drawn out, the senior design group of the Robotic Lawn

Mower can be separated into five major milestones. These milestones are used to not only track

the progress in the project, but to estimate the amount of man-hours that this development will

demand. These goals are in chronological order in the sense of without every part of the

previous milestone, the next milestone cannot begin.

The first milestone facing the Robotic Lawn Mower team is the final design of the

device. This includes the exact electric lawn mower that will be purchased and used along with

the remote control, transmitter, battery, and other circuitry elements.

The decision must be made to include the “zero-turn” capability of the device. This

would incorporate two independent axles to move rather than one for a front or rear wheel drive

design. These two independent axles would enable the device to execute the 90 degree turns that

operators of lawn mowers face when it comes to obstacles like fences or trees. This would also

enable the lawn to be mown in a straight pattern rather than forcing a two-point turn and creating

circular patterns along the edges. To effectively use the two axles, there would need to be four

servo wheels and a large amount of programming to support the independent axles.

Obtaining the hardware and software of the device would be the second milestone of the

group. This ranges from the selection of the individual items needed to incorporate to the

purchasing of said items either through West Virginia University or personal funds of group

members. This milestone on the hardware side requires patience and research.

Concerning the communication between the mower and the remote control, programming

the transmitter along with the design website will be a challenge for a group of all Electrical

Engineering majors. Without a firm background in upper level Computer Science classes, the

Robotic Lawn Mower team will have to educate themselves on object oriented programming and

a significant amount of MATLAB to have the devices function as intended.



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After the integration between the lawn mower and the remote control, the kill switch

system would have to be implemented into the remote control and on board the mower itself.

The three kill switches would be the remote control emergency shut off switch, the loss of signal

shut off on the mower, and the accelerometer also on the mower to turn off the motor if the

mower is upside down. This milestone would have a significant amount of programming and

circuitry as well. For the first fail-safe, the remote control would have to have a direct switch to

control the power to the motor from the transmitter. Secondly, the transmitter would have to

monitor the signal from the remote control and, if it became too low, the mower would have to

shut down. Lastly, the accelerometer would require a direct switch to the motor power to shut it

down if the mower orientation was changed drastically.

Lastly, the final milestone would be to have all the systems cooperate smoothly and

produce a functional Robotic Lawn Mower capable of cutting a lawn consistently and with

complete satisfaction. This incorporates adequate lawn height, turning, signal from 25 yards,

and an overall pleasing experience for under a target price. This would also require testing of all

the fail-safes in the system and the ability of changing batteries with ease.



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Part 7 – Conclusions

The Robotic Lawn Mower senior design project aims to be a true testament of the

education obtained upon studying Electrical Engineering at West Virginia University. The

project includes a heavy amount of circuitry, programming, and integration of the two. The

circuitry implements all that we have learned up to Analog Electronics for Electrical

Engineering. The programming section would cover far and beyond the Computer Science class

of Introduction to Object Orientation and the integration of the two areas covers the Computer

Engineering field of microprocessors.

Outside of the classroom, the construction of this device would also be a testament to theteamwork between four students. Sharing the positives and negatives of different aspects of the

project on a daily basis for two semesters is a true test of one’s maturity and willingness to work

in a team environment. This kind of experience is extremely important preparation for what is

waiting on the other side of our degree in industry or academia.

As for the product itself, the final outcome should be a fully functional, handicap and

child accessible, remote controlled lawnmower. This could bring a revolution to the way

lawn mowing is viewed to the average homeowner. No longer would this chore be considered a

hassle, but an enjoyable and safe experience. With the safe, reliable, cheap, and user friendly

remote controlled lawn mower, the Robotic Lawn Mower would be a must have item in every

household.



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Part 8 – Works Cited

[1] - Smith, Sir William. Dictionary of Greek and Roman Antiquities.

[2] - US RE 8560, Passmore, Everett G., "Improvement in Lawn-Mowers", published 23

February 1869, issued 28 January 1879; see pg 1, col 2. For a copy, see Google Patents copy. This

source indicates the patent number as "6,080". According to "British patent numbers 1617 - 1852

(old series)", the patent number would have been assigned sometime after 1852 and taken the form

of "6080/1830".

[3] - The Old Lawnmower Club. "Mower History". The Old Lawnmower Club. Retrieved

2011-04-23.

[4] - Electric lawn mower - http://www.gardenguides.com/131889-history-electric-lawn-

mower.html

[5] - Jonnes, Jill. Empires of Light ISBN 0-375-75884-4. Page 355, referencing O'Neill, John J.,

Prodigal Genius: The Life of Nikola Tesla (New York: David McKay, 1944), p. 167.

[6] - Robolawn mower http://www.brookstone.com/robomow-rl2000-robotic-lawn-

mower?bkeid=compare%7cmercent%7cgooglebaseads%7csearch&mr:trackingCode=4159B119-

B20B-E111-B18D-

001B21A69EB0&mr:referralID=NA&mr:adType=pla&gclid=CNnjoo3SxK4CFUPc4Aodj31RBw

[7] – Amazon.com - Regular electric lawn mower -

http://www.amazon.com/gp/product/B002ZVOLXE/ref=pd_lpo_k2_dp_sr_3?pf_rd_p=486539851&

pf_rd_s=lpo-top-stripe-

1&pf_rd_t=201&pf_rd_i=B00544EFKI&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0KT3CH8DV5CDGM85

VNS8

http://www.brookstone.com/robomow-rl2000-robotic-lawn-mower?bkeid=compare%7cmercent%7cgooglebaseads%7csearch&mr:trackingCode=4159B119-B20B-E111-B18D-001B21A69EB0&mr:referralID=NA&mr:adType=pla&gclid=CNnjoo3SxK4CFUPc4Aodj31RBw










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Zachary Taylor

B A C K G R O U ND R E SE A R C H P A P E R

ROBOTIC LAWN MOWER

Z ACH ARY TAYL OR

2 0 1 2



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CONTENTS

Abstract .................................................................................................................................................................. 154

Problem Statement ............................................................................................................................................ 156

Project Needs................................................................................................................................................... 157

Background history ........................................................................................................................................... 160

Objectives............................................................................................................................................................... 162

Stakeholders ......................................................................................................................................................... 165

Technical Challenges......................................................................................................................................... 167

Conclusion ............................................................................................................................................................. 169

Works Cited........................................................................................................................................................... 170



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ABSTRACT

Many people see mowing the lawn as a burden and do not want to put the effort in

to simply cutting grass when they could be doing something more productive or something

else that is of more importance. Creating a machine that would make cutting grass exciting

and less labor intensive for an individual would appeal to many individuals. This may seem

to be just an act of laziness, but for a busy individual or someone that is incapable of

mowing grass, this creation would be perfect. Say someone has a grass allergy,

immobilized, or otherwise incapable of mowing a lawn by themself; a machine that will

completely cut a yard with little assistance would be something of value to them.

The goal for this project is to create a lawn mower that can be operated with little or

no effort to the individual using it. This can be accomplished in numerous ways, but the

approach being taken is a two-step procedure. The first step will be to create a lawn mower

controlled by the user via remote control. The second step will be to automate the mower

so that a user can program a cutting area and the mower will successfully and precisely cut

the designated area with no assistance.

The first part of the design will look and feel similar to controlling a remote control

car. The design will be user friendly and a fun twist for someone to mow grass. Once the

first part of the design is successfully created flaw free, the addition of components to make

the mower fully autonomous will take place and be tested. The price of this design will

have to be in the range of regular push lawn mowers to be appealing to consumers. This

machine will have to be reliable or there will be no sense for the consumer to have to

monitor the machine constantly and not have any faith in the design. The machine will also

have to be very safe because of the equipment being used (I.E. a spinning mower blade

without direct supervision). This project is not to recreate the lawn mower itself, but adapt

it to the technologies of the 21st century.



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PROBLEM STATEMENT

The problem presented to our group was to create a lawn mower that will mow a

lawn autonomously. The problem given to the group also stated to first create a mower that

was remotely controlled by a user and then take that existing design and adapt it to work

autonomously. The first stage (creating a remotely control mower) is to prepare the setup

for the automation side of this project. By creating a full functionally remote control mower

first, over half of the battle is accomplished because the main controls of maneuvering the

machine are tested and set. Once a reliable remote control mower is created, components

such as sensors, GPS, and computers can then be added and programmed. Once these

components are added and adapted, the mower should then be able to functionautonomously.

Most autonomous lawn mowers already created work in the same fashion as the

robotic vacuum “Roomba”, other than an electric line creates a boundary for the mower

[RoboMow]. The Roomba is a self-contained vacuum cleaner that can vacuum an entire

room without any control or input from a user and senses obstacles to avoid [iRobot]. The

mowers similar to this design operate in much of the same way. The machine creates a

pattern that will encompass the entire area desired to be mowed. As mentioned earlier an

electric wire is needed for most autonomous mowers to create a mowing boundary for the

machine. However, if the electric line is not properly placed, the mower could potentially

cross over the line and travel where it is not supposed to. This type of lawn mower design

involves a great deal of programming, a software heavy design, and in this instance, a

buried guide fence. Our design is going to be more hardware set with software controls

while still maintaining the simplicity and reliability of regular lawn mower. The overall goal

for this mower project is to create an autonomous mower that is very effective and efficientwhile at the same time the machine is safe, simple, and not expensive.



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PROJECT NEEDS

The first thing needed to be addressed with this project is safety. Unlike a robotic

vacuum that simply sucks up dirt and dust, this machine will have a sharp spinning bladethat can cause serious harm. Because of this, safety is of the utmost importance for this

project. The mower will have to include multiple kill switches and sensors that will shut off

the mower when certain situations arise. For instance if the mower overturns or someone

tries to lift the mower while running, the mower will automatically need to stop the blades

from spinning. The mower will also have to be able to be kept within a certain designated

area to mow the desired grass. If the mower somehow proceeds outside of this area, the

mower will need to be shut off and have an alert, or be able to return to the designated

area. There are many safety issues that arise when trying to complete a task of automating

a process. However, in this case there are many unforeseen factors that may occur and

have to be accounted for; such as foreign objects, animals, and other obstacles that could be

lethal to the machine itself.

The next thing that this lawn mower needs to have is a reliable system. If someone

has constantly fix parts and make sure it doesn’t break down or is not performing as it

should, what good is it? The mower will have to have simplistic control system and stableprogramming so that there are no major malfunctions that can occur and halt the process

of cutting grass. The mower also needs to perform the same way each time it is used. Not

meaning that it has to cut the same exact pattern in the grass each time, but cut to the same

extents that it did the previous time and that efficiency is not compromised.

A machine could have an excellent design and perform above all standards, but if the

average consumer cannot afford to purchase the machine, then a great deal of time, effort,

and money has been wasted. The current robotic lawn mowers are in the range of

thousands of dollars which would be equivalent to buying a high grade riding lawn mower

or a cheap used car [Lawnbotts]. For this reason our lawn mower will have to be designed

so that it will be cost efficient so that it can be purchased by an average individual not

looking to spend a fortune on a lawn mower.



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The design of this mower will also have to be made so that an individual can use the

machine with ease. The controls and setup for the mower itself will have to be straight

forward and over complicated. The overall design of the controls for the mower will have

to be simplistic to the user but at the same time be able to encompass all of the needed

information to successfully fulfill to completely mow a designated area.

Since our group has decided to go with the design of using an existing lawn mower

base and modifying it to accomplish the proposed problem statement, the effectiveness of

actually cutting grass should not be lost. The user should still be able to adjust the height of

the mower so that the preference of grass height can be chosen at any point. The mower

should still efficiently cut the grass as it would with human assistance when it is been

retrofitted with remote controls and possibly later when it has been adapted to be fully

autonomous.

And finally, the mower will be more environmentally friendly than the conventional

gas mower. In order to complete this task, the mower being used will have to be an electric

mower. An electric mower does not require a fuel source to be operated, just a battery that

will have to be charged after every use. An electric mower is also quitter than a gas

powered mower, making it easier for other individuals to tolerate when it is in use.



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FIGURE 15: MAIN AND SUBSEQUENT NEEDS FOR PROJECT



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BACKGROUND HISTORY

The act of mowing grass has been around for centuries. Before the early 1800’s

grass was cut primarily using a tool called a scythe that was hand held and required a great

deal of effort to clear a small area of grass. It wasn’t until around 1830 when the first lawn

mower was invented (Patented) which was a simplistic design that consisted of a series of

blades positioned around a cylinder that rotated as the machined was moved [Bellis].

These types of revolutionary designs are a thing of the past when it comes to the

newest technologies for trimming grass. There are mowers that you ride while you cut the

grass, self-propelled mowers that help decrease the strain of pushing a machine, gas or

electric powered mowers, and numerous other designs and shapes. Regardless of how

technologically advanced the machine is or how energy efficient it is, the sole purpose of

these machines are to cut grass so that an area looks appealing and clean to the

individual(s) wanting it trimmed. The creation of newer designs of mowers all have to goal

of making the task of mowing the lawn easier and more efficient for the user. But what

could be easier than having a machine that would cut your grass for you?

The main technology that has influenced this idea of a robot that will mow a lawn

autonomously was the vacuum cleaner “Roomba”. The main selling point about the

“Roomba” is that it could simply place this device in a room and turn it on and it would

begin to vacuum without running into or off any surfaces. These features and main idea are

the same ones that robotic lawn mower makers try to reproduce. However, when the

Roomba was first introduced, society thought that it was too radical of a design and

concept to actually be a working product, but low and behold the Roomba delivered with

stunning results. This is the same path the robotic lawnmower is following as well. There

are many different autonomous mowers on the market today, but there isn’t too much hype

for them yet. The price of these mowers is primarily the case in this situation.

The price of the Roomba was nowhere near the price that it is today, but that was

also due to the cost of that technology during that period of creation. But since the Roomba



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has been around for a while now (Invented in 2002) [iRobot], the robot has still performed

as it was originally designed and the price has reduced to a point where one unit cost about

as much as a regular middle grade vacuum cleaner. Once a manufacturer can successfully

create a robotic mower design that performs as well as an ordinary push mower at a

reasonable price, there will be more of a market for this kind of mower.

There are many different models of robotic lawn mowers like the Roomba inspired

models as well others on the market today. Most of these mowers work off a boundary

system that stakes off a boundary of which the mowers can reach during the process of

cutting grass. Once a mower has reached a defined boundary, the machine rotates itself and

proceeds in another direction until it reaches another boundary. This process is repeated

constantly until every area of the designated region has been covered and the job has been

accomplished. This form of robotic lawn mower is very simplistic and effective. The

boundary design requires a onetime installation of a perimeter fence (usually buried) and

that is it. Once the boundary line is defined, most of the mowers can simply be set to the

area being cut and let loose [RoboMow].

All the robotic lawn mowers currently on the market are still too expensive for the

simple task of cutting grass. The cause for high price of these mowers is mainly due thecomplexities in designs and the extensive amount of time and testing put into the

programming needed to efficiently operate these machines. Also for the mowers that

operate using boundary lines, if the boundary line is not properly set, the mower can still

proceed past the boundary line and cause harm to surroundings past the boundary line and

the mower itself. There are plenty of factors that come into play when an electric machine

is left alone to operate under varying outside conditions that will have to be accounted for

in the creation of this project.



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OBJECTIVES

The expected outcome for this project is for first the creation of a lawn mower that

will cut via remote control and then adapt that design to create a mower to operate

autonomously. The testing of our project will have to occur during summer and beginning

of fall due to weather and growth of grass. There are already robotic lawn mowers in

production, however, they are not readily abundant and are expensive. The hope for this

project is to create a reliable and efficient robotic lawn mower that is not expensive to

create and performs well. The purpose of this project is not to recreate the lawn mower

itself, but to alter it in such a way that minimal effort will be required to perform the task of

mowing grass.

Once a remote controlled lawn mower is soundly created and has minimal errors in

usage, the second stage of the project is to automate the mower so that the user is taken out

of the picture other than setting up the device initially. The second stage is going to take a

great amount of time to accomplish however. Predicting that all designs and creation of this

stage of the project perform as expected, the finished product will help further advance the

mowing industry.

The first outcome of this project will have to be a solid final design that incorporates

all of the features necessary to perform all the tasks posed for this lawn mower to

accomplish. Once a final design has been created to the standards agreed on by the group,

parts for the mower will then have to be obtained. The final design of this lawn mower will

have to have a healthy combination and communication between hardware and software

components. This communication between hardware and software is very vital to the

functionality of this project and can make or break the whole thing if a major error occurs.

The two main aspects of the project needed to be accomplished is the overall safety of the

machine itself and the effectiveness to efficiently and fully cut grass.

Finally, the final design of this mower will have to be cost efficient and within

budget in order to really make an impact on the current robotic models of lawn mowers on



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the market. Since there are multiple versions of robotic lawn mowers currently on the

market, a major outcome to reach would be to create a mower that performs as well or

better than current robotic mowers at a significantly lower price. The successful creation of

this mower may not have a major impact on the mowing industry, but it will be there as

another option for consumers to consider.



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FIGURE 16: OBJECTIVE TREE



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STAKEHOLDERS

One factor that will have to be taken into consideration is the people that this

project will affect. For one thing, the creation of this design may create controversy within

the community of landscapers and other jobs that base business off of mowing grass. If this

mower design becomes popular and people who usually hired workers to mow grass

decide to now cut their own grass, there are going to be many individuals left without jobs.

However for people that would like to have the control of cutting their own grass and are

unable to otherwise, this mower is very appealing to them.

For individuals that currently own and operate their own lawn care service(s), any

mower creation allows for people to cut lawns easier is not a good thing. For the most part,

a new mower design that will cut a yard after some simple configurations or boundary

lines sounds very appealing. But to the people who base their jobs or source of income off

of maintaining yards, this could potentially ruin them. Yes, there is more to yard work than

just mowing the grass (IE weed eating, trimming hedges, mulching, etc…) but if someone

could have a machine cut the grass while they do the other work, there is no need to hire

anyone else to do it for them. So in the perspective of the hardworking landscapers and

lawn maintenance employees, a reliable and affordable robotic lawn mower is a potential

job killer and something they would like to see not succeed.

However, there are plenty of other individuals that would be overzealous to see this

project succeed, other than the project team and their mentor. To begin with, when the

subject of lawn care and mowing grass comes into mind another issue arises, allergies.

There are millions of people in the United States that contain allergies that seriously affect

individuals around grass cutting season [AAFA]. Each year, allergies account for more than

17 million outpatient office visits, primarily in the spring and fall; seasonal allergies

account for more than half of all allergy visits [AAFA]. In some cases, individuals with

severe allergies and are prone to allergic reactions to certain vegetation that may become

airborne when mowing grass are seriously affected during this period. A machine that



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would allow for these individuals to cut their own lawns from a place that allows them to

be protected from the factors that bring on their allergies would bring a world of help.

A robotic lawn mower would allow for any individual to mow their own lawnwithout having to enlist the help of other individuals. For the average person that is

capable of mowing their own lawn and is not affected by allergies, a robotic mower could

still prove to be a useful machine. An individual could simply program the mower to cut

their lawn while they perform the other tasks necessary in lawn care or other jobs that

would need to be accomplished. Even if the individual wants to mow the lawn themselves,

but does not want to exert the physical energy to, they could still use the remote control

capabilities and maintain full control over the mower.

Yes, there are a few individuals that will not benefit from this creation, but it is near

impossible to please every single person in this world. The purpose of this project is to

make the act mowing the yard an easier task than it previously was. The main objective of

the mower is not being altered what so ever, just the way it is gone about. Many individuals

can gain not only an easier way to maintain their lawns, but could now have a more

enjoyable way to do it.



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TECHNICAL CHALLENGES

For our group, there will be many technical challenges when it comes to creating the

autonomous mower but not so much for the first stage. During the first stage of this project,

the mechanical task of take a mower with wheels that do not steer left or right and make

the capable of doing so. Once this has been accomplished, the matter of connecting steering

servos, motor control equipment and a radio receiver to the mower is all that will have to

be accomplished. The exact configuration of how the steering servos will be attached to the

mower will have to be determined still allowing for the mowing height of the mower to

remain intact. The placement, connection between steering servos and propulsion motors,

and power needed for the motor controller is another issue that will have to be tackled forthis project. And finally, the receiver for the remote control transmitter will have to be

placed on the mower and linked to the motor controller and a proper communication

connection will have to be established.

The main designing and testing for this project will come from the second stage of

this project, making the mower operate autonomously. In this stage of the project, there

will be a great amount of programming and testing the equipment based off of created

programs. This brings up the main issue that our group has discovered for our project, no

single individual in the group is extremely proficient at programming. This may cause for

most of the problems that may arise in the creation of the project. However, seeing that

there is a good three months (Summer break) in between the design stage and building

stage of this project, the group has decided to buckle down and learn a programming

language that would be useful. Once the barrier of programming is out of the way, the next

issue at hand will be retrieving information from the sensors and relaying alerts and output

procedures to mower itself.

The issue of how the mower will mow a designated or programmed area will have

to be addressed. As for now, the group has decided to steer in the direction using a GPS to

provide the navigation and boundaries for the mower. This will bring a whole new set of



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technical challenges in that the relation between the area defined on the GPS and the actual

area that the mower will travel will have to be tested. This along with the reliability of the

GPS system overall are going to be two main challenges, not to mention the programming

that will be involved.



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CONCLUSION

There are good amount of factors that will have to be taken into consideration for

this project. The human factor of this project has its pros and cons. The user will have total

control over where the mower cuts, how fast the mower cuts, and ability to maneuver the

mower out of the way of obstacles to avoid damages. The safety issue of this project is a big

concern. Another issue that has will have to be addressed is that there is still a very sharp

blade that is going to be spinning very close to the where the main controls for the mower

are located. Even though current push lawn mowers still have the dangers of the cutting

blade being next to the overall controls, the mower itself is under direct supervision and it

is the responsibility of the user to maintain safety around the mower. Because this mowerwill be operating away from “direct” supervision of the user and the mower will have to be

aware of any object that may come into contact with the mower itself.

This project is going to be very time consuming and require a good amount of

testing. The testing for this project will not only cover hardware elements but also for the

software that is controlling the communication between the controller and the machine

itself. This integration of software and hardware on an already existing mower platform

will be very interesting. The existing parts of the lawn mower themselves will have to be

analyzed for how well the parts will be able to communicate with the parts being added to

the mower. This mower design is nothing near any radical designs of lawn mowers that

have currently been created, but hopefully a similar design can be created a reasonable

price. However if the final product performs as it is designed the outcome will be very

rewarding and add yet another twist on the act of mowing grass.



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WORKS CITED

1. Bellis, Mary. "Greener Pastures." About.com. n. page. Web.

<http://inventors.about.com/library/inventors/bllawns.htm>.

2. "FAQs." iRobot . N.p., n.d. Web.

<http://store.irobot.com/shop/index.jsp?categoryId=4331597&ab=CMS_IR

BT_iRobot101_GetToKnow_062110

3. "Lawnbotts Easy Bundles." Lawnbotts. N.p., 04 Feb 2012. Web.

<http://www.lawnbotts.com/LawnBott_Bundles.html>.

4. "How does it work?." RoboMow . N.p., n.d. Web. <http://www.robomow.com/en-

USA/faqs-usa/how-does-it-work>.

5. "Allergy Facts and Figures." AAFA. N.p., n.d. Web.

<http://www.aafa.org/display.cfm?id=9&sub=30



Appendix 4: Summary of Changes from Original

Invisible FenceWhile there were several options for a boundary system for the original design, the final product was

chosen to have the invisible fence. The invisible fence system is one that diversifies this robotic lawnmower from any other project. Using the magnetic field of a wire entrenched into the ground, a

receiver has been integrated into our obstacle interrupt system to warn the mower of crossing outside

of a bounded area. Essentially the same technology as an electric dog collar, the electrical pulse that is

normally sent to a canine does to the laptop perched onto the mower. This system was chosen for its

user friendliness and minimal amount of needed maintenance.

Battery orientationWhile the original design was planned to have two 12-volt batteries in series to power the robotic lawn

mower, the electric lawn mower that was purchased for the purpose of this project had one 24-volt

battery. This proved to be sufficient to power the rest of the project going forward.

Roll-over AccelerometerAnother necessary safety feature that was originally planned was the accelerometer. This device would

be used to sensor when the lawn mower would be flipped in a position where the blade would be facing

upwards in a highly dangerous manner This accelerometer would sense the orientation of the mower

final report lawn bot

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