CHAPTER 1

1. INTRODUCTION

It is a industrial cum medical purpose robot with natural power source like solar energy.

Tongue Drive system (TDS) is a tongue-operated unobtrusive wireless assistive technology,

which can potentially provide people with severe disabilities with effective computer access

and environment control. It translates users’ intentions into control commands by detecting and

classifying their voluntary tongue motion utilizing a small permanent magnet, secured on the

tongue,and an array of magnetic sensors mounted on a headset outside the mouth or an

orthodontic braceinside.The main aim of this project is to design and construct a tongue

controlled robot and device switching wirelessly using RF technology. This device is portable

and this system operation is entirely driven by wireless technology. The user can control the

Robot directions with the simple tongue movement and he can also request the basic needs like

water, food or medicine using voice module.

The control system consists of Hall Effect sensor and microcontroller. Microcontroller

collects data from the sensor and transmits the encoded data through the RF transmitter. At

receiver end RF receiver receives the data through the decoder and fed as input to the micro

controller. The controller performs the corresponding actions i.e., Robot movement.

This Project consists of two Microcontroller Units, Robot, relay, Triac, Hall Effect sensor and

wireless communication through RF technology. Robot is made up of High torque Geared DC

Motors, the Motors Directions can be changed through the set of instructions given from the

Hall Effect sensor and the action of these Instructions is already loaded into the Microcontroller

using Embedded C programming. The RF receiver provides the information to the

microcontroller (on board computer) from RF transmitter and the controller judges whether the

instruction is right movement or left movement based on the tongue movement and controls the

direction. This device is portable and this system operation is entirely driven by wireless

technology.This project makes use of a Relay and Triac for switching the devices and APR-

9600 voicechip for audio announcements, DC motors for Robot movement, wireless camera to

view the 8 surroundings, TV for viewing live images and Micro controller, which is

programmed, with the help of embedded C instructions. This microcontroller is capable of

1

communicating with transmitter and receiver modules. The Hall Effect sensor detects the

movement of the tongue and provides the information to the microcontroller (on board

computer) and the controller judges whether the instruction is right movement or left

movement instruction and controls the operation respectively. To perform the task, the

controller is loaded with intelligent program written using Embedded ‘C’ language.

Robotics is the branch of technology that deals with the design, construction, operation, and

application of robots as well as computer systems for their control, sensory feedback, and

information processing. These technologies deal with automated machines that can take the

place of humans in dangerous environments or manufacturing processes, or resemble humans

in appearance, behavior, and/or cognition. Many of today's robots are inspired by nature

contributing to the field of bio-inspired robotics.

Sensors allow robots to receive information about a certain measurement of the environment, or

internal components. This is essential for robots to perform their tasks, and act upon any

changes in the environment to calculate the appropriate response. They are used for various

forms of measurements, to give the robots warnings about safety or malfunctions, and to

provide real time information of the task it is performing.

1.1. Overview

1.1.1 Tongue Controller

An embedded system is a combination of software and hardware to perform a dedicated task.

Some of the main devices used in embedded products are Microprocessors and

Microcontrollers. Microprocessors are commonly referred to as general purpose processors as

they simply accept the inputs, process it and give the output. In contrast, a microcontroller not

only accepts the data as inputs but also manipulates it, interfaces the data with various devices,

controls the data and thus finally gives the result.

The Tongue Controlled speaking robot using 16F877A Microcontroller is an exclusive project

that can move the wheel chair according to the instructions given by the above said

microcontroller.

2

Tongue Drive system (TDS) is a tongue-operated unobtrusive assistive technology, which can

potentially provide people with severe disabilities with effective computer access and

environment control. It translates users’ intentions into control commands by detecting and

classifying their voluntary tongue motion utilizing a small permanent magnet, ecured on the

tongue, and an array of magnetic sensors mounted on a headset outside the mouth or an

orthodontic brace inside. We have developed customized interface circuitry and implemented

four control strategies to drive a powered wheel chair (PWC) using an external TDS prototype.

The magnetic sensors are nothing but hall-effect sensors. A Hall Effect sensor is a transducer

that varies its output voltage in response to changes in magnetic field. In its simplest form, the

sensor operates as an analogue transducer, directly returning a voltage. With a known magnetic

field, its distance from the Hall plate can be determined. The control system consists of Hall

Effect sensor and microcontroller. Microcontroller collects data from the sensor and

Microcontroller makes to move the motors of the wheel chair in appropriate direction. The

direction is decided by the microcontroller depending on the magnet present at different Hall

Effect sensors. The microcontroller is loaded with intelligent program written using embedded

‘C’ language.

Fig:1.1 Block Diagram Of Tongue Controller.

3

Tongue Drive system (TDS) is a tongue-operated unobtrusive wireless assistive technology,

which can potentially provide people with severe disabilities with effective computer access

and environment control. It translates users' intentions into control commands by detecting and

classifying their voluntary tongue motion utilizing a small permanent magnet, secured on the

tongue, and an array of magnetic sensors mounted on a headset outside the mouth or an

orthodontic brace inside. We have developed customized interface circuitry and implemented

four control strategies to drive a powered wheelchair (PWC) using an external TDS prototype.

The system has been evaluated by five able-bodied human subjects. The results showed that all

subjects could easily operate the PWC using their tongue movements, and different control

strategies worked better depending on the users' familiarity with the TDS.

1.1.2. Obstacle Detector

In robotics, obstacle avoidance is the task of satisfying some control objective subject to non-

intersection or non-collision position constraints. In unmanned air vehicles, it is a hot topic.

What is critical about obstacle avoidance concept in this area is the growing need of usage of

unmanned aerial vehicles in urban areas for especially military applications where it can be

very useful in city wars. Normally obstacle avoidance is considered to be distinct from path

planning in that one is usually implemented as a reactive control law while the other involves

the pre-computation of an obstacle-free path which a controller will then guide a robot along.

We have designed a simple robot which detects obstacles and correspondingly changes its

direction to avoid collisions. We have used the mbed controller and interfaced it with an LCD

display and 3 Infra-Red sensors. The LCD display indicates the distance of the robot from the

obstacle when the robot is in the range of 80 cm to 10 cm and it also displays the direction in

which the robot will turn when it sees an obstacle. The 3 infra-red sensors are used to detect

obstacles in the front, right and left direction. The front sensor is the primary sensor which

keeps checking if there are any obstacles in its path in the front direction. Simultaneously the

right and left sensors also keep checking for obstacles in the right and left direction

respectively. Whenever there is any obstacle detected in the range of 10 centimeters by the

front sensor, the robot will stop and take a turn in either the right or left direction depending on

which side is clear and free from obstacles. If both the right and left side are free from

4

obstacles, we have made the robot turn right (One could make it turn left by choice). When the

front sensor and left sensor both detect obstacles within the range of 10 centimeters, the robot is

made to turn right. Similar logic is used to make the robot left turn. If all the 3 sensors detect

obstacles within the range of 10 centimeters, the robot moves in the reverse direction.

Fig.1.2 Obstacle Detector

The main aim of this project is to design a robot that can follow a black path without collisions

detect the end of the path and turn back. The black path below the car can be determined using

the principle that black color absorbs all radiations and the presence of an obstacle is detected

using ultrasonic waves.

5

1.1.2.1. Infrared Transmitter and Receiver

IR transmitter consists of a IR led while the receiver used is IR transistors L14G2. When the

Infrared rays fall over base of the IR Led, it is turned on. To catch this variation, the collector

of IR transistor is fed to a comparators in LM324 IC as shown in the circuit diagram. We use 4

such Tx Rx modules each at the corner of a rectangle. When the robot reaches the end of the

path, only the forward Tx Rx detect white path while the backward Tx Rx module still detect

the black path. This case is used to turn around the robot until the forward Tx Rx modules

detect black path. In other cases, the robot turns left if one/both of the right Tx Rx module

detect a white path. Similarly, the robot turns right if one/both of the left Tx Rx module detect

white path. If all of the Tx Rx module detect a black path the robot moves forward.

Fig.1.3 IR Circuit

6

Infrared (IR) light is electromagnetic radiation with longer wavelengths than those of visible

light extending from the nominal red edge of the visible spectrum at 700 nanometers (nm) to

1 mm. This range of wavelengths corresponds to a frequency range of approximately

430 THz down to 300 GHz. Most of the thermal radiation emitted by objects near room

temperature is infrared.

Infrared radiation was discovered in 1800 by astronomer William Herschel, who discovered a

type of invisible radiation in the light spectrum beyond red light, by means of its effect upon a

thermometer. Slightly more than half of the total energy from the Sun was eventually found to

arrive on Earth in the form of infrared. The balance between absorbed and emitted infrared

radiation has a critical effect on Earth's climate.

Infrared light is emitted or absorbed by molecules when they change their rotational-

vibration movements. Infrared energy elicits vibrationl modes in a molecule through a change

in the dipole moment, making it a useful frequency range for study of these energy states for

molecules of the proper symmetry. Infrared spectroscopy examines absorption and

transmission of photons in the infrared energy range.

Infrared light is used in industrial, scientific, and medical applications. Night-vision devices

using active near-infrared illumination allow people or animals to be observed without the

observer being detected. Infrared astronomy uses sensor-equipped telescopes to penetrate dusty

regions of space, such as molecular clouds; detect objects such as planets, and to view

highly red-shifted objects from the early days of the universe. Infrared thermal-imaging

cameras are used to detect heat loss in insulated systems, to observe changing blood flow in the

skin, and to detect overheating of electrical apparatus.

Thermal-infrared imaging is used extensively for military and civilian purposes. Military

applications include target acquisition, surveillance, night vision, homing and tracking. Humans

at normal body temperature radiate chiefly at wavelengths around 10 μm (micrometers). Non-

military uses include thermal efficiency analysis, environmental monitoring, industrial facility

inspections, remote temperature sensing, short-ranged wireless communication, spectroscopy,

and weather forecasting.

7

Infrared is used in night vision equipment when there is insufficient visible light to see. Night

vision devices operate through a process involving the conversion of ambient light photons into

electrons that are then amplified by a chemical and electrical process and then converted back

into visible light. Infrared light sources can be used to augment the available ambient light for

conversion by night vision devices, increasing in-the-dark visibility without actually using a

visible light source.

The use of infrared light and night vision devices should not be confused with thermal imaging,

which creates images based on differences in surface temperature by detecting infrared

radiation that emanates from objects and their surrounding environment.

1.1.2.2. Ultrasonic Transmitter and Receiver

Ultrasonic signals are used to detect obstacles in the path of the robot. Ultrasonic signals scores

over Infrared signals in that they can detect obstacles of irregular shape as well as that of black

colUltrasonic sensors (also known as transceivers when they both send and receive, but more

generally called transducers) work on a principle similar to radar or sonar which evaluate

attributes of a target by interpreting the echoes from radio or sound waves respectively.

Ultrasonic sensors generate high frequency sound waves and evaluate the echo which is

received back by the sensor. Sensors calculate the time interval between sending the signal and

receiving the echo to determine the distance to an object.

This technology can be used for measuring wind speed and direction (anemometer), tank or

channel level, and speed through air or water. For measuring speed or direction a device uses

multiple detectors and calculates the speed from the relative distances to particulates in the air

or water. To measure tank or channel level, the sensor measures the distance to the surface of

the fluid. Further applications include: humidifiers, sonar, medical ultrasonography, burglar

alarms and non-destructive testing.

Systems typically use a transducer which generates sound waves in the ultrasonic range, above

18,000 hertz, by turning electrical energy into sound, then upon receiving the echo turn the

sound waves into electrical energy which can be measured and displayed.

The technology is limited by the shapes of surfaces and the density or consistency of the

material. Foam, in particular, can distort surface level readings.

8

1.2 Microcontroller

The microcontroller used here is 89c51. It is interfaced with DC motor driver H-Bridge IC

L293D. The pins P0.0 to P0.3 receive the 4 IR signals indicating weather they are on black or

white path. The microcontroller is programmed to drive the robot in either forward, left or right

direction. The microcontroller also continuously monitors the pin P0.4 which is connected to

the output of ultrasonic obstacle detection circuit. When the pin P0.4 detects a obstacle, the

microcontroller stops the robot. On reaching the end of the path, the microntroller rotates the

robot until it encounters the black path and then continues foward.

Fig.1.4 Normal motor Driving Block Diagram

9

1.3 RF TRANSMITTER AND RECEIVER MODULE

These modules are now widely and cheaply available with the operating frequency of 433 MHz

The transmitter module accepts serial data. The encoder IC takes in parallel data at the TX side

packages it into serial format and then transmits it with the help of a RF transmitter module. At

the RX end, the decoder IC receives the signal via the RF receiver module, decodes the serial

data and reproduces the original data in the parallel format.

1.3.1 THE TX433 (Transmission Module)

The TX433 wireless RF transmitter uses on/off keying to transmit data to the matching

receiver, RX433. The data input “keys” the saw resonator in the transmitter when the input is

+3 volts or greater, AM modulating the data onto the 433 MHz carrier. The data is then

demodulated by the receiver, which accurately reproduces the original data. The data input is

CMOS level Compatible when the unit is run on +5 volts.

When driving with a CMOS input, there must be enough level to achieve at least 3V on the

data input, 5V is preferable. This is due to the start-up time of the oscillator needing to be fast

to accurately reproduce your data. If the voltage is too low, the oscillator will not start fast

enough to accurately reproduces your data, especially at higher data rates. Luckily not much

drive is needed, so this should be easy since it is 22K ohms of load. Almost any CMOS output

will drive this without any problems. There are some CMOS outputs which have very little

drive capability which may not work, so testing the voltage at the data input may be a wise

choice if you are having problems.

The simplest antenna consists of a piece of wire approximately 6 to 7 inches long. If you desire

more range you can try a ground plane antenna or a Yagi such as the Ramsey 400-4 model. The

antenna should be tuned for the 433 MHz band for best operation.

Having two Yagi antennas, one for the transmitter and one for the receiver will allow you to

extend the range considerably, but since they are directional, this would be best for if your

receiver and transmitter are in fixed positions.

10

Fig 1.5. 433 MHz Transmitter

1.3.1.1 TRANSMITTER CIRCUIT CODIND

#include<reg52.h>

sbit en=P3^5;

sbit rs=P3^7;

sbit rw=P3^6;

void delay(int a)

{int i,j;

for(i=0;i<=a;i++)

for(j=0;j<=127;j++);

}

void cmd(int a)

11

{

en=1;

rw=0;

rs=0;

P1=a;

delay(1);

en=0;

}

void dat(int a)

{

en=1;

rw=0;

rs=1;

P1=a;

delay(1);

en=0;

}

void lcddata(char* arr)

{ int i;

for(i=0;arr[i]!='\0';i++)

{dat(arr[i]);

12

}

}

void main()

{int i;

cmd(0x38);

cmd(0x0C);

for(i=0;i<10;i++)

{

cmd(0x80);

dat('0'+i);

cmd(0xC0);

dat('0'+i);

delay(100);

}

while(1);

}

1.3.2 The RX433 (Receiver Module)

The receiver shown in Figure also contains just one transistor. It is biased to act as a

regenerative oscillator, in which the received antenna signal causes the transistor to switch to

high amplification, thereby automatically arranging the signal detection. Next, the ‘raw’

demodulated signal is amplified and shaped-up by op-amps. The result is a fairly clean digital

13

signal at the output of the receiver. The logic high level is at about 2/3 of the supply voltage,

i.e., between 3 V and 4.5 V.

The range of the simple system shown in Figures is much smaller than that of more expensive

units, mainly because of the low transmit power (approx. 1 mW) and the relative insensitivity

and wide-band nature of the receiver. Moreover, amplitude-modulated noise is not suppressed

in any way.

The simplest antenna consists of a piece of wire approximately 6 to 7 inches long. If you desire

more range you can try a ground plane antenna or a Yagi such as the Ramsey 400-4 model. The

antenna should be tuned for the 433 MHz band for best operation.

Having two Yagi antennas, one for the transmitter and one for the receiver will allow you to

extend the range considerably, but since they are directional, this would be best for if your

receiver and transmitter are in fixed positions.

Fig 1.6 433 MHz RF Receiver

14

1.3.2.1 RECEIVER CIRCUIT CODING

#include<reg52.h>

sbit en=P3^5;

sbit rs=P3^7;

sbit rw=P3^6;

void delay(int a)

{int i,j;

for(i=0;i<=a;i++)

for(j=0;j<=127;j++);

}

void cmd(int a)

{

en=1;

rw=0;

rs=0;

P1=a;

delay(1);

en=0;

}

15

void dat(int a)

{

en=1;

rw=0;

rs=1;

P1=a;

delay(1);

en=0;

}

void lcddata(char* arr)

{ int i;

for(i=0;arr[i]!='\0';i++)

{dat(arr[i]);

}

}

void main()

{int i;

cmd(0x38);

cmd(0x0C);

for(i=0;i<10;i++)

{

16

cmd(0x80);

dat('0'+i);

cmd(0xC0);

dat('0'+i);

delay(100);

}

while(1);

}

1.4 H-Bridge and DC motors

The robot is driven by DC motors. To drive the motors we use an H-bridge-L293d which

boosts the microcontroller logic voltage to 9v that is required to drive these motors. In our case,

we used a 9v, 100rpm DC motor. To achieve higher speeds, DC motors of higher torque and

voltage can be used.

1.3.3 TSOP

Thin Small Outline Package or TSOP is a type of surface mount IC package. They are very

low-profile (about 1mm) and have tight lead spacing (as low as 0.5mm).

They are frequently used for RAM or Flash memory ICs due to their high pin count and small

volume. In some applications, they are being supplanted by ball grid array packages which can

achieve even higher densities. The prime application for this technology is memory. SRAM,

Flash memory, FSRAM and E2PROM find this package symbiotic with end-use products. It

answers the needs required by telecom, cellular, memory modules, PC Cards (PCMCIA cards),

wireless, net books and countless other product applications.TSOP is the smallest leaded form

factor for flash memory.

17

The TSOP4P.. series are miniaturized receivers for Mid range proximity sensor systems. A PIN

diode and a preamplifier are assembled on a lead frame, the epoxy package acts as an IR filter.

The output pulse width of the TSOP4P.. has an almost linear relationship to the distance of the

emitter or the distance of an reflecting object. The TSOP4P.. is optimized to suppress almost all

spurious pulses from energy saving fluorescent lamps. This component has not been qualified

according to automotive specifications.

Fig: 1.7 TSOP

1.3.4 MAGNETIC SENSOR

A Hall effect sensor is a transducer that varies its output voltage in response to a magnetic field.

Hall effect sensors are used for proximity switching, positioning, speed detection, and current

sensing applications.In its simplest form, the sensor operates as an analog transducer, directly

returning a voltage. With a known magnetic field, its distance from the Hall plate can be

determined. Using groups of sensors, the relative position of the magnet can be deduced.

Electricity carried through a conductor will produce a magnetic field that varies with current,

and a Hall sensor can be used to measure the current without interrupting the circuit. Typically,

the sensor is integrated with a wound core or permanent magnet that surrounds the conductor to

be measured.Frequently, a Hall sensor is combined with circuitry that allows the device to act

in a digital (on/off) mode, and may be called a switch in this configuration. Commonly seen in

industrial applications such as the pictured pneumatic cylinder, they are also used in consumer

18

equipment; for example some computer printers use them to detect missing paper and open

covers. When high reliability is required, they are used in keyboards.

Hall sensors are commonly used to time the speed of wheels and shafts, such as for internal

combustion engine ignition timing, tachometers and anti-lock braking systems. They are used

in brushless DC electric motors to detect the position of the permanent magnet. In the pictured

wheel with two equally spaced magnets, the voltage from the sensor will peak twice for each

revolution. This arrangement is commonly used to regulate the speed of disk drives.

Fig:1.8 Magnetic Sensor

CHAPTER 2

19

OVERVIEW

2.1 Project Overview

It is the industrial cum medical purpose robot with help of natural power source with solar

energy. In this project we want to implement multitask via our robot. This robot work as a

obstacle detector, tongue controller etc. A proper mean by multitasking is multifeature we can

run at a time via our multitasking robot. It is totally based on microcontroller configuration.

Main concept of our project is we apply a natural power source.

Robotics is the branch of technology that deals with the design, construction, operation, and

application of robots as well as computer systems for their control, sensory feedback, and

information processing. These technologies deal with automated machines that can take the

place of humans in dangerous environments or manufacturing processes, or resemble humans

in appearance, behavior, and/or cognition. Many of today's robots are inspired by nature

contributing to the field of bio-inspired robotics.

Tongue Drive system (TDS) is a tongue-operated unobtrusive wireless assistive technology,

which can potentially provide people with severe disabilities with effective computer access

and environment control. It translates users' intentions into control commands by detecting and

classifying their voluntary tongue motion utilizing a small permanent magnet, secured on the

tongue, and an array of magnetic sensors mounted on a headset outside the mouth or an

orthodontic brace inside. We have developed customized interface circuitry and implemented

four control strategies to drive a powered wheelchair (PWC) using an external TDS prototype.

The system has been evaluated by five able-bodied human subjects. The results showed that all

subjects could easily operate the PWC using their tongue movements, and different control

strategies worked better depending on the users' familiarity with the TDS.

20

2.2 Robotics

2.2.1 Introduction to Robotics

In practical usage, a Robot is a mechanical device which performs automated physical tasks,

either according to direct human supervision, a pre-defined program, or a set of general

guidelines using artificial intelligence techniques. Robots are typically used to do the tasks that

are too dirty, dangerous, difficult, repetitive or dull for humans. This usually takes the form of

industrial robots used in manufacturing lines. Other applications include toxic waste cleanup,

underwater and space exploration, mining, search and rescue, and mine finding. Recently

however, robots are finding their way into the consumer market with uses in entertainment,

vacuum cleaning, and lawn mowing. A robot may include a feedback-driven connection

between sense and action, not under direct human control, although it may have a human

override function. The action may take the form of electro-magnetic motors or actuators (also

called effectors) that move an arm, open and close grips, or propel the robot. The step by step

control and feedback is provided by a computer program run on either an external or embedded

computer or a microcontroller. By this definition, a robot may include nearly all automated

devices.

Ask a number of people to describe a robot and most of them will answer they look like a

human.  Interestingly a robot that looks like a human is probably the most difficult robot to

make.  It is usually a waste of time and not the most sensible thing to model a robot after a

human being.  A robot needs to be above all functional and designed with qualities that suit its

primary tasks.  It depends on the task at hand whether the robot is big, small, is able to move or

nailed to the ground.  Each and every task means different qualities, form and function; a robot

needs to be designed with the task in mind.

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2.2.1.2 Mobile Robots

Mars Explorer image

  Mobile robots are able to move, usually they perform task

such as search areas. A prime example is the Mars Explorer,

specifically designed to roam the mars surface.

Mobile robots are a great help to such collapsed building for

survivors Mobile robots are used for task where people cannot

go.  Either because it is too dangerous of because people

cannot reach the area that needs to be searched.  

 

    Mobile robots can be divided in two categories:  

 Rolling Robots:  Rolling robots have wheels to move around. 

These are the type of robots that can quickly and easily search

move around.  However they are only useful in flat areas,

rocky terrains give them a hard time.  Flat terrains are their

territory.  

   

   Walking Robots:  Robots on legs are usually brought in

when the terrain is rocky and difficult to enter with wheels. 

Robots have a hard time shifting balance and keep them from

tumbling.  That’s why most robots with have at least 4 of them,

usually they have 6 legs or more.  Even when they lift one or

more legs they still keep their balance.  Development of legged

robots is often modeled after insects or crawfish..  

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Stationary Robots

Robots are not only used to explore areas or imitate a human

being.  Most robots perform repeating tasks without ever

moving an inch.  Most robots are ‘working’ in industry

settings.  Especially dull and repeating tasks are suitable for

robots.  A robot never grows tired, it will perform its duty day

and night without ever complaining.  In case the tasks at hand

are done, the robots will be reprogrammed to perform other

tasks..  

Autonomous Robots

   Autonomous robots are self supporting or in other words self

contained.  In a way they rely on their own ‘brains’.

  Autonomous robots run a program that give them the

opportunity to decide on the action to perform depending on

their surroundings.  At times these robots even learn new

behavior.  They start out with a short routine and adapt this

routine to be more successful at the task they perform.  The

most successful routine will be repeated as such their behavior

is shaped.  Autonomous robots can learn to walk or avoid

obstacles they find in their way.  Think about a six legged

robot, at first the legs move ad random, after a little while the

robot adjust its program and performs a pattern which enables

it to move in a direction.  

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Remote-control Robots

   An autonomous robot is despite its autonomous not a very

clever or intelligent unit.  The memory and brain capacity is

usually limited. An autonomous robot can be compared to an

insect in that respect.

  In case a robot needs to perform more complicated yet

undetermined tasks an autonomous robot is not the right choice.

Complicated tasks are still best performed by human beings

with real brainpower.  A person can guide a robot by remote

control.  A person can perform difficult and usually dangerous

tasks without being at the spot where the tasks are performed. 

To detonate a bomb it is safer to send the robot to the danger

area.  

Dante 2, a

NASA robot

designed to

explore

volcanoes via

remote control.

2.2.2 Virtual Robots

 Virtual robots don’t exits in real life.  Virtual robots are just programs, building blocks of

software inside a computer.  A virtual robot can simulate a real robot or just perform a

repeating task.  A special kind of robot is a robot that searches the world wide web.  The

internet has countless robots crawling from site to site. These WebCrawler’s collect

information on websites and send this information to the search engines. Another popular

virtual robot is the chatterbot.  These robots simulate conversations with users of the internet. 

One of the first chatterbots was ELIZA.  There are many varieties of chatterbots now, including

E.L.V.I.S.

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BEAM Robots

111    BEAM is short for Biology, Electronics, Aesthetics and

Mechanics.  BEAM robots are made by hobbyists. BEAM

robots can be simple and very suitable for starters.

 

Biology

Robots are often modeled after nature.  A lot of BEAM robots look remarkably like insects. 

Insects are easy to build in mechanical form.  Not just the mechanics are in inspiration also the

limited behavior can easily be programmed in a limited amount of memory and processing

power.

Two basic ways of using effectors are to move the robot around (locomotion) or to move other

objects around (manipulation). This distinction divides robotics into two mostly separate

categories: mobile robotics (moving) and manipulator robotics (grabbing).

Joints connect parts of manipulators. The most common joint types are:

1. rotary (rotation around a fixed axis)

2. prismatic (linear movement)

A parallel robot is one whose arms (primary axes) have three concurrent prismatic joints or

both prismatic and rotary joints. Degrees of freedom (DOF) means axes of movement. The

human arm has seven Degrees of Freedom. A "6 DOF" arm is highly flexible.

25

Proprioceptive sensors sense the robot's actuators (e.g., shaft encoders, joint angle sensors).

Proprioception is one of the most important senses of the human body.

Alternately, robot has been used as the general term for a mechanical man, or an automaton

resembling an animal, either real or imaginary. It has come to be applied to many machines

which directly replace a human or animal in work or play. In this way, a robot can be seen as a

form of biomimicry. Lack of anthropomorphism is perhaps what makes us reluctant to refer to

the highly complex modern washer-dryer as a robot. However, in modern understanding, the

term implies a degree of autonomy that would exclude many automatic machine tools from

being called robots. It is the search for ever more highly autonomous robots which is the major

focus of robotics research and which drives much work in artificial intelligence.

The term robot is also often used to refer to sophisticated mechanical devices that are remotely

controlled by human beings, such as waldoes and ROVs, even though these devices are not

autonomou.

26

2.3 INFRARED EMITTER DETECTOR

The infrared emitter detector pair act as an eye with a flashlight in the infrared spectrum. The

detector (a transistor) detects all ambient infrared light. The emitter (a LED) emits infrared

light into an otherwise dark (in the infrared spectrum) room.

Requirements

Low, typical LED power requirements.

Tips and Uses

1. Don’t bother using this circuit outside, the sun will flood your IR detector and make it

useless.

2. Certain indoor lighting can also emit IR interference

3. Only if you modulate the IR emitter and set the detector to only detect modulated IR

can you use this outside. This is commonly done with Sharp IR rangefinders.

4. Tweaking is necessary to determine sensitivity of your circuit. Sensitivity will help

increase range but also increase ambient interference.

5. By using certain resistor values, your IR emitter detector can also detect color, such as

for line tracking.

27

2.3.1 Sonar

Basic Description

Detects obstacles and can determine object softness/hardness through echolocation.

Typical sonar require ground, power, signal transmit, and signal recieve lines. Transmit

a short square wave and the sonar emits a mostly inaudible sound. The sonar keeps the

signal recieve line low before the emission and after detecting the return of the

emission, high. The distance can be determined by measuring in time how long the

recieve line is kept high. FYI, the speed of sound at sea level is 340.29 m/s.

Availability and Cost

Available online for around $20-$30.

Power Requirements

Low, but depends on how active sonar are set to.

Tips and Uses

1. Using multiple sonar can be a challenge in that they can trigger each other

inadvertently.

2. If using multiple sonar, you must trigger each independently and wait for a return.

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3. This can take a long time if you have 10+ sonar on your robot, so you will have to

fiddle with combinations of sonar running simultaneously

4. Sonar does not work at very short distances (several inches)

5. Remember, sound bounces off of walls and can interfere with later emission readin

29

2.3.2 DIGITAL COMPASS

Basic Description

The digital compass gives measurements based on Earth's magnetic field for robot navigation.

Inside this commonly available MEMS are tiny nano-structures that bend due to

electromagnetic fields. When this MEMS experiences any form of EM field, the tiny structures

bend by an amount which can be electrically detected. Cheaper digital compasses usually have

a resolution of around +/- 5 degrees, but newer and better ones can detect with a better

accuracy.

Availability and Cost

It is easily available for $30-$100. It is best to buy them with supporting circuitry included to

avoid any interference from bad electrical design.

Power Requirements

Minimal, typical logic only.

Tips and Uses

Keep digital compasses far away from anything that emits EM, such as motors, transformers,

inductors, etc.

Large conductive items significantly altar magnetic fields (cars, fridges, steel plates, etc.)

Use this device to help for navigation, such as robot race tracks or navigating a maze

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2.3.3 SENSORS - ACCELEROMETER

Basic Description

It detects motion, vibration, and angle with respect to gravity.

Inside this commonly available MEMS are tiny nano-structures that bend due to momentum

and gravity. When this MEMS experiences any form of acceleration (gravity is a downward

acceleration) the tiny structures bend by an amount which can be electrically detected. This

means accelerometers can be used to detect and/or control for vibration of a device,

acceleration of a robot actuator, or even the angle of the accelerometer with respect to gravity

(useful for biped robots).

Note that an accelerometer works on only a single axis, so if you wish to detect on X, Y, and Z

planes you need 3 of them. Today many accelerometer MEMS's come with multiple axis for

simplicity.

Availability and Cost

They are easily available and very affordable. Usually require support circuitry. Dimension

Engineering has a great plug and play dual axis accelerometer which requires no additional

support circuitry.

Power Requirements

Minimal, typical logic only.

Tips and Uses

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1. Placing an accelerometer on a mobile robot that experiences bumps can trigger the

accelerometer unintentionally.

2. Use a large capacitor to smooth out output over several hundred milliseconds (testing

required) to prevent this.

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2.3.4 TACTILE BUMP SENSOR CIRCUIT

Tactile Bump Sensors are great for collision detection, but the circuit itself also works

fine for user buttons and switches as well.

There are many designs possible for bump switches, often depending on the design and

goals of the robot itself. But the circuit remains the same. They usually implement a

mechanical button to short the circuit, pulling the signal line high or low. An example is

the microswitch with a lever attached to increase its range, as shown above.

There are several versions below, depending on how you plan to use the circuit and

your available switches. For the resistor use a very high value, such as 40kohms.

Tactile Bump Sensor Circuits

Voltage

goes high

with contact

Voltage

goes low

with contact

More efficient switch for 3 lead switches

(use for microswitches)

Tactile switches only work if your robot can stop instantaneously (like when moving slowly).

There is no point ramming the wall, then the switch saying 'oops, wall here.

33

2.4 Types of Motors

DC Motors

From the start, DC motors seem quite simple. Apply a voltage to both terminals, and it spins.

But what if you want to control which direction the motor spins? Correct, you reverse the

wires. Now what if you want the motor to spin at half that speed? You would use less voltage.

But how would you get a robot to do those things autonomously? How would you know what

voltage a motor should get? Why not 50V instead of 12V? What about motor overheating?

Operating motors can be much more complicated than you think.

DC motors are non-polarized - meaning that you can reverse voltage without any bad things

happening. Typical DC motors are rated from about 6V-12V. The larger ones are often 24V or

more. But for the purposes of a robot, you probably will stay in the 6V-12V range. So why do

motors operate at different voltages? As we all know (or should), voltage is directly related to

motor torque. More voltage, higher the torque. But don't go running your motor at 100V

because that’s just not nice. A DC motor is rated at the voltage it is most efficient at

running. If you apply too few volts, it just wont work. If you apply too much, it will overheat

and the coils will melt. So the general rule is, try to apply as close to the rated voltage of the

motor as you can. Also, although a 24V motor might be stronger, do you really want your robot

to carry a 24V battery (which is heavier and bigger) around? So a standard recommendation is

do not surpass 12V motors unless you really need the torque.

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Stepper Motors

Stepper Motors work under a very similar principle to DC motors, except they have many

coils instead of just one. So to operate a stepper motor, one must activate these different coils in

particular patterns to generate motor rotation. So stepper motors need to be sent patterned

commands to rotate. These commands are sent as high and low logic over several lines, and

must be pulsed in a particular order and combination. Steppers are often used because each

'step,' separated by a set step angle, can be counted and used for feedback control. For

example, a 10 degree step angle stepper motor would require 36 commands to rotate 360

degrees. However external torque can force movement to a different step, invalidating

feedback. Therefore external torque must never exceed the holding torque of a stepper.

The Robologic stepper motor is a four phase unipolar motor with a step angle of 7.5 degrees. It

has 6 wires coming from it in 2 sets of 3. Each set is connected to its own winding. The central

pin is the ground pin, and the 2 pins to the left (pin 1) and right (pin 2) are connected to each

35

winding. The arrangement is the same on the second set of pins.

Fig:2.1 magnetic sensor circuitary

The Robocore can control up to 2 stepper motors using its standard dc motor connections. To

follow this example attaches pin 1 and 2 to the Robocore's first motor output and pins 3 and 4

to the second motor output. The two ground pins can be connected together and attached to the

batteries negative terminal.

The following sequence steps the motor through one complete cycle.

Step Pin1 Pin2 Pin3 Pin4

1 ON OFF ON OFF

2 ON OFF OFF ON

3 OFF ON OFF ON

4 OFF ON ON OFF

1 ON OFF ON OFF

The motor can be made to rotate anticlockwise by stepping backwards through the sequence.

I.E. Step 4, 3, 2,1,4,3 etc

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Notes on Stepper Motors

1. Stepper motors can be easily found in any 3.5" disk drive

2. Require special stepper motor controllers

3. Have a set resolution, higher resolutions mean higher accuracy but lower holding torque

4. If torque applied to stepper is greater than holding torque, stepper will lose accurate

position measurements

Voltage

1. Polarized (current cannot be reversed)

2. Typically from 5-12V, but can range to extremes in special application motors

3. Higher voltages generally mean more torque, but also require more power

4. Steppers can run above or below rated voltage (to meet other design requirements)

5. Most efficient at rated voltage

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2.4.2 Servo Motors

Servos are DC motors with built in gearing and feedback control loop circuitry. And no motor

drivers required!

Servos are extremely popular with robot, RC plane, and RC boat builders. Most servo motors

can rotate about 90 to 180 degrees. Some rotate through a full 360 degrees or more. However,

servos are unable to continually rotate, meaning they can't be used for driving wheels (unless

modified), but their precision positioning makes them ideal for robot legs and arms, rack and

pinion steering, and sensor scanners to name a few. Since servos are fully self contained, the

velocity and angle control loops are very easy to implement, while prices remain very

affordable. To use a servo, simply connect the black wire to ground, the red to a 4.8-6V source,

and the yellow/white wire to a signal generator (such as from your microcontroller). Vary the

square wave pulse width from 1-2ms and your servo is now position/velocity controlled.

Servos can operate under a range of voltages. Typical operation is from 4.8V to 6V. There are a

few micro sized servos that can operate at less, and now a few Hi-tech servos that operate at

much more. The reason for this standard range is because most microcontrollers and RC

receivers operate near this voltage. So what voltage should you operate at? Well, unless you

have a battery voltage/current/power limitation, you should operate at 6V. This is simply

because DC motors have higher torque at higher voltages.

While the black and red wires provide power to the motor, the signal wire is what you use to

command the servo. The general concept is to simply send an ordinary logic square wave to

your servo at a specific wave length, and your servo goes to a particular angle (or velocity if

your servo is modified). The wavelength directly maps to servo angle.

So how do you apply this square wave to your servo? If your robot is remote controlled, your

RC receiver will apply the proper square wave for you. If however your robot is running from a

microcontroller, you must:

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So how many milliseconds do you keep the port high? It all depends on the servo. You may

have to tweak for each individual servo some several microseconds’ difference. The standard

time vs angle is represented in this chart:

Fig:2.2 Waveform of servo motor

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2.5 ROBOT BATTERIES

The robots are no longer limited to bulky low power non-rechargeable batteries, and today

there is a large assortment to suit your robots' demands. How are batteries rated? With any

battery you will see a voltage and a power rating. Battery voltages can be somewhat

complicated. When fully recharged, a battery will often be 15% above its voltage rating. When

fully discharged, about 15% below its rating. A fully charged battery will also immediately

drop below its rating when driving heavy loads, such as a DC motor. To increase battery

voltage, wire multiple of them in series. Batteries also cannot supply an infinite current. So

expect batteries of different types but equal voltages to have different current outputs. To

increase battery current output, wire multiple of them in parallel. This is why batteries often

come in assembled packs of smaller cells. So when using a battery, make sure your circuit

handles changes in battery voltage. For the power rating you will see something like 1200mAh.

mAh means milliamps per hour. So if it is 1200mAh, that means the battery can supply 1.2

amps for one hour or 2.4 amps for 30 minutes or 0.6 amps for two hours.

Alkaline batteries are the most common, easiest to

get, and cheapest too. However they are useless, dont

buy them. They have low power capacities, are

heavy, have trouble supplying large amounts of

current in short time periods, and get expensive to

constantly replace. The same goes for Zinc-carbon

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batteries, which suck even more.

Lead Acid batteries were developed in the

late 1800s, and were the first commercially

practical batteries. They remain popular

because they are easy and inexpensive to

manufacture. Rechargeable lead-acid

batteries have been available since the 1950s

and have become the most widely used type

of battery today.

Their drawback is remember that lead acid

batteries have the serious problem of being

very large and heavy, need to always be kept

charged, and do not have the high discharge

rates as the more modern batteries.

There are three main types of lead acid batteries. Wet Cell (flooded) Gel Cell, and Absorbed

Glass Mat (AGM). The Gel Cell and the AGM batteries are specialty batteries that typically

cost twice as much as a premium wet cell. However they store very well and do not tend to

sulfate or degrade as easily or as easily as wet cell.

Lithium (Li-ion) is the new standard for portable

power. Li-ion batteries have the same high energy

capacity as NiMHs, power output rates of NiCads,

and weigh about 20%-35% less. They also have

zero memory effect problems, meaning you can

recharge whenever. Although lithium batteries are

the most advanced for portable power, they are

also the most expensive. Also, they are made out

of totally non-toxic material, making them safe for

cute squirrels and pretty trees. What is to be

41

remembered is to, lithium ignites very easily, and

forms large quantities of hydrogen when put in

contact with water, so don't shoot at it or blow it

up or anything of that nature. Also, fire

extinguishers are usually water based, so don’t use

them on lithium battery fires.

42

Interesting points about Robotics

Building robots involves the development of a wide range of skills, including creative thinking,

design, mechanics, electronics and programming - all of which are highly valued in industry.

Our interest in the subject could lead us into an exciting and fulfilling career at the cutting edge

of technology!

Before the 1960s, robot usually meant a manlike mechanical device (mechanical man or

humanoid) capable of performing human tasks or behaving in a human manner. Today robots

43

come in all shapes and sizes, including small robots made of LEGO, and larger wheeled robots

that play robot football with a full-size ball.

What many robots have in common is that they perform tasks that are too dull, dirty, delicate or

dangerous for people. Usually, we also expect them to be autonomous, that is, to work using

their own sensors and intelligence, without the constant need for a human to control them.

Looked at this way, a radio controlled aero plane is not a robot, nor are the radio controlled

combat robots that appear on television. However, there is no clear dividing line between fully

autonomous robots and human-controlled machines. For example, the robots that perform

space missions on planets like Mars may get instructions from humans on Earth, but since it

can take about ten minutes for messages to get back and forth, the robot has to be autonomous

during that time.

Where did the word robot originate?

The word robot was introduced in 1920 in a play by Karel Capek called R.U.R. or Rossum's

Universal Robots. Robot comes from the Czech word robota, meaning forced labour or

drudgery. In the play, human-like mechanical creatures produced in Rossum's factory are docile

slaves. Since they are just machines, the robots are badly treated by humans. One day a

misguided scientist gives them emotions, and the robots revolt, kill nearly all humans and take

over the world. However, because they are unable to reproduce themselves, the robots are

doomed to die.

What are the Laws of Robotics?

The term robotics was coined in the 1940s by science fiction writer Isaac Asimov. In a series of

stories and novels, he imagined a world in which mechanical beings were mankind's devoted

helpmates. They were constrained to obey what have become known as Asimov's Laws of

Robotics:

1. A robot may not injure a human being, or, through inaction, allow a human being to

come to harm.

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2. A robot must obey the orders given it by human beings except where such orders would

conflict with the First Law.

3. A robot must protect its own existence as long as such protection does not conflict with

the First or Second Law.

What was the first practical robot?

A prototype industrial robot arm named Unimate (designed by George Devol and Joseph

Engelberger) was sold to General Motors in 1959. It plucked hot automobile parts out of a die-

casting machine and quenched them in water.

The 1960s and 1970s saw a revolution in manufacturing as robots replaced humans for many

repetitive jobs. However, these robots were not intelligent by today’s standards. Usually they

were programmed by humans training their movements, and they had very little decision-

making capabilities. There are still many robots like this in factories today, but the trend is

towards more intelligent general-purpose robots that can do more than just paint a panel or

screw in a bolt.

What can't robots do?

It is very difficult to give a robot the ability to perform a wide variety of tasks, move around in

cluttered surroundings, recognize objects in the ‘real world’, understand normal speech, and

think for itself. These are exciting areas of current research in robotics and artificial

intelligence.

For example, the robot shown here has the problem of

deciding where to cross the river. How can it make this

decision? How would you do it? Perhaps you have come

across a similar situation before. Perhaps you could look

it up in a guide book. Perhaps you would reason that B is

better than C because the water is likely to be shallower?

Perhaps you would choose A, because you tried it before.

All these ways of making decisions come very naturally

45

to humans, but they are very difficult to program into

robots.

Another great problem in robotics is getting them to understand language. This is very

important in problem-solving. For example, the four cards below have a letter on one side and a

number on the other. If a card has a vowel (a, e, i, o, u) on one side then it has an even number

on the other. Which cards do you have to turn over to see if this is true? Think about your

answer, and then point to a card to turn it over.

Now consider the following cards where the rule is ‘every time I go to Paris I go by plane’.

Which cards have to be turned over to test this? Again, think about your answer before turning

the card over.

The answer to the first question is that you have to turn over the E to see if it has an even

number on the back and you have to turn over the 7 to check that it does not have a vowel on

the back. In an experiment, only 12% of people got this second part right (did you?).

The answer to the second question is much easier. Of course you have to turn over the Paris

card to check that it has the word plane on the back, but now it’s much more obvious that you

have to turn over the train card to make sure it does not have Paris on the back. In the

experiment mentioned above, 60% of people got the second part right.

46

These problems are logically the same, so the experimenters drew the conclusion that the

meaning of the symbols is an important part of problem solving. Since robots have very poor

language capabilities, their ability to use this kind of reasoning is very limited.

Another of the great problems in robotics is getting them to ‘see’. Although it is easy to put a

camera on a robot, it is much more difficult to get the robot to understand what is in an image.

Most humans have miraculously good vision. We are able to resolve great ambiguity in scenes.

It has proved much more difficult to get robots to understand what is in their universe, and

machine vision remains one of the big unsolved problems in robotics research.

There are other problems in robotics that make progress slow. For example, your body is

covered with skin, and this contains millions of sensors that allow you to do many fantastically

precise things. For example, try typing at a computer with gloves on. The lack of touch

feedback will make it very difficult. Also your muscles enable you to have very fine control.

Even if you are rather clumsy, you are probably much better at manipulating objects than the

average robot. Most people would not let a robot dust their favorite china.

Will robots ever be as good as humans?

Many futurists believe that robots will eventually and inevitably become more capable than

humans, but some experts in artificial intelligence assert that machines will never be able to

develop the consciousness and emotions needed for reasoning and creativity.

Nonetheless, there are already commercially available robots that can live in our houses and do

basic chores for us. Robots are very good at processing certain kinds of information, and they

are ideally suited to answering the telephone and being controlled over the Internet.

The International RoboCup Federation has set itself the challenge of having a team of

humanoid robot football players beat the human world champions by 2050. Can you image

that? It means that robots will have to become as nimble and skilful as Beckham. It will require

the invention of many new materials – for example, a human soccer player could be badly hurt

if it clashed with a robot made of metal. It will also require an enormous improvement in

47

machine vision. If you play sports such as football, tennis, or even snooker, next time you play

think about the huge amount of information that comes through your eyes.

Will robots take over from humans?

This is a popular science fiction theme, and the answer depends on whether robots will ever

attain consciousness and emotions. In stories like 2001: A Space Odyssey and Terminator,

humans always find a way to outwit intelligent machines that try to take over control. That's

fiction, however, and fact is often stranger than fiction!

The suggestion that robots will take over because they might become more intelligent than

humans overlooks one critical fact: the people who have power in human societies are usually

not the most intelligent in the obvious, intellectual way. They have different kinds of ‘human

intelligence’, including the ability to understand other people, and to influence their behavior.

The sensible answer to the question as to whether robots will take over is that they probably

won’t in the near future. There are many reasons for this. The first is that the robots of today

have puny brains compared to humans, and they do not have the ability to organise in the same

way as humans. Our societies are very complex and allow us to achieve many very advanced

things. It is unlikely that robots could overtake us in the near future. Even so, it is something

that we should keep an eye on, since all scientists have a responsibility not to do things that

damage society.

However, for the most part, robots play a very positive role in our societies, and we can expect

them to be used in many ways that make life better for us all.

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CHAPTER 3

CIRCUIT DESCRIPTION

3.1 INTRODUCTION OF MAIN COMPONENT

i. Microcontroller

ii. Dc Motors

iii. Motor Driving IC

iv. Interfacing IC

v. Voltage Regulator IC

vi. Resistors

vii. Capacitors

3.1.1. 8051 Microcontroller AT89C51

AT89C51 is an 8-bit microcontroller and belongs to Atmel's 8051 family. ATMEL 89C51 has

4KB of Flash programmable and erasable read only memory (PEROM) and 128 bytes of RAM.

It can be erased and program to a maximum of 1000 times.

In 40 pin AT89C51, there are four ports designated as P1, P2, P3 and P0. All these ports are 8-bit

bi-directional ports, i.e., they can be used as both input and output ports. Except P0 which needs

external pull-ups, rest of the ports have internal pull-ups. When 1s are written to these port

pins, they are pulled high by the internal pull-ups and can be used as inputs. These ports are

also bit addressable and so their bits can also be accessed individually.

Fig.3.1 AT89C51 MICROCONTROLLER 

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Port P0 and P2 are also used to provide low byte and high byte addresses, respectively, when

connected to an external memory. Port 3 has multiplexed pins for special functions like serial

communication, hardware interrupts, timer inputs and read/write operation from external

memory. AT89C51 has an inbuilt UART for serial communication. It can be programmed to

operate at different baud rates. Including two timers & hardware interrupts, it has a total of six

interrupts. 

Fig. 3.2 Pin Diagram of AT89C51

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3.1.2 DC MOTORS

A brushed DC motor is an internally commutated electric motor designed to be run from a

direct current power source. Brushed motors were the first commercially important application

of electric power to driving mechanical loads, and DC distribution systems were used for more

than 100 years to operate motors in commercial and industrial buildings. Brushed DC motors

can be varied in speed by changing the operating voltage or the strength of the magnetic field.

Depending on the connections of the field to the power supply, the speed and torque

characteristics of a brushed motor can be altered to provide steady speed or speed inversely

proportional to the mechanical load. Brushed motors continue to be used for electrical

propulsion, cranes, paper machines and steel rolling mills. Since the brushes wear down and

require replacement, brushless motors using power electronic devices have displaced brushed

motors from many applications.

Fig.3.3 DC Motor (150 rpm)

3.1.3. Motor Driving IC L293D

L293D is a typical Motor driver or Motor Driver IC which allows DC motor to drive on either

direction. L293D is a 16-pin IC which can control a set of two DC motors simultaneously in

any direction. It means that you can control two DC motor with a single L293D IC.

51

The l293d can drive small and quiet big motors as well, check the Voltage Specification at the

end of this page for more info. It can be found in any electronic shop very easily and it costs

around 80 Rupees (INR) or around 1.3 $ Dollar. You can find the necessary pin diagram,

working, a circuit diagram, Logic description and Project as you read through.

Fig.3.4 L293D Motor Driving IC

It works on the concept of H-bridge. H-bridge is a circuit which allows the voltage to be flown

in either direction. As you know voltage need to change its direction for being able to rotate the

motor in clockwise or anticlockwise direction, Hence H-bridge IC are ideal for driving a DC

motor.

In a single l293d chip there two h-Bridge circuit inside the IC which can rotate two dc motor

independently. Due its size it is very much used in robotic application for controlling DC

motors. Given below is the pin diagram of a L293D motor controller.

There are two Enable pins on l293d. Pin 1 and pin 9, for being able to drive the motor, the pin 1

and 9 need to be high. For driving the motor with left H-bridge you need to enable pin 1 to

high. And for right H-Bridge you need to make the pin 9 to high. If anyone of the either pin1 or

pin9 goes low then the motor in the corresponding section will suspend working. It’s like a

switch.

The there 4 input pins for this l293d, pin 2,7 on the left and pin 15 ,10 on the right as shown on

the pin diagram. Left input pins will regulate the rotation of motor connected across left side

52

and right input for motor on the right hand side. The motors are rotated on the basis of the

inputs provided across the input pins as LOGIC 0 or LOGIC 1.

Fig.3.5 Circuit Diagram For l293d motor driver IC controller

3.1.3.1. Voltage Specification

VCC is the voltage that it needs for its own internal operation 5v; l293D will not use this

voltage for driving the motor. For driving the motor it has a separate provision to provide motor

supply VSS (V supply).  L293d will use this to drive the motor. It means if you want to operate

a motor at 9V then you need to provide a Supply of 9V across VSS Motor supply.

53

The maximum voltage for VSS motor supply is 36V. It can supply a max current of 600mA per

channel. Since it can drive motors Up to 36v hence you can drive pretty big motors with this

l293d.

VCC pin 16 is the voltage for its own internal Operation. The maximum voltage ranges from

5v and up to 36v.

Fig.3.6 Pin Diagram of L293D IC

3.1.3.2. L293D Logic Table

Lets consider a Motor connected on left side output pins (pin 3,6). For rotating the motor in

clockwise direction the input pins has to be provided with Logic 1 and Logic 0.   

54

Pin 2 = Logic 1 and Pin 7 = Logic 0 | Clockwise Direction

Pin 2 = Logic 0 and Pin 7 = Logic 1 | Anticlockwise Direction

Pin 2 = Logic 0 and Pin 7 = Logic 0 | Idle [No rotation] [Hi-Impedance state]

Pin 2 = Logic 1 and Pin 7 = Logic 1 | Idle [No rotation]

In a very similar way the motor can also operated across input pin 15,10 for motor on the right

hand side.

3.1.4. Interfacing IC MAX 232

The MAX232 is an IC, first created in 1987 by Maxim Integrated Products, that converts

signals from an RS-232 serial port to signals suitable for use in TTL compatible digital logic

circuits. The MAX232 is a dual driver/receiver and typically converts the RX, TX, CTS and

RTS signals.

The drivers provide RS-232 voltage level outputs (approx. ± 7.5 V) from a single + 5 V supply

via on-chip charge pumps and external capacitors. This makes it useful for implementing RS-

232 in devices that otherwise do not need any voltages outside the 0 V to + 5 V range, as power

supply design does not need to be made more complicated just for driving the RS-232 in this

case.

The receivers reduce RS-232 inputs (which may be as high as ± 25 V), to standard 5 V TTL

levels. These receivers have a typical threshold of 1.3 V, and a typical hysteresis of 0.5 V.

Fig.3.7. MAX 232 Interfacing IC

55

The later MAX232A is backwards compatible with the original MAX232 but may operate at

higher baud rates and can use smaller external capacitors — 0.1 μF in place of the 1.0 μF

capacitors used with the original device.

The newer MAX3232 is also backwards compatible, but operates at a broader voltage range,

from 3 to 5.5 V.

The MAX232 (A) has two receivers (converts from RS-232 to TTL voltage levels), and two

drivers (converts from TTL logic to RS-232 voltage levels). This means only two of the RS-

232 signals can be converted in each direction. Typically, a pair of a driver/receiver of the

MAX232 is used for TX and RX signals, and the second one for CTS and RTS signals.

There are not enough drivers/receivers in the MAX232 to also connect the DTR, DSR, and

DCD signals. Usually these signals can be omitted when e.g. communicating with a PC's serial

interface. If the DTE really requires these signals, either a second MAX232 is needed, or some

other IC from the MAX232 family can be used. Also, it is possible to directly wire DTR (DB9

pin 4) to DSR (DB9 pin 6) without going through any circuitry. This gives automatic (brain

dead) DSR acknowledgment of an incoming DTR signal.

Fig.3.8 Pin Diagram of MAX 232 Interfacing IC

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3.1.5 Voltage Regulator IC 7805

7805 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed linear

voltage regulator ICs. The voltage source in a circuit may have fluctuations and would not give

the fixed voltage output. The voltage regulator IC maintains the output voltage at a constant

value. The xx in 78xx indicates the fixed output voltage it is designed to provide. 7805 provides

+5V regulated power supply. Capacitors of suitable values can be connected at input and output

pins depending upon the respective voltage levels.

Fig.3.9 7805 Voltage Regulator IC

Voltage regulator IC's are the IC’s that are used to regulate voltage.IC 7805 is a 5V Voltage

Regulator that restricts the voltage output to 5V and draws 5V regulated power supply.

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It comes with provision to add heat sink. The maximum value for input to the voltage regulator

is 35V. It can provide a constant steady voltage flow of 5V for higher voltage input till the

threshold limit of 35V. If the voltage is near to 7.5V then it does not produce any heat and

hence no need for heat sink. If the voltage input is more, then excess electricity is liberated as

heat from 7805.

It regulates a steady output of 5V if the input voltage is in rage of 7.2V to 35V. Hence to avoid

power loss try to maintain the input to 7.2V. In some circuitry voltage fluctuation is fatal (for

e.g. Microcontroller), for such situation to ensure constant voltage IC 7805 Voltage Regulator

is used. For more information on specifications of 7805 Voltage Regulator please refer the data

sheet here (IC 7805 Voltage Regulator Data Sheet).

IC 7805 is a series of 78XX voltage regulators. It’s a standard, from the name the last two

digits 05 denotes the amount of voltage that it regulates. Hence a 7805 would regulate 5v and

7806 would regulate 6V and so on.

The schematic given below shows how to use a 7805 IC, there are 3 pins in IC 7805, pin 1

takes the input voltage and pin 3 produces the output voltage. The GND of both input and out

are given to pin 2.

Fig.3.10 Pin Diagram of 7805 Voltage Regulator IC

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Voltage Regulator is one of the most important and commonly used electrical components.

Voltage Regulators are responsible for maintaining a steady voltage across an Electronic

system. Voltage fluctuations may result in undesirable effect on an electronic system, so to

maintaining a steady constant voltage is necessary according to the voltage requirement of a

system.

Let us assume a condition when a simple light emitting diode can take a max of 3V to the max,

what happens if the voltage input exceeds 3V ?, of course the diode will burn out. This is also

common with all electronic components like, led’s, capacitors, diodes etc. The slightest

increase in voltage may result in the failure of entire system by damaging the other components

too. For avoiding Damage in such situations voltage regulator are used for regulated power

supply.

Fig.3.11 7805 VOLTAGE REGULATOR IC CIRCUIT

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3.1.6 CRYSTAL OSCILLATOR

A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a

vibrating crystal of piezoelectric material to create an electrical signal with a very precise

frequency. This frequency is commonly used to keep track of time (as in quartz wristwatches),

to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for

radio transmitters and receivers. The most common type of piezoelectric resonator used is the

quartz crystal, so oscillator circuits incorporating them became known as crystal oscillators, but

other piezoelectric materials including polycrystalline ceramics are used in similar

circuits.Quartz crystals are manufactured for frequencies from a few tens of kilohertz to

hundreds of megahertz. More than two billion crystals are manufactured annually. Most are

used for consumer devices such as wristwatches, clocks, radios, computers, and cell phones.

Quartz crystals are also found inside test and measurement equipment, such as counters, signal

generators, and oscilloscopes.

In crystal oscillators, the usual electrical resonant circuit is replaced by a mechanically vi-

brating crystal. The crystal (usually quartz) has a high degree of stability in holding constant at

whatever frequency the crystal is originally cut to operate. The crystal oscillators are, therefore,

used whenever great stability is needed, for example, in communication transmitters, and

receivers, digital clocks etc.

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A quartz crystal exhibits a very important property known as piezo-electric effect. When a

mechanical pressure is applied across the faces of the crystal, a voltage proportional to the

applied mechanical pressure appears across the crystal. Conversely, when a voltage is applied

across the crystal surfaces, the crystal is distorted by an amount proportional to the applied

voltage. An alternating voltage applied to a crystal causes it to vibrate at its natural frequency.

Besides quartz, the other substances that exhibit the piezo-electric effect are Rochelle salt and

tourmaline. Rochelle salt exhibits the greatest piezoelectric effect, but its applications are

limited to manufacture of microphones, headsets and loudspeakers. It is because the Rochelle

salt is mechanically the weakest and strongly affected by moisture and heat. Tourmaline is

most rugged but shows the least piezo-electric effect. Quartz is a compromise between the

piezoelectric effect of Rochelle salt and the mechanical strength of tourmaline. It is inexpensive

and readily available in nature. It is mainly the quartz crystal that is used in radio-frequency

(RF) oscillators.

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CHAPTER 4

4.1. Introduction of Layout and PCB Designing

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PCB(Printed Circuit Board) is a device which connects all the electronic components in

single substrate. PCB design is a software technique to draw and simulate the working of

the PCB keeping all the electrical components required for our board.

A printed circuit board (PCB) mechanically supports and electrically connects electronic

components using conductive tracks, pads and other features etched from copper sheets

laminated onto a non-conductive substrate. PCB's can be single sided (one copper layer),

double sided (two copper layers) or multi-layer. Conductor on different layers is connected

with plated-through holes called vias. Advanced PCB's may contain components - capacitors,

resistors or active devices - embedded in the substrate.

Printed circuit boards are used in all but the simplest electronic products. Alternatives to PCBs

include wire wrap and point-to-point construction. PCBs are more costly to design but allow

automated manufacturing and assembly. Products are then faster and cheaper to manufacture,

and potentially more reliable.

When the board has only copper connections and no embedded components it is more correctly

called a printed wiring board (PWB) or etched wiring board. Although more accurate, the term

printed wiring board has fallen into disuse. A PCB populated with electronic components is

called a printed circuit assembly (PCA), printed circuit board assembly or PCB assembly

(PCBA). The IPC preferred term for assembled boards is circuit card assembly (CCA), for

assembled backplanes it is backplane assemblies. The term PCB is used informally both for

bare and assembled boards.

4.2 DESIGN

Printed circuit board artwork generation was initially a fully manual process done on clear

Mylar sheets at a scale of usually 2 or 4 times the desired size. The schematic diagram was first

converted into a layout of components pin pads, then traces were routed to provide the required

interconnections. Pre-printed non-reproducing mylar grids assisted in layout, and rub-on dry

transfers of common arrangements of circuit elements (pads, contact fingers, integrated circuit

profiles, and so on) helped standardize the layout. Traces between devices were made with self-

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adhesive tape. The finished layout "artwork" was then photographically reproduced on the

resist layers of the blank coated copper-clad boards.

Fig.5.1 PCB Layout

4.3 Manufacturing Process

Subtractive methods remove copper from an entirely copper-coated board:

1. Silk screen printing uses etch-resistant inks to protect the copper foil. Subsequent

etching removes the unwanted copper. Alternatively, the ink may be conductive, printed

on a blank (non-conductive) board. The latter technique is also used in the manufacture

of hybrid circuits.

2. Photoengraving uses a photomask and developer to selectively remove a photoresist

coating. The remaining photoresist protects the copper foil. Subsequent etching removes

the unwanted copper.

3. PCB milling uses a two or three-axis mechanical milling system to mill away the

copper foil from the substrate. A PCB milling machine (referred to as a 'PCB

Prototyper') operates in a similar way to a plotter, receiving commands from the host

software that control the position of the milling head in the x, y, and (if relevant) z axis.

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Data to drive the Prototyper is extracted from files generated in PCB design software

and stored in HPGL or Gerber file format.

4.4 Chemical Etching

Chemical etching is usually done with ammonium per sulfate or ferric chloride. For PTH

(plated-through holes), additional steps of electro less deposition are done after the holes are

drilled, then copper is electroplated to build up the thickness, the boards are screened, and

plated with tin/lead. The tin/lead becomes the resist leaving the bare copper to be etched away.

The simplest method, used for small-scale production and often by hobbyists, is immersion

etching, in which the board is submerged in etching solution such as ferric chloride. Compared

with methods used for mass production, the etching time is long. Heat and agitation can be

applied to the bath to speed the etching rate. In bubble etching, air is passed through the etchant

bath to agitate the solution and speed up etching. Splash etching uses a motor-driven paddle to

splash boards with etchant; the process has become commercially obsolete since it is not as fast

as spray etching. In spray etching, the etchant solution is distributed over the boards by nozzles,

and recirculated by pumps. Adjustment of the nozzle pattern, flow rate, temperature, and

etchant composition gives predictable control of etching rates and high production rates.

As more copper is consumed from the boards, the etchant becomes saturated and less effective;

different etchants have different capacities for copper, with some as high as 150 grams of

copper per litre of solution. In commercial use, etchants can be regenerated to restore their

activity, and the dissolved copper recovered and sold. Small-scale etching requires attention to

disposal of used etchant, which is corrosive and toxic due to its metal content.

The etchant removes copper on all surfaces exposed by the resist. "Undercut" occurs when

etchant attacks the thin edge of copper under the resist; this can reduce conductor widths and

cause open-circuits. Careful control of etch time is required to prevent undercut. Where

metallic plating is used as a resist, it can "overhang" which can cause short-circuits between

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adjacent traces when closely spaced. Overhang can be removed by wire-brushing the board

after etching.

4.5 Transmitter Layout

Fig.4.2 Layout Of Transmitter

4.6 Receiver Layout

Fig.4.3 Layout Of Receiver

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4.7 Line Follower Layout

Line-following robots with pick-and-placement capabilities are commonly used in

manufacturing plants. These move on a specified path to pick the components from specified

locations and place them on desired locations.

Basically, a line-following robot is a self-operating robot that detects and follows a line drawn

on the floor. The path to be taken is indicated by a white line on a black surface. The control

system used must sense the line and manoeuvre the robot to stay on course while constantly

correcting the wrong moves using feedback mechanism, thus forming a simple yet effective

closed-loop system.

Fig.4.4 Simulation Circuitry Of Industrial Cum Medical Purpose Robot.

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The source program for the project is written in Assembly language and assembled using Metalink’s ASM51 assembler, which is freely available on the Internet for download. It is well commented for easy understanding and works as per the flow-chart. The hex file ‘robot.hex’ is to be burnt into the microcontroller.

Fig.4.5 Flow Chart Of Robot.

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CHAPTER 5

FUTURE SCOPE

5.1. Future Scope and Applications

Robotics is the art and commerce of robots, their design, manufacture, application, and

practical use. Robots will soon be everywhere, in our home and at work. They will change the

way we live. This will raise many philosophical, social, and political questions that will have to

be answered. In science fiction, robots become so intelligent that they decide to take over the

world because humans are deemed inferior. In real life, however, they might not choose to do

that. Robots might follow rules such as Asimov’s Three Laws of Robotics, that will prevent

them from doing so. When the Singularity happens, robots will be indistinguishable from

human beings and some people may become Cyborgs: half man and half machine. Table of

Contents [show] 1 Social Impact 1.1 Minimal requirements 2 Types of Robots 3 Applications 4

Home Applications 5 Medical Applications 6 Military applications 7 Technical challenges 8

Timeline 9 Robotics in 2020 10 See also 11 Links 12 References edit Social Impact Given that

in the next two decades robots will be capable of replacing humans in most manufacturing and

service jobs, economic development will be primarily determined by the advancement of

robotics. Given Japan's current strength in this field, it may well become the economic leader in

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the next 20 years (part 1, part 2). Marshall Brain also discusses the emergence of robotic

economy.

i. Caterpillar plans to develop remote controlled machines and expects to develop fully

autonomous heavy robots by 2021. Some cranes already are remote controlled.

ii. It was demonstrated that a robot can perform a herding task.

iii. Robots are increasingly used in manufacturing (since 1960s). In the auto industry they

can amount for more than half of the "labor". There are even "lights off" factories such

as an IBM keyboard manufacturing factory in Texas that is 100% automated.

iv. Robots such as HOSPI  are used as couriers in hospitals, etc. Other hospital tasks

performed by robots are receptionists, guides and porters helpers, (not to

mention surgical robot helpers such as Da Vinci)

v. Robots can serve as waiters and cooks.

5.1.1. Future Development

5.1.1.1 Technological trends

Various techniques have emerged to develop the science of robotics and robots. One method

is evolutionary robotics, in which a number of differing robots are submitted to tests. Those

which perform best are used as a model to create a subsequent "generation" of robots. Another

method is developmental robotics, which tracks changes and development within a single robot

in the areas of problem-solving and other functions.

5.1.1.2 Technological development

Japan hopes to have full-scale commercialization of service robots by 2025. Much

technological research in Japan is led by Japanese government agencies, particularly the Trade

Ministry.

As robots become more advanced, eventually there may be a standard computer operating

system designed mainly for robots. Robot Operating System is an open-source set of programs

being developed at Stanford University, the Massachusetts Institute of Technology and

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the Technical University of Munich, Germany, among others. ROS provides ways to program a

robot's navigation and limbs regardless of the specific hardware involved. It also provides high-

level commands for items like image recognition and even opening doors. When ROS boots up

on a robot's computer, it would obtain data on attributes such as the length and movement of

robots' limbs. It would relay this data to higher-level algorithms. Microsoft is also developing a

"Windows for robots" system with its Robotics Developer Studio, which has been available

since 2007.

5.1.1.3 New functions and abilities

The Caterpillar Company is making a dump truck which can drive itself without any human

operator.

Many future applications of robotics seem obvious to people, even though they are well beyond

the capabilities of robots available at the time of the prediction. As early as 1982 people were

confident that someday robots would: 1. clean parts by removing molding flash 2. spray paint

automobiles with absolutely no human presence 3. pack things in boxes—for example, orient

and nest chocolate candies in candy boxes 4. make electrical cable harness 5. Load trucks with

boxes—a packing problem 6. handle soft goods, such as garments and shoes 7. shear sheep

8. prosthesis 9. cook fast food and work in other service industries 10. household robot.

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CHAPTER 6

APPLICATION

6.1 Advantages

i. The use of robotics is widely spread in the 21st century. There is not a single sector that

doesn't use robotic systems in carrying out technical processes. Robotic systems have

come a long way since their invention, and are getting more and more advanced. They

can perform flawless work in very less time. They have many advantages that

contribute to various factors such as time,quality,safety,etc.

ii. Robotic systems have the capability of impressively meliorating the quality of work.

They don't make any mistakes and errors as humans do. This saves a lot of important

output and production time. They provide optimum output in regards to quality as well

as quantity. In the medical field, they are used to carry out complicated surgeries which

are very difficult for doctors and surgeons to perform. In the industrial sector they

prevent any errors in the production of goods.

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iii. If robots are used for production purposes, the throughput speed rises, which directly

has an effect on production. They have the capability to work at a constant speed

without the need to take short breaks, sleeps, vacations, and some other time-spending

factors. Moreover, they have the potential to produce considerably more than a human

worker.

iv. The use of robotic systems in the industrial sector is a necessity nowadays, as more and

more products are to be manufactured in a very less time, and that too with high-quality

and accuracy. Big industrial manufacturing giants have robotic systems that work 24/7.

Such systems can even do the work of approximately 100 or more human workers at a

time.

v. Car and electronic manufacturing companies mostly make use of such automated

systems. They employ robotic systems in several testing and assembling procedures

which would be difficult and time-consuming for human workers to carry out. Robotic

arms are a simple example of such technologies. They also may be utilized for robotic

painting and robotic welding jobs. Robotic packaging machinery is used in companies

which manufacture daily-use products.

vi. Robotic systems have also proven to play a very important role in the medicinal and

surgical sector, be it in manufacturing medicines and drugs or carrying out simple tasks

in specific surgeries. However, robots don't perform the whole procedure in surgeries,

but certainly assist the surgeons to perform the task accurately. A surgeon may use a

'robotics surgery coordinator' to perform a surgery without making big incisions, and

also in lesser time than normal. The use of robotics in nursing is increasing due to the

shortage of efficient manpower. Moreover, a robot may be used in performing an

unmanned operation which is known as a robotic surgery.

vii. Nowadays, robots that can perform house duties are also being manufactured. However,

the technology of house robots is not being used commercially. Some examples include

robotic pool cleaners and robotic vacuum cleaners. Robotics programming is a way of

feeding information into the robots regarding what tasks are to be performed and how.

After more development in this field, the use of robots in household may be common.

Scientists are working on technologies that can be incorporated in future robotic pets,

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which can enable the pets to better mingle with families, and also provide care and

protection.

viii. Future robotics systems may come up with benefits that we can't even imagine of. In

many films, the robotic hand has been showed, who knows it may become a reality in

the near future. The advantages of robotics are certainly predicted to grow in several

other fields over time.

6.2 Disadvantages

There are several disadvantages for robots. The main one is that robots are expensive to build

and maintain. Another disadvantage is that they have limited duties as they will only do what is

programmed and cannot think for themselves. A robot can have problems and not be able to fix

that problem, since it's not programmed to do that. Robots create massive job losses and usually

require more.

i. The main disadvantages of automation are:

ii. Causing unemployment and poverty by replacing human labor.

iii. Security Threats/Vulnerability: An automated system may have a limited level of

intelligence, and is therefore more susceptible to committing errors outside of its

immediate scope of knowledge (e.g., it is typically unable to apply the rules of simple

logic to general propositions).

iv. Unpredictable/excessive development costs: The research and development cost of

automating a process may exceed the cost saved by the automation itself.

v. High initial cost: The automation of a new product or plant typically requires a very

large initial investment in comparison with the unit cost of the product, although the

cost of automation may be spread among many products and over time.

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CHAPTER 7

CONCLUSION

1. Tongue Drive system (TDS) is a tongue-operated unobtrusive wireless assistive

technology,

2. which can potentially provide people with severe disabilities with effective computer

access and environment control. It translates users’ intentions into control commands by

detecting andclassifying their voluntary tongue motion utilizing a small permanent

magnet, secured On the tongue,and an array of magnetic sensors mounted on a headset

outside the mouth or an orthodontic braceinside.

3. The main aim of this project is to design and construct a tongue controlled robot and

deviceswitching wirelessly using RF technology. This device is portable and this system

operation isentirely driven by wireless technology. The user can control the Robot

directions with the simple tongue movement

4. .The control system consists of magnetic sensor and microcontroller. Microcontroller

collects data from the sensor and transmits the encoded data through the RF transmitter.

At receiver end RF receiver receives the data through the decoder and fed as input to the

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micro controller. The controller performs the corresponding actions i.e., Robot

movement.

REFERENCES

www.google.com

www.wekipedia.com

www.roboticworld.com

www.IEEE.com

www.naturalpowersource.com

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