smartcopter - eecs.ucf.edu
TRANSCRIPT
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SmartCopter
Matthew Campbell
Brian Williams
Alvilda Rolle
Group # 3
Senior Design
University of Central Florida
Sponsors:
Nelson Engineering Co.
Rogers, Lovelock, and Fritz Architecture
August 10, 2009
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Table Of Contents
Executive Summary 1
Chapter 1: Introduction 2
1.1. Project Narrative 2
1.2. Team Members/Sponsors 3
Chapter 2: Helicopter Description 4
Chapter 3: General Design 14
3.1. Detailed Project Description 14
Chapter 4: Subsystem Design 16
4.1. Chapter 4 Overview 16
4.1.1. Description 16
4.1.2. Objectives 17
4.2. Copter Stability System 18
4.2.1. Hardware 18
4.2.1.1. Power Management 18
4.2.1.1.1. Battery 18
4.2.1.1.2. Power Supply 19
4.2.1.1.3. Motor Control 20
4.2.1.2. Flight Surface Control 22
4.2.1.2.1. Servos 22
4.2.1.2.2. Accelerometers 24
4.2.1.2.3. Gyros 27
4.2.1.2.4. Ultrasonic Range Finder 29
4.2.1.3. Noise Filtering 30
4.2.1.4. Global Positioning System (GPS) 33
4.2.1.5. Microcontroller 35
4.2.2. Software 42
Chapter 5: Testing Procedures 47
5.1. Helicopter Flight 47
5.2. Hardware Connections 50
5.3. Ultrasonic Range Finder 52
5.4. Gyroscope 53
5.5. Accelerometer 53
5.6. SiRF Star III Chipset 54
5.7. HeliCam 55
5.8. SD Card Interface 55
5.9. Fully Integrated System 57
5.10. Testing Accommodations 59
5.11. Detailed Plan 62
5.12. Testing Locations 64
Chapter 6: Mounting Hardware 67
Chapter 7: Future Project Upgrade Possibilities 69
7.1. Potential Uses 69
7.2. Multi-Helicopter Coordination 70
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Chapter 8: Timeline 71
Chapter 9: Budget 73
9.1. Parts List 73
9.2. Funding 77
Chapter 10: Conclusion 78
Chapter 11: Appendix 79
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Executive Summary
Our project SmartCopter revolves around the design and production of a black box type
device. Attached to the bottom of an RC helicopter the device will record flight data to be
viewed later. The flight data will include position obtained from GPS and altitude. Also
included will be data regarding forces acting on the craft such as acceleration in the X,Y
and Z axis, as well as rotation such as pitch and roll. This data will then be saved to an
SD card where it can be viewed later using base station software. Once at the base station
this data will be analyzed graphically to provide a picture of the forces involved in the
flight. All the while the SmartCopter will broadcast video to a base station where it will
be recorded and later synced with the data. Thus aiding in analyzing the data recorded
earlier.
Along with functionality, our design needs to be conceptually viable as well. Our system
must meet a few requirements for this to occur. One such requirement is the need for
reliability. Our system must successfully complete the mission every time it is sent out.
A major aspect of its reliability will be the durability of the system. SmartCopter must be
capable of withstanding forces incurred during landing, whether it be in full control or
not, and still maintain its ability for a repeat use. Another issue facing our SmartCopter is
weight. As with any aerial vehicle, weight is extremely critical. Therefore the design
will incorporate the lightest possible components that will be necessary for the system to
take off, and land safely. Since components will be physically added to the helicopter,
placement of these additional components inside the shell of the helicopter is crucial.
Even distribution of the additional weight is necessary to maintain the balance integrity
of the helicopter.
Some other factors that will need to be addressed, but that aren‟t as crucial, will be
SmartCopter‟s ease of use, flight range, as well as the price. SmartCopter‟s user input
system needs to be as user friendly as possible. Along with user feasibility will be the
range of SmartCopter. The team will establish the range of the helicopter. Another issue
that will need to be addressed will be the cost of entire project. SmartCopter needs to be
moderately inexpensive within a total cost of $1000. Funding of up to $1000 will be
provided by SmartCopter‟s sponsors, with any additional costs being incurred by the
team members. Therefore it is of utmost importance to minimize the total cost of the
project.
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Chapter 1: Introduction
1.1 Project Narrative
1.1.1 [18] History:
In 1939 one of the earliest flight data recorders was created by François Hussenot in
France and was called the „type HB‟ flight recorder. It was created to measure altitude,
speed, and various other attributes attributed with flight. He managed to do this by using
88mm photographic film that was shown upon by a thin ray of light. This light was
controlled using mirrors that reflected the light based on the values from the sensors.
Since then flight recorders have been an integral part of aviation.The major driving force
behind the development of flight recorders stemmed from the need to investigate crashes
where witnesses were not available. This was the case in 1953 when a series of crashes
involving passenger aircraft led to an investigation of the cause. Without any witness the
need for a data recorder became evident and development began on a cockpit voice
recorder as well as a flight data recorder.
However it wasn‟t till 1960 that the idea of a „black box‟ data recorder caught on with
industry. This was largely due to budget issues and the primitive technology. In a few
years with increasing scrutiny from governments concerned about airline accidents the
black box data recorder was accept and installed on commercial jets. Today modern black
boxes have evolved into hardened capsules capable of withstanding intense shock, heat,
and water. Designed to withstand even the worst crashes the data recorded on these boxes
are vital to crash investigations and will be a part of air travel for as long as it exists.
1.1.2 Motivation
The motivation behind our project is to create a black box device to study the forces
involved with RC helicopter flight. With this knowledge we hope to understand how
changes in flight surfaces affect the overall flight characteristics. This could then be used
as a stepping stone to create an autonomous control system for the helicopter. By
analyzing the sensor data we can create assumptions as to how to control the craft.
One other reason for developing the black box is similar to the reason black boxes is
installed on full sized aircraft, to investigate accidents. With information about why the
craft crashed we can use that information to prevent future accidents. Also by studying
the forces involved we can try to understand the tolerances of certain components and
where structural integrity needs to be increased. Not only that but by recording the flight
data user error can be detected and corrected helping train rookie pilots in the operation
of the craft.
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1.2 Team Members/Sponsors
The team that has taken on this daunting task of creating SmartCopter consists of
Matthew Campbell, Brian Williams, and Alvilda Rolle. All three team members are
currently in their senior years at the University of Central Florida, in Orlando, Florida.
Matthew Campbell is a native Floridian who has had an great interest in computer
science ever for as long as he can remember. Matthew has also held interest in learning
various related electrical engineering applications. He is seeking a Bachelor of Science
in the field of Computer Engineering and has a minor in business.
Brian Williams has lived in the central Florida area for about 12 years. Brian‟s father
served in the United States Air Force for a total of 20 years before retiring. Due to his
father serving in the military, Brian‟s family has traveled extensively abroad. He has
lived at various Air Force bases throughout the United States and Germany. A majority
of his life was spent living on major Air Force installations that have a history of
extensive aerial technological advancements. A few of these installations include Wright
Patterson Air Force Base in Dayton, Ohio, Ramstein Air Force Base in Ramstein,
Germany, and Whiteman Air Force Base in Whiteman, Missouri, which was a secret
location of the SR-71 Blackbird and the stealth B-2 Bomber. As a child growing up in a
military environment, Brian has witnessed various sorts of air craft in action displaying
their amazing design and technology. However at the same time, he has witnessed the
devastation that can happen when things malfunction and go aria. Brian and his family
were at the famous air show in Ramstein, Germany on August 28, 1988 where two
airplanes collided mid-air, then came crashing to the ground. Brian‟s family were among
the spectators enjoying the amazing displays of aerial navigation. They happened to be
watching the show at the exact location where the fiery wreckage came crashing down. It
was the simple good fortune of being thirsty which drew his family away from the site a
mere 5 minutes prior to the crash. It was a collaboration of all his experiences growing
up as a military child which sparked Brian‟s interest in aerial aviation and in engineering
in general. Brian is seeking his Bachelor of Science in the field of Electrical
Engineering.
Alvilda (Allie) Rolle is a native Floridian. Her interest in electronics was inspired by her
father‟s knowledge of computers and printers. She would watch her father as he built
bare bone computers and repaired Hewlett Packard printers. From her father she
developed a love for computers and electronics. She initially wanted to pursue a
bachelor‟s degree in Spanish, but she changed her mind, and instead pursued Computer
Engineering. After a series of programming courses, she realized that she preferred
Electrical Engineering. She changed majors the next semester. Allie enjoys studying
languages. She is currently pursuing a minor in Spanish, and has become quite fluent in
it. She also enjoys traveling as often as she can. Allie has family members who have
helped solidify her interest in Electrical Engineering. She enjoys conversing with them
about technological advancements. After graduation Allie hopes to obtain a job in the
field of engineering. She eventually intends to attend graduate school in the possible
pursuit of law or architecture. In which both fields she can apply her electrical degree.
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Along with these dedicated team members, project SmartCopter has enlisted the
sponsorship of two prestigious engineering firms. The firms consist of Nelson
Engineering Co. of Merritt Island, Florida and Rogers, Lovelock, and Fritz Architecture
and Engineering (RLF) of Winter Park, Florida. Nelson Engineering Co. is an
engineering firm which was established in the early 1990‟s. They specialize in various
sorts of engineering practices including Aerospace, Electrical, Mechanical, Civil,
Chemical, Industrial, Environmental, and Fire Protection Engineering. Nelson
Engineering Co. focuses a great deal of resources on product research and development,
with extensive work done with NASA and the United States Air Force.
The other sponsor for the SmartCopter project is Rogers, Lovelock, and Fritz
Architecture and Engineering (RLF). RLF is an Architecture, Planning, Engineering, and
Interior Design firm, and the employer of team member Brian Williams. RLF was
established in 1935 by James Gamble Rogers II. RLF has done extensive design
including various religious, healthcare, educational, and Department of Defense projects.
RLF is a naturally recognized firm that has received a number of awards for their design
work, as well as their various volunteer efforts. RLF is one of the oldest practicing
design firms located between Jacksonville and Miami. This is due in part to its
exceptional staff, and its long roots in the Central Florida community.
Chapter 2: Helicopter Description
The helicopter is the focal point of our project, therefore selecting the right RC helicopter
to meet our requirements was vital. Originally we considered smaller RC helicopters with
two counter rotating main rotors such as the one shown in Figure 2.1. Their ease of
control and inherent stability was appealing at first. However after researching further we
found that with the dual rotor configuration forward flight against wind was slow to
impossible, so it did not meet our requirements.
[9]Figure 2.1
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From there our research led us to more traditional RC helicopters with a single main rotor
and a tail rotor to balance the main rotors torque. The single rotor helicopter would be
more difficult to control than the counter rotating rotor helicopter but would fare much
better in windy conditions. Therefore to meet our wind requirements we chose this layout
for our helicopter.
The next decision we had to make was on the design of the tail rotor system. Many RC
helicopters use a small electric motor that is completely separate from the main rotor
drive. While this design does have some advantages, such as being easier to manufacture,
there are also some drawbacks. For example, tail rotor motors are prone to failure and are
less precise in their thrust generation. We decided that for the best control of our
helicopter we would choose a helicopter with tail rotor driven by the main rotor‟s motor
and the pitch of the blades will change the amount of thrust generated.
With the fundamental design of our helicopter chosen we could start talking about the
actual flight dynamics of they helicopter. Along with motion in the X, Y and Z axis we
must also consider pitch, roll, and yaw also known as Tait–Bryan angles or Euler angles
shown in Figure 2.2. Pitch corresponds to rotation about the y-axis and will be defined as
θ; yaw corresponds to rotation about the z-axis and will be defined as ψ; roll corresponds
to rotation about the x-axis and will be defined as φ.
Figure 2.2
In order to rotate or move the helicopter the flight surfaces on the main rotor and the tail
rotor change their pitch to create an unequal force producing the desired motion. The
cyclic control, which is similar to the flight stick in an airplane, is used to control the
pitch and roll of the helicopter by varying the pitch of the main rotor blade. The yaw rate
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and heading is controlled by the pitch of the tail rotor. Finally motor RPM and collective
pitch, the overall angle of attack, of the main rotor blades control the lift generated and
altitude of the helicopter.
By combining these different changes to the control surfaces we can create a wide variety
for our helicopter. For example pitching the nose downward and increasing the
throttle/collective will propel our helicopter forward while maintaining altitude.
Due to the size and relatively low weight the helicopter is very sensitive to control inputs
and any air flow disturbances are magnified, creating a very high bandwidth system.
Unstable air just below the main rotor, called rotor wash, affects lift on all of the flight
surfaces and becomes more unstable after passing past the fuselage of the helicopter. This
problem becomes magnified at ground level and causes problems at take-off and landing
so accurate data collection during this time is critical to understanding the flight of the
helicopter.
The first series of measurements we will take of the helicopter will be while it is in a
hovering mode. In this mode the helicopter maintains its current altitude and position,
making corrections for any disturbance introduced to the system. In order to maintain the
altitude we balance the lift generated by the main rotor and the gravitational force.
To maintain the heading we balance the torque generated by the main rotor and the force
generated by the tail rotor, using the same equation for lift as before. Finally the
helicopter must balance the pitch and roll in order to maintain its position. This is made
more complicated due to the fact that the spinning main rotor blade provides gyroscopic
precision which causes a phase lag in the system, which should evident when analyzing
the data received from the helicopter.
In order to simplify the modeling process we will break up the model relating inputs to
helicopter position into three parts shown in Figure 2.3 and study each block in depth.
The first block will model the flapping dynamics of the rotors and relate the control
inputs to the thrust generated by the rotors as well as the orientation of the main rotor
related to the body of the craft. This will then drive the inputs for the force torque
equations in the second block which will output the sum of the forces and torques on the
helicopter. Finally the last block will model the helicopter as a rigid body and define the
position and orientation of the helicopter.
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Figure 2.3
The first block that we‟ll look at in depth is the one containing the rigid body equations.
In order to transform the force vectors stated in the frame of reference of the body of the
helicopter to the spatial frame we define the center of gravity in we need to derive a
coefficient matrix. These rotation matrices are defined by Bak[4]
and are shown below in
equations 2.a. Where θ1 is the roll angle, θ2 is the pitch angle, and θ3 is the yaw angle. By
combining these equations we can relate the spatial frame of reference to the body frame
of reference as shown also in equations 2.a. Alternatively by taking the inverse we can
relate the body frame to the spatial frame.
Equations 2.a[4]
Now that we have the angles to define the orientation of our helicopter we can look at the
time derivative of these angles, called Euler rates which will represented by . We can
also represent these values as an angular velocity vector represented by ω. The value of ω
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can be calculated with equations again provided by Bak[4]
shown in equations 2.b, and the
same can be said for the inverse also shown.
Equations 2.b[4]
We now need to define the angular acceleration of our helicopter as it relates to torque
put on the rigid body of our helicopter. First we‟ll define an inertia matrix I such that we
can find the value of the angular momentum vector H. The relation as well as the inertia
matrix is defined below in equations 2.c provided by Wie[5]
.
Equations 2.c[5]
This combined with the equations for torque of a rigid body about its center of gravity
shown in equations 2.d gives us a final relation between the torque vector, written as τ or
, and the angular velocity vector shown also in equations 2.d provided by Wie[5]
.
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Equations 2.d[5]
Describing the translatory acceleration only involves one equation where F, the force
vector applied to the helicopter, is related to V, the velocity vector of the helicopter, as
shown in equations 2.e below.
Equations 2.e
With our rigid body block defined we can move on and look at the second block, the
force and torque equations. There are three main forces acting on the helicopter: FMR
which is the force generated by the main rotor, FTR which is force generated by the tail
rotor, and finally the force of gravity is taken in to account represented by FG.
The force of the main rotor is a function of the thrust generated along with the orientation
of the plane of the main rotor‟s blades, B1c and B1s. This is shown in Figure 2.4[6]
where
HP is the initial plane and TPP is the pitched plane. From this we can derive force
equations for each axis shown in equations 2.f below.
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Figure 2.4[6]
(Top B1C; Bottom B1S)
Equations 2.f
The next force we look at is the one created by the tail rotor. Since there is no pitch
involved, the tail rotor‟s force is equal to the thrust created by the tail rotor in the positive
y direction.
Finally we have the gravitational force acting on our helicopter. We can represent this as
a vector by considering our Euler angles from before. This is shown in equations 2.g
below derived from equations 2.a.
Equations 2.g
Combining all terms we come up with the following force vector matrix shown by
equations 2.h.
Equations 2.h
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Similarly we will define torque vector by breaking it up into three components shown in
equations 2.i, torque generated by the main rotor, torque provided by the tail rotor, and
finally torque generated by the resistive air drag on the main rotor.
Equations 2.i
The first of which, the torque generated by main rotor, is shown in the equations 2.j
below where h is the distance from the COG to the main rotor along the z-axis, l is the
distance from the COG to the main rotor along the x-axis, and y is the distance from the
COG to the main rotor along the y-axis.
Equations 2.j
Next the torque generated by the tail rotor is considered. Using the same nomenclature
for distance used for the main rotor we can derive equations 2.k similar to the one just
shown.
Equations 2.k
Last we need to calculate the torque created by the aerodynamic drag of the main rotor.
However accurately modeling the drag on the main rotor can be a very complex problem
so we will use a model as described by Koo et al. [8] shown in equations 2.l below.
Where Qi is the drag created, Di describes the drag created when blade pitch is zero, and
Ci describes the relation between drag and thrust generated. Taking into account the pitch
of the main rotor blades we can complete the torque matrix also shown in equations 2.l.
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Equations 2.l
Combining all of our torque equations and inserting them into equation 2.i we have our
torque matrix for all our components shown below in equations 2.m.
Equations 2.m
The final block we‟ll take a look at is the block containing the flapping dynamics for the
main rotor and tail rotor, specifically how much thrust is created. The equation for the
thrust generated by the main rotor according to NASA‟s Minimum-Complexity
Helicopter Simulation Math Model is shown in equations 2.n[3]
where ρ is the density of
air which will remain constant throughout the flight. The rotor‟s angular rate will be
defined as Ω, R will be defined as the radius of the blade, and B will be the number of
blades. The lift curve slope is a constant and will be defined as a and c is the chord of the
blade. Finally wb is the velocity of the main rotor blade relative to the ambient air and vi
is the velocity of the flow through the plane of the blades and is derived below.
Equations 2.n[3]
By ignoring the blade twist, shown as θtwist, we can simplify the derivation of the wb
shown by equations 2.o[3]
.
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simplifies to
Equations 2.o
[3]
As you can see in equations 2.o that the thrust of the main rotor is merely a function of vi
and vi is a function of the main rotor thrust, meaning that these equations are recursively
defined. These values feed back into the equation after a certain amount of delay, 5
iterations is enough to ensure that the values have settled according to NASA‟s model [3]
.
Next we need to define the thrust produced by the tail rotor. In order to simplify this we
will assume that yaw will be controlled by the magnetic compass such that a single
heading is maintained.
We show how the tail rotor thrust is derived below in Equations 2.p. Solving for the tail
rotor force and adding in the force associated with the input force upedal we have our
equation for tail rotor thrust.
Equations 2.p
With all of this we have a general description of the flight characteristics of our
helicopter that we can compare our physical measurements to later in the project.
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Chapter 3: General Design
3.1 Detailed Project Description
SmartCopter began as a modified 6-channel RC helicopter designed to work
autonomously. The helicopter we chose, the Esky Belt-CP 450 has built in servos and
gyros. Its very light structure is built for 3D maneuvers. With this initial design our aim
for SmartCopter was to enhance its structure so that it could not only fly automatically
but also take surveillance videos, and sense unwanted objects to avoid collisions.
However due to time constraints, lack of professional flight training and other factors,
SmartCopter has emerged as a data logger. With the helicopter component a successful
SmartCopter mission would have begun by a successful upload of waypoints via
computer software. Once the aircraft was in automatic mode, it would begin its flight
sequence by launching from the start pad. It would check its GPS coordinates and
commence flight plan.
The design was modified instead to eliminate the autonomous part, but still use the sensor
readings as stored media within a data recording device. With the helicopter component
by using its x,y,z coordinates it would arrive at its destination by receiving the
longitudinal and latitudinal points through its GPS flight path. During its flight sequence
the screen would have displayed GPS coordinates for every point of the mission. There
would also have been a mini video recording the mission. The ultrasonic range finder
would have ensured that SmartCopter wasn‟t too close to the ground or other moving or
nonmoving objects. If a surface or object was detected a signal would have been sent to
the microcontroller which would then be sent to the gyro, so that the aircraft could adjust
its direction.
These design criteria will still be actively a part of the data logger but as generated values
being referenced by each sensor. They will not serve as control devices for the helicopter
except via test flying which consist of a person holding the helicopter and rotating a room
with it in order to generate those values. Time permitted training will be underwent to
adequately learn how to control the helicopter. Ideally as an autonomous device when
SmartCopter encounters objects it would pause during its flight sequence and hover,
while adjusting its tail to adjust to the infraction. In which case it would either move up,
down, backwards, left, or right to avoid a collision. The ultrasonic range finder would be
especially useful because during missions that may take place in a public area, there is
constant action. Once SmartCopter reached its waypoint destination the user would
receive a text message indicating the mission is complete. If the user was tracking the
flight progress via a computer then the screen would light up on SmartCopter and the
message would also show up on the computer device indicating a completed mission.
SmartCopter then would repeat the mission but to return to its starting position. The
video would still be in record mode.
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The data logger will have a similar display unit. It will have a user input LED in which
the user can select each device and see the data it‟s storing or the stored data. During an
autonomous mission the completed video can be removed and played or used for
additional purposes. The video will have efficient memory card space to record the entire
mission. If time permits the video component will be included in the data recording
device. If at any time SmartCopter encounters problems, the emergency override will
kick in. The user will be able to stop the data input in mid sequence. SmartCopter will
need the servos, gyros, accelerometers, and the electronic compass to control its flight
operations. The servos are used to correct any sudden movement that the gyro detects.
The servos will correct any negative feedback that is detected. The gyros will detect any
negative feedback that SmartCopter encounters. Together they ensure that SmartCopter is
not encountering any detrimental feedback that may cause serious damage, or that may
interfere with its direction. The gyro will ensure that SmartCopter is always pointed in
the desired direction because it detects unwanted movements of the tail, and corrects
them. With autonomous flight these sensors would each be used to maintain control of
the aircraft, however their values will be collected, stored and viewed by the user and
used for their own purpose. The electronic compass will no longer be necessary with the
updated design modifications.
The accelerometer will measure the direction of acceleration of SmartCopter. It will also
ensure that SmartCopter is oriented correctly. Additionally it will sense vibrations and
shock. This device will constantly monitor SmartCopter‟s velocity. It will be able to track
how fast it should be going, and whether it‟s traveling too fast.
Although the GPS function can measure direction, it is fairly inaccurate when the aircraft
is not in motion. But with the data logger it is less of importance to maintain constant
direction. The values are more important.
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Chapter 4: Subsystem Design
4.1 Chapter 4 Overview
4.1.1 Description
Chapter four is exclusively about the subsystem design of SmartCopter. It contains three
sections the Copter Stability System, the GPS Guidance System, and the Camera System.
The Copter Stability System begins with the hardware surfaces. It provides a conceptual
description for each component as well as practical applications for them. The Copter
Stability system contains three subsystems including Hardware, Software, and
Emergency Override. There are four subsections of Hardware, Power Management,
Flight Surface Control, Noise Filtering, and the Microcontroller.
Power Management addresses the battery specifics, the power distribution, and the motor
operations. It provides details of the battery chosen to power SmartCopter, the Lithium-
Polymer battery. It describes the various advantages of using this particular battery. Then
it addresses the importance of maintaining a balanced power system by not applying too
much voltage to the system. The final subsection in Hardware is the Motor Control
section. Here the brushless motor is examined. It‟s compared with its predecessor the
brushed motor, and it‟s improvement in efficiency than the brushed motor. The Power
Management section contains the power behind SmartCopter.
The Flight Surface Control section addresses the various components that are required to
maintain flight stability. Although the servos are of less concern for the data logger, they
are correction devices that correct the error feedback and maintain the angular position of
the shaft. The accelerometers are then discussed and detailed in great length. They are
devices which measure activity acceleration due to gravity. SmartCopter will operate
with piezo-electric accelerometer. This section also includes the gyros. The gyros are
used to monitor the direction of the head, and ensure it‟s directed in the correct direction.
It also addresses the two types of gyros, the heading hold and the yaw rate. The next
component addressed is the electronic compass. The final section in the Flight Surface
Control segment contains info on the ultrasonic range finder. This device is used to
measure the distance between moving and/or non moving objects.
The Noise Filtering subsection briefly describes the Low-pass, High-pass, and Band-pass
filters. SmartCopter will encounter induced noise interference. It‟s possible that it will
exist between the transmitter and the receiver, and other electronic components. These
filters are often used to attenuate unwanted noise feedback. The Microcontroller is the
base, where the components connect together. It‟s the inner computer within SmartCopter
that‟s designed for smaller applications such as this. This embedded system contains a
CPU (central processing unit), a clock generator, memory storage device (RAM), an
analog-to-digital converter, and other serial communication interfaces.
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The next subsection of the Copter Stability System is the Software department. Software
will need to be written for each flight operation, the take off, the landing, the hovering,
and the traveling in motion. Stabilizing SmartCopter will be a tremendous part of this
design. Once SmartCopter has been stabilized, then the above functions will be
programmed in order to enable for secure take off functionality. Each division of the
Software section is important to completing an operational flight mission. These
operations would have been necessary to maintain autonomous flight, however because a
flight sequence will possibly consist of one person circling a room, they are of less
importance. The second chapter of the Subsystem Design is the GPS Guidance System.
This section is divided into four parts: the User Waypoint Input, the Accuracy
Requirement, the Hardware, and the Software.
The User Waypoint Input section addresses how the user would input the desired
destination by inputting the corresponding waypoints. For SmartCopter to be as
operational as possible then it will need to be as accurate as possible. Error will be
present, but ideally the percentage of error will be desired to be as little as possible. There
is a Hardware section similar to the Copter Stability System. The Hardware section will
contain information and developmental procedures for the GPS, and the Electronic
Compass. It will address how both components will work independently but together to
maintain SmartCopter is always on course, providing some additional information from
the Copter Stability System chapter.
Both components of SmartCopter will need software development. Within the Software
division the Waypoint following will be described. The last subsection of the GPS
Guidance section is the Camera System. The technology behind the video system of
SmartCopter will be probed into. The section includes how the video recording
component will operate. Originally SmartCopter was to be designed with video
capabilities of recording the entire flight mission. However to design changes the data
logger will not include the video recording device. Each section and corresponding
subsections will be addressed in greater details in the upcoming chapters. It addresses the
role each component will play within SmartCopter‟s design.
4.1.2 Objectives
The objective of Chapter 4 is to provide in depth descriptions of the internal operations of
SmartCopter. The goal is to provide as much information about the inner hardware and
software of SmartCopter. Being a fairly new concept to some of the members, there was
a lot of research that needed to be done. There are related aircraft in the field now. When
SmartCopter is complete, it will be an automated helicopter. It‟s internal design will be
similar to the research provided in this chapter.
This chapter provides visuals to assist the user and the reader with the physical and
conceptual knowledge behind SmartCopter. It provides formulas so that the user and the
reader have a somewhat clear understanding of the conceptual concepts behind the
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operation of SmartCopter. The objective of this chapter is to also provide descriptions of
the operation of each component, and to provide information on how these components
will be implemented.
4.2 Copter Stability System
4.2.1 Hardware
4.2.1.1 Power Managment
4.2.1.1.1 Battery
The SmartCopter will be battery powered by a Lithium-Polymer (Li-Po) battery,
specifically the 11.1V 1800mAh 20C high capacitance Li-Po battery. The Li-Po is not
only cheaper than the Li-Ion, but is being used more frequently in cell phones, PDA‟s,
laptop computers, Radio-controlled aircraft, vehicles, and IPods. Some companies are
even considering using the Li-Po in future battery electric vehicles. The Li-Po is
undoubtedly light weight, cost effective, and due to the rechargeable capabilities offers an
increased run time, which will come in handy for SmartCopter missions.
For the purpose of this design we will use two Li-Po batteries. While one is in use the
other will recharge itself, and vice versa. For future use the design will need to be
adjusted, because the Li-Po cannot be exposed to too much heat. One of the future uses
was locating civilians in the midst of fire. The Li-Po also has some internal resistance
issues.
The internal resistance of a Li-Po or Li-Ion battery is relatively high in comparison to
other rechargeable chemistries. The increased terminal resistance is a time dependant
process. Once the internal resistance has increased it can often cause voltage drops at the
terminal, which then reduces the amount of maximum current being extracted from the
battery. Eventually the battery reaches a point in which it can no longer operate the
device for a period of time. All setbacks aside the Li-Po in comparison to the Li-Ion
maintains a greater life cycle reduction rate.
One main advantage for using Li-Po over Li-Ion is that aside from possible explosion if
over charged, unlike other batteries they can be thrown around, roughly handled, run over
by vehicles and still not suffer from explosion. If SmartCopter experiences unexpected
turbulence the Li-Po battery will not explode from sudden shifts in elevation or density.
How fast the battery can discharge is based upon the maximum current capacity. This
battery has a 20C capacity. It should discharge in 1/20 hours or three minutes. The
battery life according to one formula is approximately 5.4 minutes:
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1800mAh = 1.800Ah
20C = 20A supplied current
1.800Ah x 60min = 108
108/20A = 5.4 minutes
Li-Po batteries have voltage varies between approx. 4.23(charged) and 2.7(discharged).
The figure below is a photograph of a Li-Po battery provided by Wikipedia.
Lithium Polymer battery
4.2.1.1.2 Power Supply
The power system for RC helicopters consists of three elements, the battery, the speed
controller, and the motor that is responsible for driving the rotor blades and gearbox.
The battery power is important because each component that is added to SmartCopter
will need battery power. So in addition to powering the built-in components the
additional components will also require power, such as the electronic compass. Once
again SmartCopter will be battery operated by a rechargeable Li-Po battery. It‟s a
relatively new development, having replaced the Li-Ion battery. It‟s lighter and more
powerful, which is what SmartCopter needs. And its rechargeable capacity is excellent
because all we‟ll have to do is charge it up and resume flying. For the sake of time
limitations we hope to have two Li-Po batteries, so that while one is recharging, the other
can be in use.
SmartCopter without the design additions flies for approx 15 minutes. How all of the
design specifications will affect the time, is difficult to say. But by investing in a second
battery we can cut out some of the wait time in between test flights. There will still be a
wait time because the battery takes approximately 30 minutes to recharge, however with
the second battery SmartCopter can be in flight for 10-15 minutes of that charge time.
In RC helicopters the battery is the power source. The higher the battery, the more power
there is available. Within the helicopter, working with the motor is the electronic speed
controller. This c component interprets the control signals coming from the radio receiver
and transfers the battery power to the motor which then controls the speed the user wants.
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The electronic speed controller works as a buffer to fluctuate the speed of the brushless
motor. This function takes place between the motor and the battery.
The final component the motor, converts all electric power to mechanical power. With a
brushless motor the power cannot be applied directly to it, thus the speed controller
causes the motor to rotate by powering each phase of the brushless motor in succession.
SmartCopter gains efficiency from the brushless motor, because of its maintenance free
built, and its soundless structure. SmartCopter can prospectively stealthily hover behind a
person without being detected. For future use this feature will be highly invaluable. For
example for military uses an efficiently silent device will be more advantageous than a
noise filled design. Using the brushless motor affords this. Although it cost more, it‟s
more powerful than the brushed motor.
SmartCopter will need to maintain a balanced power system by not overloading each
individual component. As it is being built, more than likely we will encounter many
necessary adjustments that need to be addressed. Some of which may include applying
too much current or voltage, because if too little is applied then the device will not power
up. If too much is applied then something may burn out. The more power applied the
faster it may fly, but the shorter the battery life time.
4.2.1.1.3 Motor Control
The SmartCopter will be driven by an Esky 450 3800KV brushless motor. Thanks to
technology advancement the brushless motor has almost explicitly replaced the brushed
motor. The brushless DC motor (BLDC) consists of a set of electromagnetic motors on a
non rotating stator and a set of permanent magnets on a rotor. When it‟s connected to a
DC source, the electromagnets charge as the shaft turns. With these adjustments the
brush-system is eliminated and replaced by an electronic controller. The controller then
performs the same power distribution function as the brush-system except using a solid
state circuit.
With the brushed motor the electromagnets are located on the inside of the motor as part
of the armature. The armature rotates, hence being referred to as the rotor. The permanent
magnets are located on the outside, as stationary objects or the stator. Once electricity has
made contact with the electromagnet it creates a magnetic field inside the armature which
repels and attracts the magnets in the stator. The armature must spin through 180 degrees.
In order for it to maintain spinning, brushes are used to change the polarity of the
electromagnets.
Although the brushed motor was efficiently workable, the system was gravely in need of
upgradeable developments. All of which will help SmartCopter run as smoothly and as
efficiently as possible. The BLDC eliminates the use of brushes. Not only do brushes
limit the maximum possible speed of the motor but they also eventually run out. Once
they‟ve run out, they obviously need to be replaced. By using brushes it also limits the
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number of poles being emitted by the armature. In addition by placing the electromagnet
on the outside instead of the inside makes its cooling process easier.
Additionally as if that‟s not enough the BLDC provides higher efficiency, and increased
reliability. It reduces noise and eliminates the ionizing sparks created by brush contact.
The electromagnets will receive cooling by conduction, which will allow the internal
motor to be enclosed and provide protection from foreign substances. The BLDC also has
a longer lifetime than the brushed motor, which will support a long lifetime for
SmartCopter. The brushless motor also consumes less energy, and with a reduced EM
interference it helps reduce radio interference.
The disadvantage of using the BLDC however, is the cost. Although the motor is more
efficient than its former model, it is still not greatly used in the commercial sector. It also
requires a very complex electronic speed controller, which is used to basically vary the
drive motor‟s speed and direction. Combine these two important criteria together and
they both more than likely contribute to the high cost of the BLDC.
Cost aside, the brushless motor is our best choice. Not only is it included with the
helicopter purchase but given the data presented and additional research SmartCopter
should maintain superb motor efficiency with this model of the brushless motor.
The figure below is a Brushless Motor property of Howstuffworks.com
Brushless Motor from Howstuffworks.com
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4.2.1.2 Flight Surface Control
4.2.1.2.1 Servos
A servo is an automatic device that generally uses error sensing feedback to provide
correction to the mechanism performance. Servos are generally used in an automatic
system where the error-correction or feedback signals assist controlling the mechanical
position or other parameters. A servo mechanism is unique in that it controls a specific
parameter by the command of the time- based derivative of that parameter. Most servos
are commonly electrical. There are other types of servo use as well, pneumatics, magnetic
principles, and hydraulics. Within helicopters, servos are electrical devices that help
control flight.
There are two types of servos, standard and digital. SmartCopter will be using a digital
servo because it operates more efficiently by eliminating the “deadband” which is found
in the standard servo. By removing the “deadband” the rate at which the servo receives
pulses increases dramatically from approximately 50 to 300 pulses. On standard servos
the rate is around a maximum of 50 pulses per second.
The standard servo is less efficient for SmartCopter, because of the exceptionally fast
rate within the standard RC servo that allows minutely small movements from the control
stick to have no affect at all. This has been known as a “deadband” on the control stick,
where no servo movement takes place. This causes no problems for most other RC
designs; however for 3D aircraft any small delays can cause a collision. Which is why the
digital servo is a much better choice for SmartCopter, the resolution increase provides the
helicopter with more precise servo operation.
RC servos are small electro-mechanical devices that are built out of a few gears, an
electric motor and a head in which a wheel or arm can also be attached. This device
responds to a control signal by converting the angular momentum of the servo arm to the
linear movement of the control surface. Servos are designed to maintain or hold position.
Because the aircraft is in constantly interacting with external forces, servos are needed as
grounds for holding the current position; otherwise SmartCopter would be able to remain
in one location for a period of time. Without the servos the external forces would set
control surfaces to undesired and unwanted positions. The command is fulfilled when the
user communicates what angular position to move to, the servo then rotates and holds the
desired position until it receives a new command.
Three wires control the RC helicopter servo: one sends the signal, which controls the
servo, two that provide the DC electricity which is needed by the motor. The three wires
are a ground wire, a signal wire, and a power wire. Servos are normally connected into a
three pin-connector, radio receiver. The servo works by receiving a series of pulses sent
over a control wire that control the angle of the actuator arm. The pulses must be
consistent to gain accurate information on the angle. The signal wire carries a Pulse
Width Modulation (PWM) signal, which consists of a varied 1-2ms pulse repeated at fifty
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or more times per second. The servo will move to -45 degrees by a 1ms providing it has a
90 degree range of motion. A 2ms pulse will shift the servo to +45 degrees. A servo pulse
of 1.5ms will shift the servo to its “neutral” position or center, 90 degrees.
The electric motor inside the servo is mechanically linked to a potentiometer. Once the
servo receives the PWM signals, they have been translated or converted into positional
commands by the internal electronics of the servo. When the servo receives the command
to rotate, the system powers the motor until the resultant commanded position is reached
by the potentiometer.
There are several specifications that the servo is comprised of: torque, speed,
dimensions, weight, bearings, gears, and the motor. The torque measures the “strength”
of the servo, or the amount of “push” it holds. The torque‟s rating states the amount of
force the servo can exert. Naturally the higher the number, the more force the servo
exerts or the stronger it is. The bigger the aircraft the higher the torque servo, in general
the servo size increases with rated torque.
The speed of a servo is determined by the number of seconds that are taken to move a
specific amount of rotation, generally 60 degrees. The speed measures how quickly the
servo is able to move from one position to another. High speed servos in general are more
expensive than standard ones but are more efficient for 3D helicopters and other aircraft.
The dimensions of a servo are increased with the amount of torque that is provided.
Although SmartCopter is a 3D helicopter it must still maintain a certain weight
restriction. The servo should be strong enough to handle the demands successfully and
light enough to not add too much additional weight to the design structure.
The support of the main shaft can be handled by bushings or bearings. Standard servos
are generally supported by bushings, and larger more heavy duty servos are supported by
bearings. The bearings cost more than the brushes but are more durable. The gears of
most servos are either metal or nylon. Metal gears weigh more and wear over time but
they do not “strip” or shred, which is the cause of many RC helicopter crashes. Many
higher end servos use metal gears. In additional to metal and nylon there is karbonite and
titanium as well. The karbonite is approximately 4 times stronger than the Nylon material
and it offers better wear resistance in comparison to the metal material. The titanium gear
is considered to be the best on the market. It offers no wear and tear at all. Of course with
the increase in performance there is always the increase in cost. For SmartCopter and
other hobby based RC aircraft, the nylon or metal material should work well. Figure 1
and 2 are photos of RC servos provided by Wikipedia.
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Figure 1 Figure 2
Figure 1: RC Servomechanism Unassembled
Figure 2: RC Servomechanism. 1. Electric motor 2. Position feedback potentiometer 3.
Reduction gear 4. Actuator arm
4.2.1.2.2 Accelerometers
Conceptually accelerometers are devices that measure the acceleration, or the force
being experienced due to gravity‟s freefall. More advanced models also detect direction
and magnitude of the acceleration as a vector quantity, which can be used to sense shock,
vibration, and orientation. Accelerometers can be used to determine the angle at which
the device is tilted with respect to the earth, by calculating the amount of static
acceleration it experiences due to gravity.
Accelerometers also known as electromechanical devices have many uses. For
SmartCopter its purpose is to help it understand its surroundings. It helps determine its
orientation, whether it‟s driving uphill, or downhill, or flying horizontally. Other uses
include health monitoring systems. Accelerometers are used to rotate equipment for
machinery health such as fans, compressors, pumps, rollers, and cooling towers. They
help cut costs by reducing downtime, and by detecting conditions such as rotor
imbalance, gear failure, shaft misalignment, or bearing fault. Accelerometers help
improve safety in plants around the world. Without these detection devices the plants and
other technologies can result in costly repairs.
There are several categories of accelerometers. The three different technologies consist
of piezo-electric accelerometers, piezo-resistive accelerometers, and strain gage based
accelerometers. There are also different designs of accelerometers. There is the shear type
design, the flexural design, the single ended compression design, the isolated
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compression, and the inverted compression. Accelerometer types include the premium
grade, the high vibration, the triaxial, and the industrial grade.
The premium grade accelerometers use a low noise circuitry to produce a top quality,
low noise accelerometer. They are made from top-rate crystals, and their stainless steel
case is securely sealed against the environment, to protect it from harsh industrial
environments and exposure to weather related causes. The design of the high vibration
accelerometers is a bit different in that it is used to supervise high vibration levels. They
can supervise vibration levels up to 500 g‟s. The high vibration accelerometer is designed
for use on shaker tables, heavy industrial machine tools, and vibration labs due to its stud
mount design. The tri-axial accelerometers measure the vibration in the three axis, X,Y,
and Z. They consist of three crystals uniquely positioned so that each axis experiences a
crystal‟s reaction. The output consists of three signals, in which each one represents the
vibration from a different axis. The fourth type is the industrial grade. These
accelerometers are most common from machine tools to paint shakers. They come in
different models and are also sealed against the weather and industrial environments.
An IEPE accelerometer is a class of accelerometers that have built in electronics. It
stands for Integrated Electronics Piezo Electric. This class of accelerometers particularly
has low impedance output electronics and they work with two wires to provide a constant
current supply. Compared to the three wire accelerometers the two wire ones are easier to
install, cheaper to purchase, they can travel over long cable lengths, and contain a wide
frequency response.
Additionally there exist two types of piezoelectric accelerometers. The first is the low
impedance output accelerometer and the second is the high impedance charge output. The
low impedance accelerometer has a small built-in FET transistor and micro-circuit that
convert the charge from the charge accelerometer at its front end, into a very low
impedance voltage which is used with standard instrumentation. The high impedance
accelerometer uses the piezoelectric crystals to produce an electrical charge that is sent
directly to the measuring instruments. For this design the output charge demands special
instruments and accommodations which are often located in research facilities. The high
impedance accelerometer is often used where low impedance designs are unsuccessful.
Accelerometers are often used to measure the vibration and motion of structures that are
exposed to dynamic loads. Dynamic loads originate from a variety of sources including
earthquakes, wind loads and wind gusts, and human activities which consist of walking,
running, dancing, and skipping. They have also been used in sports watches that help
determine the distance and speed for the runner wearing the unit. Accelerometers are also
used as motion sensors for navigation systems. SmartCopter will need the accelerometer
to calculate continuously the position, velocity, and orientation of it without external
forces being needed. This is part of the Inertial Navigation System (INS) also known as
the inertial guidance system.
Within SmartCopter the accelerometers work alongside the gyroscopes to calculate the
necessary tilt. Within automobiles accelerometers are used as detection devices in order
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to deploy the airbags. In order to determine when a collision has occurred and the degree
of severity of the collision, the accelerometers are used to detect the swift negative
acceleration of the automobile. They can also be found on many personal electronic
devices such as Apple iPhone, the Blackberry Storm, and the Sony Ericsson W910i
amongst others.
The latest gaming system the Wii also contains accelerometers in its remote system. The
remotes contain three-axis accelerometers to sense movement, which is a complement of
its pointer functionality. I have played the Wii, and playing with remotes that have
excellent pointer functionality makes for an enjoyable experience. It would be a stressful
game if the remotes didn‟t point where the user aimed. The accelerometer design makes
the game more realistic.
Accelerometers are also built into laptops in case of mishaps. This has recently begun
with IBM and Apple. If the laptop accidentally drops, the accelerometer detects the
unanticipated freefall simultaneously, and switches the hard drive off so the heads are left
intact and not shattered.
The important specifications for an accelerometer consist of: bandwidth, sensitivity,
analog vs. digital, grounding, and buffering. The bandwidth represents the number of
times per second a reliable acceleration reading is taken. SmartCopter will probably use a
very high bandwidth because it will be a fast moving aircraft. In general the more
sensitivity there is the better. Sensitivity is the known output voltage produced by a
specific force, which is measured in g‟s.
High output accelerometers are used to measure any low level vibrations, while low
output accelerometers are used to measure any high vibration levels. Temperature
sensitivity is the output voltage for each measured degree.
SmartCopter will probably use digital accelerometers which use PWM for their output.
Analog accelerometers output an acceleration that is proportional to continuous voltage.
For the digital accelerometers there will exist a square wave of a specific frequency, and
the amount of acceleration will be proportional to the measure of time the voltage is high.
Figure 1 is an accelerometer designed by the Archimedes Automated Assembly Planning
Project at Sandia National Laboratory. Provided by Wikipedia
Figure 2 is Triple Axis Accelerometer Breakout- ADXL 335. Provided by Sparkfun.com
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Figure 1: Property of Wikipedia Figure 2: Property of SparkFun.com
4.2.1.2.3 Gyros
The gyros are essentially important to SmartCopter because their job is to ensure that the
direction of the nose is pointed in the desired direction. The reactive torque of RC
helicopters is constantly changing. Any decrease or increase in the pitch or engine speed
of the main rotor blades results in a change in torque. These changes are often caused by
wind gusts and are constantly responsible for trying to spin the helicopter.
When RC helicopters rotate on their yaw axis the direction in which the nose points
changes. The yaw gyro in effect helps control unwanted movement. When any undesired
rotation is detected the yaw gyro automatically corrects it. Without the yaw gyro, even if
SmartCopter is flying as straight as it possibly can, it will still experience drifting and
rotating from left to right. Formally the only type of gyro available was a mechanical
device; however they used up an enormous amount of battery power and were quite
heavy. Today most helicopter designs use piezo gyros.
Unlike the mechanical gyro, the piezo gyro does not function by utilizing moving parts.
Instead a piezo-like element is placed on either side of a triangular crystal. This piezo
element is found in many watches as the beep sound for the alarm function. Because the
piezo element not only makes sounds but senses it, it is often found in microphones and
speakers. As part of the piezo, two of the elements of the crystal are used to sense
vibration; the other is used to make vibration(s).
Within the helicopter design, when it is rotating, one sensor will maintain a stronger
signal than the other. When the helicopter is not rotating the two piezo elements make
contact with the vibration traveling through the crystal. This design is efficient and
consumes less power because there are no moving parts, or spinning motors. Today we
have the piezo gyro, in which there are two types of helicopter gyros available, the
heading hold (HH) and the yaw rate (YR).
The heading gyro uses computer software to detect the unwanted motion, correct it, and
then return the nose to its original position. This gyro continues to send commands to the
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tail rotor even after the motion stops. The heading gyro uses specialized software to
calculate the number of degrees the yaw or heading changes on the helicopter. The tail
rotor then receives this calculation as a direct command that it has been converted into.
The calculation in the form of a command appropriately corrects the amount of deviation
the heading of the helicopter was experiencing, it also dampens the movement.
With the heading hold gyro the helicopter is essentially locked, and its nose is unable to
change course no matter the outside movement. The helicopter will not change direction
until the rotor receives a new command to do so. By using the heading gyro, the tail rotor
servo is completely controlled by the HH gyro and its software.
The rate gyro functions a bit differently from the heading hold gyro. It works to dampen
the effects of any unwanted movement towards the yaw axis, not offer continual
correction. Once the unwanted movement has been detected, the rate gyro corrects it, and
then it stops correcting. For example SmartCopter is hovering and a gust of wind hits it
from the side. The rate gyro will stay the helicopter from thrusting its nose into the wind.
Eventually however the nose will drift into the wind. So the yaw rate gyro will not
prevent SmartCopter from turning but it will dampen the turning to a reasonable control
level.
There are two disadvantages to using the rate gyro. One is that unlike the heading hold
gyro the rate gyro does not return the helicopter to its original position. The second
disadvantage is that the corrective action is always late, because the motion is corrected
after it‟s been detected. The advantage of course is that unlike the heading hold gyro the
rate gyro does not completely take over the tail rotor servo.
Some of the disadvantages of using the heading hold gyro are that there are a lot of
demands placed upon the helicopter system as a whole. It requires a fast tail rotor servo,
and a much powerful battery to supply the servo. This route not only strains the servo, but
also consumes more power.
These requirements will need to be supported by a higher capacity battery because the
servos and gyros will need to be accounted for as well. Working with the heading hold
gyro will be a challenge because SmartCopter needs to be as light as possible. However
with the heading hold gyro a larger battery may be necessary to compensate for the
increase in power supply.
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These pictures are property of Sparkfun.com. They are photos of the gyro breakout board
that will be used with SmartCopter.
Gyro Breakout Board - IDG500 Dual 500 degree/sec - Property of SparkFun.com
4.2.1.2.4 Ultrasonic Range Finder
The ultrasonic range finder is a device used to measure distances between moving and/or
stationary objects. They operate without making contact with the measured surface. They
are useful in security systems and as possible infrared replacements. The ultrasonic range
finder contains a ping sensor. This ping sensor is responsible for measuring the distance
using sonar. By transmitting an ultrasonic pulse from the unit, the distance is determined
by measuring the time taken for the echo to return to the sensor. The ultrasonic pulse is
beyond human hearing capability.
The output that comes from the ping sensor is known as a variable-width pulse that
corresponds to the target‟s distance. How the device works is by using a pin to trigger the
ping sensor and then it listens for the echo‟s responding pulse. The distance to the target
can be effortlessly calculated by measuring this echo pulse.
The ultrasonic range finder will be useful to SmartCopter because the aircraft will need to
know its distance from the ground and any moving or non moving object at all times.
Without this device SmartCopter may not be able to function as a completely
autonomous aircraft without the user monitoring i‟s flight sequence to determine what
obstacles are in its path. By using the ultrasonic range finder SmartCopter is completely
dependent upon its own built-in components. The figure below is the sensor that will be
used with SmartCopter.
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Ultrasonic Range Finder – Maxbotix LV-EZ2 – Property of Sparkfun.com
4.2.1.3 Noise Filtering
Noise control is any passive or active means of minimizing sound emissions. Before
work is begun to reduce the noise, the source must first be located. Once the source of the
undesired sound has been located then the focus is to reduce the noise using engineering
applications. Noise reduction is the process of removing unnecessary noise from a signal.
There are different types of filtering devices.
In electronic devices a hissing noise is the undesired noise. The hissing is caused by
random electrons that have strayed from their path, due to heat influence. The voltage of
the output signal is influenced by these drifting electrons, and thus these electrons are
responsible for creating detectable noise.
Within SmartCopter noise will exist between the interfaces. We will need to use filters
such as the low-pass, high-pass, and band pass filters to recover the purest, original
signal. If not there will be a lot of mixed signals which will interfere with the
corresponding data. SCMs, signal conditioning modules, are used to measure process
control variables such as pressure, position, level, speed, temperature, and strain.
These control variables are constantly subjected to exterior induced noise signals. In
industrial measurement it‟s inevitable to avoid these noise sources which are formed of
electro-magnetically induced voltages or currents. The majority of noise voltages are
directly induced as the result of altering magnetic fields such as weather caused electrical
storms, and electric motor variable speeds.
Special shielded wires, appropriate grounding techniques, exist to help reduce induced
noise levels. In many cases however these techniques do not effectively reduce these
undesired noise signals. Noise signals embedded with signal detection modules are quite
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effectively used to minimize noise signals. There are three common filters that can be
used as the foundation for noise reduction: the low-pass filter, the high-pass filter, and the
band-pass filter.
The low-pass filter that accepts low-frequency signals and attenuates the higher
frequency signals above the cutoff frequency. The concept behind the low-pass filter
evident in different forms, some of which include digital algorithms for smoothing data
sets, blurring imagery, and electronic circuits.
With acoustic structure, the low-pass filter functions as a filter for transmitting sound and
is presented in the form of a physical barrier that tends to reflect higher frequencies.
Within the electronic structure, the low-pass filter is used to drive subwoofer (special
loud speaker) and other types of loud speakers, to block the high pitches that can‟t be
officially be broadcasted. Low-pass filters are also used in radio transmitter to block
harmonic emissions which can cause interference with other communications.
SmartCopter will certainly need a well balanced noise filtering system, to avoid any
major interference issues. The noise factors will almost always be present but if they can
be minimized to a low, SmartCopter can function at its best. Ideally the desire is to
eliminate all noise interference. The figure below represents the graph of an ideal low-
pass filter property of Wikipedia.
Ideal Low-pass Filter
For discrete-time realization, according to Kirchoff‟s Laws and the definition of
capacitance, the equations for a low-pass filter:
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where Qc(t) is the charge stored in the capacitor at time t. Substituting Equation (Q) into
Equation (I) gives , which can be substituted into Equation (V) so
that:
The high-pass filter is the opposite of the low-pass filter. It passes high frequencies well
and attenuates the lower frequencies below the cutoff frequency. They are also used in
audio applications. The simple first-order electronic high-pass filter is implemented by
placing an input voltage across the series combination of a resistor and a capacitor using
the voltage across the resistor as an output. For a passive high-pass filter the cutoff
frequency is equivalent to:
Where fc is in Hertz, τ is in seconds, R is in Ohms, and C is in Farads.
The figures above are property of Wikipedia.com
For an electronic implementation of a first-order high-pass filter an operational amplifier
is used in the figure below. The corner frequency is:
Active High-pass Filter
Discrete-time high-pass filters can also be designed. Discrete-time systems are described
in terms of difference equations. It refers to non-continuous time. According to
Kirchoff‟s Laws and the definition of capacitance the equations are:
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Where Qc(t) is the charge stored in the capacitor at time t. Substituting Equation (Q) into
Equation (I) and then Equation (I) into Equation (V) gives:
The band-pass filter uses both the low-pass and high-pass filters to pass frequencies
within a specific range and rejects the frequencies outside that range. An ideal band-pass
filter would consist of a flat pass-band and would attenuate completely all frequencies
outside the pass-band. No band-pass filter is ideal in practice.
The filter is unable to attenuate all outside frequencies. There is a region known as the
filter roll-off region located outside the pass-band area where frequencies are attenuated,
but not rejected. Band-pass filters have other uses outside of engineering applications
such as in atmospheric sciences. The figure below is property of Wikipedia.
Band-pass Filter
The physical applications of these filters have yet to be tested within SmartCopter, but
the aircraft will encounter some noise feedback, and these filters provide an introductory
solution to attenuating that unwanted noise.
4.2.1.4 Global Positioning System (GPS)
Before May 1 2000 civilian GPS‟ accuracy was purposely worsened by errors introduced
by a feature called Selective Availability in an effort, by the military, to prevent guided
weapons being created by the enemy. These errors could cause readings to be as far off as
100 meters and were on the average 10-20 meters off. However on that date president
Bill Clinton, with the support of other agencies, removed Selective Availability.[1]
Turning off the error for civilian GPS and in turn creating the ability for more accurate
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readings. Readings are now possible down to within 5 meters in accuracy for even
common civilian GPS devices, which is well within our requirements.
The GPS we will be using for our project is the EM-406A GPS shown in Figure 4.x
module from USGloabalSat. The EM-406A is based off the SiRF Star III chipset and has
an accuracy of 5 meters and time accuracy of 1microsecond. It is powered by 5 volts DC
at 44mA. The initialization time is dependent on whether or not initial location is given,
called a hot or cold start. The time for cold start initialization is 42 seconds on average
and the time for hot start initialization is 1 second on average. Reacquisition time is on
average 0.1 seconds. The output format for the GPS is a formatted string broadcast via
TTL over RS232. The output string format varies depending on the mode the GPS is in,
which can be identified by the protocol header at the beginning of the string. The GPS
unit updates its position every 1 second.
20 Channel EM-406A SiRF III Receiver with Antenna – Property of Sparkfun.com
Page | 35
[15]
Figure 4.2.2
Position of the GPS device is crucial to its function as it requires line of site in order to
get a good signal. However this poses some design problems on a platform such as our
helicopter. It needs to be mounted on the top of the helicopter to get good signal but at 16
grams this poses problems with shifting our center of gravity too high and hurting the
stability of our helicopter. To try to minimize this effect the receiver will be placed on top
of the fuselage just aft of the main rotor, as far forward as it can be. From there it‟s as
easy as connecting the TX and RX lines to the microprocessor and reading in the value in
software when it‟s needed. It will then be up to the microprocessor to parse the string and
come up with its numerical position.
4.2.1.5 Micro-Controller
To bring all of our hardware together we have our micro-controller. To be specific the
PIC18F4610,the 40 pin PDIP package shown in Figure 4.1.3.4.1, is the chip we will be
using for our project. With an internal clock of 48MHz it comes with a performance of
12MIPS providing plenty of processing power for our stability needs. On board the chip
has 64k of program memory and 2k of data memory, along with a 256 byte EEPROM.
Efficiency is improved with a limited instruction set of only 75 instructions with 8 more
extended instructions. Also provided are 13 analog to digital channels providing 10-bit
precision, which will be used to read our accelerometer and gyroscope data. The chip also
supports full USB 2.0 with a maximum transfer speed of 480Mb/s.
Page | 36
[10]
Figure 4.1.3.4.1
Our chip also features various power modes and clock scaling abilities. While for a
majority of our project our CPU will be in the RUN mode it's important to at least
acknowledge the other modes. For example the CPU is capable of an IDLE mode where
periferals all remain on while the CPU is off and a SLEEP mode where the peripherals
and CPU are off. The sleep mode is the standard legacy sleep mode offer in all PIC
devices and is enabled by clearing the IDLEN bit and executing the SLEEP instruction.
This will bring the currently selected clock to a stop until an interrupt is detected.
Alternatively the IDLE mode can be selected by setting the IDLEN bit to '1' and again
executing the SLEEP instruction. However this time the peripherals will remain clocked
while the CPU isn't and will remain in IDLE mode until an interrupt occurs. However for
our project we need the CPU to remain in the running, for that reason these modes may or
may not be implemented.
Another important feature of our CPU is it's clock selection and scaling abilities. Our
chip features support for two external clocks up to 48MHz along with eight different
internal clock modes ranging from 8Mhz to 31kHz. This gives us a total of 12 different
clock modes. The first four, HS, HSPLL, XT and XTPLL, modes are for when a crystal
resonator is connected to the pins OSC1 and OSC2. An internal postscaler allows the user
to scale this frequency by 1/2, 1/3, or 1/4 of the original frequency. There is also a PLL
module for frequency multiplication that will be discussed a little later. For our project
we will likely have a 20MHz resonator crystal connected externally to pins OSC1 and
Page | 37
OSC2 shown in the diagram in Figure 4.1.3.4.3. C1 and C2 will be set at 15pF based off
specifications in the PIC18F4610 data sheet.
[10]
Figure 4.1.3.4.3
The next four modes are for support of external clock sources and are, EC, ECIO,
ECPLL, ECPIO. The IO modes provide input and output on the RA6 pin. The PLL
modes are used as a frequency multiplier and is designed to produce a 96MHz clock from
a 4MHz source. The block diagram showing the PLL frequency multiplier is shown in
Figure x.x. This rounds our external clock sources.
[10]
Figure 4.1.3.4.4
Page | 38
The final four modes, INTHS, INTXT, INTCKO, and INTIO, we have are the internal
clocking modes which can be used to drive two separate clocks. These modes all use the
internal clock for the micro-controller and depending on which of the four modes a
seperate clock is used as the clock for the USB. In the INTHS mode the USB clock is
provided by the oscillator in HS mode. Likewise in the INTXT mode the USB clock is
provided by the oscillator in XT mode. The other two are for when a external clock is
supplied the difference between the two being that INTCKO sets the OSC2 pin as Fosc/4
while INTIO sets the OSC2 pin as regular digital IO pin. More than likely the preferred
mode we'll be using will be the INTHS mode such that we can use the 20MHz external
resonator shown earlier to drive our USB module and our internal clock for our micro-
controller.
One of the most import features of our micro-controller for our project is the 10-bit
analog to digital converter module. The chip we selected has support for up to 13
channels of A/D conversion. The module has five important registers, the A/D Result
High Register (ADRESH), A/D Result Low Register (ADRESL), A/D Control Register 0
(ADCON0), A/D Control Register 1 (ADCON1), and the A/D Control Register 2
(ADCON2). A table showing the register layouts and what the values correspond to is
shown below in Figure x.x.
ADCON0
--- --- CHS3 CHS2 CHS1 CHS0 GO/ DONE ADON
Bit 7 Bit 0
CHS3:CHS0: Analog Channel Select bits
GO/ DONE : A/D Conversion Status bit
0 = A/D idle
1 = A/D in progress
ADON: A/D Enable bit
ADCON1
--- --- VCFG0 VCFG0 PCFG3 PCFG2 PCFG1 PCFG0
Bit 7 Bit 0
VCFG0 (bit 5): Voltage Reference Configuration bit Low
0 = VSS
1 = VREF- (AN2)
VCFG0 (bit 4): Voltage Reference Configuration bit Low
0 = VDD
1 = VREF+ (AN3)
PCFG3:PCFG0: A/D Port Configuration Control Bits
Sets number of analog channels to use.
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1111 = No digital Channels
1110 = 1 Analog Channel
…
0010 = 12 Analog Channels
ADCON2
--- --- ACQT2 ACQT1 ACQT0 ADCS2 ADCS1 ADCS0
Bit 7 Bit 0
ACQT2:ACQT0: A/D Acquisition time select
111 = 20 TAD 011 = 6 TAD
110 = 16 TAD 010 = 4 TAD
101 = 12 TAD 001 = 2 TAD
100 = 8 TAD 000 = 0 TAD
ADCS2:ACQT0: A/D Conversion clock select bits
111 = FRC 011 = FRC
110 = FOSC/64 010 = FOSC/32
101 = FOSC/16 001 = FOSC/8
100 = FOSC/4 000 = FOSC/2
The basic idea behind using the A/D module is first initialize the converter, setting the
registers ADCON2:ADCON0, and then turning on the converter with the ADON bit.
Next step would be to configure the A/D interrupt so it goes to our ISR when the
conversion is done. Then if you the capacitor CHOLD isn‟t charged you have to wait a
given acquisition time which is typically in the 2.5 microsecond range. Once these
requirements are met you can begin conversion by setting the GO/ DONE bit and then
wait for the interrupt. Once the interrupt hits read the values in the ADRESULT registers
and reset the interrupt.
The GPS module will be controlled via a simple RS232 interface using a formatted
string.
One of the major advantages of the chip we selected is that it comes ready out of the box
to be used with USB. It does this with an onboard Serial Interface Engine or SIE
complete with its own 1k of RAM dedicated to USB. While the micro-controller does
have access to all sections of the RAM, sections being used by the SIE should not be
accessed. The block diagram showing each of the USB peripheral‟s components is shown
below in Figure 4.1.3.4.9.
Like the various other modules talked about earlier in this section the USB has multiple
control registers that are used to initialize the device. Along with the control registers is a
status register much like the one provided on the analog to digital convert. The
transceiver for the USB peripheral is built-in and support regular USB and USB 2.0 full-
speed transfers. The module has support for use with an off-chip transceiver however for
our project we will likely just make use of the internal transceiver.
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[10]
Figure 4.1.3.4.9
Now that the various chip peripherals are defined we can address the issue of the memory
layout on our micro-controller. The diagram below in Figure 4.1.3.4.10 shows the general
layout of the micro-controller‟s memory. Program instructions are stored on the on-chip
flash memory. Memory is addressed in bytes and instructions are stored as two bytes or
four bytes depending on the type of instruction. The instruction set is comprised as 70
instructions with 15 more extended instructions. The device is programmed over an ICSP
connection which is shown in Figure 4.1.3.4.11. The other memory used is 256 bytes of
EEPROM non-volatile storage for holding any data such as constants that may be needed.
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[10]
Figure 4.1.3.4.10
The schematic showing the planned connections on our printed circuit board are shown
below in Figure 4.1.3.4.11. There is also a button and an LED not shown, the LED is on
pin PORTA 0 and the button is on PORTE 2. The schematic also shows how the analog
modules and SD card will be hooked up to the micro-controller. The PIC in the schematic
is still labeled as being a PIC18F4550 but it should be noted that it is in actually a
PIC18F4610.
Page | 42
Figure 4.1.3.4.11
4.2.2 Software
The software for our project will be split into two sections. The first section we'll focus
on is the embedded software that will be going for a flight with our helicopter, later on
we'll discuss base station software used to analyze data once the flight has concluded.
The embedded software will be laid out in a hierarchy shown below in figure x.x. At the
bottom of the hierarchy are the sensor modules for each individual interface. The first of
which is the analog digital convert module which allows for analog signals to be read
from the accelerometers, gyros, and digital range finder. The values will be read
sequentially and then stored into an array of sensor data that can then be accessed by
higher functions in the hierarchy. It is also worth noting that the analog digital convert
module does not store any information other than the last read value from each sensor. It
is up to the general sensor module to keep track of past values to find rate of change,
which we will go into more in depth later.
Page | 43
The next sensor module to discuss is the GPS module. This module is similar in that no
calculations are done here, only the last value read from the GPS is stored so it that can
be retrieved by the modules higher on the hierarchy. However this module differs in the
way that the data is read. Instead of using the analog digital convert, the data is read
through a serial interface that retrieves a formatted string from the GPS unit. This string
is then parsed such that the positioning data is extracted and then saved so that it may be
retrieved later. The only data saved from the parsed string will be the latitudinal position
and the longitudinal position.
It will be the job of the general sensor module to keep track of previous values and track
the change of these variables over time. For example with the data obtained by GPS, by
tracking the previous location compared to the current location we can deduce an
estimation of the speed of our craft. The other example of the general sensor module's
responsibility is tracking the past measurements from the gyro and accelerometer. By
integrating these values over time, for example from the accelerometer we can track a
rough estimation of the motion, which we can then use to check the values from our GPS
sensor module. Integrating again with respect to time yields a rough estimation of the
position of the craft. The extent of this will be just limited to simple error checking,
further integration and analysis will be designed in the base station software. It is also the
job of the general sensor module to relay the sensor information to the higher levels of
the hierarchy. Unlike other modules the GPS has no initialization required due to the fact
that once the GPS unit has power it immediately starts outputting its position. The GPS
string parsing will be done depending on what type of output the device is set for.
Initially however no string parsing will be done and the direct data from the GPS is sent
Page | 44
to the SD Card. For example purposes I‟ll go over the most important output formatting
which is the GGA format. All strings output by the GPS start with a header indicating the
protocol of the message and each data field is separated by commas. For GGG the header
line will be „$GPGGA‟. A sample input string and table showing the stored values are
shown below in Figure 4.1.4.3.
[11]
Figure 4.1.4.3
Finally the last lower level module to design is the module in charge of writing to the SD
card. This is done through an SPI interface using existing library AN1045 available on
the Microchip website. Using a FAT32 file-system every time the SmartCopter is
initialized a new file is created on the SD card with the current date and start time as the
filename. It will then write all data received to the file writer module and put it in that file
until the end of the flight. It will store the current time of the flight in a time stamp at the
beginning of every data recording. This will be then followed by the location in latitude
and longitude followed by the altitude. Following this will be the accelerometer and gyro
data, initially just raw data from the sensors will be stored however later on adjustments
could be made such that some processing of the data could be done before it is stored and
included as with the raw data.
Controlling everything is the top level module controller. It‟s job is to initialize each
component and synchronize each event. At the start of every flight it will initialize the
sensor module and the file writer module, creating a new file every time a flight is
Page | 45
initialized. It will then be the controller‟s responsibility to have the sensor module update
each sensor and then pass that information to the file writer to all it to update the file.
Once the flight is complete the controller will then close the file writer and stop updating
the sensors. It will then wait until another flight is requested where it will return to the
beginning and start the process over.
The next piece of software in our project will be the software running on the base station
that‟s task is to read back the data stored in the flight and represent it a meaningful
graphical way. To accomplish this we will store the data streamed wirelessly to a hard
drive via a TV Tuner card and recording software. This video will then be synced up with
the data that was stored on the SD card. To accomplish this we will use the Java Media
Frame work to embed the video into a Java GUI along with various measurements of
data. A rough example of this GUI is shown in the figure below
GUI Sample
The code for the base station will also be laid out in a hierarchy with a main controller at
the top making sure everything is initialized and synced up. On the next level there will
be a video controller responsible for getting the correct image onto the GUI based on
what time in the flight currently marked. Also on this level is data manager that handles
the data being read off the SD card. The data manager is passed a time from the controller
and using that time will return a series of measurements from each device from the file on
the SD card. Finally at the very bottom of the hierarchy is the video encoder which
handles the raw video data such that it can be displayed onto the GUI and there is also a
raw file manager that handles reading from the SD card and passing that information onto
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the data manager. An overview of the hierarchy for the base station software is shown in
the figure below.
Hierarchy overview for the Base Station Software
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Chapter 5: Testing Procedures
5.1 Helicopter Flight
Since maintaining stable flight is going to be a major aspect for project SmartCopter,
many tests will need to be done to ensure the project will occur without fail. Due to the
potential financial burden that a failed mission would incur, learning the flight
characteristics and flight controls of the helicopter is an absolute necessity. In order to
ensure the structural integrity of the helicopter, certain test procedures need to be
implemented. To start off with, team SmartCopter needs to become familiar with manual
flight controls of the helicopter. To accomplish this, the whole team will learn how to
manually fly the helicopter via a computer flight simulator. The flight simulator allows
the user to virtually fly and control the helicopter without physically flying it. This is a
must for any person who has never operated a radio controlled helicopter. Fortunately
the helicopter the team will be purchasing includes a flight simulator for that particular
model helicopter. The flight simulator will aid the team in learning the extremely
complicated controls for a helicopter. The simulator will teach the team how to utilize
the different components of flight, such as pitch, roll, and yaw, to maintain stable flight.
Figure 5.1.1 displays the typical flight controls:
[17]
Figure 5.1.1
Typical helicopter flight controls
Page | 48
The flight simulator that will be utilized for learning the necessary flight controls is the
ClearView RC Flight Simulator®. The program comes preloaded with a variety of exact
model rc helicopters to choose from. However the simulator also allows for specific
model radio controlled helicopters to be loaded into the program for more accurate and
realistic results. Another reason the ClearView RC Flight Simulator® was chosen was
due to its various landscape and weather choices. The ability to control the helicopter in
varying weather and climate conditions will contribute to better piloting skills of the
team. Since the team will not be able to predict what the weather conditions will be like
on the presentation day, they will need to feel confident they can successfully pilot the
helicopter in less than ideal conditions. This particular simulator also supports multiple
controller options. These include keyboard input, PlayStation 3® controls, and the rc
transmitter via usb input. Since helicopter flight is complicated and difficult to master,
the team will begin by learning on the PlayStation 3®
controller. This is due in part to the
familiarity of the team to the PlayStation 3® controller, and the complexity of the layout
of the transmitter controls. This will allow the team to learn the aspects of helicopter
flight first, without having to simultaneously learn the controls of the transmitter. The
team will then transition to the use of the actual transmitter purchased with the rc
helicopter model Esky Belt-CP 450.
After the team has successfully completed the necessary flight simulator controls, they
will learn to fly the helicopter manually. Manual controls are accomplished via the
included 6 channel transmitter (72 MHz, Mode 2) and receiver. The beginning stages of
this particular phase of testing will occur in the back yard of a single home property
located off of University Blvd referred to as testing location 2. A map and directions to
testing location 2 are outlined in Figure 5.12.2. This testing phase does not require a very
large area for testing, as the helicopter will be secured to a homemade testing stand. The
homemade test
stand will be
constructed
utilizing the
following
components:
36”L x 36”W x
2”D plywood
base, 36”L x 2”W
x 4”D lumbar, (4)
1/8” u-bolts and
nuts. The test
stand will function
as a mode of
securing the
helicopter to an
immobile
platform, while at
the same time still
allowing for
Page | 49
freedom of flight. The test stand will be constructed as depicted in Figure 5.1.2. Detailed
plans needed for fabrication of the stand are depicted in section 5.11.
The necessary holes will be drilled into the plywood stand base allowing for the insertion
of the u-bolts. Documentation relating to the construction of the test stand is outlined in
Figure 5.11.1. The helicopter will then be secured to the base by placing the landing
skids between the previously drilled holes. The u-bolts will then be fastened to the base
via the corresponding 1/8” nuts. The maximum distance of the eye of any u-bolt and the
top of the base shall not exceed 2”. This basically will limit the altitude the helicopter
will be able to achieve, while still allowing proper testing during the take-off and landing
procedures. Measurements need to be recorded during take-off and landing to test how
the shock of the impact affects the recorded data. The configuration of the test stand, as
depicted in Figure 5.1.2 with the u-bolts not completely securing the unit to the stand,
will be the only occurrence of this setup. However this will not be the last use of the
actual base of the stand. An additional setup will be utilized in later testing.
After the team feels confident that they can successfully take off and land the helicopter
properly via the test stand, the next phase of testing will begin. The single home property
located off of University Blvd referred to as testing location 2 will be once again utilized
during testing. This next phase still involves testing of the take off and landing
procedures. However the testing stand will be configured in a slightly different manor
which will allow for a greater altitude to be achieved. Holes for the u-bolts will be drilled
in the corners of the test stand base. The u-bolts will then be mounted to base, but this
time the helicopter
skids will not be
enclosed in the u-bolts.
Strong, but light
weight fishing wire
will be used to secure
the helicopter to the
test stand. Four
strands of 5‟-2”
fishing wire will be
needed. One end of a
length of the fishing
wire will be secured to
each u-bolt, while the
other end secured to
portions of the
helicopter skids.
Figure 5.1.3 shows the
configuration of the
stand and skids for this
stage of testing. Since
a serious crash of the
helicopter could
Page | 50
potentially jeopardize the successful completion of the project, testing in small
increments is an absolute necessity. Unlike the previous stage of testing which only
allowed the helicopter to achieve an altitude of 2” above the test stand, this stage allows
the helicopter to achieve an altitude of roughly 5‟.
The final stage for the testing of the manual flight controls of SmartCopter will occur
without the aid of the test stand. However certain precautions will still need to be
undertaken to ensure the structural integrity of the helicopter. A relatively large open
area, with a minimal amount of people is necessary for learning manual flight of the
helicopter. A large open field on the corner of University Blvd and Dean Road in
Orlando, Florida will be the location for testing of manual flight. A map and directions to
this testing location are outlined in Figure 5.12.1. The location offers adequate open area
for flight and at the same time is not heavily trafficked. The terrain is ideal for learning
manual flight due to its composition. The area is mostly grass and soft soil. This will be
beneficial in case any unfortunate crash of the helicopter occurs, due to the potential
forgiveness from the impact. This area will be referred to as testing location 1. Since
SmartCopter will not be secured to the test stand and therefore no altitude limitations, the
use of numerous blankets, sheets, and towels will be utilized. The team will square off an
area of approximately 15 feet x 15 feet, and systematically place all of the impact
absorbing materials, one on top of another, inside the squared off area. Testing of the
take off and landing procedures will take place in the center of the square. The use of the
sheets, blankets, and towels will help absorb any impact that may occur in the event of an
unexpected crash. Once manual flight is achieved by all team members, the team will
begin the process of incorporating the data recording system with the rc helicopter.
During the process of designing SmartCopter‟s flight data recording system, testing of
the system will need to occur regularly. This will aid in limiting the amount of code
and/or hardware that will need debugging or troubleshooting. Extensive testing will also
ensure the accuracy and reliability of the system as a whole. The team will test each
individual component separately, then fully integrated. Testing will begin with the
ultrasonic range finder, gyroscope, accelerometer, and GPS. Once complete, software
will be debugged, and testing will begin on the data writing to SD card interface. The
helicam and video streaming will get tested followed by a fully integrated system. It is
with extreme importance that project SmartCopter perform as expected on the day of
presentation. With rigorous amounts of testing required, additional batteries for the
helicopter, receiver, and helicam will need to be purchased. Additional testing
accommodations that will be necessary for testing are outlined in section 5.10. These
will increase the amount of time that the helicopter will be operable, creating more
productive test flight days.
5.2 Hardware Connections
In order to ensure the accuracy and functionality of the electrical components of
SmartCopter, all of the soldering connections shall be tested for solid connectivity. This
will be accomplished by utilizing the different capabilities of a 29 range digital
Page | 51
Multimeter purchased from RadioShack®. The main functions of the Multimeter that will
be needed for testing consist of the connectivity test function, DC voltage measurement,
and current measurement. The first component to be testing will be the source voltage
(Vdd) and ground connection. The circuit board shall have a source voltage of 5V DC.
The circuit board will receive its source voltage via a splice into the wiring for the
brushless motor. The motor receives its input voltage from the 11.1V Lithium Polymer
battery supplied with the helicopter. The motor purchased with the helicopter contains a
built in voltage regulator to step down the voltage from the supplied 11.1V to 5V. This is
accomplished by setting the Multimeter to measure DC voltage, and placing the positive
lead to the source voltage input of the circuit board, and the negative lead to the ground
input of the circuit board. A successful test shall yield a result of 5V. A source voltage
of 5V is required to power the microprocessor, ultrasonic range finder, and the SiRF Star
III global positioning system.
Not all of the
components of
SmartCopter need
an input voltage of
5V. A source
voltage of 3.3V will
be required to
power the
gyroscope,
accelerometer, and
the SD card
interface. Therefore
the next component
to be tested will be
the voltage
regulator that steps
down the source
voltage from 5V to
3.3V. The diagram
of the voltage
regulator to be
incorporated is depicted in Figure 5.2.1. This particular layout consisting of the various
capacitors and resistors was chosen due to its improved ripple rejection. The input
voltage tolerances of the electrical components is relatively small, therefore the layout
depicted in Figure 5.2.1 was the optimum choice.
Testing shall consist of the same technique involved in testing the source voltage of the
circuit board. The positive lead of the Multimeter will be placed on the input pin of the
LD 1117 adjustable voltage regulator, and the negative lead placed on the ground input of
the circuit board. A successful test shall yield a result of 5V. This indicates the voltage
regulator is receiving the proper input voltage of 5V. The next step will be to disconnect
the positive lead from the input of the voltage regulator and connecting it to the output
Page | 52
pin of the voltage regulator. A successful test shall yield a result of 3.3V. This indicates
the voltage regulator is functioning correctly and producing an output voltage of 3.3V.
Due to the multiple components requiring an input voltage of 3.3V, the output of the
voltage regulator will be soldered to its own supply bus bar. This will be the next area of
testing. The positive lead of the Multimeter will be disconnected from the output pin of
the voltage regulator and connected to the 3.3V bus bar. A successful test shall yield a
result of 3.3V. This confirms that any component connected to the 3.3V bus bar will be
accurately receiving an input voltage of 3.3V. After the source voltages of the circuit
board have been confirmed, the team will then transition into testing of the individual
electronic components.
5.3 Ultrasonic Range Finder
The first component to get tested will be the ultrasonic range finder. The first step to
ensure accurate readings is to visually inspect the soldering points. A loose or badly
soldered wire could result in false readings or malfunction. The ultrasonic range finder
selected for SmartCopter operates on a supply voltage of 5V. Measuring the input
voltage of the ultrasonic range finder consists of connecting the positive lead of the
Multimeter to the pin labeled “+5V” of the range finder, and the negative lead to the pin
labeled “GND” of the range finder.
A reading of 5V will confirm the
sensor is receiving the desired input
voltage. The next test to be
performed will be the continuity
check of the range finder. This is
accomplished by switching the
function dial of the Multimeter to the
continuity check, then connecting the
positive lead to the pin labeled “AN”
of the range finder and negative lead
to pin 3 of the microprocessor. The
Multimeter will buzz and display
“Shrt” if the circuit is shorted, or it
will not buzz and display “Open” if
the circuit is not shorted. The
desired readings are depicted in
Figure 5.3.1.
Next the physical component itself will be tested to confirm functionality and accuracy.
Different objects will be placed at varying predetermined distances and the output voltage
will be recorded. The analog output voltage will be measured from by placing the
positive lead of the Multimeter to the pin 3 of the microprocessor and the negative lead to
the ground bus of the circuit board. A scale factor of 9.766mV per inch is applied to the
analog output. Since the team will know the distances of the placed objects, they will be
able to calculate the expected output voltages prior to testing. The output voltage will
Page | 53
then be multiplied by 102.4 to obtain the distance in inches from the range finder to the
object. If any discrepancies in output voltage and/or distances measured are discovered,
the range finder will be removed then either reinstalled or replaced, depending on the
findings.
5.4 Gyroscope
The next component to get tested will be the gyroscope. To begin a visual inspection of
the soldering points will occur. Insufficient connections may cause the gyroscope to
malfunction, output false readings, or potentially not function completely. The gyroscope
selected for SmartCopter operates on a supply voltage of 3.3V. Measuring the input
voltage of the gyroscope consists of connecting the positive lead of the Multimeter to pin
9 labeled “VCC” of the IMU 5 Degrees of Freedom IDG500/ADXL335, and the negative
lead to pin 8 labeled “GND.” A reading of 3.3V will confirm the sensor is receiving the
desired input voltage. The next test to be performed will be the continuity check of
gyroscope‟s outputs. This is accomplished by switching the function dial of the
Multimeter to the continuity
check, then connecting the
positive lead to pin 7 of the
gyroscope labeled “XRATE”, and
the negative lead to pin 4 of the
microprocessor. The Multimeter
will buzz and display “Shrt” if the
circuit is shorted, or it will not
buzz and display “Open” if the
circuit is not shorted. The process
will be repeated by disconnecting
the positive lead of the Multimeter
and connecting it to pin 6 of the
gyroscope labeled “YRATE”, and
connecting the negative lead to pin
5 of the microprocessor. The
desired readings are depicted in
Figure 5.4.1.
5.5 Accelerometer
The next component that will need to be tested is the accelerometer. The first step to
complete is to visually inspect the soldering points. Loose connections could potentially
result in false readings or possible malfunction of the accelerometer. The accelerometer
selected for SmartCopter operates on a supply voltage of 3.3V. Measuring the input
voltage of the accelerometer consists of connecting the positive lead of the Multimeter to
pin 9 labeled “VCC” of the IMU 5 Degrees of Freedom IDG500/ADXL335, and the
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negative lead to pin 8 labeled “GND.” A reading of 3.3V will confirm the sensor is
receiving the desired input voltage. The next test to be performed will be the continuity
check of accelerometer‟s outputs. This is accomplished by switching the function dial of
the Multimeter to the continuity check, then connecting the positive lead to pin 3 of the
accelerometer labeled “ZOUT” and the negative lead to pin 7 of the microprocessor. The
Multimeter will buzz and display “Shrt” if the circuit is shorted, or it will not buzz and
display “Open” if the circuit is not
shorted. The process will be
repeated by disconnecting the
positive lead of the Multimeter,
and connecting it to pin 2 of the
accelerometer labeled “YOUT”.
The negative lead of the
Multimeter will be connected to
pin 8 of the microprocessor. The
process will once be repeated by
disconnecting the positive lead of
the Multimeter, and connecting it
to pin 1 of the accelerometer
labeled “XOUT”. The negative lead
of the Multimeter will be
connected to pin 9 of the
microprocessor. The desired
measurements are depicted in
Figure 5.5.1.
5.6 SiRF Star III Chipset
The SiRF Star III Chipset will be the next component to get tested. Once again testing
will begin by visually inspecting all associated soldering points for solid connections.
The SiRF Star III chipset selected for
SmartCopter operates on a supply
voltage of 5V. Measuring the input
voltage of the SiRF Star III chipset
consists of connecting the positive lead
of the Multimeter to the pin 2 of the
chipset labeled “VIN” of the SiRF Star
III chipset, and the negative lead to pins
1 and 5 of the chipset labeled “GND”.
A reading of 5V will confirm the GPS
unit is receiving the desired input
voltage. The next test to be performed
will be the continuity check of the SiRF
Star III chipset. This is accomplished by
switching the function dial of the
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Multimeter to the continuity check, then connecting the positive lead to pin 3 of the
chipset labeled “RX”, and the negative lead to pin 26 of the microprocessor. The
Multimeter will buzz and display “Shrt” if the circuit is shorted, or it will not buzz and
display “Open” if the circuit is not shorted. The process will be repeated by
disconnecting the positive lead of the Multimeter and connecting it to pin 4 of the chipset
labeled “TX”, and connecting the negative lead to pin 25 of the microprocessor. The
desired readings are depicted in Figure 5.6.1.
Additional testing of the functionality and proper will occur as well. To test the accuracy
of the SiRF Star III GPS unit, various predetermined locations will be utilized to compare
SmartCopter‟s global positioning readings with other sources of global positioning. To
begin with, the team will use Google® maps to acquire the latitude and longitude of
certain previously selected locations. The team members will then drive to these
locations and utilize another device to measure latitude and longitude coordinates. The
team will now obtain the GPS coordinates through the use of Research in Motion‟s®,
Blackberry Bold® global positioning abilities. Once at the desired destination, the
coordinates will be acquired via this method. After these coordinates are recorded, the
SiRF Star III unit will be tested. The team will record the readings from the SiRF Star III
unit. Once all location coordinates have been recorded, the team will compare all of the
results to determine the accuracy of SmartCopter‟s GPS feature. A successful test will
yield results within 200m between all the recorded locations.
5.7 HeliCam
After testing of the SiRF Star III chipset has commenced, the team with then test the
function of the 2.4GHz wireless HeliCam. The camera operates on a 9V battery, and
transmits the video wirelessly to a supplied transmitter. Testing of the helicam with be
quite simple. The 9V battery will be connected to the camera, and the transmitter will be
connected to a television through the use of an RCA cable. If the camera operates with
minimal intereference, it will be incorporated into the base station computer. The base
station computer will have a video tuner card installed to allow for an RF cable
connection. The helicam with then be connected to a Super NES® RCA to RF video
converter. The Super NES® RF will get connected to the RF connector of the video tuner
card installed in the base station computer. A successful test will record the video
streaming from the camera to memory on the base station.
5.8 SD Card Interface
The last component that will need to be tested is the SD card interface. The first step to
complete is to visually inspect the soldering points. This particular component has the
most connections that must be inspected. Since the data needs to be accurately recorded,
loose or inadequate connections must be redone. The SD card interface selected for
SmartCopter operates on a supply voltage of 3.3V. Measuring the input voltage of the
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SD card interface consists of
connecting the positive lead of the
Multimeter to pin 1 of the SD card
breakout board labeled “CS and the
negative lead to pin 5 labeled
“GND.” A reading of 3.3V will
confirm the pin is receiving the
desired input voltage. This same test
will then be performed on pins 2, 3,
4, 6, and 7 labeled, “DI”, “VCC”,
“CLK”, “DO”, “IRQ”, and “P9”
respectively. A desired reading of
3.3V will yield a successful test. This
will confirm that the SD card
breakout board is receiving proper
input voltage for operation. The
desired results for the input voltage at
the desired pins of the SD card
breakout board are displayed in
Figure 5.8.1.
The next test to be performed will be the continuity check of SD card breakout board
outputs. This is accomplished by switching the function dial of the Multimeter to the
continuity check, then connecting the positive lead to pin 1 of the SD card breakout board
labeled “CS” and the negative lead to pin 35 of the microprocessor. The Multimeter will
buzz and display
“Shrt” if the
circuit is shorted,
or it will not buzz
and display
“Open” if the
circuit is not
shorted. The
process will be
repeated by
disconnecting the
positive lead of the
Multimeter, and
connecting it to
pin 2 of the SD
card breakout
board labeled
“DI”. The
negative lead of
the Multimeter
will be connected
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to pin 37 of the microprocessor. This test will be performed from pin 4 of the SD card
breakout board labeled “CLK” to pin 34 of the microprocessor. Then it will be perform
from pin 6 of the SD card breakout board labeled “DO” to pin 33 of the microprocessor.
Next it will be perform from pin 9 of the SD card breakout board labeled “CO” to pin 39
of the microprocessor. Finally the last continuity test will be performed from pin 10 of
the SD card breakout board to pin 40 of the microprocessor. The desired results are
depicted in Figure 5.8.2.
Once all of the connections have been tested for adequate input voltage and proper
connectivity, the team will begin testing of writing the data to the SD card. The first data
entry that will be written to the SD card will be the data output from the ultrasonic range
finder. Since previous measurements were taken for the range finder, the team will know
if the data written to the SD card was done so correctly. If the recorded data is the same
as was expected, the team will know that writing to the SD card is occurring. This will
ensure that all of the connections correct and that the associated software functioning. At
this point it is not necessary that the software for writing all of the other data to the SD
card is entirely correct. This at least shows the team that they are on the right track in
terms of software and hardware.
After the initial data has been written to the SD card, data from the SiRF Star III chipset
will get written to the SD card. The data will be compared to the previously measured
global positioning coordinates. A successful test will yield the same latitude and
longitude coordinates as was recorded from the known GPS locations. From this point,
similar tests will be done for the accelerometer and gyroscope. Initial tests for the
accelerometer and gyroscope readings will be done via a “hand flown” method.
Essentially the team will perform the tests without the platform of the helicopter. One
team member will simulate the helicopter flight characteristics by moving the circuit
board through the air. The SD card will be removed and the results will be obtained. A
successful test will record all of the desired results from the various components of
SmartCopter.
5.9 Fully Integrated System
Once manual flight testing and the various electrical component testing have been
complete, testing of the data recording system has a whole will occur. This stage of
testing is just as critical as the previous stage. Just as before, testing will occur in
incremental steps. This will allow for a narrower scope to troubleshoot in case an error
does take place. Initial testing for data recording system of SmartCopter will take place
at the previously selected area on the corner of University Blvd and Dean Road, referred
to as testing location 1. This location provides ample space with minimal interference.
The area is also in close relation to the homes of two of team SmartCopter‟s members as
well as the University of Central Florida. This will prove beneficial for the transportation
of all the necessary equipment, and in the event where redesign must occur. Testing of
the fully incorporated system will only commence after the team is fully confident they
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can manually fly the helicopter, and after all of the individual components have been
tested.
In order to properly test the accuracy of the data recording system the team will need to
test each aspect of the
controls one step at a
time. This is crucial
in troubleshooting any
problem that may
arise during testing.
Due to the potential
financial impact and
loss of completed
work, the team must
take every
precautionary tactic
possible to avoid any
type of crash. The
team must also take
care not to physically
lose SmartCopter.
This could be a
possibility in the event
the unit strays off
course. If the team
were to lose visibility
and not be able to recover the unit, this could be ended up causing a failure of the project.
At this point in time, the team has put forth a relentless and time consuming effort, and
failure is not an option. For this phase of testing, the team will once again utilize the test
stand as configured in Figure 5.9.1.
The location for this test will again take place at testing location 1. A map and directions
are shown in Figure 5.12.2. After all the necessary setup is complete, testing of the fully
integrated SmartCopter system will begin. Testing for the fully integrated system will be
similar to testing of the manual flight controls of the helicopter. Due to the additional
weight and different balancing points, the team will need to familiarize themselves with
the altered flight characteristics of the helicopter. Manual flight will occur with the
fishing line tethered to test stand, and the helicopter attached to the line as similar to
previous testing. Each team member will take turns learning and observing how different
the helicopter‟s flight is altered. After the new flight characteristics are studied, and
adjustments made, SmartCopter will be ready to commence its final test. This will be a
test of the entire SmartCopter system without the aid of any test stand or tethering. Since
SmartCopter will not be secured to the test stand and therefore no altitude limitations, the
use of numerous blankets, sheets, and towels will once again be utilized. The team will
square off an area of approximately 15 feet x 15 feet, and systematically place all of the
impact absorbing materials, one on top of another, inside the squared off area. Testing of
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the fully incorporated system will take place in the center of the square. The use of the
sheets, blankets, and towels will help absorb any impact that may occur in the event of an
unexpected crash. The team will manually fly SmartCopter, while SmartCopter‟s data
recording system records the data to the SD card, and wirelessly transmits the video of
the flight. A successful test will include proper and accurate writing of all the necessary
components to the SD card while simultaneously transmitting a video feed wirelessly to
the base station.
5.10 Testing Accommodations
In order to maximize the productivity and efficiency of all testing days, certain
accommodations must be addressed. These issues include the acquisition of necessary
testing supplies as well as non-essential supplies. Once acquired the transportation and
storage of all project related materials will need to be coordinated. The first process that
needs to occur for testing is acquiring all of the supplies and materials needed for testing.
The items needed to construct the test stand as well as a carrying case, which will be
described later in this section, will be purchased from the local Home Depot store. This
includes all the necessary lumbar and hardware. The stand will be constructed by team
member Brian Williams with the aid of a family member. The location for the
fabrication of the stand and carrying case, along with the use of all the required tools that
are needed for construction, will be supplied by the aforementioned family member. This
will incur no additional cost to the project.
Along with the materials for the stand and case, various tools will be needed throughout
the duration of the project. These tools will be on loan to the team by project member
Brian Williams. In the event that additional tools are required, the attempt to obtain the
tools via resources that will not increase the cost of the project will be made. If the tools
cannot be gathered, the sponsorship funding will cover the cost to purchase them. All of
the blankets, sheets, and towels that will be utilized for testing will be donated to the team
via the team members themselves. Along with the necessary items required for testing,
some non-essential items will need to be acquired as well. Non-essential test items
include items that are not needed for testing, but will ultimately increase the overall
efficiency on test days. Some of these items include an additional battery for the
helicopter and extra batteries for operation of the transceiver during manual flight testing.
This will allow the team to have a longer run time of the helicopter. Proper
accommodations such as electricity, computer availability, and close proximity to a
covered facility will also prove viable resources during testing. Close proximity to
shelter will benefit the team in the event of a sudden change of the weather conditions.
After all of the materials and supplies have been acquired, the issues of storage and
transportation become a concern. Storage of all the testing stand and tools will be the
responsibility of team member Brian Williams. Since initial testing of the integrated data
recording system of SmartCopter will take place at the house of a relative of Brian
Williams, the testing materials will be stored at that location. Storing the supplies and
materials for the project will ultimately expedite the testing procedures as transportation
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of the materials will not need to occur. Testing at this facility is available at any given
time to project SmartCopter.
The last issue to be addressed is that of the transportation of all the needed materials,
tools, equipment, and SmartCopter itself. Due to the sensitive nature of the helicopter,
and the need for as few setbacks as possible, the helicopter needs to be protected during
all times during transportation and storage. A carrying case previously addressed will be
constructed for use during transportation. The design of the carrying case is depicted in
Figure 5.10.1.
[2]
Figure 5.10.1
SmartCopter carrying case
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The case will be made of some of the same materials used for the test stand. These
include sheets of 2” plywood, hinges, screws, u-bolts, and nuts. The fabrication of the
carrying case will be completed by team member Brian Williams. The design of the case
is a simple design that secures the helicopter in place, while at the same time protecting it
from outside forces. It relies on 4 hinges fastened to the base and the two long sides.
This permits two sides to fold down allowing for easy placement of the helicopter inside.
The helicopter will be secured to the base in a similar fashion to the testing stand.
However during storage and transportation, the u-bolts will be completely tightened to
the skids of the helicopter. This is depicted in an enlarged view of the carrying case base
shown if Figure 5.10.2.
This will prevent any movement inside of the case. The two shorter sides will be
securely fastened to the base of the carrying case as they will not be on hinges. The top
of the case will then be placed on top of the assembled portion and tightly secured with
the use of eight hand tightening wood screws. Transportation of SmartCopter along with
all of the necessary supplies and tools will mainly be the responsibility of team member
Brian Williams. This team member has a vehicle that contains ample storage for the safe
transport of SmartCopter and all project related materials.
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5.11 Detailed Plans
The following plan depicted in Figure 5.11.1 is for the construction of the test stand.
[2]
Figure 5.11.1 Test stand
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The following plan depicted in Figure 5.11.2 is for the construction of the carrying case.
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5.12 TESTING LOCATIONS
The following map shown in Figure 5.12.1 is referring to testing location 1. The location
was chosen due to its adequate open area for flight and at the same time is not heavily
trafficked. The terrain is ideal for learning manual flight due to its composition. The
area is mostly grass and soft soil. This will be beneficial in case any unfortunate crash of
the helicopter occurs, due to the potential forgiveness from the impact.
[2]
Figure 5.12.1 Map of testing location 1 on the corner
of University Blvd and Dean Road
DIRECTIONS:
From the University of Central Florida, head west on University Blvd.
At Dean Road intersection head north on Dean Road.
Testing location is located on west side of Dean Road.
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The following map shown in Figure 5.12.2 is referring to testing location 2. The location
was chosen due to the relationship to team member Brian Williams. The location is in
close relation to the University of Central Florida as well as Brian‟s home as well as the
home of Matthew Campbell.
[2]
Figure 5.12.2 Map of testing location 2
off University Blvd
DIRECTIONS:
From the University of Central Florida, head west on University Blvd.
At Suncrest Blvd intersection head south on Suncrest Blvd.
Head east on Cherry Oak Circle, then north
End at physical address 10529 Cherry Oak Circle
Location is on west side of Cherry Oak Circle
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The following map shown in Figure 5.12.3 is referring to an alternate testing location in
case the other two locations are unavailable during the time needed. The location was
chosen due to its adequate open area for flight and at the same time is not heavily
trafficked. The terrain is similar to that of testing location 1.
[2]
Figure 5.12.3 Map of possible testing location 3
DIRECTIONS:
From the University of Central Florida, head west on University Blvd.
At the intersection of University Blvd and Goldenrod Road head south on
Goldenrod Road.
Location is on east side of Goldenrod Road.
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Chapter 6: Mounting Hardware
To accommodate for all of the necessary electrical components that SmartCopter shall
contain a necessary mounting plate to house all of the hardware. The following
depictions in Figure 6.1.1 and Figure 6.1.2 show the layout of the proposed mounting
hardware. Due to size limitations and constraints, a custom mounting plate will need to
be fabricated. The dimensions of the skid plate are unique to the model of helicopter
purchased; therefore no enclosures that are in production that have the required area
needed.
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Chapter 7: Future Project Upgrade Possibilities
7.1 Potential Uses
One of the purposes for project SmartCopter is to eventually integrate SmartCopter‟s data
recording system into an autonomous piloting system. The team will be able to utilize
the data recorded to provide the necessary software in order to achieve this feature. Now
visualize a world where an aircraft is able to change the way we retrieve information in
our daily life. Whether it is military based, traffic inspection or life or death
circumstances, the SmartCopter is what is needed to manage the situation with ease. This
lightweight, GPS regulated aircraft is designed to travel to a pre-programmed GPS point
with the purpose of taking still images at that time and location.
When it comes to military tactics, taking precaution is a must in the safety of our troops.
With the SmartCopter at hand our troops are able to find new ways to take on a mission
without the dangers of taking unnecessary risks. With the ability to take pictures from an
inconspicuous view, through camps or over the swampy terrain, the military will have
advantages that have never been available before.
Dealing with conditions that involve crowds of people has a higher risk of ending in
madness and disarray. When it comes to big events, festivities or even protests, it is a
huge advantage to get a bird‟s eye view of the conditions at that event. With the
SmartCopter, these situations can be controlled and managed to prevent chaos and
possible injury through its ability to photograph the crowd settings of the programmed
GPS location. Returning with these snap shots of the crowd range, crowd shift or maybe
even criminal acts being achieved will give the outsiders an upper hand in maintaining
peace in these testy situations.
In the occurrence of a package or unidentified object is under suspicion of foul play, the
standard routine is to send a workforce in to investigate the situation at hand. However,
with the SmartCopter, this is no longer a risky operation. Say that a call comes in for a
suspicious package, the area is cleared of all civilians, and the risk is too high to send in
staff. Simply send off the SmartCopter to investigate through pictures either close up or
from a distance and return to unharmed personnel to take action accordingly. With no
individuals harmed, and now information on the package, it is easy to see why this device
is essential in risky situations.
A life or death situation is the most crucial of all. A lot of times our law enforcement are
required to operate risky tasks in order to save a life in a rescue mission. With the
SmartCopter, rescue procedures have never been so safe and premeditated. Over high
cliffs, mucky waters or dangerous areas of our earth, the SmartCopter is able to get a
clear view of what is going on around it in order for our people to make a safe planned
route of rescue.
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With life or death in mind, another trivial threat is fires. Raging flames, whether from a
house or in nature, create major damage and are one of the most dangerous natural
disasters to be contained. Say a house is on fire and the situation is being evaluated, the
SmartCopter can easily act as a third eye for assessment.
Whether inside the house collecting pictures of the fire sources or hovering above to seek
the areas of crucial concern, the device is playing a part in the rescue through the heavy
smoke and flames. In addition to the SmartCopter assisting during a fire, it is also capable
of aiding in the aftermath of a fire.
The debris after a fire is put out can be dangerous in more ways than one. The heavy ash
all around and remaining smoke is a hazard to workers searching the ruins. But with the
knowledge of the overall remnants before venturing onto the scene, injury may be
prevented and game plans can be assessed.
Aside from disastrous conditions, the SmartCopter is also beneficial for relaying
information on a concern that we battle everyday, traffic. The every morning and
afternoon fight to beat or avoid traffic can be averted with the helpful knowledge of
alternate routes, or even specific areas to steer clear of at that exact moment. If this
everyday nuisance can be prevented in anyway, the SmartCopter‟s job is achieved.
7.2 Multi-Helicopter Coordination
With the apparent limitless potential uses of project SmartCopter, and the great impact
that a single unit could have on human life, it would only seem logical that multiple
SmartCopters working in coordination with one another would be able to have an even
greater impact on the quality of life. The range and potential life saving abilities of a
team of SmartCopters would be extraordinary. There are many different situations in
which a group of SmartCopters would be more beneficial than a single SmartCopter.
With the ever increasing threat of natural and manmade disasters, precautions need to be
undertaken to ensure that minimal amount of human exposure to these situations occur.
One example of this would be the extremely dangerous threat of wildfires. A wildfire
can spread over a vast area of forest, and can be extremely hard to handle.
One of the problems fire fighters have to deal with when fighting large wildfires, is
knowing the extent of the size of the fire. A team of SmartCopters would be capable of
surveying the disaster area without risking any human exposure to the actual fire or
smoke.
Another possible use for a team of SmartCopters would be in the event of another
terrorist attack. The horrific attacks that took place on September 11, 2001 on the Twin
Towers in New York City, opened up everybody‟s eyes to the realization that ultimately
nobody is safe. The United States government has taken the best precautions possible to
ensure this does not happen again. However there is always a chance.
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In the unfortunate event, that another attack occurs on the United States, a team of
SmartCopters would be able to survey damage almost immediately. This would greatly
increase the survival rate of such an attack. One of the major hurdles the rescuers faced
was their ability to locate remaining survivors. The amount of debris that was released as
a result of the falling of the Twin Towers was unimaginable. This severely limited the
mobility and capabilities of the search teams. A team of SmartCopters would be able to
survey the attack site, and relay vital information to the rescue team way before they
even stepped foot on the site. With the incorporation of infrared sensors, SmartCopter
would even have the capability of locating survivors trapped under a pile of fallen rubble.
With the incorporation of multiple SmartCopters into a single team, many obstacles
would need to be overcome to avoid any potential collisions. The major one would be
communication amongst all the individual units. Each unit would need to have the ability
to relay vital information about their position and altitude.
The biggest problem with that is the ability to communicate instantly. With all
communications there is a slight delay from the time a signal is sent, to the time it is
received. The amount of delay is a direct correlation with the type of technology used.
Back in the days of the Space Race and the first landing on the moon, this was obviously
apparent. Due to the great distance between the Earth and the moon, it would take a little
extra time for a radio wave to reach the moon and back.
The great distance between the earth and the moon caused a slight delay in
communication between Houston and the astronauts. As time passed along and
technology progressed, solutions to these delays were found. The solution to this is what
is known as Real Time Communication. Real Time Communication is communication
where information can be transmitted and received instantly or with seemingly negligible
delay.
Chapter 8: Timeline
The objective for the first semester consisted of establishing a group, and working
together to complete the appropriate documentation. Our time was spent conducting
research, meetings, and building our design. The table consists of completed tasks and
meetings for each week during the first semester.
The second semester consisted of building and testing the SmartCopter, reviewing design
statistics, completing it and presenting it. The goal was to have it completed by
Thanksgiving break.
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Month
Objective
May
Choose project design idea, Commence
project research
June
Continue research, find sponsors, research
work divided amongst group members
July
Research parts and compare, present SD1
presentation
August
Modify design criteria
September
Order parts, commence software
development, begin copter stabilization
and learn copter operations using flight
simulation, begin testing hardware
components
October
Modify design, begin programming
microcontroller, commence GPS
Guidance System (hardware & software),
hardware
November
Complete hardware system, implement
software, establish test sight, test flight
operations (time permitted), combine
hardware and software components
December
Final week and final presentation,
complete project, fix encountered errors
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Chapter 9: Budget
9.1 Parts List
This chapter contains a tentative list of the parts SmartCopter will need, and it provides
descriptions for each, as well as photos which have been provided by Sparkfun.com.
Part Price per
Unit ($)
Quantity Total
($)
Esky Belt-CP 450 RC Helicopter 200.00 1 200.00
PIC 40 Pin 48MHz 16K 13 Channel A/D USB-
18F4610
11.39 1 11.39
Ultrasonic Range Finder – Maxbotix LV – EZ2 27.95 1 27.95
Triple Axis Accelerometer Breakout – ADXL 330 34.95 1 34.95
Gyro Breakout Board – Dual 500 degree/sec 59.95 1 59.95
20 Channel EM – 406A SiRF III Receiver with
Antenna
59.95 1 59.95
2.4Ghz HeliCam 39.95 1 39.95
I. Esky Belt-CP 450 RC Helicopter
This helicopter has a 6-channel brushless radio. It contains a belt-driven tail rotor
vibration free, and offers smoother tail control. It‟s perfect for indoor or outdoor use. It‟s
capable of flying backward, skyway, and 3D aerobic.
Length: 650mm (26 inch)
Height: 230mm (9 inch)
Flying Weight: 670g (24 oz)
II. PIC 40 Pin 48MHz 16K 13 Channel A/D USB – 18F4610
The PIC Micrcontroller uses a full speed USB 2.0 interface. It‟s perfect for low power
outage. The 18F4610:
16k of flash
12 MIPs (Microprocessor without Interlocked Pipeline Stages)
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III. The Ultrasonic Range Finder – Maxbotix LV-EZ2
It offers an admirable size and decent quality. It can control up to 10 sensors with just 2
pins. Specs:
42kHz Ultrasonic sensor
Operates from 2.5-5.5V
Low 2mA supply current
20Hz reading rate
RS232 Serial Output – 9600bps
Analog Output – 10mV/inch
PWM Output – 147uS/inch
Small, light weight
VI. Compass Module – HMC6352
A simple breakout board for the popular HMC6352, it provides a ready to use electronic
compass that combines 2-axis magneto-resistive sensors, analog and digital support
circuits, and heading computation algorithms.
Simple I2C interface
2.7 to 5.2V supply range
1 to 20hz selectable update rate
True drop-in solution
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0.5 degree heading resolution
1 degree repeatability
Supply current: 1mA@3V
V. Triple Axis Accelerometer Breakout – ADXL330
This breakout board from Analog Devices provides a low noise and power consumption
experience.
Dimensions: 0.7 x .7”
VI. Gyro Breakout Board – Dual 500 degree/sec
The IDG-300 has a smaller profile than some single axis gyros, it‟s also cost efficient. It
offers high temperature and humidity resistance.
Integrated X- and Y-axis gyro on a single chip
Low offset voltage
Integrated low-pass filters
Integrated reset switches for high-pass filters
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Superior vibration rejection over a wide frequency range
High cross-axis isolation by design
3V single supply operation
5000 g shock tolerance
RoHS Compliant (Completely Lead free)
VII. 20 Channel EM-406A SiRF III Receiver with Antenna
This module includes on-board voltage regulation, LED status indicator, and a built-in
patch antenna.
Weight: 16g including cable
20-Channel Receiver
Extremely high sensitivity: -159dbm
Smallest complete module available: 30mm x 30mm x 10.5mm
Outputs NMEA 0183 and SiRF binary protocol
70mA at 4.5-6.5V
Cold Start: 42s
Warm Start: 38s
Hot Start: 1s
10m Positional Accuracy/5m with WAAS
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VIII. 2.4GHz HeliCcam
A micro wireless video camera
Camera and transmitter weight: 9 grams
Camera and transmitter size: 15mm x 22mm x 32mm ((5/8" x 7/8"
x 1 1/4")
Camera Lux: < 3 @ f1.2
Camera Auto Electronic Exposure of 1/60 to 1/15000 sec. w/Auto
Gain & White Balance
Camera Signal to Noise Ratio: > 48dB
365K (PAL) or 250K(NTSC) camera pixel resolution
Wireless Transmission Range: 150M (450 Feet), Line-of-sight
Transmitter RF Output Power: EC R & TTE Compliant
Receiver Video Input/Output: 1Vp-p/75 ohm
IX. IMU 5 Degrees of Freedom
This PCB board incorporates the IDG300 dual-axis gyroscope and Analog Devices
Dimensions: 0.75” x 0.9” (20 x 23mm)
Weight: 2g
9.2 Funding
Funding will be provided by Nelson Engineering Co. of Merritt Island, Florida and
Rogers, LoveLock, and Fritz Architecture. The budget presented at the beginning of this
section is the basis of what SmartCopter will require. Additional parts not included may
be purchased as well. Both benefactors will sponsor equal amounts of funding. The
present purchasing plan consists of purchasing the parts individually and receiving
reimbursement at the appropriate time.
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Chapter 10: Conclusion
The team behind the project SmartCopter utilized knowledge gained from various
disciplines in the fields of Computer Science and Electrical Engineering to complete their
design. SmartCopter will be a device that records flight data such as acceleration,
rotation, current heading and current video while being mounted beneath a RC helicopter.
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Chapter 11: Appendix
References:
[1] Anderson, John D. (2004), Introduction to Flight (5th ed.), McGraw-Hill, pp. 257–
261, ISBN 0-07-282569-3
[2] Padfield, Gareth D. (2007), Helicopter Flight Dynamics (2nd
ed), Wiley-Blackwell,
pg. 92 ISBN 978-1-4051-1817-0
[3] Heffley, R. K. & Mnich, M. A. (1988), Minimum-Complexity Helicopter Simulation
Math Model, NASA.
[4] Bak, T. [2002], Modeling of Mechanical Systems,
http://www.control.auc.dk/~jan/undervisning/MechanicsI/mechbook.pdf
[5] Wie, B. [1998], Space Vehicle Dynamics and Control, AIAA Educational Series. 110
[6] Hald, Ulrik B. , Autonomous Helicopter Modeling and Control, Aalborg University
[7] Leishman, Gordon J. (2002), Principles of Helicopter Aerodynamics, Cambridge
University Press
[8] Johnson, Wayne. Helicopter Theory, Dover Publications
[9] http://www.xheli.com/wa4chdr53cor.html
[10] http://ww1.microchip.com/downloads/en/DeviceDoc/39632D.pdf
[11] http://www.sparkfun.com/datasheets/GPS/NMEA%20Reference%20Manual1.pdf
[12] http://www.sparkfun.com/datasheets/Components/HMC6352.pdf
[13] Nguyen, Hung T. Fuzzy Modeling and Control, CRC Press
[14] http://www.ngs.noaa.gov/FGCS/info/sans_SA/docs/statement.html
[15] http://www.sparkfun.com/datasheets/GPS/EM-406A_User_Manual.PDF
[16] Courtesy of Brian Williams via Autodesk program Revit MEP 2009
[17] Courtesy of Brian Williams via Autodesk program Revit MEP 2009, and open
source google images
[18] “military aircraft.” Encyclopaedia Britannica. 2009. Encyclopaedia Britannica
Online. 09 Aug. 2009 http://britannica.com/EBchecked/topic/382295/military-aircraft
[19] http://www.dragonflyx6.com.html
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Bibliography
1) http://heli.stanford.edu/papers/AbbeelCoatesHunterNg_aaoarch_iser2008.pdf
2) http://www.cs.cmu.edu/afs/cs/project/chopper/www/goals.html
3) http://www.draganfly.com/uav-helicopter/draganflyer-x6/applications/
4) http://www.grandhobby.com/exrcre4503d6.html
5) http://electronics.howstuffworks.com/brushless-motor.htm
6) http://www.omega.com/prodinfo/accelerometers.html
7) http://www.rctoys.com/
8) http://www.rchelicopter.com/
9) http://www.slickzero.com/
10) http://www.acroname.com/robotics/info/articles/devantech/srf.html
11) http://www.parallax.com/dl/docs/prod/acc/PingDocs.pdf
12) http://www.hobbyengineering.com/H2951.html
13) http://www.sparkfun.com/
14) http://www.xheli.com/
15) http://www.servocity.com/html/hitec_servos.html
16) http://www.epanorama.net/documents/motor/rcservos.html
17) http://en.wikipedia.org/wiki/Main_Page
18) http://www.seattlerobotics.org/guide/servos.html
19) http://www.rchelicoptertips.com/rc-heli-beginners/rc-heli-gyro/
20) http://www.rchelicopterfun.com/rc-helicopter-gyro.html
21) http://www.heliproz.com/jwgyros.html
22) http://www.electric-rc-helicopter.com/article/gyroconfusion.php
23) http://www.dimensionengineering.com/accelerometers.htm
24) http://www.magneticsensors.com/gpssolutions.html
25) http://www.proxdynamics.com/images/uploads/Proxflyer-UVS-04.pdf
26) http://www.gpsreview.net/electronic-compass/
---------- Forwarded message ----------
From: Boe AnnDrea <[email protected]> Date: Tue, Jul 28, 2009 at 4:55 PM
Subject: Re: Permission to use Pictures
To: Allie Rolle <[email protected]>
Hello Alvilda Rolle!
Yes you may use our photos for your senior project. Thank you for asking, and good luck with
Page | 81
your project.
Best,
AnnDrea Boe
__
Director of Marketing Communications SparkFun Electronics
6175 Longbow Drive, Suite 200 Boulder, CO 80301
On Jul 28, 2009, at 2:08 PM, Allie Rolle wrote:
To Whom It May Concern
My name is Alvilda Rolle. My group and I are currently working on a senior design project through the University of Central Florida. I would like to obtain your permission to use photos
from your website please. Thank you for your reponse concerning this matter. Sincerely,
A. Rolle
--
~Allie~
HighLevelController: /*Store series of waypoints as a linked list*/ struct waypoint { struct GPS_position* target; int lingerTime; float lingerHeading; struct waypoint* nextWaypoint; }; struct GPS_position* myPosition; struct waypoint* currentWaypoint; //Calculates desired heading float calcHeading(struct GPS_position* current,struct GPS_position* target); /*Converts string read by USBController to GPS cooridnates*/ struct waypoint* parseWaypointFile(char* str); int main() { GPSController:intiGPS
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char* str = USBController:readFile currentWaypoint = parseWaypointFile LowLVLFlightController.setMode(TAKE_OFF) while(currentWaypoint != NULL) { LowLVLFlightController.setHeading(calcHeading(...)) LowLVLFlightController.setMode(TRAVEL_TO) while(GPSController:comparePosition(from,to) != 0) { LowLVLFlightController.step(); GPSController:updateGPS myPos = GPSController:getPosition } LowLVL.setHeading(lingerHeading) LowLVL.setMode(HOVER) while(lingerTime < timer) { LowLVL.step() timer++ } currentWaypoint = currentWaypoint->nextWaypoint } LowLVL.setMode(LAND) return 0; } LowLevelController: #define TAKE_OFF 0 #define HOVER 1 #define TRAVEL_TO 2 #define LAND 3 int currentMode; float x; float y; float z; float dx; float dy; float dz; float ddx; float ddy; float ddz; float theta; float omega; float psi; float thetadot; float omegadot; float psidot;
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float thetadotdot; float omegadotdot; float psidotdot; void setHeading(float heading); void setMode(int mode); void step() { switch mode: case 0: takeoff() break; case 1: hover() break; case 2: travelto() break; case 3: land() break; } //Takes control until mode is finshed. void takeoff() void land() //Samples sensors each iteration and corrects as necessary void hover() void travelto() USBController: //starts usb device void init() //stops usb device void destroy() //reads waypointfile char* readFile(char* fname); ServoController: float u_col; float u_long; float u_lat; float u_tail; void setUCol(float ucol); void setULong(float ulong); void setULat(float ulat); void setUTail(float utail); float getUCol(); float getULong(); float getULat();
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float getUTail(); void output(int direction); MotorController: float myRPM; void setRPM(float rpm) float getRPM() GPSController: struct GPS_position { float latitude; float longitude; float altitude; }; struct GPS_position* currentPosition; void updateGPS(); struct GPS_position* getPosition(); char* getGPSOutput(); void parseGPSString(char* str,float* lat,float* longi,float* alt); //Compares two GPS points and returns the range between the two int comparePosition(struct GPS_position* p1,struct GPS_position* p2); CompassController: float myHeading; init() updateHeading() float getHeading()