Main Project - FINAL COPY 786

A Project report
on
DESIGN AND FABRICATION OF QUADCOPTER
Submitted in partial fulfillment of the requirement for the award of degree of
BACHELOR OF TECHNOLOGY
in
Mechanical Engineering
Submitted By
ROHIT SAI RAJ. S
LAXMI SAI SHANKAR. C
10D41A03C0
10D41A0398

Under the Guidance of
Dr. P. Mallesham
Principal
B.E., M.E., Ph.D., ISTE(LM)., AMIE (India), IWS, IFS, CSI
Department of Mechanical Engineering
SRI INDU COLLEGE OF ENGINEERING AND TECHNOLOGY
(Affiliated to Jawaharlal Nehru Technological University)
2014

Accredited by NBA
CERTIFICATE
This is to certify that the project work entitled “DESIGN AND
FABRICATION OF QUADCOPTER” is the bonafide work done by,
ROHIT SAI RAJ. S 10D41A03C0
LAXMI SAI SHANKAR. C 10D41A0398
The students of Department of Mechanical Engineering in SRI INDU COLLEGE OF
ENGINEERING & TECHNOLOGY submitted this project to JNTU, Hyderabad in
partial fulfillment of the requirements for the award of B.Tech degree in Mechanical
Engineering. This work has been carried out under my guidance and has not been
submitted the same for any university/institution for the award of any degree/diploma.
Internal Examiner HOD
Principal External Examiner

DECLARATION
We hereby declare that the entire work embodied in this project entitled
“DESIGN AND FABRICATION OF A QUADCOPTER” has been carried out
by us.
No part of it has been submitted for the award of any Degree or Diploma at any
other University or Institution.
S. ROHIT SAI RAJ (10D41A03C0)
C. LAXMI SAI SHANKAR(10D41A0398)

ACKNOWLEDGEMENT
I have taken efforts in this project. However, it would not have been
possible without the kind support and help of many individuals and organizations.
I would like to extend my sincere thanks to all of them.
My deep thanks to the Principal, Dr. P. Mallesham, the Guide of the
project, for guiding and correcting various documents of mine with attention and
care. He has taken pain to go through the project and make necessary correction
when needed.
I express my thanks to the Head of Department, M. Srinivas Rao,
Mechanical Engineering of Sri Indu College of Engineering and Technology, for
extending his support.
I would also thank my Institution and my faculty members and technicians
without whom this project would have been a distant reality.
Finally, I take this opportunity to extend my deep appreciation to my family
and friends, for all that they meant to me during the crucial times of the
completion of my project.

ABSTRACT
An unmanned aerial vehicle (UAV) is an aircraft capable of flying without a pilot
or crew on-board. UAV's can be piloted remotely via a remote-control (RC), though
controlling the aircraft autonomously or semi-autonomously is constantly noted. This can
be achieved through a pre-programmed flight. Military applications benefited, still
benefiting, the most since UAV's come in different sizes and shapes, but UAV's can also
be used in other variety of applications such as aerial photography, scientific exploration,
and small-sized items transportation.
Potential applications of autonomous vehicles range from unmanned surveillance to
search and rescue applications dangerous to human beings. Vehicles specifically designed for
hover flight have their own possible applications, including the formation of high gain airborne
phased antenna arrays. With this specific application in mind, our team sought to produce a
four rotor hovering vehicle (Quadcopter) capable of eventual untethered acrobatic autonomous
flights. The modelling is done in PRO-E wildfire 5.0 software and the mechanical design of the
AFV included both the selection of a battery-motor-prop combination for efficient thrust
production and the design of a lightweight yet sufficiently stiff vehicle structure. The
components chosen were selected from the variety of brushless motors, battery technologies
and cell configurations, and fixed pitch propellers suited to use in a four rotor hovering vehicle.
The vehicle structure settled upon achieved a high degree of stiffness with minimal weight
through the use of thin walled aluminum compression members supported by stranded steel
cable.
While a hardware failure prevented the completion of a full range of tests, the team was
able to complete a hands-free hover test that demonstrated the capabilities of the vehicle.
Supplemented with various other final hardware tests, the vehicle demonstrated stable hover
flight, potential vehicle endurance in the range of 6-8 minutes, and possible vertical acceleration
beyond the hover thrust. The final vehicle represented a significant achievement in terms of
overall design and vehicle capability while future improvements will demonstrate more
advanced nonlinear control algorithms and acrobatic flight maneuvers.
[6]

TABLE OF CONTENTS
CHAPTER PAGE NO
1. INTRODUCTION 1
2. LITERATURE REVIEW OF UAV QUADCOPTER 6
2.1 Quad rotor 6
2.2 Background 7
3. MODELLING IN Pro-E WILDFIRE 5.0 12
3.1 About Pro-E 12
3.2 Modeling components individually 12
3.2.1 Rod 12
3.2.2 Plate 15
3.2.3 Motor 15
3.2.4 Propeller 16
3.3 Sub Assembly 16
3.4 Final assembly 17
4. HARDWARE CHARACTERISTICS & SOFTWARE DESIGN 19
4.1 Block Diagram 19
4.2 Mechanical Components Characteristics 20
4.2.1 Frame Characteristics 20
4.2.2 Propellers Characteristics 22
4.3 Electrical & Electronic Characteristics 22
4.3.1 Actuator Characteristics 23
4.3.1.1 Motors Characteristics 23
4.3.1.2 Electronic Speed Controller (ESC) 24
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CHAPTER PAGE NO
7. OPERATION AND CONTROL THEROY 45
7.1 Forces acting on quadcopter 41
7.2 Quadcopter operation 46
7.3 PID control 48
7.3.1 PID controller 48
7.4 Inertial measurements 49
7.5 Control inputs 49
[8]
CHAPTER PAGE NO
4.3.2 Sensors Characteristics 25
4.3.2.1 Gyroscopes Characteristics 25
4.3.2.2 Accelerometer Characteristics 25
4.3.3 Transmitter & Receiver Characteristics 26
4.3.4 Microcontroller Unit (MCU) Characteristics 26
4.3.5 Battery Characteristics 28
4.4 Software & Control Design 29
5. SELECTED COMPONENTS SPECIFICATIONS 30
5.1 Selected Mechanical Components. 30
5.1.1 Selected Frame 30
5.1.2 Selected Propellers 31
5.2 Selected Electrical & Electronic Component 31
5.2.1 Selected Actuators 31
5.2.1.1 Selected Motors 31
5.2.1.2 Selected Electronic Speed Controller 32
5.2.3 Selected Transmitter 33
5.2.4 Selected Receiver 33
5.2.5 Selected Microcontroller Unit (MCU) 34
5.2.6 Selected Battery 35
6. MECHANICAL DESIGN 37
6.1 Quadcopter Modeling 37
6.2 System dynamics 37
6.3 Kinematic Equations and Euler’s angles 41
6.4 Motor alignment 43
6.2 Propeller balancing 43
6.5 Total balancing 44

7.5.1 Roll control 50
7.5.2 Pitch control 51
7.5.3 Yaw control 52
8. IMPLEMENTATION & RESULTS 53
8.1 Assembly 53
8.2 Software and control algorithm 54
8.3 Flight Testing & Results 54
8.3.1 Preflight testing 54
8.3.2 Flight attempts 55
8.4 Future and work development 56
9. CONLUSION 56
10. BIBLOGRAPHY 58
LIST OF FIGURSS PAGE NO
1. Schematic diagram of a Quadcopter 6
2. Tyes of motions 7
3. Breguet- Richet gyroplane 8
4. Oehmichen Quadcopter 9
5. Dragonfler x4 10
6. Hexakopter 11
7. Starting pro-E 13
[9]

8. Selection of planes 13
9. Sketch and extrude 14
10. Plate 15
11. Motor 15
12. Propeller 16
13. Nut 16
14. Assembly of rod and plate 17
15. Assembly of motor and propeller 17
16. Final assembly 18
17. Block diagram of a Quadcopter 19
18. Brushless DC motors 24
19. Micro control unit 26
20. Software and control design 29
21. Frame set used 30
22. Pair of selected SF 1045 propellers 31
23. ESCs (Electronic speed controller) picked 32
24. Fly Sky FS-CT 6B Transmitter (6 channel) 33
25. Fly Sky Receiver FS-R 6B 33
[10]

26. Multiwii SE V2.0 34
27. NED & ABC Reference Frames 38
28. Forces Acting on a Quadcopter 45
29. Yaw,Pitch,Roll 47
30. Illustration of Various Moments of a quadcopter 47
31. Controls in accordance with the transmitter 50
32. Roll Control 51
33. Pitch Control 51
34. Yaw Control 52
[11]

CHAPTER-1
INTRODUCTION
1.1 Overview
The popularity of UAV Quadcopter has been only among military applications till
1996. However, with the development of complex and capable electronics ranging from
more powerful, light-weight microcontrollers to even smaller sensors with better
accuracy and precision, it's possible to build Quadcopter with variety of sizes for
different applications.
Quadcopter particularly have been getting quite a lot of attention lately due to
several reasons. One of these reasons is the fact that a Quadcopter is relatively easy
to build and assemble, having less mechanical complexities than other aircraft such as
helicopters, in most cases no gearing between the rotor and the motor is required.
Another reason is the fact that the design of a Quadcopter is depending on four propellers
instead of one big rotor, which is great due to the less kinetic energy generated, and so in
a case of crash the damage would be less catastrophic and easier to fix and maintain. Also
the relative small size of a Quadcopter, which could also be big in several applications,
makes it suitable for surveillance and other tasks where small size is critical. The ability
to control and hover a Quadcopter in low-speeds and its outstanding maneuverability
makes it perform in an excellent manner in aerial photography, scientific exploration, and
small-sized items transportation. Search & Rescue in places that are dangerous or
unreachable for humans, Quadcopter can do the job in searching and stream live images
of the scene.
[12]

The most difficult part about a Quadcopter isn't lying in the building phase, but in
the software/programming phase. The success of a Quadcopter depends mainly on how
good the control algorithm is, the control loop should be able to compensate any errors
during flight with the help of the sensory feedback. The compensation of error shouldn't
be too aggressive, at the same time not painfully slow. It's crucial to reach the balance
between these two, and reaching this state of balance isn't simple nor trivial by any
means. Every millisecond in execution process counts and could be the deciding factor.
Integrating a control theory (approach) in the code is essential to reach this state, with the
Proportional-Integral-Derivative (PID) being most commonly used in such projects.
Since the Quadcopter depends on analog sensors to act as the “eyes”, it's vital to have
precise and accurate feedback from the gyroscope and the accelerometer. In most cases
where analog sensors are integrated, the readings of such sensors are filled with noise.
With Quadcopter in particular, it's quite important not to have “blurry eyes”, and so the
noise must be filtered. Implementing a filter in the algorithm to accomplish such a job is
also quite tricky. Despite the fact that Kalman filter is popular in such projects, another
type has been integrated in the code, that is a complementary filter. This filter is suitable
for the Quadcopter being not processor (microcontroller-wise) intensive and with the
least amount of lag, which is also crucial in stability projects.
1.2 Scope
In the Hashemite Kingdom of Jordan, where natural resources are scarce,
accomplishing the Quadcopter Project with the title Search & Rescue as its main theme is
quite promising and unique. Deserts dominating a large scale of the whole country, in
addition to distant villages and territories inhabited by citizens are all motivating reasons
to have such a project. In a case of emergency, the Quadcopter could be a great, fast, and
economical solution, in which it would be sent to sweep the desired area and provide live
and valid information about the situation. The Quadcopter could also provide emergency
kits and drugs to those camping in the desert or exploring distant areas, when time is
virtue and instant actions are needed. Having the Quadcopter as the "eyes in the sky" is
[13]

the driving element in this project. Having mobile senses that could save others and
eliminate certain dangers can be faster, safer and more efficient than moving a rescue
crew themselves, and that is the utmost desire.
Furthermore, the uniqueness of the Quadcopter to its core provide an interesting
material subject for scientific publications and researches. It's also an initiative to do
similar kind of projects for fellow students and enthusiasts
1.3 Applications
Areas where Quadcopter can be utilized and also their potential applications are
summarized as follows:
• Search & Rescue: In places that are dangerous or unreachable for normal humans,
Quadcopter can do the job in searching and showing live images of the scene. With the
addition of a GPS geotagging and navigation, exceptional results are expected.
• Commercial use: without the need to rent a helicopter for thousands of dollars, aerial
photos and videos can be taken for many different needs; from cinematic, media and
news coverage to photographing professionals and hobbyists whom like to capture great
photos and videos from high altitudes.
• Transporting objects: A Quadcopter can easily transport small objects, which makes it
a great tool for wide variety of needs, for example; transporting medical supplies in
places where sudden catastrophes occur and rapid medical support is needed.
• Educational use: for a project to build or upgrade one, great amount of knowledge and
benefits can be gained and the eager need to make it fly with great stability makes this
[14]

project one of the most exciting ways to learn and understand the true meaning of
engineering and how an engineer should think.
• RC hobbyists: it is considered one of the most amazing toys to be flown and enjoyed,
with its great maneuverability and high speed. In countries like Germany and USA
people are spending a lot of money to experience flying Quadcopter.
• About any sensor can be added to it: which makes the areas for it to be used simply
diverse and variant; like adding a temperature sensor or gas sensor makes it a very
efficient, fast and safe method for taking different measurements in places like chemical
or nuclear reactors, where dangerous materials can be found and them being unsafe for
humans to stay for long periods.
1.4 Current Aims & Objectives
With the given time frame and some other limitations, it has been an important step to
declare the base goals and aims in this project. These targets are summarized as
following:
• Building a light-weight, yet sturdy Quadcopter that could take crashes with less
damage with the help of custom-made protective edges and suitable landing gears.
• Building the base of a project that is surely to be upgraded and developed in all
aspects.
• Achieving a stable flight in the present time.
1.5 Outline
The upcoming chapters is going to provide further details about the Quadcopter and how
it has been accomplished.
[15]

Chapter 2 will discuss some theoretical aspects concerning the Quadcopter, as well as the
previous work that has been done related to it.
Chapter 3 is all about covering the hardware characteristics and the software design, also
presenting a block diagram of the Quadcopter and the architecture of its control algorithm
illustrated in a flow chart.
The selection of components used in the Quadcopter and also the reasons behind the
decisions that have been made is explained in chapter 4.
Finally in chapter 5, the implementation and integration of both the hardware and
software is discussed, in addition to the achieved results and the future plans.
[16]

CHAPTER- 2
LITERATURE REVIEW OF UAV QUADCOPTER
2.1 Quadcopter
A Quadcopter is an aircraft that consists of four-fixed rotors placed at the ends of a cross-
shaped frame.
Figure 1 shows a schematic of a Quadcopter helping to understand how it works. Both
rotor 1 and 3 (front and back) rotate clockwise (CW) producing a torque, while rotors 2
and 4 (right and left) rotate counter clockwise (CCW) producing an opposite torque
resulting in a balanced torque across the aircraft. The four rotors would produce equal
thrust when rotating in the same speed lifting the Quadcopter in the upward direction.
[17]

Figure 1. Schematic diagram of the four rotors on a Quadcopter.
For a better understanding of the dynamics scheme of controlling a Quadcopter, figure 2
shows the degrees of freedom associated with a Quadcopter. In order to control the pitch,
the relative speed of the front and back rotors are changed, while maintaining the same
thrust on the other rotors (right and left). In the same manner, the roll is controlled by
changing the relative speed of the right and left rotors, while maintaining the same thrust
on the other rotors (front and back). Finally the control of yaw, whether clockwise or
counter clockwise, is achieved by varying the speed of the right and left rotors relative to
the speed of the front and back rotors.
[18]

Figure 2 .Types of motion.
2.2 Background:
Attempts to build a Quadcopter go back to the early 1900's, it was more of an
experimental rotary-wing plane but very similar to the concept of a Quadcopter. Such
aircraft was built by the Breguet brothers and the assistance of a professor called Charles
Richet, it flew for the first time in 1907. They called it the “Breguet-Richet Gyroplane
No.1”, and there was only one pilot on-board. The frame (chassis) of this gyroplane at the
center of it was a rectangular-shaped tubing steel to support the pilot and the engine (it
was called a powerplant at that time), from that center four arms are projected, also made
from steel, at their end were a 4-blade biplane rotor. Two sets of these rotors would rotate
clockwise and the other two would rotate counter clockwise in order to generate a
balanced torque around the frame making the aircraft vertically take off. The powerplant
of the gyroplane was Antoinette piston engine rated at 40-hp and the weight of the
aircraft was about 500 kg without the pilot. But their experimental aircraft didn't flew
well and wasn't steerable nor controllable by any means. Figure 3 shows a photo of this
aircraft.
[19]

Figure 3. Breguet-Richet Gyroplane Quadcopter
A French scientist and an engineer called Etienne Oehmichen was more successful when
he built the “Oehmichen No.2” in 1922. This aircraft was reliable and capable of lifting
an individual person with ease. This aircraft possessed four rotors and eight auxiliary
propellers (for a better directional control), powered by a 120-hp Le Rhone rotary engine.
Figure 4 shows this amazing machine showing the main components. The frame of this
aircraft is an x-shaped steel-tube with a 2-blade paddle-shaped rotors at the end of each
arm. The eight auxiliary propellers were used for various directional tasks such as; one is
mounted on the nose for steering, two are used to push the aircraft forward, and rest are
mounted horizontally for stability purposes.
At the beginning of the 1980's, Quadcopter have been getting a lot of attention as
alternatives for mini UAV applications, together with the introduction of smart
electronics, more research and development have been conducted in that area.
[20]

Figure 4. Oehmichen Quadcopter
The Draganflyer X4 is an impressive commercial Quadcopter, yet also suitable for
governmental and military usages. The frame is made from carbon fiber and so are the
rotors. This Quadcopter weighs about 680 g and has a payload capacity of 250 g. The
rotors are driven by brushless Direct Drive motors, with stall protection as a safety
feature. The X4 is packed with a total of seven sensors; three gyroscopes, three
accelerometers, and one barometric pressure sensor. The X4 has also an intuitive easy-to-
use controller, with an OLED touch screen and simple interface, which makes the
experience smooth and easy-to-grab for beginners. The mounting for the camera or any
capturing device installed features an anti-vibration design, resulting in a clear,
professional shoots and videos. A user-friendly software to show basic and advanced
real-time information monitoring, including of course a live stream of the video being
captured, is also available. Figure 5 shows the Draganflyer X4
[21]

Figure 5. Draganflyer X4 .
The Quadcopter project was inspired by the two individuals from de Holger Buss and
Ingo Busker. These two initiated their own project in 2006 and never stopped
since, building outstanding aerial platforms suitable for aerial photography, universities
(for educational and scientific purposes), and also as a hobby for enthusiasts. Their latest
aircraft is the Hexakopter featuring six rotors and a flight time up to 36 minutes with a
small payload (capable of a maximum of 1 kg payload), it weighs about 1.2 kg without
the camera. Figure 7 demonstrates the Hexakopter.
Figure 6. Hexakopter
[22]

CHAPTER-3
MODELLING OF QUADCOPTER IN PRO-E WILDFIRE 5.0
3.1 ABOUT Pro-E
Pro/ENGINEER is a computer graphics system for modelling various mechanical designs and for
performing related design and manufacturing operations. The system uses a 3D solid modelling
system as the core, and applies the feature-based, parametric modelling method.
Pro/ENGINEER is a feature-based, parametric solid modelling system with many extended
design and manufacturing applications. Assembly, processing, manufacturing and other
disciplines are using the unique characteristics of these areas. To these features by setting
[23]

parameters (including not only geometry, but also non-geometric properties), and then modify
the parameters are easy to design iterations many times, to achieve product development
.
3.2 Modeling components individually
3.2.1 ROD
First model a spar with appropriate dimensions i.e., 25* 25 cms.
Steps:
 Starting Pro/E and Creating new Part:
1. Start Pro/E Wildfire 5.0.
2. Click menu: File > New. A dialogue box will pop up as shown in Figure 7.
3. Give a new name and/or description if desired.
4. Click OK button and Pro/E will create an empty solid part as shown in Figure 7.
5. You may want to take a look of the coordinate system in Pro/E
Fig. 7 Starting Pro-E
 Selection of the planes :
1. Select the desired plane and its reference plane.
[24]

2. Here, we have selected front plane as the sketching plane.
Fig.8 Selection of planes
 Sketch and Extrude :
To make a part, the first step is to draw a sketch, then extrude it to form a solid part.
Remember, there are number of ways to do one thing in Pro/E.
As shown in Figure :
1. Click the “Front” Reference plan. This is where you draw a sketch. You can also go to
step 2 first, then chose the reference plane.
2. Then click the Sketch tool . All the information should be filled up (Figure 3)
3. Click Sketch button in Figure if you want to accept all the inputs.
4. Now Pro/E is in the Sketch mode. This will allow you to sketch in the XY plane and
extrude in the Z direction.
5. You can close the References window by click close button.
[25]

Figure no. 9 Extrude (Rod)
3.2.2 PLATE:
Model a plate with 10 * 10 cms dimensions.
[26]

Figure no.10 Plate
3.2.3 MOTOR:
Similarly, model a motor with appropriate dimensions.
Figure no.11 Motor
3.2.4 PROPELLER:
Model a propeller of 10*4.5 size.
[27]

Figure no.12 propeller
3.3 Sub-assembly
1. Place components in sub-assemblies using commands like MATE, ALIGN and
INSERT to create full product assemblies.
2. Modify assembly placement offsets
3. Create and modify assembly datum planes, coordinate systems and cross-sections.
[28]

Figure no.14 Sub-assembly of rods and plates.
Figure no.15 Subassembly of motor and propeller
3.4 FINAL ASSEMBLY:
[29]

Figure no. 16 Final Assembly
[30]

CHAPTER-4
HARDWARE CHARACTERISTICS & SOFTWARE
DESIGN
4.1 Block Diagram
The best way to start the design phase is by drawing a block diagram, which does a
great job explaining the whole system layout in short. The block diagram in figure
demonstrates the main components of the Quadcopter, in addition it also clarifies how
each component is interfaced and coupled with the other parts.
[31]

Figure no.17 Block diagram of a Quadcopter control
4.2 Mechanical Components Characteristics
In this section, the desired characteristics of the mechanical components will be
discussed. Mainly what are the characteristics and features that have been considered
while designing the Quadcopter. Of course also some technical aspects will be
mentioned.
4.2.1 Frame Characteristics
The most suitable way is to begin with is the skeleton of the Quadcopter, the frame. The
frame is
considered the largest (in volume) component used in the Quadcopter and a very
important one. Choosing a frame to fulfill the required need is essential, critical, and also
[32]

not simple. The frame should be light-weight yet strong to tolerate possible accidents and
crashes, it has also to be thin.
Light: a feature that is quite important in aircraft and vehicles, and in Quadcopter it is no
exception. Ultimately the goal is to reach the best possible flight time, and to do so the
weight of the frame should be minimal. This also would assure a better stability and
controllability of the Quadcopter.
Strength: having a frame that is sturdy and strong is vital, as the Quadcopter could crash,
or have an accident due to a wrong landing.
Thin: it is quite critical to have a frame that is thin due to several issues; since the
Quadcopter has four motors spinning at a very high speed, consequently during the flight
those motors will eventually get very hot (depending on flight conditions). Hence, having
a proper air flow is a must to cool down the inner components of the motors and prevent
any damage due to overheating. Another upside of a thin frame is that the vertical air
flow generated by the propellers won't be hindered by a wide frame, contributing in a
better flight stability.
Length: Another issue that should be discussed about the frame, is its length. The focus
in this case is the distance between the middle point of each opposite motor. It's preferred
to cut down this distance as much as possible due to several reasons; it's a good way to
make the power needed from each motor to stabilize and/or fly the Quadcopter around.
Another good side is that it would enhance the controllability, maneuverability, and also
contribute in reducing the overall frame weight.
Now since the design of the Quadcopter would be an x-shaped, at the center of the shape
should exist a plate (bed) where the on-board controller would rest on it and then covered
[33]

to ensure protection of anything resting there, from cables to the controller itself. This
plate should also be sturdy and at the same time light-weight.
To ensure safety and avoid severe damage of the Quadcopter, it has been a priority to
also design some safety features. First off a proper landing gear is important to be
installed. In case of a faulty landing or an error during flight time, the landing gear should
be able, or at least, minimize the damage and impact on the whole Quadcopter. A flexible
landing gear would be a good way to assure this.
Landing Gear: Next is the fact that the exposed propellers are absolutely dangerous for
the Quadcopter itself and the humans around it. Those propellers are, as said before,
spinning at very high speeds during flight and would certainly and seriously hurt
someone badly if something went wrong. The damage could affect the Quadcopter itself,
say the Quadcopter hit a wall, an object, or an obstacle, the propellers would break and be
shattered. The motors could take damage and become unusable. Plus also the shattered
pieces could hurt anyone around them. Such reasons are quite persuasive to consider
designing protection around the propellers, at least during flight time and the testing
phase. And could be removed when the Quadcopter is ready and reliable.
4.2.2 Propellers Characteristics
The mechanical lifting element of the Quadcopter are the propellers. They do come in
different sizes, shapes, and materials; which makes the decision somehow flexible in
choosing one. High quality propellers are made by different manufacturers to deliver
great performance of lifting power at a very small weight; to minimize the torque needed
for spinning them by the motor's rotor.
As mentioned propellers are manufactured from a variety of materials such as; plastic,
which is cheap, available, and light, but is by nature fragile meaning it could be damaged
or broken easily. Wood is another example, it is tough and mid-priced but is certainly
[34]

heavier than plastic. Lastly is the carbon fiber which is tough and light-weight but more
expensive than the previous two types.
Choosing a suitable size is quite crucial in the design of the Quadcopter, since it affects
the power consumption, the overall weight, and how sturdy and reliable (stable-wise) the
Quadcopter is. Increasing the size of the propellers means higher thrust delivered, but that
comes at the cost of more torque required to spin them by the motors. Having that in
mind, the criterion for choosing the propellers is mainly dependent on the model that is
being built and its overall weight. As the goal states, the Quadcopter should be about 1.4
kg and propellers with the size 10 inches are appropriate.
Importantly is the fact that four propellers are needed, but with a pair being oriented for
clockwise (CW) direction and the other pair for the counter-clockwise (CCW) direction.
4.3 Electrical & Electronic Characteristics
The design of electrical and electronic components is absolutely an exhausting
phase, picking components and parts that will cooperate and be interfaced together to
make the Quadcopter successful was filled with hardships. As each of these components
would be synchronized and affected by the others, in addition to the fact that each
component is a main player in the design process, care and precision are a must. In this
section a thorough discussion about this phase will be mentioned.
4.3.1.1 Motors Characteristics
The motors are no doubt one of the most important elements in the Quadcopter, they are
the “muscles” of it. With that in mind it's quite important to choose the right motors to
do the job, as the impact of those is huge on how satisfying and good the final outcome
is.
Brushless DC (BLDC) motors have several advantages over brushed motors and are a
superior choice; due to the lack of mechanical parts and the absence of brushes, as
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mentioned before, the BLDC motors are more efficient (converting electrical to
mechanical energy) than brushed DC motors since there are no friction losses due to the
brushes. The BLDC motors are also less subjected to service and maintenance, again
because of no friction, the mechanical wear is eliminated which guarantees a longer life-
time and better reliability. Less noise generated when operating and since the motor
would be covered in a housing, any cooling issues are almost solved. A BLDC motor's
only disadvantage is its high cost in comparison with a brushed DC motor, as it would
require a sophisticated electronic speed controller (ESC) to run it and control its speed.
Also the manufacturing of a BLDC motor isn't as simple as the brushed DC motor. On
the long run though, the cost of a BLDC is theoretically lower keeping in mind that it has
a longer life-time than a brushed one which would compensate its higher cost.
For the Quadcopter, choosing a BLDC motor is definitely a righteous call, but that's not
everything. Since the Quadcopter is a remote-controlled (RC) propelled aircraft project, a
specific type of a BLDC motor called out runner (the outer shell spins around the
windings) is very suitable to operate the Quadcopter with ease due to several factors;
despite the fact that this type is slower than in runners BLDC motors (the rotational core
is housed in the motor's can) but that means that the torque produced is much higher,
this exactly is the selling point why out runners are a perfect choice to run the
propellers. It's also quite efficient from a weight point of view, because there is no need
for a gearbox, ridding the Quadcopter from it's complexity, noise, inefficiency, and extra
weight.
[36]

Figure no 20. A Brushless DC outrunner motor.
4.3.1.2 Electronic Speed Controller (ESC) Characteristics
ECS's are required to run the BLDC motors in the Quadcopter. The ESC is a standalone
chip that's connected to the receiver's control channels and then coupled with the BLDC
motor.
For a better understanding of the ESC, it's more conventional to consider it as a pulse-
width modulation (PWM) controller for the BLDC motors. PWM in short is a great way
of controlling some modern electronics such as a BLDC motor, a fast variation between
the motor being fully off and fully on powered, more conveniently described as a
percentage called the duty cycle. Controlling the duty cycle means controlling the speed
of the BLDC motor without any losses and also without affecting the load.
[37]

4.3.2 Sensors Characteristics
4.3.2.1 Gyroscope Characteristics
At the beginning of the project, the aim was to achieve a self-stabilized Quadcopter, in
order to achieve that there has to be a kind of feedback that tells the microcontroller that
the Quadcopter is tilting or leaning. This special feedback is achieved through a
gyroscope. A gyroscope is a sensor that measures the angular rate or velocity (speed of
rotation). When rotating it also gives a positive or negative readings, and while stationary
gives a constant value.
Choosing an appropriate gyroscope is dependent on a number of factors; the gyroscope
should be fast and responsive, in other words it should be able to detect minimal changes
in the angular velocity in order to compensate the errors faster which would guarantee the
prevention of the accumulation of errors. It should also be small, and light-weight,
usually Micro Electro-Mechanical Systems (MEMS) manufactured sensors do a great job
featuring these two aspects. And because of the existence of noise, a built-in filter is also
a plus, in addition to a conditioning circuit embedded on the chip that would help a lot in
cutting extra parts and complexities.
Since the Quadcopter is governed by three degrees of freedom (pitch, roll, and yaw), a 3-
axis gyroscope is needed.
4.3.2.2 Accelerometer Characteristics
An accelerometer is a sensor capable of measuring the amount of acceleration, also could
measure the tilt. Implementing the accelerometer and the 3-axis gyroscope together on a
single chip yield the inertial measurement unit (IMU). This unit utilizes both sensors to
do an outstanding job in keeping the Quadcopter as much stable and level as possible,
plus having two sensors on one chip reduces any extra space needed.
[38]

Knowing that the implementation (from a code point of view) isn't anything but hard and
complex, nevertheless utilizing some of the true potential of the accelerometer would
affect the final outcome and results. A 3-axis accelerometer would seem to do that job.
4.3.3 Transmitter & Receiver Characteristics
For the pilot to command the Quadcopter from the ground, a transmitter or a remote-
control (RC) is needed. This should have a good range and both a pre-programmed and
user-programmed channel mixing for a better flexibility and usage. The number of
channels is also an aspect that should not be left out, having a proper amount of channels
is always a plus, as it would greatly enhance the features and tweaks that could be
utilized and later on added to the Quadcopter.
The receiver, which is used to get the commands sent from the transmitter by the pilot,
would be directly coupled with the microcontroller through the PWM I/O pins. Having a
receiver with auto channel and frequency selection seems suitable, offering a user-
friendly solution.
4.3.4 Microcontroller Unit (MCU) Characteristics
Figure no.21 Microcontroller
[39]

The on-board controller is without a doubt a vital component in the Quadcopter. The fact
that the on-board controller will be the one responsible for dispatching a variety of
instructions to the other components, yet also receive certain commands from the pilot
and the feedback coming from the sensors. A proper microcontroller would accomplish
such tasks if properly selected. Definitely a microcontroller is the way to go, because of
its capabilities despite its weight and size.
With that in mind, the selection of a proper microcontroller is critical and should be based
on a specific criteria, summarized as follows:
• Speed of operation; in other words how fast and agile is the processing power? Having
a suitable computational power in the Quadcopter is a must, because during flight time,
the controller should be very responsive and quick to guarantee a stable and a well-
behaving flight.
• Cost; both the hardware and the software to run it. Sometimes the cost of these could
and will eventually mean the need to compromise.
• Power needed to run it; yet another reason to maximize the flight time, the
power consumption of the controller should be as minimal as possible.
• Data storage; i.e. Memory. The controller should provide enough memory to handle
the program and code embedded. A project could fail because of the lack of memory.
• Number of I/O ports; when designing the system, one should possess the knowledge of
how many inputs and outputs are needed. Selecting a controller that shorts in input or
output ports could cause unneeded troubles.
[40]

• Analog capabilities; some controllers lack these such as; ADC, DAC, or a comparator.
In such case this would require to have extra few components and undesired clutter.
• Serial communication; which communication protocol is used to interface the
microcontroller? USB would be a great solution, since it's an industry standard and
readily available.
• Development tools; extra tools and programs that might be needed to fully utilize the
microcontroller. Again it could be a cost point of view, or its availability.
• Environmental conditions; where would it be mounted? Temperature and humidity
issues should also be considered.
With the help of these guidelines, the selection of the microcontroller is clearer and more
convenient. Importantly in the case of the Quadcopter that the microcontroller selected
should be powerful, light- weight, easy to interface with a computer and prototype which,
has enough I/O ports, and easy on the pocket.
4.3.5 Battery Characteristics
Having four motors in a Quadcopter that produce high thrust power, that means
high current consumption is required. So a battery with high current capacity and
discharging rate is needed. Such batteries are available in the market but with much
larger scale and weight than normal batteries, and minimizing the weight of components
on a Quadcopter is a very crucial matter to consider so that an efficient stable flying
system can be achieved. Also it shouldn't be missed that the wires used in the connections
between motors, ESC's, and batteries are able to withstand high current discharge.
[41]

4.4 Software & Control Design
After selecting the right hardware components, the next step is to have a proper design
for the code that will run on the Quadcopter. This phase is the hardest of all and needs so
much patience and constant tuning and monitoring. Having a snappy control loop is
essential as the Quadcopter tries to self-stabilize itself, without such a loop, the flight
could be sluggish with a huge amount of errors, which will be also accumulative and
eventually would result in a crash with unexpected consequences.
Starting off with a simple, yet very enriched flow chart of how should the program
embedded in the micro controller look like and behave. A flow chart is very similar to the
block diagram; brief and comprehensive. In figure 11 the flow chart shows the basic steps
and processes needed in the main code.
Figure no 22 Control algorithm flow chart.
To summarize the flow chart, it begins with providing the power through the battery, at
this instance hardware components will initialize and boot. After that the sensors will be
calibrated, taking the nominal value that they “see” and consider it as the reference. The
next two steps are mainly getting the values that the sensors read and then sending those
values to the proportional-Integral (PD) which will get the error and output the final
[42]

values with the help of the desired values from the transmitter and receiver. To conclude,
mixing is the process of sending the commands to the motors based on the desired input
plus the output value generated from PD.
CHAPTER- 5
SELECTED COMPONENTS’ SPECIFICATIONS
In this chapter reasons and justifications to the chosen parts and components will be
made.
5.1 Selected Mechanical Components
5.1.1 Frame
The frame used in the Quadcopter, is made of four aluminum drilled rods with square
cross-section and two center wooden plates. The frame weighs about 150 g, depending
also on the type and number of screws used. The distance between the centers of two
aligned motors is 50 cm and from the center of gravity is 25cm. To mount the
microcontroller and the other components that will be interfaced with it, a custom-made
wood plate is used.
[43]

Figure no.23 the frame set used
5.1.2 Selected Propellers
As for the propellers used, they are slow fly (SF) 1045 i.e., 10*4.5 units for clockwise
and counter clockwise rotation. Figure 13 shows a pair of them.
Figure no.24 A pair of the SF 1045 propellers.
5.2 Selected Electrical & Electronic Components
[44]

5.2.1 Selected Actuators
5.2.1.1 Selected Motors
The motors selected to actuate the Quadcopter are the BLDC out runners type 750 KV.
Weighing each 78 g, these motors are capable of 750 rpm/Volt, maximum efficiency of
80%, and a maximum current of 18A. Each motor can produce a maximum thrust up to
1000 g +.
Considering the 2:1 ratio between motors thrust power to Quad copter’s weight is
important. Having a light-weight Quadcopter and relatively strong motors implies the fact
that the control of it would be harder since the overrated power of the motors ratio to the
Quadcopter weight would easily produce an unstable flight, and therefore the control
algorithm has to be accurate. No compromise. The amount of rpm/Volt is mainly
dependent on the Quadcopter's weight and size, as for bigger sizes low rpm/Volt is better
(higher torque) and for small sizes the opposite.
5.2.1.2 Selected Electronic Speed Control (ESC)
The required ESC needed to run the motor is 20 A, the Mystery cloud are capable to
deliver upto 20 A, which is quite enough and safe. Weighing about 25 g and with a lot of
features such as; superior current endurance, protection features, different operating
modes depending on the aerial platform used, and a throttle range that can be
programmed and compatible with all transmitters available in the market.
[45]

Figure no.25 the ESC picked
5.2.3 Selected Transmitter
The transmitter used in the Quadcopter is the same one used in most remote-control (RC)
toys. Having multiple channels and user-defined channel mixing makes it a suitable
choice.
[46]

Figure no.26 Fly sky FS-CT6B 6-channel Transmitter
5.2.4 Selected Receiver
As for the receiver, the R16SCAN is selected. Featuring SCAN technology which
enables the receiver to auto-detect the optimum frequency needed without any extra
steps. It weighs only 17g.
Figure no.27 Fly-sky FS-R6B Receiver
5.2.5 Selected Microcontroller Unit (MCU)
[47]

The Multiwii SE V2.0 is a gyro/accelerometer based flight controller that is loaded
with features. With expandability options and full programmability, this device can
control just about any type of aircraft. This is the ideal flight controller for your multi-
rotor aircraft.
Figure no.28 Multiwii SE V2.0 MCU
Features:
• Small size, 35x35mm mounting holes
• 6 input channels for standard receiver and PPM SUM receiver
• Up to 8-axis motor output
• 2 servos output for PITCH and ROLL gimbal system
• Can utilize a servo's output to trigger a camera button
• FTDI/UART TTL socket for debug, upload firmware or LCD display
• I2C socket for extend sensor, I2C LCD/OLED display or CRIUS I2c-GPS NAV
board
• Separate 3.3V and 5V LDO voltage regulator
• ATMega 328P Microcontroller
• MPU6050 6 axis gyro/accelerometer with Motion Processing Unit
• HMC5883L 3-axis digital magnetometer
• BMP085 digital pressure sensor
• On board logic level converter
[48]

Flight mode:
• One of the following basic mode
- Acro
- Level
- Alt Hold
- Head Lock
• Optional mode
- HeadFree (CareFree)
- GPS Hold (Need GPS receiver + I2C-GPS NAV Board)
- GPS Return to home position (Need GPS receiver + I2C-GPS NAV Board)
Specs:
Dimension: 40x12x40mm
Weight: 9.6g
Fixing hole spacing: 35mm (It can be changed to 45mm by CRIUS Distribution
Board)
Hole diameter: 3mm
5.2.6 Selected Battery
LiPo (or Lithium Polymer) batteries are rechargeable batteries, normally are composed of
several identical secondary cells in parallel addition to increase the discharge current
capability. They provide high current capacity and discharge rate to weight ratio. They
have also great life cycle degradation rate.
A LiPo battery package can have more than 1 cell, the voltage of a LiPo cell varies from
about 2.7V (discharged) to about 4.23V (fully charged). The battery or cell
capacities are rated in ampere hours(Ah) or mill ampere hours(mAh). And they are
also rated in C which is the maximum discharge rate.
The BLDC motors have a continuous current discharge ranging between 4–10 A per
motor, so maximum discharge is (10 A*4) = 40 A. And the average current drain during
[49]

the flight is 5.5 A per motor (5.5 A * 4) = 22 A. A 2200 mAh 20C battery was chosen for
testing the Quadcopter and it weighs
180 g.
• The battery has maximum discharge of (2.2 Ah * 20) = 44 A, and can run the
Quadcopter for
(2.2 Ah * 60) / 22 A = 6 minutes (theoretically). This battery is illustrated in figure
CHAPTER 6
MECHANICAL DESIGN
6.1 Quadrotor modelling
[50]

The first step before the control stage is the adequate modeling of the system dynamics. This
phase will hopefully facilitate the control of the aircraft as it will provide us with a better
understanding of the overall system capabilities and limitations. The current chapter will guide
us through the equations and techniques used to model our quadrotor and its sensors,
providing the mathematical basis for the application of the system dynamics in a simulation
environment.
6.2 System dynamics
Writing the equations that portray the complex dynamics of an aircraft implies first defining the
system of coordinates to use. Only two reference frames are required, an earth fixed frame and
a mobile frame whose dynamic behavior can be described relative to the fixed frame. The earth
fixed axis system will be regarded as an inertial reference frame: one in which the first law of
Newton1 is valid. Experience indicates this to be acceptable even for supersonic airplanes but
not for hypersonic vehicles. We shall designate this reference frame by ON ED (North-East-
Down) because two of its axis (ux and uy ) are aligned respectively with the North and East
direction, and the third axis (uz ) is directed down, aligned towards the center of the Earth
(Figure 3.1.1). The mobile frame is designated by OABC, or Aircraft- Body-Centered, and has its
origin coincident with the quadrotor’s center of gravity.
An object that is not moving will not move until a net force acts upon it. An object that is moving
will not change its velocity (accelerate) until a net force acts upon it.
The rotational velocity of Earth must not be neglected for hypersonic flight.
[51]

Figure no.30 NED and ABC reference frames
In control theory, knowledge about the dynamic behavior of a given system can be acquired
through its states. For a quadrotor, its attitude about all 3 axis of rotation is known with 6 states:
The Euler angles [φ θ ψ] (Roll – Pitch – Yaw as seen before in Figure (1.2.1)) and the angular
velocities around each axis of the OABC frame [P Q R].
Yet another 6 states are necessary: the position of the center of gravity (or COG) [X Y Z ]
and respective linear velocity components [U V W ] relative to the fixed frame. In sum, the
quadrotor has 12 states that describe 6 degrees of freedom.
Unsurprisingly, we must deduce the equations describing the orientation of the mobile frame
relative to the fixed one, which can be achieved by using a rotation matrix. This matrix results of
the product between three other matrices (R0 (φ), R0 (θ) and R0 (ψ)), each of them
representing the rotation of the ABC frame around each one of the ON ED axis [22]:
[52]

( ; ( ; (
S ( ( (
S =
Where S is the rotation matrix that expresses the orientation of the coordinate frame OABC
relative to the reference frame ON ED. To mathematically write the movement of an aircraft we
must employ Newton’s second law of motion. As such, the equations of the net force and
moment acting on the quadrotor’s body (respectively Fnet and Mnet) are provided:
+
[ +w’
where I is the inertia matrix of the quadrotor, v is the vector of linear velocities and ω0
the vector of angular velocities. If the equation of Newton’s second law is to be as complete
as possible, we should add extra terms such as the Coriolis, Euler and aerodynamic forces (e.g.
wind), but to keep the model simple, and also because the quadrotor is not supposed, at this
stage, to go very far away from the ground station, these forces will not be incorporated in
the modeling process. The force of gravity (Fg) is too significative to be neglected, thus it is
defined by:
[53]

= [ mg [
The force of gravity together with the total thrust generated by the propellers (FP) have
therefore to be equal to the sum of forces acting on the quadrotor:
Fg+ =Fnet
(3.7) Combining equations (3.4), (3.6) and (3.7) we can write the vector of linear
accelerations acting on the vehicle’s body:
+ g
where [FP x FP y FP z ] are the vector elements of FP . Assuming the aircraft is in a
hovered flight, in such a scenario there are forces acting only in the z axis of quadrotor,
corresponding to the situation we have the engines trying to overcome the force of
gravity to keep the aircraft stable at a given altitude:
FPz = T1+T2 + T3 + T4)
(3.9) Note that the minus sign means the lifting force is acting upwards, away from the
surface (note that the positive axis of the ON ED is point downwards)
Working now on Newton’s second law for rotation, the inertia matrix is given by:
I
Assuming the quadrotor is a rigid body with constant mass and axis aligned with the
principal axis of inertia, then the tensor I becomes a diagonal matrix containing only the
principle moments of inertia.
[54]

I
Joining 3.1 and 3.5 we get,
+
Consequently we will have,
+
Information on the moments acting on the aircraft cab be provided by,
= (
= ( )
= ( + )
Where, is the distance of cog of aircrafts and is constant that relates
thrust and propeller.
[55]

6.3 Kinematic equations and Euler angles
In this section we will study the kinematics of the quadrotor. The first stage of kinematics
analysis consists of deriving position to obtain velocity. Let us then consider the position vector
→ −r , which indicates the position of the origin of the OABC frame relative to ON ED :
X + Y
If we derive each component in we can onbtain the instantaneous velocity of relative
to .
+ +
To find out the aircrafts linear velocity v’ in the fixed frame we can use:
Where we can take full advantage of orthogonality of S, meaning its inverse is equal to its
transpose:
[56]

The flight path of the quadrotor in terms of [X Y Z] can be found by integration of equation 3.22.
To perform this integration, the Euler angles φ, θ and ψ must be known. However, the Euler
angles themselves are functions of time: the Euler rates φ˙, θ˙, and ψ˙ depend on the body axis
angular rates P, Q and R. To establish the relationship between [φ˙ θ˙ ψ˙ ] and [P Q R] the
following equality must be satisfied:
+ Q φ˙ + θ˙ + ψ˙
Note that although it may appear that the Euler rates are the same as angular velocities, this is
not the case. If a solid object is rotating at a constant rate, then its angular velocity →−ω will be
constant, however the Euler rates will be varying because they depend on the instantaneous
angles between the coordinate frame of the body and the inertial reference system (e.g.
between OABC and ON ED ). The Euler angle sequence is made up of three successive
rotations: Roll, Pitch and Yaw. In other words, the angular rate φ˙ needs one rotation, θ˙ needs
two and ψ˙ needs +three:
R ( + R ( ) R ( + R( )
Therefore,
Solving for the euler angle rates yields the desired differential equations:
T
T
where T is the matrix that relates the body-fixed angular velocity vector →−ω and the rate of
change of the Euler angles.
[57]

6.4 Motor Alignment
As previously mentioned, the act of mounting the motor mounts to the frame was
extremely difficult due to the fact that the holes needed to be drilled to within +/- .1o of
each other. Any successful flying device must be perfectly balanced, and this is very
prevalent when dealing with a quad rotor. In order to achieve a balanced vertical flight,
the group needed to be certain that the motors were perfectly straight. If the motors were
not perfectly aligned, achieving a balanced, smooth flight would be nearly impossible.
With this in mind, the group devised a way to be sure that all the motor mounts were
aligned correctly. By setting the frame of the quad rotor on a flat surface, the group used
a T-square held against the motor mounts. If the mounts were directly against the edge of
the square, then the mount would be aligned in a right angle.
6.5 PROPELLER BALANCING
Due to the fact that the propellers are operating at such a high RPM, it is crucial to the quad
rotors performance that the propellers are balanced. Although theoretically the propellers are
designed to have symmetric blades, in reality there are slight imperfections. These
imperfections cause the propellers to vibrate uncontrollably, making smooth flight almost
impossible. By balancing the propellers, vibrations can be significantly reduced.
The group balanced the propellers by examining the relative weight distribution of each
propeller. There are several types of commercially available propeller balancing devices, but a
similarly effective device was made. The method used consisted of attaching the propeller to a
spindle held up between two blocks, allowing the propellers to rotate freely. If one of the blades
is heavier than the other, then the propeller will rotate towards the heavier blade. In such a case
the blades trailing edge was sanded down to compensate for the mass difference. Once the
blades weights were evenly distributed, the propeller balanced horizontally.
[58]

6.6 Total Balancing
The quad rotor, which includes the hub, spars, and motor mounts, was carefully designed and
assembled with the idea of having a helicopter which is as close to perfect in terms of its weight
distribution throughout the entire aircraft. As previously mentioned, achieving a steady and
controllable flight is almost impossible to achieve unless the aircraft is as close to perfect
balance. The addition of the electronic components and battery onto the frame of the quad
rotor leaves its weight distribution inconsistent throughout. As a result, the group has devised a
way to make sure that the frame is as balanced as possible.
The way to do this is by attaching a piece of string to the center of the hub and allowing the
quad rotor to float freely. If the weight is not evenly distributed, then the quad rotor will lean
towards the heaviest part. The battery packs, which are mounted below the central hub by
rubber bands, were then adjusted to ensure the quadrotor was balanced in the x and y axes.
CHAPTER 7
OPERATION AND CONTROL THEORY
7.1 Forces acting on a Quadcopter
[59]

Effect Source
Aerodynamic effects - Propeller rotation
Inertial counter torques - Change in propeller
rotation speed
Gravity effect - Center of mass position
Gyroscopic effects - Change in orientation
of the rigid body
- Change in orientation
of the propeller plane
Friction - All helicopter motion
Figure no.32 Forces acting on a quadcopter
7.2 Quadrotor operation
Each rotor in a quadrotor is responsible for a certain amount of thrust and torque about its
center of rotation, as well as for a drag force opposite to the rotorcraft’s direction of
flight. The quadrotor’s propellers are not all alike. In fact, they are divided in two pairs,
[60]

two pusher and two puller blades that work in contra-rotation. As a consequence, the
resulting net torque can be null if all propellers turn with the same angular velocity,
thus allowing for the aircraft to remain still around its center of gravity.
In order to define an aircraft’s orientation (or attitude) around its center of mass,
aerospace engineers usually define three dynamic parameters, the angles of yaw, pitch
and roll. This is very useful because the forces used to control the aircraft act around its
center of mass, causing it to pitch, roll or yaw. Changes in the pitch angle are induced by
contrary variation of speeds in propellers 1 and 3, resulting in forward or backwards
translation. If we do this same action for propellers, we can produce a change in the roll
angle and we will get lateral translation. Yaw is induced by mismatching the balance in
aerodynamic torques (i.e. by offsetting the cumulative thrust between the counter-rotating
blade pairs). So, by changing these three angles in a quadrotor we are able to make it
maneuver in any direction.
Figure no.33 Yaw, pitch and roll rotations of a common quadrotor.
[61]

Figure no 34 Illustration of the various movements of a quadrotor.
7.3 P.I.D control
The quad rotor will use a Proportional-Integral-Derivative control system, which will be tuned to
determine the optimum response and settling time. The PID controller Eq. (4.9) is a closed-loop
feedback system which will output a control signal u and receive feedback from the inertial
sensors. The controller then calculated the difference between the desired position and
orientation and the current position and orientation and adjusts u accordingly. The equation for
a PID controller is as follows:
U = � + I + D
[62]

7.3.1 Proportional, Integral, Derivative (PID) Controller
PID, or proportional-integral-derivative controllers are loop feedback controls that aim to
correct for a given error. Often, the effect of a PID is modeled as a step response. One PID
control is needed for each parameter to be corrected. In our case, we need a PID loop for yaw,
pitch, and roll. Future designs might implement PID for altitude and x/y position as well. In the
embedded environment, the proportional, integral, and derivative terms are calculated as
follow:
P = desired – actual
I = I + actual
D = current error – past error
Note that the derivative term can also be determined by accessing the direct ADC values from
the rate gyroscopes for a given axis of rotation.
Each of the three terms has a gain KP, KI, or KD that is tuned to minimize rise time to the step
input and to minimize oscillation and overshoot. For each of the three Euler angles, we
compute a sum comprised of the gains and their corresponding terms, e.g.
Pitch sum = KP*P + Ki*I + KD*D
At the end of the PID loop, the appropriate summations were added and subtracted from each
of the four motors as seen in the code snippet below. The thrust Floor term corresponds to the
thrust that the user commands on the joystick.
PWM_MOT1 = thrust Floor – roll sum + yaw sum;
PWM_MOT2 = thrust Floor + pitch sum – yaw sum;
PWM_MOT3 = thrust Floor + roll sum + yaw sum;
PWM_MOT4 = thrust Floor – pitch sum – yaw sum;
[63]

The entire PID loop must be completed at a relatively high frequency to ensure fast motor
response. Without a fast PID response the quadrotor will not properly stabilize.
7.4 Inertial Measurement
Inertial Measurement Systems sense inertial forces on a body and from those forces linear and
angular position and velocity can be calculated. There are two types of INS: initially stabilized
and strap down system. The difference comes from the frame of reference the unit is aligned to.
In an inertially stabilized unit the gyroscopes remain fixed in reference to an inertial (navigation)
reference frame (Fig. 2) and do not rotate with the vehicle which allow it to rotate on all three
axes; The gyroscopes do not measure angles directly, they are only used to keep the unit aligned
with the reference frame. In a strapped-down system the gyroscopes rotate with the body, and
by integrating angular velocities from an initial position the orientation and position of the
vehicle can be determined.
7.5 Control inputs
The Quadcopter is an aerial system that uses four propellers to generate lift. Quadcopter that
can be classified as a type of helicopter. Most Quad-Rotors use fixed-pitch blades as opposed to
most commercial helicopters. The system is controlled by varying the rotational velocity of each
of the rotors and thereby changing the thrust and torque produced.
[64]

Figure no.35 Controls in accordance with the transmitter
The Quadcopter is designed for manual control i.e. human control with visual feedback and it is
thus not possible to directly control the rotational velocity of the individual rotors. The
Quadcopter features several different modes of control but in the following only the Heading-
Hold mode will be addressed. For a thorough description of the other modes see G on page 114.
The Quadcopter flown in Heading-Hold mode utilizes a on-board control circuit that manages
the rotational velocity of the four rotors and adjusts the velocity based on on-board sensory
data. The human operator is only able to control the angular velocities of the Quadcopter along
the three body-axis and the generated thrust. This allows a skilled operator to control the
attitude and position of the platform thus enabling the operator to maintain the Quadcopter in
hover.
7.5.1 ROLL:
Roll is when the quadcopter performs a rotation around the x-body axis. This is achieved by
changing the angular velocity of the rotors on the y-body axis that is rotor 2 and 4 while
maintaining the same angular velocity on rotor 1 and 3. If the desired rotation is positive the roll
is performed by increasing the angular velocity of rotor 2 and decreasing the angular velocity of
rotor 4. This results in a positive roll or rotation around the x-body axis. The rotor velocities
related to this maneuvers are illustrated in figure
[65]

Figure no.36 Roll control
7.5.2 PITCH:
Pitch is when the QUADCOPTER performs a rotation around the y-body axis. This is achieved by
changing the angular velocity of the rotors on the x-body axis that is rotor 1 and 3 while
maintaining the same angular velocity on rotor 2 and 4. If the desired rotation is positive the
pitch is performed.by increasing the angular velocity of rotor 1 and decreasing the angular
velocity of rotor 3. This results in positive pitch or rotation around y-axis body.
Figure no.37 Pitch Control
7.5.3 YAW:
[66]

Yaw is when the Quadcopter performs a rotation around the z-body axis. This is achieved
mismatching the torque generated by the Quadcopter rotors. During normal flight the net
torque acting on the platform body is zero as the rotors along the x-body axis and y-body axis
apply the same amount of torque to the platform. If the torques applied along the axis are
mismatched the platform will perform a rotation around the z-body axis. If the desired rotation
is positive the yaw is performed by increasing the angular velocity of rotor 2 and 4 while
decreasing angular velocity of rotor 1 and 3. This results in a positive yaw or rotation around the
z-body axis. The rotor velocities related to this maneuver are illustrated in figure.
Figure no.38 Yaw Control.
CHAPTER-8
[67]

IMPLEMENTATION & RESULTS
8.1 Assembly
Assembling and connecting all the components of the Quadcopter is a process that needs
extra attention.
Starting with the frame which consists of four Aluminum parts all screwed and tightened
up with the center plate.
After that comes the soldering part; where all the needed soldering was made for the
electronic parts to be connected properly; For the PCB where the sensors will be
mounted, wires which are divided to connect the ESC’s with the battery.
When connecting the Motors and ESC’s together, the direction of rotation of each motor
should be considered.
A custom-made base platform was made to hold the controller on the center plate.
All connections were made between the electronic components and the controller. Then
the
Components were mounted together on the center plate of the frame. An empty CD-ROM
holder is used to protect all the sensitive electrical components of the Quadcopter.
The plastic door stoppers were used as landing gears and attached to the Quadcopter
frame.
8.2 Software & Control Algorithm
[68]

This section includes a brief information since the development of the project will
continue and further additions will be made, which obliged the investigators to keep the
main controlling algorithm and software confidential.
The Quadcopter controller was programmed using in built program. Multiple classes
were created to divide the work of each part of the program to keep everything neat and
simple, and to improve its functionality.
When the battery is connected to the system, the controller starts as follows:
• The process starts by initializing all the hardware, variables, classes & subclasses
needed in the system.
• The sensors are calibrated by reading their values at standstill position. These values
are considered as the zero values to be compared with any new values.
• PWM signals are read by the receiver.
• The pilot activates the motors by a specific combination of signals sent to the
controller from the transmitter.
• New values of sensors readings are compared to the original values to calculate error.
• The PID controller receives the error and produces an actuationg signal for the degrees
of freedom.
• The mixing formula is executed to adjust the motors speed in order to give the
Quadcopter, the required direction,
8.3 Flight Testing & Results
8.3.1 Preflight Testing
Before the Quadcopter could be tested in free flight, it had to be determined that it would
not respond in a way which would damage itself. First, all of the sensors were connected
to the quadcopter, but not actually mounted on it. This allowed manipulation of the
sensors while allowing the motors to run, but prevented the Quadcopter from actually
moving. This was a
[69]

qualitative test simply to ensure that the motors were responding quickly to variations in
attitude and altitude.
The second test calibrated the hover thrust. The helicopter was attached to a scale and
thrust was increased until the thrust canceled out the weight.
8.3.2 Flight Attempts
The Quadcopter is still going through flight testing which includes tuning of the damping
constants and tweaking of the code to get the most accurate data out of the sensors. The
rangefinder seems to have problems where certain distances are accurate to within a few
millimeters while others can be off by more than a centimeter.
8.4 Our Future Work & Development
• Implementing a better control algorithm using accelerometers to achieve better
stability results.
• Live feedback using wireless technology for various applications; real time aerial
video, image processing, reading different sensors data & battery capacity monitoring.
• Using image processing as an extra sensor to control the movement of the Quadcopter
and minimize the drifting.
• Minimizing the cost of building one by using cheaper components.
• Adding GPS which will make a great method in holding a current position, setting a
destination point or a way point for the Quadcopter to follow. Including using geo
tagging for different applications.
Additional sensors can be added beside the main sensors like pressure & magnetometer
sensors to control the heading and altitude of the Quadcopter, which will result in a
superior stable flight.
8. CONCLUSION
[70]

We have successfully met our design goals and demonstrated autonomous flight. The
main objective of this was to model and control a quadrotor prototype, having a tri-
axis accelerometer and a compass as its sensors.
In the first phase of this, objectives were defined for the quadrotor design, and based on
them a study was carried out on the electronics that would be part of the aircraft. This
analysis resulted in the construction of a quadrotor capable of achieving a flight.
Knowing the characteristics of our quadrotor, we proceeded to the modeling of the
aircraft’s dynamics for implementation of the resulting equations in a computer
simulation environment. Thus, we found that the system is completely controllable
when all states are available.
Joystick and the quadrotor’s control unit, the Arduino. Unfortunately, the quadrotor
displayed an unstable behavior. It was assumed that the lack of inclusion of the Pulse-
Width Modulation signal resolution in the simulations could be the reason why this
instability had not been foreseen. After introducing this new element in the simulation,
we found nevertheless that the controller could still drive the system to the intended
reference, although with a little more difficulty. This information led us to analyze the
noise coming from the sensors with the motors running, which proved to be the
source of the problem.
All the work done so far shows only that there are several aspects of the control process
that need to be corrected/improved in order to make a controlled flight for this prototype
possible. In particular, the inclusion of 3 gyroscopes (one for each axis of rotation)
should be considered, which together with the tri-axis accelerometer, form a
combination of sensors that has already been tested in quad rotors, allowing for very
good control over its pitch and roll angles. The idea is that with gyroscopes we can
determine orientation, but they drift over time (long-term errors), which is something we
can correct with accelerometers (short-term errors, i.e. They are very noisy). But even
then, we would need something else to correct the drifting yaw angle from the gyroscope,
which could be done with a magnetic compass. The long-term idea is that adding a
greater number of sensors, in addition to those suggested, can only improve the quality
and quantity.
[71]

It would also be interesting to develop the simulations further by including new
elements such as aerodynamic forces (i.e. Wind), collisions and other types of control
methods, such as Proportional Derivative controllers. The quadrotor prototype should
also be taken to an outside environment to see its performance tested under more extreme
conditions.
BIBLIOGRAPGHY
[72]

[1] URL: http://en.wikipedia.org
[2] URL: http://3dgameprogramming.net
[3] URL: http://aviastar.org
[4] URL: http://draganfly.com
[5] URL: http://mikrokopter.de
[6] URL: http://www.q4systems.de
[7] URL: http://blogspot.com
[8] URL: http://microcontroller.com
[9] URL: http://pics.towerhobbies.com
[10] URL: http://hobbycity.com
[11] URL: http://xoarintl.com
[12] URL: http://youtube.com
[13] IDG500 Datasheet from URL: http://invensense.com
[14] ADXL335 Datasheet from URL: http://analog.com
[15] http://sparkfun.comhttp://shop.graupner.dehttp://arduino.cc
[73]

Main Project - FINAL COPY 786

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