Uav Design For Security Monitoring

International Journal of Emerging

Technology & ResearchVolume 2, Issue 2, Mar - April, 2015

© Copyright reserved by IJETR (Impact Factor: 0.997)

Uav Design For Security Monitoring

ONONIWUG. C., ONOJO O. J., CHUKWUCHEKWA N

Dept. of Electrical/Electronic Engineering,Federal University of Technology, Owerri,

Abstract— This work presents the design and construction

of an unmanned aerial vehicle (UAV), to be used as an

autonomous guided security system for civilian

applications in areas such as surveillance and

gathering. The UAV was designed to be powered by a DC

battery and to carry a maximum payload of 1.9kg. It is

equipped with a microcontroller, actuators and sensors

which enable it acquire information from its environment,

respond to sensory inputs and move accordingly

desired destination. The hexacopter when tested after its

construction met some of its design specifications such as

weight, communication, correct calibration of motors,

imaging. All the objectives for stable flight wer

achieved due to the difficulty in implementing a

controller to balance the system. More work

in this area to improve on the PID controller in other to

achieve stable flight.

Keywords—aerial, autonomous, hexacopter, s

Unmanned, vehicle.

I. INTRODUCTION

Unmanned Aerial Vehicles (UAVs) are remotely piloted

aircrafts which can be used for many applications where it

may be inconvenient, dangerous, or expensiveto make use of

manned flights. Their areas of application range fr

and rescue operations, firefighting, law enforcement, military,

and news reporting.Generally, the vehicle will have a set

of sensors to observe its environment, and

autonomously make decisions about its behaviour

information to a human operator at a different location

control purposes.

Primarily, UAVs serve as information gathering platform

When compared to manned aircrafts, they result in

in the need for human operators, and conseque

costs and risk. Additionally, because surveillance

requires monitoring for long durations, fatigue may limi

ability of human beings to maintain a high level of vigilance.

UAVs do not suffer from such fatigue. They also offer added

advantages for information acquisition where ground

International Journal of Emerging

Technology & Research (www.ijetr.org) ISSN (E): 2347-5900 ISSN (P): 2347

(Impact Factor: 0.997)

Uav Design For Security Monitoring

G. C., ONOJO O. J., CHUKWUCHEKWA N., ISU G. O


Imo State, Nigeria.

This work presents the design and construction

to be used as an

autonomous guided security system for civilian

and information

The UAV was designed to be powered by a DC

aximum payload of 1.9kg. It is

equipped with a microcontroller, actuators and sensors,

it acquire information from its environment,

ry inputs and move accordingly to a

desired destination. The hexacopter when tested after its

specifications such as

weight, communication, correct calibration of motors,

All the objectives for stable flight were not

to the difficulty in implementing a PID

controller to balance the system. More work will be done

PID controller in other to

, surveillance,

are remotely piloted

aircrafts which can be used for many applications where it

be inconvenient, dangerous, or expensiveto make use of

Their areas of application range from search

w enforcement, military,

Generally, the vehicle will have a set

to observe its environment, and could

behaviour or pass the

information to a human operator at a different location for

gathering platforms.

ts, they result in a decrease

need for human operators, and consequently lowers

. Additionally, because surveillance often

, fatigue may limit the

to maintain a high level of vigilance.

UAVs do not suffer from such fatigue. They also offer added

vantages for information acquisition where ground-based

access is deemed too hazardous (in the case of a crisis or

disaster).

In addition to the advantages stated above, UAV surveillance

often occurs without the knowledge of the

organization being monitored. This is particularly helpful if

they are being monitored for suspicious reasons. Due to the

heights at which UAVs can fly, they are oft

range of sight of people. In addition, they can also be designed

to be very small and maneuverable

detection. As a result of these, UAV

purpose of intelligent security gathering.

The objective of this work is todesign and implement

hexacopter (a six-rotor UAV) with position control using

sensors, which can aid in law enforcement and disaster/c

control by harnessing the advantages of a UAV over a manned

aircraft.

This work is limited to the design of the software and the

hardware aspects of the hexacopter. The hexcopter

designed to carry its own weight and a maximum payload

1.9kg. A microcontroller serves as its processing unit, while a

personal computer (laptop) is used to send control signals

through a desktop application. The design will

alternative sources of power for the hexacopter, except by

using a DC battery. The design covers

(RF) means of sending control signals from the PC t

microcontroller. It includes the calibration of the electronic

speed controllers to read pulse width modulation signals from

the microcontroller.

II. REVIEW OF RELATED WORK

UAVs have experienced a rapid development in the recent

past. Some years back, only few people knew what a

quadcopter was, but now they seem to be everywhere.

happened is a classical case of an enabling technology being

driven by the consumer market.

Bouabdallah, recent progress in sensor technology, data

processing and integrated actuators has made the development

of miniature monitoring robots fully possible

For the hobbyists, theirs are generally simple multirotor

systems, usually quadcopters, designed for fun flying and

hovering, and in some cases are usually equipped with

5900 ISSN (P): 2347-6079

16

., ISU G. O


access is deemed too hazardous (in the case of a crisis or

In addition to the advantages stated above, UAV surveillance

knowledge of the people or

being monitored. This is particularly helpful if

they are being monitored for suspicious reasons. Due to the

heights at which UAVs can fly, they are often beyond the

people. In addition, they can also be designed

euverable thereby evading radar

detection. As a result of these, UAVs are well suited for the

purpose of intelligent security gathering.

The objective of this work is todesign and implement a

rotor UAV) with position control using

which can aid in law enforcement and disaster/crisis

the advantages of a UAV over a manned

to the design of the software and the

hardware aspects of the hexacopter. The hexcopter will be

designed to carry its own weight and a maximum payload

s its processing unit, while a

(laptop) is used to send control signals

top application. The design will not cover

of power for the hexacopter, except by

a DC battery. The design covers only wired and wireless

(RF) means of sending control signals from the PC to the

the calibration of the electronic

pulse width modulation signals from

OF RELATED WORK

UAVs have experienced a rapid development in the recent

Some years back, only few people knew what a

but now they seem to be everywhere. What

happened is a classical case of an enabling technology being

driven by the consumer market. According to Samir

Bouabdallah, recent progress in sensor technology, data

processing and integrated actuators has made the development

possible [1].

For the hobbyists, theirs are generally simple multirotor

systems, usually quadcopters, designed for fun flying and

hovering, and in some cases are usually equipped with

International Journal of Emerging Technology & Research

Volume 2, Issue 1, Mar - April, 2015 (www.ijetr.org) ISSN (E): 2347-5900 ISSN (P): 2347-6079

© Copyright reserved by IJETR (Impact Factor: 0.997) 17

onboard cameras for aerial photography and heavy lifting. The

earliest example of such designs was developed in 1921 by De

Bothezat. Several models were created e.g. the Mesicopter[2].

A lot of improvements have been made to these early models.

Improvements in terms of the frame, motor dynamics and

control. One such example is the system modeled in [3]. It

incorporated an airframe, improved motor dynamics and

gyroscopic effects. The rigid body dynamics were separated

from the motor dynamics. Stabilization of the UAV has been

further improved in [4] by the proposed inclusion of a simple

controller for attitude stabilization. It has been shown that this

controller can provide the UAV with adequate stabilization.

An experimental platform called the X4 – Flyer quadrotor was

proposed in [5] while the authors of [1] came up with the

UAV OS4 after modeling part of the indoor control with

angular orientation.

The ATLAS ia an autonomous multi-rotor project by a project

group of four avid hobbyists. ATLAS is a quadcopter that is

designed to carry an item from one place to another all by

itself. It was equipped with an autopilot (a microcontroller),

live video feed (with the aid of an onboard camera), and an

array of sensors. The goal of the project was to create a

platform that is able to accurately carry and drop off items

without the need for one to fly it. By clicking on somewhere

on Google maps (within its flying range), it would deliver an

item and return back. More work is however being done to

improve the system [6].

Verbeke et al carried out a research on the design,

construction and flight testing of a rotary UAV for inspection

of orchards and vineyards. The unmanned aircraft was

designed to autonomously fly in between tree rows and use

sideward looking cameras for inspection instead of flying over

the orchard like other UAVs do. The main application was for

harvest yield estimation [7].

There are also NTVU UAVs developed by a team of students

led by Mr. Wang Dao-Yu. The first UAVs developed were

two quadcopters, Blue Feather 1 and 2 intended for aerial

photography. NTVU hexacopter was the second UAV

developed by the team. It was successfully used to provide

aerial photos for a hospital redevelopment project. It had the

following specifications:

a. Ceiling: 1.5km

b. Endurance: 20 - 40 minutes

c. Remote control radius: 1.2km

d. Payload: 3.5kg.

A similar engineering project is a surveillance UAV done by

Andrew Gallagher and Steven Guayaquil [8]. They designed

an autonomous quadcopter with a Raspberry Pi

microcontroller, two cameras, a wireless transmission system

(with the use of a router), a GPS and IMU sensors. Its

limitations include the absence of additional subsystems such

as sensors to detect and avoid obstacles that could damage the

robot, and a digital compass, so that its direction can be

ascertained and corrected.

Our hexcopter will be controlled using the XBee wireless

radio communication instead of the internet wireless

communication technique used in some of the cited works.

Also, we make use of the Arduino microcontroller because

Arduino is a more flexible microcontroller which has a large

amount of pins for different functionalities, whereas the

Raspberry Pi just focuses on graphic interfaces and cameras.

III. METHODOLOGY

The objective of the design is to develop a UAV in the form of

a hexacopter, which can be used for remote monitoring. The

hexacopter will make use of ultrasonic sensors for obstacle

avoidance and PIR sensors for motion detection. It will also be

able to navigate through space using a GPS module and in

terms of control, an RF module connected to a computer front-

end will be used. Several factors will be put into consideration

when preparing the design of the system. These include cost,

weight, power efficiency, reliability, and ease of use.

A. DESIGN SPECIFICATION

The design was carried out with the following specifications.

Lifting thrust: 8.5N.

Weight: Max. Payload: 1.9kg

Max. Weight (without payload): 900g

Total weight: 2.8kg

Battery: Type of cells – LiPo cells (4S).

Estimated flight time – 15mins.

Visibility: Suitable in clear weather only.

Range of radio frequency coverage: 1km.

Frequency of video feed transmission: 5.8GHz.

Frequency of control signals: 900MHz.

B. WEIGHT

Before choosing a motor for the design, the total estimated

weight of the UAV was determined, and then the thrust

required to lift the hexacopter was worked out. This is

necessary because if the thrust provided by the motors are too

little, the hexacopter will not respond well to control and will

even have difficulties taking off. Also, if the thrust is too

much, it might be too agile and hard to control.

A rule of thumb required for thrust is given as:-

Thrust = (weight x 2) ÷ 6

(For 2:1 thrust / weight ratio)

Where: weight = estimated weight of loaded vehicle which is

obtained by addingthe individual weights of all motors,

propellers, Electronic Speed Controllers (ESCs), camera etc.




Table 3.1: List of the components with their respective weight

estimates.

Total weight= 2255g

(Assuming all other components are relatively weightless).

For the hexacopter to hover, it has to beat gravity. Since the

overall weight of the system is 2255g, its 6 motors/propellers

have to produce at least 2255g of thrust in order to beat

gravity. As we have 6 motors, each one has to produce 2255 ÷

6 = 375.83g of thrust (with assumptions that all

motors/propellers produce equal thrust).

Since it is a general rule to have a 2:1 thrust/weight ratio for a

standard hexacopter, the standard thrust therefore required for

each motor is 375.83g x 2 = 751.66g.

From the above estimate for the thrust, an A2830 Out Runner

brushless motor with specifications given in Table 3.2 was

chosen.

Table 3.2: Specifications of A2830 Out Runner Brushless

Motor.

Model A2830-12

Volts 7.4 - 15v

KV(rpm/v) 850

Max. pull 880g

Weight 52g

Max. power 200Watts

ESC 30A

Battery / Prop Lipox2 /11x7

Lipox4 /8x6

Given the equation for static thrust:

T = {(eta x p)� x 2�� x rho}�.�� -----------------------------(1)

Where: t = thrust

eta = propeller hover efficiency (typically 0.7 - 0.8)

p = shaft power = voltage x current x motor efficiency (in

watts)

r = propeller radius (in meters)

rho = air density = 1.22kg/�

The following assumptions were made:

• eta = 0.7

• motor efficiency = 50% (the maximum

efficiency for a brushless motor is around 75%

and happens around 90% of the motors

maximum speed).

• propeller radius = 1/2 the length of the

propeller ( given a 10 x 4.7 propeller) = 5 inches

= 0.127m

• current and voltage (for shaft power) =

maximum current and voltage of the motor

whose products gives the maximum power =

200W.

The estimated thrust for one motor therefore becomes:-

T = {(0.70 x 200 x 0.5)�x 2 x 3.142 x 0.127� x 1.22}�.�� T = 8.4597N = 8.4597 x (1000 ÷ 9.81)g = 862.35g

This value of thrust obtained by calculation based on

estimation can be said to be close to the value of the thrust

(max. pull) of 880g as specified by the manufacturers.

Therefore the choice of motor is justified.

In choosing ESCs for the motors, the amperage of the motors

was put into consideration. For example, the selected motor

draws a maximum of 13.15A current. So it was necessary to

go for a speed controller with amperage higher than 13.51A.

A 20A speed controller with battery eliminated circuit (BEC)

output of 5V/2A was chosen. This means that 5V output from

the ESC can power up the the microcontroller and the

servomotor (for camera gimbal). With this, the ESC can

comfortably handle the most amperage that the motor will

ever draw; and together with the suitable battery pack, the

motors will always be able to pull all the energy it needs and

so will be able to realise its full potential.In combination with

the above motors and speed controllers, a 10 x 4.7 propeller

was selected as well.

C. BATTERY POWER

In choosing a battery, it is usually ideal that the amperage of

the battery pack should exceed that of the motor. This ensures

that even when the motor is running at 100%, the battery will

not hold it back. Therefore to have optimum power/weight

combination, a battery pack just above the motors amperage

should be chosen.

The motor’s amperage is calculated as follows:-

Maximum power of motor = 200W.

Battery voltage (4s Li-Po) = 4 x 3.7V = 14.8V

(where 3.7V is the nominal voltage for each cell).

Maximum motor amperage = 200W / 14.8V = 13.51A (for one

motor).

For 6 motors => 13.51A x 6 = 81.06A

A battery pack with amperage rating above 81.06A is

therefore needed.

For a 4 cell Li-Po battery pack chosen with the following

specifications:

Battery’s milli-amp rating = 6000mAh (where 1000mA = 1A).

Discharge voltage = 35C.

Battery voltage (4s) = 4 cells x 3.7V = 14.8V,

The amperage is given by:

Components Weight

per unit

Number Total

Weight

Brushless

Motors

62g 6 372g

Propellers 30g 6 180g

Sony Camera

& Battery

74g 1 74g

LiPo Cells 680g 1 680g

Servos 44g 2 88g

Frame 530g 1 530g

ESCs 21g 6 126g

Power

Distribution

Board

55g 1 55g

GPS Receiver Negligible - -

IMU Module Negligible - -




Battery ampere rating = (6000mAh x 35C) ÷ 1000mA = 210A.

The amperage of the battery well exceeds that of the six

motors and so is very suitable for the design. There is a

relationship between the vehicle weight and battery run time.

With this, the estimate flight time of the hexacopter can be

determined.

Firstly, the power required to produce the estimate thrust of

751.66g is determined. Since the motor’s maximum power of

200W produces a thrust of 880g, then the 751.66g thrust will

be produced by:

751.66 (200 /880)W = 170.83W power.

With the required power, the current drawn from each motor

can then be calculated:

I = P /U ----------------------------------------------------------- (2)

Where: I = motor current (A)

P = motor power (W)

U = battery voltage (V)

Since 4s LiPo cells with nominal voltage of 14.8V are being

used, required current is 170.83 /14.8 = 11.54A (for one

motor).

For 6 motors => 11.54A x 6 = 69.26A.

This is the current that the six motors will draw in order to

hover the hexacopter. Since the battery capacity and current

consumption are known, the length of time the hexacopter can

draw that amount of current from the battery can be calculated

using equation 3.

T = (C /I) x 60 ----------------------------------------------------- (3)

T= time (min)

C = battery capacity (Ah)

I = current (A)

T= (6.000 / 69.26) x 60 = 5.2 mins

So the hexacopter should be able to hover for about 5mins.

The actual flight time might vary as this is only an estimate.

D. AUTOMATION The hexacopter navigates autonomously by using a GPS

receiver together with a compass sensor to detect accurately

the UAV’s position in space, its height above sea level and its

bearing from target location.This is achieved by implementing

a GPS waypoint navigation algorithm that receives as input

GPS location and compass bearing signals and then directs the

hexacopter to the desired location.

Table 3.3: List of the Automation Components.

1 Microcontroller (Arduino Mega)

2 Laptop and Intelligent RF laptop module

3 Image capture device (Camera)

4 GPS Receiver

5 Communication System

6 Compass

The Microcontroller Unit

The Arduino Mega is the primary flight controller. It is a small

computer running on an 8-bit AT Mega 1280 system at a

frequency of 16MHz with an 8KB of RAM. The block

diagram in Fig. below shows the input/output relationship of

all other components to the microcontroller.

Fig 3.1: Block diagram showing the input/output relationship of other

components to the flight controller.

Laptop and Intelligent RF laptop module:- This consists of the components required to manually control

the mode of operation of the hexacopter and also convert the

analog video feed into a digital format to be viewed via the

laptop or any digital device for storage. They include an RF

transceiver, microcontroller (Arduino Uno), FPV receiver, an

EasyCap video converter and a laptop with the desktop control

application installed.

Image capture device:- The image capture device is the FPV camera. It has a

resolution of 5mega pixels and is capable of capturing HD

videos. It is connected to a 5.8GHz transmitter which

transmits wirelessly to a 5.8GHz receiver, and then to the

AC/DC converter. A block diagram of the entire unit is

presented in Fig 3.2.

Fig 3.2: Block diagram showing the image capture sub-unit.

GPS Receiver

The GPS receiver sensor has a frequency of 5Hz. It is capable

of updating and acquiring a GPS position fix within 10

seconds. The GPS does not include any device or software

therefore any interfacing will be done from scratch. The GPS

sensor was used together with the compass for correct position

Arduino Mega

(Flight controller)

Sensors GPS/IMU

X-Bee ESCs

Accelerometer Servos

X-Bee Trans

Motors

Arduino Uno Laptop/Control

station

FPV TX Camera

FPV RX AC/DC

Converter

Laptop/Control

station




assertion. The block diagram of the GPS and Compass sensor

unit is presented in Fig 3.3.

Fig 3.3: Block diagram showing the GPS and Compass

sensors unit.

Communication System

A laptop is used as the primary input device to interact with

the hexacopter through a desktop application. The RF device

(X-Bee module) is used to transmit radio frequency

information/data both to the UAV and the control station

(laptop).

E. SYSTEM BLOCK DIAGRAM A simplified block diagram of the hexacopter is shown in Fig.

3.4 below. It shows the functional relationships between all

the components that make up the UAV.

Wireless Communication

Wired Communication

All of these sensors send a lot of data to the microcontroller,

which must process the information according to an algorithm

and prompt the appropriate subsystems for action. An

especially complex task assigned to the microcontroller is to

maintain level flight by varying the speed of individual motors

based upon calculation of data received from the IMU. The

subsystems of the hexacopter are independent, linked by the

microcontroller, the physical frame and the power system. The

frame is designed to be rigid enough to support all the other

systems, yet light enough so as to prolong flight durations to

within designed levels.

The hexacopter has a robust sensor suite which enables it to

operate in more autonomous mode. The autonomous mode

includes subsystems such as a GPS receiver so that once the

hexacopter is given a GPS target location, it can make its own

way to the target coordinates without further human control.

This flight mode requires additional subsystems such as

ultrasonic sensors, so that the robot can detect and avoid

obstacles, and a digital compass, so that its direction can be

ascertained and corrected.

GPS Module Satellite

Microcontroller Compass module

Motor

Fig 3.4: Simplified Block Diagram of the Hexacopter.

Ultrasonic sensors

IMU

Arduino

Mega

GPS

Motors/Props

Camera

ESCs

Radio Comm

.

FPV TX

Control Laptop

LIPO

Cells

HEXACOPTER

FPV RX EASY

CAP




F. POWER DISTRIBUTION

The power distribution of the system is divided into two

sections:

• Power supply for control and automation.

• Power supply for video and image

processing.

Fig. 3.9 shows the block diagram of the power supply for the

control and automation unit.

Fig 3.9: Power Supply for Control and Automation.

The battery is a LiPo 4S pack which has an output voltage of

14.8V and a capacity of 6600mAh. It is connected to a power

distribution board (PDB) which supplies a voltage of 14.8V to

all six ESCs. The electronic speed controllers (ESCs) which

feature a built in battery eliminator circuit (BEC) of

output5V/2A then supplies the 5V which is required to power

the microcontroller.

A separate power supply (two 3S LiPo packs) is used for

image and video processing in order to increase the flight time

of the UAV. Fig. 3.11 below shows the block diagram of the

video/image power supply.

Fig 3.11: Video/Image Power Supply.

One of the batteries powers the FPV transmitter and the servo

for the gimbal, and the camera is powered by the FPV

transmitter. The second battery powers the FPV receiver.

Image/Video Capture

The image/video capture device (camera) is held in place by

the gimbal. It isolates the movement of the frame from the

camera, always keeping the camera leveled at all times. This is

accomplished by moving the camera platform using a servo

motor that is constantly being adjusted by the angular

interpretation of the gimbal.

To move forward or backwards the UAV adjusts its pitch,

whereas to move left or right it adjusts its roll. These flight

characteristics present a big challenge when the camera is

mounted on the UAV frame. Fig. 3.12 shows that the camera

losses sight of an object when the UAV tilts to its right or left.

Hence for autonomous tracking, a fixed camera mounted on

the UAV frame is not acceptable. Instead, a gimbal with a

servo is used to ensure the camera will not be affected by any

change in the UAV altitude.

Fig 3.12: Image/Video Capture from i. UAV top and ii.

Gimbal.

Communication System

The laptop serves as the main input for control signals and the

signals are transmitted to the microcontroller and vice versa

through the use of the XBee RF modules that have been

configured to communicate with one another. An intelligent

RF laptop module was also designed to be used with the

control laptop.

IV. SIMULATION

The Hexacopter design was simulated using Blender

Simulation Software, an open-source 3D software product

whose features include 3D modeling and simulation. On the

other hand, the flow of control signals was simulated using

Proteus ISIS.

A. Simulation using Blender

TO MICROCONTROLLER

BATTERY FPV

TRANSMITTER

CAMERA

SERVO FOR THE

GIMBAL

ii. Object visible from a gimbali. Object not visible from UAV

BATTERY POWER

DISTRIBUTION

BOARD

ESCs

with

BECs

Microcontroller Sensors




Using Blender, a model was created using the design

parameters, weights were assigned to the various components.

Using a scripting pane programmed in python, the device was

set to a level above sea level and its reaction to free fall was

observed. Two observations were made:

• It was observed that model was stable with its

weight concentrated at the centre, with the

weight of the arms balancing it out.

• It was also observed that a rigid landing gear

was more suitable than that made of a spring

because the effect of the spring resulted in

some instability to the system while landing.

Project Model in the Simulation Window.

B. Simulating the Flow of Control Signals with

Proteus

The flow of control signals in the system was simulated using

Proteus ISIS. Fig 4.3 presents a snap shot of the Proteus

simulation window.

The Steps Taken to Simulate the Hexacopter System in

Proteus are as follows:

• A new project window was opened in the

Proteus IDE.

• The ATMEGA328 Microcontroller was

selected from the MCU tray in the Tools

bar. (Since the Arduino UNO board works

with the ATMEGA328 chip).

• The Proteus Simulation IDE did not have

brushless motors in its motors tray; so it was

substituted with animated DC motors.

• Various parts needed for thesimulationwere

selected and connected accordingly.

Fig 4.3: The Proteus Simulation Window

The ATMEGA328 board possessed only one pair of serial

communication interface (Tx and Rx), which was a limitation

as three devices had to be connected to communicate through

the serial ports- the accelerometer, the GPS module, and the

Xbee transceiver. To Solve this problem, a software serial

library was implemented to convert other digital ports on the

microcontroller to serial ports.

Fig 4.5: Configuration of the XBee RF Transceivers Using

the XCTU Software.

Fig 4.6: Testing of the Configured XBee RF Modules

Figures 4.5 presents the screen shot of the testing of the XBee

RF modules using the XCTU software application.After

successfully configuring the XBee modules, the connections

were tested to confirm communications. The test showed that

the XBees had been properly set up. Fig 4.6 presents the test

window showing communication going on between the two

wirelessly connected RF transceivers.

The electronic speed controllers (ESCs) were calibrated to

receive inputs at 1000 RPM minimum and 2000 RPM

maximum.To do this, six brushless motors were set up on a

wooden surface to restrict them from vibrating out of place.

Fig. 4.7 below shows the setup of the motors for calibration.




Fig 4.7: Calibrating the Electronic Speed Controllers.

C. Desktop Control Application. The Desktop control application was programmed using

Action Script 3.0 with the Adobe Flash Professional CS6 IDE.

This platform was used to design the graphical user interface

of the desktop control application. Using the IDE timeline and

script window, the application was programmed to access the

serial ports of its host system by camouflaging as a server and

then accessing peripheral components through the system

serial port. Fig 4.9 below shows the Adobe Flash Software

development environment.

Fig 4.9: The Adobe Flash Professional CS6 Development

Platform.

D. Setting Up and Tuning the PID Controllers.

A PID controller was implemented to balance the system

during flight. It takes data measured by the sensors on the

flight controller (gyroscope, accelerometers, etc.) and

compares that against expected values to alter the speed of the

motors to compensate for any differences, thereby,

maintaining balance.

The PID algorithm consists of two PID blocks, one for

controlling the roll and another for controlling the pitch. The

tuning was done through the following steps.

� All the gains – proportional (Kp), integral

(Ki) and derivative (Kd) were set to zero.

� The P gain Kp was increased until the

response to the disturbance was a steady

oscillation.

� The D gain Kd was increased until the

oscillations were eliminated (i.e. it was

critically damped).

� The second and third steps were repeated

until increasing Kd did not stop the

oscillations.

� Kp and Kd were set to the last stable values

� Ki was then increased until it brought us to

the desired setpoint.

Fig 4.11a: System Balancing

Fig 4.11b: System Balancing.

V. Test Results

Several tests were carried out on the prototype to determine its

level of conformation with the set objectives. A systems lift

test proved that lifting was within the design specification.

Also, a test to determine the take-off speed was successful.

A systems balancing test was carried out to test the PID

controllers. During the test, two arm of the hexacopter were




tied to a beam and held in place by a block balance. Four of

the arms were free to move. This was done to restrict the

hexacopter to one degree of freedom at a time (roll or pitch) so

as to easily stabilize itself. This test made it possible to detect

some bugs in the PID codes and this was corrected.

The results of some of the tests have been summarized in table

4.1.

Table 4.1: Summary of results compared with the

specifications.

CONCLUSION

This work has been able to present the design and construction

of an unmanned aerial vehicle (UAV), to be used as an

autonomous guided security system for civilian applications in

areas such as surveillance and information gathering. Most of

the objectives of the design have been met. Tests uncovered

some bugs in the PID controller which have been corrected.

However, a lot still needs to be done in terms of position and

orientation and also with regards to overall system cost.

REFERENCES

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Proceedings. ICRA '04. 2004 IEEE International

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26 April-1 May 2004.

[2] Leishman, J. (2006). Principles of Helicopter

Aerodynamics. Cambridge University Press,

New York.

[3] Hamel, T., Mahony, R., Lozano, R., and

Ostrowski, J., (2002), “Dynamic modeling and

configuration stabilization for an X-4-flyer” in

Proceedings of the 15thIFAC World Congress,

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[4] Erginer, B., and Altug, E., (2007).

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vehicle” in Proceedings of the IEEE Intelligent

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899.

[5] Pounds, P., Mahony, R., and Corke, P.

(2006). “Modelling and control of a quad-rotor

robot” in Proceedings of the Australasian

Conference on Robotics and Automation,

Auckland, New Zealand.

[6] Foster, S. (2004). “ATLAS – An

Autonomous HeavyliftingMulticopter

Project.”KickStarter.Internet:http://www.kickstar

ter.com/projects/404736069/ [Jul. 25, 2014].

[7] Verbeke, J., Hulens, D., Ramon, H.,

Goedemé, T., and De Schutter, J. (2014). The

Design and Construction of a High Endurance

Hexacopter suited for Narrow Corridors. ICUAS.

[8] Gallagher, A., Guayaquil, S.

(2014).“Surveillance UAV.” B. Sc. Thesis,

Worcester Polytechnic Institute, Massachusetts.

Specifications Goals Met? Comment

Weight 2.8kg Met Entire hexacopter

approximately

2.68kg

Payload 1.9kg

Met

Max. thrust of

5.3kg allows for

1.65kg of payload

Imaging 1

streamed

camera

Conditionally No image

streaming with the

hexacopter on air

as stable flight was

not achieved

Landing device Impact

reduction

Conditionally Impact reduction

partially achieved

by 4 landing gears

Communication Control

through

RF

Met Full

communication

with ground

station

Position and

Orientation

GPS,

IMU and

Compass

Met No stable flight for

testing

Uav Design For Security Monitoring

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