Anadolu University

ABSTRACT
Anadolu Suas team that will participate in AUVSI SUAS competition for the first time aims to
fulfill the duties such as automatic flight, navigation, surveillance, real time actionable
intelligence. Hexacopter which performed its design and production is used in competition.
Hexacopter made the mechanical and aerodynamic tests in wind tunnels is equipped with
navigation and imagery features. The 900 MHz frequency band system is used in order to
communicate with the ground control station. Real-time situation, position, location of
hexacopter and other sensor datas can be monitored on the ground control station. Pictures
taken with GoPro camera at least 9 Megapixel resolution are transmitted to the ground control
station with 5.8 GHz frequency band. Imagery task is fulfilled automatically thanks to these
two? camera. Ardupilot Mega flight control card is used as autopilot system. Hexacopter can
manually be controlled with HITEC Aurora 9 controller which communicates at 2.4 GHz
frequency band in every phase of the flight in every phase of stage. In addition, GPS
informations can be transmitted to the ground station with Hitec 2.4 GHz radio telemetry
system in real time. Energy of hexacopter is met with two 7000 MAh, 14.8 V li polymer battery.
Team Lead : Gökhan GÖL
Team Members : Tuna Ayan, Kemal Mert Makinacı, Seçkin Yener, Furkan Üzmez, Gözde
Yaşar, Emrullah Aslankaya, Ezgi Tetik, Diler Öz, Özge Ermak, Cansel Öğretmenoğlu
Team Pilot : Zafer Öznalbant
Faculty Advisor : Dr. Tansu FİLİK
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1. INTRODUCTION
1.1. Mission Requirements Analysis
We expected to be made in the contest task is related to the waypoint navigation and image
recognition. Part of waypoint navigation is made automatically in all phases of flight provide that
taking point as objective. Part of image recognition included search area from the area where
video or image transfer. The purpose that identifies the same characteristic of an unknown
number of targets in search area. These features include target shape, background color,
alphanumeric character, alphanumeric color, orientation and location. Maximum time is given to
perform command of contest is 40 minutes. These commands are doable with all platform that
heavier than air.
Contest commands are firstly analyzed with engineering approach. So Key Performance
Parameters (KPP) is identified. Worked on tasks by teams are divided into four separate groups.
This group included that airframe design, communication, navigation and imagery. Key
Performance Parameters (KPP) chart was prepared, that was used by the team to identify goals
on which further work was to be done once threshold were complete:
Characteristics
Autonomy
Threshold
Waypoint mission
Objective
All phases of flight
Waypoint Tracking
Static Waypoints
Dynamically changeable
waypoints
Transmitting video or image
During all flight
Only detection target
Imagery
Acquisition and visual
identification
Mission Time
Within 40 minutes (imagery
recognition and location done at
the end of competition)
Manual
Autonomous color and shape
recognition, GPS and orientation
mapping.
25 minutes (Imagery,
recognition and location done in
real time in flight).
Automatic and manual
Control
Safety
Manual control in all phases of
flight, Loiter mode in signal
breaking
Manual control in all phases of
flight, Loiter mode in signal
breaking and fail safe, Automatic
landing in getting out of limit of
battery
Table 1. Identify goals on which further work
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1.2. Systems Engineering Approach
Team is divided by 4 four groups as air frame design, communication, navigation, imagery.
Carbon-fiber, fiber-glass and aluminum are selected for used for structure by regard confidence,
lightness and endurance. As a result of tests, the load carrying capacity of aluminum profile
hexacopter was found to be better than the response windy wind values than others in flight.
Communication frequency defined 2.4 GHz for manual control, 900 MHz for system of telemetry,
5.8 GHz for transferring of video. Communications equipment to support safe flight was given to
be selected.
Firstly it is started with fixed-wing aircraft in order to fulfill the competition missions. However
rotary wing aircraft is chosen because of the fact that fruitful results cannot be gotten (figure 1).
The reason for this, speed of fixed-wing aircraft is faster than rotary wing aircraft. Over speed
makes difficult the detection of targets in ground. Additionaly, some problems are seen in fixed
wing aircraft related to navigation. At automatic detection with hexacopter, it can hold its altitude
when it detects target. In this way, you can also achieve all the features of the target. It is
intended that ardupilot communicates with imagery computer as created software is loaded to
ardupilot flight control card. In this way hexacopter will stay loiter mode in the parts of the target
and it is able to take a picture of target. Because of the fact that automatic detection cannot be
done in targeted features in this year, prepared autopilot system constitutes preparation for the
next year.
Figure 1. Hexacopter
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2. Airframe System Design
Hexacopter is defined as unmanned aerial vehicle which is capable of vertical take off and landing,
is capable of hanging on the air, has a high maneuverability, a simple structure, six rotor. Also, it is
an unmanned aerial vehicle with rotary wing which create transportation force via its propeller by
taking advantage of moving force produced by engine.
Air vehicle is designed in a way that distance between motors is 79 cm and height from the
ground is 21 cm. Materials we used in making wings is aluminium and fiber glass in making body.
Aluminium is durable and light at the same time, which is why we used it in making wings. 4s1p
7000 mAh Lipo battery is used in our system. As it is known lipo batteries have bigger capacity of
storing energy in small volumes, which is why they are most used battery type in air vehicles.
Locating body produced according to the modified electronic board, system that prevent
oscillation greatly increases the stability of the vehicle is used. Equilibrium point is set to be in the
center of the vehicle.
2.1. Design Approach
Multicopter systems have not too much type of design. Because there are certain limits.
Hexacopter all equipment's design to ensure proper placement is made. Sensor kits are mounted
to the body vibration inhibitors to protect from vibration. Flight control board is mounted with
anti-vibration to be at the center of the vehicle. The GPS sensor is mounted on the body to be
away from the electronic device. Batteries are placed in the suitable slots that under of body to
ensure that the x-axis under.
Holes were opened to parts on the body strength to some minor to lighten the weight of the
hexacopter. Motor cables are passed through aluminum profiles to protect against shock.
2.2. Manufacturing
The primary is hexacopter is made mainly of carbon fiber. 2 composite body was produced but
the engine thrust levers to reduce the impact has been made thick for strength. Produced single
mold body plus the resistance caused too much vibration. So other hexacopter was manufactured
using aluminum and fiber glass materials. Strength statically tested and it was found that 14 kg of
withstanding loads.
2.3. Power System
With a payload take-off weight of 2.9 kg, hexacopter must be equipped with a power system that
can provide enough thrust to keep the hexacopter aloft for at least 20 minutes with ample
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reserve power for emergency situations. Additionally, gimbal and FPV (flight person view) systems
energy supplied by external battery.
6 pieces Tiger MT2814-10 770 Kv brushless electric motor was used in hexacopter. This engine
was chosen based on its ability to deliver 132 Watts per kg of nominally in cruise, as well as 147
Watts per kg of burst, power reserve. As a result of static tests of motors using 4S 14.8 V battery
with 13 x 47 propeller efficiency was found to be high. Figure 2 is shown in. So 3 CW, 3 CCW 6
pieces of 13 x 47 carbon fiber propellers are used.
12*45 Propeller-Motor Static Test
1500
Thrust
(g)
1000
500
0
0
10
12
13
14,3
14,6
14,9
16
18
20
17,2
19,1
Current (A)
13*47 Propeller-Motor Static Test
1500
Thrust
(g)
1000
500
0
0
9,2
11
12
13,4
13,6
13,9
15,1
Current (A)
Figure 2. Propeller – Motor Static Tests
As a drive brushless motor 50 A electronic speed controller (ESC) is used. It supports high voltage
up to 29.6 V 8S ESC. BEC (battery elimantor circuit) circuit output is 5V/3A thus receiver is
supplied.
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In Hexacopter two units 14.8V 7000mAh 45C 4S batteries are used. Batteries connected in parallel
to each other thanks to this strength times were increased .Power module is used for making
battery voltage control (Figure 3). Power module measures battery voltage and current drawn
and then transmits to Ardupilot flight control board. Also thanks to the voltage regulator that is
on it provides the energy of Ardupilot.
Figure 3. APM Power Module
Lion polymer batteries’ that are used for hexacopter system feeding times are calculated as
follows:



Current capacity = 2*700 =14000 mAh ( it may generate 14 A in 1 hour)
Discharge Coefficient = 45C
In normal state capacity of current generate in 1 hour = 14A*45 = 630A
According to this calculation batteries that are used can supply 630A continuously for 1 hour.
Continuous current values that are drawn by motors are 27 and 6 motors are used.

The current drawn by the motor = 6* 27A =162A
External 3s 1500 mAh Lipo battery is used for Gimbal and FPV (First Person View ) systems. This
battery's voltage and current information is transmitted to the ground control station as a real
time by telemetry system.
2.4. Navigation System
Autopilot flight occurs almost in every missions in the SUAS competition. If it is performed, there
will be positive effect in the scoring. Ardupilot flight control board is used for autopilot system of
hexacopter. This flight control board that has Atmel 2560 processor is open source. For the
competition, autopilot code is improved and all flights during the competition will be aimed with
the autopilot. Waypoints are marked for autopilot over the Google Map in the Ground Control
Station and loaded to the system (Figure 4).
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Figure 4. Mission Planner Drawing Waypoint
There are 3-axis accelerometer sensor, 3-axis Gyroscope, 3-axis compass and barometric pressure
sensor is located on Ardupilot flight control board. The data received from these sensors is
provided through control of hexacopter. In addition to autopilot, flight global positioning system
(GPS) sensor is used. Hexacopter follows coordinates that is loaded to flight control board thanks
to signals that are gotten from GPS. Many waypoints are occurred to scan all search area in
shortest time. There is an example in Figure 5.
Figure 5. Search area waypoint
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2.5. Camera / Gimbal System
2.5.1. Camera Selection
The primary mentions of competition recognize the targets and identify the following
specifications:





background color,
shape,
orientation,
alpha-numeric,
alpha-numeric color.
When we thought these specifications and our hexacopter, our camera requirements has to be
below:




high resolution camera between 100 and 750 ft.,
small size,
lightweight,
take images and video
In the end, we compared GoPro-Black Edition Hero 3, GoPro-White Edition Hero 3 and Canon
600D.
Weight
Image Quality
X4
GoPro Black
Edition
3
Lens Distortion
X4
3
3
4
Weight
X3
4
4
1
Size
X3
4
4
1
Ease of
Interfacing
Cost
X2
3
3
3
X1
3
4
1
57
54
45
Total
GoPro White
Resolution
2
Canon 600D
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Table 2: selection table of cameras
Finally, we decided to use a GoPro Black Edition Hero 3 camera for competition (Figure 6). The
camera stream is fast video stream that is used by the camera operator to control the operation
of the camera gimbal.
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Figure 6. GoPro Black Edition hero 3 camera
2.5.2. Gimbal Frame
After chosen to GoPro Black Edition Hero 3 camera, we determined to use Walkera 2d gimbal
(Figure6). Because this gimbal is specifically designed for our camera, adoping aluminum alloy
CNC frame, brushless motor, high accuracy electronic system. Also, when hexacopter altering the
flight or shaking happened, the camera can still be horizontal and stable. High quality CNC
precision machining, high performance brushless driven, more precise and longer life. Control
range are -45 / 45 roll and – 135 /90 Tilt.2 Dimension gimball is suitable for our system, high
precise and stable frame design to make sure the camera control accurately during high speed
flying. During the flight our camera focuses on targets on the ground. If it is necessary, the gimbal
is controlled manually through a joystick operated from the ground station. Other important thing
is lightness for UAV G –2D gimbal system weight is 120 g.
Figure 7. Gimbal System
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3. Data Link
3.1. Radio Module
Communication between the air vehicle and the ground station is one of the most important parts
of this project. Thanks to telemetry system ground station, user can obtain data about final
situation of air vehicle. Communication between the air vehicle and the ground are provided with
three wireless links. These links are 2.4 GHz radio control transmitter and 5.8 GHz imagery ground
station, the 900 MHz autopilot ground station.

A 900 MHz data link is used by autopilot to communicate telemetry and aircraft
information to the ground station (Figure 8). For 900 MHz data link Xbee Pro 900HP
wireless transceiver module is provided. We used this module because; XBee-PRO 900HP
embedded module provides best-in-class range wireless connectivity to devices. It takes
advantage of the DigiMesh networking protocol, featuring dense network operation and
support for sleeping routers, and is also available in a proprietary point-to-multipoint
configuration. Supporting outdoor RF line-of-sight ranges up to 28 miles with high-gain
antennas and outdoor RF line-of-sight range up to 6 miles (9.6 km) with dipole antenna
and data rates of up to 200 Kbps, the module is ideal for extended-range applications
requiring increased data throughput. The XBee-PRO 900HP requires no programming and
can be configured easily using Digi’s free X-CTU software or via a simplified AT command
set. XBee modules are pre-certified for use in multiple countries, further reducing
development costs and time to market. This modules are easy to use and are available in
a variety of different protocols, enabling users to substitute one XBee for another with
minimal development time and risk. Two Xbee modules are used one of them on UAV and
the other one is on ground station. Using this module Flight informations
(speed,position,angle..etc.) that is about UAV are sent or received by user interface that
in groun station pc and are provided for user. Using this xbee destination points, control
parameters and another flight information is sent to UAV.
Figure 8. Xbee Pro 900HP

A 5.8 GHz data link is used for transmission for video from the camera that is on
aircraft to the image processing software at the ground station. Thanks to 5.8 GHz
power of frequency high quality video transmission is provided. Furthermore, 5.8 GHz
frequency power barriers frequency distortion that is happened due to modems, ADSL,
other electronic devices.
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
A 2.4 GHz data link is used to communicate remote control signals from controller to the
aircraft. When autopilot becomes in out off control, receiver is connected to aircraft using
this data link.
3.2. Antennas
3.2.1. Xbee SMA Connector Antenna
900MHz 5dbi SMA antenna is used to communicate between autopilot and ground station. This
antenna works in the frequency band of 900Mhz. dBi is a representation of relative power on the
other hand this means gain, higher dBi is usually better. According to this comparison we decided
to use 5dbi 900 MHz antenna. Furthermore, this antenna has flexible antenna features a tilt-andswivel SMA connector, allowing them to be used vertically, at a right angle, or any angle inbetween.
Figure 9. SMA Connector Antenna
3.2.2. Cloverleaf Antenna
5.8GHz 9dbi Clover-leaf antenna is used to transmit video to imagery ground station. This antenna
works in the frequency band of 5.8GHz ISM. It can be used in the 5.8GHz wireless video module)
and also other transmitter and receiver working in the frequency band of 5.8GHz. The antenna
has low profile, light weight, high reliability and wide communication range. We made test with
patch antennas that have same frequency but we chose cloverleaf antenna design because it has
one of the best antenna designs for aeromodeling activities, especially the FPV flying. Also it has
the characteristic of wide wave band range and circular polarization to ensure the stable
transmitting and receiving when the aircraft is in any attitude and position. So it can provide
reliable wireless video signals during a flight.
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Figure 10. Cloverleaf antenna
4. Ground Station
In our system, all flight operations are controlled through the ground control station. For
example, we can program the search area, and emergency target coordinates before the takeoff.
The main purpose of the ground station is communication with the unmanned vehicle system.
Ground station consists of a network of computers that are used to process flow of images,
display telemetry datas from received the UAS and detect the target manually.
There will be three computers in the ground station.
One of these computers is used to display telemetry data. Ardupilot 2.6 is used in the system.
Therefore, Mission Planner is using in order to display telemetry data. Mission Planner is a fullfeatured ground station application for the APM open source autopilot project. Mission Planner
can be used as a configuration utility or as a dynamic control supplement for your autonomous
vehicle. It helps us about the vehicle’s motion and situation. Mission planner supplies to display
hexacopter attitude, speed, altitude, location, wind direction and speed, battery voltage,
waypoints which are passed or which will pass, etc...
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Here some of Mission Planner properties:

Point-and-click waypoint entry, using Google Maps.

Select mission commands from drop-down menus

Download mission log files and analyze them

Configure APM settings for your airframe

Interface with a PC flight simulator to create a full hardware-in-the-loop UAV simulator.
Second computer is used to flow of imagery that received from unmanned system. If it is need to
detect target manually, this computer can be used. In this situation print screen button will used.
Third and last computer is used to run image processing algorithms. OpenCV libraries are used for
this purpose. All of the programs are constructed with using OpenCV libraries. OpenCV (Open
Source Computer Vision) is a library of programming functions mainly aimed at realtime computer vision. Received video from the unmanned vehicle is processed in real time.
Targets are detected with using the color properties. Then, this target is cut from the video and
saved in a folder as a jpeg. Finally, another program is executed over these detected targets to
detect other properties.
5. Target Recognition and Analysis
Our target recognition and analysis are based on some operations that on original and refined
images for the purpose of identification of target properties. Our system has two parts. One of
them is on-board system which perceives the target, takes a photo on JPEG format and sends it to
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ground station. The other part is ground station system which analyses the image according to
shape and alphabetic character.
5.1. On-Board System
On-board imaging system is based on recognize different colors from background and take
images. Our real-time algorithm which is written C language with OPENCV tries to detect
according to targets’ colors. First of all, real-time imaging is taken inside of the code. These
imaging are RGB (Red, Green, Blue) format. After that, this format is transformed HSV (Hue,
Saturation, Value) format. Targets’ colors are tried to perceive on images of HSV and our
algorithm do color detection according to our specify color interval. For this reason, we need to
introduce HSV color interval for using every color. Therefore, a color filter is designed. When
doing this, we thought that the targets’ colors are basic colors like red, green, blue and yellow.
Example targets are created these fundamental colors according to SUAS competition rules
specifications and ANADOLU BORAN is tested on these targets. Images are saved from taking
GoPro Black Edition camera. These, which are included targets, are separated for later use. These
frames are transformed from RGB format to HSV format with designed color filter. Pictures of HSV
format have three channels, so those are converted binary format. HSV values, that can change
manually, are varied until target is detected on figures of binary format via designed a simple
interface. When the optimum color intervals are found for every basic color, our real color ranges
are formed. Different ranges of hues, saturations and values have been determined for each basic
color (upper hue, upper saturation, upper value, lower hue, lower saturation, and lower value).
Also, some other morphologic operations (erosion, dilation) are done on images to destroy noises.
Thus, non-target small areas have been prevented.
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Figure 11. Designed interface and operations
Our target recognizing algorithm goes through the same process with the color algorithm. Realtime frames are taken inside of the code and all frames are processed separately in the code.
Again, images of RGB format are converted HSV format in different functions for each color and
those also are transformed binary format according to our HSV range color. As using the
OpenCV’s moment functions, area, which is appropriate for HSV ranges, are calculated number of
pixels. Besides of that, center (x,y) coordinates of area are found as pixel values. If the calculated
pixel amount is in the possible range (the range was calculated by considering the space that
targets will cover in the competition flying height rule), it is thought that the target is in the color
of the function that works in the image. To be sure, if there is really a target in the zone, based on
the center of the zone, a smaller image is obtained by cropping the photo of a wider zone that
covers it. This frame is run in the same function. If enough space in the same color can be
detected, then it is accepted that there is really a target in that photo and saved in a folder.
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Figure 12. Image
5.2. Ground Imagery
5.2.1. Target Recognition
Target recognition duty is realized on ground station via MATLAB. When the target is detected,
camera takes a frame by Panda Board then the image is sent to ground station for the purpose of
processing with Matlab. Actually, processing HD image with matlab is so slow. So many methods
have been tried to make quick processing with matlab.
The target recognition code in Matlab consists of two main parts. First part is binary image
processing part and second part is RGB image processing part. While first part provides
recognition of the shape and alphanumeric, background and alphanumeric colors are specified by
second part.
In the first part, after binary image is obtained, morphological operations are applied for reducing
noises. If the noises are not eliminated, essential object cannot be distinguished from irrelevant
objects, also cannot be labeled. The other purpose of morphological operations is clarifying the
alphanumeric which is destroyed by binarization operation. Morphological operations result is
shown below;
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Figure 13. Original (RGB) Image
Figure 15. Opening Operation
Figure 17.Label 1/shape
Figure 14. Binary Image
Figure 16.Dilation Operation
Figure 18. Label2/Alphanumeric
Binary image is available for labeling operation at the end of the morphological operations.
Labeling operation scans the image pixel by pixel and examines connectivity of them in terms of 4
or 8 neighbourhoods, so categorizes the connected components. Resultant connected
components after labeling operation are shown below;
As a result, shape and alphanumeric are separated from each other so, different algorithms can
be applied for shape and alphanumeric individually. While correlation algorithm is applied for
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recognizing the shape of the target, OCR (Optical Character Recognition) is applied for identifying
the alphanumeric. However, if the object orientation is not corrected, these algorithms cannot
work effectively. So, orientation of the objects must be fixed before applying these processes.
Correlation algorithm is based on matching original image and template image. Correlation
estimations have the values between [0,1]. If the correlation estimation is equal to 1 or greater
than 0.8, similarity can be happened among the matched images matrixes.
In the OCR algorithm, features are extracted from each individual character. This features
extraction operation is required for constitution a statistical model for each character class. The
particular classes that the characters belong to are labeled. Each character class tends to cluster
together. For instance, in the figure below, it can be seen that the 9’s have a mean Orientation of
118 and HPSkewness of 0.035.
In the second part of the program,RGB image is processed for detecting background and
alphanumeric colors. In accordance with this purpose, K-means algorithm is applied to original (RGB)
image.
objects in cluster 1
objects in cluster 2
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5.2.2. Target Recognition Flowchart
6. Flight Safety and Risk Management
Safety is a priority for Anadolu SUAS. The derived risks were based on previous flight test
experiences and listed based from historical research on common UAV flight risk operations. Each
risk was evaluated on its impact to the flight mission and likelihood of the issue to occur.
Potential risks and damaging situations and previous failures discussed. After these discussions,
team indicates risk definitions and according to them team has a risk management plan.
6.1. Flight Safety
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Anadolu SUAS has an autonomous hexacopter. In case of unexpected flight operation failure
system has some specifications. Air vehicle system has a three control modes which are manual,
loiter and auto mode and additionally fail safe mode which is feature of control system. For
appropriate situations, appropriate mode can be select. For instance in autonomous flight
unexpected route changing, manual pilot will select immediately. On the other hand, when
manual pilot controlled the air vehicle, pilot may loss of his/her control then auto-pilot can take
control immediately. In case of loss of communication signal, vehicle engine reduced the throttle
50% and haxacopter stay on the air in Loiter mode. When the battery cell voltage drops below 3,
6 V, hexacopter starts to automatic landing. In the case of battery power loss hexacopter starts to
automatic landing and can be controlled manually. In the case of vehicle loss GPS satellite,
hexacopter stays on the air 30 sec then switchces to Loiter mode and wait control signal from
ground station.
Failure
Hexacopter Response
Battery Power Loss
Hexacopter starts to automatic landing and it
can be controlled manually.
Loss of Communication Link
Hexacopter stays on the air in Loiter Mode until
battary cell voltage drops below 3.6 V. Then it
treats as in the case of Battery Power Loss
failure.
Hexacopter stays on the air 30 sec and switches
to Loiter Mode and it waits control signal from
ground station.
Loss of GPS
Table 3. Risk Management
6.2. Physical Safety





Removable parts and components, safely fastened and secondary fastener attached.
Every cable connections, isolated from environment. When choosing cables, their current
capabilities and heat specifications are noticed. Manufacturer advised original cables have
been used with appropriate lengths.
Cable, antenna, battery and other electrical circuit connections has strength to avoid
splitting from each in case of shaking, vibration and strong wind. And also these
connections have been isolated electrically and also for liquid contact.
In case of fire theam? has two different fire extinguishers which are involve all type of
fires (ABC type) and second extinguisher is especially for electrical fires. On hexacopter
chasis is aliminium so fire risk may occur just because of electricity. Team has knowledge
about how to use fire extinguisher and which extinguisher is used for what kind of fire.
Preflight Go, No-Go checklist to ensure optimum operational status of the hexecopter.
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
Team has a precautions check table.
o Before the every flight operations, dedicated and trained team members checks the
safety precautions.
o During the competition, these members will use check tables to avoid any mistakes
 Team has a some safety practices
o Fire extinguishing
o First aid in case of small injuries
o Handling with explosive and damageable parts on UAV
7. Conclusions
This journal paper has shown that Anadolu SUAS team has a solid understanding of mission
requirements and rules for the 2014 AUVSI Student UAS Competition. Anadolu SUAS team worked
over the past nine months to set up the Anadolu SUAS hexacopter. The system was developed by a
team of ten undergraduates and one graduate students split into team.
Our aims fulfill the duties such as automatic flight, navigation, surveillance, real time actionable
intelligence. Anadolu SUAS team looks forward to the opportunity to prove our abilities to succeed in
the competition.
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