Assembly of a UAV: hardware design of a UAV
Contents
1. 33 HARDWARE ouai 34 PROJECT UNEE GRATION s 35 AES See 36 S CONCLUSIONS as es 38 REFERENCES oid Os Eben a A det idee veda qu ve EI cee 39 APPENDIX 41 APPENDIX RU 43 IV Introduction 1 Introduction 1 1 Background UAVs are aircrafts do not need a pilot to be navigated in the air Remote controlled systems autopilots are used instead of a pilot on board The merit of autonomous flight makes UAVs preferable beside remote controlled ones UAVs have a great potential of using in real life applications such as reconnaissance fire fighting surveillance and many other civilian and military applications For purposes of basic understanding flight dynamics principals are described in 3 dimensional coordinate system see Figure 1 Longitudinal Roll Y Vertical A oral Figure 1 Flight dynamics 2 The centre of gravity of airplane represents the origin of this coordinate system The axes are called lateral longitudinal and vertical which correspond to pitch roll and yaw respectively Following table explains how to control airplane Control in Transmitter Contro2. elevon aileron 1 08 06 0 4 0 2 angle of co pilot sensors 0 0 2 0 4 0 6 0 8 1 Experiments and Results 45deq Figure 20 Analog sensor outputs of co pilot vs angle of rotation When the experiment is performed outside it can be seen that the range of output voltage rises and lies between 0 8 2 2V Once again elevator servo was measured incorrectly due to the imperfectness of measurement system 0 8V corresponds to 45 of sensor rotation angle as 2 2V corresponds to 45 Figure4 Changes in Elevon and Aileron Servo Outputs 2 6x 0 8 0 6 Voltage V 0 4 0 2 45deg 45deg 2 Time ms Figure 21 PWM servo outputs from co pilot s computer in time domain 26 Experiments and Results Aileron and elevator servo reactions are illustrated in figure 21 The pulse width of PWM signal varies between 1 2 and 1 8 with respect to co pilot s rotation angle This pulse is used to control servo arm by changing the width of Concluding the signals coming from co pilot s sensor depend on the environmental factors such as buildings trees etc Also weather conditions affect the co pilot s performance Namely if the weather is rainy or snowy sensitivity of the sensors become more imprecise So it 15 important to consider weather conditions before to perform it 4 2 Understanding the Mi
3. LeJOS allows concurrent programming with the use of threads Thus the autopilot can execute two or more tasks at the same time such as processing the GPS data controlling the NXT Prototype Board etc 19 Hardware Components The installation procedure can be performed as described in Appendix B After the installations steps are followed the programming IDE Eclipse provides an appropriate programming environment that allows creating new LeJOS codes and uploading them into the NXT intelligent brick 2 16 NXT Prototype Board NXT prototype board 23 is a platform developed by HiTechnic which allows someone builds his her own design or communicating with other devices through NXT NXT G prototype programming block see Figure 17 can be imported as presented by manufacturer and use to read 5 analog inputs and read and write 6 digital ports ate sxe s b aiie 5 Figure 17 NXT prototype board connections and NXT G block 23 Since NXT requires communication if it is desired to connect a device which uses analog and digital signals besides C bus which consists of SDA serial data and SCL serial clock signals then this prototype board should be used to provide a suitable interface 20 Methodology 3 Methodology 3 1 Project Steps In order to reach the goal of providing the hardware and the hardware software interface support to the aircraft platform be able to perform
4. Halmstad November 2009 Ugur Bozkurt amp Mustafa Aslan Preface Title Assembly of an Unmanned Aerial Vehicle UAV Authors Ugur Bozkurt amp Mustafa Aslan Degree program Electrical Engineering University Halmstad University Year 2009 Supervisors MSc Edison Pignaton de Freitas Lic D Kristoffer Lidstr m Abstract This bachelor thesis is dedicated to assemble the hardware system of a UAV Unmanned Aerial Vehicle in order to prepare the platform for an autonomous flight in the air for a given path through the pre programmed check points A UAV 15 an aircraft that contains sensors GPS radio system servomechanisms and computers which provide the capability of an autonomous flight without a human pilot in the cockpit A stable flight requires sensing the roll pitch and yaw angles of aircraft Roll and pitch angles were ensured by a sensor system of FMA Direct Company called co pilot flight stabilization system CPD4 which allows controlling ailerons and elevator manually An autopilot is required for steering the aircraft autonomously according the GPS data and the establish waypoints that the airplane have to pass by The GPS gives heading information to the autopilot and this uses the information of the next waypoint to decide which direction to go Hereby an autonomous flight 15 provided In this project a lego mindstorm NXT was used as an autopilot that is product of LEGO Company 1 The output of the autopilot 15 us
5. esit od umano a da 10 259 2 DK A M M 11 24 BRUSHLESS DOC MOTOR 52 ep dessin 12 Zu BRUSHLESS 25 a hentai ES IU 13 20 Sau 13 2d FLIGHT STBILIZATION SYSTEM Lm 14 P M ENCODER 16 DRL NXT SOFTWAR E M dee 18 v S 19 2 9 NXT PROTOTYPER BOARD ris testen tb teet enses escis ee neun tube eu e bobus 20 S METHODOLOGY saran 21 SM NEU ROME CLS TE RS TN ZA 3 2 CO PILOT SENSOR CHARACTERISTICS AND US AGE 55 iore betur beso beta Uo Pea 21 9 9 2 MINDSTORM NA TASAN AUTOPILOT cette 22 S GR UID i tae 23 4 EXPERIMENTS AND RESULTS 24 ZI 3C OSPIEOT MEASUREMENTS ected ad bU emu uv 24 4 2 UNDERSTANDING THE MINDSTORM NXT HARDWARE esee eene rrr nnne sen nnn nnns 27 4 3 PROVIDING AN INTERFACE FROM NXT TO 29 IH QUI TROUBLESHOOTING S E Mota hance es ae ce ctas galas Cea
6. Assembly consists of the following steps Detailed information about most of the steps can be found in user s manual 10 Joining the Wing Panels Tail Installation Landing Gear Installation Aileron Servo Installation Motor and Cowling Installation Rudder and Elevator Servo Installation Radio system receiver and FCS Flight Control System Installation Window and Strut Installation 2 4 Control Throws Using a ruler throws of ailerons elevator and rudder are adjusted to obtain the desired rates by adjusting the positions of pushrods For example following measurements are given in user s manual 10 Ailerons Low Rate 1 2 inch 13mm with 15 Expo Up Down High Rate 3 4 inch 19mm with 25 Expo Up Down Elevator Low Rate 1 2 inch 13mm with 15 Expo Up Down High Rate 7 8 inch 22mm with 25 Expo Up Down Rudder 1 1 2 inch 38mm Left Right Table 3 Measured throws of ailerons elevator and rudder 2 5 Centre of gravity After hardware installation is completed centre of gravity CG of aircraft must be balanced before the first flight Taylorcraft user s manual recommends 60 73mm back from leading edge of the wing for CG location see Figure 5 Hardware Components Figure 5 Centre of gravity of Taylorcraft 10 CG can be changed after first flight according to the user s choice It 15 important to achieve recommended rates not to lose control of aircraft 1n the air 2 6 Radi
7. by processing the data from the co pilot sensor in the control algorithm implemented in the autopilot To achieve this an interface between the co pilot sensor and the autopilot was required 21 Methodology In the project co pilot sensor outputs had been measured with respect to the angle between co pilot sensor unit and the earth surface As the infrared co pilot sensor provides analog signal as a function of angle to the surface this information is manipulated by NXT autopilot in order to control the servos for the autonomously navigation of the UAV This data 15 acquired by the NXT brick via NXT prototype board The manipulated data is them sent to the co pilot computer via the same board The mechanism to manipulate the co pilot sensor data and use the co pilot computer with this data 1s explained in detail in the following of this report 3 3 Mindstorm NXT as an Autopilot Mindstorm NXT so called lego intelligent brick 1s an electronic platform developed and launched by Lego Company 21 and commonly used in robotic applications NXT is very suitable for the beginners and allows learning robotic applications with its easy to use components easily The idea of using NXT in UAVs as an autopilot first came up with Chris Anderson 4 who 15 the founder of Diydrones com He developed 2 UAV autopilot platforms based on NXT One with HiTechnic Prototype Servo Controller manufacturer provided only one as a prototype which both prov
8. considering the centre of gravity of the airplane which must be within the range given in Section 2 2 3 Centre of gravity is very important parameter in order to avoid balance problems during the flight That 15 why the aircraft can only fly when its weight is balanced and the centre of gravity is right place see Section 2 2 3 Otherwise it cannot keep flying smoothly and undesired dangerous conditions may happen To be able to make the airplane well balanced the heavier parts must be located closer to elevator and rudder servos since CG corresponds to this field So the heaviest hardware part mindstorm NXT and the second heaviest component LiPo battery were placed as close as it allows to the elevator and rudder servos Figure 29 shows the complete hardware installation 34 Experiments and Results Figure 29 Hardware installation inside the aircraft model Taylorcraft450 In Figure 29 it 15 possible to notice the importance of the size of the hardware components used in the project There is not much place inside the airplane to install too much additional equipments So the system should be designed considering the airplane model and how much free space it provides For instance looking at the Figure 29 15 possible to see that the Lego Mindstorm NXT covers a great part of the free space inside the airplane Even interfacing the other components with the NXT is not easy because it fits tight to the free space Because
9. for NXT brick see Figure 15 Many blocks are ready to use are available inside the software NXT G allows dragging and dropping blocks over the screen and uploading the software to NXT brick So we can just call it as NXT intelligent brick G LEGO MENS TORS e a L 3 1 5 CMM ee Figure 15 NXT G retail version 18 Hardware Components As an example the figure above shows that whenever a touch sensor is pushed NXT produces sound Touch sensor block sound sensor block and loop block were built by firm So the user just drags the blocks which he she wants to use and drops them over the program properly After NXT is hooked up computer via USB cable or Bluetooth the program can be run and downloaded to NXT brick Here is another example to understand blocks more clearly Figure 16 An example with NXT G blocks Figure 16 illustrates that blocks wired between them With analog and digital I O ports the data can be delivered through the wires Thus more efficient programs can be created according what it is desired to NXT to do 2 15 LeJOS NXJ LeJOS NXJ 15 a firmware that 15 supported by NXT intelligent brick and an extension of Java As it was extended by Java LeJOS is an open source programming environment that consists of specific classes called LeJOS API The use of this API makes it easier to program the NXT intelligent brick
10. pilot sensor NXT PROTOTYPE BOARD AN Al 00000200000 m 2 4 X X Vee CD 65 B 63 B2 B2 B NET JE ASA by Lay Lay balay 6 B B E t R2R NETWORK DAC Figure 27 Connections of NXT prototype board as an interface SENSOR CO PILOT COMPUTER 30 Experiments and Results NXT prototype board takes analog signal from co pilot sensor and gives digital outputs A DAC digital to analog converter is used to change the digital signal to analog signal again as an auxiliary circuit Figure 28 R2R Network R2 2 R1 Figure 28 illustrates a 4 bit digital analog converter which is composed by a R 2R resistance network When an input either high or low voltage is applied through the inputs from 0 to N for N bit DAC the analog output can be observed on the load resistance RL represents the co pilot s internal resistance Finally the co pilot computer can use the analog signals provided to control the aileron servos The NXT can be programmed with the NXT G block which 15 supplied by the manufacturer but also with other software programmed in other languages In this project LeJOS a Java extension for Mindstorm was used to develop the NXT software used to navigation control so the software hardware interface was also developed in this language This interface which allows the high level navigation commands be translated in signals that will control the servos as already presen
11. s getProductID String type s getSensorType String ver s getVersion LCD drawotring id 0 7 Product ID HiTechne LCD drawString type O 1 Sensor type Proto LCD drawstring ver 0 2 Version V1 0 p the function provides I2C communication with HiTechnic Prototype Sensor bufl argument is to manipulate the input value to send to outputs 41 Appendix A byte buf new byte 8 byte bufl new byte 8 byte buf2 new byte 8 byte ctrl new byte 8 s getData 0x42 buf 1 analog input corresponds to upper 8 bits s getData 0x43 bufl 1 analog input corresponds to lower 2 bits buf2 0 byte Math floor buf 0 2 buf1 0 16 24 1 ctrl 0 Ox3F All digital outputs are assigned as outputs s sendDate 0xAE ctrl digital I O control bit sh db getjump it sh 24 LOD drawbLtroing DBEEFIT Q0 buf2 0 10 sS sendData 0x4D buf2 1 try Thread sleep 1000 catch InterruptedException e else if sh 1 LCD drawstring RIGHI 0 6 buf2 0 10 s sendData 0Ox4D buf2 1 try Thread sleep 1000 catch InterruptedException e else if sh 0 LOD drawotring Stralghn U S SsendData 0x4D buf2 1 42 Appendix B Appendix B The following steps describe the instructions to use LeJOS 1 10 11 Install the Java Software Developmen
12. 10 load rpm V 1 030 Figure 8 Nippy Black 1210 103 Brushless and Sensorless DC Motor 14 BLDC motors are more advantageous than brushed motors with the aspects of high efficiency reliability reduced noise longer lifetime eliminated brush erosion and more power Applied power is only limited by heat that can cause harm on magnets Requirement of electronic speed controllers ESCs to drive BLDC motors makes their cost higher while brushed motors can be controlled by simple controllers such as potentiometer 12 Hardware Components 2 10 Brushless ESC Electronic Speed Control Electronic speed control 15 ESC consists of an integrated circuit to drive motor via radio control Latest version of ESC incorporates battery eliminator circuit BEC that removes more battery need In many such ESCs support Li poly and NiMH batteries It 1s important to consider the required ratings before choose a battery At this point which type of battery should be used is another issue to think about JETI model ECO 18 used in this project can be seen from the following figure Figure 9 Brushless ESC JETI model ECO 18 16 ESC takes the signal from throttle channel of receiver and supplies 3 phased AC voltages to motor Polarization of three leads from ESC to motor 15 important to achieve desired rotation of motor An important benefit of ESC for model airplanes is to cut the power of propeller motor when the batte
13. Nippy Black 1210 103 BLDC motor Hilechnic s NAT Solderless Prototype Board servomotor GPS module Sub micro servos Brushless ESC JETI Model ECO 18 Li Poly battery Module cable 12 Servo cables Panel potentiometer Battery 6 LM 41DIP 8 op amp 0 25W 1 1 0K O 25W 1 20 K Tools Propeller amp propeller adapter Felt tipped pen Drill bit 1 5 and 2mm Medium grit sandpaper Cardstock Square Brush set The kit parts included m airplane model Tavlorcraft 450 ARF Wing set w Atlerons Fuselage Tail set Cowlmg Landing gear amp covers Wheel pants Pushrod set Fuselage hatch Window set Wing strut set Hardware Components 2 2 Aircraft Taylorcraft450 ARF used in the project is a hobby aircraft model created by E flite and very suitable for beginners see Figure4 Figure 4 Taylorcraft 450 ARF 9 It is a small type of aircraft and contains internal servo mounts concealed from view Endurance of 12 minutes is provided by 11 1V 3 cell Li Poly battery in the air However Taylorcraft can fly in the winds up to 10 mph In the manual specifications are introduced as in the following table 10 Specifications Wingspan 46 in 1170mm Length 36 in 915mm Wing Area 370 sq in 23 87 sq dm Weight w o Battery 29 31 oz 680 740 Weight w Battery 24 26 oz 820 880 g Table2 Taylorcraft specifications Hardware Components 2 3 Steps for Assembly
14. November 2009 Assembly of a Unmanned Aerial Vehicle UAV Bachelor Thesis 1n Electrical Engineering Ugur Bozkurt amp Mustafa Aslan School of Information Science Computer and Electrical Engineering Halmstad University Assembly of a Unmanned Aerial Vehicle UAV Bachelor Thesis Electrical Engineering School of Information Science Electrical Engineering Halmstad University Box 823 S 301 18 Halmstad Sweden November 2009 Acknowledgement Only those who will risk going too far can possibly find out how far one can T S Eliot This project was performed in CERES laboratory in Halmstad University with two groups one was responsible for the interface with a GPS and for the development of software to navigate the UAV 1n the air and our group was responsible for assembling the hardware system providing interfaces to the system actuators and the autopilot in order to allow the autonomous flight We first would like to thank our supervisors at Halmstad University Edison Pignaton de Freitas and Kristoffer Lidstrom because of their supports and ideas helping us during this process We also thank the other group assigned in the rest of the project for their labour and collaboration Denny A Toazza and Tae Hyun Kim You always guided us with your e mails and meetings from the beginning to the end thank you Kenneth Nilsson Furthermore a special thanks to our families to believe and support us
15. an autonomous flight this project was divided in the following steps 1 Measure the co pilot sensor outputs 2 Study the NXT I O ports 3 Make the interface between co pilot and NXT 4 Usea DAC Digital to Analog Converter circuit with prototype sensor board 5 Develop a software interface to the NXT for I O control 6 Study the airplane dynamics to provide the right output to control the servos via the prototype board 7 Combine this project with the navigation control provided by the other group 8 Make areal flight to test the UAV 3 2 Co pilot Sensor Characteristics and Usage The co pilot mentioned in Section 2 7 15 composed of two units sensing unit infrared sensors and processing unit computer The sensing unit which is called co pilot sensor contains infrared sensors that enable to measure roll and pitch angles and sends the information to the processing unit as analog signals through the 4 wires which correspond to two analog signals Vcc and GND see Figure 25 The UAV can do both yawing and rolling motion with the use of only ailerons The analog output of the co pilot sensor for ailerons is needed to be changed according to the control algorithm implemented in the autopilot The control algorithm requires the information that comes from the co pilot sensor It is necessary because the rolling angle varies by the time and the control algorithm needs to use this data to make a turn Yawing motion can be provided
16. at Under Working Directory click Browse Workspace and select the current project Click the variables under Arguments and select java_type_name Do the same for the other tools used for transferring the code and exploring the files Only create a new configuration for each tool and browse to the bin nxj bat and bin nxjbrowse bat there are no arguments for this tool respectively 43 Appendix B 12 Select Run gt External Tools gt Organize Favorites click Add on the new window and select all three of the LeJOS tools and click OK 44
17. ation points then calculates the heading value which UAV must head to achieve an autonomous flight to the next destination waypoint 3 4 UAV Control With the great potential of using UAVs in many applications which can be dangerous for human beings such as fire fighting reconnaissance war fighting among other the navigation algorithms that provide a smooth autonomous flight gets great importance The waypoints are pre programmed or updated in real time considering the task of the UAV and the area where the flight would be performed while the current position is provided by GPS module This project uses only pre programmed waypoints The dynamics of the UAV is composed of the aileron the elevator and the rudder panels which are needed for controlling of roll pitch and yaw respectively An autonomous flight can be provided by taking the controls over either aileron or rudder servos The UAV 15 navigated in the air with the aid of autopilot Autopilot consists of hardware and software components Hardware is designed in a manner that provides an interface to rudder or ailerons which are used for heading the airplane External circuits can be necessary when the signals differ from the ones that Mindstorm NXT can read and provide such as RC servos need PWM signals to be able to drive it and autopilot may not supply convenient signals for servos In such cases autopilot output signal is common must be converted to PWM signals or any ty
18. ation with respect to difference in infrared signals between earth and in the atmosphere Double side sensors in two directions provide day or night stabilization for both ailerons and elevator see Figure 11 Co pilot allows intervening flight system through receiver at any time and this makes co pilot very advantageous if compared with other flight stabilization systems This feature of this co 14 Hardware Components pilot is achieved by the co pilot computer which takes signals from both receiver and co pilot sensor and translates them for aileron and elevator servos Co Pilot a Cees Direct uM XR I Figure 11 Co pilot flight stabilization system CPD4 of FMA Direct Company 19 Co pilot provides only one output for elevator and one output for aileron while two outputs for ailerons are needed To achieve two outputs for ailerons from one output Y servo harness are used which consists of leads that are connected in parallel see Figure 12 Figure 12 Y Servo Harness 20 Weather conditions affect the co pilot operation and if there are strong winds the co pilot may not provide a good stabilization of the aircraft In such cases the user may want to take the control over at this point co pilot offers one channel more for remote switch thus the user can handle the control of the aircraft 15 Hardware Components Specifications are given as foll
19. d was used to control yawing that does not require additional space in the UAV has the sensitivity of 64 values for yawing and the ailerons were used for yawing through the co pilot computer which provides a channel for switching the autopilot on The UAV presented in this project 1s superior to GeoCrawler2 in these aspects The only feature that represents a plus in the GeoCrawler2 project 1s that it has a gimbal camera to observe the environment which was not provided in this project However a camera can be added to the aircraft platform in a future work e G vent rk 5 Product of METU Middle East Technical University FCS Flight Control System platform was uniquely designed G vent rk provides fully autonomous flight that means takeoffs and landings can be performed autonomously The hardware system does not occupy a big space on board because of that most of the components were designed originally and placed on a single board such as GPS module autopilot flight stabilization system etc Therefore G vent rk 1s very advantageous in all mentioned aspects in relation to Introduction the UAV developed in this project However it 1s important to highlight that in our project only components of the self were used It 15 an advantage 1f compared to system developed from the scratch in G vent rk project Dragon Eye 6 Developed by Naval Research Laboratory and Marine Corps Warfighting Laboratory it has a GPS IMU based
20. ed to control the airplane servos to fly in the desired direction A software and hardware interface was designed to allow the autopilot to receive the data from the co pilot sensor and to transmit data to the co pilot processor which will finally steer the actuator servos Experiments were performed with different parts of the system and the results reported Contents ACKNOWLEDGENLIENT ittis io ERR ARAS EUIS I PREFACE M CONTENTI S 1 TINT RODU CG 1 TRACK GR OUND tet T c 1 SP MINIS cerdo 4 4 LE RELATED etr 5 2 HARDWARE COMPONENTS M tur va aa QR M EVE 7 Zl IST OF THE COMPONENTS USED IN THE PROJECT cue e 7 2227 ARORA ET areae 8 EPS RORA SSE fd E 9 Ds ON TRO THROW S 9 C ENIRE su pte 9 29 RADIO SYSTEM satin stone As 10 295 TRANSMILTER ANDTSBCBIVBR s n i rach
21. eliver the complete UAV system Flight test Limitations In this project the UAV was allowed moving only in 2 dimensions during autonomous flight Takeoff and landing are controlled by remote control Otherwise the autopilot is required to control throttle channel according the data which can be provided by an altitude sensor Namely hardware system gets more complex since NXT ports cannot support PWM signals for Introduction throttle to PWM converter can be used but it increases the cost and complexity of the UAV system 1 4 Related projects UAVs were used firstly in military applications But they can also be used for many different purposes These promising aspects make them very desirable Many projects are available related to unmanned aircrafts Some of them are presented as follows GeoCrawlerl 2 3 and 4 4 Created by Chris Anderson In GeoCrawler2 lego mindstorm NXT was used as an autopilot which controls only rudder servo for navigation as we inspired in this project and IMU based flight stabilization system was used In GeoCrawler2 touch sensor was used for switching between autopilot and remote control and a mechanical connection between autopilot and the rudder servo was provided to control yawing The disadvantages of GeoCrawler2 are that it requires more space in the airplane the turn value is not very sensitive and an extra component was used for switching In this project the NXT Prototype Boar
22. em for UAVs which can guide itself by raw GPS data processed in the autopilot Problems were inevitable while hooking up the hardware parts to each other For instance NXT outputs do not support a direct connection Introduction with the components such as RC servos and co pilot sensor due to incompatibilities of the signals The solutions to such problems are presented in this report 1 2 Thesis Overview The report has been written based on the following titles 1 3 Assembling an aircraft model In this project a Taylorcraft450 model has been used Measurements on hardware platform Co pilot sensor outputs for sub micro servos were measured Experiments on autopilot Autopilot mindstorm NXT as an autopilot was chosen in this project It does not support digital PWM or analog outputs It only allows serial data bus communication So experiments were performed and researched on mindstorm NXT output ports Making an interface between autopilot and co pilot To actuate the sub micro servos with manipulated GPS data an autopilot is required to interact with the co pilot Troubleshooting Problems encountered during the previous steps were Clarified Hardware installation After the problems were resolved the hardware was installed in the aircraft model Combining the projects The autopilot was programmed by the other group responsible for the navigation control The two projects were combined to be able to d
23. ey 2004 14 Dragon Eye Online Available from Bayraktar Mini UAV Online Available from URL Attp www baykarmakina com MiniUAV EMT Aladin Online Available from URL http en wikipedia org wiki Aladin UAV Available from URL http www lineu info blog wp content uploads 2008 09 t craft amp 925 05 E flite Taylorcraft 450 ARF Assembly Manual 2007 Horizon Hobby Inc Spectrum DX61 Radio Programming Guide 2007 Horizon Hobby Inc DX61 radio system AR6200 receiver and accessories Online Available from URL http www hobbyzone com Brushless DC electric motor Online Available from URL Attp en wikipedia org wiki Brushless motor Brushless Motor Nippy Black NB 1210 103 Online Available from URL Attp www uberallmodel cz index php id 12 amp lang en Electronic Speed Control Online Available from URL Attp en wikipedia org wiki Electronic speed control Jeti ECO 18 Online Available from URL Attp www sloughrc com asp default asp itemid P JESBECO 128 Servomechanism Online Available from URL Attp en wikipedia org wiki Rc servo Servos Online Available from URL Attp www 2dogrc com ecommerce os catalog images blue servo 72dpi web jpg Co Pilot Flight Stabilization System Online Available from URL http www fmadirect com detail htm item 1489 amp section 20 39 20 21 22 23 24 25 26 27 28 References Futaba Serv
24. for binding operation that ensures Tx to accept signals sent from only the bounded Rx Tx can recognize different receivers up to 10 models Thus Tx does not confuse with another signals in the same frequency range This operation should be performed before each flight Bind Plug Figure 7 Binding operation 11 11 Hardware Components Bind plug 15 inserted corresponding channel of receiver Then receiver is powered by battery via ESC which provides 5V from the throttle channel Leds on the receiver starts blinking that shows system is ready for binding operation which 15 performed as follows 1 Turn on the transmitter while pulling and holding trainer switch LCD display indicates BINDING 2 After 3 seconds leds on receiver go solid hereby system is connected 3 Removing bind plug the binding operation is completed 2 9 Brushless DC Motor Outrunner Brushless DC motor 13 BLDC 15 an electric motor which operates by DC electric The difference from brushed motors 15 that commutation is controlled electrically instead of mechanical control as in the brushed motors Nippy black 1210 103 model used in the project 15 depicted in the Figure 8 Dimensions 40 2 x48 mm Shaft diameter 4mm Weight 489 Li Paly 2 of M PEE NiMH 8 10 Maximum sustained current 12 A Maximum efficiency 79 Current for efficiency gt 72 579 4 Current for efficiency 9 6V 1 2 Internal resistance 1
25. ides an interface from NXT to RC servos and functions as a mux multiplexer which enables to switch between autopilot and transmitter and one with NXT servomotor connected to RC rudder servo mechanically and NXT touch sensor for switching between autopilot and transmitter In this project two solutions inspired from the projects mentioned above were presented with the use either of the HiTechnic NXT prototype board or of a potentiometer with NXT servomotor With NXT prototype board a Digital to Analog Converter DAC circuit was developed to convert digital signal to analog since the co pilot sensor sends analog signals to its computer However to be able to use the prototype sensor it was required uploading a software programmed in LeJOS to the NXT in order to provide I2C communication with the prototype sensor The LeJOS programming primitives enable among other things to get the product specifications Product ID sensor type and version and data transferring 22 Methodology The second alternative used a potentiometer and NXT servomotor to build the interface between NXT and the co pilot In this case the NXT brick determines how much the NXT servomotor will turn while the NXT servomotor turns the potentiometer which is connected to the co pilot sensor outputs as can be seen in Figure 26 The autopilot takes the information regarding to UAV s current position via GPS and compares with the waypoints pre programmed destin
26. its specific sensors and actuators see Figure 13 Communication with external hardware components are provided by bus which is a multi master serial computer bus that consists of serial data SDA and serial clock SCL 16 Hardware Components Figure 13 Lego Mindstorm NXT and its components 21 NXT has 4 inputs touch sensor sound sensor light sensor ultrasonic sensor and 3 outputs Lego servo motors Hardware schematic is shown in the figure below Bluetooth Bluecore 4 0 Display i UART Bus Sound Main Processor Atmel ARMT Output circuit input circuit Co Processor Atmel AVR Figure 14 Block diagram of NXT hardware 22 17 Hardware Components Technical specifications cited from web page www mindstormlego com e 32 bit ARM7 microcontroller e 256 Kbytes FLASH 64 Kbytes RAM bit AVR microcontroller e 4 Kbytes FLASH 512 Byte RAM e Bluetooth wireless communication Bluetooth Class II V2 0 compliant e USB full speed port 12 Mbit s e 4 input ports 6 wire cable digital platform One port includes a IEC 61158 Type 4 50 170 compliant expansion port for future use 3 output ports 6 wire cable digital platform 100 x 64 pixel LCD graphical display e Loudspeaker 8 kHz sound quality Sound channel with 8 bit resolution and 2 16 KHz sample rate e Power source 6 AA batteries 2 14 NXT G Software NXT G is the block programming software
27. l in Autopilot Control panel Motion Aileron stick Left amp Right Left amp Right sensors Elevator stick Up amp Down Front amp Back sensors Table 1 Controlling the airplane Introduction According to the data presented in Table 1 an airplane can make 6 motions in the air by both manually or autonomously and these motions can be described with three dimensional coordinate system As ailerons were used instead of rudder in the project it 1s important to understand how they work to produce rolling and yawing motions Right Aileron Right Force Fr Left Force FI di Center of Gravity Distance L Left Aileron Distance L Resulting Motion Figure 2 An illustration for the ailerons about how they work 24 The use of ailerons 1s needed to be able to bank an aircraft to produce a rolling motion or yawing motion If the ailerons are moved as in the Figure 2 right panel up and left panel down the resulting force causes the right wing tip to move down and the left wing to move up It causes the aircraft to turn in a direction which 1s opposite to the turn generated by the ailerons In other words in the case of using ailerons instead of rudder to turn the aircraft the yawing motion is called adverse yaw The hardware development for UAVs is mostly based on choosing of the autopilot and the flight stabilization systems that make it possible to control the possible mo
28. navigation system It 15 used for reconnaissance and surveillance The features of Dragon Eye are that fully autonomous operation ability of updating the waypoints during the flight image capturing laptop mapping and long endurance 45 60 minutes In this project the developed UAV is much simpler than the Dragon Eye Bayraktar 7 Product of Turkey s Baykar Machine Inc It 15 designed for short range reconnaissance and surveillance applications It has a day night camera and ground based monitoring system Takeoffs and landings are autonomous as well In case of lost communication it returns home With these features it 15 superior to the one presented in this project EMT Aladin Abbildende Luftgest tzte Aufklarungsdrohne im Nachstbereich 8 Product of Bundeswehr German Army It 15 used for reconnaissance by German Army It has a day and night camera for observing the environment It can fly fully autonomously and has daylight and IR video sensors and ground control station for mapping mission planning and flight controlling These features were not included in the UAV presented in this project yet 2 Hardware Components Hardware Components 2 1 List of the Components used in the Project Adhesives 6 minute epoxy 30 minute epoxy Canopy glue Thin CA 28gr Medium 28gr Threadlock Electronic components Lego Mindstorm Spektrum DX61 transmitter amp ARO200 receiver FMA Direct Co Pilot PN CPD4
29. ndstorm NXT Hardware Mindstorm NXT is an intelligent brick which allows many applications only functioning as master in relation to communication with 4 input ports and 3 output ports that are assigned to communicate with sensors motors and any external devices developed by the manufacturer respectively PINI PIN2 PWM signals for the actuators GND PIN3 Ground signal POWERMA PIN4 4 3 V power supply E Am d PINS PIN6 Inputs that include Schmitt trigger Modular Figure 22 NXT output port 22 P PINI Analog input PIN2 Ground PIN3 Ground PIN4 4 3V PINS Digital I O PIN6 Digital I O DIG IAH Modular Figure 23 NXT input port 22 2 Experiments and Results The figures above 22 and 23 show the schematic details of output and input ports NXT uses 6 wire digital communication interface Input ports have an analog input which allows making both digital and analog sensors And input ports 1 3 have a connection with a RS485 controller to manage bi directional high speed communication for future devices which require communication at higher speed rates D24 TP42 BASES VCC RS485 P1 10 DOA AEA DIGIDIO 10K TPS DEA DIA Figure 24 High speed communication hardware schematic Since communication works as a digital interface for the external devices there are some advantageous aspects of communicating digitally Most importa
30. nt one 1s that in digital devices it 1s possible to handle device name and various parameters such as start up time sensor calibration values etc To achieve this each bit or bits in the bus assigned to handle a parameter 15 interpreted separately As a conclusion NXT uses digital interface for communication with external devices and their names must be included in the NXT Otherwise NXT does not recognize such a device and cannot handle their control For example NXT prototype board was used in the project and an NXT G block was implemented to introduce it to NXT If another programming language is used beside NXT G programmer s code must be included with a few lines concerning the specifications of the device such as name and so on 28 Experiments and Results 4 3 Providing an Interface from NXT to Co pilot As mentioned in Section 2 6 the co pilot sensor module has 4 pins which consist of analog analog2 supply voltage 2 5V and ground respectively Analog provides rolling angle whereas analog2 senses pitching angle ANA GND Figure 25 Schematic of co pilot sensor ports Since yaw rate can be controlled by both rudder servo and aileron servos the aircraft can be guided in air only with aileron servos as well as it is the case in this thesis Co pilot s analog output must be handled and used for yaw control In order to do this the mindstorm takes over the control of ailerons by mani
31. o System 2 7 Transmitter and Receiver Spektrum s DX6i 6 channel radio system 11 see Figure 6 used in this project includes 2 4 GHz AR6200 DSM2 6 channel receivers and supports full range for all types of model aircraft Advantages of spread spectrum RC technology are fast communication between Rx and Tx that provides instantaneous servo response two additional channels on receiver is useful for switching between autopilot and radio system etc However programming interface through the LCD display allows adjusting many features see Table 4 Figure 6 Spektrum s DX6i transmitter AR6200 6 channel receiver and bind plug 12 10 Hardware Components Features 10 model memory Graphic throttle curve Dual and exponential rates Graphic pitch curve Dual aileron flaps V tail Delta P mixes Rudder dual rate Servo reverse Revolution mix Sub trims 2 swash types 1 servo 3 servo Travel adjust Throttle cut Timer Alarm Model copy Trainer mode Servo monitor Gyro adjust Modelmatch Range checking DSM2 DuaLink Technology Table 4 Features of Spectrum s DX61 transmitter 11 Most beneficial aspect of the receiver which consists of two parts main receiver and remote receiver 15 to provide more precision while getting the signal coming from the transmitter 1 even if the main receiver cannot catch the signal the remote receiver can handle it or vice versa 2 8 Bind Plug This item see Figure 7 is required
32. o Y Harness 22ga 12 inch Online Available from URL http www innovstivedesigns com images Fut22 al2Y jpg Lego Mindstorms NXT Online Available from URL Attp news cnet com i ne p 2006 16leggo550x322 ipg Lego Mindstorms NXT Hardware Developer Kit Figure 1 Hardware block diagram of the NXT brick 2006 The LEGO Group NXT Prototype Board Solderable Online Available from URL http www hitechnic com cgi bin commerce cgi preadd actionkkey NPT1050 Ailerons Online Available from URL Attp www grc nasa gov WWW K 12 airplane Images alr gif Download Online Available from URL Attp www lejos org Download Online Available from URL Attp libusb win32 sourceforge net ftdownloads Download Online Available from URL http www eclipse org Maximum Takeoff Weight Online Available from URL Attp en wikipedia org wiki Maximum Takeoff Weight 40 Appendix A Appendix A Prototype sensor class written in NXT LeJOS was given as follows import lejos nxt public class PrototypeSensor extends Thread private static LRDataBridge db private int sh int count 0 I2CSensor s new I2CSensor SensorPort 5S1 public PrototypeSensor LRDataBridge tLBDB I2CPort sensorPort s setAddress byte 0x01 sensorPOort setMode t5 ensorConstants TIPBE DONSPREI MW s sendData 0x4F byte 10 public void run while true db new LRDataBridge public void getSpec String id
33. of the NXT is heaviest component in the system it determines the centre of gravity CG of the UAV So it is important to place it considering the change that its addition represents in the CG position 4 6 Project Integration This project which consists of two parts was carried out by the labour of two groups The project was divided in so that one part was more oriented to the hardware components while the other focused in the software components Each part then was assigned for a group The work was performed by each group separately during a certain period of time but the final phase of the project required a co work of both groups order to integrate the two parts 35 Experiments and Results During this collaborative work two alternatives of interfacing the co pilot with the NXT Mindstorm were tried which were explained and had the related problems described in Section 3 4 First two different programming codes written in NXT G and LeJOS were merged according to a version completely programmed in LeJOS In the case of using NXT prototype board it was not trivial to adapt NXT G code to LeJOS In the other case namely the one using NXT servomotor and a potentiometer to take control over the NXT servo in LeJOS it works fine Before the flight test in order to make sure the system works fine the software was tested on the ground This was a done in order to tune the system in relation to the ratings of servo rota
34. omous level flight takeoff and landing have to be accomplished manually However practical problem during the integration phase made the real flight test unsuccessful due to some problems in the navigation algorithm It was identified that those problems were issued by thread coordination timing issues which were not completely solved by the group responsible for the navigation Tests on the ground were performed walking with the airplane and observing if the commands from the navigation program were correctly transformed in movements of the actuators These tests were enough to show that the control part of the whole work the goal of this thesis was successfully achieved 38 References References 1 10 11 12 13 14 12 16 17 18 19 NXT Technology Overview Online LEGO Group Corporation 1932 Available from URL Attp mindstorms lego com eng Overview default aspx Aeronautics Online 2005 Jul 27 cited 2009 Jul 23 Available from URL Attp virtualskies arc nasa gov aeronautics tutorial motion html Robert Abhishek Jeffrey EQ Hung HV Brittiany W An FPSLIC based UAV Control Platform Virginia Commonwealth University Richmond Virginia 2004 Anderson Original DIY Drones UAV projects Online Available from URL Attp diydrones com profiles blogs original diy drones uav Alemdaroglu N Unmanned Aerial Vehicles Projects Middle East Technical University Ankara Turk
35. ot sensors Figure 18 Analog sensor outputs of co pilot for rolling and pitching 24 Experiments and Results Co pilot sensor outputs can be approximated from the figure above as it varies with angle of the sensor axles to the earth surface linearly Because of that the sensors operate inside imprecisely aileron servo output was diverged from linearity However the effect of the walls to work of co pilot s sensor is as illustrated in Figure 18 It depicts that analog output range of sensor outputs are constricted Figure2 Changes in Elevon and Aileron Servo Outputs 2 0deg 45deg 45deg 0 8 _ S 0 6 O i S 04 4 0 2 _ 0 1 0 1 2 3 4 5 Time ms Figure 19 PWM servo outputs of co pilot s computer module Servo outputs from co pilot s computer were observed with respect to angle of rotation of sensor module and represented in time domain in the figure above Black blue and red lines correspond to 45 0 and 45 respectively However the pulse width of the PWM signal determines the rotation angle of servo arm either in positive direction or negative Maximum range of rotation angle is 180 for a conventional RC servo as used in this project 25 Outside measurements Figure3 Co pilot s analog sensor outputs 2 2 1 8 1 6 1 4 1 2 F analog output voltage Volt 0 8
36. ows as presented by manufacturer 19 Inputs aileron elevator throw and aux for remote switching Outputs pitch elevator roll aileron System weight I oz 28 35 gram Sensor dimensions 1 35 octagonal 0 53 thick Microprocessor 1 30 0 89 x0 60 Power consumption 5 ma 2 13 Autopilot UAVs become popular with many kinds of applications in different areas recently UAVs used for surveillance war fighting fire fighting reconnaissance and similar military and civil applications require complex hardware platforms which include image processing take off landing systems GPS navigation flight stabilization systems autopilot etc All of them are called as flight control system FCS Autopilot is definitely the most important part of FCS which takes the information provided to it and makes a decision about what to do next There are many such autopilot platforms that can be used for UAVs A list of some of these platforms is provided as follows ArduPilot an autopilot based the Arduino open source hardware platform e UAV DevBoard 3 axis IMU based autopilot platform Attopilot an original and commercial autopilot platform e Parallax Basic Stamp based on commercial Parallax development board Lego Mindstorm NXT a commercial so called NXT intelligent brick mostly used in robotic projects NXT can be used as an autopilot as mentioned above and it allows many robotic applications with
37. pe of signals as needed The software part 15 as important as the hardware one Besides the navigation algorithm an interface part has to translate the high level navigation commands to the adequate values to be sent to the actuators 23 Experiments and Results 4 Experiments and Results 4 1 Co pilot Measurements Co pilot is a flight stabilization system as previously mentioned that operates with respect to infrared temperature difference radiated from the earth Co pilot s sensor module sends analog signal to its computer module and aileron and elevator servos are controlled with the signal that is converted to PWM in computer module Angle of servo arm depends on the signal coming from the sensor module that represents the attitude of aircraft in the air So that aircraft 15 intended to be levelled and keep the flight smooth Since co pilot is sensitive to infrared radiation from earth it doesn t provide correct results indoor applications because of that the walls prevent co pilot sensors to sense environment Considering this knowledge measurements were taken inside and outside respectively and following figures were obtained Inside measurements Figure1 Co pilot s analog outputs 1 9 elevon 18 aileron Ta e 1 5 1 5 1 4 analog output voltage Volt 1 3 E 1 2 1 1 1 08 0 6 04 02 0 02 04 06 08 1 45deq angle of co pil
38. presented in Listing 1 enables the NXT to get analog data from co pilot sensor and send to the digital outputs as a data of 6 bits The R 2R resistance network gets the bits from 32 Experiments and Results digital outputs BO B5 on the prototype sensor board and sends as analog signals through the wire which is hooked to input of co pilot computer in Figure 27 4 4 Troubleshooting In this section the problems encountered during the working process are presented and the tried solutions to them are outlined Some of the problems were mounting the propeller motor interfacing to co pilot from NXT and some bugs in the software The following list summarizes the main problems encountered in this project and the adopted solutions gt How to provide a stable mounting for the propeller motor The motor has a round shaped motor mount whereas it must be an X shaped motor mount This specific shape is required because the Taylorcraft450 which was the model airplane platform used in this project allows only X shaped motor mount since the manufacturer provides a mounting surface that can only be used for X shaped models The way to solve this interface problem was to screw the motor mount on the mounting surface of airplane providing a tough assemble gt Manipulate the co pilot s signal for steering with aileron servos is it possible The airplane needs to GPS data to be able to determine its current position and a na
39. pulating the data coming from analogl output This is possible by the process described in following This thesis project introduces 2 ways for mindstorm NXT to take over the control of the signal passing through the analog port They are as listed below e By using a potentiometer and an NXT servomotor A potentiometer is to change the voltage coming from analogl and an NXT servo motor which takes the control over potentiometer is used to give reaction according to the GPS data processed in the NXT The connection that makes it possible is presented in Figure 26 29 Experiments and Results Yee HE a perant home rer Figure 26 Interfacing with potentiometer In Figure 26 a potentiometer determines how much the aileron servo arm 15 rotated Bi directional rotation is obtained by wiring potentiometer to Vcc e Byusing NXT prototype board see Section 2 9 NXT prototype board provides communication to NXT as mentioned in Section 2 9 It provides 5 analog inputs 6 digital outputs and various supply voltages 3V AV 5V and 9V The manufacturer supplies a programming block supported by NXT G This block allows taking the control over the I O ports on the NXT prototype board So any other software is required to programme the NXT if this block 15 used Figure 27 illustrates the connection diagram of the interface between the NXT prototype board and co pilot and between the board and the co
40. ry 1s low and keep the controls for ailerons elevator and rudder on Hereby airplane can glide down in safe 2 11 RC Servo RC servos 17 are devices which can be controlled remotely They are employed as actuators in many applications such as steering of a car flaps on model airplane active parts a robot 1 moving the arms and legs etc In this project sub micro servos were used to control ailerons elevator and rudder panels on the airplane see Figure 10 13 Hardware Components Figure 10 Sub Micro RC Servo 18 RC servos include a motor which cooperates with a potentiometer through the gear box PWM signals are translated to achieve desired position from servo arm through the electronic circuit inside it Motor is actuated up to potentiometer attains desired angle from the servo arm RC servos consist of three wires which are for ground supply voltage and PWM signal respectively Angle of servo arm is controlled by PWM signals For example 1 5ms width of a pulse corresponds to 90 and commonly assumed as neutral position for a servo Servo arm can be rotated from 0 to 180 Most servos are employed under the DC voltage of 4 8V 6V and NiCd NiMH or LiPo batteries can be used after provide the correct ratings for servo through ESC or any regulator 2 12 Flight Stabilization System Co pilot 19 is a module composed by a sensor and a computer device The sensor device provides flight stabiliz
41. s a safe way to perform the flight A real flight could not be performed due to bad weather conditions in the final of the project However tests on the ground were performed and they provided good results showing that the commands issued by the navigation program were correctly translated in the actuation of the servos to steer the plane 37 Conclusions 5 Conclusions This thesis reports a hardware system that was designed for a UAV Unmanned Aerial Vehicle which enables the control of the airplane actuators in order to assist the autonomous flight Takeoff and landing systems were not included in the scope of this project All the hardware components used in the project are introduced in the report Off the shelf platforms such as FMA co pilot as a flight stabilization system Lego Mindstorm NXT as an autopilot and Hi Technic NXT prototype board were used While using Mindstorm NXT a problem concerning its I O ports appeared in relation to the interface with the RC servos The design provided in this thesis gives a solution for this 1ssue The navigation software the other part of the whole project was provided by another group This fact required collaboration between the two groups in order to integrate the navigation software with the software interface that control the servo mechanisms Non trivial problems appeared during this integration which were solved given as a final result that the UAV was prepared to make an auton
42. t Kit SDK of Sun Microsystems version 1 5 or later Download the latest version of LeJOS from 25 unzip the contents into a directory and install 1t Create the environmental variables via Start gt Control Panel gt System Click the Advanced tab then Environment Variables Create a new environmental variable by clicking New Type NXJ HOME as variable name and add the LeJOS directory to the path as variable value Download and install the USB drivers from 26 Hold the reset button underside of the NXT brick to delete the current firmware and put it into the firmware upload mode When NXT produces a pulsing sound plug in USB and type nxjflash in the command line After a short time NXT brick will be ready to use Download the eclipse from 27 Unzip the files into a directory and run eclipse exe Create a new project by clicking on File gt New gt Project gt Java Project Type a name for the project and click on Finish Add the LeJOS classes to the Eclipse classpath Select Project gt Properties Click on Java Build Path on the left panel and select Libraries tab Add the classes jar which was located in LeJOS directory as external jars Create the tools for compiling transferring the code and exploring the files For compiler tool select Run gt External Tools gt External Tools Configurations Double click on the Program in the opened window Click on Browse File System under Location and browse to the bin nxjc b
43. ted above 15 detailed in the following 3l Experiments and Results public class PrototypeSensor extends Thread I2CSensor s new I2CSensor SensorPort S1 s setAddress byte 0x01 address is set here getData 0x42 buf 1 analog input corresponds to upper 8 bits getData 0x43 bufl 1 analog input corresponds to lower 2 bits buf2 0 byte Math floor buf 0 2 buf1 0 16 24 1 sendData 0x4E ctrl 1 digital I O control register ctrl 0x3f sendData 0x4D buf2 1 7 digital output 7 Listing 1 PrototypeSensor Source Code The PrototypeSensor constructor shown in line 4 of Listing 1 has to be extended using the I2CSensor constructor from the LeJOS API to be able to use the commands such as getData setData among other established in the API The first action to be done 15 to set the address to 0x01 in line 16 of Listing to be able to communicate with HiTechnic s prototype board The prototype board provides analog inputs that can be handled by reading from 2 registers as 10 bits and 6 bit digital outputs are written via the specific register as shown in lines 53 54 and 56 of Listing 1 Before the data is sent the digital I O ports must be assigned as output This can be achieved writing 0 or bit to the Ox4E register The value for this bit assigns the I O ports as outputs whereas value 0 assigns as inputs as shown in lines 59 and 98 of Listing 1 The code
44. tion which was done by adjusting the servo sensitivity with the aid of the adjust menu in the transmitter The sensors should be checked if they need to be calibrated Then after checking the system tuning the airplane would be ready to fly autonomously 4 7 Flight Test It is time to enjoy Taylorcraft450 s flight With the aid of multi functional DX61 transmitter the model airplane takeoffs and landings can manualy be performed Taylorcraft450 allows many basic aerobatic manuevers with its original design as well as the instructor can To take controls with transmitter over Taylorcraft450 also 15 easy only pushing the sticks on it in the desired direction is enough With LiPo batteries the Taylorcraft450 can keep flying for around 12 minutes The Taylorcraft450 is constrained by the weather conditions e g it can fly in the winds up to 10 mph and the maximum takeoff weight MTOW which is determined taking into account the factors wing flap setting condition of the runway and the weather conditions 28 Landings are easily accomplished with a three point state correponds to wheels in safe In the case of failure of the Taylorcraft450 s Mindstorm NXT autopilot the user can easily take the control over it through the co pilot s computer which enables to control aileron and elevator 36 Experiments and Results servos at any time also the RMT channel from the co pilot computer can gives full control to transmitter This provide
45. tions described above Introduction An autopilot is an electronic platform that controls the aircraft to operate autonomously by the outputs of the software that runs on it In the project the autopilot was assigned to manipulate the data coming from GPS and actuate sub micro servos to be able to navigate the aircraft in the air via pre programmed points waypoints This can be achieved by controlling either aileron or rudder panels However aircraft is levelled by flight stabilization systems sensing the temperature difference between ground and sky According the sensor data ailerons and elevator servos are actuated A fail safe system is required to handle the control when autopilot is failed So hardware system designed with remote control system consists of receiver and transmitter parts The following figure illustrates commonly used UAV hardware architecture which can be used as an overview of the hardware system developed in this work Power supple Batteries bluetooth ommunicatior ailerons amp elevator Rodder to pilot Computer to co pilot Palis Tram miner 6 Channel Radia Heczher Direct Pat Figure 3 An Overview to UAV System Hardware Architecture 3 Figure 3 depicts the hardware system installed in the UAV that provides autonomous flight through the actuators which reacts to infrared sensors and GPS fairly placed in the UAV The following thesis was intended to design a hardware syst
46. vigation calculation done by the NXT to decide which direction to point the heading angle in order to reach the next waypoint Since yaw control can be achieved by aileron servos and co pilot takes the control over the ailerons an interface between the co pilot and NXT must be provided gt What are the possibilities to provide such interface Two ways were introduced and explained in Section 3 3 One is provided by a potentiometer and NXT servomotor and the other is by NXT prototype board 33 Experiments and Results gt What are the constraints in two cases With a potentiometer programming of NXT 15 quite easy to implement It is done by using a NXT servomotor which 15 a specific component of NXT However the NXT servomotor only allows a mechanical interface with the potentiometer which is not very reliable as an electronic interface and requires more space inside the airplane When NXT prototype board is used a problem appears regarding how to program it The manufacturer only offers a program package supported by NXT G A Java extension for NXT called LeJOS was used in this project so it is not possible to explore the manufacturer s program package The NXT 1s programmed to be able to communicate with the HiTechnic s prototype board as described in manufacturer s instructions 23 4 5 Hardware Installation After the all hardware components experienced in laboratory environment they were installed inside the airplane
Download Pdf Manuals
Related Search