AUTOPILOT DESIGN FOR FIXED WING UAV By HUDA ELNIEMA ABD-ELRAHMAN ABD-ALLAH ...

76 Pages·2017·2.83 MB·English

AUTOPILOT DESIGN FOR FIXED WING UAV

By
HUDA ELNIEMA ABD-ELRAHMAN ABD-ALLAH
INDEX NO.124107

Supervisor
Prof. Mustafa Nawari

A REPORT SUBMITTED TO
University of Khartoum
In partial fulfillment for the degree of
B.Sc. (HONS) Electrical and Electronics Engineering
(CONTROL AND INSTRUMANTATION ENGINEERING)
Faculty of Engineering
Department of Electrical and Electronic Engineering
October 2017
DECLARATION OF ORGINALITY

I declare this report entitled “Autopilot design for fixed wing UAV” is
my own work except as cited in references. The report has been not
accepted for any degree and it is not being submitted currently in
candidature for any degree or other reward.
Signature: ____________________
Name: _______________________
Date: ________________________
II
ACKNOWLEDGEMENT

First and foremost, I would like to thank my supervisor prof. Mustafa Nawari,
who has introduced me to the wonders of control theory, and who has guided me
through this project.
I would like to thank Ustaza Azza Algaily for her useful hints and comments.
She is very dedicated to her work with helping students to advance in their studies.
My gratitude goes to Eng. Mohamed Mahdi from Aviation Researches Centre
(ARC) and Ustaza Dania ALSadig from department of Mechanical Engineering, for
their great help during the journey of this project.
I would also like to thank my advisors Dr. Ahmed ELSayed and Dr. Ahmed
Nasr Eldin Ibrahim for their invaluable guidance and support.
Lastly, I would like to thank my best friend and project partner Mohammed
Abd-Elmoneim, I couldn’t do this without him. I am grateful for all the enjoyable
moments and interesting discussions.

III
DEDICATION
This thesis is dedicated with love and affection to my Mother for raising me to
believe that anything is possible. Words cannot describe how lucky I’m to have her in
my life. To my family for their continuous support.
Dedicated to Fedaa Awad, Amira Elhadi, Serien Hashim, Hind Hassan,
Hammam Najeeb, Zahraa Najeeb and Eyas Elhashmi who kept me going, when I
wanted to give up. To my best friends and seniors, whose words of encouragement
and push for tenacity ring in my ears.
To coffee, my companion through many a long night of writing.
IV
ABSTRACT

Unmanned aerial systems have been widely used for variety of military and
civilian applications over the past few years. Some of these applications require
accurate guidance and control. Consequently, Unmanned Aerial Vehicle (UAV)
guidance and control attracted many researchers in both control theory and aerospace
engineering. Fixed wings, as a particular type of UAV, are considered to have one of
the most efficient aerodynamic structures. The focus of this thesis is on control design
for both lateral and longitudinal for a UAV system. The platform understudy is a fixed
wing developed and modeled by University of Minnesota.
The novel approach suggested in this thesis is to use a successive loop closure
to obtain the gains for the PID controller which is implemented in MATLAB Simulink.
The Software in the Loop Simulation (SIL_Sim) is built by adding actuator and sensor
dynamics that can help prove or test the software.
The performance of the designed controller is compared to the controller of
University of Minnesota. It was found that the performance of the designed controller
is satisfactory in term of time analysis characteristics.

V
صلختسملا

ةروصب مدختست رايط نودب تارئاطلا ةمظنأ تحبصأ ةيضاملا ةليلقلا تاونسلا ىدم ىلع
مكحتلا و قيقدلا هيجوتلا بلطتت تاقيبطتلا هذه ضعب .ةيندملا و ةيركسعلا تاقيبطتلا ىف ةعساو
مامتها و راظنأ طحم تحبصأ رايط نودب ةيوجلا تابكرملا نإف كلذل ةجيتن ؛ تارئاطلا هذهل
نم ةدحاو ةتباثلا ةحنجلأا تاذ تارئاطلا ربتعت . ءاضفلا هسدنه و مكحتلا تايرظن ىف نيثحابلا
. ةيكيمانيدوريلأا جذامنلا أفكأ
ةيلوطلا و ةيبناجلا ةكرحلا نم لكل مكحتلا ةمظنأ ميمصت ىلع ةحورطلاا هذه زكرت
و تممص تباث حانج تاذ ةرئاط ةساردلا تحت ةموظنملا وأ ةصنملا .رايط نودب تابكرملل
.اتوسينيم ةعماج ةطساوب تروط
ةيلاتتملا قلاغلإا تاقلح مادختسا ىه ةحورطلأا هذهل ةحرتقملا ةقيرطلا وأ جهنلا
. (Simulink ) بلاتاملا جمانرب مادختساب تذفنو PID لا مكحتم نم بساكم ىلع لوصحلل
ةفاضإ عم Software In Loop (SIL) ةاكاحملا جمانرب مادختساب ةبولطملا ةئيبلا قلخ مت
.جمانربلا رابتخاو تابثإ يف دعاست يتلاو ةيكيناكيملا تلاغشملا و تاساسحلا
مكحتملا ءادأ نأ دجوو . اتوسينيم ةعماج مكحتمب هميمصت مت يذلا مكحتملا ءادأ نروق
.نمزلا ليلحت صئاصخ ىلع ءانب ةيضرم جئاتن ىطعأ دق ةحورطلأا هذه يف حرتقملاو ممصملا

VI
TABLE OF CONTENTS

DECLARATION OF ORGINALITY .............................................................. II
ACKNOWLEDGEMENT ............................................................................... III
DEDICATION ................................................................................................. IV
ABSTRACT ...................................................................................................... V
صلختسملا ............................................................................................................ VI
TABLE OF CONTENTS ............................................................................... VII
LIST OF FIGURES. ......................................................................................... X
LIST OF TABLES. ........................................................................................ XII
LIST OF ABBREVIATIONS ....................................................................... XIII
LIST OF SYMBOLS .................................................................................... XIV
CHAPTER1 INTRODUCTION ..................................................................... 1
1.1 Background .............................................................................................. 1
1.2 Project aim and objectives ....................................................................... 2
CHAPTER2 LITERATURE REVIEW .......................................................... 3
2.1. Coordinate Frames. ........................................................................... 3
2.1.1 The inertial frame Fi. ............................................................................. 4
2.1.2 The vehicle frame Fv. ...................................................................... 4
2.1.3 The vehicle-1 frame Fv1. ................................................................. 4
2.1.4 The vehicle-2 frame Fv2. ................................................................. 5
2.1.5 The body frame Fb. ........................................................................ 6
2.1.6 The stability frame Fs. .................................................................... 7
2.1.7 The wind frame Fw. ........................................................................ 8
2.2 Fixed wing UAV parameters................................................................ 9
2.2.1 Geometric parameters. ................................................................... 9
2.2.2 Basic aerodynamic parameters. ..................................................... 9
2.2.3 Kinematics and dynamics. ............................................................. 10
2.3 Mathematical modeling. ...................................................................... 10
2.3.1. State variables. ............................................................................ 10
2.3.2. Basic aerodynamics. .................................................................... 11
VII
2.3.3 Forces and moments acting on aircraft. ....................................... 13
2.3.4 Gravitational and thrust forces. .................................................... 13
2.3.5 Kinematic equations. .................................................................... 13
2.3.6 Rigid-body Dynamics. ................................................................. 14
2.3.7 Summary of equations of motion. ................................................ 15
2.3.8 UltraStick25-e. ............................................................................. 17
CHAPTER3 AUTOPILOT DESIGN & SIMULATION.............................. 23
3.1 Introduction. ........................................................................................... 23
3.2 Validation of aircraft model linearization. ......................................... 23
3.2.3 Doublet response of the linear and nonlinear longitudinal model.
24
3.2.4 Doublet response of the linear and nonlinear lateral model. ........ 25
3.3 Automatic Flight Control System (AFCS) ......................................... 26
3.3.1 Successive loops approach. .......................................................... 26
3.3.2 Saturation constraints. .................................................................. 27
3.4 Lateral-directional autopilot. .............................................................. 27
3.4.1 Roll Attitude Loop Design. .......................................................... 28
3.4.2 Course hold loop design. .............................................................. 30
3.4.3 Sideslip hold loop design. ............................................................ 32
3.5 Longitudinal directional controller..................................................... 33
3.5.1 Pitch attitude hold......................................................................... 34
3.5.2 Altitude hold using commanded pitch. ........................................... 36
3.5.3 Airspeed hold using commanded pitch. .......................................... 37
3.5.4 Airspeed hold using throttle. ........................................................ 38
3.6 Controller testing. ............................................................................... 38
3.6.1 Software in loop SIL. ................................................................... 38
3.6.2 Comparison. ................................................................................. 38
CHAPTER4 RESULTS & DISCUSSION .................................................... 40
4.1 Introduction ............................................................................................ 40
4.2 Lateral controller results..................................................................... 40
4.2.1 Direction heading controller......................................................... 42
4.2.2 Sideslip doublet response ............................................................. 43
4.3 Longitudinal controller responses. ..................................................... 45
4.3.1 Pitch Attitude Tracker Simulation Tests. ..................................... 45
VIII
4.3.2 Altitude Hold Controller Simulation Tests. ................................. 46
CHAPTER5 CONCLUSION & FUTURE WORK ...................................... 49
5.1 Conclusion ............................................................................................. 49
5.2 Limitations ............................................................................................. 49
5.3 Future Work ........................................................................................... 49
REFERENCES ................................................................................................ 50
APPENDICES ................................................................................................... 1
Appendix A: UAV Nonlinear Simulation Setup ............................................... 1
Appendix B: UAV_NL Model Verification ...................................................... 1
Appendix C: Computing Gains Code ................................................................ 1
Appendix D: Baseline Controller ....................................................................... 1
Appendix E: Heading Controller ....................................................................... 1
Appendix F: UAV Software-in-the-Loop Simulation setup .............................. 1

IX
LIST OF FIGURES.
Figure2-1 Inertial frame ..................................................................................... 4
Figure 2-2 Vehicle-1 frame. ............................................................................... 4
Figure 2-3 Vehicle-2 frame. ............................................................................... 5
Figure 2-4 Body frame. ...................................................................................... 6
Figure 2-5 Stability frame. ................................................................................. 7
Figure 2-6 Wind frame....................................................................................... 8
Figure 2-7 Airfoil shape. .................................................................................... 9
Figure 2-8 Wind triangle. ................................................................................. 12
Figure 2-9 UltraStic25-e. ................................................................................. 17
Figure 2-10 Flight scenarios ............................................................................ 19
Figure 3-1 Linear velocity linear response validation. .................................... 23
Figure 3-2 Angular velocity linear response validation. .................................. 24
Figure 3-3 Longitudinal (α, q) doublet response. ............................................ 24
Figure 3-4 Lateral dynamics (β, p, r)response of linear and nonlinear model. 25
Figure 3-5 Open loop system. .......................................................................... 26
Figure 3-6 Successive loops approach. ............................................................ 26
Figure 3-7 Lateral autopilot using successive loops. ....................................... 27
Figure 3-8 Lateral inner loops.......................................................................... 28
Figure 3-9 Roll PD controller. ......................................................................... 29
Figure 3-10 Kiφ using root locus. .................................................................... 29
Figure 3-11 Roll PID controller. ...................................................................... 30
Figure 3-12 Course angle controller design ..................................................... 31
Figure 3-13 Course hold controller. ................................................................. 31
Figure 3-14 Sideslip hold loop. ........................................................................ 32
Figure 3-15 Lateral PID controller. ................................................................. 33
Figure 3-16 Longitudinal controller flight regimes. ........................................ 34
Figure 3-17 Root locus of Pitch tracker. .......................................................... 35
Figure 3-18 Pitch attitude hold controller. ....................................................... 35
Figure 3-19 Altitude hold controller using commanded pitch. ........................ 36
Figure 3-20 Airspeed hold controller using commanded pitch. ...................... 37
Figure 3-21 Airspeed hold controller using throttle. ....................................... 38
X