Depth, Linear Speed and Attitude Control Using Gyro and Thrust Propeller of an Underwater Robot
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Depth, Linear Speed and Attitude Control Using Gyro and Thrust Propeller of an Underwater Robot by Akhila Madhushan Jayasekara A thesis submitted in partial fulfillment of the requirement for the degree of Master of Engineering in Mechatronics Examination Committee: Prof. Manukid Parnichkun (Chairperson) Dr. A. M. Harsha S. Abeykoon Dr. Mongkol Ekpanyapong Nationality: Sri Lankan Previous Degree: Bachelor of Science in Engineering in Mechatronics Asian Institute of Technology Thailand Scholarship Donor: AIT Fellowship Asian Institute of Technology School of Engineering and Technology Thailand December 2017 i ACKNOWLEDGMENTS This research study would have been impossible without the guidance of everyone around me. Special thanks goes to Prof. Manukid Parnichkun, Dr. A. M. Harsha S. Abeykoon, and for Dr. Mongkol Ekpanyapong advising for my research. I also be thankful to all the lectures and staff from ISE department who taught me very inestimable lessons and for their commitments that made me insightful in this field. My parents, Dr. Dayananda Jayasekara and Seetha Ranasinghe, always have been my pillar of strength and guidance for my studies, I am truly grateful for their support. I am thankful for my colleagues for the help and for all the moral support I received throughout the two years of masters. There were many who help me in Sri Lanka and Thailand to finish this research, I am truly grateful for all your support and guidance. ii ABSTRACT A number of researches have been conducted to date on various methods and techniques to make underwater vehicles better and risk free. The ocean is a vast 3-D environment and it follows that an ocean research tool, such as the underwater vehicle, should ideally be able to move freely in any direction within its surroundings. Most underwater robots uses rudders, propellers and many numbers of water pumps to create its motion, changes its altitude and keep its stability. Actuators that deflect fluid momentum, such as fins and rudders, lose control authority at low velocities. Although actuators that generate fluid momentum, such as thrusters, can provide low-velocity control, the use of multiple thrusters increases drag, reducing efficiency particularly when travelling at high speeds. The ability to adopt and maintain any attitude on the surface of a sphere with a zero radius turning circle would allow an underwater robot to approach its missions in a fully 3-D manner, optimizing the use of its thrusters, sensors, and power supply in a way that has not been possible previously. Purpose of this thesis is to approach the subject in a different direction and make advancements, the zero-G concept. This method is mainly uses in satellites to control its motions. Keywords: Underwater Remotely Operated Vehicle (ROV), Autonomous Underwater Vehicle (AUV), Control Momentum Gyro (CMG) Proportional-Integral-Derivative controller (PID), Linear-Quadratic Regulator (LQR), Center of Mass (CM) iii TABLE OF CONTENTS (Cont’d) CHAPTER TITLE PAGE TITLE PAGE i ACKNOWLEDGEMENTS ii ABSTRACT iii TABLE OF CONTENTS iv LIST OF FIGURES vi LIST OF TABLES viii 1 INTRODUCTION 1 1.1 Introduction 1 1.2 Problem Statement 2 1.3 Objective 2 1.4 Limitations and Scope 2 2 LITERATURE REVIEW 3 2.1 Introduction 3 2.2 Systems with Reaction Wheels 3 2.3 Balance Control of Bicycle Robot 4 2.4 Underwater Robots 7 3 METHODOLOGY 11 3.1 Mathematical modelling of the system 11 3.2 System overview 13 3.3 Hardware model 15 4 SIMULATION AND RESULTS 23 4.1 PID simulations 23 4.2 State space and LQR calculations 33 5 CONCLUSION AND RECOMMENDATION 40 5.1 Conclusion 40 5.2 Recommendation 40 iv REFERENCES 41 v LIST OF FIGURES (Cont’d) FIGURE TITLE PAGE Figure 2.1 A cutaway view of a typical reaction wheel 3 Figure 2.2 Schematic of tumbler-reaction system 4 Figure 2.3 Self-balancing bicycle robot 5 Figure 2.4 The scheme of bicycle robot 5 Figure 2.5 The simulation results of single gyroscopic stabilizer 6 Figure 2.6 The simulation results of double gyroscopic stabilizer 6 Figure 2.7 Single gimbal control momentum gyro 7 Figure 2.8 Pyramid configuration of CMGs 8 Figure 2.9 Control system block diagram 8 Figure 2.10 A photo of the AUV 9 Figure 2.11 Mechanism of actuators 9 Figure 2.12 Mechanism of actuators 10 Figure 3.1 Motor placement of the ROV 11 Figure 3.2 Forces acting on the ROV body 11 Figure 3.3 Translational forces acting on the ROV body 13 Figure 3.4 System overlay 14 Figure 3.5 Solid works design of the ROV 15 Figure 3.6 Actual model of the ROV 15 Figure 3.7 Actual model of the ROV 16 Figure 3.8 Final reaction wheel 16 Figure 3.9 Weight adjusting component 17 Figure 3.10 The broken propeller 17 Figure 3.11 3D printed new propeller 18 Figure 3.12 Electronic components 18 Figure 3.13 Pololu motor 19 Figure 3.14 High current motor driver 19 Figure 3.15 Brushless thrust moto 20 Figure 3.16 High current ESC 20 Figure 3.17 Sensor module 21 Figure 3.18 Barometric pressure sensor 21 Figure 3.19 Surface communication unit 22 Figure 3.20 Surface communication 22 Figure 4.1 Response to impulse disturbance of uncontrolled system in yaw 23 Figure 4.2 Response to impulse disturbance of PID system in yaw 24 Figure 4.3 Yaw disturbance 25 Figure 4.4 Response to impulse disturbance of uncontrolled system in pitch 26 Figure 4.5 Response to impulse disturbance of PID system in pitch 27 Figure 4.6 Experimental response in pitch angle to impulse disturbance 28 Figure 4.7 Experimental response in pitch angle to impulse disturbance 29 Figure 4.8 Response to impulse disturbance of uncontrolled system in roll 30 Figure 4.9 Response to impulse disturbance of PID system in roll 31 Figure 4.10 Experimental response in roll angle to impulse disturbance 32 vi Figure 4.11 Experimental data of depth control by moving forward and changing 33 pitch angle Figure 4.12 Response to impulse disturbance of LQR system for yaw 34 Figure 4.13 Experimental response in yaw angle to impulse disturbance 35 Figure 4.14 Response to impulse disturbance of LQR system for pitch 36 Figure 4.15 Experimental response in pitch angle to impulse disturbance 37 Figure 4.16 Response to impulse disturbance of LQR system for roll 38 Figure 4.17 Experimental response in roll angle to impulse disturbance 39 vii LIST OF TABLES TABLES TITLE PAGE Table 2.1 List of researches on different types underwater vehicles 10 Table 4.1 Values of inertia and coefficient of drag 34 viii CHAPTER 1 INTRODUCTION 1.1 Introduction One of the major portions of mechatronics is control algorithms. With the advancement of mechatronics engineering, immense interest is of mobile robots has been reported in last few decades. Many researchers are developing and using control algorithms due to its potential applications which may include intelligent vehicles, recue robots, underwater robots, flying robots and drones, etc. Although a many great numbers of researches being done on flying robots and land vehicles, researches on underwater robots and vehicles is relatively low. Exploring the deep sea is a high risk task. Even if the vessel is designed to endure very high water pressure in greatest depths, malfunctions and emergencies can happen. Therefore having a human crew in the craft is dangerous. Utilizing advanced control algorithms and robotic technology, unmanned vehicles can be given the task. A number of researches have been conducted to date on various methods and techniques to make underwater vehicles better and risk free. The ocean is a vast 3-D environment and it follows that an ocean research tool, such as the underwater vehicle, should ideally be able to move freely in any direction within its surroundings. Most underwater robots uses rudders, propellers and many numbers of water pumps to create its motion, changes its altitude and keep its stability. Actuators that deflect fluid momentum, such as fins and rudders, lose control authority at low velocities. Although actuators that generate fluid momentum, such as thrusters, can provide low-velocity control, the use of multiple thrusters increases drag, reducing efficiency particularly when travelling at high speeds. The ability to adopt and maintain any attitude on the surface of a sphere with a zero radius turning circle would allow an underwater robot to approach its missions in a fully 3-D manner, optimizing the use of its thrusters, sensors, and power supply in a way that has not been possible previously. Purpose of this thesis is to approach the subject in a different direction and make advancements, the zero-G concept. This method is mainly uses in satellites to control its motions. The system uses gyro-momentum to control the attitude of the vehicle. The gyroscope is an interesting display of motion and dynamics. The movement of a gyroscope’s spin axis causes a torque which results in the precession seen in spinning tops and other gyroscope based applications. With the dynamics of gyroscope motion understood, we can develop such a system. 1 1.2 Problem Statement As mentioned in the introduction actuators that deflect fluid momentum is not very efficient in controlling the attitude of an underwater explore robot. Maneuverability and the stability is very important to such a robot. Therefore the purpose of this project is to develop an efficient system to control the attitude of an underwater robot. 1.3 Objective The main objective of this project is to develop an underwater robot system and design a controller that can control pitch, yaw, roll and the stability of an underwater vehicle without using fluid momentum displacement methods.