Title Page
Contents
Abbreviations 13
ABSTRACT 14
Chapter 1. INTRODUCTION 15
1.1. Overview 15
1.2. Research objectives 16
1.3. Limitations 17
1.4. Thesis outline 18
Chapter 2. OBSERVER DESIGN TECHNIQUES FOR ROBOT MANIPULATORS 19
2.1. Introduction 19
2.2. Robot manipulator dynamics 19
2.3. Extended state observer 19
2.4. Extended sliding mode observer 21
2.5. Sliding mode observer 23
2.6. Discussion 24
Chapter 3. APPLICATION TO FAULT-TOLERANT CONTROL PROBLEM OF HYDRAULIC MANIPULATORS 25
3.1. Introduction 25
3.2. System dynamics 28
3.2.1.Mechanical system 28
3.2.2. Hydraulic system 29
3.2.3. Total system dynamics 30
3.3. Proposed observer-based control algorithm 31
3.3.1. Disturbance observer design 32
3.3.2. Online-fault identification 33
3.3.3. Control design 35
3.4. Stability analysis 37
3.5. Numerical simulation 38
3.5.1. Simulation setup 39
3.5.2. Controllers for comparison 41
3.5.3. Simulation results 42
3.6. Discussion 47
Chapter 4. APPLICATION TO ADMITTANCE CONTROL PROBLEM OF HYDRAULIC MANIPULATORS 49
4.1. Introduction 49
4.2. System dynamics 51
4.2.1.Mechanical system modeling 51
4.2.2. Hydraulic system modeling 52
4.3. Proposed observer-based control algorithm 53
4.3.1. Extended sliding mode observer design 53
4.3.2. Matched disturbance observer design 54
4.3.3. Admittance control design 55
4.4. Numerical simulation 57
4.4.1. Simulation setup 57
4.4.2. Controllers for comparison 58
4.4.3. Simulation results 59
4.5. Discussion 62
Chapter 5. APPLICATION TO CONTOURING CONTROL PROBLEM OF ROBOTIC EXCAVATORS 63
5.1. Introduction 63
5.2. System dynamics 65
5.2.1. Kinematics analysis 65
5.2.2. Dynamics analysis 66
5.3. Extended state observer 67
5.4. Proposed observer-based control algorithm 68
5.4.1. Normal tracking control 70
5.4.2. Tangential and angular tracking control 72
5.4.3. Trajectory generation 72
5.5. Numerical simulation 73
5.5.1. Simulation setup 73
5.5.2. Controllers for Comparison 75
5.5.3. Simulation results 76
5.6. Conclusion 83
Chapter 6. CONCLUSION AND FUTURE WORKS 84
6.1. Conclusions 84
6.2. Future works 84
Published papers and patents 86
References 87
Table 3-1. Mechanical parameters 39
Table 3-2. Hydraulic parameters 40
Table 3-3. Maximum of the tracking errors 43
Table 3-4. Average of the tracking erros 43
Table 3-5. Standard deviation of the tracking errors 44
Table 3-6. RMSE of the tracking errors 44
Table 4-1. Mechanical parameters 56
Table 4-2. Hydraulic parameters 57
Table 4-3. Performance indices in case 1 60
Table 4-4. Performance indices in case 2 62
Table 5-1. Model parameters 73
Table 5-2. Geometric dimensions 74
Table 5-3. Control parameters 75
Fig. 3-1. Schematic diagram of an n-DOF manipulator 27
Fig. 3-2. A typical electrohydraulic actuation system 29
Fig. 3-3. Proposed active FTC scheme 32
Fig. 3-4. Diagram of the reduced HyQ leg prototype. 39
Fig. 3-5. Structure of the simulation in MATLAB Simulink. 41
Fig. 3-6. Position tracking performances of comparative controllers 43
Fig. 3-7. Position tracking errors of comparative controllers 43
Fig. 3-8. Fault detection performance 44
Fig. 3-9. Internal leakage fault identification performance 45
Fig. 3-10. Mismatched lumped disturbance/uncertainty estimation performance 45
Fig. 3-11. Matched lumped disturbance/uncertainty estimation performance 46
Fig. 3-12. Pressures of both chambers in cylinder 1 46
Fig. 3-13. Pressure of both chambers in cylinder 2 47
Fig. 3-14. Control signals of comparative controllers 47
Fig. 4-1. Proposed admittance control scheme for hydraulic robots 53
Fig. 4-2. Reduced HyQ leg prototype. 56
Fig. 4-3. Contact force estimation performance 59
Fig. 4-4. Position of the end-effector 59
Fig. 4-5. Control signal for servo valves 60
Fig. 4-6. Reference trajectory and environment position. 61
Fig. 4-7. Contact force estimation performance and contact force estimation error in the y-axis 61
Fig. 4-8. Admittance tracking performance and the error between the actual position and the desired position in the y-axis. 61
Fig. 5-1. Schematic diagram of the investigated excavator. 66
Fig. 5-2. Tracking error decomposition schematics. 68
Fig. 5-3. Diagram of the proposed control. 69
Fig. 5-4. Mini-excavator model 73
Fig. 5-5. Simulink block diagram 76
Fig. 5-6. Excavator reference motion in case 1 76
Fig. 5-7. Arm speed reference signal 77
Fig. 5-8. Performance of excavator with respect to a) Contouring accuracy, b) Tangential accuracy, c) Orientation accuracy, and d) Contour shape. 78
Fig. 5-9. Estimation performance in terms of a) position, b) velocity, and c) lumped disturbances/uncertainties. 78
Fig. 5-10. Force control signal of a) boom cylinder, b) arm cylinder, and c) bucket cylinder. 79
Fig. 5-11. Excavator reference motion in case 2 80
Fig. 5-12. Performance of excavator with respect to a) Contouring accuracy, b) Tangential accuracy, c) Orientation accuracy, and d) Contour shape. 81
Fig. 5-13. Estimation performance in terms of a) position, b) velocity, and c) lumped disturbances/uncertainties. 82
Fig. 5-14. Force control signal of a) boom cylinder, b) arm cylinder, and c) bucket cylinder. 82