Title Page
Contents
Abbreviations 11
Abstract 16
CHAPTER 1. INTRODUCTION 17
1.1. Overview 17
1.2. Research objectives 20
1.3. Limitation of the dissertation 21
1.4. Dissertation outline 21
CHAPTER 2. OVERVIEW ON FAULT DIAGNOSIS AND FAUTL-TOLERANT CONTROL 22
2.1. Introduction 22
2.2. Basic concepts 22
2.2.1. Basic definition 22
2.2.2. Fault classification 23
2.3. Fault diagnosis method 24
2.4. Fault tolerant control 25
CHAPTER 3. MODELLING AND PROBLEM STATEMENTS OF THE EHA SYSTEM 26
3.1. Introduction 26
3.2. Nonlinear EHA model with fault and problem formulation 26
3.3. Matched, mismatched disturbance, and system faults 28
3.3.1. Matched and mismatched disturbance 28
3.3.2. System faults 29
3.4. Experiment apparatus 31
CHAPTER 4. INTERNAL LEAKAGE FAULT-TOLERANT TRACKING CONTROL 34
4.1. Introduction 34
4.2. Problem formulation 35
4.3. Proposed control design for EHA 36
4.3.1. Coordinate transformation and system model transformation 37
4.3.2. Fault detection and identification using time delay estimation 39
4.3.3. Control law design 40
4.4. Simulation results 44
4.4.1. Simulation setup 44
4.4.2. Simulation result 45
4.5. Experimental verification 48
1) Scenario 1 48
2) Scenario 2 50
4.6. Chapter summary 52
CHAPTER 5. ACTUATOR FAULT-TOLERANR TRACKING CONTROL WITH BIAS AND LOSS OF EFFECTIVENESS FAULT 53
5.1. Introduction 53
5.2. Problem description 54
5.3. FTC design and stability analysis 56
5.3.1. Nominal control design 57
5.3.2. Reconfigurable control design 59
5.4. Numerical simulation 63
5.4.1. Simulation setup 63
5.4.2. Simulation result 65
5.5. Comparative experimental results 67
5.5.1. Experiment setup 67
5.5.2. Experiment results 67
5.6. Chapter summary 70
CHAPTER 6. ROBUST SENSOR FAULT-TOLERANT TRACKING CONTROL 72
6.1. Introduction 72
6.2. Problem statement 73
6.3. NUIO-based fault identification for EHA 75
6.4. Observer-based fault-tolerant tracking control 78
6.4.1. ESO design 78
6.4.2. FTC design with ESOs and NUIO 80
6.5. Simulation results 84
6.5.1. Simulation setup 84
6.5.2. Simulation result 86
6.6. Chapter summary 93
CHAPTER 7. CONCLUSION AND FUTURE WORKS 95
7.1. Conclusion 95
7.2. Future works 96
PUBLICATIONS 98
REFERENCES 100
Table 3.1. Setting parameters of the real EHA system 32
Table 3.2. Electro-hydraulic system parameters 33
Table 4.1. Performance indices of three controllers in simulation. 47
Table 4.2. Performance indices of three controllers in experiment. 52
Table 6.1. Summary of performance indices 90
Figure 1.1. Various applications of EHA 17
Figure 2.1. Fault classification with respect to location 23
Figure 2.2. The block diagram of FTC system 25
Figure 3.1. Schematic model of a double-rod EHA 26
Figure 3.2. Possible faults of a double-rod EHA system 29
Figure 3.3. The experimental equipment of the EHA system. 32
Figure 4.1. The schematic model of the EHA under ILF 35
Figure 4.2. Structure of the proposed control scheme 36
Figure 4.3. Lumped disturbance estimation in simulation: a) without fault, b) Abrupt fault 45
Figure 4.4. Performances of three controllers in simulation, scenario 1 46
Figure 4.5. Performances of three controllers in simulation, scenario 2 47
Figure 4.6. Lumped disturbance estimation in experiment: a) without fault, b) Abrupt fault. 48
Figure 4.7. Performances of three controllers in experiment, scenario 1 49
Figure 4.8. Estimated velocity and acceleration of SEOD in experiment. 50
Figure 4.9. Performances of three controllers in experiment, scenario 2 51
Figure 4.10. Adaptive gain in experiment 51
Figure 5.1. Schematic of the electro-hydraulic actuator with actuator faults 54
Figure 5.2. Sketch of the proposed control approach 56
Figure 5.3. Lumped disturbance and LOE fault estimation in the simulation. 65
Figure 5.4. Performances of the proposed controller in the simulation. 66
Figure 5.5. The overall tracking error of different control methods 66
Figure 5.6. Result of performance indexes in the simulation 67
Figure 5.7. Mismatched, matched disturbance and LOE fault estimation of the proposed method in the experiment. 68
Figure 5.8. Performances of three control methods in experiment 1 69
Figure 5.9. Result of performance indexes in the experiment. 69
Figure 5.10. Performances of three control methods in experiment 2 70
Figure 6.1. Schematic of the electro-hydraulic actuator with sensor faults 73
Figure 6.2. Schematic view of the proposed control scheme 75
Figure 6.3. FDEI of NUIOs in case of only fault in position sensor. 86
Figure 6.4. FDEI of NUIOs in case of only fault in velocity sensor. 87
Figure 6.5. FDEI of NUIOs in case of only fault in pressure sensor. 87
Figure 6.6. FDEI of NUIOs in case of simultaneous fault. 88
Figure 6.7. Performances of comparative controllers in case 1 89
Figure 6.8. Lumped disturbance estimation of ESOs in case 1 90
Figure 6.9. Tracking performance of different control methods in case 2 91
Figure 6.10. Lumped disturbance estimation of ESOs in case 2 92
Figure 6.11. Lumped disturbance estimation of ESOs in case 3 93
Figure 6.12. Tracking errors of two control methods in case 3 93