Research On Fault Diganosis And Fault-Tolerant Control Approaches For Time-Delay Systems Based On Observers

In the face of the usual time-delay systems and a class of usual actuator and/or sensor faults, this dissertation researches the problems on fault diagnosis and fault-tolerant control for systems with different time-delays. Firstly, the history of the development on the fault diagnosis and fault-tolerant control is reviewed. The latest research tendency and the main methods are summarized in the fault diagnosis and fault-tolerant control domain, and the fault diagnosis approaches are introduced for time-delay systems. Then, by using optimal control theory, duality principle, linear matrix inequation, and state observer and so on technology, fault diagnosis and fault-tolerant approaches are proposed for systems with different time-delays. The major results of this dissertation are summarized as follows.1. A class of faults is summered and abstracted which often occurs in the actual systems, and the model is established with the concept of"exosystem"and the state space expression for this class of faults with known dynamic characteristics and unknown initial time and initial state. So we can research this class of faults on purpose.2. For the discussed faults and the used observer-based fault diagnosis approach, this dissertation proves the conditions of fault diagnosability when faults are described in two different forms. And the diagnosability criterions are given according to the different conditions of enginvalues of systems and faults, which is the base of the posterior research.3. Beginning from linear systems, this dissertation proposes a new approach for constructing a reduced-order observer according to meeting the observability of error equation and applies it to the fault diagnosis, such that a new fault diagnoser is proposed based on the reduced-order observers which can directly diagnose faults. Utilizing the feedforward -feedback idea and the results of fault diagnosis, a dynamic self-restore fault-tolerant control law and a measured output compensation law are designed.4. In face of the difficulty of fault diagnosis and fault-tolerant control in systems with delayed measurements, a delay-free transformation approach is presented for delayed measurements to transform time-delay systems into delay-free ones in form, which solves the fault diagnosis problem for systems with delayed measurements. By using duality principle, the fault diagnosis problem is transformed into the state feedback problem to research, so that an optimal fault diagnoser is proposed which can not only diagnose faults of systems but also meet the quadratic performance index. A dynamic fault-tolerant switch control law and a dynamic switch measured output compensation law are designed which can switch according to the occurrence conditions of the different faults.5. In face of the difficulty of fault diagnosis and fault-tolerant control in systems with both delayed control and delayed measurements, a diagnoser is designed by introducing and extending the delay-free transformation of control and measurement delays, respectively. An optimal fault-tolerant control is proposed which meets the quadratic performance index, and the physically unrealizable problem of the optimal fault-tolerant control is solved.6. Fault diagnosis and fault-tolerant control approaches are researched for networked control systems which stand for discrete systems with both delayed controls and delayed measurements. A delay-free transformation method of the delayed measurements is presented for discrete systems. A new construction approach of fault diagnoser is presented for discrete systems by introducing the delay-free transformation of control delays, so that a fault diagnosis approach is proposed which can directly diagnose faults for discrete systems. A dynamic self-restore fault-tolerant switch control law and a dynamic switch measured output compensation law are designed for networked control systems.7. For systems with state delays, the asymptotical stability conditions and the guaranteed cost conditions of the fault diagnoser are researched by using duality principle and integrating Lyapunov functional and LMI and so on technology.8. The conclusions are made. And the direction for the future study is indicated.