Fault-Tolerant Control For Two Classes Of T-S Fuzzy Systems With Actuator Faults

The study of the fault-tolerant control (FTC) system, which can guarantee the satisfactory performance when all the components in the system are not only operational but also faulty, has received considerable attention in control theory and practical engineering applications. Since actuators fail most frequently in a real control system, the FTC problem attracts more and more interests. On the other hand, many plants in industry have nonlinear characteristics. T-S fuzzy model is a universal approximator of any smoothly non-linear system on a compact set. Hence, the fault-tolerant control for nonlinear systems based on T-S fuzzy models is an important research issue which is with obvious theoretical significance and engineering value.The main results in the dissertation are as follows:In chapter1, the basic concept of FTC and the detailed summary of the development process of FTC are introduced, respectively. Moreover, the significance of this thesis is presented not only in theory but also in applications. And the corresponding development at both abroad and home is recalled briefly.In chapter2, the problem of FTC for T-S fuzzy systems with actuator faults is investigated. A switched system model is formulated by using the fault partition approach. Then a sufficient condition, which guarantees that the faulty system is exponentially stable, is obtained by combining Lyapunov stability theory, the average dwell time approach and the convex combination technique. The fault tolerant controller is designed in terms of linear matrix inequalities. A numerical example is provided to illustrate the effectiveness of the proposed method.In chapter3, we are concerned with the design problem of FTC for T-S fuzzy systems with time delay and actuator faults. Suppose the transition of fault levels cannot be detected instantaneously, an asynchronous switching fuzzy controller depending on fault levels is put forward. Then a fault-partition-dependent stability criterion is derived by combining Lyapunov stability theory and the free-weighting technique. The fault tolerant controller is designed in terms of linear matrix inequalities, which guarantees the faulty system is exponentially stable. Finally, a numerical example is given to demonstrate the effectiveness of proposed method.In chapter4, the main results of the thesis are concluded, and some research issues in future are proposed.