Study On Fault Detection For Switched Systems

As an important class of hybrid systems, switched systems are of great significance both in theory development and engineering applications. Study on fault detection for switched systems is still in the early stage of development. A few results have been reported in literatures. However, the results often ignore the requirements for the fault detection performance caused by the switching features. Thus, many analysis and design problems deserve further investigation.The fault detection for switched systems is studied in this thesis. Based on the aver-age dwell-time method, this thesis presents some new fault detection methods. Firstly, the weighted l2performance and H_performance for switched systems with mode-dependent average dwell-time are guaranteed, and fault detection filters are designed. For switched linear parameter-varying systems, the design of fault detection filters is translated into the the design of robust filters, and the filter gains are obtained. In virtue of the asynchronous case, the design of asynchronous fault detection filter is considered. Subsequently, simul-taneous fault detection and control for switched systems under asynchronous switching are presented. Finally, the result of simultaneous fault detection and control is expanded further on the reliable control. All the main results are verified by simulation and part of the developed theories is applied to the simulation studies of aircraft model.Chapters1-2summarize and analyze the background and the development of fault detection and switched systems. Preliminaries about the considered problems are also given.Chapter3is concerned with the problem of the fault detection filter design for discrete-time switched linear systems with mode-dependent average dwell-time. Under this switching law, a weighted l2performance and an H_performance are guaranteed for the disturbances attenuation performance and for the fault sensitiveness performance. The fault detection filters are designed to guarantee a weighted l2performance and an H_performance.In Chapter4, the fault detection problem for switched linear parameter-varying sys-tems is considered. The bound of the rate of the parameter is introduced, and the design of the fault detection filter is translated into robust filter design, the filter gains are obtained through satisfying a set of linear matrix inequalities.Chapter5is concerned with the problem of the fault detection filter design for discrete-time switched linear systems under asynchronous switching. For asynchronous switched systems, improved results on the weighted Z2performance and the H_perfor-mance are first given. By the aid of average dwell-time method, the fault detection filters are designed for asynchronous case.The problem of simultaneous fault detection and control for asynchronous switched systems is studied in Chapter6. The fault detectors and controllers are designed as a single unit, and generates two signals:a detection signal and a control signal, which are used to detect faults and guarantee control indices, respectively. A two-step procedure is adopted to obtain the solutions through satisfying a set of linear matrix inequalities.In Chapter7, the fault detection and control problem for switched systems with actuator faults is considered. The actuator faults, especially ’destabilizing failure’, are included. The detector/controller is designed simultaneously such that the closed-loop system switches under average dwell time, meanwhile, the alarm is generated when the fault is detected, then the controller is switched to allow the norms of the states of the subsystem to increase within the acceptable limits. Thus, a switching strategy which combines average dwell time switching with event-driven switching is proposed. Subse-quently, since the actuator fault can be detected after a time period when the fault occurs, the asynchronous case is considered in this two-stage switching strategy. Thus, Chapter7investigates the simultaneous fault detection and control problem for switched systems under a two-stage switching and asynchronous case, and guarantees fault detection objec-tive and control objective. Finally, a numerical example illustrates the effectiveness of the proposed method in this chapter.Finally, the results of the dissertation are summarized and further research topics are pointed out.