Fault Tolerant Control Of Switched System With Application To Flight Control System

System faults such as actuator failures,structural damage may cause system performance deterioration and even lead to catastrophic accidents.To enhance the reliability and safety of system,fault tolerant control has become an important direction of systems and control research,with applications in broad and emerging areas of science and technology.As a kind of hybrid systems,switched systems have used in more and more industries,and fault tolerant control of switched systems attracted great attention in the past decade.In this paper,firstly a generalized separation principle of switched linear systems have been proposed,then the acceptable performance degradation analysis of switched systems have been investigated,and at last the model reduction of switched linear systems have been investigated.Firstly,the research background and significance of fault tolerant control,generalized separation principle,performance degradation and model reduction are introduced.An overview of the current state of study and research about fault tolerant control of switched systems is presented.We study the generalized separation principle of switched systems,performance degradation analysis of switched systems and model reduction of switched linear systems,and have obtained systematic results.The key contributions are summarized as follows:(1)Generalized separation principle of switched systems.For switched linear systems,after fault occurs,a generalized separation principle of switched systems is proposed,and the individual fault diagnosis and fault tolerant control scheme are proposed.The theoretical results are further applied to Hi MAT vehicle to illustrate its effciency and applicability.(2)Performance degradation analysis of switched systems.Once a fault occurs,system performance may not be as good as that of the original system due to some physical limitations.A new concept of accepting performance degradation,which evaluated by converging rate and stability,is proposed for switched systems.The relation between the converging rate of the whole switched system and the eigenvalues of each subsystem is established,based on which the accepting performance degradation is evaluated quantitatively in the presence of process and actuator faults.The derived results are further verified by the simulation of an application to the highly manoeuvrable technology vehicle model.(3)Model reduction of switched linear systems.First,the conditions,which guarantee the stability of fault tolerant linear system and the error between the states of linear system and reduced order linear system is in a certain range,are proposed.Then,the conditions are further extended to switched linear systems.It shows that fault tolerant switched system can be reduced by the same truncated of original switched system without faults if fault matrices satisfy some conditions.At last,simulation results show the effectiveness of the proposed approach.