Fault Detection Methods Analysis For Switched Systems With All Modes Unstable

In recent years,switched system has been a very hot topic,because the switched system can be widely used in aerospace,power electronics,biological medicine and other aspects.Its application scope is an important factor to maintain its research vitality.With the continuous advance of science and technology and the continuous breakthrough of various top technologies,our production and life have been promoted to a great level,and many systems will face more and more demanding operation environment and higher and higher standard operation effect.These increasing requirements have brought great challenges to our design work,including taking into account the operating environment and effects of the system,as well as paying attention to unexpected situations that may occur at any time.Subsystems of switched systems are generally stable,but some unexpected disturbance or failure may cause them to mutate.Therefore,it is of great significance to study the stability of switched systems with unstable subsystems.In addition,we found that there are not enough studies on fault detection in existing literature for switched systems with all unstable subsystems,so the main contents of this paper can be summarized as follows:The first is the robust fault detection filter design for switched systems with unstable subsystems.By selecting the proper filter form and introducing the weighted fault matrix,the sufficient conditions that the augmented system can be stable and robust are obtained by using the linear matrix inequality method.Finally,the simulation results verify the effectiveness of the proposed filter.Considering the performance of the system in a limited time interval and the characteristics of the singular system,the second is the robust fault detection filter for switched singular system with unstable subsystem.Firstly,the conditions to ensure the singular system is regular and impulse free are given.Secondly,sufficient conditions are given for its finite time-bounded and finite time-stable.Then,a solvable condition ensuring finite time L2-gain is given by linear matrix inequalities.Finally,the simulation results verify the effectiveness of the proposed filter.The third is the design of fault detection observer for switched systems with unstable subsystems.The error system is obtained by using Luenberger type observer.The state matrix and the output matrix of the system are considered as the cause of the instability of the error system.The stability and robustness of the error system are analyzed,and the discretized Lyapunov function method is used to obtain the solvable conditions for stability and H?performance.Finally,the simulation results verify the effectiveness of the proposed observer.The fourth is the H?/H_observer study of switched systems with unstable subsystems.The fault and disturbance of the system are considered separately,and their influence on the error signal is studied respectively.An error system with disturbance and fault is obtained by using the observer form similar to the third one.Using the method of discretized Lyapunov function,the average dwell time is obtained to ensure the stability.Under the condition of ensuring stability,the sufficient conditions and solvable conditions for ensuring the performance of H? and H_are proposed respectively.Finally,the simulation results verify the effectiveness of the proposed observer.Fifthly,the concept of interval observer is introduced for the inaccuracy of traditional observer in fault detection.The error system is obtained by setting the upper and lower interval observer of the system.Taking the unobservable condition of the original system as the cause of the instability of the error system,the sufficient conditions to ensure the stability are obtained by means of the discretized Lyapunov function and the average dwell time method.Then,the influence of system disturbance and fault signal is studied respectively,and sufficient conditions and solvable conditions are obtained for the error system to have H? performance and H_performance.Finally,the simulation results verify the effectiveness of the proposed observer.