Study On Actuator Saturation And Fault Detection For Switched Linear Systems

As a special class of dynamic systems,a switched system is a kind of important and multi-model hybrid systems.Due to its important theoretical significance and wide prac-tical application background,the researchers pay more and more attention to the study of such systems.On the other hand,most of the practical systems are inherent actuator saturation.If we ignore actuator saturation in the controller design,it may lead perfor-mance degradation or even cause the instability of the system.Since the switched system contains both continuous and discrete dynamics,this makes the study of switched system with actuator saturation is more difficult to deal with.Therefore,the research results of this kind of system is also very limited.With the rapid development of industrial technology,the actual engineering reliabil-ity and security of the system is also put forward to higher requirements.Therefore,fault detection has become a hot issue in the field of control.Based on the actual background of the switching system,the study for the fault detection problem of the switched sys-tem also has a great value.Because the switching can impact on the performance of the system itself,in this case,the sensitivity to the fault also becomes more complicated to guarantee.So far,the research of this kind of problem is still in its infancy.The dissertation investigates the L₂?l₂?-again and output feedback passification of switched systems with saturation control,and the fault detection of the switched linear system.The main conclusions are presented as follows.?1?For the continuous-time switched system with actuator saturation,the problem of L₂-gain has been studied.Based on the approach of average dwell-time,when the state information can not be completely obtained,a quasi-LPV output feedback controller is designed to guarantee the overall system is with disturbance tolerance capacity and L₂ performance.By introducing the slack matrices,our results has less conservative.?2?The l₂-gain analysis for the switched delay systems which have actuator satura-tion is investigated.The proposed mode-dependent average dwell time not only allows each subsystem can have their average dwell time but also depends on the state delay.Un-der this switching law,the output feedback controllers with saturation are designed,which make the systems meet the l₂-gain.?3?The output feedback passification for switched linear systems with saturating ac-tuators is studied.When the system state is not available from measurements,the switch-ing law and dynamic output feedback controllers which only use the measurable output are designed to guarantee the closed-loop switched system is passive,even each subsys-tems is not feedback passive.?4?Based on the previous results,the problem of output feedback passification for switched systems is further studied.By designing the output feedback controllers and the appropriate switching law simultaneously,the sufficient conditions for passivity and the disturbance tolerance capacity of the switched system can be obtained.More importantly,under this switching law,during the dwell time,we allow the storage functions to increase,which release the requirement of the existing results.At the same time,the switching law we proposed has the advantage of both the state-dependent and time-dependent switching.?5?The issue of asynchronous fault detection for continuous-time switched systems with time delays is studied.The delays appear in the state and the switching signal.A novel switching strategy is constructed,which depends on both the state delay and the switching delay.Under the delay dependent switching strategy,fault detection filters are designed to guarantee the switched systems meet the disturbance attenuation and fault sensitivity conditions.These realize the fault detection objectives.?6?The fault detection and robust control for the switched systems with dwell time are investigated where the dwell time is unknown.During the dwell time,the Lyapunov function is allowed to be increasing and every subsystem has its own maximal dwell time.For the problem of robust control,the result can include the existing ones.According to upper bound of the mode-dependent dwell time,a novel switching strategy is constructed to guarantee the closed-loop switched systems have H_index and L₂ gain.Thus,if the Lyapunov function is finite growth,the faults can also be detected.At last,the suffi-cient conditions for the existence of the feedback controllers,residual generators,and the switching law can be converted to a convex optimization problem,which realize the fault detection objectives.At the end,the conclusions together with the perspectives are presented.