Research On H_-/H_? Fault Detection Approaches In Finite Frequency Domain

With an increasing demand for higher safety and more reliable standards,the problem of fault detection(FD)becomes a hotspot in the control field gradually.FD technology is an important approach to improve safety and reliability for dynamic systems.Due to an importance and development of robust control theory,the robust FD approaches have attracted lots of attention.Among them,the finite frequency H_-/H_? FD method can sufficiently consider the frequency effects of the faults and disturbances.In addition,the method is not only robust to the external noise or disturbances and model uncertainties but also sufficiently sensitive to the fault signals.Although the experts and scholars at home and abroad have achieved many excellent results in this field,there are still some problems in the existing results to be further investigated.For example,the existing H_-/H_? FD method cannot be directly applied to deal with the nonlinear singular time-delay systems;the FD problem of networked control systems with random time delays and data missing simultaneously are not full investigated in the existing results;the known schemes cannot detect the small low-frequency faults.Corresponding to the aforementioned problems,this thesis,based on previous works of others,presents some new FD methods.The main contributions of this thesis are summarized as follows:(1)For T-S fuzzy singular systems with multiple time delays,a new finite frequency H_-/H_? FD method is developed.In the time domain,a fuzzy singular type of Lyapunov-Krasovaskii function is constructed.It is proved that the function can include the existing ones as a special case.Therefore,it is less conservative.In the frequency domain,the frequencies of fault signals and disturbance signals are considered to be finite.Based on finite frequency fault sensitivity and disturbance attenuate performance indexes,generalized KYP lemma is extended to T-S fuzzy singular systems by combing Parseval theorem and S-procedure.Compared with the existing results,the proposed scheme can detect a smaller fault signal.(2)For the networked control systems(NCS)with random time delays and data missing simultaneously,this thesis discusses the problem of finite-frequency FD.A new multi-parameters-varying Markov jumping system(MPVMJS)model is established to describe the considered NCSs.Compared to the existing NCS model,the controller-actuator(C-A)delay along with C-A data dropout and the sensor-controller(S-C)delay along with S-C data drop-out are considered in NCSs,which have great potential in practical applications.Combing Parseval theorem and S-procedure,an H_-/H_? FD filter is designed and its convex design conditions are derived in terms of solving a set of linear matrix inequalities(LMIs).Finally,the results of the dissertation are summarized and further research topics are pointed out.