Researches On Robust Fault Detection For Discrete Switched Time-Delay Systems

In practical engineering applications,due to the continuous expending scale of control system,increasing complexity and the huge investment,the system reliability and security should be improved urgently.On the other hand,the time-delay and uncertain parameter are prevalent in the control system,the above factors will lead system performance degradation and even cause system instability.However,in the event of faults onactuators,sensors,or other system components,the desired performance of closedloop control system can not be ensured,and even instable.The technology of faultdetectionis an effective method to solve this problem.In order to improve the performance of fault detection filters,in this thesis,by utilizing the Lyapunov-Krasovskii function(LKF)theory and LMI technique,we systematically and further study the problems of robust performance analysis,state-feedback controller and filter synthesis design for switched time-delay systems.The results obtained in this thesis have less conservatism and computational complexity,because the delay decomposition approach,reciprocally input-output method and a two-term approximation approach were applied in the treatment process of the delay.The main research can be briefly described as follows:(1)A fault detection(FD)and control co-design scheme is studied for discrete-time switched systems with timevarying delays under an arbitrary switching signal in a network communication.By the average dwell-time scheme and a Lyapunov-Krasovskii functional(LKF),a novel delay-dependent sufficient condition is developed to ensure the resulting error system to be exponentially stable in the mean-square sense with an optimizeddisturbance attenuation level.At the same time,the solution of the parameters for the fault detection filter and controller co-design is characterized in terms of the feasibility of a convex optimization problem.Finally,A numerical example is given to illustrate the effectiveness of the obtained results.(2)On the basis of(1),a fault detection(FD)and control co-design scheme is considered for discrete-time switched systems with model uncertainties.In order to improve the performance of the system and make the system more easily detectable,Different from the method of previous chapter,this chapter introduces the fault weighting matrix(),which limits the weighted frequency in the spectral range for the fault signal.The discrete-time switched networked system is first transformed into the form of interconnection of two subsystems by applying an input-output method and a two-term approximation approach,which is employed to approximate the time-varying delay.Our attention is focused on the design of FDF such that,for all data missing conditions,the overall fault detection dynamics are input-output stable in mean square and a guaranteed performance is ensured.Sufficient conditions are first established via performance analysis for the existence of the desired FDF,meanwhile,the corresponding solvability conditions for the desired FDF gains are characterized in terms of the feasibility of a convex optimization problem.Finally,concluding remarks are given.Some unsolved problems and development direction for the robust fault detection of switched time-delay systems are proposed.Furthermore,the prospects of the further study are given.