Research On Robust Fault Estimation And Fault-Tolerant Control For Nonlinear Time-Delay Systems Based On T-S Fuzzy Model

Fault diagnosis and fault-tolerant control technology have been paid attention to and studied by many scholars as an important method to maintain system stability and safety.Therefore,many control theory methods have been proposed and verified.However,with the rapid development of automation,the actual control system is subject to more and more uncontrollable factors,such as nonlinearity,time delay,outer interference,etc.,which requires us to seek new development and breakthrough based on classical control theory.For complex nonlinear systems,it is difficult to model them,but fuzzy control techniques can effectively control systems with nonlinear and time-varying properties.In particular,the T-S fuzzy model has its own advantages in the process of dealing with nonlinear systems.It can connect a series of linear models through fuzzy membership functions,which can ensure that this nonlinear system is approximated with arbitrary accuracy.Therefore,many linear system control theory results can be applied to nonlinear systems described based on T-S fuzzy models.First,the research object of this paper is a nonlinear time-delay system with external disturbances,actuator and sensor fault described based on the T-S fuzzy model.The constructed proportional-integral observer realizes the simultaneous estimation of the state,actuator and sensor faults in the system.Then,the Lyapunov function is constructed to analyze the stability of the system,and a delay-dependent conclusion described by a linear matrix inequality is obtained.Finally,the effectiveness of the proposed method is verified by a simulation example.The designed observer can simultaneously estimate the actuator and sensor faults and meet the system’s given H∞ performance index.Then,the time-varying delays of the previous study are extended to the case of interval-time-varying delays,which are closer to the practical system.Although the design idea of the proportional-integral observer is the same as before,in the process of constructing the Lyapunov function,we used the upper and lower bound information of the interval time-varying delay.Compared with the time-varying delay,the conclusion obtained by the interval-varying delay are less conservative.Finally,the effectiveness of the proposed method is verified by a simulation example.The designed observer can simultaneously estimate the actuator and sensor faults and meet the system’s given H∞ performance indexFinally,based on the fault estimation information obtained in the previous two chapters,this paper designs the output fault-tolerant controller for the above two systems.The controller uses the output of the original system as the input of the fault-tolerant controller to compensate for the fault in the system.And for most systems,the output of the system is easy to get.Therefore,the application range of the fault-tolerant controller based on the principle of output feedback is wider.Finally,simulation examples verify that the controller can compensate for faults in the system and keep the system stable.