Research For Adaptive Fault-Tolerant Control Of Uncertain Dynamic System Based On Event-Triggered Strategies

With the development of modern industry,the internal performance requirements of nonlinear control systems have been improved.Actuator failures often occur in the operation of the systems,which will cause serious accidents and even endanger lives when applied in practice.The occurrence of adaptive fault-tolerant control can ensure that the systems with actuator faults can keep stable and have better performance.In addition,signal blocking and waste of resources may occur during the transmission of control signals,while event-triggered control is an effective means to improve resource utilization.In this dissertation,based on event-triggered strategy,combined with adaptive control,backstepping technique and FLSs,the fault-tolerant control problems of nonlinear systems are discussed.The main contents include:In Chapter 2,the adaptive asymptotic tracking fault-tolerant control for the nonlinear system based on event-triggered strategy is concerned.Firstly,the corresponding adaptive fault-tolerant controller and parameter updated laws are constructed to effectively compensate the influence of actuator faults and parameter uncertainty on the system.Secondly,the event-triggered control strategy based on relative threshold method is considered to be applied to the design of the adaptive fault-tolerant controller.Finally,the stability of the system is analyzed based on Lyapunov theory,and the effectiveness of the control scheme is verified by simulation.In Chapter 3,the fuzzy event-triggered fault-tolerant control scheme is proposed for the nonlinear system with unknown control direction.Firstly,the virtual controllers and the adaptive updated laws are constructed,and the unknown nonlinear functions are approximated by FLSs.Secondly,Nussbaum function is introduced in the design of event-triggered adaptive fault-tolerant controller,which can effectively avoid chattering phenomenon.Finally,the scheme is designed to ensure that the closed-loop signal is uniformly final bounded within a given compact set and the simulation results show the effectiveness of the control scheme in this chapter.In Chapter 4,the finite-time fuzzy event-triggered fault-tolerant control for a class of nonlinear pure-feedback systems is discussed.Firstly,the theoretical knowledge of differential mean value theorem is used to deal with the nonaffine function in pure-feedback systems.Secondly,the finite-time event-triggered fault-tolerant controller is constructed by using the general approximation capability of FLSs.Different from the design of triggering mechanism in Chapter 2,this Chapter introduces the non-negative decreasing function of tracking error in triggering threshold,which makes the triggering effect more obvious.Finally,the simulation results show that the design of the controller so that the closed-loop signals are uniformly bounded and the output of the system can converge to a small neighborhood of the reference signal in finite time,which further verifies the effectiveness of the control method proposed in this Chapter.Finally,the main work is summarized and the future research direction is prospected.