Adaptive Fault-Tolerant Control For A Class Of Lower Triangular Nonlinear System

Owing to the rapid development of science and technology,the modern control systems have become very complicated and sophisticated.Not only is the system affected by external disturbances,but its internal and external components may also malfunction.Under this circumstances,how to design a reasonable controller to keep the system running safely and stably and achieve the desired control objectives is one of the key and difficult problems in the current control field.Based on the existing results and Lyapunov stability theory,this paper studies adaptive fault-tolerant control for a class of lower triangular uncertain nonlinear systems,to explore the roles of adaptive fault-tolerant control technology in automatic control system.The main research contents of this paper are shown as follows:Chapter 1 introduces the research background and the related overview of fault-tolerant control method and adaptive control theory,and some of the basics knowledge of this article are given in chapter 2.Chapter 3 studies the decentralized adaptive fuzzy fault-tolerant control problem for a class of uncertain large-scale nonlinear systems with actuator failures,mismatching parameter uncertainties and multiple time delays.By constructing a proper nonlinear function and using fuzzy logic systems(FLSs)to deal with interconnection term and mismatching parameter uncertainties.Based on the online estimation for the unknown upper bound information of multiple time delay disturbance function and the time-varying stuck fault,the decentralized adaptive fuzzy H_?fault-tolerant controller with corresponding adaptive updated laws is designed.Moreover,based on Lyapunov stability analysis,it is shown that all the close-loop signals are uniformly bounded and the states of the subsystems can converge to a small neighborhood of the origin after occurs faults.Finally,the simulation results verify the effectiveness of the proposed method.In chapter 4,the designed problem of finite-time adaptive fault-tolerant control for a class of uncertain nonlinear systems with actuator failures is considered.By using of the strict back-stepping method,the finite-time virtual controller and corresponding adaptive laws are designed in each step.In the last step,a finite-time adaptive fault-tolerant controller is presented,the effects of actuator failures and unknown parameter uncertainties on the systems are effectively eliminated.Finally,two examples are given to verify the proposed method.By comparing with the classical adaptive fault-tolerant control method,the superiority of the proposed method is illustrated.From the simulation results it can be seen that the tracking error can converge to a smaller neighborhood of origin by using the finite-time adaptive fault-tolerant control method and all signals of the close-loop systems are bounded,the effectiveness of the proposed scheme in this chapter is further illustrated.Chapter 5 summarizes the results of the dissertation and and pointed out the future research.