Nonlinear Fuzzy Adaptive Switching Control Design And Stability Analysis

This thesis considers several classes of uncertain switched nonlinear systems,and the problems of switching control design and state constraint control design are studied by the switching barrier Lyapunov functions.In the backstepping framework,adaptive fuzzy state feedback constraint switching controllers and switching laws are proposed by using fuzzy logic system theory and average dwell time.Based on Lyapunov function,stability and feasibility of the closed-loop systems are verified.The main work of this thesis is as follows:(1)The control design and “explosion of complexity” problems for a class of non-strict feedback nonlinear systems with full-state constraints and switching signal were considered.In the framework of backstepping design method,by combing log-type barrier Lyapunov function(BLF)with adaptive fuzzy control theory,the fuzzy adaptive constraint switched control strategy and switching laws are given.The adopted dynamic surface control technology effectively avoids the “explosion of complexity” problem which occurs during the control process based on backstepping technology.Based on the Lyapunov theory and the average dwell time method,it is proved that the designed adaptive fuzzy dynamic surface constraint switched control strategy can ensure the stability and track performance of the controlled system,and guarantee that all states do not violate their constrained bounds.(2)For a class of strict feedback switched stochastic nonlinear systems with unstable inverse dynamics,the design problem for state feedback fuzzy adaptive constraint switched control is studied.In the framework of bacskstepping design algorithm,a fuzzy adaptive switched controller is designed by using stochastic log-type BLF.Based on ?Ito lemma,linear matrix inequality(LMI)method and Lyapunov theory,it is proved that the proposed control strategy ensures the excellent tracking performance of the controlled system,and the states of the controlled system do not violate their prescribed constrained bounds.Morever,the proposed control method guarantees that the unstable inverse dynamics are stable,and signals of the closed-loop system are bounded in probability.(3)For a class of non-strict feedback switched nonlinear systems with full prescribed performance and switching signal,the finite-time fuzzy adaptive control and switched control design problems were investigated.In the framework of adaptive backstepping technology,by using the full prescribed performance finite time method and nonlinear filter,a finite-time fuzzy adaptive switched control stratety is proposed,which effectively eliminates the “explosion of complexity” that exist in the backstepping design process.Combined with the Lyapunov theory,the application of the design algorithm to the controlled object is proved to be reliable.To determine the settling time,a specified performance function is introduced.Based on the prescribed performance theory,it is not only necessary to ensure that the tracking error and the virtual error reach the equilibrium point within a finite-time,but also to limit them to the specified boundary.(4)In order to further verify the effectiveness and feasibility of the proposed control methods and theories,corresponding numerical simulation examples are given.