Research On Adaptive Control Algorithm For Discrete-time Switched Nonlinear Systems

Switched systems are hybrid systems which consist of a collection of subsystems and a switched signal governing the switching among them.Switched systems have attracted much attention since it can be used to describe a large of physical and engineering systems.As we can see,the most of studies are focused on switched continuous-time systems and many meaningful works haven been framed.However,owing to complexity of the discrete-time switched system,the investigation of switched discrete-time nonlinear systems is relatively somewhat limited.Based on the previous results,this paper is concerned with the problem of adaptive tracing control for discrete-time switched nonlinear,the main contribution of the research work presented in this dissertation are as follows:(1)The adaptive tracking control approach is framed for a class of switched discrete-time nonlinear systems with unknown parameters.Allowable switching law is constructed and the controller is chosen by switched Lyapunov function schema.Adaptive updating control algorithm is a distinct property to control discrete-time nonlinear switched systems.Moreover,we can prove that the closed-loop switched system is uniformly stable and the output tacking error is guaranteed to converge to a small neighborhood of zero.Lastly,an illustrative example is given to demonstrate the effectiveness of proposed approach.(2)The problem of fuzzy tracking adaptive control for a class of discrete-time switched uncertain nonlinear systems with arbitrary switching is addressed.The control problem for a class of discrete-time switched uncertain nonlinear systems is firstly set up by utilizing the fuzzy logic systems to approximate the unknown nonlinear functions and based on the common Lyapunov function method.Meanwhile,the proposed adaptive law algorithm reduces the amount of online adjustable parameters.Based on the techniques above,the fuzzy controllers and the adaptive law are constructed to guarantee that all the signals in the closed-loop system are bounded and the output of systems converges to a small neighborhood of the reference signal.An illustrative example is provided to demonstrate the effectiveness of the proposed approaches.