Uncertain nonlinear time-delay system adaptive fuzzy PI sliding tracking control

Abstract

In order to deal with large and fast external disturbance, system uncertainties and system time delay, an adaptive fuzzy controller constructed by time delay fuzzy logic system (TDFLS) is proposed for unknown nonlinear time-delay systems which are infinite dimensional in nature. An adaptive time delay fuzzy logic system is used to approximate the unknown time delay system functions, in the meantime proportional integral (PI) sliding mode controller is designed to attenuate chattering problem resulting from the fast and large external disturbance. Based on the Lyapunov theory of stability, the free parameters of the adaptive fuzzy controller and PI controller coefficients can be tuned on-line by output feedback adaptive laws which are derived from tracking and approximation errors. The simulation results show that not only the chattering phenomena can be attenuated but also the prescribed tracking performance can be preserved by the advocated control scheme.