Fuzzy adaptive output feedback control for uncertain nonlinear systems with unknown control gain functions and unmodeled dynamics

Abstract

In this work, the fuzzy adaptive robust output feedback control issues are investigated for single-input single-output (SISO) strict-feedback nonlinear systems. The controlled systems under consideration of this paper contain the unknown control gain functions, unmodeled dynamics and immeasurable states. The unknown nonlinear functions are be approximated by utilizing the fuzzy logic systems, and the immeasurable states are estimated by constructing a new fuzzy state observer. In order to handle the unknown control gain functions and the unmodeled dynamics problems, the Logarithm Lyapunov functions are constructed, under which a new fuzzy adaptive robust output feedback control scheme is proposed by using the adaptive backstepping control design technique and a dynamical signal function. The designed fuzzy adaptive control algorithm can ensure that the closed-loop system is semi-globally uniformly ultimately boundedness (SGUUB) and has the robustness to the unmodeled dynamics. Finally, a simulation example is considered to illustrate the availability of the designed controller.