Adaptive fuzzy reliable tracking control for a class of uncertain nonlinear time-delay systems with abrupt non-affine faults

Abstract

This paper investigates the problem of approximation-based adaptive reliable tracking control for a class of uncertain nonlinear strict-feedback systems. The considered system is with unknown time delays and abrupt non-affine nonlinear faults. To eliminate the effect of unknown time delays, the finite covering lemma and fuzzy logic systems are utilized, and the traditional Lyapunov–Krasovskii function is abandoned. With the help of mean-value theorem, the non-affine nonlinear faults are decoupled for the strictness of system. Based on the property of Nussbaum function, the problem of unknown control directions and control gains is solved. Finally, a novel adaptive fault-tolerant control scheme with the feedback information of not only the current states but also the past states is designed. It is guaranteed that all the signals in the closed-loop system are semi-global uniformly bounded and the tracking error converges to a small neighborhood of the origin. Simulation results from a practical example of isothermal continuous stirred tanks reactors are given to demonstrate the effectiveness of the proposed control scheme.