Adaptive Fuzzy Finite-Time Output-Feedback Fault-Tolerant Control of Nonstrict-Feedback Systems Against Actuator Faults

In this article, the finite-time fault-tolerant control (FTC) problem is investigated for uncertain nonlinear nonstrict-feedback systems. The nonstrict-feedback nonlinear system considered in this article contains unmeasured states, unknown control directions, unknown nonlinear dynamics, and actuator faults (both lock-in-place and loss of effectiveness). To realize the control objective, fuzzy-logic systems are used to approximate the unknown nonlinear functions, and a high-gain fuzzy state observer is developed. By using the Nussbaum function technique and combining with the adaptive backstepping control design, a fuzzy adaptive finite-time output-feedback FTC scheme is proposed. It is proved that the closed-loop system is practical finite-time stable (PFTS), and the system output can track a given reference signal. Simulation and comparison results further show the effectiveness of the proposed control strategy.