Fuzzy Fixed-Time Fault-Tolerant Control of Uncertain Nonlinear Systems with Non-affine Faults and Its Application in Manipulator Systems

This paper aims to solve two challenging problems in fuzzy control: the complexity explosion caused by iterative derivation of the virtual control laws in design process and the fuzzy adaptive feedback stability for a class of uncertain nonlinear systems. Firstly, the difficulty in backstepping control design for high-order nonlinear systems is solved by combining adding a power integrator method with the dynamic surface control technique and using the fuzzy logic system to approximate unknown nonlinear functions. Then, the non-affine fault of system states and control output can be transformed into a nonlinear one with unknown parameters. The proposed control strategy not only drives the tracking error to converge to an adjustable region of the origin within a fixed time, but also maintains the stability of the closed-loop systems. An advantage is that the convergence time does not depend on the initial state. Finally, the stabilization of a manipulator system is investigated to demonstrate the effectiveness of the control scheme.