Fuzzy adaptive robust fault-tolerant control for uncertain nonlinear systems based on small-gain approach

In this paper, fuzzy adaptive robust control approaches and fault-tolerant algorithms are proposed for single-input-single-output (SISO) nonlinear systems with the nonlinear uncertainties, actuators faults, unmodeled dynamics and dynamic uncertainties. The unknown nonlinear functions are not linearly parameterized and have no prior knowledge of the bounding. Fuzzy logic systems are used to approximate the nonlinear uncertainties and the unknown fault function and by combining backstepping technique with a small-gain approach, a stable fuzzy adaptive backstepping robust fault-tolerant control has been proposed. It is proven that the proposed fuzzy adaptive control approach can guarantee that all the solutions of the closed-loop systems are semi-globally uniformly ultimately bounded. The effectiveness of the proposed approach is illustrated form simulation results.