Adaptive fault-tolerant control of a class of nonaffine nonlinear systems with mismatched parameter uncertainties and disturbances

This paper studies the problem of robust adaptive fuzzy fault-tolerant tracking control for a class of nonaffine nonlinear systems with mismatched parameter uncertainties, external disturbances and actuator faults. Without using complicated backstepping technique, a direct adaptive fuzzy tracking control approach is used to achieve the fault-tolerant control objective. First, to overcome the obstacle for the nonaffine nonlinear term with actuator faults, a nonaffine compensation term is constructed to eliminate the effect of the nonaffine fault parameters. Then, based on the implicit function theorem and the mean value theorem, a novel design scheme that converts the nonaffine system into the corresponding affine system is developed, and two effective fuzzy logic systems, which are introduced to approximate the appropriate nonlinear functions, are constructed to compensate the effect on mismatched parameter uncertainty and disturbance, respectively. Furthermore, with the help of Lyapunov stability analysis, it is also proved that all the closed-loop system error signals are uniformly ultimately bounded. Finally, a numerical example is given to verify the efficiency of the presented adaptive fuzzy fault-tolerant tracking design approach.