Adaptive fault-tolerant control for uncertain nonlinear systems with both parameter estimator and controller triggering

Abstract

In this paper, the fault-tolerant control (FTC) problem for a class of nonlinear systems with uncertain parameters and unknown actuator failures is studied. The considered failure number of times is not limited to be finite, and the input-to-state stable assumption is no longer needed. An adaptive FTC scheme is proposed based on event-triggered strategy. A set of event-triggering conditions are designed for not only the controller but also the parameter estimators, with which the parameter estimator-to-controller and controller-to-actuator channels are both event-triggered simultaneously. It is proved that, with our proposed scheme, all the closed-loop signals are globally uniformly bounded, and the system output converges into a compact set which can be made small by appropriately adjusting the design parameters. Also, the Zeno behavior is proved to be excluded. Besides, a modified FTC scheme is designed for the case with finite number of failures, which ensures the asymptotic convergence of system states. Finally, a robot manipulator example is employed to illustrate the effectiveness of the proposed schemes.