Monitoring-Based Adaptive Fault-Tolerant Control for Uncertain Nonlinear Systems With Gradual Actuator Deactivation

This article proposes a monitoring-based adaptive fault-tolerant control (FTC) scheme for a class of uncertain nonlinear systems with a backup actuator. Different from the existing switching-based FTC schemes, an actual issue of gradual actuator deactivation is first taken into consideration, i.e., faulty actuator cannot be deactivated immediately. To reconfigure the controller, a method of estimating the upper bound of the nonlinearity caused by the gradual deactivation is used, and modified shifting functions are introduced to improve the system transient performance. Once an actuator failure is detected by the integrated monitoring function, the reconfigured controller together with the backup actuator can ensure that the tracking error is limited to the prescribed performance within a preset time. Simulation on an aircraft system and experiment on a motor-driven disk have been demonstrated.