Command filter-based adaptive fixed-time fault-tolerant control for stochastic nonlinear systems with actuator hysteresis

In this paper, an adaptive fault-tolerant fixed-time control problem is considered via command-filter technique for stochastic nonlinear systems with sensor fault and actuator hysteresis. With the application of command-filtering technique, a novel command-filter compensate mechanism is designed, which implies that the improved control scheme not only eliminates "the explosion of complexity" but also realizes the compensate signal is bounded within fixed-time interval. The unavailability of state variables caused by sensor fault is solved by applying parameter separation and regrouping approach. Meanwhile, an adaptive auxiliary signal is designed to cope with the backlash-like hysteresis phenomenon, which can avoid singularity, reduce chattering, and facilitate controller design. Combining backstepping technique and Lyapunov stability theorem, an adaptive fault-tolerant control approach is developed, which can guarantee all closed-loop signals remain semi-globally practical fixed-time stable (SGPFS) in probability. The validity of the proposed strategy is illustrated by simulation examples.