Robust Fault Detection Scheme for Asynchronous Switched Systems via Sliding Mode Observer

This work studies the fault detection problem for continuous-time asynchronous switched systems. For residual signal generation, we design a fault detection sliding mode observer such that residual characterizes the fault sensitivity level by H_ performance, and its robustness to process disturbance is determined by H_∞ performance. Specifically, the challenge entails addressing the phenomenon of asynchronous switching between the controlled object and the observer, where there is a delay between the switching of the subsystems and the observer. A piece-wise Lyapunov function and average dwell time approach are applied to resolve the asynchronous switching stability within matched and unmatched periods. A feasible solution is derived based on linear matrix inequalities. For effective fault detection, a residual evaluation scheme is provided with a threshold. Finally, simulation results on a buck-boost converter are furnished to validate the usefulness of the proposed approach.