Robust Fault Detection and Isolation for Uncertain Switched Systems under Asynchronous Switching with Adaptive Threshold

Abstract

The problem of fault detection and isolation for uncertain continuous-time linear switched systems in the presence of disturbances and noise is addressed in this paper. A robust residual generator is proposed which is based on asynchronously switching filters, where “asynchronous” means there is a lag between switching of filters and subsystems. To address the issue, fault detection problem is formulated as mixed H-/H∞ filtering problem. In proposed H-/H∞ technique, the effect of fault on residual signal is fixed to some maximum possible index and then influence of unknown inputs (disturbances and noise) on residual is minimized. In addition proposed filter has prominence of having fault isolation capability along with fault detection. To improve the fault detection capability adaptive threshold is set which takes into account local disturbance levels, the current operational mode and applied input signal. Then, solution is designed for boost converter switched system application and simulations are presented to illustrate the efficacy of the proposed framework.