Robust fault reconstruction based on sliding mode observer for a class of uncertain time-varying delay systems: a rocket motor system application

Abstract

In this paper, we present an extended sliding mode observer (SMO) design method for robust actuator fault reconstruction for a class of linear uncertain delayed systems. The uncertainty considered is matched and bounded. In meantime, the time-varying delay is unknown, bounded and affects simultaneously the input and the state of the system. Using the H1 concept and applying the equivalent output error injection idea from previous works in fault detection and isolation (FDI) scheme, the estimate actuator fault signal is designed with the proposed observer by minimising the uncertainty and the time-varying delay effects. Therefore, this problem is solved via a bounded real lemma (BRL) and the linear matrix inequalities (LMIs) optimisation. A rocket motor system is included to illustrate the efficiency of the proposed method. Even, in the presence of the uncertainty and the time-varying delay, the results of the simulation demonstrate that the proposed schemes can successfully estimate the system states and reconstruct the unknown actuator fault.