Robust Fault Detection for State-delay Systems Based on H_∞ Filter

A robust fault detection scheme is proposed for a class of time-delay systems with unknown inputs. The fault detection filter is designed by using H_∞ control theory. The reference model is introduced to formulate the generalized residual, and the robustness of residual to unknown inputs and the sensitivity to fault signal are reflected by L _2-gain. The robustness of the residual to the unknown inputs is proved and then linear matrix inequality (LMI) approach is used to derivate the existence conditions of the robust fault detection filter(RFDF) for the time-delay systems, independently of time delay. Finally, an example is given to demonstrate the effectiveness of the proposed approach.