Robust Fault Detection for Networked Control Systems with Long Time Delays

Considering a class of networked control systems with long time delays and unknown interference inputs, the robust fault detection is carried out when the control and output delays are both present. The robust fault observer is constructed based on discrete switched systems. And a linear matrix inequality gives the stability condition of this observer. Moreover, the fault detection threshold is selected with solving the minimization problem involving a linear matrix inequality constraint. In this way, the robustness and sensitivity of fault detection is enhanced. Finally, an illustrative example is given to demonstrate the effectiveness of the proposed method.