Fault detection for networked control systems with control delays

Considering a class of networked control systems with long time delays, the fault detection is carried out when the control delays are present between the controller and the actuator. Firstly, a modeling approach of networked control system is presented, and the state estimate error equation is given by constructing the fault observer. And then, based on Lyapunov stability theory, a linear matrix inequation gives the stability condition of this observer. When the system is normal, if the given inequality condition is satisfied, the observer system is stable. When a fault is present, the observer residual can change rapidly and detect the occurrence of the fault. Finally, an illustrative example is given to demonstrate the effectiveness of the proposed method.