Robust fault detection for network-based system with time-varying delay

For network-based system with time-varying delay, the fault detection filter design approach based on robust H_∞ theory was proposed. The robust H_∞ fault detection problem was converted into design parameter matrices of the filter which guarantees the internal stability and the robust H_∞ performance index. Faults were detected based on the residual error evaluation function and the fault threshold. It was assumed that the time-varying delay was bounded and the upper and lower bounds were known. The delay-dependent Lyapunov-Krasovskii functional was chosen to derive the delay-dependent condition for the existence of the fault detection filter. The parameters of the corresponding fault detection filter were obtained by solving the delay-dependent condition. Under bounded control inputs, external disturbances and fault signals, the fault detection filter can guarantee the boundedeness of the resultant residual error. The effectiveness of the proposed approach was demonstrated by the application to the highly maneuverable technology (HiMAT) vehicle flight control system.