Fault diagnosis of linear time-varying system based on high gain / adaptive compensation sliding mode observer

The problem of fast diagnosis in the presence of the control surface and sensor of flight control system come up with fault together is researched based on the outer loop and inner loop cascade robust observer. An auxiliary output vector is proposed so that the observer matching condition is satisfied, a new augmented system includes the surface and sensor fault is established. The high gain sliding model observer is designed to estimate the system output exactly in the outer loop, and an adaptive compensation sliding model observer is proposed in the inner loop. The sliding model improve the robustness of the observer, and the adaptive compensation component makes the estimation for the control surface accurately, then the fault could be diagnosed fleetly. The effectiveness of the proposed methods is proved by the numerical simulation.