Adaptive Fault Diagnosis for T–S Fuzzy Systems With Sensor Faults and System Performance Analysis

It is well known that there always exist some level of time delay between fault occurrence and fault accommodation, which is called as the time delay due to fault diagnosis (TDDTFD) in this paper. TDDTFD may cause severe loss of system performance and stability. This paper investigates the TDDTFD's adverse effect on the system performance. First, a fault diagnosis (FD) model is constructed to diagnose sensor faults which integrate time-varying gain and bias faults, where a novel FD algorithm is proposed, which removes the classical assumption that the time derivative of the output error should be known. Meanwhile, the time spent at each step in FD and its analytical expression are derived strictly. Further, the analysis of the system performance degraded by TDDTFD is developed, and the conditions under which the magnitudes of sensor faults should be satisfied such that the state of the faulty system controlled by the normal controller remains bounded during TDDTFD are derived. In addition, the corresponding solutions are proposed to minimize the adverse effect of the time delay. Finally, simulation results of near-space vehicle attitude dynamics are presented to demonstrate the efficiency of the proposed approach.