On-line Auxiliary Input Signal Design for Active Fault Detection and Isolation Based on Set-membership and Moving Window Techniques

This paper presents an on-line auxiliary input signal design strategy based on set-membership and moving window techniques to deal with the problem of active fault detection and isolation. The goal of active fault detection and isolation is to design an auxiliary input signal, such that the nominal system output set and faulty systems output sets are separated each other after injecting the input signal. In this paper, the output sets are characterized by ellipsoids. First, an extended model of the system based on moving window technique is constructed, then an auxiliary input signal is calculated on-line based on the equivalent model. As the energy of the auxiliary input signal is restricted minimum to decrease the influence of the signal on the system, the design condition of active fault detection and isolation is transformed into an optimal problem. Furthermore, the fault is isolated by judging the actual system output belongs to which output ellipsoid of the faulty models, or determining the probability of the system output is in which faulty model when the output ellipsoids of faulty models are intersecting. Finally, numerical simulations illustrate the feasibility and effectiveness of the proposed approach.