Robust Fault Detection and Diagnosis for a Multiple Satellite Formation Flying System Using Second Order Sliding Mode and Wavelet Networks

This paper presents a robust fault detection and diagnosis (FDD) scheme for abrupt and incipient faults in a class of nonlinear dynamic systems. A nonlinear observer which synthesizes second order sliding mode techniques and wavelet networks is proposed for online monitoring. The second order sliding mode is designed to eliminate the effect of system uncertainties on the state observation. Moreover, a bank of wavelet networks is constructed to isolate and estimate faults. Theoretically, the convergence of the state estimation using the second order sliding mode is analyzed. An adaptive algorithm is adopted to update the parameters of the wavelet networks, and its convergence is investigated as well. Finally, this robust FDD scheme is applied to a multiple satellite formation flying system, and simulation results illustrate its effectiveness.