A Multiple-Observer Scheme for Fault Detection, Isolation and Recovery of Satellite Thrusters

The method proposed in this paper aims at automatically detecting, isolating and identifying faults on actuators of a satellite model and also aims at automatically reconfiguring the reference input once the fault has been isolated. The method uses two sliding mode observers to detect and reconstruct the fault. A cusum test on the output of the detection observer triggers a bank of Unknown Input Observers in order to isolate the faulty actuator. The reference input is automatically reconfigured in order to pre-compensate the fault, which makes the satellite capable of fulfilling its mission with the desired performances and good precision. Monte Carlo analysis, based on performance criteria, is carried out to assess the performance of the strategy. The combination of these different types of filters might provide better detection, isolation and identification capabilities than a single filter that would be forced to achieve a trade-off between fast detection and accurate estimation.