Fault tolerant control for satellites with four reaction wheels

The authors propose a simple and effective fault tolerant control method for satellites with four reaction wheels. The proposed method is based on dynamic inversion and time-delay control theory. Faults of reaction wheels are modeled as additive and multiplicative unknown dynamics, which are estimated by using one-step previous state information and canceled out by the estimated values. Therefore, this method can accommodate faults rapidly without any explicit reconfiguration. Numerical simulations demonstrate the performance of the proposed method by comparing with a conventional proportional-derivative control.