Fault-tolerant attitude control of spacecraft by using robust adaptive method

In this paper, an attitude control scheme based on MRPs (The Modified Rodrigues Parameters) for a spacecraft subject to external disturbances and partial loss of three-axis effectiveness is proposed. First of all, the author establishes the dynamic model of spacecraft and the attitude kinematic equation based on MRPs, and the faults of the angular momentum exchange devices are modeled as multiplicative unknown dynamics. Then, the desired angular velocity of a spacecraft is derived from the relationship between the desired attitude and the real-time attitude of a spacecraft. Next, an observer is designed to estimate the fault factor of the spacecraft. By using the estimated fault factor, a robust controller based on indirect adaptive method is designed to achieve the attitude maneuver control. Therefore, this method can handle the faults of actuators without using the fault detection and diagnosis (FDD) mechanism. Simulation results are provided to verify the performance of the proposed scheme.