Approximation-Free Attitude Fault-Tolerant Tracking Control of Rigid Spacecraft With Global Stability and Appointed Accuracy

For tumbling or noncooperative targets in space missions, the prior knowledge of the target trajectory is unknown, which leads to the property of prescribed tracking accuracy with assigned settling time hard to achieve. In addition, the unknown inertia characteristics and the presence of actuator faults will also reduce the robustness of the existing spacecraft control methods. To overcome these difficulties, a new approximation-free attitude tracking control scheme of spacecraft with unknown dynamics, external disturbance, and actuator fault is proposed. For the designed controller, no inertia matrix is used, and no approximation-based or adaptive method is applied. Besides, it is rigorously proved that the developed control theory can also ensure that tracking error converges to the prescribed accuracy in appointed time even when the actuator fault occurs. Furthermore, a modified tuning function is used to relax the constraint of the initial value, which ensures the global stability of the closed-loop system. Simulation results verify effectiveness of the proposed method.