This paper studies the problem of fault-tolerant control for the drag-free satellite subject to actuator failures and input saturations. Particularly, a new Kalman filter-based model predictive control method for the drag-free satellite is proposed. Based on the developed dynamic model and the Kalman filter strategy, a new fault-tolerant design scheme is presented for the challenging situation where the satellite is subject to measurement noise and external disturbance. With the designed controller, the robustness of the system can be guaranteed, and the problem caused by actuator constraints and faults can be solved. Finally, the correctness and effectiveness of the proposed method are verified by numerical simulations.

This paper proposes a robust control allocation for the capture control of the space inertial sensor’s test mass under overcritical conditions. Uncertainty factors of the test mass control system under the overcritical condition are analyzed first, and a 6-DOF test mass dynamics model with system uncertainty is established. Subsequently, a time-varying weight function is designed to coordinate the allocation of 6-DOF generalized forces. Moreover, a robust control allocation method is proposed to distribute the commanded forces and torques into individual electrodes in an optimal manner, which takes into account the system uncertainties. This method transforms the robust control allocation problem into a second-order cone optimization problem, and its dual problem is introduced to simplify the computational complexity and improve the solving efficiency. Numerical simulation results are presented to illustrate and highlight the fine performance benefits obtained using the proposed robust control allocation method, which improves capture efficiency, increases the security margin and reduces allocation errors.