Finite-time attitude control for spacecraft with actuator misalignment

A novel attitude stabilization control scheme is presented for spacecraft subject to disturbance and actuator misalignment. A sliding-mode based observer is first designed to reconstruct disturbance torque and the torque introduced by actuator misalignment on-line. It is proved by Lyapuonv analysis that precise reconstruction with zero observer error is achieved in finite time. Together with the system states, the reconstructed information is then used to synthesize a nonlinear controller. The closed-loop attitude system is finite-time stable. The attitude and the angular velocity are stabilized in finite time. Simulation results of an application to a spacecraft are presented to demonstrate the effectiveness of the proposed control scheme.