Practical Prescribed-Time Attitude Control for Flexible Spacecraft Based on Disturbance Observer

The paper investigates the practical prescribed-time attitude stabilization problem for a flexible spacecraft with unknown disturbances. By introducing a time-varying function, a prescribed-time disturbance observer is designed to estimate the unknown external disturbances. With the aid of the backstepping control method and fully actuated system approach, a practical prescribed-time controller can be proposed by using the disturbance estimation. Theoretical analysis and simulation results prove that the attitude of the flexible spacecraft under the proposed control scheme can converge to prescribed precision within prescribed time.