Fixed-time Attitude Stabilization for Spacecraft Based on Active Disturbance Rejection Method

This paper mainly investigates the fixed-time attitude stabilization problem of a rigid spacecraft subject to inertia uncertainties and external disturbance. Firstly, a terminal sliding mode surface is constructed to guarantee the fixed time convergence of the attitude independent of initial states. Then, active disturbance rejection control is used to guarantee the states of the spacecraft system reach an arbitrary small vicinity of the terminal sliding mode surface in fixed time. Moreover, to solve the singularity problem in terminal sliding mode control design, an asynchronous switching law is proposed to avoid the singularity. Finally, numerical simulations illustrate the control performance of the proposed control method.