Output Feedback Attitude Tracking for Spacecraft Under Control Saturation and Disturbance

Abstract

This paper proposes a class of velocityfree attitude stable controller using a novel finitetime observer for spacecraft attitude tracking, which explicitly takes into account control input saturation to assure fast and accurate response and to achieve effective compensation to the effect of external disturbance as well. First, a novel semiglobal finitetime convergent observer is proposed to estimate the angular velocity in a finitetime under external disturbance. Then, a simple global output feedback controller is proposed by adoption of the designed finitetime observer. Rigorous proofs show that the proposed observer can achieve the finitetime stability and the controller rigorously enforces actuator magnitude constraints. Numerical simulations illustrate the spacecraft performance obtained using the proposed controller.