Design of Fixed-Time Extended State Observer for Spacecraft Attitude Tracking

This paper investigates the problem of attitude tracking control for rigid spacecraft with high precision requirement. Utilizing the fixed-time control theorem, a new fixed-time extended state observer (FTESO) is designed to solve the impacts from overall parameter uncertainties and external disturbances. Using the proposed FTESO, a finite-time controller is then developed based on barrier Lyapunov function (BLF). The control scheme is continuous and nonsingular, and it can guarantee that the attitude tracking error converges to a small origin within finite-time while satisfying attitude constraint. Finally, simulation results are employed to demonstrate the effectiveness of the developed control algorithm.