Predefined-Time Disturbance Estimation and Attitude Control for Rigid Spacecraft

In this brief paper, a disturbance observer-based predefined-time attitude stabilization strategy is proposed for rigid spacecraft with external disturbances and inertia uncertainties. The disturbance rejection is achieved by constructing a predefined-time nonlinear disturbance observer (PTNDO), and the fast and accurate convergence of disturbance estimation error is ensured. By establishing a novel predefined-time stability criterion, a predefined-time attitude backstepping controller is developed, such that the spacecraft attitude can converge to the neighborhood near origin within an expected settling time. Unlike most of the existing predefined-time design approaches, the singularity problem is directly avoided in this paper without introducing any piecewise continuous functions or quadratic-fraction functions. Finally, numerical simulations are conducted to verify the effectiveness of the proposed strategy.