Observer based finite-time control for spacecraft reorientation with multiple constraints

Rigid-body reorientation under attitude constraints has been studied extensively, but few of them take into account the angular velocity constrains which occur frequently in practice. This paper investigates spacecraft reorientation with attitude pointing and angular velocity constraints under external disturbance. A non-singular finite-time observer without chatting is first developed to estimate the external disturbance, ensuring that the estimation error converges to zero within a finite time. Subsequently, by introducing two potential functions, the control objective is transformed into maintaining boundedness of two potential functions. Owing to the potential, the unwinding phenomenon can be avoid during the process of spacecraft attitude maneuvering. Meanwhile, a non-singular finite-time controller is proposed, combining with the observer to improve the control accuracy. Lyapunov stability analysis shows that the proposed controller can guarantee asymptotic convergence of both the attitude error and angular angular velocity error to zero, despite the presence of unknown external disturbance. Numerical simulations are conducted to validate the effectiveness and superiority of the proposed method.