Adaptive saturated control for spacecraft rendezvous and docking under motion constraints

This paper investigates the problem of position tracking and attitude synchronization for spacecraft rendezvous and docking with a tumbling target, in which kinematic couplings, unknown disturbances, motion constrains, and input saturation are considered. A novel artificial potential function (APF) is developed to encode both three-dimensional pose information and two-dimensional image information regarding path constraint and field of view constraint, respectively. By integrating the APF into the sliding mode technique, an adaptive control strategy is proposed to realize the arrival of the chaser at the docking port without any risk of collision or loss of target features. In addition, a linear anti-windup compensator is introduced to compensate for the input saturation effect. Uniformly ultimately bounded of the closed-loop system is guaranteed through Lyapunov analysis. A specific simulation scenario of docking with the defunct satellite Envisat is created to demonstrate the effectiveness and robustness of the proposed control strategy.