Autonomous rendezvous and docking of spacecraft under 6-DOF motion constraints

This paper addresses the coupled rotation and translation control problem for final phase proximity operations of spacecraft autonomous rendezvous and docking. During the proximity phase, some important motion constraints are considered. On the one hand, to track the target spacecraft, the sensor system of the chaser spacecraft is required to continuously point toward the target; on the other hand, for safety concerns, the chaser also needs to satisfy approaching path constraints. A special dual-quaternion based artificial potential function (APF) is presented to encode information regarding these motion constraints, and then a novel six-degree-of-freedom control method is proposed to ensure the chaser can finally arrive at the docking port of the target with the desired attitude while strictly complying with all specified constraints. Stability of the closed-loop system is demonstrated by the Lyapunov-based method along with the convex property of the proposed APF. Simulation results of a prototypical spacecraft rendezvous and docking mission are provided to illustrate the effectiveness of the proposed method.