Fast and Near-Optimal Guidance for Docking to Uncontrolled Spacecraft

This paper proposes a guidance scheme for autonomous docking between a controlled spacecraft and an uncontrolled tumbling target in circular orbit. The onboard trajectory planning consists of a direct optimization method based on the inversion of the system dynamics. The trajectory components of the controlled spacecraft are imposed by using polynomial functions. Some of the polynomial coefficients are constrained to satisfy path constraints, whereas the remaining coefficients are varied parameters to be optimized. The optimal control problem is converted into a nonlinear programming problem by inverting the system dynamics. The proposed guidance scheme, based on the closed-loop implementation of this optimization problem, is applied to several scenarios. The resulting trajectories closely match the solutions of the correspondent optimal control problems. The guidance scheme is shown to perform precise maneuvers in most maneuvering situations, even in the presence of orbital perturbations. The sensitivity...