An inverse dynamics approach to the guidance of spacecraft in close proximity of tumbling debris

This paper proposes a trajectory planning method based on polynomial shaping, applied to the docking scenario in the framework of an Active Debris Removal mission. A tumbling, uncooperative target with an asymmetric inertia tensor is considered. Closed-form solutions of the target's motion are obtained from an approximated axisymmetric model, which are incorporated to the trajectory planning algorithm. The close approach and docking strategy is designed in three different segments, in order to enhance the safety of the manoeuvre. Fuel is optimised amongst the class of polynomial trajectories considered, and thrust constraints are taken into account via inverse dynamics. The trajectory planning algorithm is implemented in a closed-loop guidance scheme, which simulations show to be robust to large sensor sample times and external disturbances.