Trajectory Optimization for Dynamic Grasping in Space Using Adhesive Grippers

Spacecraft equipped with gecko-inspired dry adhesive grippers can dynamically grasp objects having a wide variety of featureless surfaces. In this paper we propose an optimization-based control strategy to exploit the dynamic robustness of such grippers for the task of grasping a free-floating, spinning object. First, we extend previous work characterizing the dynamic grasping capabilities of these grippers to the case where both object and spacecraft are free-floating and comparably sized. We then formulate the acquisition problem as a two-phase optimization problem, which is amenable to real time implementation and can handle constraints on velocity, control, as well as integer timing constraints for grasping a specific target location on the surface of a spinning object. Conservative analytical bounds for the set of initial states that guarantee feasible grasping solutions are derived. Finally, we validate this control architecture on the Stanford free-flyer test bed—a 2D microgravity test bed for emulating drift dynamics of spacecraft.