Modified sliding control for tumbling satellite capture with robotic arm

The capability to capture uncooperative, tumbling space objects is a critical requirement for any on-orbit servicing or space debris removal system. For successful capture, the chaser spacecraft must be able to navigate to the target and reach the desired grasping or docking feature. In order for the forces during grasping on both the grasping mechanism and the target object not to exceed structural limits, the chaser must perform formation flight with low relative velocity for the duration of the capture process. This paper presents a robust control approach for the capture of an uncooperative, tumbling target based on the Clohessy-Wiltshire equations of motion. As the capture maneuver must be tuned to accommodate the capabilities of the capture mechanism, a conceptual design for a possible grasping mechanism is also presented. The capabilities of this mechanism help define the constraints of the numerical simulations of the capture maneuvers.