Development of tele-operation control for a free-floating robot during the grasping of a tumbling target

This paper addresses the singularities avoidance problem while performing a grasping maneuver in teleoperation with a manipulator mounted on a free-floating spacecraft. Firstly, the independence of the singularities of the end-effector Jacobian of a generic free-floating system from the inertial parameters of the last link is demonstrated. Secondly, the possibility to represent all the singularities in the Cartesian space for a freefloating system provided with three reaction wheels is shown. Finally an optimization algorithm is presented, which provides the optimal spacecraft initial Cartesian position and attitude, to allow the operator to keep a trajectory in the vicinity of the nominal motion while satisfying operational constrains as long as possible.