Impact estimation of a space robot at capturing a target

Capturing a target by a robot hand in space inevitably causes impulsive forces on the contact points. Such forces possibly give undesirable effects to both spacecraft. The authors´ purpose is to study the relationships between the initial relative velocities of the hand to the target and the resulting contact impulse. The authors consider the effects of the servo stiffness and the desired joint rates for the manipulator control. Using the Laplace transformation, the authors estimate the contact impulse with these effects taken into consideration. From the estimations, it is shown that the joint stiffness increases the effective moment of inertia around its joint and as a result increases the impulsive contact forces. It is also shown that the joint rates are desired to be set as the initial joint rates to relax the contact impulse. Numerical simulations and hardware experiments are also given to validate the authors´ approach