Design guidelines for a space manipulator for debris removal

This paper deals with the main drivers for the design of a space manipulator aimed to debris removal. At the scope, the different phases of a debris removal mission are considered, starting from the parking orbit where the chaser spacecraft waits for the call-on duty, the approach to the target, the grasping and finally the dismissal of the captured objects. The requirements of each phase, in terms of the needed accuracy of the relative navigation sensors, manipulators' joint control torques and thrusters force are analysed. The number of robotic arms, the number of joints of each arm, and the torque level that each joint motor should supply are determined mainly by two phases: the grasping phase and the de-orbit phase. During the grasping, the tumbling target must be tracked with a large degree of robustness, and, to this aim, a redundant manipulator must be designed, so that its workspace can be as large as possible. On the other hand, increasing the degrees of freedom of a robotic a

This paper deals with the main drivers for the design of a space manipulator aimed to debris removal. At the scope, the different phases of a debris removal mission are considered, starting from the parking orbit where the chaser spacecraft waits for the call-on duty, the approach to the target, the grasping and finally the dismissal of the captured objects. The requirements of each phase, in terms of the needed accuracy of the relative navigation sensors, manipulators' joint control torques and thrusters force are analysed. The number of robotic arms, the number of joints of each arm, and the torque level that each joint motor should supply are determined mainly by two phases: the grasping phase and the de-orbit phase. During the grasping, the tumbling target must be tracked with a large degree of robustness, and, to this aim, a redundant manipulator must be designed, so that its workspace can be as large as possible. On the other hand, increasing the degrees of freedom of a robotic arm means higher complexity and realization costs; a trade-off is therefore outlined. The number of arms depends instead on the final de-orbit phase, in which the powerful apogee motor of the chaser satellite is ignited, in order to change the composite system (chaser + target) orbit. The thrust, applied on the chaser, is transferred into the target by means of the robotic arms: it is shown that a single robotic arm could not be sufficient to withstand the high solicitations acting during this phase. The joint torques required to keep the robotic arm into position end up to be very high too, and the joint motors must be designed accordingly to provide the maximum expected values.