On the use of free-floating space robots in the presence of angular momentum

Free-floating space manipulator systems include at least one manipulator mounted on an unactuated spacecraft. It is known that such systems exhibit nonholonomic behavior due to angular momentum conservation. In this paper, the initial angular momentum of the system is not assumed to be zero and its influence on system behavior is studied. In contrast to the case of zero initial momentum, in the presence of momentum, the manipulator end effector in general cannot remain at a given location for indefinite time. The paper studies the conditions under which this is possible, rendering the end-effector immune to angular momentum accumulation. The relevant kinematics and dynamics are studied in 2D and 3D systems, and workspace subsets, where the end effector can remain fixed, are identified. Examples illustrate the validity of the results.