Teleoperation of Free-floating Space Manipulator Systems

Free-flying space robotic devices, in which manipulators are mounted on a thruster-equipped spacecraft, will assist in the construction, repair and maintenance of satellites and future space stations. Operation in a free-floating mode, in which spacecraft thrusters are turned off, increases a system’s life. The teleoperation of free-floating systems is complicated due to the dynamic coupling between a system’s manipulator and its spacecraft. Controlling such a system using visual feedback is not straightforward, especially when the task is to move the end-effector with respect to an inertially fixed target. In addition, free-floating systems are subject to path-dependent Dynamic Singularities, which restrict the paths by which Path Dependent Workspace points can be reached. These characteristics can result in increased operator burden during system teleoperation. A teleoperation planning system to assist the operator of a free-floating space robot is presented. Given an initial and a target end-effector location, and an optional connecting path, this system examines the feasibility of reaching the target from the initial location. If a problem is detected, the system proposes an alternative feasible path. An example demonstrates the value of such a teleoperator planning aid.