On Manipulator Posture Planning for Large Force Tasks

In this paper, we study the problem of large force/torque application using robotic systems with limited force/torque actuators. For such systems, the available workspace may be smaller than its reachable workspace. It is shown that redundancy increases the force capability and workspace of a robotic system. To plan redundant manipulator postures during force tasks, a new method based on a min-max optimization scheme is used. Unlike other norm-based methods, the proposed one guarantees that no actuator capabilities are exceeded, and that the required force/torque of the most loaded actuator is minimized. Examples that demonstrate the validity and usefulness of the proposed method are included.