Large force-task planning for mobile and redundant robots

This paper analyzes the application of large force/torques by robotic systems with limited force/torque actuators. It is shown that such system may be able to apply a force/torque in some configurations only; therefore its useful force workspace is limited. To improve the force capabilities of a system, base mobility and/or redundancy can be employed. A planning algorithm is proposed which results in proper base positioning relative to a large-force quasi-static task. To plan redundant manipulator postures during large force-tasks, a new method based on a min-max optimization scheme is developed. Unlike norm-based methods, this method guarantees that no actuator capabilities are exceeded, and that the force/torque of the most loaded joint is minimized. Examples that demonstrate the validity and usefulness of the proposed methods are included.