Misalignment Force Control in Two Manipulator Systems

Abstract

An algorithm is developed for controlling the internal forces generated in an object when two arms with end-effector misalignments interact by grasping that object. The object may be rigid or have multiple degrees-of-freedom. Each manipulator is outfitted with a force torque sensor attached to its end-effector. Those forces/torques which are due to misalignments between the two arms are partitioned out of the measured forces/torques. A force controller is then designed to control these forces. Joint correction angles are calculated by use of the manipulator inertia matrices and the position controller gains. Each time the misalignment forces exceed a given threshold value the controller generates correction angles. These corrections are maintained until another violation of the threshold occurs.