Internal force computation of grasped object using joint torques

Grasping and manipulation are the most important key functions for service robots to help people to handle the everyday tasks in household. After the object is grasped, the internal force between the hand and object is very important for fine manipulation. In this paper, we present the computation of internal force of grasped objects using joint torques. An automatic grasp planning system is used to generate grasps with high grasp quality for Schunk Anthropomorphic Hand with 13 degrees of freedom. Optimal grasp forces are computed as a linear matrix inequalities problem, and are exerted using embedded joint torque based finger impedance control. Computation of force at the fingertip, the internal force for grasps with multiple contact points and the external forces exerted onto the object after grasping are introduced. In case of multiple contact points, it is assumed that the external force is distributed equally among all contact points on one finger. Experimental results show the feasibility of our methods.