Evaluation of grasps for 3D objects with physical interpretations using object wrench space

Abstract

In this paper, we present a practically useful and intuitive grasp quality measure that takes into account the shapes of object geometries and the torque limits of finger actuators. The proposed grasp quality measure is defined by the distance between the convex hulls of the absolute grasp wrench space (a-GWS) and the object wrench space (OWS), where a-GWS and OWS are, respectively, created by the active wrenches from the robot fingers with limited torque bounds and the uniform distribution of unitary normal disturbances on the surface of a polyhedral object. The computational algorithm for the grasp quality measure also yields the information of which spots of the object are fatal under the disturbance, which makes the algorithm practically useful. We demonstrate the validity of the proposed measure through numerical examples.