STABILITY INDEX AND CONTACT CONFIGURATION PLANNING FOR MULTIFINGERED GRASP

It is necessary to plan the contact configuration to guarantee a stabl e grasp. This article discusses the grasping stability of multifingere d robot hands. The fingers are assumed to be point contacts with frict ion. A stability index for evaluating a grasp, which is proportional t o the ellipsoidal volume in the grasping task space, is proposed. The invariance of the index is proved under an object linear coordinate tr ansformation and under a change of the torque origin. The similar inva riance of the index is also proved under a change of the dimensional u nit. The optimal grasping of an object by a multifingered robot hand c an be obtained using the stability index to plan the grasp configurati ons. The index is applicable to plan adaptable fixtures as well. A non linear programming method to plan configurations is addressed. Several examples are given using the index to evaluate a grasp, in which the obtained optimal grasping is consistent with what human beings expect. The sensibility of the optimal grasping is analyzed in these examples . (C) 1998 John Wiley & Sons, Inc.