Unified control of contact and joint space drift in multifingered robot hands

A general approach for controlling the system configuration drift resulting from the presence of nonholonomic constraints and kinematic redundancy in multifingered robot hands is presented. A redundant multifingered robot hand for grasping and manipulating an object using 3-D rolling contacts is considered. The configuration space of a multifingered robot system (i.e., the hand and a grasped object in contact) is described in terms of finger joint variables and contact variables. In the context of motion repeatability, the combined effect of the redundancy in the system generalized variables and the non-integrability of the hand kinematics equations generate undesirable drift of both finger joint variables and finger/object contact locations. A stable method of drive compensation is proposed for controlling a general case of redundant 3-D rolling robot hands that manipulate an object along a given trajectory