Grasping and in-hand manipulation: experiments with a reconfigurable gripper

This paper addresses the problem of grasping and manipulating three-dimensional objects with a reconfigurable gripper equipped with two parallel plates whose distance can be adjusted by a computer-controlled actuator. The bottom plate is a bare plane and the top one carries a rectangular grid of actuated pins that can translate in discrete increments under computer control. We propose to use this gripper to immobilize objects through frictionless contacts with three of the pins and the bottom plate, and to manipulate an object within a grasp by planning the sequence of pin configurations that will bring this object to a desired position and orientation. A detailed analysis of the problem geometry in configuration space was used in a previous paper to devise simple and efficient algorithms for grasp and manipulation planning. We have constructed a prototype of the gripper and this paper presents our experiments.