Object Picking Through In-Hand Manipulation Using Passive End-Effectors With Zero Mobility

Abstract

This letter presents a new method for picking objects through quasistatic in-hand manipulation with end-effectors that have no degrees of freedom. Our stable manipulation/grasp planning is achieved with two contacts at fixed distance and the force of gravity, and is provably complete and correct. Practically, our robotic in-hand manipulation technique can facilitate low-cost manipulation and render simple end-effectors such as the parallel-jaw gripper more dexterous in picking, placing, and handing-off objects in case, for example, failing actuated grippers become frozen and it is impossible to exert sufficiently large internal forces. Our picking technique can also be applied to placing objects. Implementation and experimentation on a custom-made direct-drive manipulator and a conventional manipulator are presented. Many experiments were performed for both picking and placing and the results demonstrate usefulness of this method for manipulating a variety of common objects, with different geometries and surface conditions.