Design of an Underactuated Gripper for the Item Picking in Distribution Centers

Abstract

The particular category of the underactuated grippers is chosen for the automation of the item picking in distribution centers. The underactuated grippers have fewer degrees of actuation than degrees of freedom, so they are mechanically simpler than the fully-actuated grippers, and they are able to adapt to objects regardless of their shapes. However, the existing underactuated grippers found in the literature are regarded overdesigned because more than enough passive elements are included. This paper is aimed to design and build a more simplified but still workable underactuated gripper for the item picking. The designed gripper contains a cable-pulley driven underactuated finger which has two phalanges, and an opposite fixed finger. Moreover, the fingertip of the underactuated finger is intended to move along the ground where the target object is laid. The dimensions of the gripper are selected in order to achieve the following two tasks: picking the cylindrical objects from the ground and retaining the grasp during a lifting transportation. The experiment setup fails to drive the fingertip of the underactuated finger moving along the ground, but it is shown that the designed gripper is still able to fulfill these two tasks, except for the case that when the initial spacing between the moving underactuated finger and the object is rather large.