A Flexibly Grasping and Manipulating Mechanism Composed of Many Elastic Cords

(1st Report: Proposal of Mechanism and Analysis of Grasping Performance)

Abstract

A novel mechanism that can easily grasp and manipulate objects with a non-uniform shape or fragile structure is proposed. The mechanism is composed of many elastic cords connecting two circular rings. By giving relative rotation between the rings around the central axis, cords are squeezed, can wind about the object, and can grasp softly it. Euler’s belt theory is extended to establish analysis method of statics and kinematics between an elastic cord and an object modelled as a polyhedron. Then the motion of cords can be analyzed taking account of their slip, contact, and taking off. Experiments to measure cords’ behavior and gripping force with a prototype show the validity of the proposed theory. The prototype is mounted on a spatial serial robot arm, and then this manipulation system can softly pick various three-dimensional objects up and can move and place them with an adequate accuracy.