On the design of 2-DOF robot grippers

The gripper constitutes the end of the kinematic chain of an industrial robot and makes possible the interactions with the work environment. Although universal grippers with wide clamping ranges call be used for varied object shapes, in many cases they must be adapted to specific work-pieces shapes. The mechanical two-finger grippers with a single degree of freedom are the most usual device used in industry today. The fingers have symmetrical motions with respect to the gripper axis. In some applications, the position of the work piece with respect to the gripper frame may not be very precisely. It Is the case Of the unmatched or semi-finished parts in the interoperations transfer. A particular category of grippers for industrial robots has two degrees of freedom and a single driving motor. The relative positions of the component elements depend oil the frictional coefficients between work piece and fingers and on the initial position of the work piece with respect to the gripper's frame. The paper presents some considerations oil the design of the 2-DOF robot grippers.