Development of a light duty arm with an active-fingertip gripper for handling discoid objects

This paper describes a development of a light duty arm with an active-fingertip gripper for handling discoid objects. The system is potentially capable of sharing the workspace with human workers, assuming the use in a cell manufacturing system. We propose a new 3-DOF gripper mechanism with two fingers which symmetrically move in parallel and each finger has a 2-DOF fingertip of a cylindrical shape. We also develop a lightweight arm with a weight compensation mechanism which is composed of a non-circular pulley and a spring to minimize required actuator torque. After verification of basic performance, the hand-arm system successfully performs a pick-and-place task for a discoid object from horizontal placement to vertical placement and vice versa. We demonstrate continuous 100 times pick-and-place operations without failure where its cycle time almost equals to a human worker.