Emulating the Motion of a Human Upper Limb: Controlling a Finger-arm Robot by using the Manipulability of its Finger

In this paper, a 3-DOF robot finger is fixed onto the end-effector of a 6-DOF robot arm to realize a finger-arm robot. As in the case of the upper limb of a human being, the finger- arm robot possesses a high degree of freedom. This paper describes a new method to control the finger-arm robot so as to simply generate a natural motion emulating the movement of a human upper limb. To achieve this, a control method based on the manipulability of the finger is proposed. By using the proposed method, the finger primarily moves to complete a delicate local task, while the arm only moves to assist the finger when the manipulability of the finger falls below a reference value. The proposed method was applied to the task of drawing two 3D figures. The obtained results clarify the relation between manipulability and kinetic energy and also demonstrate the effectiveness of the proposed method.