Contents I. Introduction
Recently, many kinds of robotic hands aiming at the application to an artificial arm or a humanoid robot have been developed [1]–[9]. In [2], the multi-fingered haptic interface was developed and the haptic interaction which enables users to interact and feel the virtual object safely was implemented and tested. [3] presented a newly developed kinetic humanoid hand with high potential for dexterous manipulation, which has a distributed tactile sensor with 895 detecting points. [4] introduced a newly developed high-speed and high-power grasping robotic hand with 8-joints and 3-fingers. The hand can close its joints at 180deg per 0.1s, and the fingertips have an output force of 28N, and experimental results of the highspeed hand catching a falling object are shown. In [5], mechanisms of the developed humanoid robotic hand in which shape, size, mass and functions all are close to humans were presented, and the history of the development to achieve a pinching function was also explained. [6] proposed the four fingered robotic hand with dual turning mechanism where two and two other fingers can independently rotate inner and outer circles with the common center, respectively. [7] presented a first design and analysis effort of an artificial extensor mechanism, and a newly robotic hand prototype which takes extensor mechanism into consideration was proposed. In [8], an anatomically-correct testbed (ACT) of the human hand was investigated to understand human hand's mechanisms, function, and control. Based on the importance of the extensor mechanism to realize the human-like finger movements, design of the bones and joints that form the skeletal structure for the ACT Hand was presented. [9] proposed a design of underactuation for wire-driven anthropomorphic hands.
