In this section, let us consider the design method to achieve high dexterous motion of the robot hands. So far, the underactuation is a well-known approach to obtain higher degree of freedom than the number of the actuators used, but it can not guarantee the precision grasp and leads to limited finger postures. As a result, many other research groups developed their robot hands with one or two links per each finger for firm grasps by abandoning the dexterity of the robot hands. As expected, these approaches can not provide natural motion of human hands. To overcome the shortcomings of the underactuation, the electromagnetic(EM) joint locking mechanism for the dexterous motions of the robot hands was proposed by Shin et al. (2013).