I. Introduction
The goal of developing a robotic hand is to improve grasping performance. What is commonly required for many hands is the ability to grasp an object stably. Although different definitions of stable grasping have been proposed, durability (which indicates how well the hand can keep grasping an object against a given disturbance while holding an object) is a critical index for evaluating stable grasping with a robotic hand. The anthropomimetic approach is often used to determine the grasping durability of a robotic hand. The anthropomimetic approach is based on the principle that human fingers contain elements that play a significant role in grasping an object. Therefore, many robot hands have been developed to mimic the human hand [1].