**3.2 Advantages in finger behavior**

Torque Limiter Mechanism has some advantages on the operation of the Universal Robot Hand II. The behavior of the finger with the mechanism is shown in Fig. 9 and Fig. 10. The PIP joint and the DIP joint are normally located as shown in Fig. 9 (a). The DIP joint is flexed in conjunction with PIP joint as same degrees. It is thought that excess overload is operated at the distal phalanx. As shown in Fig. 9 (b). If torque by the external force exceeds setup skidding torque, modules of drive gearing are turned over toward the direction of fending off the force to the mechanical stopper as one structure. This mechanism doesn't only make the actuators to be protected against the overload, but also support the external force mechanistically without output power of actuators by the position of particularity.

Fig. 9. Overloaded operation with torque limiter mechanism

Flexible grasp with Torque Limiter Mechanism is as shown by Fig. 10. Typically, a robot finger takes the form in Fig. 10 (a) in case of grasping a thin object. This is because that the commonly-used robot hand has engaged DIP and PIP joints in imitation of human joints. On the other hand, in case of grasping a thin object with human fingers, these fingertips are collimated, and increases area of contact between these finger pads. Thus, developed robot hand operates skidding mechanism in the DIP joint. Robot fingertips are collimated, and increases area of contact in Fig. 10 (b). Herewith, developed robot hand doesn't pinch a thin object with a point contact but with plane contact.

Fig. 10. Clip operation with thin object
