Dynamical model and prototype tests of a self-adaptive mechanical hand

This paper concerns studies on a gripping member consisting essentially of a underactuated mechanism, for which has recently been granted an industrial patent. This gripping member can be used both as a gripping robotic end effector for industrial applications and, mainly, as prosthesis of human hand. Thanks to under-actuated mechanism and the adaptive drive scheme, the whole system uses only one motor and inextensible tendons. This mechanism makes it possible to each finger to adapt its configuration for almost all the possible object surfaces. So each of the fingers can grab the object almost always with the same force; this regardless of the configuration of the finger itself and regardless of the configuration of the other fingers. The grasping force is controlled just by controlling the force exerted by the only actuator. Preliminary kinematic and dynamic studies are summarized. Finally the first trials of a prototype are shown.