A New Four-Fingered Robot Hand with Dual Turning Mechanism

This paper newly proposes the four-fingered robot hand with dual turning mechanism where two and two other fingers can independently rotate inner and outer circles with the common center, respectively. Due to this mechanical configuration, it has the particular rotating axis where the manipulation around the axis can be completely decomposed into the velocity control around the axis and the internal force control in the contact plane. We achieved a manipulation task around the axis with the time of 0.8[sec] for one rotation, while it is relatively slow for another axis.

I. Introduction

While a multi-fingered robot hand as shown in Fig. 1(a) has a potential capability for achieving a dexterous manipulation, most of the conventional robot hands move either very slowly or awkwardly, especially in manipulating an object by finger tip. In manipulating an object by a multi-fingered robot hand, we have to be careful for both motion planning of finger tip and contact force management with considering the rolling motion, sliding motion, and even internal force balance in each sampling interval [1]–[8]. Also, in order to achieve a beautiful manipulation, we are obliged to make cooperating control for many actuators, such as nine for three fingers and twelve for four fingers, with accommodating actuator gain as equal as possible among joints at any phase. The adaptive gain tuning, however, is not so easy, because each actuator receives a different load depending upon its finger posture. We believe that these are reasons why it is hard for a multi-fingered robot hand to achieve beautiful motions.