Artificial Finger Consisting of Closed Linkages and Single Planetary Gear System: an Approach to Grasp Stabilizing with Distal Hyperextension Joint

EasyChair Preprint 13519

Abstract

The authors have developed a five-finger robot hand. Four fingers  (index, mid, medicinal, and little) have two serially connected closed four-bar linkages and Single Planetary Gear System (SPGS). It is a two-degree-of-freedom (2-DOF) mechanical system that drives actively and passively. It constitutes a variable stiffness mechanism (VSM) that achieves sensorless shape-fitting motion (envelope grasping) when grasping an object of unknown shape. This mechanism gains robustness on harsh environmental usages since no electric or electronic devices are embedded in the finger part. However, the mechanism of such an under-actuation system requires stability in its motion, specifically, stable object grasping or pinching. It must be achieved on a mechanical basis, not by control maneuver.

Recently, we developed a new finger mechanism having a Hyperextension joint at the fingertip aiming for passively stabilizing the pinching motion. This study shows the mathematical formulation of the finger mechanism to compute its static motion and force that the fingertip applies to an external object. In addition, it shows that VSM allows control of the force applied by the fingertip to an external object.

Keyphrases: hyperextention joint, planetary gear system, under actuated finger mechanism

@booklet{EasyChair:13519,
  author    = {Yuma Eto and Koichi Koganezawa and Yoshihiro Kai},
  title     = {Artificial Finger Consisting of Closed Linkages and Single Planetary Gear System: an Approach to Grasp Stabilizing with Distal Hyperextension Joint},
  howpublished = {EasyChair Preprint 13519},
  year      = {EasyChair, 2024}}