Artificial hand with stiffness adjuster

Abstract

The paper deals with a five-finger hand, which is based on the original finger mechanism consisting of a planetary gear system and the compound four bar linkages. It takes an all-in-one design: all of the actuators (total five DC motors) are embedded into a palm, while finger parts have no electronic devices for attaining to be inherently safe as an end-effector. The mechanism allows us adaptive synergic motions of three joints of a finger (MP, PIP, and DIP) according to the shape of the objects to be gripped. The hand has a novel mechanism for adjusting stiffness of fingers, which provides an ability to give passive gripping force to a gripping object according to its elasticity. Driving tests show that it achieves fundamental motions of a human hand in daily life without any sensory feedback and also shows that the stiffness adjuster works effectively.