Artificial hand with stiffness adjuster

The paper deals with 5 finger hand based on the original finger mechanism consisting of a planetary gear system and serially connected 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 do not have any 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 configuration of gripping objects. The hand also has a mechanism for adjusting stiffness of fingers, which allows to give passive gripping force to a gripping object according to the object´s elasticity. Driving tests show that it achieves typical gripping and pinching motions of a human hand in daily life without any sensory feedback and also show that the stiffness adjuster works effectively.