Five-fingered assistive hand with mechanical compliance of human finger

This paper introduces an exoskeleton assistive hand that supports human hand and wrist activities by using user\´s bioelectric potential to control the exoskeleton movement. The exoskeleton has three active joints for an index finger, three active joints for combination of a middle finger, a ring finger and a little finger and two active joints for a thumb. It also has two passive joints between the index finger part and the combined part of the three fingers. Our proposed poly-articular tendon drive mechanism simulates a mechanical compliance of a human finger so that the exoskeleton could realize comfortable and stable grasping. This paper proposes a new mechanism "dual sensing system" and a new control algorithm "bioelectric potential-based switching control" so that the exoskeleton could synchronize wearer\´s hand activities without any force sensor. A tendon-driven mechanism and a dual sensing system enable wearer\´s fingers to move freely when they does need power assist but precise position control or force control. A bioelectric potential-based switching control enables the exoskeleton to augment their grasping force only when wearer\´s fingers generate a relatively large grasping force. A five-parallel-link mechanism is used to assist wrist activities of a wearer. Through experiments it is confirmed that the exoskeleton does not disturb a wear\´s pinch of a small object and that it augments grasping force for a heavy work.