A Prototype of Index-Finger PIP Joint Motion Amplifier for Assisting Patients with Impaired Hand Mobility

The authors proposed a methodology of assisting the patients who were suffering from mobility impairment of finger and thumb joints, with exoskeletal devices. The types of exoskeletal assistive devices for such patients were categorized into several groups based on required functions which are derived from the patients\´ condition. One of the categories, "joint motion compensator" is a novel concept taking into consideration the difference between active-ROM (range of motion) and passive-ROM of joints, and with regard to one of subgroups of this category called "joint motion amplifier", a prototype device which amplifies the motion of index-finger PIP (proximal interphalangeal) joint was constructed and verification experiments for pinching objects were conducted. The results revealed that it was feasible to pick up and pinch objects which were not so small or thin enough to be picked without nails, and also was possible for the device to hold such objects as strongly as human hands do.