Thin and active fixture to hold finger for easy attachment and comfort of grasping support exoskeleton

This paper proposes a new thin fixture that improves comfortableness and makes it easy for a user to wear a grasping support exoskeleton. Easiness of wear is one of important factors for the system performance improvement in addition to physical support functions of the system. The fixture consists of a C-shaped SMA wire and an air chamber. The SMA wire generates a holding force to fix the exoskeleton to a user´s finger. The air chamber deforms the SMA wire to open its ends for attachment and detachment. This fixture reduces wearer´s burden due to a lightweight, about 1[g], and no hindrance of a finger motion due to thin profile, 2[mm]. The fixture is evaluated through some experiments from the viewpoint of holding force, contact pressure, finger skin temperature, attaching time and detaching time. This fixture can maintain blood flow by changing the holding force that depends on pressure of compressed air. Time spent for donning and doffing a grasping force support system becomes 80 or more percent shorter than one of Velcro.