Figure 13

Prosthetic hand control. (a) Photo sequence of an able-bodied test subject performing the unscrewing task with the Motion Control Hand (top), and i-Limb Ultra (bottom). The prostheses must be manually rotated using elbow and shoulder motions to produce rotation of the object once in grasp. The angular position of the object is denoted as β. In essence, prosthetic hands function similar to a crescent wrench during this task. (b) The Motion Control hand under sliding mode control. A contraction of the EDC (E _E ) causes the hand to open, while a contraction of the FCR (E _F ) causes the hand to close. The prosthesis must be manually rotated as in (a) to rotate the grasped object.