Robotic assist devices for bimanual physical therapy: preliminary experiments

Preliminary experiments were performed on a dynamically simplified system consisting of two outstretched hands constrained to flexion/extension while holding an object. A prototype device was designed to measure and assist in a transport task, in which the two hands moved a pencil-like object rhythmically back and forth, and in a bimanual squeezing task, in which the two hands squeezed the object. The device, operating under simple proportional feedback control laws, could substitute completely for one hand in both tasks. When the device assisted a hand partially disabled by ischemia, it produced torque that the disabled hand did not, allowing the tasks to be performed. These results demonstrate the capability of a device, operating under simple control laws, to assist a disabled hand, allowing performance of coordinated bimanual tasks. Such a robot, extended to more useful bimanual activities of daily living, could afford cost effective, objectively measurable, self-driven therapy for a large patient population