Progressive neuromuscular diseases such as muscular dystrophy and amyotrophic lateral sclerosis (ALS) often rob patients of muscular control early on and get progressively worse, while spinal cord injury can halt mobility immediately. The loss of functional independence adds to the stress and discomfort inherent with the diseases and injuries. Several universities and companies in the U.S. such as ReWalk Robotics and Ekso Bionics have designed lower limb devices that give back the ability to walk to properly trained patients. These devices are controlled by signaling buttons, leaning forward, or weight shifts as patients learn to use them.
Japan’s Cyberdyne employs bioelectric data to control each joint of HAL (Hybrid Assistive Limb) for Medical Use Lower Body. Approved for sale in Japan and Europe but not at this time in the U.S., HAL is the product of the University of Tsukuba’s Dr. Yoshiyuki Sankai, now CEO of Cyberdyne. It is a motor-controlled exoskeletal device controlled by a hybrid of three types of cybernic signals: voluntary; autonomous; and impedance. Cybernic Voluntary Control is based on bioelectric signals from sensors placed on the thigh, other body parts, and the brain that indicate the intention to move. Cybernic Autonomous Control draws from a database from healthy walkers, and Cybernic Impedance Control signals compensate for the pieces, friction, and mass of the HAL device. The combination of control signals can be adjusted to activate the motors for each joint to allow for individual and situational specifics. In Japan, HAL for Medical Use is approved for patients with progressive diseases. In Europe, HAL is used more commonly with job-related spinal cord injuries. The goals are to delay progress of a disease or, in the case of injury, to regain control and independence.
Photos and videos of the Cyberdyne device bring to mind Empire Storm Troopers, but the independence of function it promises is a real life wonder. The growing proliferation of exoskeleton designs and devices is not only helping patients right now but promises even more development and progress in the future.