A letter published online April 1 by Nature reported that an unpowered exoskeleton reduces the metabolic cost of walking by 7.2 ± 2.6% for healthy human users under natural conditions, savings comparable to those with powered devices.
The device’s inventors, scientists at the Department of Mechanical Engineering at Carnegie Mellon University in Pittsburgh and the Joint Department of Biomedical Engineering, North Carolina State University in Raleigh and the University of North Carolina at Chapel Hill, call their creation the “ankle exo.”
The lightweight elastic device acts in parallel with the user’s calf muscles, offloading muscle force to reduce metabolic energy consumed in contractions. It uses a passive mechanical clutch to hold a spring as it is stretched and relaxed by ankle movements when the foot is on the ground.
