There are about 800,000 strokes per year in the United States. As a result of stroke, aging, injury and other conditions, more than 50 million Americans have restricted mobility.
Exoskeletons have certainly made an impact in this area in the last decade, aiding in rehabilitation and helping disabled or paralyzed people improve their gaits. But exoskeletons are heavy, due to their electronics and batteries, and they don’t come cheap – and just now are starting to be covered by some insurance providers.
Researchers at Carnegie Mellon and North Carolina State University, however, are looking to change this problem with their new exoskeleton boots that are lightweight and reduce the amount of energy it takes to walk by 7 percent.
In a new study (PDF) published in the journal Nature, the developers explain how the system mimics a human ankle and how it could significantly improve rehabilitation efforts.
An unpowered clutch engages a spring in parallel with the Achilles tendon when the foot is on the ground, offloading the calf muscles and making walking easier. Credit: Steve Collins
“The researchers’ exoskeleton structures, built of lightweight carbon-based materials, have a spring that connects the back of the foot to just below the back of the knee, where it attaches with a mechanical clutch. When the Achilles tendon is being stretched, the clutch is engaged and the spring, rather like an additional tendon, stretches and helps to store energy. After the standing leg pushes down, unleashing elastic energy, the clutch releases and absorbs the slack in the spring, in preparation for the next cycle.”
Current exoskeletons cost anywhere between $40,000 and $80,000, but the researchers of the exoskeleton boots hope they’ll cost no more than a few thousand dollars.
But there are still a few obstacles to overcome. For example, the 7% efficiency boost only applies at normal walking speed on level ground. So the researchers are now testing the exoskeleton boots in a broader range of conditions, and they’re looking into how to make them adaptable to an individual’s style of walking and sloping terrain.
