Carnegie Mellon University’s Steve Collins and his collaborator Greg Sawicki at North Carolina State University have discovered a way to make humans more efficient at walking.
In a new report in the journal Nature, they describe a lightweight, unpowered, wearable exoskeleton they developed to reduce the energy cost of human walking. This wearable boot-like apparatus, when attached to the foot and ankle, reduces the energy expended in walking by around 7% — approximately equivalent to removing a 10-pound backpack.
The walking assist clutch is simple, so it would be inexpensive to produce. It is lightweight and requires no power source.
“Think of nurses, emergency response workers, soldiers, or the millions of other people who walk many hours a day—7% would make a difference to them,” Collins said.
Another population that might benefit from this technology includes those with disabilities or recovering from injuries.
Although Collins cautions against being too speculative, he is optimistic. “Someday soon we may have simple, lightweight and relatively inexpensive exoskeletons to help us get around, especially if we’ve been slowed down by injury or aging.”
Collins runs the Experimental Biomechatronics Lab. He is an assistant professor in the Department of Mechanical Engineering with a courtesy appointment in the Robotics Institute.
The walking assist clutch uses a spring that acts like the Achilles’ tendon and a clutch that mimics the calf muscles. The difference is that the spring and clutch do not expend any energy the way tendons and muscles do.
“The unpowered exoskeleton works in parallel with your muscles, thereby decreasing muscle force and the metabolic energy needed for contractions,” says Greg Sawicki, a biomedical engineer at North Carolina State University and co-author of the article.
The device reduces the load placed on the calf muscles and the spring stores and releases elastic energy. The clutch engages the spring while the foot is on the ground, disengaging it while the foot is in the air.
While muscles waste energy in producing force, this simple device does so passively.
“We asked ourselves years ago, ‘Is there a way to assist a human in the task of walking by reducing their own energy use without needing an additional energy source?’” Collins said. “The answer to this question, it turns out, is ‘yes.’”