Motor-Free Device Reduces Stress from Walking 2015-04-16

Devices that help people walk were once thought to be difficult, if not impossible, to design. Until recently, such a device required electricity from an external power supply. Now, American scientists have built a small, wearable addition to normal shoes. Their new invention eases the load on muscles in the leg and makes walking easier.

Steven Collins and Greg Sawicki are bio-medical engineers. They both studied how human beings walk. They found that our ankles and calves perform motions similar to a spring joined to a clutch. In an automobile, a clutch is used to connect and disconnect a driving or driven part of an engine or other piece of equipment. The researchers found that the human body parts are able to both store and release energy, just like a spring.

Steven Collins works with Carnegie Mellon University in Pennsylvania. Greg Sawicki is with North Carolina State University. He spoke to VOA on Skype.

"We found in basic science experiments that that system, your calf and Achilles tendon, works a lot like a catapult. So,the muscle holds on to the tendon and your body actually stretches your Achilles tendon quite a bit and then stores the energy in the tissue and then it's given back to propel you forward in the world."

Mr. Sawicki says he and Mr. Collins designed a mechanical device that performs the same kind of energy 'give-and-take' outside the body. Their new ankle exoskeleton is made of carbon fiber and metal. It connects to ordinary shoes and takes over part of the work of walking. Mr. Sawicki says the device reduces the amount of energy required for walking by as much as seven percent.

The unpowered ankle exoskeleton can help people walk farther with the same amount of energy. It also can restore normal movement for individuals who have trouble walking.

Mr. Sawicki says it takes only a few minutes for someone to get used to the ankle exoskeleton. He says the wearer quickly learns to use less muscle energy, letting the device do much of the work.

"You really don't notice it until when you take it off. And when you take it off you realize that it was there and giving you the boost."

Mr. Sawicki says the device is mainly meant for people recovering from a surgery operation or a stroke. He adds that anyone who spends a lot of time walking, like hospital workers and policemen, could use the device.

There are no plans to make the ankle exoskeleton available to the general public. But the inventors say some manufacturers have expressed interest in the device.

I'm Jonathan Evans.

VOA's George Putic prepared this story from Washington. Jonathan Evans wrote it for Learning English. The editor was George Grow.

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Words in this Story

boost n. help or encouragement; a push upward

exoskeleton n. an artificial external supporting structure

restore v. to give back someone or something that was lost or taken : to return someone or something

spring n. a twisted or coiled piece of metal that returns to its original shape when it is pressed down or stretched