University of Utah engineers create powered exoskeleton for amputees

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(Courtesy of the University of Utah)

SALT LAKE CITY (ABC4) – Mechanical engineers at the University of Utah have developed a powered exoskeleton to help amputees walk again.

The U of U’s Bionic Engineering Lab says the powered exoskeleton uses motors, microprocessors, and advanced algorithms to help users walk with less effort, similar to how an e-bike helps riders pedal uphill.

The device is lightweight — weighing only 5.4 pounds — which is key for comfort and usability. The frame is composed of a carbon-fiber material while other parts are made of plastic composites and aluminum.

The exoskeleton wraps around the person’s waist and leg. It’s powered by battery-operated electric motors and microprocessors. There’s an electromechanical actuator connected to the user’s thigh above the amputation and a waist harness containing custom electronic systems, microcontrollers, and sensors running advanced control algorithms.

“Above-knee amputation severely reduces the mobility and quality of life of millions of individuals, in large part because much of the leg’s muscles are removed during surgery,” researchers say.

“The consequence of this, even though you have the ability to move your hip, is your abilities in walking are quite impaired,” says Tommaso Lenzi, the mechanical engineering assistant professor leading the project. “There is a lack of strength and range of motion.”

Since a standard prosthetic leg cannot fully replicate the natural movement of a human leg, above-knee amputees work harder while walking, overexerting limb energy while carrying the prosthetic. For leg amputees who tested the exoskeleton, their energy consumption was reduced by an average of 15.6%.

“It’s equivalent to taking off a 26-pound backpack,” says Lenzi. “That is a really big improvement. We’re very close to what an average person would expend at the same speed. The metabolic consumption is almost indistinguishable from that of an able-bodied person, depending on the fitness level.”

For 74-year-old leg amputee Stan Schaar, he never believed he would feel the effortless sensation of walking again. When he tried the exoskeleton, everything changed.

“The first time I used it, it was like my muscles were totally fused with this exoskeleton, and it was helping them move faster,” says Schaar. “It helped my leg to relax and just move forward and walk. I could probably walk for miles with this thing on because it was helping my muscles move.”

Lenzi is hoping to clear the exoskeleton for the mass market soon. He believes the device could become available in just a few years. A $985,000 grant from the U.S. Department of Defense funded the ambitious project and earlier this year, a $584,000 grant from the National Science Foundation will bolster the project even more.

“The NSF grant will enable us to continue this work and build an even better device to help more people walk,” says Lenzi.

“I’m a person who doesn’t have a lot of muscle left in my residual limb,” says Schaar. “This device makes up for a lot of what they had to take away. There’s nothing that will ever replace a flesh-and-bone leg, but this comes pretty close. I hope they get this thing on the market soon.”

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