Utah engineers develop robotic exoskeleton for amputees

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Researchers from the University of Utah have developed a powered robotic exoskeleton to help amputees walk with less effort.  

Developed by mechanical engineers at the university’s Bionic Engineering Lab, the exoskeleton features embedded microprocessors and sensors running advanced control algorithms. “The exoskeleton’s AI understands how the person moves and assists how the person moves,” explained mechanical engineering graduate student Dante A. Archangeli, University of Utah.

The exoskeleton, which wraps around the wearer’s waist and leg, uses battery-powered electric motors to provide extra energy and make walking feel natural again. The device features a lightweight, efficient electromechanical actuator connected to the user’s thigh above the amputation.

The actuator can be swapped between the right and left side of the main harness to accommodate either leg, with the custom electronic systems, microcontrollers, and sensors contained in a harness.

University of Utah’s assistant professor in the department of mechanical engineering, Tommaso Lenzi, who led the project, likens the exoskeleton to an electric bike with a motor that gives the rider assistance in pedalling the bike uphill.

The team of researchers conducted a study in which six people with above-knee amputations tested the exoskeleton while their metabolic rate was recorded. The patients walked on a treadmill with and without the device on while their oxygen intake and carbon dioxide levels were measured.

All of those who tested the exoskeleton improved their metabolic rate – in other words, reduced their energy consumption – an average of 15.6% with it on, Lenzi said.

“It’s equivalent to taking off a 26-pound backpack. That is a really big improvement,” he added. “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.”

Another key factor is that this device is uniquely lightweight, according to Lenzi. The frame is made of a carbon-fibre material, while other parts are constructed of plastic composites and aluminium. The exoskeleton only weighs 5.4lb.

The group’s research was documented in a new paper published in the journal Nature Medicine. Lenzi believes the exoskeleton could become available in a couple of years. A US$985,000 (£722,500) grant from the U.S. Department of Defence funded the development of this new exoskeleton technology for the benefit of veterans.

Earlier this year, Lenzi received a new US$584,000 (£428,400) grant from the National Science Foundation. “The NSF grant will enable us to continue this work and build an even better device to help more people walk,” he added.

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