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Smart Robotic Leg Prosthesis Being Developed

Kerry Finn and Tommaso Lenzi

Kerry Finn, left, talks with engineering professor Tommaso Lenzi (Mark Helzen Draper, University of Utah)

31 Oct. 2019. A project is underway to develop a smarter and lighter-weight motorized leg prosthetic device that gives the wearer better balance and control. The Utah Bionic Leg project, led by University of Utah mechanical engineering professor Tommaso Lenzi, received grants in the past two months totaling $2.8 million, from National Institutes of Health and National Science Foundation.

Lenzi and colleagues in the university’s Bionic Engineering Lab in Salt Lake City is seeking better prosthetic devices for people with above-the-knee amputations. Lenzi cites data showing some 400,000 people in the U.S. are living with these amputations, as a result of trauma or complications from diabetes, and face limited mobility as well as further health problems, such as back pain, osteoarthritis, and depression.

Current prosthetics, however, are designed for younger and stronger individuals, who despite having lost a leg, can still function with a passive prosthetic device. The Utah team is designing a prosthetic device for older and less mobile individuals by offering a lighter device with a support system to assess the wearer’s environment. That support system can then provide more customized assistance to the wearer.

An early-stage robotic leg prosthesis from Lenzi’s lab has sensors and battery-powered motors, controlled with a processor powered by algorithms that aim to give the wearer the ability to walk with less stress on the body than passive prosthetic devices. “If you walk faster, it will walk faster for you and give you more energy,” says Lenzi in a university statement. “Or it adapts automatically to the height of the step. Or it can help you cross over obstacles.”

In addition, the device uses lighter-weight materials, such as aluminum and titanium, [sponsored links] and thus weighs about six pounds, half the weight of other advanced-technology prosthetic devices in development. In addition, the Utah device uses smaller batteries. But Lenzi says the design of the technology also keeps the device lighter in weight, since “all of the elements play together.”

The new funding includes $2.2 million over five years from the Eunice Kennedy Shriver National Institute of Child Health and Human Development in NIH. That grant supports research to identify key prosthetic technologies for people with above-the-knee amputations. The study is expected to refine the systems and control network for walking at varying speeds and better synchronize the prosthetic device with the wearer’s remaining leg for more demanding tasks, such as stair climbing. And while the current device has been pilot-tested with younger individuals, the team wants to extend those tests to older persons.

The National Science Foundation grant supports work with ultrasound and mechanical sensors to better understand the wearer’s environment, and help anticipate obstacles to navigate the terrain. The four-year, $600,000 award funds the lab’s work on design guidelines for the prosthetic device to best use the sensors, determine algorithms to process data for anticipating obstacles, and develop control routines that combine data from ultrasound and mechanical sensors.

Kerry Finn, a 60 year-old man who lost his leg due to diabetes complications, is taking part in early tests of the device. “It made me feel like I could do things I could not do before,” says Finn. “Every time I made a step, it was an awesome feeling.”

This video from University of Utah demonstrates the current prosthetic device.

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