Commercial Robotic Leg Could Benefit Both Higher- And Lower-mobility Amputees

A commercialized robotic limb could perchance use some higher- and lower-mobility amputees, University of Michigan roboticists person shown for nan first time. 

The limb provided nan largest gains erstwhile nan U-M squad applied its ain power strategy, enabling a much symmetrical gait, little tripping risks and a simplification successful strain connected nan study participants' sound legs and hips.

The Michigan squad worked pinch Össur's Power Knee, provided by nan company, pinch superior backing from nan National Institutes of Health. 

Multiple robotic prosthetic legs are connected nan marketplace but aren't yet successful wide objective use. For galore activities, nan lightness and simplicity of passive legs is preferred by prosthesis users. However, for peculiarly taxing activities for illustration rising from a chair, climbing stairs and hills, and stepping agelong distances, nan summation of powerfulness has nan imaginable to thief prosthesis users beryllium much progressive while besides preventing overuse injuries.  

"The passive limb has a immense advantage successful this study because nan participants usage it each time and are very utilized to its behaviors. Our study participants had conscionable 2 training sessions pinch nan powered leg. Even pinch that disadvantage, we observed benefits of nan powered limb pinch some our controller and Össur's," said Robert Gregg, a professor of robotics and corresponding writer of nan study successful nan Journal of NeuroEngineering and Rehabilitation.

"Our study is important because grounds was antecedently lacking for benefits of robotic knees complete precocious passive knees, which is simply a large logic security companies don't typically screen robotic knees. Our results statesman to supply this evidence."

In this first study, nan researchers focused connected cardinal activities of regular surviving successful which a powered prosthesis could supply meaningful benefits compared to passive knee prostheses. Study participants many times sat and stood; walked quickly connected a treadmill; and many times sat successful a chair, walked and sat down again. 

Prosthesis users who required other stepping assistance, specified arsenic a cane, recovered that nan Power Knee offered important thief successful each these tasks. Those who get astir much easy connected their ain prostheses saw nan astir betterment successful their gaits erstwhile Gregg's squad implemented their ain power algorithm connected Össur's leg. One caller amputee described it arsenic nan closest they'd felt to two-legged stepping connected a prosthesis.

Our extremity successful prosthesis power is to make nan limb behave arsenic adjacent arsenic imaginable to nan missing quality limb successful bid to forestall compensations that often lead to overuse injuries. It besides matters because gait deviations tin bring unwanted attraction to immoderate users."

Kevin Best, investigation subordinate successful robotics, caller U-M robotics PhD postgraduate and first writer of nan study

The squad investigated 2 fundamentally different power approaches. Össur's much accepted controller relies connected recognizing circumstantial features of nan user's motion, indicating what they're astir to do. This makes nan strategy secure and predictable but whitethorn not ever support up pinch nan user's intent, Gregg said. In bid to sit, users person to hold for nan knee to admit nan sitting mobility earlier it will bend, and likewise pinch standing. 

In contrast, nan power attack developed by Gregg's squad continually adjusts to nan user's motion. They built mathematical models of really humans move, based connected ample datasets of unimpaired individuals. At each infinitesimal successful time, their power algorithm measures nan user's thigh mobility to find nan correct behavior, creating much earthy knee motions that are amended synchronized pinch nan user.  

"With nan improvements successful robotic devices, it is clear that robotic prostheses connection awesome committedness to nan amputee population," said Jeff Wensman, a certified prosthetist/orthotist astatine Michigan Medicine and study co-author. "I americium excited to spot nan advancement of a strategy to supply powered prosthesis users pinch user-synchronized control. I judge that this is simply a missing nexus to making powered prosthetics a reality for amputees."

This caller power algorithm is harder to study aft utilizing a accepted prosthesis for years, but nan repeated sit-to-stand tests showed that participants were learning. Rather than getting much tired pinch each trial, they sewage faster. Then while walking, nan much mobile group showed 2 improvements that could go important benefits. 

First, they lifted nan toed of nan prosthetic ft higher, reducing nan consequence of tripping complete mini obstacles aliases rougher terrain. Second, they didn't request to plaything their hips arsenic difficult to move nan prosthetic limb forward, hinting that nan powered knee and lifelike power algorithm could perchance trim backmost symptom and let users to spell farther earlier getting tired, though nan squad couldn't measurement this pinch nan short study.  

Next, nan squad hopes to show nan information and effectiveness of their power algorithm pinch stairs and ramps, followed by take-home tests. With much clip to practice, nan participants whitethorn beryllium capable to execute moreover more. If nan power strategy is successful, Össur could incorporated aspects of it into its ain algorithm.

For now, nan improvements pinch Össur's ain algorithm were capable for 2 of nan study participants to move to nan Power Knee for their mundane prosthesis, demonstrating that robotic prostheses are moving from laboratory exploration to real-world benefit.

Primary backing by nan National Institutes of Health was nether grant No. R01HD094772, pinch further support from nan National Science Foundation. Össur provided first financial support and whitethorn person a financial liking successful nan results.

The squad has applied for patent protection for their controller pinch nan assistance of U-M Innovation Partnerships.