Experimental ankle exoskeleton system increases walking speed

Engineers at Stanford University have developed a prototype ankle exoskeleton system that was able to increase a person’s walking speed by at least 40% in an experimental setting. The ankle exoskeleton – which attaches around the shin and into an integrated walking shoe –could help many people overcome the frustrating problem of slower-than-desired-walking.

The ankle exoskeleton system tested in this research is an experimental emulator with a frame that fastens around the upper shin and into an integrated running shoe that the participant wears; it is attached to large motors that sit beside the walking surface and pull a tether that runs up the length of the back of the exoskeleton. Controlled by an algorithm, the tether tugs the wearer’s heel upward, helping them point their toe down as they push off the ground.

The engineers had 10 young, healthy adult participants walk with the exoskeleton system in different modes of operation: optimised for speed, optimised for energy use and a placebo mode adjusted to make them walk more slowly. In all of the tests, participants walked on a treadmill that adapts to their speed.

The mode that was optimised for speed resulted in an impressive 42% increase in walking pace, compared to when participants were wearing normal shoes and no exoskeleton.In addition to the increased walking speed, this mode also reduced energy use, by about 2% per meter traveled.

Meanwhile, the settings that were optimised specifically for energy use appeared to decrease overall energy use more than the speed-optimised settings, but did not increase speed as much. As intended, the placebo mode both slowed down participants and boosted their energy use

“My research mission is to understand the science of biomechanics and motor control behind human locomotion and apply that to enhance the physical performance of humans in daily life,” said Seungmoon Song, a postdoctoral fellow in mechanical engineering at Stanford University. “I think exoskeletons are very promising tools that could achieve that enhancement in physical quality of life.”

The engineers now plan to focus future versions of the ankle exoskeleton emulator on reducing energy use consistently across users, while also being more comfortable.

In considering older adults specifically, Steve Collins, associate professor of mechanical engineering, wonders whether future designs could reduce pain caused by weight on joints or improve balance: “A 40% increase in speed is more than the difference between younger adults and older adults. So, it’s possible that devices like this could not only restore but enhance self-selected walking speed for older individuals and that’s something that we’re excited to test next.”

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Tags: ankle exoskeleton system, Experimental

Category: Features, Technology & Devices