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The exoskeleton that could stamp out slow walking frustrations

HT World reports on an innovative tech solution to an age-old problem.

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Being unable to walk as quickly as you’d like is a widespread frustration that commonly comes with age. But health tech pioneers may well have a solution.  

Engineers at Stanford University have tested a prototype exoskeleton system which attaches around the shin and into a running shoe.

It is externally powered by motors and controlled by an algorithm. When the researchers optimised it for speed, participants walked, on average, 42 per cent faster than when they were wearing normal shoes and no exoskeleton.

Steve Collins, associate professor of mechanical engineering at Stanford, says: “We were hoping that we could increase walking speed with exoskeleton assistance, but we were really surprised to find such a large improvement. Forty per cent is huge.”

In this initial set of experiments, participants were young, healthy adults; but researchers plan to run future tests with older adults and to look at other ways the exoskeleton design can be improved.

They also hope to eventually create an exoskeleton that can work outside the lab, though that goal is still a ways off.

Seungmoon Song, a postdoctoral fellow in mechanical engineering and lead author of the paper, says: “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.

“I think exoskeletons are very promising tools that could achieve that enhancement in physical quality of life.”

The ankle exoskeleton system tested in this research is an experimental emulator that serves as a testbed for trying out different designs.

It has 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.

For this study, the researchers had 10 participants walk with five different modes of operation.

They walked in normal shoes without the exoskeleton, with the exoskeleton turned off and with the exoskeleton turned on with three different modes: 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 – which resulted in the 42 per cent increase in walking pace – was created through a human-in-the-loop process. 

An algorithm repeatedly adjusted the exoskeleton settings while the user walked, with the goal of improving the user’s speed with each adjustment. 

Finding the speed-optimised mode of operation took about 150 rounds of adjustment and two hours per person.

In addition to greatly increasing walking speed, the speed-optimised mode also reduced energy use, by about 2 percent per meter traveled.

However, that result varied widely from person to person, which is somewhat expected, given that it was not an intentional feature of that exoskeleton mode.

“The study was designed to specifically answer the scientific question about increasing walking speed,” Song says.

“We didn’t care too much about the other performance measures, like comfort or energy. However, seven out of 10 participants not only walked faster but consumed less energy, which really shows how much potential exoskeletons have for helping people in an efficient way.”

Now researchers have attained such significant speed assistance, they plan to focus future versions on reducing energy use consistently across users, while also being more comfortable.

In considering older adults specifically, Collins and his lab wonder whether future designs could reduce pain caused by weight on joints or improve balance.

They plan to conduct similar walking tests with older adults and hope those provide encouraging results as well.

“A 40 per cent 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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