A soft, wearable device designed for the lower leg has been shown to act as a kind of shock absorber for the human stride, literally putting a “spring” in each step.
The device, which works without any external power source such as batteries or a motor’ has been shown to improve the efficiency of walking by as much as seven percent in lab trials.
“The unpowered exoskeleton is like a catapult. It has a spring that mimics the action of your Achilles’ tendon, and works in parallel with your calf muscles to reduce the load placed upon them. The clutch is essential to engage the spring only while the foot is on the ground, allowing it to store and then release elastic energy. Later it automatically disengages to allow free motion while the foot is in the air,” said Dr. Gregory Sawicki, in a statement.
Sawicki is a biomedical engineer and locomotion physiologist in the joint NC State/University of North Carolina-Chapel Hill Department of Biomedical Engineering and co-author of a paper on the device published in the journal Nature.
The researchers believe that the device could potentially help everyone, but will be especially useful for people who do a great deal of walking or who have medical issues which make walking difficult. Frequent hikers, runners, soldiers, people with leg injuries or the elderly.
The researchers tested the “exoskeletons” on nine able-bodied adults. Each test subject walked on a treadmill without the devices for a baseline comparison and then again with a device on each leg. The results showed a seven percent improvement in the efficiency and energy consumption of the walkers.
“A 7 percent reduction in energy cost is like taking off a 10-pound backpack, which is significant. Though it’s surprising that we were able to achieve this advantage over a system strongly shaped by evolution, this study shows that there’s still a lot to learn about human biomechanics and a seemingly simple behaviour like walking,” Sawicki said.
The exoskeleton device uses a simple mechanical clutch to hold a spring as it expands and contracts with each step. The researchers expect that it will cost just a few hundred dollars and that people can be trailed to use it in a matter of hours.
“When you first fit it on, it feels a bit odd and strange but when you start to walk around with it on it soon feels comfortable and normal. But the real effect is when you take it off again – your foot feels heavy and weak afterwards,” Steven Collins, a mechanical engineer at the Carnegie Mellon University in Pittsburgh, Pennsylvania told the Independent.
The lower leg device could just be the first step in making basic movements easier and more efficient for the injured, aging and able bodied alike.
“Someday soon we may have simple, lightweight and relatively inexpensive exoskeletons to help us get around, especially if we’ve been slowed down by injury or aging,” said Collins.
