A team of scientists from Harvard have created a "robotic" exosuit that means the wearer uses less energy while walking. Published in Science Robotics, it is able to produce the highest reduction in energy expenditure for an exosuit tethered with a cable.
The newly developed exosuit significantly cuts the amount of energy the wearer expends while walking. This could have applications in many different fields, from aiding soldiers carrying heavy packs over long distances to helping people who have suffered strokes or other health complications to walk again.
“In a test group of seven healthy wearers, we clearly saw that the more assistance provided to the ankle joints, the more energy the wearers could save with a maximum reduction of almost 23 percent compared to walking with the exosuit powered-off,” explains Conor Walsh, who led the team in developing the new kit. “To our knowledge, this is the highest relative reduction in energy expenditure observed to date with a tethered exoskeleton or exosuit.”
The suit is made of flexible, stretchy fabric that wrap around the calves of the wearer, which are then attached to a waist band through four straps. A motor then “shoots” or “zaps” energy into the ankle joints of the wearer, so that the “resulting force and movement mimic the natural leverage of a natural stride.” This has the effect of dramatically cutting the amount of energy the wearer needs to use in order to move their feet forward.
The researchers found that the suit reduced the amount of work that the hip and ankle needed to do, thus putting less strain on the muscles. From this perspective, it is easy to see how it might help those with mobility problems. The fact that the exosuit is also soft and flexible means that it's well suited for this application too, when compared to the more rigid and mechanical iterations of exosuits previously tried.
“When you first start wearing it, it takes a while to get used to the assistance,” Walsh told New Scientist. “When you really notice it is if you turn it off very quickly. Your legs feel a little bit sluggish because your muscles were doing less work than you were used to.”
The study is helping researchers to find a “sweet spot” between how much the suit weighs and how much extra force it can deliver to the wearer in order to make the most efficient kit possible.