Walk a mile in a robot’s shoes and it won’t feel so far. A new robotic “exosuit” cuts the energy a wearer uses to walk by 23 per cent – the highest reduction in energy expenditure for a suit powered by an attached cable.

The flexible, textile exoskeleton consists of two stretchy fabric wraps that go around the calves, a waist belt and four vertical straps running from calf to hip. A cable attached to a motor delivers force to the ankle so the wearer uses less of their own energy to lift and move the foot. This assistive power is also transmitted through the straps to the hip joint. This chain reaction means a separate motor is not needed at each joint.

At the moment, the exosuit is tethered to an external motor and has only been tested by wearers on a treadmill. Next, the researchers want to make a suit whose power supply is also worn on the body.

“Normally, muscles generate significant force, pulling on the lever at the joint, which pulls on the bone,” says Conor Walsh at the Harvard Biodesign Lab, who led the research. With the exosuit powered on, the work required at the hip and ankle is reduced.

“When you first start wearing it, it takes a while to get used to the assistance,” Walsh says. “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.”

A soft exosuit applies less force than a rigid exoskeleton, which is a better option for people who are fully paralysed or who need to carry extremely heavy loads. But the soft suit is easier to put on and adds little extra burden to its wearer.

This could make it ideal for people carrying more standard loads a long distance, such as soldiers.

It could also be used by those who find it hard to get around, says Walsh. “For a stroke victim or an elderly person, they can walk, but maybe not well,” he says. “Can we give them a little boost to help them move better or more efficiently?”

“The great benefit of the soft structure is you’re maintaining the biological alignment of the joint,” says Jeff Koller, who researches rigid exoskeletons at the University of Michigan in Ann Arbor. “You’re relying on the existing musculoskeletal structure of the user, and that’s been designed over millions of years of evolution.”

Source: New Scientist, Science Robotics