The difficult thing about wearing Harvard University engineer Conor Walsh’s robotic exosuit— a soft textile garment designed to enhance a human’s natural mobility—-isn’t putting it on. It’s taking it off.
When a test subject dons the waist-down outfit and attaches the battery pack to his waist, a gradual force begins to assist his leg muscles in movement, supplementing his power up to 20%. "You actually don’t really notice that it’s helping you. But as soon as you turn the system off, it makes you instantly feel that your legs are heavy, which shows that your legs have adapted," says Walsh, who heads Harvard’s Biodesign Lab.
The system is the latest prototype of a wearable robotics project being developed at Harvard’s Wyss Institute for Biologically Inspired Engineering. If all goes according to Walsh’s vision, the smart suit could one day assist soldiers and firefighters in carrying heavy loads, help stroke victims recover their movement and the elderly avoid falls and injuries, and even give a boost to everyday outdoor enthusiasts who want to hike longer.
Most people think of robots as standalone machines. But the growing field of wearable robotics aims to give human bodies themselves superhuman abilities. Companies like Ekso Bionics, for example, are developing exoskeletons towards this aim, many working under DARPA’s "Warrior Web" program.
Walsh’s suit—now funded with a new $2.9 million DARPA grant—is similar, but it’s also unique. Other systems in development are heavy and rigid, like skeletons, so they can provide the support needed to perform miracles like helping the paralyzed walk again. The soft exosuit uses a different a completely different design approach: It’s lightweight, flexible at the joints, and intended to be worn underneath clothing by healthy people or those needing smaller levels of assistance.
"We’re fundamentally addressing a different challenge," says Walsh. His team includes engineers and roboticists, but also apparel designers. And he's also inked a new R&D collaboration deal with the Boston-based sports company New Balance.
The suit works by mimicking the action of the leg muscles and tendons when a person walks, with an actuator system giving small, carefully timed assistance at the ankle and hip joints without restricting the wearer’s movement. The breakthrough is in the "structured functional textiles" that transmit those applied forces all over the body during natural movement. Wearable, flexible sensors integrate into the fabric to gauge the body’s movement and provide support at the right moment.
The biggest challenge in the two-year project has been making the exosuit lightweight enough to use. The first prototype was a big air-powered compressor that was too heavy to wear and had to be mounted to a treadmill. As can be seen in the video above, the current prototype is only six kilograms, with most of the weight in the battery and actuation system supported at the hip. It can be used two to four hours on a charge. It’s never going to be the Iron Man suit without a limitless power source, says Walsh, but already the current version is practical.
To date, Walsh has held more than 200 user development sessions, many at Wyss’s motion capture lab. Going forward, the focus will be on doing biomechanics studies to fine-tune the best ways and timing to apply force in different real-life scenarios. One big question that remains to be answered is how people will interact with the machines.
"We don’t know if the person uses that extra assistance so they can go faster, or if they say, okay, I can walk at my happy, normal pace and just use a little less effort," says Walsh. "Early evidence is showing that the underlying muscles take the assistance and decide to do less work. ... You’re not necessarily making them jump higher or run faster, you’re helping them perform over a long period of time."
As part of the DARPA program, the soft exosuit is traveling to the Army Research Lab in Maryland for performance testing with six soldiers. The team is also starting to recruit hemiparetic stroke patients, firefighters, and others who might find useful applications. The involvement of New Balance suggests exosuits could one day in the far future be a part of everyday sports wear. "Is City Sports ever going to sell a robot?" asks Walsh. "That’s not entirely clear. I think what we’re developing are a lot of very interesting possibilities."