New Assistive Soft Exosuit Makes Walking 23% Easier
Exosuit is a wearable robot made of functional textiles, cable-based actuation, and a biologically-inspired control system. They directly target the ankle joints. Though researchers at Harvard Wyss Institute have been working on a soft Exosuit for years, they provided a proof of concept in 2016. Now the researchers disclose how much the suit can actually help its wearer through a recent study.
According to a new study published as a cover article in Science Robotics, Harvard's Exosuit reduces the energy a user needs to exercise while walking, by 23 percent. The test group comprised of seven healthy wearers. Targeting specific leg joints, the Exosuit aims to deliver assistance to people who carry heavy loads and for the disabled people. The suit is made of functional textiles, cable-based actuation, and a biologically-inspired control system.
[Image Source: Wyss Institute]
The researchers calculated the impact on wearer’s joints with light wearable textiles and pulling cables. In addition, they removed the actuation, electronics and battery units.
The team found that with increasing levels of assistance, the wearers considerably adapted their pace. However, most significant changes were at the ankle joint and at the hip. This is due to the additional straps coupling from back of the lower legs to the front of the hip.
The multi-faceted study was backed by the Wyss Institute for Biologically Inspired Engineering, the Harvard John A. Paulson School of Engineering and Applied Sciences. In addition, the Defense Advanced Research Projects Agency (DARPA)’s Warrior Web Program, the National Science Foundation, a Samsung Scholarship, the São Paulo Research Foundation and the Robert Bosch Stiftung.
Conor Walsh, a Wyss Institute Core Faculty member along with John L. Loeb Associate Professor of Engineering and Applied Sciences at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Founder of the Harvard Biodesign Lab, lead the team.
“In a test group of seven healthy wearers, we clearly noticed that the more assistance provided to the ankle joints, the more energy the wearers could save with a maximum reduction of nearly 23% compared to walking with the exosuit powered-off,” says Walsh. “To our knowledge, this is the highest relative reduction in energy expenditure observed to date with a bound exoskeleton or exosuit.”
“Other studies had stated that there can be an energy transfer between the ankle and other joints. However, by having a textile connect the ankle and hip with our soft exosuit, may have amplified this effect, providing to the considerable energy savings we found,” says Brendan Quinlivan, a graduate student who is working with Walsh. Brendan is also one of the first two authors on the study.
In addition, the authors acknowledge that further studies are required to compare the effects of fully body-worn versions. These studies quantify the impact of technology as the wearer carries the weight of the actuation and battery.
The Exosuit has several advantages when compared to a traditional exoskeleton. The worn part of the suit is extremely light. Moreover, the wearer's joints are unhindered by external rigid structures. Thereby the suit would have a minimum unintentional interference with the body's natural biomechanics.
“The results from this research will help us find a sweet spot between the added system weight and the amount of force applied to achieve maximum benefits in energy expenditure in wearers. Defining these interdependencies in healthy people will eventually also help us design versions suitable for people with walking abnormalities,” says Sangjun Lee. Sangjun is also a graduate student in Walsh’s team and a co-first author of the study.
“This study represents another major step forward along a path that will bring this new type of ‘wearable robot’ into the market where it will help soldiers and workers, as well as patients with disabilities,” says Donald Ingber, Wyss Institute Founding Director. Donald Ingber, M.D., Ph.D., is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and Professor of Bioengineering at Harvard SEAS.
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