Textile Insight

November / December 2017

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November/December 2017 ~ Textile Insight • 15 textileinsight.com arvard initially began its Exosuit project in 2012, with the goal of helping healthy people walk with less effort. "In 2014, we began exploring the possibility of adapting the technology for patients post-stroke," explains Conor Walsh, assistant professor of Mechanical and Biomedical Engineering, at the Harvard Biodesign Lab. Walsh and his team at the Wyss Institute for Biologically Inspired Engineering at Harvard anticipate a range of commercial applications from the research. The team has partnered with ReWalk Robotics on the medical version of the soft Exosuit. Through funding from DARPA (Defense Advanced Research Projects Agency), Walsh's team believes that a modified Exosuit could be used to help soldiers walk farther, carry more, and experience less fatigue. How the Exosuit Works The Exosuit delivers assistance to the wearer's muscles through a lightweight, non-restrictive cable system that provides motion for the ankle and the hip. The wearer utilizes a harness at the waist, with straps extending from the device to braces on each calf. The heavier components such as the motors and batteries are worn around the waist where it is easier to carry. A cable runs from the heel to a pulley at the calf, and then to a small motor. Gyroscopic sensors, mounted on the feet, send data to a microcontroller, which interprets the walker's stride and engages the motor. As the motor reels in the cable, it pulls on the heel, aiding the step. A waist-belt supports and minimizes pressure to the calf and assists the hip joint as the force from the pulley is transferred upward via the straps. The Exosuit also includes wearable sensors that monitor the movement of the person. The information, read by a small computer, is used to adjust the exact time for delivering assistance to the wearer as each step taken. Since weight is a concern, the Exosuit uses lightweight textiles attached to the wearer's legs that pull on cables attached to the ankle joint, which supports the wearer's movement. The team has been refining the textiles, the actuation systems, and the controllers to make the suits more realistic outside the lab. "It's a cross-disciplinary approach, featuring design and ergonomics, biomechanics, software engineering and robotics," explains Walsh. "Lightweight textiles and cables are attached to the legs to deliver assistance, and not alter the wearer's natural walking pattern. Since everyone walks a bit differently, the system must be at least partially customizable." The Exosuit materials include dimensionally-stable wovens, sail cloth, strategically-placed knits, and high-friction material panels. Sail cloth and other wovens ensure the transfer of forces on the body are as efficient as possible. Since humans are made up of different layers of tissues, stiff textiles help compress the tissues in a way that allows the application of high forces to the wearer's gait cycle. Knit materials with wicking and breathable properties allow the garments to fit different body types. High- friction materials anchor the device to certain body parts. Harvard Wyss Institute's research shows that a unilateral, soft wearable, robotic Exosuit can supplement the patients' partial paralysis, and the limb's ability to generate forward propulsion and ground clearance during walking. Walsh hopes that one day the Lab may be able to provide training in normal walking behavior after stroke. Walsh notes, "We see a range of commercial applications emerging from our research. Developing wearable robots or exoskeletons requires expertise from robotics, to apparel design to human biomechanics and physical therapy. Our team has all of these disciplines and we collaborate together to develop designs that can work synergistic with the wearer." O EDUCATION | HARVARD ReWalk Steps Up Research on a Wearable Robotic Exosuit Aids Post-Stroke Patients. By Kathlyn Sawantko For More Information For more information on the Exosuit research at the Wyss Institute for Biologically Inspired Engineering at Harvard University, contact Conor Walsh at: walsh@seas.harvard. edu, (617) 496-7128, or Diana Wagner at: Diana.Wagner@wyss. harvard.edu. Kathlyn Swantko, president of the FabricLink Network, created TheTechnicalCenter.com for Industry networking and marketing of specialty textiles, and FabricLink.com for consumer education involving everything fabric. Wearable Robotic Exosuit, developed by the Wyss Institute for Biologically Inspired Engineering at Harvard.

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