A biologically inspired smart suit that fits under clothing and could help soldiers walk farther, tire less easily, and carry heavy loads more safely is being designed by engineers at Harvard .
The lightweight Soft Exosuit overcomes the drawbacks of traditional, heavier exoskeleton systems, such as power-hungry battery packs and rigid components that can interfere with natural joint movement. It is made of soft, functional textiles woven into a piece of smart clothing that is pulled on like a pair of pants, and is intended to be worn under a soldier’s regular gear. The suit mimics the action of leg muscles and tendons when a person walks, and provides small but carefully timed assistance at the leg joints without restricting the wearer’s movement.
“While the idea of a wearable robot is not new, our design approach certainly is,” said Walsh, an assistant professor of mechanical and biomedical engineering at Harvard’s School of Engineering and Applied Sciences (SEAS) and founder of the Harvard Biodesign Lab.
In another application of soft robotics, Walsh’s team is also designing a fluid-powered glove for hand rehabilitation. Rather than use pulleys and cables, as in the exosuit, the researchers designed silicon-based inflatable tubes to mimic the motion of fingers. By wrapping the hollow elastic in thin fibers, they could control how the material stretched and curved when air or water was pumped into the tubes. That way, the material itself assumes the correct shape when pressurized, eliminating the need for complex mechanisms and control systems to recapitulate hand movements. “One of the advantages of these types of soft robots,” says Walsh, “is that you can design complexity into the structure to simplify the control requirements.” He imagines that the robotic glove could supplement physical-therapy exercises, aiding patients who have difficulties with motor control.
So far, the soft robots have been tested extensively on healthy people, and Walsh’s group is now beginning work with clinical partners to determine whether the glove and exosuit can help patients with disabilities. In the meantime, the team continues to refine its inventions. One major goal is improving the exosuit’s ability to monitor the wearer’s gait and accurately time its responses by embedding sensors along the length of the leg, rather than in the boot alone. The lab is also testing how the exosuit responds when the user travels over rough terrain, or walks at varying speeds.
For Walsh, the “soft robot” concept itself has been a major success. “To be able to show that we can actually make systems that can be functional, yet soft, is super interesting,” he says. “It opens lots of fundamental research questions that span materials science, robotics, and biomechanics.”