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Topic Name: 21st-century pack mule: MIT's 'exoskeleton' lightens the load

Category: Biomedical

Research persons: Hugh M. Herr, Ph.D.

Location: 77 Massachusetts avenue , Cambridge, Ma 02139-4307, United States

Details

Researchers in the MIT Media Lab's Biomechatronics Group have created a device to lighten the burden for soldiers and others who carry heavy packs and equipment.

Their invention, known as an exoskeleton, can support much of the weight of a heavy backpack and transfer that weight directly to the ground, effectively taking a load off the back of the person wearing the device.

In the September issue of the International Journal of Humanoid Robotics, the researchers report that their prototype can successfully take on 80 percent of an 80-pound load carried on a person's back, but there's one catch: The current model impedes the natural walking gait of the person wearing it.

"You can definitely tell it's affecting your gait," said Conor Walsh, a graduate student who worked on the project, but "you do feel it taking the load off and you definitely feel less stress on your upper body."

The research team was led by Hugh Herr, principal investigator of the Biomechatronics Group and associate professor in the MIT Media Lab. Earlier this summer, Herr and his colleagues unveiled the world's first robotic ankle for lower-limb amputees.

Eventually Herr hopes to create assistive leg devices that can be useful for anyone. Herr said he envisions leg exoskeletons that could help people run without breathing hard, as well as help to carry heavy loads.

"Our dream is that 20 years from now, people won't go to bike racks--they'll go to leg racks," he said.

Exoskeleton devices could boost the weight that a person can carry, lessen the likelihood of leg or back injury and reduce the perceived level of difficulty of carrying a heavy load.

The person wearing the exoskeleton places his or her feet in boots attached to a series of tubes that run up the leg to the backpack, transferring the weight of the backpack to the ground. Springs at the ankle and hip and a damping device at the knee allow the device to approximate the walking motion of a human leg, with a very small external power input (one watt).

Other research teams have produced exoskeleton devices that can successfully carry a load but require a large power source (about 3,000 watts, supplied by a gasoline engine).

When the MIT researchers tested their device, they found that although the load borne by the wearer's back was lightened, the person carrying the load had to consume 10 percent more oxygen than normal, because of the extra effort to compensate for the gait interference.

The team hopes to revise the design so the exoskeleton more closely mimics the movement of a human leg, allowing for more normal walking motion. The most important result of this study, says Walsh, is that the team's spring-based, low-energy design shows promise.

"This is the first time that it has been tested," he said. "We didn't know what to expect."

The research was funded by the Defense Advanced Research Projects Agency.

About Researcher:

Hugh M. Herr, Ph.D.
Associate Professor, Media Arts and Sciences
Assistant Professor, MIT-Harvard Division of Health Sciences and Technology
Director of the Biomechatronics Group
Email: Hherr@ai.mit.edu

Hugh Herr directs the Biomechatronics group at The MIT Media Lab:

His research program seeks to advance technologies that promise to accelerate the merging of body and machine, including device architectures that resemble the body's musculoskeletal design, actuator technologies that behave like muscle, and control methodologies that exploit principles of biological movement. His methods encompass a diverse set of scientific and technological disciplines, from the science of biomechanics and biological movement control to the design of biomedical devices for the treatment of human physical disability.

His research accomplishments in science and technology have already made a significant impact on physically challenged people. The Variable-Damper Knee Prosthesis has recently been commercialized by Össur Inc., and is now benefiting transfemoral amputees throughout the world. In addition, the Active Ankle-Foot Orthosis is now in the process of being commercialized, and has the potential for improving the quality of life of millions of stroke patients within the U.S. alone. Professor Herr's work impacts a number of academic communities. He has given numerous invited and plenary lectures at international conferences and colloquia, including the IVth World Congress of Biomechanics, the International Conference on Advanced Prosthetics, the National Assembly of Physical Medicine and Rehabilitation, the Highlands Forum XXII (Life Sciences, Complexity, and National Security), and the TEDMED International Conference. He is Associate Editor for the Journal of NeuroEngineering and Rehabilitation, and has served as a reviewer for the Journal of Experimental Biology, the International Journal of Robotics Research, IEEE Transactions on Biomedical Engineering, and the Proceedings of the Royal Society: Biological Sciences. He has been invited to participate in joint funding proposals from other universities and corporations, and has served on research review panels including the National Institute of Health, the National Institute on Disability and Rehabilitation, and the Department of Veterans Affairs. His work has been featured by various national and international media, including Scientific American Frontiers, Technology Review, National Geographic, and the History Channel.