Motorless Exoskeleton Carries 80 Pounds
From: NASA Tech Briefs Insider - 10/10/2007

Researchers at MIT have developed a leg exoskeleton that can carry 80 pounds
without using motors. The developers stated that the prototype can support
80% of this weight while using less than one-thousandth of a percent of the
power used by its motorized equivalents.  

Leg exoskeletons are intended to help people carry heavy loads, according to
Hugh Herr, director of the Biomechatronics Group at MIT and leader of the
research. These mechanical structures are designed to transfer much of the
load directly to the ground rather than to the walker's legs. Thus, soldiers
and firefighters can bear heavier loads while expending less energy and with
less risk of injury.  

Traditionally, exoskeleton research has focused on using costly,
energy-consuming, and noisy motors to carry these loads. The noise was a
particular problem in military applications, according to Conor Walsh, an MIT
graduate student who also contributed to the research.  

Walsh and fellow MIT graduate student Ken Endo developed a mechanical system
that mimics the movements and energy-storage capabilities of the wearer's
legs, thus reducing muscle work. They designed the exoskeleton with two
leglike mechanical structures that run parallel to the user's legs. These
structures have elastic energy-storage devices at the ankle and hip, and a
variable damping device at the knee joint.  

The structure is designed to prevent the knee from buckling under the weight
of the payload. While the design reduces the energy consumption to a fraction
of that of a motorized exoskeleton, it increases the user's metabolic rate,
because the device interferes with the natural gait of the walker.  

MIT researchers are seeking to optimize the spring properties to reduce the
energy the wearer needs to expend wearing the exoskeleton. So far, the group
has no specific plans to commercialize the technology.  

Read the entire article at:
http://web.mit.edu/newsoffice/2007/exoskeleton-0919.html

Links:
MIT Media Lab's Biomechatronics Group
http://biomech.media.mit.edu/index.html

Hugh Herr
http://biomech.media.mit.edu/people/herr.htm

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http://blogs.spectrum.ieee.org/automaton/2007/09/19/mit_robotic_exoskeleton_struts.html

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http://web.mit.edu/newsoffice/2007/robot-ankle-0723.html

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