Biomechanical Energy Harvesting: Generating Electricity During Walking with Minimal User Effort
J. M. Donelan,1*
Q. Li,1
V. Naing,1
J. A. Hoffer,1
D. J. Weber,2
A. D. Kuo3
We have developed a biomechanical energy harvester that generates
electricity during human walking with little extra effort. Unlike
conventional human-powered generators that use positive muscle
work, our technology assists muscles in performing negative
work, analogous to regenerative braking in hybrid cars, where
energy normally dissipated during braking drives a generator
instead. The energy harvester mounts at the knee and selectively
engages power generation at the end of the swing phase, thus
assisting deceleration of the joint. Test subjects walking with
one device on each leg produced an average of 5 watts of electricity,
which is about 10 times that of shoe-mounted devices. The cost
of harvesting—the additional metabolic power required
to produce 1 watt of electricity—is less than one-eighth
of that for conventional human power generation. Producing substantial
electricity with little extra effort makes this method well-suited
for charging powered prosthetic limbs and other portable medical
devices.
2 Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, PA 15213, USA.
3 Departments of Mechanical Engineering and Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
* To whom correspondence should be addressed. E-mail: mdonelan{at}sfu.ca
