Article

Biomechanical energy harvesting from human motion presents a
promising clean alternative to electrical power supplied by batteries for
portable electronic devices and for computerized and motorized prosthetics. We
present the theory of energy harvesting from the human body and describe the
amount of energy that can be harvested from body heat and from motions of various
parts of the body during walking, such as heel strike; ankle, knee, hip,
shoulder, and elbow joint motion; and center of mass vertical motion. METHODS: We
evaluated major motions performed during walking and identified the amount of
work the body expends and the portion of recoverable energy. During walking,
there are phases of the motion at the joints where muscles act as brakes and
energy is lost to the surroundings. During those phases of motion, the required
braking force or torque can be replaced by an electrical generator, allowing
energy to be harvested at the cost of only minimal additional effort. The amount
of energy that can be harvested was estimated experimentally and from literature
data. Recommendations for future directions are made on the basis of our results
in combination with a review of state-of-the-art biomechanical energy harvesting
devices and energy conversion methods. RESULTS: For a device that uses center of
mass motion, the maximum amount of energy that can be harvested is approximately
1 W per kilogram of device weight. For a person weighing 80 kg and walking at
approximately 4 km/h, the power generation from the heel strike is approximately
2 W. For a joint-mounted device based on generative braking, the joints
generating the most power are the knees (34 W) and the ankles (20 W).
CONCLUSIONS: Our theoretical calculations align well with current device
performance data. Our results suggest that the most energy can be harvested from
the lower limb joints, but to do so efficiently, an innovative and light-weight
mechanical design is needed. We also compared the option of carrying batteries to
the metabolic cost of harvesting the energy, and examined the advantages of
methods for conversion of mechanical energy into electrical energy.

Langue : ANGLAIS