marketed by Bionic Power, headquartered in British Columbia, Canada, harvests energy from knee motion, which is a source of “negative work” as the “pendulum” process involved in walking cycles energy between potential and kinetic. Figure I-3 shows a Bionic Power system intended for military use. By carefully controlling the point in the walking cycle where energy is harvested, the manufacturer claims that its technology has minimal effect on locomotion and fatigue of the wearer.

The performance of the Bionic Power system is as follows:

   Nominal power output: 8-14 W (1.5 m/s walking speed, level ground).

   Maximum power output: 25 W (15 degree down slope).

   Effort setting: 10 levels.

   Output voltage: 5 V to 16.8 V (2 to 4 Li ion cells).

   Maximum output current: 5 A

   Battery chemistries supported: lithium ion (others available upon request).

   LCD indicator: charge complete, charging, fault, output power.

   Connections: left leg, right Leg, battery.

   Fault Protection: Reverse polarity, open/short circuit, over/under voltage, temperature faults.

   External power input: 8 V to 24 V: Solar, vehicle, fuel cell.

   Operational speed: 0.5 to 3 m/s (slow walk to fast jog).

image

FIGURE I-3. Harvest of biomechanical energy. SOURCE: Reprinted with permission from BionicPower™. Available online at http://bionic-power.com/powerwalk_photos.html.



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