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Only when the leg is moving from the back of the swing (when it's behind the walker) to the point where it steps on the ground, does the computer engage the generator. It's during this phase of walking that the leg muscles are working to slow the leg motion. Without the brace, this braking energy would be wasted. But with the brace, the kinetic energy is captured and converted into electricity. In experiments, Kuo and his team found that a person used up less body energy to produce a watt of electricity. "You're letting the generator be the break for you and because of that…you can get this electricity for free," said Larry Rome, professor of biology at the University of Pennsylvania in Philadelphia and inventor of Lightning Packs, backpacks that generate electricity while their wearers hike. Expending as little metabolic energy as possible can be critical for people, such as soldiers, working in remote places. They typically use, for example, hand-crank generators to produce electricity, but such a device can use up more than 6 watts of muscle energy just to generate one watt of electricity. If Kuo and his team want to improve upon their device, said Rome, they have three main challenges: Make the thing comfortable and lighter (right now it weighs 3.5 pounds). Use a more efficient generator and gear system. Design a component that can use the generated electricity to actually charge a battery. "You can't hook the battery up to the device without some other intervening electronics that control the charging." Kuo and his team are already looking forward to improvements, including making the brace more form-fitting and constructing it out of lightweight carbon-fiber material. Related Links: |
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