For centuries, humans looking to tame the skies have tried to mimic the movements of birds and insects. But engineers building flying machines have now found an unlikely muse: the ocean-dwelling jellyfish.
A tiny flying robot built at a lab in New York University mimics the gently puffing movements of the efficient swimmer's gelatinous bulb — not to paddle through water, but to stay aloft in air.
"Our [robot] is an aerial jellyfish if you will," Leif Ristroph, assistant professor of mathematics at NYU who designed the tiny machine, told NBC News. The four-winged robot is wire-connected to a power source. Like an umbrella, the robot's four wings collapse and open, "squirting" the air downward and allowing it to lift off.
"No one’s ever built this, and as far as we know nature never built it either to fly in air," said Ristroph, who was to present his design at the Fluid Dynamics Conference in Pittsburgh on Sunday. "Maybe that indicates that it’s a bad idea? In any case we got it to work, so maybe not that bad."
Water and air are both fluids, so the rules governing movement in either media are similar. Buoyancy helps stay afloat in water, but the real difficulty staying up in air is generating a lift to balance the body weight of the craft, Ristroph explained.
Other flying robots, like the tiny robotic bee built at Harvard's Wyss Institute, or the H2bird flapping-wing drone built at a lab at Berkeley, sense the direction and location and adjust their movements to stay in the air.
But Ristroph's pint-sized robots are "sort of dumb," he said. With no fancy sensors, the bots' physical design ensures that they stay upright just by opening and flapping their wings.
"That's the beauty of the design," Ristroph said, "It doesn't need a 'smart' design to help it recover."
Very tiny flying robots, each just centimeters across like his demo prototype, are best suited to adopt this spare design. And how might they ever be used? "[You'd] make a hundred of them and throw 'em up into the air and monitor the air quality above NYC — the pollutants or CO2," Ristroph said, making for a "nice peace-time application."