Just like its insect role model, the robot uses four legs to propel its leap from either a solid surface or from water-but it does so using the energy stored in a spring-loaded device that mimics the action of a flea’s leg when it jumps.
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The artificial bug was a great demonstration of how modern technology can copy the principles of nature. Researchers from Harvard University and Seoul National University in South Korea studied live water striders, which can skate and leap on water, to design the robots. Previously, engineers have designed striderlike robots that can walk on water, too, but they’ve never been able to duplicate the insect’s ability to jump and escape (first 9 seconds of video, above)-until now.
The prototype robot weighs just two-thousandths of an ounce (68 milligrams) and has a body measuring 3/4-inch (2- centimeter) long.
A future robot that can float and jump on water could prove invaluable in surveillance work and to help find survivors after disasters. In their robot they used a torque reversal catapult (TRC) mechanism to generate a small initial torque and gradually increase, without exceeding the water’s surface tension. The robotic insects can jump as high on water as on hard ground.
The water strider, whose legs have slightly curved tips, employs a rotational leg movement to aid its takeoff from the water’s surface.
The researchers used this method to help their robotic insect successfully launch from the watery surface. Overall momentum is then maximized.
“Water’s surface needs to be pressed at the right speed for an adequate amount of time, up to a certain depth, in order to achieve jumping”, said the study’s co-senior author Kyu Jin Cho.
The robotic insect can exert up to 16 times its own body weight on the water’s surface without breaking through, and can do so without complicated controls.
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But they added their goal had been not to commercialise their miniature robot, but to explore “a new possibility [for] a robot’s aquatic mobility”.
