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R_www.dailymail.co.uk_sciencetech 2015 05160.txt.txt

#Move over Mother Nature! Insect-sized Robobee can fly, dive AND swim Bees may be capable of performing airborne acrobatics, but they can't swim underwater. In an improvement on Mother Nature's design, US engineers have created a'Robobee'that is able to dive and swim. The invention could pave the way for the development of'flying submarines'-vehicles that can seamlessly travel through air and water -which have been a dream for decades. Engineers at Harvard's John A Paulson School of engineering and Applied science (Seas) have been working on the Robobees for several years. The microbot is smaller than a paperclip and is able to fly and hover like an insect by flapping its tiny, nearly invisible wings 120 times per second. It is powered and controlled using a lightweight tether wire and can perform agile manoeuvres like insects, finding its balance thanks to a pyramid-shaped light sensor on top of its'head'.'Perhaps surprisingly, the researchers were inspired not by another insect to make the latest modifications to the design, but the puffin. The birds are one of nature's most adept hybrid vehicles and use similar flapping motions to the robots to propel themselves through air as well as water.''Through various theoretical, computational and experimental studies, we found that the mechanics of flapping propulsion are actually very similar in air and in water, 'Kevin Chen explained.''In both cases, the wing is moving back and forth. The only difference is speed the at which the wing flaps.''In order to make the transition from air to water, the team first had to solve the problem of surface tension. The Robobee is so small and light it couldn't break the surface tension of the water at first. But the researchers worked out a way of making it hover over the water at a certain angle, before momentarily switching off its wings, to overcome the problem. By doing this, the Robobee is able to crash into the water in a controlled way and sink.''Water is almost 1, 000 times denser than air and would snap the wing off the Robobee if we didn't adjust its flapping speed, 'said Farrell Helbling, the paper's second author. To overcome this obstacle, the team team lowered the wing speed from 120 flaps per second to nine for swimming, but kept the flapping mechanisms and hinge design the same. This means a swimming Robobee can change direction by adjusting the stroke angle of the wings, the same way it does in the air. Like the original flying version, the tiny drone has to be attached to a power source as it is too small to house a battery. The team prevented the Robobee from short-circuiting in the water by coating the electrical connections with glue. It also only currently swims in deionised water. Another drawback, is that as yet, the robot can't make the transition from water to air, because it can't generate enough lift without snapping one of its wings. Solving this issue is the next challenge.''What is really exciting about this research is that our analysis of flapping-wing locomotion is limited not to insect-scaled vehicles, 'Chen said.''From millimetre-scaled insects to metre-scaled fishes and birds, flapping locomotion spans a range of sizes. This strategy has the potential to be adapted to larger aerial-aquatic robotic designs.''Robert Wood, the Charles river Professor of Engineering and Applied sciences At seas added:''Bioinspired robots, such as the Robobee, are invaluable tools for a host of interesting experiments--in this case on the fluid mechanics of flapping foils in different fluids.''''This is all enabled by the ability to construct complex devices that faithfully recreate some of the features of organisms of interest.''The research was presented at the International Conference on Intelligent Robots and Systems in Germany y

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