Fly-sized robot takes first controlled flight

Washington: Harvard researchers have successfully designed, manufactured and flown a tiny fly-inspired aerial robot.

The demonstration of the first controlled flight of an insect-sized robot is the culmination of more than a decade's work, led by researchers at the Harvard School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering at Harvard.

"This is what I have been trying to do for literally the last 12 years," said Robert J Wood, principal investigator of the National Science Foundation-supported RoboBee project.

Inspired by the biology of a fly, with submillimeter-scale anatomy and two wafer-thin wings that flap almost invisibly, 120 times per second, the tiny device not only represents the absolute cutting edge of micro-manufacturing and control systems.

"We had to develop solutions from scratch, for everything.

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We would get one component working, but when we moved onto the next, five new problems would arise. It was a moving target," said Wood.

Flight muscles, for instance, don't come prepackaged for robots the size of a fingertip.

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"Large robots can run on electromagnetic motors, but at this small scale you have to come up with an alternative, and there wasn't one," said co-lead author Kevin Y Ma, a graduate student at SEAS.

The tiny robot flaps its wings with piezoelectric actuators - strips of ceramic that expand and contract when an electric field is applied.

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Thin hinges of plastic embedded within the carbon fibre body frame serve as joints, and a delicately balanced control system commands the rotational motions in the flapping-wing robot, with each wing controlled independently in real-time.

At tiny scales, small changes in airflow can have an outsized effect on flight dynamics, and the control system has to react that much faster to remain stable.

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The robotic insects also take advantage of an ingenious pop-up manufacturing technique developed by Wood's team in 2011.

Sheets of various laser-cut materials are layered and sandwiched together into a thin, flat plate that folds up like a child's pop-up book into the complete electromechanical structure.

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"We can now very rapidly build reliable prototypes, which allows us to be more aggressive in how we test them," said Ma.