Science often imitates life. Insects are common in the world. Tiny critters crawling and flying about. Now we are genuinely making them. In the very early hours of the morning, in a Harvard robotics laboratory last summer, an insect took flight. Half the size of a paperclip, weighing less than a tenth of a gram, it jumped up a few inches, hovered for a moment on fragile, flapping wings, and then sped along a preset route through the air. It was not science fiction, it was a man made fly.
Like a proud parent watching a child take its first steps, graduate student Pakpong Chirarattananon immediately captured a video of the fledgling and emailed it to his adviser and colleagues at 3 a.m.—subject line, "Flight of the RoboBee."
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," says Robert J. Wood, Charles River Professor of Engineering and Applied Sciences at SEAS, Wyss Core Faculty Member, and principal investigator of the National Science Foundation-supported RoboBee project. "It’s really only because of this lab’s recent breakthroughs in manufacturing, materials, and design that we have even been able to try this. And it just worked, spectacularly well."
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 represents the absolute cutting edge of micromanufacturing and control systems.
"We had to develop solutions from scratch, for everything," explains Wood. "We would get one component working, but when we moved onto the next, five new problems would arise. It was a moving target."
Flight muscles, for instance, don't come prepackaged for robots the size of a fingertip.
"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," says 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. Thin hinges of plastic embedded within the carbon fiber 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.
The next steps will involve integrating the parallel work of many different research teams who are working on the brain, the colony coordination behavior, the power source, and so on, until the robotic insects are fully autonomous and wireless.
The prototypes are still tethered by a very thin power cable because there are no off-the-shelf solutions for energy storage that are small enough to be mounted on the robot's body. High energy-density fuel cells must be developed before the RoboBees will be able to fly with much independence.
"Flies perform some of the most amazing aerobatics in nature using only tiny brains," notes coauthor Sawyer B. Fuller, a postdoctoral researcher on Wood's team who essentially studies how fruit flies cope with windy days. "Their capabilities exceed what we can do with our robot, so we would like to understand their biology better and apply it to our own work."
"This project provides a common motivation for scientists and engineers across the university to build smaller batteries, to design more efficient control systems, and to create stronger, more lightweight materials," says Wood.
For further information see Robot Flies.
Mech Bug image by Kevin Ma and Pakpong Chirarattanano via University of Harvard.