The buzzing sound coming from one Harvard lab isn’t a fly infestation but rather a tiny, insect-like robot. The approximately penny-sized robot dubbed RoboBee mimics the aerial prowess of houseflies, one of the most agile fliers on Earth. And like a fly, RoboBee features two independently flapping wings that allow it to hover or perform basic controlled flight maneuvers.
“This is the world’s first demonstration of a fully unconstrained flapping wing insect-scale robot,” says Kevin Ma, a doctoral student at the Harvard University Microrobotics Laboratory and lead author of a paper published this week in Science describing the machine. While small helicopters and hummingbird-size flapping robots exist, Ma says, those creations are around ten times the size of the RoboBee.
“We’re very impressed by the maneuverability and agility that [insects] like bees and flies share,” he continues. “One day, a robot like this could afford us that same agility and maneuverability.”
Manufacturing lessons from origami
The RoboBee’s size, on the order of millimeters to centimeters, originally put it in an awkward position for manufacturing. Conventional manufacturing processes rely upon nuts and bolts, but such objects are much too large to be useful at the insect-scale. At the other extreme, nanometer- and micrometer-sized technologies are too small to apply to the RoboBee. To get around this hurdle, the interdisciplinary research team created their own technologies.
“The basic concept behind it is that it’s easier to make 2-D structures and fold them into 3-D structures than to make 3-D structures directly,” Ma says, comparing the methodology to origami or a child’s pop-up book. “The folding idea was the crux of the manufacturing technique that we used.”
The team used sheets of laser-cut materials folded into a thin body to form the robot’s electromechanical structure. Lightweight ceramic strips called piezoelectric actuators power its wings, which flap when the actuators convert electric charge into mechanical action. RoboBee consumes about 19 milliwatts of electricity during flight, and its wings move almost invisibly, flapping about 120 times per second.
In previous versions of the robotic fly (this work builds upon about a decade of research), the wings could not flap independently. The engineers have been able to overcome that obstacle and can now steer and stabilize the robot in the air.
A miniaturized battery and sensors will need to be incorporated into the tiny machine in order to give it full autonomy and freedom, however. For now, it gets power from a short tether. Because of the need to incorporate batteries and electronics, Ma thinks that the RoboBee, or perhaps something slightly larger, will likely be about the minimum size limit for a fully autonomous, wireless flying machine.
Once the technological hurdles have been beat, the RoboBee could be used for atmospheric monitoring of trace chemicals, search and rescue in collapsed buildings or other dangerous environments, spying and reconnaissance, or serve in swarms as agricultural crop pollinators.
Ma emphasizes, however, that his main motivation for undertaking the project was to pursue his scientific curiosity. He hopes his team’s creation likewise inspires others to get involved in basic research. “All of these techniques we’re developing, a whole suite of things, have applications in other fields, like for medical devices,” Ma says. “We imagine that this robot is great for outreach and for inspiring a new generation of engineers and scientists.”
Top Image: Five individual robotic flies of identical design are shown alongside a U.S. penny for scale, demonstrating that the manufacturing process facilitates repeatability and mass production. Image courtesy Kevin Ma, Pakpong Chirarattananon.