If you've ever swatted a mosquito away from your face, only to have it return again (and again and again), you know that insects can be remarkably acrobatic and resilient in flight. Those traits help them navigate the aerial world, with all of its wind gusts, obstacles, and general uncertainty. Such traits are also hard to build into flying robots, but MIT Assistant Professor Kevin Yufeng Chen has built a system that approaches insects' agility. Chen, a member of the Department of Electrical Engineering and Computer Science and the Research Laboratory of Electronics, has developed insect-sized drones with unprecedented dexterity and resilience. The aerial robots are powered by a new class of soft actuator, which allows them to withstand the physical travails of real-world flight.
Typically, drones require wide open spaces because they're neither nimble enough to navigate confined spaces nor robust enough to withstand collisions in a crowd. "If we look at most drones today, they're usually quite big," says Chen. "Most of their applications involve flying outdoors. The question is: Can you create insect-scale robots that can move around in very complex, cluttered spaces?" According to Chen, "The challenge of building small aerial robots is immense." Pint-sized drones require a fundamentally different construction from larger ones.
Insect-like drones have taken one large step closer to becoming a practical reality. Researchers at Harvard, MIT and the City University of Hong Kong have developed tiny insect-inspired drones that can not only maneuver in extremely tight spaces, but withstand bumps if things go wrong. The key is a switch to an actuation system that can flap the drones' wings while surviving its share of abuse. To date, drone makers wanting to go this small have had to ditch motors (which lose effectiveness at small sizes) in favor of piezoelectric ceramic-based rigid actuators. The new drones rely on soft actuators made from rubber cylinders coated with carbon nanotubes.
Kevin Chen, an assistant professor at the Massachusetts Institute of Technology, envisions a time when his insect-sized drone could be used as a search and rescue robot -- to find survivors in disaster debris that bigger drones couldn't reach. Kevin Chen, an assistant professor at the Massachusetts Institute of Technology, envisions a time when his insect-sized drone could be used as a search and rescue robot -- to find survivors in disaster debris that bigger drones couldn't reach. The reason it's so hard to kill a mosquito is that they move really well. Scientists are trying to build a robot with that kind of agility. And these tiny but mighty flying robots could be used in life-and-death situations, such as finding people in a collapsed building.
In the Harvard Microrobotics Lab, on a late afternoon in August, decades of research culminated in a moment of stress as the tiny, groundbreaking Robobee made its first solo flight. Graduate student Elizabeth Farrell Helbling, Ph.D.'19, and postdoctoral fellow Noah T. Jafferis, Ph.D. from Harvard's Wyss Institute for Biologically Inspired Engineering, the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), and the Graduate School of Arts and Sciences caught the moment on camera. Helbling, who has worked on the project for six years, counted down: "Three, two, one, go." The bright halogens switched on and the solar-powered Robobee launched into the air. For a terrifying second, the tiny robot, still without on-board steering and control, careened towards the lights.