Unraveling a Butterfly’s Aerial Antics Could Help Builders of Bug-Size Flying Robots

Phil Sneiderman
February 2, 2012

To improve the next generation of insect-size flying machines, Johns Hopkins engineers have been aiming high-speed video cameras at some of the prettiest bugs on the planet. By figuring out how butterflies flutter among flowers with amazing grace and agility, the researchers hope to help small airborne robots mimic these maneuvers.

U.S. defense agencies, which have funded this research, are supporting the development of bug-size flyers to carry out reconnaissance, search-and-rescue and environmental monitoring missions without risking human lives. These devices are commonly called micro aerial vehicles or MAVs.

“For military missions in particular, these MAVs must be able to fly successfully through complex urban environments, where there can be tight spaces and turbulent gusts of wind,” said Tiras Lin, a Whiting School of Engineering undergraduate who has been conducting the high-speed video research. “These flying robots will need to be able to turn quickly. But one area in which MAVs are lacking is maneuverability.”

To address that shortcoming, Lin has been studying butterflies. “Flying insects are capable of performing a dazzling variety of flight maneuvers,” he said. “In designing MAVs, we can learn a lot from flying insects.”

Lin’s research has been supervised by Rajat Mittal, a professor of mechanical engineering. “This research is important because it attempts to not only address issues related to  bio-inspired design of MAVs, but it also explores fundamental questions in biology related to the limits and capabilities of flying insects,” Mittal said.

To conduct this study, Lin has been using high-speed video to look at how changes in mass distribution associated with the wing flapping and body deformation of a flying insect help it engage in rapid aerial twists and turns. Lin, a junior mechanical engineering major from San Rafael, Calif., recently presented some of his findings at the annual meeting of the American Physical Society’s Division of Fluid Dynamics. The student also won second-prize for his presentation of this research at a regional meeting of the American Institute of Aeronautics and Astronautics.

“Ice skaters who want to spin faster bring their arms in close to their bodies and extend their arms out when they want to slow down,” Lin said. “These positions change the spatial distribution of a skater’s mass and modify their moment of inertia; this in turn affects the rotation of the skater’s body. An insect may be able to do the same thing with its body and wings.”

Butterflies move too quickly for someone to see these wing tactics clearly with the naked eye, so Lin, working with graduate student Lingxiao Zheng, used high-speed, high-resolution videogrammetry to mathematically document the trajectory and body conformation of painted lady butterflies. They accomplished this with three video cameras capable of recording 3,000 one-megapixel images per second. (By comparison, a standard video camera shoots 24, 30 or 60 frames per second.)

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