Unraveling a Butterfly's Aerial Antics Could Help Builders of Bug-Size Flying RobotsFebruary 03, 2012
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.)
The Johns Hopkins researchers anchored their cameras in fixed positions and focused them on a small region within a dry transparent aquarium tank. For each analysis, several butterflies were released inside the tank. When a butterfly veered into the focal area, Lin switched on the cameras for about two seconds, collecting approximately 6,000 three-dimensional views of the insect's flight maneuvers. From these frames, the student typically homed in on roughly one-fifth of a second of flight, captured in 600 frames. "Butterflies flap their wings about 25 times per second," Lin said. "That's why we had to take so many pictures."
The arrangement of the three cameras allowed the researchers to capture three-dimensional data and analyze the movement of the insects' wings and bodies in minute detail. That led to a key discovery.
Earlier published research pointed out that an insect's delicate wings possess very little mass compared to the bug's body. As a result, those scholars concluded that changes in spatial distribution of mass associated with wing-flapping did not need to be considered in analyzing an insect's flight maneuverability and stability. "We found out that this commonly accepted assumption was not valid, at least for insects such as butterflies," Lin said. "We learned that changes in moment of inertia, which is a property associated with mass distribution, plays an important role in insect flight, just as arm and leg motion does for ice skaters and divers."
He said this discovery should be considered by MAV designers and may be useful to biologists who study insect flight dynamics.
Lin's newest project involves even smaller bugs. With support from a Johns Hopkins Provost's Undergraduate Research Award, he has begun aiming his video cameras at fruit flies, hoping to solve the mystery of how these insects manage to land upside down on perches.
The insect flight dynamics research was funded by the U.S. Air Force Office of Scientific Research and the National Science Foundation.
Johns Hopkins University
Related Butterflies Current Events and Butterflies News Articles
Color-coding sensor: Nanostructures for contactless control
Chemists at Ludwig-Maximilians-Univeristaet (LMU) in Munich have fabricated a novel nanosheet-based photonic crystal that changes color in response to moisture. The new material could form the basis for humidity-sensitive contactless control of interactive screens on digital devices.
Maternal experience brings an evolutionary advantage
Using a species of butterfly as an example, researchers from the Department of Environmental Sciences at the University of Basel have demonstrated how insects adapt their offspring to changing environmental conditions.
Naturally occurring 'GM' butterflies produced by gene transfer of wasp-associated viruses
Research teams from the University of Valencia and the University of Tours have discovered that genes originating from parasitic wasps are present in the genomes of many butterflies.
Family tree for orchids explains their astonishing variability
Orchids, a fantastically complicated and diverse group of flowering plants, have long blended the exotic with the beautiful.
Severe droughts could lead to widespread losses of butterflies by 2050
Widespread drought-sensitive butterfly population extinctions could occur in the UK as early as 2050 according to a new study published today in the scientific journal Nature Climate Change.
Genetic study of 'co-evolution' could provide clues to better food production
In 1964, renowned biologists Peter Raven and Paul Erhlich published a landmark study that introduced the concept of co-evolution.
Staying cool: Saharan silver ants
Nanfang Yu, assistant professor of applied physics at Columbia Engineering, and colleagues from the University of Zürich and the University of Washington, have discovered two key strategies that enable Saharan silver ants to stay cool in one of the hottest terrestrial environments on Earth.
Researchers discover first sensor of Earth's magnetic field in an animal
A team of scientists and engineers at The University of Texas at Austin has identified the first sensor of the Earth's magnetic field in an animal, finding in the brain of a tiny worm a big clue to a long-held mystery about how animals' internal compasses work.
'Vampire' plants can have positive impacts up the food chain
New research has revealed that parasitic 'vampire' plants that attach onto and derive nutrients from another living plant may benefit the abundance and diversity of surrounding vegetation and animal life.
Vineyard habitats help butterflies return
Washington wine grape vineyards experimenting with sustainable pest management systems are seeing an unexpected benefit: an increase in butterflies.
More Butterflies Current Events and Butterflies News Articles