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.
Video and color digital images of the butterfly research available; contact Phil Sneiderman.Related Links:
Johns Hopkins Department of Mechanical Engineering: http://www.me.jhu.edu/
How electric heating could save CO2 emissions
17.12.2018 | Technische Universität München
Data use draining your battery? Tiny device to speed up memory while also saving power
14.12.2018 | Purdue University
Researchers from the University of Basel have reported a new method that allows the physical state of just a few atoms or molecules within a network to be controlled. It is based on the spontaneous self-organization of molecules into extensive networks with pores about one nanometer in size. In the journal ‘small’, the physicists reported on their investigations, which could be of particular importance for the development of new storage devices.
Around the world, researchers are attempting to shrink data storage devices to achieve as large a storage capacity in as small a space as possible. In almost...
The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.
Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
17.12.2018 | Studies and Analyses
17.12.2018 | Life Sciences
17.12.2018 | Power and Electrical Engineering