Tiny Flying Robots Modeled on Insects
for National Geographic News
|March 13, 2003|
This is the second of a three-part series on how scientists are turning to nature to develop powerful new military technologiesthe subject of a new National Geographic EXPLORER documentary, Secret Weapons, premiering in the United States on MSNBC on Sunday, March 16, 8 p.m. ET/PT.
Black flies, wasps, and bumblebees may be the bane of backyard barbeques, but their keen ability to navigate from potato chip to hamburger to bare arm is the inspiration for a host of robots that may soon be hailed as international heroes.
Scientists from around the world are reverse-engineering the mechanics of insects as they design midget robots to scout battlefields, search for victims trapped in rubble, and record images as they hover over distant planets.
"Insect flight has many, many desirable features that, if we are able to mimic, we will be able to improve the performance of vehicles," said Kakkattukuzhy Isaac, a professor of aerospace engineering at the University of Missouri-Rolla.
These features include the ability to zero in and land precisely on a potato chip and then flap their wings to buzz off with blazing speed. While annoying to the person about to munch the chip, such insect maneuverability awes scientists.
Isaac and other researchers believe that robots inspired by the natural ability of insects will help them overcome several of the problems that hamper progress using traditional engineering methods.
"Some of nature's solutions are surprisingly simple and effective, and are not always dreamt up by engineering-style thinking," said Mandyam Srinivasan, a biologist at the Australian National University in Canberra.
Bug Vision and Flight
Srinivasan and his colleagues have spent the last 15 years sorting out how insects such as bees see with the acuity to allow perfect landings on the edge of a potato chip, despite the fact that the closeness of their eyes prevents them from seeing stereo imagery like humans.
To accomplish this, the insects use cues based on image motion to gauge the distances to objects. Srinivasan likens it to driving a car down a country highway. The trees at the side of the road whiz by, whereas the mountains on the distant horizon hardly move. The closer an object is to the observer, the faster it appears to move.
"The brains of insects measure the pattern of image motion and use it to perceive the world in 3-D to avoid collisions with obstacles and to perform smooth landings," said Srinivasan.
Since this method of vision is much simpler than processing images in stereo to see in three dimensions, it requires much less brain power, or in the case of robotics, a much smaller and relatively inexpensive computer. "Thus it allows us to devise autonomously navigating robots that are cheaper, simpler, smaller," said Srinivasan.
Srinivasan and colleagues have developed helicopters that use image motion to hover over an arbitrary set of landmarks. The next step in mimicking an insect is the development of flapping-wing flight.
Enter aerospace engineer James De Laurier and his team of researchers at the Institute for Aerospace Studies at the University of Toronto in Canada. In collaboration with SRI International in Menlo Park, California, they are developing ornithoptersaircraft that get all of their thrust and most of their lift from flapping wings.
They are building a robotic ornithopter named Mentor, whose design was inspired by the study of small wasps in 1984 at Cambridge University in England, where scientists revealed that the flapping motion of insects produces extraordinary lift for such small wingspans.
The same flapping action is also found in hummingbirds and quail, said De Laurier. However, Mentor looks nothing like any flying creatures, having two sets of flapping and clapping wings to provide side-to-side stability.
"Mentor holds promise of not only achieving hover, but of also transitioning into efficient high-speed horizontal flight," said De Laurier. "Airplanes don't hover well, and helicopters are speed-limited."
When complete, De Laurier and his colleagues envision the aircraft being sent on missions that are considered too dangerous for humans, such as surveillance of a building damaged by an earthquake or reconnaissance of a terrorist situation.
Engineers at the Georgia Tech Research Institute (GTRI) at the Georgia Institute of Technology in Atlanta, in collaboration with the University of Missouri-Rolla, NASA's Glenn Research Center, and the Ohio Aerospace Institute in Cleveland, Ohio are building a fleet of robotic bugs that will scout the landscape of Mars.
The robots, called entomopters, were first developed by engineers at GTRI under a grant from the Defense Advanced Research Projects Agency to fly inside buildings and caves. On Mars, the robots can take advantage of the unique mechanics of insect flight to overcome many of the obstacles that the low density and gravity of the Martian atmosphere present to conventional aircraft.
"Insects work completely different from aircraft or birds by formation and shedding of vortices each time they flap their wings," said Anthony Colozza, an aerospace engineer with the Glenn Research Center, who coordinates entomopter work at the Ohio Aerospace Institute.
Airplanes require velocity to generate lift, and so in the low density of the Martian atmosphere they would either have to fly very fast or have wings with very large surface area.
Current technology limits the size of package that humans can send to Mars, so the best way to achieve flight with a conventional aircraft is with high velocity, which makes it difficult to land or turn around to take a second look at something of interest, said Colozza.
The entomopter, which uses a two-wing design and a chemical concoction for fuel, can land with precision, buzz off with ease, and engineers are working on its ability to hover. And because of the low density of the Martian atmosphere, scientists can build a robotic insect that is several feet long and still have the stability of an insect on Earth.
"Because the atmosphere is so thin, a larger entomopter should fly as adeptly on Mars as its tiny Earth-bound cousins do in our denser terrestrial air," said Robert Michelson, a research engineer at the Georgia Institute of Technology who leads the entomopter research.
If NASA continues to fund this research, once complete the scientists envision entomopters working alongside a lander or rover, which could serve as a launching pad and a refueling station. The entomopters could then fly around and make images of points of interest, perhaps even landing at some to collect samples.
Entomopters are also potentially quite useful on Earth, said Michelson, who originally designed the two-winged aircraft to perform indoor reconnaissance missions for the military. One such use, he said, would be to look for Al Queda operatives inside caves.
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Use this National Geographic News article in your classroom with the Xpeditions lesson plan: Insects We Love and Hate
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