09 August 2002
09 August 2002
The micro-aerial vehicle is designed for brief, short-range flights controlled by the ordinary infantryman. The idea is that soldiers will carry several of the planes in their backpacks, deploying them as needed to scout for enemy troops that may be around the corner of a building or otherwise just out of eyesight.
""Soldiers can't carry around large surveillance aircraft. But they do need to look over the next hill,"" says Peter Ifju's of the University of Florida.
So-called ""micro-aerial vehicles,"" or MAVs, have been a hot area of research for several years. But Ifju's work is distinguished by his rapid progress. When he and the other UF researchers launched their efforts in 1997, the first plane they produced spanned 18 inches, weighed 10 ounces and was powered by a gasoline engine. Five years later, this small but otherwise unremarkable version of commercially available, remote-controlled planes has been completely transformed. Ifju's latest model: A 5-inch, lopsided oval-shaped craft equipped with a nearly silent electric engine. Even fully loaded with battery, video camera and transmitter, the plane weighs less than 2 ounces -- yet remains aloft for 10 minutes and ranges half a mile.
""Our goal has always been to build mission-capable airplanes,"" Ifju said. It is not far off. Ifju's planes have taken first place at the annual International Micro Air Vehicle Competition for the past four years, with his 5.5-inch video-equipped MAV setting a new record in April for surveying a target 600 meters, or nearly 2,000 feet, from the launch site. In other words, his planes are rapidly moving from science fiction to science fact. Military research agencies such as the Defense Advanced Research Project Agency have poured millions into micro-aerial vehicle research, much of it for unproven and exotic ""flapping wing"" technology. Ifju's planes, by contrast, are propeller-driven and funded in part by U.S. Army Special Operations, which hopes Ifju will develop a system that its soldiers can begin using within the next few years. (Ifju says he's less than five years away from that goal.) The National Science Foundation, the U.S. Air Force and NASA's Langley Research Center also have contributed to the UF effort, providing a total of about $500,000 so far.
Keeping practicality foremost, Ifju and his students are designing their MAVs to be both cheap and easy to make, so that they can be virtually disposable when deployed.
The skeleton of each plane consists of strands of carbon fiber, the same material used in tennis rackets and golf clubs. Latex rubber stretched over this skeleton forms the wings. A stick of gum-sized lithium-polymer battery, similar to that used in cellular phones, and the video transmitter both fit into the fuselage, which is made of clear plastic film. The pencil eraser-sized video camera lens pokes from the front of the fuselage. Each plane takes about five hours to build and costs $700, but $450 is for the video transmitter alone, Ifju said.
Flying the planes also requires a remote control, antenna and other hardware. Ifju and his colleagues have made the equipment portable, fitting it into a medium-sized plastic suitcase along with a catapult-like launcher, portable video player/recorder and virtual reality ""video glasses."" Made by Sony, the glasses reproduce the feel of watching a 52-inch TV from about six feet away. When connected remotely to the plane's camera, the glasses in effect place the pilot directly onboard the plane.
Ifju's biggest hurdle may be the laws of aerodynamics. Small airplanes are inherently less stable than large ones because they have much more drag than lift. As a result, flying the MAVs requires considerable skill and experience operating remote-controlled planes. Yet for the planes to be really useful, any soldier should be able to fly them.
To attack this problem, Ifju and a colleague, Michael Nechyba, an assistant professor of electrical engineering, are working on a computer program that will act as a kind of MAV autopilot. The program stabilizes the plane by identifying the horizon based on the information transmitted in the digital image, and preliminary tests have been promising.
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