শুক্রবার, ২০ এপ্রিল, ২০১২

Drones for Science: The First Step in a Civilian UAV Invasion?

On a Utah plain with a backdrop of snow-covered mountains, Austin Jensen walks backward holding a bright red flying wing 6 feet across. When the bungee cord holding the airplane to a stake in the ground is taut, he holds the machine over his head and releases it into the sky. Propelled by the tension in the bungee, it sails overhead, releases from the bungee, and spins up the pusher prop in the back with a whine from its electric motor. The airplane climbs, banks, and flies away toward the mountains.

And so begins another mission of the AggieAir Flying Circus, a project of the Utah Water Research Laboratory, or UWRL, at Utah State University. For five years the group has been flying sorties of autonomous unmanned aerial vehicles (UAVs) on mapping and remote sensing missions over rivers, wetlands, crops, construction sites, and more. Now that the team has perfected autonomous flight and mapping, it is poised to take the next step: bigger airplanes flying in formation, sharing data in right, covering more ground in less time and at a fraction of the cost of traditional mapping and imaging services that rely on blimps and manned airplanes.

AggieAir?s half-dozen flying wings, all based on an off-the-shelf platform from Unicorn Wings, incorporate cameras?near-infrared and thermal as well as visible?GPS, computers, inertial measurement units (IMUs), and a sophisticated software package developed by the group to bring remote sensing services to conservationists and civil engineers. During a flight lasting up to an hour, an AggieAir vehicle autonomously overflies a target area according to a preprogrammed flight plan, at an altitude up to about 3000 feet. Jensen and his colleagues monitor the flight from a laptop in a nearby trailer, tracking airspeed (35 miles per hour is typical), altitude, progress along the flight path, and attitude. The aircraft takes a picture of the ground below every 4 seconds, flying back and forth as necessary to make a complete photographic map of the river, highway, or field it?s surveying.

After the machine flies itself in for a landing on its skids (it has no landing gear), the team retrieves it and pulls out a memory card to upload the images and other data. The individual images are already roughly georeferenced with the help of GPS and IMU data, with an accuracy of perhaps 30 feet in placement. But further processing, which takes a few hours, fine-tunes the location placement to within inches, allowing precise overlays on Google maps and fine measurements of individual features. Combining data gathered via the various types of cameras simultaneously yields information on soil moisture, the distribution of certain kinds of plants, and other features of interest.

"We can tell people now where they have Phragmites australis, this invasive reed species that?s taking over North American wetlands," UWRL director Mac McKee says. "We can tell them where they have Phragmites at 95 percent accuracy, and that?s about 20 percent better than commercial algorithms can do." Even better, since the UAVs are so much cheaper to fly than manned aircraft and so much easier to operate than balloons, successive missions can overfly the same regions over time to show changes in progress.

The AggieAir project is more than just a smart scientific tool that promises to bring near real-time remote imaging and sensing?capabilities until now available mainly to the military?to agriculture, land, and water conservation, civil engineering, and emergency response. It?s also a glimpse of the future of nonmilitary drones, and how the Federal Aviation Administration (FAA) will integrate them into civilian air space. AggieAir and other civilian UAV projects have to operate according to narrowly defined rules that prohibit commercial use, limit the altitude and range of single-vehicle flights, and restrict formation flights to military air space. Currently, then, civilian UAVs are the domain of researchers and hobbyists. But the coming drone invasion seems inevitable.

"We?re excited about a change in the rules," McKee says. "After now doing this for five years, I think it can be done safely, it can be done logically, and it can be done in ways that benefit our society in natural resources management areas, which is our specialty." The FAA is in the process of selecting six national test areas for learning how to incorporate UAVs into the mix of airliners, general aviation craft, and other manned vehicles that are a normal part of national airspace. It?s a first step toward a legal mandate that the FAA must integrate manned and unmanned civilian aircraft traffic by 2015.

For now, the Utah State team has two new types of UAVs in development. The larger version is called Titan. "[It?s] a dream," McKee says. "It simply wants to fly, and has just tremendous aerodynamic abilities." Titan would extend the maximum range for the AggieAir fleet to 50 miles, up from 30, and extend the maximum flight time from an hour to 80 minutes.

A vertical takeoff/vertical landing vehicle is also in the works. "We have the capability to fly them in a fleet and we have tested this in areas that allow this," McKee says. Under current FAA rules, UAVs are not permitted to fly in formations in normal air space. If and when that changes, the AggieAir Flying Circus will be ready. "We have tested some of the rudimentary capabilities for multiple aircraft flight and sharing the data collection assignment," says McKee, "and so far so good."

Michael Belfiore is the author of The Department of Mad Scientists: How DARPA Is Remaking Our World, from the Internet to Artificial Limbs and is a regular contributor to Popular Mechanics.

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