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Drive-by-Wire

In an ultimate example of "motion control," a team of Virginia Tech engineering and geography students have will compete in the national Urban Challenge autonomous vehicle competition sponsored by the Defense Advanced Research Projects Agency (DARPA). The team was one of only 11 "track A" teams chosen in 2006 to receive $1 million contracts to develop autonomous vehicles capable of conducting simulated military supply missions in an urban setting.

The team converted two Ford Escape hybrid SUVs into autonomous vehicles by outfitting them with a "drive-by-wire" system, a computer system, laser scanners, cameras, and a GPS (global positioning system). Urban Challenge vehicles must negotiate a 60-mile course through traffic in less than six hours with no human intervention allowed past the starting line. The vehicles must merge into moving traffic, navigate traffic circles, negotiate intersections, and avoid moving obstacles.

The drive-by-wire system allows the computers to control the throttle, brake, steering, and shifting, and to drive the vehicle. Laser scanners mounted on the bumpers and roof rack can detect large and small obstacles and the vehicle's blind spot when it changes lanes or merges into traffic. Two cameras on the roof rack enable the vehicle to sense its location, identify its proper position in the traffic lane, and identify another vehicle. The GPS has been designed to measure movement in all directions and to provide an accurate position, even if the GPS satellite signal is temporarily lost.

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