Can a laser scanner drive a car?

Can a computer steer a car through a city without a driver’s help? The ‘Spirit of Berlin’, a vehicle developed jointly by researchers at the Fraunhofer Institute for Intelligent Analysis and Information Systems IAIS in Sankt Augustin and their colleagues at the Freie Universität Berlin, proves that it is possible.

The vehicle, which will be on display at this year’s Hannover Messe, made it to the semi-finals of the ‘DARPA Urban Challenge’ competition entirely alone –without a driver or a remote control. The Urban Challenge for unmanned vehicles is organized by the Defense Advanced Research Projects Agency (DARPA), the research arm of the United States Department of Defense. In November 2007, the third edition of the event was held at the site of a former air force base in California for the first time.

One of Spirit of Berlin’s most important sensors is a rotating 3-D laser scanner that was developed at the Fraunhofer IAIS. The scanner classifies the navigable route and is able to distinguish the street from footpaths, parking lots, houses and pedestrians. “The scanner, which is fixed to the roof of the car, constantly moves laser beams back and forth through a mirror on a vertical axis – it moves the laser beam from top to bottom and back again,” explains IAIS project manager Dr. Hartmut Surmann. “If anything gets in the way, such as a pedestrian, the laser beam is reflected and sent back to the scanner.

The software analyzes the information while the car is in motion and steers the vehicle in the right direction. The system comprises two back-to-back laser scanners that rotate in the same way as the flashing lights on police cars and are thus able to ‘see’ all of the car’s surroundings.” The lasers can record two complete images per second. One of the challenges involved is to keep adjusting the recorded values to allow for the distance covered. “At a speed of 36 kilometers per hour, the car moves 10 meters per second. Consequently, the measured data must constantly be adjusted to the car’s current position,” Surmann explains.

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