Compact laser system scans road surfaces at 100 km/h
May 1, 2013
Researchers at the Fraunhofer Institute for Physical Measurement Techniques have come up with a car-mounted laser scanner the size of a shoe box, that can survey the contours of road surfaces at speeds of up to 100 km/h (62 mph). The system detects potholes and other road damage in need of repair. According to the Institute, the Pavement Profile Scanner (or PPS) has surveyed 15,000 km of road since mid-2012, in which time it has proven cheaper, faster and more accurate than existing systems which require hefty attachments to the carrier vehicle.
An octagonal mirror housing scatters the laser light across the width of the road. With a 70º acquisition angle, the system can scan roads up to 4 m (13 ft) wide. By recording the time it takes for the laser to return to the scanner from the road surface, the distance at any point can be calculated; to an accuracy between 0.15 and 0.3 mm in the case of PPS. The only other information needed is the vehicle's position and orientation as a reference for each datapoint. It's LIDAR, basically.
It is hoped that PPS and similar system could save authorities significant amounts of money by catching superficial road damage before underlying layers are affected. Fraunhofer asserts that roads amount to over 60 percent of the capital assets of many towns and cities in Germany.
Though the technology is still in development, it has already met the safety requirements of The Federal Highway Research Institute. "It not only had to be accurate to 0.3 millimeters, it also had to be safe for the eyes," said Dr. Dirk Ebersbach, CEO of Lehmann + Partner, which conducted the road surveys. "This means that even if someone ended up looking into the laser for longer than necessary, it would not put their eyes at risk. The development partners' technology easily cleared both hurdles."
The current system operates at a frequency of 1 MHz, so it's capable of taking 1 million measurements every second. With the prototype now in development, the researchers have upped the frequency to 2 MHz. This should be enough to detect cracks in the road surface, which could allow road maintenance crews to prevent subsequent damage at an even earlier stage.
As we've reported previously, auto makers are also turning to LIDAR to help with the development of autonomous cars.