ENGINEERINGNET.EU -- Extremely fast and precise, it is able to spatially measure and monitor the position of the contact wire or the track from a train travelling at up to 100 kilometers (62 mph) per hour. If the scanner is stationary, it can capture passing trains and check for loads that might have slipped.
The laser beam is very rapidly switched on and off – modulated, as scientists would put it. The time shift of this modulation wave can be determined more quickly and precisely than is possible with a single laser pulse.
The system measures, by default, one million times per second. “For Deutsche Bundesbahn, we equipped a measurement train that scans the surroundings of the test track, using several laser beams and which delivers, taking four million measurements per second, a 3D image of what it scans”, explains Harald Wölfelschneider. That allows even small obstacles and constrictions to be detected, or we can plan the route via which a heavy load can best be transported to its destination.
Another field of application is the measuring of passing trains. This requires the scanner to be permanently mounted, which, however, does increase the chance of someone looking into the laser beam for a longer period. To make the scanner safe for the human eye, the researchers had to develop a new wavelength range: infrared, which is harmless for our eyes.
The team at IPM has also developed a 3D scanner, safe for the human eye, which is mounted onto a moving car and which scans the road from a height of about three meters. “We can now detect height differences of even 0.2 millimeters on the road, even at speeds of 80 kilometers per hour (approx. 50 mph)”, says Höfler. The scanner is to detect lane grooves, potholes and water drainage potentials.
Dr. Heinrich Höfler and Dipl.-Ing. Harald Wölfelschneider will receive one of the 2012 Joseph-von-Fraunhofer awards for this eye-safe 3D laser scanner.
(KV) (foto Fraunhofer)
