Fast fiber coupled clearance profile scanner using real time 3D data processing with automatic rail detection

This article reports design and measurement results of a novel 3D laser measurement system delivered to SBST, Singapore, in February 2003. According to our knowledge, it is the first fast laser scanning system worldwide using optical fibers to separate the laser scanner from the temperature sensitive measurement electronics. Together with an angle encoder triggered measurement electronics the result is a simple and robust scan hardware, because no temperature control is needed since all sensitive parts can be mounted inside of the vehicle. The second feature of the system is an automatic alignment of the 3D laser scanner data with the rails. Therefore no additional information about the position of the vehicle towards the rails or about the track is necessary. The rail detection algorithm is executed in real time on a dual Pentium computer. The overall measurement accuracy under normal environment conditions is 3 to 10 mm standard deviation for distances up to 10 m.