Precise corrugation measurement from moving platforms: Creating a virtual reference line by using acceleration sensors

Laser distance measurement systems such as triangulation sensors offer an accuracy in the range of several micrometers at a bandwidth of 10 kHz or even higher. Their speed is therefore sufficient to measure from moving platforms, but it is difficult or often impossible to guide the platform with a precision comparable to the measurement accuracy. To compensate this uncertainty of the relative position of the measurement system an acceleration sensor was used to establish a virtual reference line for the distance value measured. The first application was the corrugation measurement of the rail head with a spectral accuracy better than 10 mu m from a running train superimposed to a vertical movement of about 10 mm. Further applications might be pavement quality control or flatness control of any stationary object measured from a moving sensor.