Abstract:

In order to evaluate the accuracy of the multi-point laser-based rut depth measurement,first,an indoor rut pattern simulator was developed,and the point cloud data in the transverse section were measured by means of 3D laser technology.Next,by virtue of Matlab programming and fifth-order Butterworth low-pass filter,the rut transverse-section curves acquired by the uniform 9-point,13-point,21-point and the non-uniform 13-point lasers were simulated,respectively.Then,the wire line method was employed to calculate the maximum rut depth of 3D laser and multi-point laser.Finally,the influences of the laser point number and the layout scheme on the calculation error of U-shape and W-shape ruts with low and high severity were analyzed by taking absolute error and relative error as the evaluation indexes.The results show that ( 1) the depth calculation error of the two above-mentioned rut transverse sections gradually decrease with the increase of the laser point number; ( 2) the maximum relative errors of the uniform 9-point,13-point,21-point and the non-uniform 13-point lasers are 22. 9%,12. 8%,8. 3% and 16. 4%,respectively; ( 3) with the augment of rut severity,the absolute error increases gradually while the relative error declines; ( 4) the relative errors of the U-shape and W-shape rut depth calculation by using the non-uniform 13-point lasers are respectively 4. 8% and 2. 2% larger than those of the uniform 13-point laser; and ( 5) the absolute error of rut depth calculation via multi-point laser may cause the underestimation of rut severity level,which may result in the loss of perfect time for maintenance.

Key words: road engineering, rut depth, three-dimension laser, multi-point laser, error analysis