Accuracy Analysis of Car Body-Mounted Doppler LIDAR Technology Used to Measure Track Speed and Curvature

Abstract

Modern track inspection technologies contribute to more efficient and reliable identification of track conditions including track geometry and sections requiring maintenance. Records of car body motion and rail conditions are also vital for derailment or track failure investigations. Doppler LIDAR technology is a tool with a vast array of utility in measuring speed of a moving target with a high degree of accuracy and precision, and has been proven by a Virginia Tech (VT) research team to record body motion and track curvature through car body speed characteristics. In the context of track maintenance, high sensitivity to rail surface deviations and signal fidelity at high speeds make LIDAR a desirable tool for collecting information on local curvature deviations and car body dynamic responses to such irregularities. Virginia Tech’s Railway Technologies Laboratory research team has completed extensive analysis on its Doppler LIDAR system’s ability to obtain train speed and track curvature profiles in terms of the system’s accuracy and dependency on car body motion during curve navigation. Due to the LIDAR system’s capability of providing curvature data from the speed profile, it follows that the LIDAR system also serves as a high-accuracy alternative to the geometry car’s IMU which also provides curvature data. Results show the LIDAR system records curves with a high correlation with ground truth measurements. The signal processing techniques used to reveal track curve and car body motion are reviewed to show that, indeed, the LIDAR system detects car body motion in addition to the track’s curvature profile. Results strongly suggest Doppler LIDAR serves as a high-accuracy alternative to multiple rail inspection instruments and provides useful data for the improvement of rail condition localization and mapping.