A Laser Sensor-Based 3-Dimensional Displacement Measuring System for Railway Track

This paper presents the design of a laser measurement system for measuring the 3-dimensional(3D) displacement of railway track. The system consists of a three-channel laser sensor and a regular tetrahedral target. With three lasers, the sensor placed at a stationary position away from the railway track gets the 3-dimensional displacement of a target on the railway track. The structural displacement is computed in real time through processing the measured data. A clever conversion formula developed in this paper enables measurement of 3D displacement by tracking three sets of one-dimensional data of a target without vision technology. The efficacy of the laser system in 3D displacement measurement of the railway track was demonstrated through a fine-tuning table test. The maximum error is 1mm, which nearly equals to the accuracy of the laser sensor. An artificial means of marking the target is also proposed to further improve the adaptability of the system to the dark environment.