为了实时了解铁路轨道的轨距变化情况，研制了一种实时在线监测轨距变化的测量系统。采用位置敏感探测器和激光发射器作为测量元件实时采集轨距的变化信息，建立数学模型计算轨距的偏移量，通过组合算法来获取两根钢轨移动状态后的偏移量，并通过二次插值算法对位置敏感探测器进行非线性补偿以提高位置敏感探测器的精度和准确度；采用控制器局域网络总线和通用分组无线服务技术将一定区域内的轨距变化信息发送到监控中心进行显示；通过和现有二级铁路轨距尺分别对同一模拟轨道进行了测量实验。结果表明，该系统的测量精度为0.32mm，达到了目前轨道检测行业所规定的1mm精度要求。

In order to know the variation of rail gauge in real time, a real-time on-line gauge monitoring system was developed. Position sensitive detector and laser emitter was used as measuring elements for real-time acquisition of gauge change information. Mathematical model was established to calculate the offset of the gauge. The offset of two rails after moving was calculated by the combination algorithm. The position sensitive detector was compensated by quadratic interpolation algorithm to improve the accuracy and accuracy of position sensitive detector. The gauge change information in certain area was sent to the monitoring center for display by using controller area network bus and general packet radio service communication technology. The same simulation track was measured by the existing two-stage gauge gauge. The results show that, measurement accuracy of the system is 0.32mm. It meets the precision requirement of 1mm stipulated by track inspection industry at present.