Estimation of Rail Irregularity by Axle-Box Accelerometers on a High-Speed Train

This paper is focused on the rail irregularity estimation from axle-box vibration of an in-service high-speed train. Usually, the rail irregularity has been measured by a special railway inspection system during maintenance work. However, the procedure requires some mechanical or optical sensors that are sensitive to harsh railway environments, and it is too slow for in-service trains. Therefore, the procedure has to be performed in limited time and track sections. As a solution to this problem, measuring axle-box acceleration is proposed to estimate the lateral and vertical rail irregularities. For reliable estimation of displacement from the measurement, a method based on a Kalman filter and wavelength band-pass filters is proposed. The estimated results are compared with a railway inspection system. It is confirmed that the proposed method can provide useful rail estimates without any mechanical or optical sensors.