Track inspection device mounted on commercial train for urban maglev

Track maintenance is very important in the public transport management activities and it requires a reliable track state database. As emerging rail transport, the maglev train lacks such a database. Special track inspection car can only work when traffic is stopped. In this way, the rail status collection efficiency is low and the maintenance cost is also increased. Track inspection device can be mounted on operational vehicles to collect large amounts of data through repeated measurements. So track inspection equipment requires good measurement repeatability. Since measurement results of track geometry are not variables, but random functions with respect to distance, the signal correlation coefficient is used to quantify the measurement repeatability; and the effect of train motion on measurement repeatability can be effectively assessed. Taking the vertical deviation measurement of the track as an example, the impact of the train motion (rolling, pitching, lateral vibrating and accelerating/ decelerating) on the measurement repeatability is analyzed in this study. Gyroscopes, inclinometers, lateral accelerometer and longitudinal accelerometer are installed on the instrumented bogie to sense the train motion. These sensor signals are then used to correct the vertical accelerometer, which help to improve the precision of the vertical acceleration signal. Thereby the measurement results won´t be affected by train motions, and the measurement repeatability can be improved. Test results show that the measurement repeatability has been improved 7%-43% after the multi-sensor correction technique is utilized.