A high-precision online monitoring system for surface settlement imaging of railway subgrade

In order to improve the measurement accuracy of subgrade settlement deformation system, this study proposes a high-precision, online monitoring system for subgrade settlement imaging. Firstly, the working principle and key technologies of this system are introduced. Secondly, a pose measurement system is designed to solve the problem that the relative position of target and camera in the monitoring system is affected by train vibration, and attitude estimation method p4p(Perspective 4 Points) for rectangular four-feature points target is proposed. Finally, experimental results indicate that when the relative deflection angle is less than 2 degrees, the rotation angle error of pose measurement method in this study is less than 0.09 degrees. The measurement accuracy of this method meets the requirement of this online monitoring system. And on-site testing results illustrate that the monitoring system corrected by the pose measurement system avoids the detection of non-real subgrade settlement and improves the measurement accuracy. (C) 2020 Elsevier Ltd. All rights reserved.