Development Of Integrated Displacement Measurement System For Closing And Creeping Of Switch Rail

Turnout is a vital part of the entire railway network,ensuring the smooth running of trains when turning.The closing and creeping displacements of switch rail affect the working condition of the turnout.Accurate access to the continuous closing and creeping displacements is important for the safe operation of the turnout.For this purpose,an integrated displacement measurement system for closing and creeping of switch rail is developed,which realizes the real-time monitoring of the orthogonal continuous displacements of the switch rail.The system structure is designed to facilitate the installation and protection of the sensing unit,which solves the problem of difficult installation of sensors in orthogonal direction and facilitates sensors protection,and ensures that the system can stably detect the closing and creeping displacements of switch rail for a long time under harsh environmental conditions.Firstly,according to the measurement target and measurement technical requirements,the key problems in the system development process are analyzed,and the overall measurement scheme of the system is designed.The closing and creeping displacements of switch rail are derived from the action guide rod which is hinged with the switch rail.The system converts the closing and creeping movements of the switch rail into rotation and rectilinear motions of the action guide rod through a rotating turret structure.According to the overall measurement scheme,a joint calculation model of closing and creeping displacements based on the combination of angular and linear displacements is established.The calculation model is based on rigid body transformation,and reversely solves the lateral and longitudinal displacements of the target,providing a theoretical basis for the calculation of the measurement system.And a field calibration method is proposed to calibrate the initial installation parameters of the system.Secondly,according to the overall measurement scheme of the system,the rotating turret structure of the system is divided into a displacement measurement module and an angle measurement module to complete the design of the overall mechanical structure of the measurement system.According to the measurement accuracy and working requirements of the system,the performance parameters of the angular and linear displacement sensors are determined.In order to realize the real-time measurement function of the system,the hardware circuit of the data acquisition and processing unit of the measurement system is designed.The hardware circuit selects STM32F103CBT6 chip as the main controller.The key chip components are selected,and the system power supply circuit,angular/linear displacement acquisition circuit,CAN communication circuit and wireless WIFI communication interface circuit are designed.In order to verify the functions of each hardware,the measurement system software is designed based on the idea of layers.The MCU program realizes the acquisition and decoding of each sensor data.The software programs of the PC and the mobile phone are developed,and the human-computer interaction software is reasonable and easy to operate,which is used for real-time data reception and display.The measurement experiment of the system is carried out to verify its actual measurement accuracy and stability.After the system calibration is completed according to the calibration method,the accuracy and repeatability measurement experiments are carried out on the system in turn.The experimental results show that the measurement repeatability of the system is 0.065 mm,the extreme value of the closing error is0.162 mm and the extreme value of the creeping error is-0.187 mm,which are within the range of ±0.2 mm and can meet the requirement of high-precision measurement for the closing and creeping of switch rail.As a result,this system provides an effective monitoring means for the safe operation of the turnout.