| With the fast railway development in China,the high track smoothness required to maintain high-quality railway transportation is facing great challenges.Since the tamping machine is an essential large-scale road maintenance machinery,improving the accuracy of tamper track measurement parameters is of great significance to improve the tamper operation quality and meet the requirements of the track smoothness.At present,the tamping machine measures the track parameters by the string measurement method.The string material used in this method is steel wire rope,which will be worn and broken with the passage of time,and needs to be manually maintained and replaced.Currently,the sensor used in the measurement system is a mechanical sensor,which has some limitations in measurement accuracy and repeatability.The wire rope string will vibrate due to the tamper vibration during operation,resulting in unstable measured values.In response to the afore-mentioned weaknesses,it is proposed to replace the steel wire rope with laser.In the premise of avoiding the wire rope shortage,the use of laser for non-contact measurement can effectively reduce the error caused by contact measurement.And using the laser string to measure the track parameters has the advantages of high precision,fast measurement speed and convenient use.And the use of laser string measurement has the advantages of high precision,fast speed and convenient use.In this paper,it first introduces the principles of measuring track geometric parameters,and then according to the basic principle of the string measurement method,its transfer function is analyzed and calculated,then determines the scheme composition of the photoelectric measuring system.The photoelectric measuring system principle is obtained based on the measurement of track geometric parameters.Combined with the actual situation,the relationship between points B,C,and D and the length of the BD chord are selected to determine the measurement range and accuracy of the measurement system,and to propose requirements on the sensor accuracy and installation position according to the principle of error transmission.Second,after determining the range and accuracy of the measurement system,it performs reasonable selection of the light source,photoelectric detection device,image sensor acquisition card and inclination sensor in the hardware part according to the requirements.Then,the collected images are binarized,and the width of the sliding window and the threshold are determined by the combination of simulation experiments.After binarization,the light bars are filtered.Whether the center position of the light bar acquired by the CCD image sensor is correct will directly affect the accuracy of the photoelectric measurement system.In order to improve the accuracy of obtaining the center information of the laser light bar,the light bar image is processed by methods such as binarization,filtering,image enhancement and laser edge information determination.The calculated light bar center and the attitude angle information collected by the inclination sensor are output,displayed and saved after integration and filtering.Finally,it is verified through experiments that after being processed by the algorithm,the laser jumping mount is ±0.1mm in the outdoor static measurement.After moving a certain distance,the maximum difference between the photoelectric measuring system and the moving value measured by the vernier caliper is 0.1mm.Then,a section of onekilometer track is selected,where the photoelectric measurement system is used to compare with the original tamping machine string measurement system.The results indicate that the time responses of the two are basically the same,and the difference between the measured track longitudinal level does not exceed 0.5mm.This indicates that the photoelectric measurement system can provide a viable solution to the existing limitations of wire rope stringing and is of value for practical application in engineering. |
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