| The rapid development of high-speed railway has brought about the progress of the times.the track ride comfort and the safety of the train have attracted much attention.And this has prompted the track inspection technology to continue to update and become more mature.With the rapid development of global navigation satellite system(GNSS),it has penetrated into various application areas with the advantages of high precision and all-weather.The application of satellite navigation system to train positioning can give full play to outstanding advantages of satellite resources,break through many problems of track detection and can optimize the position service function of the railway system.Introducing GNSS into track inspection is expected to significantly improve the speed of track inspection.However,the accuracy of GNSS kinematic positioning is limited due to satellite error,receiver error and propagation error.The mature track inspection technology can provide accurate information about the internal geometric parameters of the orbit,which can provide accurate prior information or constraints condition for satellite positioning,and help to improve the accuracy of GNSS application in orbit measurement.The double difference model is often used in relative positioning,which can greatly weaken the influence of various public errors.However,in the application research of GNSS in rail transit,which has a large height difference span,the influence of tropospheric residuals can not be ignored.Therefore,this paper studied a kinematic relative positioning method that takes into account the constraint of track inspection information and tropospheric influence:This thesis summaries the methods of tropospheric delay estimation including several common models and several parameter estimation methods.Taking into account the complex operating environment of trains,the height difference span may be relatively large,the paper comes up with a method of single epoch estimation together with the coordinate parameters that the relative tropospheric delay between the reference station and the mobile station is considered as a parameter.From the experimental results,it is concluded that in the short baseline solution,it is better to not add tropospheric delay parameters if the height difference is small.The thesis studied a multiple antenna relative positioning method that track gauge information as the constraint condition,and derived a multiple antenna kinematic relative positioning model with track gauge constraint.From the analysis of some examples,the gauge information can better constraint the relative position of the GNSS antenna on thetrack inspection car.Compared with the unconstrained situation,the positioning accuracy is increased by 8.72% to 12.89%.The track constraint condition significantly improves the positioning results. |
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