Research On Digital Track Map Generation Methods Towards Train Control Applications

With the development of train control system technology,Global Navigation Satellite Systems(GNSS)as input for “trainborne centric” localization,requires digital track map(DTM)as reference.This has become a key research point for train localization.The track geography information and topological relationship stored in DTM can effectively assist the train track occupancy identification and train integrity inspection.DTM is an important information source of train control system.DTM plays a key role in improving train localization accuracy,reducing operation cost and improving transportation efficiency.Therefore,the study on precise DTM generation method and the corresponding software(Track Map Composer,TMC)is of great significance.The main contents of the thesis include:(1)Studied the DTM model: According to the requirements of CTCS-N(Chinese Train Control System-New)for DTM,the model of digital track map based on the hierarchical structure is established,data and topological structure are analyzed,map model based on the XML format is applied,TMC software function requirements are proposed.(2)Studied the generation methods of DTM track geography information data.The data generation process is validity checking,interpolation,filtering and data reduction.To meet the data accuracy demand,3 data reduction algorithms are analyzed(Douglas Pecuker(DP),multiple-constraints reduction algorithm(MCR)and Clothoid curve based segmentation algorithm(CCS)).All 3 algorithms are applied for track line and curve expression,DP/MCR/CCS algorithm performances and parameters are evaluated.(3)Studied the validation methods of DTM.A two-dimensional table structure for map data object is designed,XML format is used for mapping the map data objects and XML nodes.To ensure the data integrity and consistency,XSD(XML schema definition)is used to conform a unique schema for XML data,the graph search algorithm verifies the topological consistency of the map topology.(4)Designed and developed the Track Map Composer(TMC).The software consists of four modules: data process module,data generation module,data organization module and data output module.The data process module implements and visualizes the map data processing flow;The data generation module generates the basic data for the formatted map;The data organization module realizes map data object organization,byte offset calculation and map validation;The data output module realizes the generation of map file in binary format.The thesis verifies the generation method of digital track map and the function of TMC software using the field collected from Beipiao east station to Fuxin north station,68 km line on the Jing-shen high speed railway.The results show that the maximum vertical deviation of DP reduction algorithm is 0.423 m,and the reduction rate is 99.3 %,which meets the requirements of map accuracy.In order to meet the requirements of line expression,the reduction rate of Clothoid curve based segmentation algorithm is 99.5 %,the maximum vertical deviation is 0.496 m,which has high reduction efficiency and accuracy.The integrity and consistency validation method proposed in this thesis can detect the errors of XML format map correctly.