Research On External Track Geometric Parameters Measurement Based On GPS

With the rapid development of China’s high-speed railway, track regularity plays an important role in safety operation. Strengthening the detection technique of track parameters and maintenance has far-reaching significance in railway modernization. By dint of an analysis of domestic and international research, a system of external track geometric parameters measurement based on GPS is put forward, with an analysis and study about its key technologies. A fast track detection system is presented, offering a new idea for track maintenance. Main contents of this thesis are as follows:A summary of the basic theory of GPS is made, and a basic structure for detection system combined with track detection technology is designed, including inspecting instrument, GPS network and data transmission. Then a study of the operating principle of internal and external track geometric parameters measurement is presented.The basic factors and the construction of GPS network are analyzed; also the network error model is established through network adjustment. After summarizing and analyzing different parts of building control networks, a proper design can be chosen.Sources of RTK measurement errors are studied in order to achieve fast and accurate positioning results. What’s more, in an attempt to weaken influence from errors, frequently-used differential positioning methods for integer ambiguity solution are studied by comparing the measurement efficiency and accuracy of them, thus determining the error processing method based on LAMBDA algorithm.Static error and dynamic accuracy of GPS network are acquired through numerical examples, which prove the feasibility of the system. The new detection system can basically achieve the required accuracy, greatly improve the rail detection speed and has a good prospect in application.