The Study On Video Metry System For Railway Geometry Parameters Measurement

Geometry parameters measurement is one of the most important tasks and preconditions in railway construction and maintenance. As the railway in our country develops towards high speed and heavy burden, the precision and efficiency of railway geometry parameters measurement needs to be on a high level. Existing methods have low precision and efficiency, and cann't keep up with the development of the railway. Video metry technique can solve these problems. In order to fill this demand, a video metry system is designed for railway geometry parameters measurement in this dissertation.Existing techniques and their problems for railway geometry parameters measurement are introduced. The feasibility and significance of using video metry for railway geometry parameters measurement are analyzed.The structure of the video metry system for railway geometry parameters measurement is designed. Its functions of each part are illuminated. Some hardware parameters of the video metry system are calculated according to the design index. Proper choicese are made for the hardwares with deeply investigated, including infrared artificial mark, video camera, narrow bandwidth light filter, motorized lens, industry computer, power supply and so on. Then the measure system is built.Two key techniques of this measure system are investigated: motorized lens autocontrol and sub-pixel location of the artificial mark. Two control schemes are brought up, and the one depending on image processing is applied. The capability of the six image definition functions is compared, and the one based on SOBEL differential is used in our lens control system. The sub-pixel location principle is introduced in detail, and digit image correlation sub-pixel location method is chosen for this measure system. The motorized lens autocontrol and artificial mark sub-pixel location are realized.When the measure system is ready, two experiments for moving object auto tracking based on motorized autocontrol and system precision are designed. Then error analysis is carried. Some of the key factors affecting the measure result are illuminated.The experiments' results indicate that the video metry system satisfies the needs of the railway geometry parameters measurement.