中文摘要：

利用GPS定位全天候、高效率、低成本的特性,设计出一种新型的轨道外部几何参数测量系统。该系统由卫星系统、加载接收机的轨检仪、控制网和GPRS发射站组成。测量前,先构建边连式同步图形扩展式带状轨道监测控制网,并在现有的轨检仪上加载GPS接收机。测量过程中,轨检仪沿轨道运动：GPS控制网中4个GPS基站与轨检仪上GPS流动站实时采集定位信息;定位信息经双差处理和整周模糊度解算后,得到RTK（real-time kinematic）观测量,确立轨道中心线;结合轨检小车测出的轨道内部几何参数和轨道中心线,解算出轨道高程。静态实验与外场试验结果表明：该测量系统自动化程度较高,静态观测误差在0.5 mm以内,动态误差在15 mm以内,完全能够满足轨道外部几何参数高精度测量的要求。

英文摘要：

An external geometric parameter measuring system is designed using the GPS positioning technology. The traditional track inspection technology and GPS positioning technology are combined into the system. The system is composed of a four- componentsatellite system, track inspection apparatus carrying a receiver, control network and GPRS station. The track observation network is built at first while GPS base stations are already set up. At the same time, the GPS receiver is loaded on the existing track inspection instrument as a moving station. The data acquisition module of the measurement system consists of GPS base stations and a moving station. Then, real- time location information is collected by the GPS stations while the track inspection instrument walks along the track. The positioning data are processed by the double differencing carrier phase algorithm. The integer ambiguity resolution based on LAMBDA（ the least- squares ambiguity decorrelation adjust method） is the key problem of the GPS positioning. Next, the position of the antenna center is calculated. Finally, using internal geometric parameters and antenna center positioning data, the external railway geometric parameters are calculated. The results of the static experiment and field test confirm the validity of the measurement system. On the one hand, the static observation error is within 0.5 mm while the dynamic measurement error is less than 15 mm, on the other hand the labor cost of the system is low due to high automation.