基于GPS/BDS组合的网络RTK列车定位方法研究

Research on Network RTK Train Positioning Method Based on GPS/BDS Combination

在低密度列车运行控制系统上,为尽可能精简轨旁设备,降低维护成本需求,卫星定位已成为铁路列车位置服务的重要支撑。载波相位差分(RTK)是卫星定位系统中用于提高定位精度和减少终端成本的主要方式。结合铁路线路的一维属性与长距离、高速率运行的特点,在常规RTK基础上,采用基于多基站网络的虚拟参考站(VRS)技术,以扩大系统定位服务范围和提高系统可靠性。通过统一GPS与BDS的时间和坐标系统,选择高度角联合信噪比随机模型,以及进行扩展卡尔曼滤波和整周模糊度快速固定,最终提供基于VRS的双星座网络RTK可靠定位结果。此外,还综合评估了在后处理模式下不同类型精密星历产品代替广播星历对定位精度的影响。

In the low density train operation control system,satellite positioning has become an important support for railway train location service in order to simplify the trackside equipment as much as possible and reduce the maintenance cost.Real Time Kinematic is the main method used in satellite positioning system to improve positioning accuracy and reduce terminal cost.Combined with the one-dimensional property of railway line and the characteristics of long distance and high speed operation,the virtual reference station technology based on the conventional RTK was adopted in this paper to expand the range of system positioning service and improve the reliability of the system.By unifying the time and coordinate system of GPS and BDS,selecting the height angle combined with the SNR stochastic model,and using the extended Kalman filter and the integer ambiguity fast fixing,the reliable positioning results of RTK for VRS-based double constellation network were finally provided.This paper also comprehensively evaluated the effects of different types of precision ephemeris products replacing broadcast ephemeris on the positioning accuracy in the post-processing mode.