GPS precise point positioning (PPP) is increasingly being used in many precise positioning applications to achieve sub-meter level accuracy using a stand-alone user receiver. To achieve the full-scale navigation parameters of position, velocity and attitude, GPS is often combined with the inertial navigation system (INS) to deliver navigation solutions in high update rate. However, GPS signals cannot always be tracked in difficult areas, which leads to an integration performance degradation because of INS sensor errors. Therefore, the authors propose a PPP-GPS/INS/odometer/map-matching integrated navigation system. The positioning performance based on the different International GNSS Service (IGS) products for train kinematic positioning applications is investigated. A field test was conducted on a specific low-density line to evaluate the proposed system. The test results confirm that the proposed multi-sensor navigation system can provide seamless navigation in both GPS available and unavailable situations with the accuracy of decimeter. Different IGS satellite orbits and clock offset products were used to generate the PPP results, and it was concluded that the IGS final products provide the best performance, with a distance root mean square (DRMS) of 0.138 m, and the IGS ultra-rapid product can also generate acceptable positioning solutions with a DRMS of 0.222 m.

中文翻译：

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基于PPP-GPS的分散式火车多传感器导航系统分析

GPS精确点定位（PPP）越来越多地用于许多精确定位应用中，以通过独立的用户接收器实现亚米级的精度。为了获得位置，速度和姿态的全方位导航参数，GPS通常与惯性导航系统（INS）结合使用，以高更新率提供导航解决方案。然而，GPS信号不能总是在困难的区域中被追踪，这由于INS传感器错误而导致集成性能下降。因此，作者提出了PPP-GPS / INS /里程表/地图匹配的集成导航系统。研究了基于不同国际GNSS服务（IGS）产品的列车运动定位应用的定位性能。在特定的低密度线路上进行了现场测试，以评估所建议的系统。测试结果证实，提出的多传感器导航系统可以在GPS可用和不可用的情况下以分米的精度提供无缝导航。使用不同的IGS卫星轨道和时钟偏移量产品产生PPP结果，得出的结论是，IGS最终产品提供了最佳性能，距离均方根（DRMS）为0.138 m，而IGS超快速产品还可以产生DRMS为0.222 m的可接受的定位解决方案。