GNSS应急辅助定位及精度评估方法研究

在可视卫星数少于4颗、无法进行传统导航解算的恶劣环境下，导航接收机可利用外部高程气压计提供的高程或者内部守时模块的钟差等信息进行应急辅助定位。在该应急辅助定位工作模式的误差分析中，传统导航定位误差传递模型无法适用。针对此问题，本文在研究三星结合高程、三星结合钟差、双星结合高程钟差等几种应急辅助定位原理的基础上，给出了新的应急辅助定位误差传递的分析模型，利用仿真算例验证了该模型的正确性。最后通过对定位精度的分析，说明根据卫星分布特点可以按照本文方法量化得到伪距测量与辅助信息的精度的最优数量级关系，可以用最小代价实现定位精度的提升。该结论可指导接收机外部辅助器件的选择。

GNSS emergency positioning method and research on the accuracy estimation

Abstract: Under the harsh environment in which the number of visual satellite is fewer than four and traditional navigation solution cannot be completed, navigation receiver could enter the emergency auxiliary positioning mode by equipping the user with external elevation barometer providing for elevation information, or with internal punctuality module providing for clock bias. The traditional navigation and positioning error propagation model cannot be applied to analyze the error in this emergency assisted positioning mode. To solve this problem, this paper focus on the basis of several emergency auxiliary positioning principles, such as three satellites combined with the elevation, three satellites combined with clock bias, two satellites combined with elevation and clock bias, and gives a new error propagation analysis model of emergency auxiliary positioning, verifying the correctness of the model by simulation example. Finally, through the positioning accuracy analysis, concluding that the present method could quantify the optimal magnitude relations between pseudorange measurements and the accuracy of the auxiliary information in accordance with the satellite distribution characteristics, whose positioning accuracy improvement can be realized with minimum cost. This conclusion can guide the choice of external auxiliary devices for navigation receiver.