海底大地基准点圆走航模式定位模型及分析

Positioning model and analysis of the sailing circle mode of seafloor geodetic datum points

圆走航模式是确定海底大地基准点位置的常用测量模式。本文对圆走航模式的定位效能进行了系统分析。首先分析了顾及声速剖面变化规律的声学测距非差定位模型和削弱系统误差影响的历元间差分定位模型,然后分析了圆走航模式下非差、单差定位模型的定位效能,包括位置参数的可估性,不同分量位置精度的最佳测量半径、所达到的理论精度,以及测距误差对定位参数的影响等。理论分析发现,在标准圆走航模式下,为确保基准位置不同分量精度应有不同的最佳测量半径,前后历元差分定位模型对高程分量不可估。模拟数据及实测算例均发现,圆走航模式下差分定位模型虽然削弱了测距系统误差的影响,但同时也降低了设计矩阵几何观测强度,甚至会造成观测模型病态化,导致差分模型深度信息估计精度明显削弱。

Sailing circle is a commonly used surveying pattern in determining the position of seafloor datum points.In this paper,the positioning efficiency of sailing circle mode is analyzed systematically.Firstly,the acoustic ranging non-differential positioning model considering the variation of sound velocity profile and the inter-epoch differential positioning model weakening the influence of systematic error are analyzed.Then,the positioning efficiency of non-differential and single-difference positioning models in sailing circle mode is analyzed,including the measurability of position parameters,the optimal measurement radius of different component position accuracy,the theoretical accuracy achieved,and the influence of ranging error on positioning parameters,et al.Theoretical analysis shows that in the standard sailing circle mode,to ensure the accuracy of different components of the datum position,different optimal measurement radiuses are derived,and the elevation component cannot be estimated with the pre epoch and post epoch differential positioning model.Both the simulation data and the measured examples show that the differential positioning model in sailing circle mode weakens the influence of the ranging system error,but also reduces the geometric observation intensity of the design matrix,which even lead to an ill-posed model and obvious weakening of the depth information estimation accuracy of the differential model.