This paper presents a novel estimation method for coarse alignment of a marine strapdown inertial navigation system (SINS) under mooring conditions. The properties of gravitational motion are used to improve the accuracy of coarse alignment. The parametric motion of gravitational apparent is a circle that is on the surface of a sphere. The location of this parametric circle is dependent on the definition of the reference frames and the initial angles of SINS. In the method proposed here the initial direct cosine matrix is calculated only from the location of the gravity motion parametric circle. The novelty of this paper is to provide a new method for estimating the gravity motion trajectory in inertial frame, as well as direct extraction of the initial direct cosine matrix from this estimated trajectory. Simulation and testing show that the proposed method is suitable for coarse alignment in mooring conditions.

中文翻译：

---

船用捷联惯导系统利用拟合参数重心运动位置的粗对准

本文提出了一种新的系泊条件下海上捷联惯性导航系统（SINS）粗对准估计方法。利用重力运动的特性来提高粗对准的精度。万有引力的参量运动是在球体表面上的一个圆。该参数圆的位置取决于参考系的定义和 SINS 的初始角度。在这里提出的方法中，初始正余弦矩阵仅根据重力运动参数圆的位置计算。本文的新颖之处在于提供了一种估计惯性系中重力运动轨迹的新方法，以及从该估计轨迹中直接提取初始正余弦矩阵。