基于观测数据拟合的天文自主定位算法

摘要

According to maritime astronomy positioning principle,the special nature of the sun can be used for astronomical positioning.When the sun transits,the green semicircle angle is equal to observer’s longitude. According to the law of the sun’s apparent motion,when one uses a sextant,it is difficult to determine the tran-sit time of the sun,and the longitude error will be introduced.In order to solve this problem,combined with da-ta fitting techniques,first the feasibility of fitting solar altitude curve is discussed and demonstrated,then a ce-lestial autonomous positioning method is proposed that doesn’t need projected position.Experimental results showed that the positioning cycle with the algorithm is short,it is simple to carry out and helps to reduce acci-dental errors.Under skilled observation level,maximum error of latitude and longitude are 0.8 and 2.5,which can fully meet the needs of the general maritime activities.%根据海上天文定位原理，太阳上中天时的格林半圆时角等于测者所在位置的经度，但六分仪观测难以确定太阳上中天的较准确时间，由此产生的经度误差往往过大，不能满足航海需求。采用数据拟合技术对太阳高度曲线进行拟合处理，能够比较准确地求出太阳上中天的时间，从而给出了不需要推算船位的天文定位算法。通过海上大量实验结果表明：该算法定位周期短、简便易行且有利于减小偶然误差。采用现有六分仪进行观测，定位的纬度最大误差为0．8，经度最大误差为2．5，满足海上航行的导航精度要求。