卫星自主导航中25～60公里星光大气折射模型研究

Study on Model of Starlight Atmosphere Refraction from 25 km to 60 km in Autonomous Navigation for Satellite

星光大气折射法是卫星自主导航技术发展起来的一种新的导航方法,直接影响其精度的主要因素是星光大气折射模型的不确定性.本文在研究卫星自主导航方法和大气折射原理及平流层大气的实际状态和基本变化规律的基础上,基于地球大气密度的实验数据,给出了平流层大气密度随高度变化的模型.采用球形大气分层的研究方法,根据光在湍流大气中的传播机理和卫星、地球、星光切线高度之间的几何关系以及光学定律推导出的折射角与大气密度的关系式,建立了星光大气折射模型,给出了影响导航精度的高度范围25～60公里的星光大气折射角随切线高度变化的经验公式.仿真结果表明,符合大气折射的变化规律,与现有的经验公式吻合较好,而且考虑了大气密度实际变化的影响,并有较大的实际应用价值.

The method of starlight atmosphere refraction is a new kind of navigation method developed based on autonomous navigation for satellite, the main direct factors of affecting it's precision are uncertainty of model of starlight atmosphere refraction. In the paper, the varying model of atmosphere density with height is given by researches on method of autonomous navigation for satellite, actual state and basic change rule of atmosphere in calm fluxion layer, based on the experiment data of atmosphere density. Further more, a model of starlight atmosphere refraction is set up, a experience formula is given of refraction angle varying with tangent height within range of height 25~60km, adopting spherical delaminating method, based on mechanism of light spread in onflow atmosphere, geometrical position among satellite, the earth, starlight tangent altitude and a relation formula between refraction angle and atmosphere density which is derived out by optics law. The simulation results show that the formulas proposed in the article accord with the change rules of atmosphere refraction, fit with the existing experience formulas, moreover take into account the influence of real varying of atmosphere density and with considerable practicality.