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国内图书分类号:V412.4国际图书分类号:629.78工学硕士学位论文基于阻力参数估计的低轨卫星轨道确定与预报硕 士 研 究 生: 卢伟导师: 耿云海 教授申请学位级别: 工学硕士学 科 、 专 业: 飞行器设计所 在 单 位: 卫星技术研究所答 辩 日 期: 2008 年 6 月授予学位单位: 哈尔滨工业大学Classified Index: V412.4U.D.C.: 629.78Dissertation for the Master Degree in EngineeringORBIT DETERMINATION AND PREDICTION OF LOW EARTH ORBIT SATELLITES BASED ON ESTIMATING DRAG PARAMETERSCandidate:Supervisor:Academic Degree Applied for:Specialty:Affiliation:Date of Defence:Lu WeiProf. Geng YunhaiMaster of EngineeringSpacecraft DesignResearch Center of Satellite Technology June, 2008Degree-Conferring-Institution: Harbin Institute of Technology哈尔滨工业大学工学硕士学位论文摘要低轨卫星轨道动力学模型是其轨道确定和预报的根本,其中大气阻力模 型的不确定性导致很难较好的对低轨卫星进行轨道确定与预报。针对这一问 题,本文从大气阻力建模的问题出发,取得了以下研究成果: 首先,根据自由分子流学说,建立了大气阻力和大气升力的数学模型, 并对大气阻力模型中的不确定性因素进行了深入的分析。 然后,针对有效迎风面积的精确计算问题,引入微元划分的思想,提出 了微元中心距离准则方案、正方形微元准则方案和迎风面积包络微元法,并 分析了前两种方案的关键点和实现难点,对迎风面积包络微元法进行了详细的阐述,通过仿真计算得到,其计算精度可达 99.9%以上,从而有效地解决 了具有规则表面的卫星有效迎风面积的精确计算问题。接着,针对星载 GPS 接收机有测量数据的情况,研究了基于 EKF 的参数估计法的轨道确定方案,并通过仿真得到其定轨精度为 0.6m。并针对大 气密度的复杂性和有效迎风面积精确计算的计算量大而导致大气阻力的计算 复杂问题,提出了大气阻力等效模型方案,分析了作用在卫星上的大气阻力的变化规律,基于大气阻力的变化规律,建立了大气阻力的等效模型(由常值部分和周期变化部分构成)。在此基础之上,研究了基于 EKF 的等效阻力 参数估计法的轨道确定方案,通过仿真得到,其定轨精度为 0.8m,这种方 法比较适用于在轨实时计算。 基于以上的研究结果,提出了大气阻力模型的修正方案,并根据轨道确 定的结果,对大气阻力模型和大气阻力等效加速度模型进行了修正。在此基 础上,研究了利用修正后的大气阻力模型进行轨道预报的问题,通过仿真得 到,基于阻力系数估计法的轨道预报方案有着较好的预报精度,对卫星进行半天的轨道预报,其位置预报误差在 1.2km 以内。并分析了基于阻力等效 参数估计法预报精度较低的原因,对此提出了相应的提高轨道预报精度的解 决方案。最后,对基于阻力系数估计法和等效阻力参数估计法的轨道确定与 预报方案进行了详细的比较。关键词轨道确定与预报;大气阻力建模;迎风面积;阻力参数- I -哈尔滨工业大学工学硕士学位论文AbstractThe orbit dynamics model of Low-Earth-Orbit satellites is the basic of its orbit determination and prediction, in which the uncertainty of atmospheric drag model would bring on that its very hard to get exactly the better results of orbit determination and prediction for Low-Earth-Orbit satellites. This paper starts from the problem of modeling atmospheric drag against the above problems, and gets the great results as fellows: First of all, modeled the mathematical model of atmospheric drag and atmospheric lift on the basic of the theory of free molecular flow, and analyzed the uncertainty factors deeply to the atmospheric drag model. And then, aiming at the accurate calculation problem of effect windward area, the micro element division is introduced, proposed the schemes of micro- unit center distance criterion, the criterion of square micro-unit, and windward area envelope differential element method, and analyzed the key points and implementation difficulties of the first two schemes, then described the windward area envelope differential element method in detail, it gets the calculation accuracy of over 99.9% by simulation calculation, thus solved the accurate calculation problem of effective windward area of effectively for the satellite with regular shape.Furthermore, studied the theory of orbit determination of Low-Earth-Orbit satellites, based on that, aiming at the situation of GPS receiver onboard has measured data, studied the orbit determination schemes of drag coefficient estimation method and it gets the orbit determination accuracy of 0.6m through simulation. Then, aiming at the complex problem of atmospheric drag calculation which is caused by the complexity of atmospheric density and the calculation large of accurate calculation problem of effective windward area, proposed the scheme of atmospheric drag equivalent model, and modeled the atmospheric drag equivalent model (the atmospheric drag model based on the theory of free molecular flow) through analyzing the change law of atmospheric drag acted on a satellite. Based on that, studied equivalent drag parameters estimation method through EKF algorithm, the simulation result shows its orbit determination- II -哈尔滨工业大学工学硕士学位论文precision is at 0.8m, and this method is much better for calculation on-time on- orbit in engineering. Based on the results of the above, the scheme of corrected the atmospheric drag model was proposed, and corrected the atmospheric drag model according to the results of orbit determination. Based on that, aiming at the situation of GPS receiver onboard without measured data, studied the orbit prediction scheme based the corrected atmospheric drag model, through simulation, the resultsshows the orbit prediction scheme of drag coefficient estimation has better orbit prediction precision, its prediction error of position is within 1.2km for the half day of orbit prediction. And analyzed the reason of the bad prediction precision of equivalent drag parameters estimation scheme, then proposed the solution accordingly to improve the orbit prediction precision. Finally, the orbit determination and prediction schemes are compared between drag coefficient estimation method and equivalent drag parameters estimation method in detail.KeywordsOrbit Determination and Prediction;Modeling Atmospheric Drag;Windward Area;Drag Parameters- III-哈尔滨工业大学工学硕士学位论文目录摘要 .
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