人造地球卫星有摄初轨计算的单位矢量法

本文根据单位矢量法测轨原理,给出了利用人造地球卫星测角资料测定有摄初轨的一种方法。其主要特点是: (1)既适用于测角资料,也适用于测距资料和测速资料,并适用于这些不同类型资料的各种组合; (2)适用于任意偏心率、任意轨道倾角的人造地球卫星; (3)有利于提高初轨测定精度,并改善整个计算过程的收敛性。 实际计算表明,只要具有适当的观测弧段,这种有摄初轨的单位矢量法是可靠的,有效的,可以推广应用。     

利用同步测距测速资料的卫星初轨计算新方法

本文给出了利用同步测距测速资料计算卫星初轨的一种新方法,其创新之处在于: (1)改进了初值选择方式。不仅适用于任意偏心率轨道;而且精度较高,从而可显著地改善迭代收敛过程。 (2)变换了条件方程的形式,使测距数据p和测速数据p分别独立地出现在方程右端,从而可方便地消减系统误差,并可进行加权处理,有效地提高初轨计算的定轨精度。实际计算表明,该方法是可靠的。     

超长弧段的无摄初轨计算方法

本文提出了一种适用于超长弧段(Δθ>90°或相邻两圈甚至更长)的无摄初轨计算方法,不仅可解决多数初轨计算中长弧段轨道计算的发散问题,而且在可以忽略摄动量级的条件下,能提高轨道半长轴的测定精度。经测距、测角资料的初步实际计算表明,该方法是可靠的,在工程任务中尚可进一步考验和完善。     

大偏心率卫星单圈短弧段观测的定轨精度分析

本文采用仿真计算的方法,对大偏心率(e≈0.7)卫星轨道近地点附近,短弧段观测的定轨精度进行了初步分析。给出了在有观测仪器误差、站址误差和测时误差条件下,定轨精度的最佳理论值。同时对如何提高定轨精度提出了几点建议。     

关于初轨计算

初轨计算通常是指在二体问题意义下的短弧定轨,为了适应测量精度的提高和深空探测(包括月球探测)轨道器所涉及力学模型的需要,给出一种在测角资料背景下,同时适用于无摄和受摄运动的初轨计算方法。而且,该方法不仅适用于椭圆轨道,亦适用于双曲线轨道,拓宽初轨计算的传统范畴。     

超长弧段的无摄初轨计算方法

本文提出了一种适用于超长弧段(Δθ>90°或相邻两圈甚至更长)的无摄初轨计算方法，不仅可解决多数初轨计算中长弧段轨道计算的发散问题，而且在可以忽略摄动量级的条件下，能提高轨道半长轴的测定精度。经测距、测角资料的初步实际计算表明，该方法是可靠的，在工程任务中尚可进一步考验和完善。     

以点位观测为主的任意偏心率卫星初轨计算方法

本文给出了以点位观测为主的单站初始轨道计算方法。为了适用于任意偏心率卫星,作者对初值选择进行了有效的改进;为了提高初轨计算的定轨精度,进一步扩大收敛范围,作者针对方位角A、高度h、斜距ρ和斜距变化率ρ具有不同精度的实际,提出了加权处理的具体措施。实际计算表明,方法是可靠的。     

轨道机动模型在低轨航天器定轨中的应用研究

现代航天任务中,各类航天器由于工作的需要必须进行适时的变轨或进行其它轨道机动.由于这些轨道机动的动作导致前后数据不能有效的拟合,降低了定轨精度.为此,建立了适用于各类航天器轨道机动的动力学模型,通过运用测轨数据使用数值积分方法求解各类模型参数,着重探讨近地航天器的轨道机动的影响,并主要使用GPS导航定位数据分析其精度,实现了轨控参数的求解标定,同时提高了短弧段的定轨能力和预报精度.     

天体轨道测定的一种非线性方法

本文提出了天体轨道测定的一种非线性方法——单位矢量法。其主要特点是: (1)既适用于初轨计算,也适用于轨道改进; (2)既适用于任意偏心率轨道的天体,也适用于任意类型的观测数据; (3)在轨道改进中,对六个轨道根数的测定,利用非线性处理代替常规的线性处理,避免了有时必须寻求的复杂的有摄偏微商的计算,既有利于改善迭代收敛过程,还可提高轨道精密测定的计算速度。 初步实践和理论分析表明,该方法是可靠的,具有推广应用价值和发展潜力。     

嫦娥二号再拓展试验测定轨精度研究

基于＂嫦娥二号＂卫星再拓展试验的设计轨道,研究各种摄动力对轨道确定精度的影响,得出的结论是：若要达到km量级的轨道确定精度,必须考虑除天王星和海王星之外所有大行星以及日月的质点引力。文章进一步利用数值分析法研究再拓展任务的轨道确定精度,分析结果表明：基于目前的测控条件,使用30 d以上的测轨弧段可以得到稳定可靠的轨道解,而短弧（小于20 d）稳定轨道的获取需要VLBI（甚长基线干涉）测轨数据支持;当＂嫦娥二号＂距离地球700万km时,测控精度可优于30 km;虽然每天测轨弧段的增加可以改善轨道精度,但是当增加到8 h以上时,定轨精度将不再有明显改善。     

基于粒子群算法的极短弧定轨

针对经典的初轨计算方法在极短弧定轨中不适用的情况,建立了一种基于粒子群算法的极短弧(TooShort-Arc,TSA)定轨的计算方法。该方法将问题转化为两个三变量的分层优化问题,采用(a,e,M)作为优选变量,在保持问题维数较低的同时,实现了计算结果和观测资料的解耦。由于实测资料处理中的野值剔除方法不适用于粒子群算法,所以,采用稳健估计法,通过在适值函数中使用最小中值二乘准则,实现了稳健的极短弧计算方法。同时,应用MATLAB计算软件,选用缺省参数实现该算法,以进行数据验证。基于实测数据的数值验证表明,方法对于近圆轨道目标30s以下的弧段仍可以获得有效的结果,10s弧段误差仅为16km。此精度满足后续处理的需要,且方法稳健,具有很高的崩溃点。     

一种大椭圆轨道卫星星历预报方法

针对大偏心率轨道长时间星历预报,稠密输出星历的低效率问题,提出了一种新的星历预报方法。该方法通过建立卫星摄动力模型,对卫星运动方程进行数值积分来获取卫星星历。该方法的轨道积分器以标准的8阶Adams-Cowell多步法为基础,针对大偏心率轨道的特性,在一个轨道周期的不同时段内采用不同的积分步长,同时引入了用于生成小间隔等间距卫星星历的插值公式。该方法降低了卫星运动方程右函数的计算次数,尤其适用于需要稠密输出卫星星历的情况。以STK(Satellite Tool Kit,卫星工具包)的HPOP(High Precision Orbit Propagator,高精度轨道预报)模型为验证基准,通过数学仿真校验了该方法的有效性和精度。算例表明,该方法在预报精度损失很小的情况下,计算时间远小于标准的多步法和HPOP模型。     

基于连续同伦算法的天基仅测角初定轨方法

要进一步提高天基短弧初定轨的精度,在观测资料精度较高的情况下,仅考虑二体问题是不够的,还应考虑轨道摄动的影响。因此,基于无摄初轨的单位矢量法原理和矢量斜分解方法,给出了考虑摄动的天基仅测角初定轨单位矢量法。针对天基仅测角观测条件方程组求解过程中易出现迭代不收敛或收敛到平凡解的问题,引入连续同伦算法求解观测条件方程组,提出了单星观测方式下的空间目标天基仅测角初定轨方法,并通过数值仿真算例验证了该算法在较大范围的收敛性和数值稳定性。     

高重合度齿轮传动系统的振动参数稳定性

研究了高重合度齿轮转子-滚动轴承传动系统的振动强度稳定性以及振动轨道稳定性随系统参数的变化规律。通过振动强度参数稳定域的计算,量化了高重合度齿轮副对齿轮转子 滚动轴承传动系统稳定性提升的贡献大小。结果发现在转子质量偏心较小的条件下,高重合度齿轮系统的振动强度稳定性要比普通重合度齿轮系统提升很多；但在转子质量偏心较大时,高重合度齿轮副的采用对传动系统参数稳定域的扩张并没有显著贡献。通过振动轨道稳定性全局分岔图的计算,明确了滚动轴承游隙、转子质量偏心等参数对高重合度齿轮转子-滚动轴承系统振动轨道稳定性的影响规律,获得了系统各种稳定周期轨道及非周期轨道与对应参数区间的映射关系。      

低轨卫星对高轨卫星仅测角初轨计算方法

针对我国地面测站对高轨卫星监视能力缺乏的问题,提出一种低轨卫星对高轨卫星仅测角初轨计算方法。该算法引入天基跟踪坐标系,消除测距信息影响,建立仅测角观测方程;引入法向运动,增加摄动因素影响,建立扩展拉普拉斯动力学模型;推导分析观测模型和动力学模型的关系方程,将初轨计算问题转换为非线性方程求解问题,利用高斯全主元消去法完成方程求解。通过实战和仿真测角数据对方法进行检验,结果表明,该方法能利用仅测角数据对非合作目标进行初轨确定,精度在公里量级,可为我国地基监视系统提供补充参考。     

Determination des orbites des satellites artificiels

Summary The problem of the determination of the orbit of a celestial body is an old astronomical problem, of which solutions can be found in many classical books on elementary celestial mechanics. However, the introduction of new (radioelectric) means of observations for the artificial satellites have brought up new solutions of this old problem.The author reminds the definitions of the six elliptic elements of an orbit. The problem of their determination is usually divided into two separate steps: a preliminary orbit determination and the improvement of the preliminary elements. Two principal types of preliminary orbit determination exist: the Gaussian type, purely geometrical in which the positions of the body at two different times are determined, and the Laplacian type, of a more dynamical character, in which both position and velocity vectors are found for a given time. The improvement of the preliminary elements is usually obtained by a numerical solution of equations of variations of the elements, minimizing the sum of the squares of the angular distances between the computed and the observed points. The elements on which these variations are applied can be quite various. The coefficients of the equations are usually obtained numerically, although their analytical expressions can also be derived.Most of the modification proposed to the classical methods of orbit determination are more technical improvements in connection with the computation on electronic machines. The most interesting modifications are inspired by the fact that time measurements are less precise than the position (Batrakov, Iszak), the effects of this difference in errors are discussed in this paper. In some cases, using Laplace's method, no preliminary orbit is computed, and all the observations can be used at once (Barlier, Kovalevsky).The determination of orbits from radar measurements is discussed. The proposed methods are quite different in principle from the classical ones. They are actually improvements of a circular orbit whose determination is made by a method of undetermined coefficients (Baker). Some of the elements determined by these methods are quite unstable, and it is always wiser to use other informations together with radar measurements.The determination of orbits from Doppler data alone has been worked out by many investigators. It is the inverse problem of the main problem of all navigational systems. The method proposed by Patton is summarized. The principles of others are quite analogous. The results are improved when more than one receiver are used. The different types of corrections: refraction, perturbations, etc., should be introduced in later stages of the determination, and the whole frequency curve is to be used if a good determination of all elements is desired.Finally, the author quotes a method (Baker) using both Doppler and radar data, and the solution of a new problem: the determination of the orbit of a satellite of another planet from Doppler data alone (Deutsch).     

Aiming at a 1-cm Orbit for Low Earth Orbiters: Reduced-Dynamic and Kinematic Precise Orbit Determination

The computation of high-accuracy orbits is a prerequisite for the success of Low Earth Orbiter (LEO) missions such as CHAMP, GRACE and GOCE. The mission objectives of these satellites cannot be reached without computing orbits with an accuracy at the few cm level. Such a level of accuracy might be achieved with the techniques of reduced-dynamic and kinematic precise orbit determination (POD) assuming continuous Satellite-to-Satellite Tracking (SST) by the Global Positioning System (GPS). Both techniques have reached a high level of maturity and have been successfully applied to missions in the past, for example to TOPEX/POSEIDON (T/P), leading to (sub-)decimeter orbit accuracy. New LEO gravity missions are (to be) equipped with advanced GPS receivers promising to provide very high quality SST observations thereby opening the possibility for computing cm-level accuracy orbits. The computation of orbits at this accuracy level does not only require high-quality GPS receivers, but also advanced and demanding observation preprocessing and correction algorithms. Moreover, sophisticated parameter estimation schemes need to be adapted and extended to allow the computation of such orbits. Finally, reliable methods need to be employed for assessing the orbit quality and providing feedback to the different processing steps in the orbit computation process. This revised version was published online in August 2006 with corrections to the Cover Date.     

无线电掩星技术在大气探测的应用

通过介绍GPS在大气探测中的应用,引入了一种新的研究大气模型的方法——无线电掩星技术。阐明了无线电掩星技术的发展历程、反演原理及应用前景,并结合我国航天实际,提出了一种利用北斗导航系统进行大气参数反演,修正航天器轨道测量数据,从而提高定轨精度的新思路。     

I: PRECISE ORBIT DETERMINATION AND GRAVITY FIELD MODELLING: Strategies for Precise Orbit Determination of Low Earth Orbiters Using the GPS

Considerable experience accumulated during the past decade in strategies for processing GPS data from ground-based geodetic receivers. First experience on the use of GPS observations from spaceborne receivers for orbit determination of satellites on low altitude orbits was gained with the launch of TOPEX/POSEIDON ten years ago. The launch of the CHAMP satellite in July 2000 stimulated a number of activities worldwide on improving the strategies and algorithms for orbit determination for Low Earth Orbiters (LEOs) using the GPS. Similar strategies as for ground-based receivers are applied to data from spaceborne GPS receivers to determine high precision orbits. Zero- and double-differencing techniques are applied to obtain kinematic and/or reduced-dynamic orbits with an accuracy which is today at the decimeter level. Further developments in modeling and processing strategies will continuously improve the quality of GPS-derived LEO orbits in the near future. A significant improvement can be expected from fixing double-difference phase ambiguities to integer numbers. Particular studies focus on the impact of a combined processing of LEO and GPS orbits on the quality of orbits and the reference frame realization. This revised version was published online in August 2006 with corrections to the Cover Date.