共查询到17条相似文献,搜索用时 62 毫秒
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LP估计在星载GPS运动学定轨中的应用及精度分析 总被引:2,自引:0,他引:2
为得到高精度的星载GPS运动学定轨,必须利用观测精度高的相位观测值,但是相位观测值预处理后,仍然存在残余小周跳.在残差服从正态分布情况下LS法是最佳参数解算方法,但该方法不能解决资料的系统误差消除问题,LP估计是处理资料残差分布含有系统误差的有效方法之一.基于LS、LP方法的有效条件和GPS数据预处理的特性,将LP估计方法引入星载GPS运动学定轨数据处理中,以CHAMP卫星资料为例,研究了LP估计在星载GPS运动学定轨中的应用及其精度分析.实践表明:在处理含有残余小周跳的相位观测值时,LP估计比LS更有效,提高了星载GPS运动学定轨精度,但随着残余周跳的进一步修复,LP估计相对于LS估计的优越性越来越弱,在资料完全没有系统误差,残差服从正态分布的情况下,LP估计不能很好地体现其优越性,精度反而低于LS估计. 相似文献
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当测轨数据误差不服从正态分布时,传统的最小二乘(LSE)轨道确定方法将不是最优的.为了获得高精度的定轨结果,一种可行的策略是采用基于最小p范数(Lp)的轨道确定方法.通过分析Lp估计的相关性质,得出普通Lp估计不具有良好的抗差性的结论.为抑制模型误差和异常值的影响,提出了基于数据深度加权的稳健最小p范数估计方法,并证明了相关性质,得出了其崩溃点可以达到1/2的结论.最后,通过残差分析和矩估计法自适应估计相关参数,使得估计达到最大效率.以天基空间目标监视系统为背景进行了仿真试验.结果表明,当观测数据存在系统误差或异常值时,或者当目标动力学模型存在误差或者天基观测平台存在系统误差时,即使观测数据服从正态分布,LSE也不是最优的,在这种意义下自适应稳健Lp估计轨道确定方法比传统轨道确定方法更加稳健,定轨精度也更高. 相似文献
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论述的短弧定轨,是指在无先验信息情况下又避开多变元迭代的初轨计算方法,它需要相应的动力学问题有一能反映短弧内达到一定精度的近似分析解.探测器进入月球引力作用范围后接近月球时可以处理成相对月球的受摄二体问题,而在地球附近,则可处理成相对地球的受摄二体问题,但在整个过渡段的力模型只能处理成一个受摄的限制性三体问题.而限制性三体问题无分析解,即使在月球引力作用范围外,对于大推力脉冲式的过渡方式,相对地球的变化椭圆轨道的偏心率很大(超过Laplace极限),在考虑月球引力摄动时亦无法构造摄动分析解.就此问题,考虑在地球非球形引力(只包含J2项)和月球引力共同作用下,构造了探测器飞抵月球过渡轨道段的时间幂级数解,在此基础上给出一种受摄二体问题意义下的初轨计算方法,经数值验证,定轨方法有效,可供地面测控系统参考. 相似文献
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单位矢量法的数学模型(MMUVM)及其简化形式(PUVM1)的迭代法的收敛性 总被引:1,自引:0,他引:1
利用人造地球卫星观测资料测定有摄初轨的单位矢量法(PUVM1),已得到了非常广泛地实际应用.为了对单位矢量法作进一步地完善和改进,首先在考虑测量误差模型的基础上,建立单位矢量法所对应的数学模型MMUVM.它本质上就是一个非线性最优化问题.针对MMUVM,先分别使用多圈仿真数据和实测数据,形成了与之相对应的目标函数,再利用求解最优化问题的一种三对角二次插值模型的直接搜索方法,分别对其进行了数值处理.计算结果表明,所建立的优化模型MMUVM正确合理,所采用的直接搜索方法实用有效.其次,进一步指明了PUVM1和MMUVM之间关系,即:从本质上讲,PUVM1就是MMUVM的一种简化形式.从数学原理上,清楚地解释了利用PUVM1的准法化方程,只能使用单圈短弧段数据进行初始轨道确定,而不能使用长弧段多圈资料进行轨道确定或轨道改进的根本原因.最后,对PUVM1的迭代算法的收敛性问题进行了初步的理论分析,并给出了相应的数值验证实例,指出了PUVM1的迭代格式是条件收敛的,即:只有在满足一定条件后,才能收敛.这也就意味着:有的时候,尽管准法化方程是合情合理的,但是,此时该迭代法却是发散的,无法迭代求出所要的解. 相似文献
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利用全球卫星激光测距服务系统(ILRS,International Laser Ranging Service)标准点资料对Ajisai卫星进行精密定轨,残差均方根(RMS)优于3 cm,得到该星的精密轨道.进而对长春站40 cm空间碎片光电望远镜获得的Ajisai卫星的天文定位资料进行精度分析,外符合精度约3″左右.单独利用天文定位数据进行轨道改进,内符合精度优于3″.改进轨道的x、y、z坐标3分量在观测数据覆盖范围内的精度在100 m之内.同样地对Jason-1卫星作数据分析,结果和Ajisai卫星精度相当.分析各个弧段的精度变化,发现定标星个数减少,会导致天文定位精度下降.据此提出可以把最少定标星比例作为评定数据质量的参考指标之一. 相似文献
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碰撞风险评估标准适用性分析 总被引:1,自引:0,他引:1
随着空间碎片数量的不断增加,空间目标碰撞预警技术已经受到人们越来越多的关注.早期普遍使用几何区域(BOX)判定法对空间目标的碰撞风险进行评估,但它是一种比较保守的方法,工程实用性低;90年代后开始广泛地研究和采用碰撞概率判定法,这种方法综合考虑空间目标交会时刻的多个参数,但是由于其数学模型对轨道误差数据的依赖程度很高,所以在某些情况下会导致预警结果不准确.通过仿真的方法,模拟两条确定交会的标准精密轨道,由程序生成随机误差加入到标准轨道生成有误差的轨道,计算最接近距离和碰撞概率,并分析二者之间的关系.结果表明,当轨道预报精度较差时,碰撞概率判定法可能会失效,需要结合几何区域判定法进行综合判定,以避免碰撞预警过程中的"误判"和"漏判". 相似文献
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基于单站短弧段光学观测的低轨卫星轨道预报算法 总被引:1,自引:0,他引:1
基于单站短弧段的目标跟踪预报技术是保证高精度光电经纬仪在非常规环境下正常跟踪捕获目标的重要途径.构建了基于非线性滤波器的跟踪预报算法,能够在正常情况下为闭环跟踪提供引导数据,同时构建了基于非线性变换的目标预报算法,可以在无有效观测数据情况下为经纬仪提供轨迹引导,保证目标不丢失.证明了非线性滤波在单站短弧段跟踪预报算法中比常规扩展卡尔曼滤波(Extended Kalman Filter,EKF)更有效.计算表明,本文设计的非线性滤波器可以作为光学跟踪设备的引导算法,引导精度同经纬仪的随机测量精度等量级,在设备系统误差达到50"时,预报60 s的精度可达到20",仍然满足跟踪设备的视场要求. 相似文献
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In this paper we investigate the influence of a varying gravitation constant on the orbits of celestial bodies. Regarding the eccentric anomaly as an independent variable, we find the solutions to the perturbed equations of motion. In the first order solutions, we find the secular and periodic variations in semi-major axis. For the other orbital elements only periodic variations exhibit. However in the second order solutions, the longitude of periastron and the mean longitude have secular terms. Applying the calculations to six selected binaries, we give the numerical estimations of the variations of orbits. These results are then carefully compared and discussed. 相似文献
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In the light of the problem of amalgamation and processing of multisource observational data in the combined orbit determination of near-earth satellites of the bi-satellite positioning system, the optimal weighting method of the improved variance component estimation of the two-step systematic error correction of homogeneous observational data is proposed. Analyses show that the multi-source amalgamation measurement model of the heterogeneous observational data essentially is a multi-structure, multi-parameter non-linear regression model, and the optimal weighting method of the combination of model structure characteristic analysis and variance component estimation of the heterogeneous observational data is established. The realization algorithms of the optimal weighting and the combined orbit determination parameter estimation of the two sorts of observational data are designed, and the simulation experiments of the combined orbit determination are carried out by taking the distances among the two satellites and the backup satellite and the homogeneous observational data and the distance between the two satellites and the heterogeneous observational data of satellite sensor angle measurements as the examples. The results of theoretical analysis and simulation calculation show that for the combined orbit determination of homogeneous observational data, the accuracy of orbit determination obtained by adopting the variance component estimation method of the two-step systematic error correction can be more superior than that obtained by means of the traditional empirical weighting method. For the combined orbit determination of heterogeneous observational data, through the introduction of the weighting factor by which the model structure is characterized the accuracies of the combined orbit determination of the near-earth satellite and geostationary satellite are both improved to a certain extent in comparison with the mean weighting mode. 相似文献
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It is an objective fact that there exists error in the satellite dynamic model and it will be transferred to satellite orbit determination algorithm, forming a part of the connotative model error. Mixed with the systematic error and random error of the measurements, they form the unitive model error and badly restrict the precision of the orbit determination. We deduce in detail the equations of orbit improvement for a system with dynamic model error, construct the parametric model for the explicit part of the model and nonparametric model for the error that can not be explicitly described. We also construct the partially linear orbit determination model, estimate and fit the model error using a two-stage estimation and a kernel function estimation, and finally make the corresponding compensation in the orbit determination. Beginning from the data depth theory, a data depth weight kernel estimator for model error is proposed for the sake of promoting the steadiness of model error estimation. Simulation experiments of SBSS are performed. The results show clearly that the model error is one of the most important effects that will influence the precision of the orbit determination. The kernel function method can effectively estimate the model error, with the window width as a major restrict parameter. A data depth-weight-kernel estimation, however, can improve largely the robustness of the kernel function and therefore improve the precision of orbit determination. 相似文献
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