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1.
黄加纳 《武汉测绘科技大学学报》1998,23(3):251-254
探讨了起算数据误差影响下的方差分量估计方法,给出了顾及起算数据误差影响时求解方差分量估值的方程组及单位权中误差估值的计算公式,并通过实例了说明了当起算数据误差较大时,它们对工分量估计的影响是不应忽略的。 相似文献
2.
针对起算数据具有误差时现有处理方法的缺陷,巧妙地利用了真值和估值之间的关系处理起算数据误差,提出了基于滤波的顾及起算数据误差的验后估计法,剔除了起算数据误差的影响,得出相对于起算数据误差基准的平差结果。平差计算与随机模型的验后估计同时进行,使数据处理得更加完善。 相似文献
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针对起算数据具有误差时现有处理方法的缺陷,巧妙地利用了真值和估值之间的关系处理起算数据误差,提出了基于滤波的顾及起算数据误差的验后估计法,剔除了起算数据误差的影响,得出相对于起算数据误差基准的平差结果,平差计算与随机模型的验后估计同时进行,使数据处理得更加完善。 相似文献
4.
针对Partial EIV模型的方差分量估计中未考虑参数估值偏差所带来的影响,将Partial EIV模型视为非线性函数得到参数估值的偏差及二阶近似协方差表达式,计算得到偏差改正后的参数估值,结合方差分量估计方法,更新由参数估值影响的矩阵变量,给出了基于偏差改正的方差分量估计迭代方法。试验结果表明,参数估值及其协方差主要受参数估值偏差大小的影响,加入偏差改正能够得到更加合理的参数估值及方差分量估值,偏差改正后的方差分量估值可更加合理地评估参数估值的精度信息。 相似文献
5.
在参数和起算数据的先验统计性质已知时,提出了基于滤波的顾及起算数据误差的赫尔默特估计法.这种方法估计出了相对于起算数据基准的精度,既充分考虑了起算数据的影响又没有增加计算量,并且将平差计算与随机模型的赫尔默特估计同时进行,使数据处理过程更加完善. 相似文献
6.
在参数和起算数据的先验统计性质已知时,提出了基于滤波的顾及起算数据误差的赫尔默特估计法。这种方法估计出了相对于起算数据基准的精度,既充分考虑了起算数据的影响又没有增加计算量,并且将平差计算与随机模型的赫尔估计同时进行,使数据处理过程更加完善。 相似文献
7.
基于移动开窗法协方差估计和方差分量估计的自适应滤波 总被引:8,自引:1,他引:8
基于移动窗口协方差估计和方差分量估计,提出了一种新的自适应Kalman滤波技术。计算结果证实,该方法能有效地控制观测异常和载体状态扰动异常对动态系统参数估值的影响。 相似文献
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Partial EIV模型的非负最小二乘方差分量估计 总被引:2,自引:2,他引:0
Partial Errors-in-Variables(Partial EIV)模型是EIV模型的扩展形式,权阵构造简单,当系数矩阵中存在非随机元素和随机元素时,Partial EIV模型的适用性更强。针对Partial EIV模型中随机模型不准确的情况,将系数矩阵和观测向量分别作为一类数据,本文在该模型的基础上,使用最小二乘方差分量估计方法,推导相关计算公式及迭代算法,分别估计出相应的方差分量估值。并对出现的负方差使用非负最小二乘理论,增加约束条件,对随机模型进行修正,得到更加合理的参数估值。试实验结果表明,本文的方法与其他方差分量估计方法等价。 相似文献
11.
顾及起始数据误差影响时单位权中误差的估值 总被引:1,自引:0,他引:1
黄加纳 《武汉大学学报(信息科学版)》1986,(4)
本文推导了在附有条件的间接平差和附有未知数的条件平差两种方法中,顾及起始数据误差影响时,计算单位权中误差估值(?)的公式,并以两个实例说明,平差时应该考虑起始数据误差对(?)的影响。 相似文献
12.
G. Fotopoulos 《Journal of Geodesy》2005,79(1-3):111-123
The well-known statistical tool of variance component estimation (VCE) is implemented in the combined least-squares (LS) adjustment of heterogeneous height data (ellipsoidal, orthometric and geoid), for the purpose of calibrating geoid error models. This general treatment of the stochastic model offers the flexibility of estimating more than one variance and/or covariance component to improve the covariance information. Specifically, the iterative minimum norm quadratic unbiased estimation (I-MINQUE) and the iterative almost unbiased estimation (I-AUE) schemes are implemented in case studies with observed height data from Switzerland and parts of Canada. The effect of correlation among measurements of the same height type and the role of the systematic effects and datum inconsistencies in the combined adjustment of ellipsoidal, geoid and orthometric heights on the estimated variance components are investigated in detail. Results give valuable insight into the usefulness of the VCE approach for calibrating geoid error models and the challenges encountered when implementing such a scheme in practice. In all cases, the estimated variance component corresponding to the geoid height data was less than or equal to 1, indicating an overall downscaling of the initial covariance (CV) matrix was necessary. It was also shown that overly optimistic CV matrices are obtained when diagonal-only cofactor matrices are implemented in the stochastic model for the observations. Finally, the divergence of the VCE solution and/or the computation of negative variance components provide insight into the selected parametric model effectiveness. 相似文献
13.
Robust estimation of geodetic datum transformation 总被引:18,自引:1,他引:17
Y. Yang 《Journal of Geodesy》1999,73(5):268-274
The robust estimation of geodetic datum transformation is discussed. The basic principle of robust estimation is introduced.
The error influence functions of the robust estimators, together with those of least-squares estimators, are given. Particular
attention is given to the robust initial estimates of the transformation parameters, which should have a high breakdown point
in order to provide reliable residuals for the following estimation. The median method is applied to solve for robust initial
estimates of transformation parameters since it has the highest breakdown point. A smooth weight function is then used to
improve the efficiency of the parameter estimates in successive iterative computations. A numerical example is given on a
datum transformation between a global positioning system network and the corresponding geodetic network in China. The results
show that when the coordinates are contaminated by outliers, the proposed method can still give reasonable results.
Received: 25 September 1997 / Accepted: 1 March 1999 相似文献
14.
悬索桥基准索股是主缆架设的重要部分,基准索股垂直度测量主要采用三角高程测量法,而大气垂直折光差是影响三角高程测量的主要误差源。本文以等影响原则为前提,对差分技术的原理进行分析,利用基准点已知信息,对三角高程测量中的大气垂直折光差进行修正,从而提高基准索股垂直度测量的精度。上述方法能够满足主缆架设精度要求,并且在实际应用中得到了较好的结果,可为类似桥梁工程提供指导。 相似文献
15.
陶本藻 《武汉大学学报(信息科学版)》2000,25(5):409-413
从残差的定量关系出发评述了检测粗差的数据探测法和抗差估计的选权迭代法 ,指出了其中用残差代替真误差所产生的问题及解决办法 ,并且导出了单位权方差估值、单位权中误差估值的概率分布 ,给出了后者的数字特征 ,对平差问题的精度体系作了统计分析。 相似文献
16.
钟差参数估计与预报是卫星导航系统应用中的一项关键技术。本文研究了基于哈达玛总方差的钟差参数预报方法。随机部分采用幂律谱模型,利用哈达玛总方差计算Kalman噪声参数,进而得到状态噪声和测量噪声协方差阵。最后利用IGS数据,验证了基于哈达玛总方差进行钟差参数估计与预报的适用性。结果表明,短期预报精度可达到亚纳秒级。 相似文献
17.
无缝仿射基准转换模型的方差分量估计 总被引:1,自引:1,他引:0
以无缝仿射基准变换为例,研究了无缝基准转换模型的方差分量估计理论,导出无缝基准变换过程中两套坐标的方差分量估计公式。通过模拟试验分析表明,采用方差分量估计方法能正确地恢复出客观体现两套坐标误差的方差值,从而有效提高无缝基准转换精度。 相似文献
18.
Khosro Moghtased-Azar Ramin Tehranchi Ali Reza Amiri-Simkooei 《Journal of Geodesy》2014,88(5):427-439
A typical problem of estimation principles of variance and covariance components is that they do not produce positive variances in general. This caveat is due, in particular, to a variety of reasons: (1) a badly chosen set of initial variance components, namely initial value problem (IVP), (2) low redundancy in functional model, (3) an improper stochastic model, and (4) data’s possibility of containing outliers. Accordingly, a lot of effort has been made in order to design non-negative estimates of variance components. However, the desires on non-negative and unbiased estimation can seldom be met simultaneously. Likewise, in order to search for a practical non-negative estimator, one has to give up the condition on unbiasedness, which implies that the estimator will be biased. On the other hand, unlike the variance components, the covariance components can be negative, so the methods for obtaining non-negative estimates of variance components are not applicable. This study presents an alternative method to non-negative estimation of variance components such that non-negativity of the variance components is automatically supported. The idea is based upon the use of the functions whose range is the set of all positive real numbers, namely positive-valued functions (PVFs), for unknown variance components in stochastic model instead of using variance components themselves. Using the PVF could eliminate the effect of IVP on the estimation process. This concept is reparameterized on the restricted maximum likelihood with no effect on the unbiasedness of the scheme. The numerical results show the successful estimation of non-negativity estimation of variance components (as positive values) as well as covariance components (as negative or positive values). 相似文献
19.
顾及系统误差的平差模型研究 总被引:9,自引:0,他引:9
在高精度测量中,利用平差模型从整体上对系统误差予以补偿和消除的理论研究已日益被关注,从国内外文献看,一般均着重于研究附加系统参数平差模型的理论和应用,考虑到系统误差源的复杂性,文中提出了附加系统权平差模型,附加系统参数和系统权平差模型。导出了平差公式和假设检验的统计量,附加系统参数模型是将系统误差影响归入函数模型,附加系统权模型是将系统误差影响归为随机模型,两者混合模型则是将系统误差影响分别归入函数模型和随机模型,这样就形成了顾及系统误差的平差模型体系。附加系统权平差模型涉及到系统方差估计这一难题,文中提出了按概率分布置信域的思想由最大误差估计系统方差的方法。 相似文献