Acta Geodaetica et Cartographica Sinica ›› 2018, Vol. 47 ›› Issue (10): 1301-1306.doi: 10.11947/j.AGCS.2018.20170576

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On an Improved Iterative Reweighted Least Squares Algorithm in Robust Estimation

FANG Xing, HUANG Lixiong, ZENG Wenxian, WU Yun   

  1. School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China
  • Received:2017-10-11 Revised:2018-03-21 Online:2018-10-20 Published:2018-10-24
  • Supported by:
    The National Natural Science Foundation of China (Nos. 41774009;41474006;41674002;41404005)

Abstract: In geodesy,classical least squares (LS) estimation methods rely heavily on assumptions which are often not met in practice.In particular,it is often assumed that the data errors are zero mean distributed,at least appproximately.Unfortunately,when there are outliers in the data,the classical LS estimators frequently have meaningless performance.In this case,robust estimation such as M-type estimation is usually applied,which is numerically implemented by a so called iterative reweighted least squares algorithm.In the current reweighting process,however,the equivalent normal matrix is required to be inverted in every iteration,which needs an expensive computation demand,especially when the number of the unknown parameters is large.Therefore,in this contribution,the numerical process of the iterative reweighted least squares algorithm is essentially improved,which is mainly represented by avoiding the inversion of the equivalent normal matrix.The numerical example shows that the improved version is performed much superior to the previous one.

Key words: robust estimation, iterative reweighted least-squares, matrix inversion

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