Global Precision Control for Field Large-Scale Measurement Based on Uniformly Minimum Variance Unbiased Estimate

Global precision control is the basis of the field large-scale measurement (FLM). The main purpose is to improve the overall measurement performance by establishing the enhanced reference system (ERS). In this article, a novel global precision control method for the FLM based on the uniformly minimum variance unbiased estimate (UMVUE) is proposed. A universal calculation model of the measurement uncertainty is explicitly derived. By minimizing the integrated measurement uncertainty, the weight matrix for estimating the ERS points is defined based on the UMVUE. An iterative optimization algorithm is proposed to obtain the optimal UMVUE of the ERS points. The anisotropy and inhomogeneity of the measurement errors associated with the ERS points are fully considered and analyzed in the proposed method, by which the registration error of the ERS points is reduced and the global precision of the FLM is improved greatly. The simulation and practical experiments are conducted to verify the superiority of the proposed method. The experimental results show that the proposed method surpasses the traditional best fit of single station (BFSS) method and two state-of-the-art (SOTA) methods in global precision control. Meanwhile, the registration error determined based on the ground truth is reduced from 0.0302 to 0.0165 mm.