In the field of large-scale equipment manufacturing and precision assembly, the measurement reference field serves as the core foundation for achieving high-precision global coordinate unification. To enhance the accuracy and reliability of the joint adjustment solution during the construction of the reference field, a combined adjustment method integrating dual constraints of distance–scale factor with adaptive weighting is proposed. This method utilizes high-precision scale bars to provide absolute distance constraints, thereby determining the global spatial scale and mitigating scale divergence during coordinate estimation. Simultaneously, approximate coordinates of target points are employed as pseudo-observations for regularization, ensuring the full-rank solvability of the adjustment system. Upon this foundation, Helmert variance component estimation is adopted to dynamically adjust the weights of distance observations, pseudo-observations, and scale bar constraints according to iterative residuals. Comparative verification experiments were conducted utilizing a nose-cone model datum field and SA professional metrology software. The results demonstrate that the proposed algorithm achieves an average point precision of 0.021 mm, comparable to the 0.019 mm precision of the professional software. In regions with locally weak geometric strength, the maximum point error of the proposed algorithm is 0.029 mm, superior to the 0.173 mm of the control group, with the maximum deviation of datum artifact spatial length reconstruction being 0.015 mm. Enhancing geometric constraints and assigning adaptive weights to observations are effective ways to improve the accuracy of absolute coordinate solutions for the reference field.
Zhao et al. (Tue,) studied this question.