Study On Accuracy Optimization Of Three-dimensional Coordinate Control Network

With the rapid development of large infrastructure equipment industry, geometric measurement of large equipment faces plenty of difficulties, such as large spatial dimensions, complex structures, relatively high measuring accuracy, poor measurement environment, etc. The traditional single-station measurement can’t balance the contradiction between range, accuracy and efficiency, is unable to adapt to the need of current measurement。Precision geometric measurement of large scale equipment must depend on constructing high accuracy three-dimensional coordinate control network to achieve the overall accuracy control. In this paper, theory of constructing high precision three-dimensional coordinate control network is presented to solve the problems of precision measurement for large scale equipment. Main research work contained in this paper is as follows:1、The problems of large scale equipment geometric measurement is analyzed, the defects of the traditional single-station measurement mode is discussed, application requirements, development trend and means of constructing control net is studied.2 、 Coordinate transformation and unification is key to realize the global measurement in large space. Coordinate transformation model and calculation method for transformation parameters are analyzed, rules of station-transfer error changing is studied, the method of reducing error of station-transfer is discussed.3、To optimize the angle error and improve the accuracy of global control points, trilateration control network is constructed by laser tracker with high accuracy interferometry ranging. Considering the ranging accuracy changed with distance, weighting of length is added to construct a weighted trilateration control network. Considering the unequal precision point observation, a trilateration control network with weighting and rank defect is constructed.4、By using a laser tracker’s high accuracy interferometry ranging property, length standard is constructed, then length standards are used as constraints to construct a multi-length constraint three-dimensional coordinate control network.5、The requirements of control network optimization software is analyzed, the overall frame of control network optimization software is designed, module of control network optimization software is implemented.