Abstract: Laser tracker as a three-dimensional measuring instrument is widely used in industrial measurement. It can rapidly and accurately detect the geometric error of numerical control machine tool on the basis of multi-station and time-sharing measurement principle. The machine tool is controlled to move on the preset path in the 3D space, and a laser tracker is used to measure the same motion trajectory of the machine tool at different base stations. Based on global positioning system(GPS) principle, the relative location of base station and the space coordinates of measuring points are determined, and then the geometric errors of machine tool are identified. By establishing the mathematical model of multi-station and time-sharing measurement, the algorithm of multi-station and time-sharing measurement is given, and the error separation algorithm is deduced and proved feasible by simulation. Results of experiment show that a laser tracker completes the precision detection of a numerical control milling machine within 4 hours on the basis of multi-station and time-sharing measurement principle, and errors of numerical control milling machine are separated. This method has high efficiency and high precision, so it has certain applications in precision detection of medium-high level numerical control machine tools.

Key words: Error separation, Geometric error, Laser tracker, Multi-station and time-sharing measurement