Research On Recognizing And Extracting Measuring Information Of Complex Workpiece Based On New-generation GPS And MBD

Coordinate measuring technology is an important method to measure a complex workpiece. Recognition and extraction of geometrical surfaces and tolerances to be measured, which is based on 3D workpiece model integrating all of the measuring information, lays foundation for inspection planning and measuring implementation. Continuous development and improvement of new-generation Geometrical Product Specifications(GPS) standard, together with the proposal and application of Model-based Definition(MBD), provides a new research environment and realization way for measuring information extraction.To find a convenient and efficient method of obtaining coordinate measuring information, a tolerance-driven method was presented. Firstly, according to GPS and MBD, the 3D workpiece model was designed. Through analyzing the structural mode of geometrical surfaces and related tolerances, the structure of coordinate measuring information, which includes the coordinate system and model datum, tolerance and related geometrical features, and other workpiece information were given. Secondly, on the basis of tolerance-driven thinking, the recogniton and extraction mechanism of coordinate measuring information was proposed; With Topologically and Technologically Related Surfaces(TTRS) theory, workpiece measuring information representation model was constructed to represents the relationship between surfaces and related tolerances. Finally, respectively referring to the scope of new-generation GPS and the way dividing all geometrical features into seven invariance classes, the structure of Tolerance Set and detailed geometrical coordinate measuring information was given.In CATIA software, based on coordinate measuring information representation model and TTRS based topological geometrical definition of workpiece model surfaces, measuring information recogniton and extraction process was determined. At last, measuring information extraction tool was customized in CATIA software, and an example was given to verify the method and technology above.