The Research On Key Technology And Application Of Uncertainty Evaluation Based On GPS

With the development and application of CAD/CAM/CAQ, and the application of the new techniques, the new technologies and new materials, machining accuracy increases from micron to nanometer. The GPS system has improved from the first generation depended on geometry to the second generation which relies on metrology. The new generation GPS system takes the extended uncertainty as a link, integrates product function, specification and verification, to realize optimal configuration of its resources. Then, the uncertainty evaluation is the basis and key of the new generation GPS application in engineering. The problem of evaluation uncertainty becomes the bottle-neck when the new generation GPS application in engineering practices.The key technology of uncertainty evaluation and application was studied thoroughly in this thesis. The main contents are as follows:The digital surface model, the acquisition tools of geometrical elements-operation and operator, the extended uncertainty of the new generation GPS and its application technology, uncertainty evaluation methods and its applications, management of measurement uncertainty for the PUMA program based on GUM, are described using the technology of the new generation of GPS. The application rules are analyzed, and the relationships between them are derived.To solve the problem of estimate uncertainty for small samples in engineering, the gray system theory of measurement uncertainty evaluation is introduced, a gray measurement model of uncertainty and the calculated method of standard uncertainty are given. For the demerit of GUM method in measurement uncertainty, the Monte-Carlo method applied to the assessment of uncertainty in GPS is presented, the measurement uncertainty process of uncertainty evaluation based on GPS is given. The results of experimentation show that:the uncertainty evaluation used Monte Carlo method was closed to that of GUM calculation method and the Monte-Carlo method overcome the defects and deficiencies using traditional GUM method.To solve the problem of the uncertainty evaluation of geometric errors, the model of geometric error measurement and assessment of uncertainty are analyzed. In practice, if the operators we used all adopt from norms, then there is no method uncertainty, the measurement uncertainty is the result of implementation uncertainty passed from operators. Based on this conclusion, the source and composition of the implementation uncertainty are analyzed, its propagation in operators, including filter and fitting, are researched, and the formulas for calculating measurement uncertainty are derived. Take the cylindrical error as an example, the formulas of the measurement of cylindrical Uncertainty using a cylindrical measuring instrument are derived, and the practical foundation of integration between uncertainty and the geometric error digital measurement system are researched.To further improve the geometric error digital measurement system function, the uncertainty evaluation function is integrated into the system. The system will promote the new generation GPS in the application of practical engineering.