Study On The Evaluation Of Orientation Error Based On New GPS

The orientation error is an important indication of the position precision of parts. The evaluation method precision has a significant influence on product quality and performance. With the progress of modern industry, coordinate measuring techniques becomes a new technology of measurement.The researeh based on the orientation error evaluation method has more practical value.Currently, the common orientation error evaluation method isn’t compatible with the new generation Geometrical Product Specification (GPS), and the evaluation results often ignore the influence of uncertainty. According to the current situation, based on the new GPS system and uncertainty theory, the orientation error evaluation method and its uncertainty computation method are researched. The main contents are as follows:Firstly, the orientation error evaluation mathematical model is developed. Based on the minimum zone method which satisfies the minimum principle, the datum line and plane is built. Then by using of coordinate rotation method, the new coordinates the datum elements of which are line and plane respectively are developed. According to the definition of orientation tolerance and the model of tolerance zone, the orientation error evaluation model is proposed, and the derivative process of evaluation is detailed.Secondly, the Particle Swarm Optimization (PSO) algorithm is introduced for orientation error evaluation. The essence of orientation error evaluation is to solve multi-dimension nonlinear optimization problem. Owing to fast convergence rate, high quality non-inferior solution and good Robustness and so no, the PSO algorithm is used for multi-dimension function optimization and objection optimization dynamaticly. So in this paper by MATLAB software, the optimization is developed to evaluate the model.Thirdly, the Monte Carlo method is applied for the uncertainty calculation process. Because of the nonlinear and Non-differentiable of the evaluation model, the transfer function of the uncertainty is very complex, and sometimes can’t be obtained by Analytical Method. So according to the character of orientation error, Monte Carlo method is applied to evaluate the measurement result of uncertainty.Fourthly, the orientation error evaluation method is verified by examples. The dates of parts are obtained by CMM, and then by using V groove as an example, the plane to plane inclination error evaluation is verified. By using some box as an example, the line to plane perpendicularity and the plane to plane parallelism are verified.Fifthly, the orientation error evaluation prototype software system is developed. Based on the mixed programming between VC++ and MATLAB, the orientation error evaluation prototype software system is obtained. The prototype system can not only read the dates from CMM, but also can give the uncertainty of evaluation results when giving the error evaluation results.The prototype is validated by practical use.This research is supported by the Natural Science Foundation of China and the Guangxi key laboratory of Manufacturing System and Advanced Manufacturing Technology.