Uncertainty Evaluation of Circularity Error Measurement Based on Coordinate Measuring Machine.

Shaft part is widely applied in robots and its circularity error is directly influence the operation accuracy of robots. To rapidly and accurately measure and estimate the circularity error, this paper gives an uncertainty assessment method of circularity error based on coordinate measuring machine (CMM). Firstly, we propose a differential-evolution (DE) optimization algorithm to evaluate circularity errors according to the fitting algorithm of the minimum-zone criterion. Fewer parameters, fast convergence and high accuracy are the characteristics of this algorithm. Secondly, based on the appropriate sampling points, the minimum zone circularity error is computed by the DE algorithm. Thirdly, uncertainty and coverage interval under 95% coverage probability of circularity error are provided and the uncertainty is evaluated based on Monte Carlo Method (MCM) and Guide to the Expression of Uncertainty in Measurement (GUM), respectively. Finally, many experiments are conducted and the conclusion has verified that the suggested method is valid and feasible. Furthermore, it is able to provide some references to other form errors such as flatness error.