Evaluation of Minimum Zone Straightness by Nonlinear Optimization Method

Fitting algorithm is considered one of the significant uncertainty factors to the measurement results using CMM. In this paper, a new algorithm, named Nonlinear Optimization Method (NOM) has been developed for the evaluation of straightness error. To improve the accuracy, efficiency and robustness of NOM, data filtering and rebuilding are incorporated in the method. The algorithm, Least Squares Method (LSM) and Convex Hull Method (CVH) are applied to data sets obtained with CMM measurements on the surfaces machined with different processes such as milling, planning, grinding and hand-finishing. Practically valuable results have been obtained and the algorithm has proven to guarantee Minimum Zone Evaluation (MZE) of straightness.