A Fast Evaluation Method for Flatness and Straightness Tolerance by Means of Incremental AlgorithmYUE Wu-ling, WU Yong College of Mechanical Engineering, Nantong University, Nantong, Jiangsu 226007, ChinaAbstract:A fast and accurate method called incremental algorithm is proposed to implement the minimum zone tolerance for evaluating flatness or straightness errors. The algorithm is based on the convex - hull theory in computational geometry and also explores the properties of the measurement data. The algorithm starts from a subset with four （three） measurement points. If the bounding flats or straights determined by current subset can cover the whole remaining set, the distance between the bounding planes （lines） is the final accurate flatness （straightness）. Otherwise, put the point with maximum distance from the bounding planes into current subset, and repeat the previous step for the new subset. It is proved that the sequence of flatness （straightness） of these subsets monotonously increasingly converges to the accurate result. The timing complexity is only O （n1）. Several examples verify the correctness of this algorithm.[著者文摘]
