Contact Coordinate Measurements of Free-form Surfaces: A FIS for Optimal Distribution of Measurement Points

Abstract

The coordinate measuring technique uses different measurement strategies, which may involve, e.g., the distribution of measurement points on free-form surfaces (FFSs) of products. Measurement points must be located on products’ surfaces, in order to measure the quality of workpieces. The most popular method for selecting locations of measurement points on free-form surfaces is uniform distribution. This method is classified as a blind strategy and does not take into account e.g., the accuracy of a workpiece’s machining process. This study focuses on the possibilities of avoiding the use of blind strategies for distributing points to measure the accuracy of FFSs with the support of fuzzy set theory. The input variables for the developed fuzzy inference system (FIS) are an area of a patch of a measured FFS and a deviation observed on a particular patch of an investigated surface (i.e. a mean deviation of a patch of a surface, calculated between a machined surface and its nominal model). The output variable of the FIS is the number of measurement points distributed on patches of FFSs.