DETERMINING THE UNCERTAINTY OF FITTING DISCRETE MEASUREMENT DATA TO A NOMINAL SURFACE
Journal Title: Metrology and Measurement Systems - Year 2008, Vol 15, Issue 4
Abstract
Coordinate measurements are a source of digital data in the form of coordinates of measurement points with a discrete distribution on the measured surface. Geometric deviations of freeform surfaces are determined at each point as normal deviations of these points from the nominal surface (a CAD model). The calculations are preceded by fitting the measurement data to the CAD model. The relations between the workpiece coordinate system and the coordinate system of the machine are described by the transformation parameters. This paper presents the idea of the process of data fitting with the use of the least square algorithm method as well as the way of determining the uncertainty on the assumption that transformation parameters are subject to a cumulative normal probability distribution. The theoretical issues were verified by experiments carried out on a freeform surface obtained in the milling process and characterized by quasi-random geometric deviations.
Authors and Affiliations
MAŁGORZATA PONIATOWSKA
Keywords
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