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
Related Articles
- EP ID EP149812
- DOI -
- Views 59
- Downloads 0
MODELS OF BIAS OF MEAN SQUARE VALUE DIGITAL ESTIMATOR FOR SELECTED DETERMINISTIC AND RANDOM SIGNALS
The article presents the probability density functions as well as characteristic functions of selected periodic and random signals. On their basis, original models of the bias of the mean square value digital estimator...
MULTITASKING MEASURING SYSTEM OF THE BACKING CALORIMETER FOR THE ZEUS EXPERIMENT AT THE HERA ACCELERATOR<br />
The paper is devoted to the subject of application of a complex measurement system in HEP experiments. The measurement system is electronic, FPGA-based, multi-channel and distributed. The application is the Backing Calor...
LINEARITY ERROR AS COMPONENT OF A/D CONVERTER UNCERTAINTY
Analog-to-digital (A/D) converters are basic elements of measuring chains since they deliver measurement data being a carrier of digital information in measurement instruments and systems. Taking into account that the qu...
PROPOSALS FOR THE NEW DEFINITION OF THE KELVIN
The International Committee forWeights and Measures (CIPM) has had a long-term aim of defining all of the base units in the terms of fundamental physical constants to eliminate any artifact on material dependencies. In 2...
CHARACTERIZATION OF DEAD WEIGHT TESTERS AND COMPUTATION OF ASSOCIATED UNCERTAINTIES: A CASE STUDY OF CONTEMPORARY TECHNIQUES<br />
Estimation of uncertainty associated with pressure, measured by a dead weight tester is a key issue of recent times in pressure metrology. Though two different techniques have been used in the past yet there has been lit...