Jia-chun LIN(林家春)1, Michael Krystek2, Zhao-yao SHI(石照耀)1
1. College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing 100124, China;2. Physikalisch-Technische Bundesanstalt, Braunschweig D-38116, Germany
Abstract-Recently, Coordinate Measuring Machines (CMMs ) are widely used to measure roundness errors. Roundness is calculated from a la rge number of points collected from the profiles of the parts. According to the Guide to the Expression of Uncertainty in Measurement (GUM), all measurement res ults must have a stated uncertainty associated the them. However, no CMMs give t he uncertainty value of the roundness, because no suitable measurement uncertain ty calculation procedure exists. In the case of roundness measurement in coordin ate metrology, this paper suggests the algorithms for the calculation of the mea surement uncertainty of the roundness deviation based on the two mainly used ass ociation criteria, LSC and MZC. The calculation of the sensitivity coefficients for the uncertainty calculation can be done by automatic differentiation, in ord er to avoid introducing additional errors by the traditional difference quotient approximations. The proposed methods are exact and need input data only as the measured coordinates of the data points and their associated uncertainties.
Key words-measurement uncertainty; roundness; automatic diferentiation
Manuscript Number: 1674-8042(2010)03-0224-04
dio: 10.3969/j.issn.1674-8042.2010.03.05
References
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