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Coordinate
measurement systems (CMSs) dominate dimensional control and
diagnostics of various manufacturing processes. However, CMSs
have inherent errors caused by the lack of tracing ability for
some of the measured part features, which are important for
product inspection and process variation reduction in number of
automated manufacturing systems, such as for example automotive
body assembly process. The lack of tracing ability of feature is
such that instead of measuring the given feature, the CMS may
actually measure the area around the selected feature. In our
research, a principle of part feature tracing ability and
resultant feature-based measurement error analysis are
investigated to estimate the aforementioned deficiencies in the
CMSs. Our research explores the impact of feature type and part(s)
positional variation on the feature-based measurement error [26].
The proposed approach is applicable for both contact and
non-contact CMSs including coordinate measuring machines (CMMs)
and optical coordinate measuring machines (OCMMs). Our research
shows that the developed feature-based measurement error can have
significant impact on the accuracy of measurements and on process
control and diagnostics algorithms currently used in
manufacturing. |