Data processing: measuring – calibrating – or testing – Calibration or correction system – Length – distance – or thickness
Patent
1996-11-29
1999-06-29
Barlow, John
Data processing: measuring, calibrating, or testing
Calibration or correction system
Length, distance, or thickness
702159, C30B 1520
Patent
active
059181966
ABSTRACT:
The invention provides a method for visually monitoring the radius of an item which is rotating about a fixed axis and which has a trackable contour known to lie in a plane normal to the rotation, such as a part turned on a lathe. The present invention can also estimate the cross-sectional diameter of a growing crystal, and the height of the cross-section above the melt surface. In addition, the height and radius of the meniscus at the crystal/melt interface can be tracked by the system of the invention. The present makes it possible to further automate crystal growing processes in a manner that increases manufacturing efficiency, consistency, and overall quality. In general, the invention provides a machine vision method for estimating both a longitudinal position and a radius of a circular cross-sectional feature of a solid of revolution. The method includes the steps of acquiring an image of a circumferential feature of the solid of revolution using a camera having a focal length and disposed at a position characterized by a plurality of position parameters, and then finding a set of points along the image of the circumferential feature. The next step is determining an equation of an ellipse that substantially fits the set of points to provide a plurality of ellipse parameters, and then computing the longitudinal position and the radius of the circular cross-section of the solid of revolution using the focal length, the plurality of position parameters, and the plurality of ellipse parameters.
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Barlow John
Cognex Corporation
Miller Craig Steven
Weinzimmer Russ
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