Instrumentation and Analysis-Methods for the Measurement of Profiles using Light Sectioning

Abstract

This paper presents the instrumentation and analysis methods for the measurement of profiles. The object is rotated in front of a light-sectioning system, which measures the local geometry. A least mean square approximation of the local geometry by a circle is performed, the radius of the circle is used as an estimate for the radius of curvature. The vertical position of the upper tangent to the circle is used to estimate the position of the object. It is shown that the period of revolution can be determined from the aperiodic auto-correlation sequence of the eccentricity of the material. The curve corresponding to the profile of the material is a smooth Jordan curve: this fact is used to take advantage of harmonic filtering to suppress noise and perturbations; and to reconstruct the curve from the radius of curvature. The analysis is performed for both constant rate of revolution and constant arc-length; furthermore, the implementation in MAT-LAB is presented. All methods are demonstrated with real data from industrial measurements.