Location

Santa Cruz, CA

Start Date

1-1-1984 12:00 AM

Description

A technique involving the use of Fourier descriptors for characterizing impedance plane trajectories to facilitate defect classification is presented. The Fourier descriptors are obtained by expanding the complex contour function in a Fourier series. Functions of Fourier coefficients which are invariant under transformation of the trajectory are derived and incorporated into a feature vector. Defect classification is obtained by using the K-Means algorithm to cluster the feature vectors. The principal advantage of the approach lies in the ability to reconstruct the curve from the coefficients. Other advantages include the insensitivity of the descriptors to drift in the eddy current instrument as well as variations in probe speed. Experimental evidence attesting to the ability of the approach to discriminate between trajectories and hence identify defects is presented.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

3A

Chapter

Chapter 3: Eddy Currents

Section

Sizing

Pages

589-603

DOI

10.1007/978-1-4684-1194-2_56

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Fourier Descriptor Classification of Differential Eddy Current Probe Impedance Plane Trajectories

Santa Cruz, CA

A technique involving the use of Fourier descriptors for characterizing impedance plane trajectories to facilitate defect classification is presented. The Fourier descriptors are obtained by expanding the complex contour function in a Fourier series. Functions of Fourier coefficients which are invariant under transformation of the trajectory are derived and incorporated into a feature vector. Defect classification is obtained by using the K-Means algorithm to cluster the feature vectors. The principal advantage of the approach lies in the ability to reconstruct the curve from the coefficients. Other advantages include the insensitivity of the descriptors to drift in the eddy current instrument as well as variations in probe speed. Experimental evidence attesting to the ability of the approach to discriminate between trajectories and hence identify defects is presented.