A Novel Compensation Algorithm for Thickness Measurement Immune to Lift-Off Variations Using Eddy Current Method

TL;DR

This paper introduces a new algorithm that accurately measures metallic plate thickness using eddy current methods, effectively compensating for lift-off variations to improve measurement reliability.

Contribution

The paper presents a novel compensated peak frequency algorithm that reduces lift-off effects in eddy current thickness measurements, validated through simulation and experiments.

Findings

Measurement accuracy within 2% across lift-offs

Algorithm effectively isolates thickness from lift-off variations

Validated with both simulated and experimental data

Abstract

Lift-off variation causes errors in the eddy current thickness measurements of metallic plates. In this paper, we have developed an algorithm that can compensate for this variation and produce an index that is linked to the thickness, but is virtually independent of lift-off. This index, termed as the compensated peak frequency, can be obtained from the measured multifrequency inductance spectral data using the algorithm we developed in this paper. This method has been derived through mathematical manipulation and verified by both the simulation and experimental data. Accuracy in the thickness measurements at different lift-offs proved to be within 2%.