A Sensor Fusion Strategy to Compensate Lift-off Noise for Eddy Current Testing

Eddy Current Testing (ECT) has been extensively employed in non-destructive testing for the detection of defects. However, variations in lift-off distance of the ECT probe during inspections can lead to signal fluctuations that possibly obscure defect identification. To address this challenge, a novel lift-off suppression method utilizing an accelerometer-assisted sensing probe is proposed. The accelerometer integrated in the ECT probe measures the probe’s acceleration, allowing for lift-off distance estimation and further compensation. To further enhance this compensation, a Kalman filtering-based zero-lift-off updating algorithm is developed, improving the accuracy of lift-off distance estimations. Experimental results demonstrate a substantial reduction in lift-off noise, with average lift-off noise peak amplitudes reduced by 9.26 dB to 22.01 dB compared to raw signals. Additionally, the impact of excitation frequency on lift-off suppression performance and defect detection capability is investigated.