Wide Temperature Range and Low Temperature Drift Eddy Current Displacement Sensor Using Digital Correlation...

Area of Science:

• * Instrumentation and Measurement Science
• * Sensor Technology
• * Signal Processing

Background:

• * Conventional eddy-current sensors offer contactless measurement, high bandwidth, and sensitivity for applications like micro-displacement and rotational speed sensing.
• * A key limitation of traditional eddy-current sensors is their susceptibility to temperature drift, impacting measurement accuracy.
• * Overcoming temperature-induced inaccuracies is crucial for reliable sensor performance in diverse environmental conditions.

Purpose of the Study:

• * To design and evaluate a differential digital demodulation eddy current sensor system.
• * To mitigate the impact of temperature drift on sensor output accuracy.
• * To achieve high precision and flexibility in eddy current sensing for applications with significant temperature variations.

Main Methods:

• * Implementation of a differential sensor probe to cancel common-mode temperature interference.
• * Digitization of differential analog carrier signals using a high-speed Analog-to-Digital Converter (ADC).
• * Amplitude information extraction via a double correlation demodulation method within a Field-Programmable Gate Array (FPGA).

Main Results:

• * The developed sensor demonstrated a nonlinearity of 0.68% within the ±2.5 mm range.
• * Achieved a high resolution of 760 nm and a maximum bandwidth of 25 kHz.
• * Exhibited significant suppression of temperature drift compared to conventional analog demodulation techniques.

Conclusions:

• * The differential digital demodulation eddy current sensor system offers high precision and low temperature drift.
• * The sensor's design provides enhanced flexibility for applications experiencing large temperature fluctuations.
• * This advanced sensor system can effectively replace conventional sensors in challenging, temperature-variable environments.