A Fast Self-Calibration Method for Piezoelectric Sensors Excited by Pseudorandom M-Sequence

Piezoelectric element is the most critical component of a piezoelectric sensor, commonly applied for defect detection of electrical equipment. To ensure the sensor works stably and reliably, impedance and sensitivity response curves should be calibrated periodically with specific technical platforms in the laboratory to evaluate the sensor's performance and characteristics. This is costly, time-consuming, and inconvenient for industrial measurements. Pseudorandom M-sequence is a kind of binary signal that exhibits statistical characteristics similar to white noise. This article proposes a fast self-calibration method based on pseudorandom M-sequence, which is suitable for acquiring the impedance and sensitivity response curves of piezoelectric sensors. The clock pulse frequency of M-sequence can be adjusted to match the calibration band. The simulation and experimental results confirm that this method is feasible, reliable, and efficient in terms of both power and time consumption, requiring a few milliseconds and approximately 10 mW for a single calibration. The method was successfully applied in a commercial AE sensor and a recently developed wireless piezoelectric sensor. This work provides a novel solution for the self-calibration of smart piezoelectric sensors.