A low self-noise accelerometer based on piezoelectric bimorphs

A biaxial differential piezoelectric accelerometer utilizing piezoelectric bimorphs is researched devoting to developing low-noise, low-cost and compact inertial sensors used in airborne acoustic vector sonobuoys. Working model of the accelerometer in the acoustic vector sensor is analyzed theoretically, and self-noise reduction methods of the accelerometer using a bimorph structure and independent mass are proposed according to the theoretical self-noise model. The sensitivity and resonance frequency of the accelerometer are optimized by the finite element method, and the structural parameters of components are obtained. An accelerometer prototype and the associated preamplifier are developed on the basis of optimization results. Experimental results show that the overall size of the piezoelectric accelerometer is 56 mm×56 mm×35 mm, and the resonance frequency is about 7.4 kHz. The two-axial sensitivities are 1556 pC/g and 1363 pC/g (100 Hz) respectively, and the transverse sensitivities are less than 2 % of the axial sensitivities. The self-noise of the piezoelectric accelerometer is 38 ng/√HZ (1 kHz, the equivalent noise sound pressure level is 39 dB/√HZ), which is lower than the ambient sea noise of zero sea state. © 2020, Editorial Department of Journal of Chinese Inertial Technology. All right reserved.