A Simple Acoustic Method for Modal Parameter Measurement of the Resonator for Vibratory Shell Gyroscope

In this paper, an acoustic method measuring the frequency split, quality factor and modal deflection of the resonator for vibratory shell gyroscope (VSG) is presented. This method is based on the superposition and decomposition of acoustic waves generated by standing wave eigenmodes of the resonator. The acoustic signals from an imperfect resonator comprise two standing waves of different frequencies and orientations. Theoretical study shows that the oscillating period and trough-peak ratio of the composite acoustic wave are strongly related to the modal parameters of the resonator. Therefore, the modal parameters of the resonator can be obtained via parameter fitting of the acoustic signal. The measurement error due to vibration drift is also analyzed in the theoretical study. The proposed method could be a simple and fast way to measure the main modal parameters of the VSG resonators without using sophisticated or costly equipments. Experiments were implemented to identify the modal parameters of a typical cylindrical resonator using the acoustic method. For the sake of comparison, traditional electrical and optical methods were also employed to measure the modal parameters. The experimental results show that the modal parameters measured by the acoustic method are close to those obtained from the traditional methods.