Mode Localization and Frequency Modulation Sensing Using Superposed in-Phase and Anti-Phase Oscillations

This paper reports on a mode-localized sensor that uses superposed in-phase (IP) and anti-phase (AP) oscillation modes. The IP/AP mode separator was developed to control these modes simultaneously, even when these modes overlap. The modal-shape (amplitude ratio) detection method using the interference signals between AP and IP control loops is proposed and demonstrated. The IP and AP modal shapes as well as resonant frequencies were simultaneously detected, which means the proposed system can also be used as a frequency modulation (FM) sensor.