Resonance frequency measurement for space accelerometer

Resonance frequency measurements are used for various applications: atomic force microscopes, mass detection, biochemical and inertial sensors. In this article a detailed analysis of the performances of a resonance frequency measurement method are presented and demonstrated using a space grade accelerometer. The method consists of replacing the feedback of the oscillator with a controller that drives the sensor’s input, acquires the sensor’s output, determines the phase shift between the sensor’s input and output, converts it to a resonance frequency measurement and adjusts the drive signal’s frequency. The innovative phase to frequency conversion model used ensures a fast convergence of the drive signal towards the resonance frequency. The maximum measured relative error while searching for the resonance frequency is of 0.04 [%]. The tracking of the resonance frequency shows no oscillations or overshoots because the resonance frequency is exactly measured. The achieved measurement noise floor for the specific sensor used is 0 . 13 [ m H z / H z ] at 1 H z . The measurement method presented can be exploited for other applications which also rely on the measurement of the resonance frequency of a piezo-electric resonator. • Resonance frequency measurement for space accelerometer. • Model-based phase to frequency conversion with self-initialisation. • Noise performance of resonant sensor. • Stable, overshoot-free resonance tracking. • Applicable for other sensors.