A Nano-g Electromagnetic Accelerometer With 152-dB Wide Dynamic Range

High precision accelerometers play a vital role in the measurement of the Earth’s gravitational field. They can be used in the rotating-accelerometer-based gravity gradient instrument (GGI) to detect the change of the gravity gradient. For that application, the high precision accelerometers should have a noise floor of below 1
$\text{n}{g}/ (Hz)^{1/2}$
, and both have a measurement range with dozens of
$\text{m}{g}$
for working on a shipborne or airborne moving platform. Therefore, the high precision accelerometers require a wide dynamic range of at least 150 dB. However, the off-the-shelf accelerometers with 150-dB dynamic range cannot meet the requirement of the GGI due to their high self-noise floor. In this article, a metal flexure electromagnetic rebalance accelerometer with both low noise and wide dynamic range is proposed. For the spring-mass structure design, a pair of metal leaf springs is applied to support the proof mass with a fundamental frequency of 8.3 Hz and a large cross-axis rejection ratio of 2913.4. The detailed noise analysis of the proposed accelerometer is conducted to ensure the self-noise of the accelerometer can meet the target noise floor. Finally, the proposed accelerometer is evaluated and calibrated with the results showing the scale factor of (398.6 ± 0.2) V/
${g}$
, the measurement range of ±27
$\text{m}{g}$
, and the self-noise of 0.5
$\text{n}{g}/ (Hz)^{1/2}$
at 0.4–2 Hz. In this case, the dynamic range of the proposed accelerometer can be derived as 152 dB at 0.4–2 Hz, which meets the current requirement of the GGI and other high precision applications.