Tilt-Induced Noise Improvement of a Nano-g MEMS Accelerometer for Lunar Seismograph With Omnidirectional Deployment

China’s Lunar Exploration plans to deploy a Lunar Seismograph on the moon’s surface to detect moonquakes. Given the unknown inclination angle of the lunar landing, these sensors must possess the capability to adapt to different slopes. This article introduces an MEMS accelerometer that is capable of automatic leveling with omnidirectional deployment. Unlike traditional high-precision accelerometers, which require manual or motorized leveling at a large tilt angle, this accelerometer achieves leveling without any mechanical leveling system. In this article, a precise theoretical noise model is established, and by measuring each noise source against their theoretical noise gains, a total theoretical noise floor is calculated. The theoretical noise floor aligns perfectly with the actual measured noise floor, validating the correctness of the model. The noise tests indicate a noise floor reaching
$3~\rm {ng/\sqrt {Hz}}$
@1–30 Hz, with low-frequency noise performance achieving
$20~\rm {ng/\sqrt {Hz}}$
@0.01 Hz. The dual-axis turntable tests demonstrate that the accelerometer can work at any angle. Furthermore, it clearly detected earthquake signals of M5.5 from distances over 2000 km, matching the signals detected by a co-located commercial seismometer with a residual of 8.6 ng. This article provides new insights into the leveling system design of subsequent MEMS accelerometers or seismometers.