A closed-loop accelerometer based on three degree-of-freedom weakly coupled resonator with self-elimination of feedthrough signal

This paper, for the first time, reports a closed-loop accelerometer based on three degree-of-freedom weakly coupled resonator (WCR). Three resonators are weakly coupled by two bridge-type coupling beams. When acceleration acts on the proof masses, the stiffness perturbation between the two outer resonators will incur the mode localization and cause the shift of amplitude ratio. The accelerometer is tested under open-loop circuit and closed-loop circuit to obtain the frequency responses and transient responses, respectively. The experimental results show that the sensitivity based on the amplitude ratio readout is improved by 348% compared with the 2-DoF WCR accelerometer. The measured signal-to-ratio noise is 124.2 dB and resolution reaches 1.1μg/√Hz, which are significantly improved compared with the previous works. The resolution and signal-to-ratio noise under closed-loop measurement are improved by 46181% and 123.2%, respectively, compared with those under open-loop measurement which demonstrate that the performance of the mode-localized accelerometer can be improved using the closed-loop measurement method.