Research On Testing And Control System Of MEMS Axisymmetric Gyroscope Based On Mode Reversal Technology

In recent years,axisymmetric resonator gyroscopes have gradually attracted much attention in the field of MEMS sensors due to their broad application value and prospects in the fields of aerospace,medical,automotive electronics,and intelligent AI.Disk Resonator Gyroscope(DRG),as a typical structure of axisymmetric gyroscope,has the characteristics of high thermal stability,large conduction area,and low anchor loss.In this paper,a readout circuit with a symmetrical structure and a high Signal-to-Noise ratio(SNR),a control circuit for drive mode and sense mode switching and a force detection circuit based on Correlated Double Sampling(CDS)are designed to improve the bias instability of the cobweb-like disk resonator gyroscopesFirstly,according to the structural characteristics of CDRG,the method of extracting detection signals is researched.After discussing the readout circuit structure and noise,a high SNR interface circuit with a symmetrical structure suitable for signal extraction is designed.Compared with the previous circuit,the readout circuit in this paper uses differential excitation and differential detection to ensure the symmetry of the circuit structure.Secondly,the gyroscopes' double closed-loop control system based on the driving loop and the sensing force-to-rebalance detection loop is analyzed and explored separately,and the shortcomings of the classic double closed-loop control system were summarized.Then,according to the above shortcomings,a mode switching circuit is designed in the conventional force-to-rebalance detection loop,which not only reduces the low-frequency noise of the loop,but also doubles the loop scale factor.Finally,the Coriolis force detection circuit working in mode switching is analyzed in depth,and a Coriolis force detection method based on the CDS principle is proposed to improve the loop gain and bias instability.The experimental results show that the CDRG frequencies of drive and sense mode are 5045.36Hz and 5045.14Hz,and the quality factors of drive and sense mode are 137218 and 140487.The noise equivalent capacitance resolution of the readout circuit is 0.109aF/?Hz.Compared with the conventional force feedback detection circuit,after using the mode switching technology,the scale factor of the detection circuit increased from 7.43mV/°/s to 14.04mV/°/s,and the bias instability(Allan Variance)improved from 1.792°/h to 0.857°/h,and Angle Random Walk improved from 0.272°/?Hz to 0.156°/?Hz.