Research On The Capacitive Micro-machined Gyro Process And Detection System Based On Phase-locked Modulation Technology

MEMS gyroscopes have attracted tremendous attention in recent years due to their booming market's needs,especially in automotive industry,navigation system and even tacticalgrade application.MEMS gyroscopes are projected to be a great success as accelerometers before,which push many researchers to dedicate many efforts to develop more miniature,more robust and better performance devices.In the past decades,together with improved mechanical structure design,low noise readout circuits and reformative microfabrication,the control system for MEMS gyroscopes put much more emphasis than ever before to make the gyroscopes possess better sensor performance and the adaptability for environmental parameters' variation.In this paper,based on phase-locked modulation technology,research the capactive maicro-machined gyroscope from the gyro process and control system,the main research as follows:1)The design of the structure and the machining process is the basis of high SNR capacitive micromechanical gyroscopes.The main process difficulty is glass corrosion,CMP chemical mechanical polishing,structural layer pattern preparation and three-layer anode bonding.The experiment process is aimed at maximizing the performance of gyroscope,and as far as possible optimizing the process parameter.2)The widely used PLL-AGC drive technique is optimally designed from the standpoint of transient respose improvement.The control parameters of the gyro transient response are extracted,and the optimal solution is obtained,which makes the gyro transient response time the shortest and no overshoot.And the results of theoretical analysis are verified by simulation.3)In order to improve the gyro bandwidth,it is difficult to drift under the influence of the external environmental factors,and then put forward the force re-balanced closed-loop detection control,and making the theoretical analysis.With the analytical closed-form solutions,the design of transient resposes and bandwidth becomes easily by parameters tuning for force rebalanced gyroscope with mached modes.In order to further improve the performance of gyroscope,the proposed carrier modulation and modal matching control,used to eliminate parasitic capacitance and frequency difference on the performance of gyroscope.4)Because of the gyro multiple control loop needs to run at the same time,and the need for high-precision low-noise electronic components to extract the gyro weak signal,so the FPGA-based HF2LI lock-in amplifier built gyro detection system to achieve high-precision gyro output signal measurement.The gyro excitation signal is obtained by closed-loop drive control,and then the compensation of the gyro zero bias signal and the quadrature error signal is realized by the force recalculation closed-loop detection.At the same time,the signal-to-noise ratio is improved by carrier modulation and modal matching control.The main performance parameters of the gyroscope are tested by using a good control system,including the gyro scale factor,zero bias stability,zero deviation temperature characteristic and driving frequency temperature characteristic.