Research On Digital Test Circuit Of Miniature Hemispherical Resonant Gyroscope

Micro hemispheric resonant gyro has the advantages of simple structure,long life,high reliability,resistance to radiation and shock,low mechanical loss,easy maintenance,etc.It has a wide range of application prospects in the fields of aerospace,automotive and military industry.At present,the hemispherical resonant gyro developed in China mostly adopts analog control detection,but the analog circuit has poor anti-interference ability,large drift error,instability and other factors,which cannot meet the requirements of gyro testing.The digital circuit has the characteristics of high reliability,good stability,highly integrate and convenient for computer processing compared with the analog circuit.In this paper,we take the homemade micro-hemispheric resonant gyro as the research object,mainly the PCB design of front-end interface circuit,and the research of micro-hemispheric resonant gyro control and detection circuit system based on FPGA.Firstly,the status of domestic and international research on micro-hemispheric resonant gyroscope and its measurement and control circuit system and the basic working principle and mode of micro-hemispheric resonant gyroscope are introduced,then the driving and detection structure of micro-hemispheric gyroscope is analyzed,the driving and detection mode is determined and the electrode configuration is carried out.The finite element simulation of the resonator is carried out to obtain the second and third order simulation modes of the resonator,and the circuit system of the micro-hemisphere gyroscope is determined to adopt the second-order four-wave abdominal operating mode and resonant frequency.Considering the extremely weak signal output from the front end of the hemispherical resonant gyro,the readout of the front-end electrode signal and the performance of the preamplifier will affect the accuracy of the hemispherical resonant gyro.Based on comparing the performance of the readout circuit structure of the front-end weak signal,it is determined that the charge amplifier circuit is used as the weak signal readout circuit.The study of the stability of the front-end charge detection circuit of the interface circuit is inferred and elaborated in more detail.The overall structure of the control and detection circuit is designed according to the characteristics and control mode of the micro-compact hemispherical resonant gyro,and the closed-loop control and detection circuit in force balance mode is determined through analysis.The structure of phase locked loop,automatic gain control loop,quadrature control loop and force balance control loop are designed and simulated in Simulink respectively,and the interface circuit is designed and tested to verify the correctness of the design.Based on the above research,FPGA is used as the core-processing unit of the whole circuit to realize the combination of interface circuit PCB,digital circuit measurement,and control system to complete the control and detection of the whole closed-loop system.The performance test of the whole circuit system is carried out through the experiment,the resonant frequency of the micro-miniature hemisphere resonant gyro is 6.12836 k Hz,and the Q value is 2665.