Research On Control Technology For Micro Hemispherical Gyroscope Based On Force Rebalance Detection

As a newly developing gyroscope,Hemispherical Resonant Gyroscope is honored as the most potential Coriolis vibration gyroscope in this century because of its highly symmetrical harmonic oscillator without any wear components and advantages of stable physical properties,great reliability,long operation life,high radiation resistance,fast starting speed and superior impact resistance.The application of Micro-Electro-Mechanical Technology has reduced the structure of the hemispherical gyroscope's oscillator to microscale,making it develope towards miniaturization,intellectualization,integration,multi-functionalization,lightweight and low power consumption.This research on micro-hemispherical gyroscope is conducted to study the quadrature error,mode mismatch,and temperature drift in depth.Hence,a digitizing system based on the method of close-loop driving and force-rebalance detection is completely designed.The main research contents are as follows:(1)The research on digital system of micro-hemispherical gyroscope with the method of force-rebalance detection.According to the basic theory of gyroscope including its dynamics equation,the Force-Rebalanced detection circuit based on the PI controller is designed in this system.Besides,the simulation models of the designing system are formed to analyze its static and dynamic characteristics and obtain the parameters,which guarantee the close-loop stability.Finally,the design is implemented to the system.(2)The research on the quadrature error of the micro-hemispherical gyroscope.The structural asymmetry is regarded as mass disturbance and stiffness disturbance to establish the dynamic equation of the imperfect micro-hemispherical gyroscope and analyze the interference on the gyroscope detection caused by coupling error.Then the electrostatic force equation of the out-of-plane capacitance of the micro-hemispherical gyroscope is deduced to introduce the principle of orthogonal stiffness correction.Thus,the closed-loop control circuit of orthogonal stiffness correction is applied to the measurement and control system.(3)The resolution of mode mismatch and the improvement on scale factor.Based on the dynamic equation of the imperfect micro-hemispherical gyroscope,the relationship between the mass and stiffness imperfection with the resonant frequency of the driving mode and detection mode and with the detection sensitivity is observed.Moreover,the equation of electrostatic force of out-of-plane capacitor is analyzed to introduce the solution of mode mismatch,which is referred to as electrostatic tuning.Based on this principle,the mode match is realized and the scale factor is improved.Then the temperature drift of the scale factor is analyzed,and temperature compensation is realized in the measurement and control circuit.(4)The design of a low-noise high voltage module.A low noise high voltage power module is designed to solve the problem of power supply in driving,detection and tuning,avoiding the noise that may be introduced by power supply.(5)The performance test of micro-hemispherical gyroscope.According to the testing rules of the domestic MEMS gyroscope,the performance test of a prototype of MEMS hemispherical gyroscope is carried out.The experiments indicate that part of preliminary performance of MEMS hemispherical gyroscope is significantly improved by applying the techniques of orthogonal stiffness correction,electrostatic tuning and force balance detection.The laboratory research of micro-hemispherical gyroscope is still in its infancy,where the performance and the effect of error suppression are preliminary.Thus,this research is desired to accumulate experience and indicate the direction for further research.