Study On Electrostatically Actuated Micromachined Gyroscope

Micromechanical gyroscopes are an important inertial instrument used to measure the angular or angular velocity of an object.It is widely used in consumer electronics,automotive,defense guidance,aerospace and other fields.China’s research in this field lags behind that of developed countries in the West,especially the research on high-performance micro-mechanical gyroscope core devices is still in its infancy.In this paper,a fully symmetrical multi-ring vibration structure electrostatically driven micromachined gyroscope is proposed,which is studied from theoretical basis,working principle,structural design,performance simulation,fabrication technology and device testing,including the following contents:(1)Theoretical study of electrostatically driven micromachined gyroscopes.The theoretical basis of micro-mechanical gyroscope is analyzed in detail,and the mass spring damping model is established.The mechanical properties are used to analyze the performance of the device and the mechanical sensitivity expression is obtained.Based on the principle of micro-mechanical gyroscope electrostatic drive and capacitance detection,the analysis is carried out.Methods to improve the performance of micromachined gyroscopes and focus on electrostatic conditioning.(2)The basic structure design and simulation of the electrostatically driven micromachined gyroscope.By comparing the selection,the multi-ring structure is established as the basic design type of the gyroscope;the modal analysis of the device is performed by computer software,and the resonant frequency of the driving mode is 21052 Hz,and the resonant frequency of the sensitive mode is 21545 Hz.The damping is analyzed.For the influence of device performance,the relationship between different fixed damping ratios and device amplitude is calculated by harmonic response analysis;the influence of external impact on the performance of the device is analyzed.Using the transient dynamics analysis,the maximum acceleration of the device X axis is 8.842 x 105 g and the maximum acceleration of the Z axis is 1.9× 106 g.(3)MEMS process design and flow film experiments of electrostatically driven micromachined gyroscopes.The process based on SOI wafer was designed and flowed;the process of wet etching release structure was optimized;the mechanism of leakage of device substrate was analyzed,and the computer software was used for simulation calculation;the process based on silicon glass bonding was designed.Optimize the glass groove wet etching process design and wafer bonding process.(4)Electrostatically driven micromechanical resonator device testing.The test methods of several main MEMS resonant devices are analyzed.Based on vector network analyzer,vacuum cavity,transimpedance amplifier and other equipment,the device is swept tested.The resonant frequency of the device drive axis is 23686.25 Hz,and the resonant frequency of the sensitive axis is 23980 Hz.Based on the principle of electrostatic regulation,a 2.5V electrostatic tuning voltage is applied to the device,and the frequency cracking of the two modes is reduced from 293.75 Hz to 6.25 Hz,which improves the performance of the device.