Study On Strongly Parallel Common-Coupled Micromechanical Gyroscope With Orthogonal Dual Ring Layout

Presently,the single mass vibrating gyroscope and vibrating ring gyroscope are the major adopted forms for both mature research and development of the micro gyroscopes.The single mass vibrating gyroscope is featured with high sensitive mass ratio and low cross coupling,while the vibrating ring gyroscope is immune to acceleration/vibration and temperature theoretically.Therefore,a combination of mode characteristics between single mass vibrating gyroscope and vibrating ring gyroscope offers a promising method for high performance micro gyroscope to be compatible with high accuracy and environmental robustness.For this purpose,a strongly parallel common-coup led gyroscope with orthogonal dual ring layout is proposes in this dissertation.In order to implement the structure,a series of key technologies,such as design principles of coupled gyroscope,high performance structure design and optimization,gyroscope manufacture,vacuum packaging and performance analysis,are studied in this work.The specific achievements are summarized below:1)Referring to classical theory of single mass vibrating gyroscope,the sensitivity of multi mass coupled gyroscopes is derived from the simplified structure model Based on the theory of thermalelastic and vibration,the quality factor theory model,such as thermoelastic damping and parasitic mode energy dissipation are investigated,and the optimization schemes are proposed.By system level simulation,the study investigates the influence of coupling on the gyroscope noise behavior.And The theoretical relationship between structural parameters of the coupled gyroscope and the angular random walk is defined.The response model for acceleration/vibration is carried out.By optimization of parasitic/primary mode stiffness and mulit mass layout,the design principles are achieved for the coupled gyroscope to be immune from acceleration/vibration.2)Based on the theory of mechanics and vibration theory,the strongly parallel common-coup led gyroscope is with stiffness hardening in common mode and stiffness softening in differential mode.The coupled gyroscope is also proved to have the capability of adjusting mode asymmetry caused by process error.According to the optimization scheme for thermoelastic damping,a low energy dissipation and high robustness slot structure is achieved.Based on finite element simulation and the numerical analysis,mode frequency/shape,sensitivity and angular random walk are calculated.The anti-acceleration/vibration performance of coupled gyroscope is verified from the three aspects:immune performance by difference method,common mode response,frequency drift characteristics caused by acceleration.And temperature characteristics of frequency and quality factor are achieved by simulation.3)The SOG(silicon-on-glass)structure is developed for gyroscope and unpackaged chip is realized by standard MEMS process.According to the structural features of unpackaged chip,the vacuum packaging solution based on SOG cap is proposed.Besides,the key process for vacuum packaging such as multi-layer bonding technology,deep glass etching,through-vias interconnection metallization are studied.4)The vibration characteristic test system with vacuum chamber and differential input/output is set up.Frequency sweeping method is introduced to characterize the gyroscope frequency/shape,quality factor,nonlinear vibration and asymmetry of multi mass vibration amplitude.Besides,the deviation analysis between the measured data and theoretical design are conducted.Coriolis-effect test system which consists of digital phase-locked amplifier is used to evaluate the sensitivity,bias,acceleration/vibration response and temperature drifts of vibration characteristic.The data base is laid for the future work.