中文摘要：

为了实现单片集成六自由度微惯性测量单元，提出了一种改进的由4个大质量块和4个小质量块组合而成的四方全对称结构的三轴陀螺仪。介绍了该惯性测量元件的结构及工作原理，根据结构参数计算出了详细的性能指标，并进行了面内驱动模态和面内外的敏感模态仿真。为提高各敏感模态的机械灵敏度，提出采用双重静电频率调谐方案，即先对公共质量块施加凋谐电压，使驱动模态和航向模态的频差最小；再对小质量块上方的多晶硅电极施加另外的调谐电压，最终使四模态频率偏差小于30Hz，从而说明该频率调谐方法是有效的。然后，通过分析热弹性阻尼能量耗散机理，对驱动及敏感谐振模态的品质因数进行仿真。结果表明：真空环境不考虑空气阻尼情况下，两种模态的品质因数分别为23816和19507。最后，基于表面加工和体加工工艺，设计了高深宽比的加T流程。对该四方对称解耦结构的设计和仿真表明其模态匹配和品质因数性能满足三轴陀螺的设计要求。

英文摘要：

A tri-axis gyroscope with the improved square symmetrical structure consisting of four large proof- masses and four small proof-masses was proposed to realize a monolithic six Degree of Freedom inertial meas- urement unit. Firstly, the structure and its working principle of the unit were introduced and the required performance was given by detailed design parameters. Then, the modal analysis for in-plane driving mode and out-plane sensing mode was simulated. To increase the mechanical sensitivity for each sense mode, a dual e- lectro-statically tuning method was adopted. In this method, a tuning voltage was first applied on the proof- mass to make the frequency shift between drive mode and yaw mode as small as possible, and the other tuning voltage was applied on a polysilicon electrode plate over the small proof masses to further make the frequency shift among the four modes to be under 30 Hz. By these, the tuning method was verified to be effective. Fur- thermore, the quality factors for driving and sensirlg resonant modes were simulated through analysis of the thermoelastic damping mechanism. The analysis results indicate that the quality factors in driving and sensing modes are 23816 and 19507, respectively. Finally, a process flow for high aspect was designed combining thesurface and bulk micromachining. The design and simulation for this square symmetrical and decoupled struc- ture demonstrate that the mode matching and quality factor can meet the design requirements for the tri-axis gyroscope.