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微机械石英陀螺敏感元件的设计与制造研究
Research on Design & Manufacture of Sensitive Element of Micromachined Quartz Gyroscope
【作者】 施阳和；
【作者基本信息】 华中科技大学 ， 机械制造及其自动化， 2008， 博士
【摘要】 MEMS是近年来比较热门的一个新兴的技术领域,具有广阔的发展前景。MEMS技术在惯性领域的发展应用催生了微惯性技术。微惯性技术的发展,主要集中在微机械加速度计和微机械陀螺这两大类产品领域内。而微机械石英陀螺是微机械陀螺中发展较快的一种。微机械石英陀螺,是二十世纪八十年代末出现的一种微惯性器件,属于中低精度陀螺。微机械石英陀螺,以其具有的成本低、体积小、结构简单、可靠性高等特点在现代精确打击战术武器的军事方面和民用汽车等非军事方面获得了广泛的应用,显示其是一种非常有前途的微机械振动陀螺。在研究微机械石英陀螺的国内外发展研究现状的基础上,对微机械石英陀螺的设计、制造和振动模式测试等方面进行了深入研究,研究的内容及成果如下:总结和研究了压电石英晶体的材料特性和微机械石英陀螺的动力学问题。指出柯氏力偶引起的扭转运动是实现石英陀螺的机械解耦的关键。同时在深入研究公理设计理论和振动陀螺原理的基础上,提出了振动陀螺的公理设计模型。振动陀螺的公理设计模型解决了陀螺设计中有运动耦合的问题,使得原先一些从经验、甚至直觉发展而来的微机械振动陀螺的设计准则有了科学的依据。这对微机械振动陀螺的规范化设计和创新是有较大的指导意义的。在振动陀螺的公理设计模型的指导下,对微机械石英陀螺的材料特性和现有的微机械石英陀螺结构进行了深入研究,提出了一种新的结构,即微机械梳齿石英陀螺。用有限元方法对其进行了模态研究,并分析了相关尺寸参数对微机械梳齿石英陀螺的振动模态的影响。推导建立了微机械梳齿石英陀螺的集总参数模型并据此开展了驱动模式和感测模式的定量研究。微机械石英陀螺的电路主要是驱动电路和检测电路。选用ADM8660实现升压,并采用专用函数信号发生器XR-2206产生恒频等幅正弦驱动信号。检测电路须实现陀螺元件输出信号的放大、解调和滤波功能。通过电荷放大器和锁定放大器得到了高信噪比的信号。最后运用Matlab对检测电路进行了仿真研究。仿真结果表明,采用锁定放大原理,只要处理好电路中的噪声和滤波的效果就可以得到很高的信噪比。研究了微机械石英陀螺加工制造中涉及到的问题。并结合现有条件,对超声波加工及超声加工石英机理等问题进行了研究。用超声成型加工方法加工出了微机械梳齿石英陀螺基片结构。针对MEMS结构的尺寸微小,共振频率高这一特点,开发研制了MEMS用的多载荷加载台。通过这一多载荷加载台,可以进行基础激励、温度和压力的精确控制,实现不同的真空环境下MEMS的静动态性能测试。同时也据此开展了微机械梳齿石英陀螺的振动模式的研究。
【Abstract】 MEMS is rising new technology in recent years which has a bright future. MEMS promotes micro inertial technology in various applications of inertial field. Micro inertial technology includes micromachined accelerometers and micromachined gyroscopes, etc. Micromachined quartz gyroscope has developed faster than others in micromachined gyroscopes. Micromachined quartz gyroscope is one type micromachined inertial sensor, emerged in 1980s, which is classified to rate grade. Due to its lower cost, small volume, simple structure, high reliability, etc., micromachined quartz gyroscope has promising applications, such as military rate grade devices and non-military civil automobiles.This dissertation placed emphasis on some issues of micromachined quartz gyroscope, based on review of present developments and research of micromachined quartz gyroscope at home and abroad. Design, manufacturing and vibrating testing of micromachined quartz gyroscope presented in this dissertation were summarized asfollows:Material characteristics of quartz crystal and dynamic problems of micromachined quartz gyroscope have been summarized and studied. This dissertation proposes that torsion which has been produced by Coriolis moment is a key to realize machine decoupling of micromachined quartz gyroscope. The axiomatic design mode of the mechanical structure of Coriolis vibratory gyroscope is proposed, based on fundamental study of axiomatic design theory and operating principles of Coriolis vibratory gyroscope. The axiomatic design mode of vibratory gyroscope which resolved coupling problem of gyroscope design, provides scientific rule for micromachined quartz gyroscope design which is based on the experience, even the intuition. The axiomatic design mode has better instruction significance to standardized design and innovation of micromachined vibratory gyroscope.Based on the axiomatic design mode and investigation of material characteristics of quartz crystal & structure of micromachined quartz gyroscope, a micromachined comb quartz gyroscope is proposed in this dissertation. Its vibratory mode has been investigated by finite element analysis (FEA). Meanwhile, the impact of geometry size on vibrating mode has been revealed. Lumping parameter model of micromachined comb quartz gyroscope is established, therefore, quantitative investigation of drive mode and sense mode is conducted.Driving circuit and detected circuit constitute Micromachined comb quartz gyroscope circuit. Voltage rising is achieved using ADM8660. Sine drive signal with constant frequency & coequal amplitude of vibration is obtained using special signal XR-2206. Magnification, demodulation & filting of out signal of gyroscope are carried out by detected circuit. Using charging amplifier and locking amplifier,the signal of high signal-to-noise can be gained. At last, simulation of detected circuit is performed using MATLAB. According to the simulative result, using locking amplifier,high rate of signal-to-noise can be gained as long as deal with noise and filting of circuit. Some manufacturing problems of micromachined quartz gyroscope are studied.Combining present conditions, this dissertation discusses ultrasonic manufacture and manufacturing mechanisms of quartz. Finally, structure of micromachined comb quartz gyroscope is obtained by using the method of ultrasonic manufacture.In terms of structural features of MEMS with small size & ultra high frequency, multi-loading device uesd for MEMS is fabricated. Through multi-loading device,static & dynamic testing of MEMS can be performed in vacuum. Precise control of base excitation, temperature and pressure can be achieved. At the same time, according to the mentioned advantage points, vibrating modal investigation of micromachined comb quartz gyroscope is carried out.
【Key words】 MEMS； Quartz Gyroscope； Axiomatic Design； Ultrasonic Manufacture； Dynamical Testing；