微機電陀螺儀與加速計之量測與分析

Abstract

在微機電陀螺儀的研究中，頻率匹配是一個很重要的議題。因為在高品質因子的情況時，共振頻率的頻寬會很窄且振幅很大。因此，在製程上的精細度會有很高的要求，以達到頻率匹配。通常來說會有幾種方法來解決此問題，一種是具有可調變共振頻率之設計；另一種則是放大操作頻寬。 本論文設計一具有雙去耦合結構及可放大操作頻寬之微機電陀螺儀。此陀螺儀由在驅動端與感測端各三個共振器以交互垂直結構組成。每個共振器以機械微懸臂樑互相連結，使得驅動與感測端能夠藉由共振器的耦合由不同共振模態形成一放大頻寬；在驅動端和感測端之共振器由 U 型質量塊及六個交互垂直之去耦合彈簧連結而成，用來避免兩端震動互相影響。 實驗有兩部分：一為量測驅動端與感測端之共振頻率，並繪製其頻率響應圖，從結果得知我們不僅能夠放大兩端之操作頻率，並且得到良好的頻率匹配；另一為陀螺儀旋轉實驗，從實驗量測電壓輸出與角速度之對應圖表，在共振頻率下隨著角速度的增加電壓輸出也跟著增加，也就是說隨著角速度的增加，元件受到的柯氏力也漸增。反之在非共振頻率下，電壓輸出並未與角速度成正比之變化。 在加速計方面，本論文將探討如何分析一個具有雙重感測機制的微機電加速計的數據，此加速計可同時使用電容式感測以及壓阻式感測來量測加速度。我們的目標是藉由同時用兩種方式量測加速度，並運用數學的方法來減少量測的誤差。

In the research of MEMS gyroscope, frequency matching is an important issue. In the High-Q condition, the bandwidth of resonance frequency is very narrow and the amplitude is very great.So the fabrication has to be accurate. Normally, there are several methods to solve this problem. One is in-operation tuning and the other one is broaden the operation bandwidth. In this thesis, we design a MEMS double-decoupled gyroscope with an enhanced operation bandwidth. There are three oscillators in drive and sense and they are orthogonal structure. Each oscillator is linked together by mechanical coupling beams, and we can broaden the operation bandwidth in drive and sense by coupling different modes. A U-shape proof mass and six orthogonal decoupling springs are used to connect drive unit and sense unit in order to prevent the interference. There are two experiments: One is the measurement of frequency response of drive and sense, and we indeed enhance the operation bandwidth and have a great frequency matching from the result. The other one is gyroscope experiment, we measure the voltage output versus angular rate. At the resonant frequency, voltage output is greater while angular rate is faster. On the other hand, at off-resonant frequency, output voltage doesn’t change while angular rate changes. We talk about how to analyze the data of micro accelerometers using hybrid sensing mechanism. The accelerometer can measure the acceleration by using capacitive sensing and piezoresistive sensing. Our goal is to measure acceleration with two ways of sensing and to reduce measurement error by mathematical method.