可寬頻操作且具備高感測靈敏度之微機電去耦合陀螺儀的設計與製作

Abstract

隨著自動化科技與導航技術的進步，陀螺儀在體積小、價格低、系統整合度高的需求下，應用微機電製程製作的微型化振動陀螺儀開啟了新式陀螺儀的發展。利用微機電陀螺儀的定位功能，在民生工業以及消費性電子商品上有許多應用，而在學術上的研究亦有許多突破與創新。 微機電振動型陀螺儀的主要原理為：利用轉動發生時造成垂直於驅動端振動方向的科氏力致使感測端產生振動，藉由讀取感測端訊號進行角速度的量測。為提高靈敏度，在結構上採用去耦合型態之概念，而驅動端與感測端共振頻率的匹配、品質因子皆為重要的考量因素。 本論文之研究目標為在不犧牲Q值的情況下，使驅動端與感測端具有頻寬放大的功能，以提高元件之靈敏度。文中將提出具有去耦合結構的兩種微機電振動型陀螺儀的設計：第一種為環形振盪結構，利用四個質量大小不同的質量塊使驅動端頻寬獲得等效放大；第二種為交互垂直振盪結構，利用機械微懸臂樑的耦合方式，隨著頻率增加，使驅動端與感測端因相鄰振動模態的譜線疊加而達到頻寬放大的效果。 文中將進一步利用模擬軟體進行上述兩種結構之共振頻率以及線性動態的模擬分析，觀察其頻譜響應之結果圖型，進行頻寬放大，提高匹配程度功能的驗證。透過L形振盪塊共振頻率實驗的初步測試，頻譜響應與模擬結果可相呼應，也證實所設計的元件確實有頻寬放大的效果，匹配程度得以提高，目標功能初步達成!

Due to the progresses of the automation and the navigation technology, applying MEMS manufacturing process to produce miniaturized vibratory gyroscope begins the development of novel gyroscopes with the requirement of small volume, low prices, and high compatibility to systems. There are many applications in commercial electronic commodities and many breakthroughs in academic studies by the positioning function of gyroscopes. The main mechanism of the vibratory MEMS gyroscopes is that when rotation occurs, the Coriolis force which is vertical to the driving vibratory direction makes the sensing mass vibrate. Thus, we can detect the angular velocity by reading the output signal from sense. We adapt the concept of the decoupled structures for raising sensitivity. In addition, the matching between drive and sense, and the quality factor (Q) are both important considerations. The target of this study is to increase the bandwidths of the frequency responses of drive and/or sense to improve the sensitivity of the designed devices without sacrificing Q factors. Two kinds of designs of MEMS gyroscopes with decoupled structures will be presented in this thesis. The first is circularly vibratory structure which has four different-weighted masses to equivalently increase the bandwidth of driving frequency response. The second is perpendicularly vibratory structures which, with gradually increasing frequency, make the spectrums of adjacent vibration modes of drive or sense be broadened via the coupling of micro-mechanical elastic beam. We use simulation software to analyze the natural resonant frequencies and the dynamic responses of these two kinds of structures, and then observe the resultant diagrams to verify the bandwidths enlargement function. Through the initial experiments of the resonant frequency of L-shape’s vibratory mass, the consequences can correspond to the simulation results. It is proved that the designed devices indeed have the bandwidth-magnified effect, and lead to the rise of matching between drive and sense. Therefore, the goal is initially achieved!