- 學位論文
大行程共平面晶圓檢測平台之精密二維定位控制
Precision 2D Servo Design for a Large Stroke Wafer Coplanar Inspection Stage
摘要
本論文針對氣浮平台之硬體架構對系統辨識之影響做出分析及改善方法，由於此平台並非安裝在光學桌上，所以環境的震動及干擾無法有效隔絕。取而代之的是採用隔震墊作為抗震方法，但如此一來卻衍伸出另一個問題，隔震墊本身的共振頻率落在輸入訊號的操作範圍內，以至於降低系統辨識之準確性且同時增加數學模型的複雜度。另外，由於此平台由多層組裝而成，因此產生許多影響系統辨識結果之因素。例如在硬體上，Y軸線性馬達搭載在X軸線性馬達上後，又會改變整體平台之頻率響應。為了逐一解決上述問題，本論文將比較在不同硬體架構下之頻率響應。最後以單輸入單輸出(SISO)方式將X軸與Y軸之系統分別辨識出來，並對系統辨識結果中的共振頻率納入控制器設計的考量。 在控制方法上，為了讓系統辨識之結果與實際受控場的差異(uncertainty)不影響到最後定位精準度，本論文採用強韌控制理論來設計 控制器，將整體控制架構之infinity norm壓在某一定值下。如此一來，即使無法完全掌握平台的真實數學模型，也能透過 控制器達到理想的運動流暢性以及精準定位。而控制架構是以狀態回授搭配常數控制器建立而成，其中狀態回授是透過光學尺將位置及速度量測回來以完成閉迴路控制，且以積分控制對位置誤差作收斂。 另外本論文亦採用loop shaping的方式設計控制器，其設計方法與強韌控制最大差別在於從頻域上對受控廠之系統辨識結果設計控制器。而採用強韌控制方法前，必須對系統架構中的每個環節完全掌握，但此平台之驅動器內部架構僅有簡單說明而已，故從系統辨識實驗出來之頻率響應設計控制器，相較於強韌方法較貼近真實情況，且整體設計過程的數學複雜度大大降低。最後將以上兩種方法和驅動器內部的控制器設計演算法做定位精度比較。
並列摘要
This thesis analyze an influence of system identification caused by hardware structure of an air-bearing motion stage. The minute vibration from environment cannot be excluded since this air-bearing stage is not equipped on an optical table. Instead, a vibration isolation pad is adopted to address this issue, but the pad results in another problem at the same time. The resonance frequency of the pad is located in the range of input signal frequency, resulting in the decreased accuracy of system identification and increased complexity of mathematic model. Moreover, due to the stage is assembled by two layers, the result of identification is affected by many pernicious factors. For instance, the frequency response of stage varies after linear motors in Y-axis are mounted on those of in X-axis. To solve these aforementioned problems, this thesis compares the frequency response in different hardware structure. Finally, the system is identified as a single input single output(SISO) system and the resonance caused by hardware is considered in system identification result. To make the difference between identification result and real plant not to affect the positioning accuracy. This thesis adopts robust control theory to design an H infinity controller and restricts the infinity norm of the mathematic model to a certain constant. If the preceding controller is designed, the ideal fluent motion and precise positioning can be achieved via H-infinity controller even the real dynamic response of air-bearing stage is not completely grasped. The control block diagram consists of state feedback with constant controllers. The state used in feedback is measured by linear scale to complete closed-loop control, which includes an integrator to converge the position error in steady state. Besides, the loop shaping is adopted to design the controller as well. Unlike robust control, the design procedure takes place in frequency domain. On the other hand, every details need to be fully comprehended before designing a robust controller. This prerequisite cannot be satisfied since the specification of control block in motor drives is too simple to grasp the control structure. Hence, designing controller from frequency response of experiment result is much more close to real situation. Also, the complexity in math calculation decreased significantly. The result of positioning accuracy from both methods and algorithm for controller tuning in motor drives are compared at the end of chapter.
參考文獻
延伸閱讀
- 李宜達（2007）。精密定位平台之放大機構設計〔碩士論文，中原大學〕。華藝線上圖書館。https://doi.org/10.6840/CYCU.2007.00642
- 王國安（2016）。大行程精密平台之定位控制：結合雙光子聚合技術於大尺寸微結構物之製作〔碩士論文，國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342/NTU201603629
- 朱軒佑（2020）。精密晶圓檢測平台的高度穩定軌跡與速度控制〔碩士論文，國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342/NTU202003862
- 魏民（2018）。大行程晶圓檢測平臺之控制及軌跡精度研究〔碩士論文，國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342/NTU201801378
- 郭晉譯（2010）。Fabrication of Planer Polymer Waveguide Bragg Reflector Device〔碩士論文，國立虎尾科技大學〕。華藝線上圖書館。https://www.airitilibrary.com/Article/Detail?DocID=U0028-0902201009090000