參考模型適應控制在主動式避振系統之應用

Abstract

隨著科技進入奈米時代，產業進入精密與細微化，振動對於精密機電系統造成很大的影響，各類檢測設備與製程設備對於避振的需求越來越高。為了解決振動問題，避振系統廣泛的被使用。被動式避振系統，具有高穩定性及低成本的優點，目前廣泛的被工業界採用，但避振效果有限；主動式避振系統在近年來已經成為避振系統的趨勢，利用額外的致動器達成抵銷振動的效果，對於被動式避振系統不擅長的低頻段也能有很好的抑振效果，然而其缺點在於避振平台上的負載，可能會使得系統閉回路變為不穩定。 此篇論文旨在研究主動式避振系統之振動抑制，並探討避振平台在變動負載下控制器的定位性能。在文中以雷射干涉儀作為感測器，利用音圈馬達響應速度快、運動行為線性的優點，設計一套主動式避振系統。在建構系統模型方面，推導系統動態方程式並利用系統鑑別找出系統之模型。 本研究採用PID控制器與MRAC控制器補償干擾平台所產生的外界干擾，利用Lyapunov穩定理論驗證避振系統閉迴路之穩定性。藉由電腦模擬與實驗，在抑制固定頻率之振動方面，此兩種控制方法成功的消除35.89dB與24.2dB的振動。此外此篇論文探討PID控制器與MRAC控制器在變動負載下的定位性能，PID的定位性能會受限於平台負載，而MRAC控制器對於平台負載之變化有較佳的定位性能。

In semiconductor industry the feature size in integrated circuit devices shrink continuously and the sizes are going from micrometer to nanometer. Vibration influences the precision in micro-electro-mechanical systems greatly. With the advance of technology, the requirement of vibration isolation in inspection equipment and manufacture process equipment is more and more important. In order to solve vibration problem, anti-vibration system is widely used in industry. Passive vibration isolation is popular in industry because of its high stability and low cost, but its performance is limited. There is a tendency toward active vibration isolation(AVI) system in recent years. It achieves the result of anti-vibration by using a additional actuator. It also has good performance in low frequency region where passive vibration isolation system is poor at. But the system could be unstable due to the loading of AVI platform. This research investigates the active vibration isolation issues and the positioning performance under variable loading. In this thesis, we design an AVI system by using laser interferometer as sensor and voice coil motor as actuator having high response velocity and linearity motion. In chapter II, we derive system dynamic equation and identify the system model. The thesis then compares the vibration isolation performance using a classical proportional-integral-derivative (PID) controller versus using a model reference adaptive controller (MRAC). The thesis also derives adaptive law using Lyapunov stability theory. By computer simulation and experiment, these two controllers achieve the maximum attenuation of 35.89dB and 24.2dB with constant vibration frequency. Finally, we discuss the positioning performance to different platform loading. The PID controller positioning performance is easily affected upon platform loading. MRAC controller has better positioning performance in different platform loading.