新型電磁致動與減震之三自由度撓摺結構精密定位平台

Abstract

本論文提出一種以電磁力產生驅動與減低結構振動的平面式定位平台，可用於精密定位相關應用。平台本體採用一體成型之平行撓性結構做為導引機構，其運動來自結構本身的彈性變型。藉著一個近似均勻強度的磁場與四組線圈，本論文提出一種線性電磁制動器的設計，做為提供驅動平台移動與轉動的力量來源。為了減輕撓性結構天生的共振問題，亦提出了以渦電流效應提高系統阻尼的電磁式阻尼器，其非接觸式的特性較一般接觸式的阻尼器更適合用於本論文所訴求之精密運動控制系統。本新型精密定位平臺達成三大目標：第一，擁有大移動行程的能力（此指公釐的範疇）; 第二，精密定位的能力; 第三，採用簡潔的機構設計。 為了要在系統參數變化與外在擾動干擾下達到系統穩定與強健性的目標，本論文提出一個強健適應性滑動模式控制器，提升系統在定位與循跡需求上的效能。控制器包含具有強健性的滑動模式控制器，與線上估測系統參數同時調變控制器的適應律。本論文設計的平台最大行程可達到3x3mm2，定位解析度為10μm。透過在時域與頻域上的分析，撓性結構的共振現象可以有效地被渦電流阻尼器減輕。實驗結果亦證實本論文所設計之平面精密定位平台具有所訴求之精密定位與循跡之能力。

This thesis proposes a novel planar electromagnetic actuated and damped positioning stage for precision positioning applications. The moving stage is suspended by the monolithic parallel flexure mechanism, whose motion comes from the elastic deformation of the flexure. A linear electromagnetic actuator which consists of a near-uniform magnetic field and four coils is designed and implemented to provide the propelling force and torque for 3-DOF motions. In order to suppress the vibration of the flexure suspension mechanism, an eddy current damper is designed and integrated with the electromagnetic actuator. Since the electromagnetic damper experiences no contact, it is obviously more adequate than other kinds of contact damper to be incorporated into precision motion control. The three salient features of the novel system design in the research include: (1) to have large moving range (in mm level), (2) to achieve precision positioning, and (3) to design a compact mechanism. For the purpose of gaining system robustness and stability, a robust adaptive sliding-mode controller is proposed to enhance the system performance for both regulation and tracking tasks. The developed robust adaptive control architecture consists of two components: 1) sliding mode controller, and 2) robust adaptive law. With the designed controller, the stage can achieve high positioning resolution, where the tracking error in each axis is kept within 10μm. Experiment results show the vibration of the flexure mechanism can be suppressed by the eddy current damper successfully in a series of time-domain and frequency domain tests. Besides, the designed traveling range of the positioning stage is 3mm x 3mm in planar motion, and tracking and contouring performance are also examined to assure the appealing dynamic property of the stage.