六自由度奈米平台之設計與控制

Design and Control of A 6DOF Stewart-type Nanoscale Platform

查厚錦(Ho-Chin Jar)

指導教授 ： 丁鏞

中原大學/工學院/機械工程研究所/博士(2006年)

https://doi.org/10.6840/cycu200600880

摘要

本研究為發展以壓電陶瓷致動器驅動之具六自由度史都渥特型式奈米平台，內容包括了精密機構之研製、壓電陶瓷致動器之功能分析、磁滯模型及其前饋控制器之設計、平台運動數模之建立、系統量測校正及誤差補償方法之開發，以及系統之整合並驗證其功能。
精密機構研製之項目包括撓性接頭、壓電致動器、固定下平台及可動上平台，並利用有限元素法ANSYS軟體，分析接頭之剛性、平台之工作空間及其最大應力，找出適合之最佳設計。
利用所設計之動態Preisach模型進行磁滯現象之研究，不僅考慮其靜態行為，並同時分析因輸入電壓變化率所造成之動態行為。以所推導之動態Preisach模型，設計前饋控制器以降低磁滯之非線性影響。
設計工作空間之軌跡規畫，而期望之軸空間腳長值可經由逆向運動學求得。經由所提出之三點三軸量測法可獲得終端夾爪之工作空間變化量。由於製造誤差及組裝誤差的因素，期望夾爪變化量會與真實變化量不同，藉此建立誤差補償模型以校正機構所產生的誤差。
最後以螺旋軌跡進行平台追蹤性能之測試，透過不同行程之實驗，驗證所發展之平台系統能夠達到奈米等級定位之目標。故此設計不需要昂貴之感測器作為回授控制之用，符合經濟有效之實用目標。

關鍵字

前饋控制器 ； Stewart平台 ； Preisach模型 ； 磁滯 ； 撓性接頭

並列摘要

A 6DOF Stewart-type nanoscale platform driven by piezoelectric actuator is developed. In this dissertation, several topics including the precision mechanism design, the piezoelectric actuator function analysis, the hysteresis model as well as its feed-forward controller design, the kinematics modeling, the system measurement and calibration as well as the error compensation method, and the system integration are investigated in this dissertation.
The design and manufacture of precision mechanisms includes the flexure joints, the piezoelectric actuators, and the lower fixed-base platform and the upper movable platform. By means of ANSYS simulation, the stiffness of the joint, and the workspace as well as the maximum stress of the platform are studied in order to attain better design purpose.
The hysteresis phenomenon of the piezoelectric actuator is analyzed by means of proposed dynamic Preisach model, which concerns not only the static analysis, but also the dynamic behavior of the actuator corresponding to the change rate of input voltage. A feed-forward controller is designed based on the proposed dynamic Preisach model to deal with the nonlinear effect.
Path planning in the task-space is designed for practical implementation. The desired joint-space leg length is calculated by inverse kinematics. Variation of the end-effector is measured by the developed 3-points-3-axes method. As a matter of fact, the desired variation of the end-effector is different from the actual variation due to manufacture error and assembly error. Therefore, error compensation model is established for calibration.
The tracking performance of the platform is experimented following a spiral trajectory. From experimental data, it indicates that the developed platform system is able to achieve the target of nanoscale positioning for numerous ranges of manipulating stroke. Therefore, it verifies a cost-effective design with no need of sensor for feedback control for a complex 6DOF platform is practicable.

並列關鍵字

hysteresis ； Preisach model ； Stewart platform ； flexure joint ； feed-forward controller

參考文獻

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