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標題: | 運用7軸3D測量機台對複雜工件之精準量測及驗證 3D Coordinate Measurement Machine with 7-DoF Configuration for Precise On-Machine Inspection and Validation of Complex Curvature Workpieces |
作者: | Cheng Li 李晟 |
指導教授: | 羅仁權(Ren C Luo) |
關鍵字: | CNC加工機,量測系統,曲面量測,探針,量測機台, CNC machine,measurement system,surface validation,probe,Coordinate measurement machine, |
出版年 : | 2017 |
學位: | 碩士 |
摘要: | 近年來,CNC robot不斷推陳出新,其功用之廣泛且穩定已使其成為在眾多機器人中成為相當具有潛力的一種,然而在一系列加工流程中,量測為一核心且極具影響力的項目,在許多在精度方面要求甚高的工業中,量測為期提供了品質保證、誤差判定的功效,如在航太業上,飛機機翼是一精度要求極高的大型加工件,且其獨特的設計考量了氣流、風力、風阻等多項因素,一點點加工上的誤差便會改變飛機在空中的穩定性,直接影響了上百人的安全,在小型加工件方面,如齒輪,些微的誤差都會容易造成齒輪旋轉過程中卡住,破壞機械結構使整台機器故障甚至報廢,由已上便可知道量測在加工中是如此重要。此篇碩論提出一就由裝置高精度探針的多軸量測機來玩成對複雜曲面之量測。
多自由度之測量機台搭配冗餘度的特性後可在空間中有著相當大的工作範圍及自由性,其末端點可以在位置不動的情況下改變旋轉以此來確定末端點之探針探測工件表面的的點做量測時可以保證其以法向量觸碰,藉此得到準確的量測數據,大多數的測量機台由於沒有多自由度之特性,常常在以非法向量的方式量測後再額外進行計算出真正的觸碰點位置,此方法的缺點為由於無法真正準確地知道觸碰點與探針末端點的關係,導致難以準確補償物差造成精確度下降。而在量測技術方面,對於ㄧ有複雜曲面之工件的量測往往會由於缺乏參考點而無法找出量測點,此篇碩論中一提出一針對複雜曲面之量測流程,其包括之內容有物件定位、探針半徑補償、曲面量測點取樣、曲面重建、誤差分析及曲面精度分析等。 For these years, CNC(Computer Numerical Control) machine has been developed at an incredibly high speed. Because of its high stability and wide applicability, this kind of machine is considered as the most powerful potential in the future development. In the series of machining procedure, measurement is a core and certainly influential item. For many industries which require extremely high precision of a workpiece, measurement provides the insurance of quality and error decision for each workpiece. Take aerospace industry for example, the airfoil is a large machined part which requires extremely high precision, which is specially designed that considers a lot of factors such as air flow, air mechanics, windage, and so on. Any small error may incredibly influence the characteristics above and decrease the flying stability. Another great example is gear. Stuck is happened while the precision cannot be promised, which may furthermore destroy the whole equipment. This paper proposed a method for measuring a complex surface by a precise probing system mounted on the end-effector of measurement machine with high DoF. For some measuring strategy, they use different sides of the end-effector to measure the points because of the limitation of lower degree of freedom. The merit of the strategy is effectively reflected on lower cost of hardware. However, the difficulty is increased because extra computation is needed for points with inaccessible orientation and position. What’s more, since the error of the end-effector is inevitably affects the real position and command position, the accuracy of measuring value must be much lower. This paper presents an algorithm to explain how to get the normal vector of each point located on the surface of a workpiece and how to avoid the dangerous points which may lead to collision during measuring is presented as well. Finally, the algorithm is implemented on a 7-DoF measurement machine. Thanks to high reliability and high degree of freedom, the machine has extremely wide workspace and a redundant angle to make the end-effector can reach the target even an obstacle exists that may disturb the path of the manipulator. In the measurement technique aspect, a series of measurement procedure will be introduced and explained, including workpiece localization, probe radius compensation, complex surface sampling, surface reconstruction, error analysis and precision analysis of real workpiece. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/2304 |
DOI: | 10.6342/NTU201703313 |
全文授權: | 同意授權(全球公開) |
顯示於系所單位: | 電機工程學系 |
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