- 學位論文
應用於逆向工程系統之CMM量測精度改善研究
Accuracy Improvement of Coordinate Measuring Machines Applied to Reverse Engineering Systems
摘要
本論文研究目的係以目前三次元量測系統的既有功能，提出一個可應用於逆向工程系統之CMM量測精度的改善方法。其具體步驟是由初步CMM量測所建立的曲面，取得規劃的點資料，藉由求得這些點資料的法向量方向，驅使量測測頭沿著點的法線向量再度進行量測，進行正確的測頭半徑補償，以改善因不正確接觸點所引起的補償誤差問題。在本論文中先以標準球量測的範例來說明本研究的方法，並配合實際標準球的尺寸來做誤差比對，以驗證本研究方法的正確性。其次，再以兩個B-spline自由曲面的量測範例，說明此量測方法的可行性。經由反覆量測的結果顯示，應用本方法可將CMM的量測誤差有效地減小並收斂至數微米(μｍ)的量測誤差範圍。最後，本研究方法可應用於金屬材質自由曲面等適合以三次元量測方法之工件，除提升量測精度外，也適合將本研究結果整合目前常見的非接觸式量測法，以符合對於各種不同工件材質的量測需求。
並列摘要
This thesis aims to present an effective method to improve measurement accuracy of a CMM applied to the reverse engineering system based on operational functions of the current CMM. Measuring steps include the construction of a preliminary surface formed by initial CMM measurement, obtaining spatial data of planned points on the surface, deriving the normal vectors of these planned points, driving probe movement along the normal vectors for another measurement and completion of accurate radius compensation for the probe head, such that all steps are able to reduce the compensation errors caused by incorrect contact points assumed. For instance, a standard sphere is taken as a example to demonstrate and verify the research methodology by using the fitting method between point data and the target surface. Next, two usual examples made of B-spline surfaces are successfully completed for the proof of research feasibility. It is clearly indicated that measuring errors can be rapidly decreased and converged to several micrometers through repeated measurements. Finally, the studied method can be applied to metal-based free-form components suitable for CMMs. In addition to accuracy improvement, the research is able to integrate the non-contact optical measuring systems to meet various measurement requirements for a variety of work-piece materials.