機械手臂絕對精度校正技術

Abstract

雖然機械手臂應用於工業中已行之有年，然而現今機械手臂於產線大多仍然仰賴教點方式進行調教，也因此著重於重複精度(repeatability)的水準，如此雖可應付工業界許多的需求，但若要讓機械手臂進入到更多應用範疇的話，如此的作法有所不足。以CAD-based製造生產的角度來看，面對複雜路徑的加工製程若要有好的生產品質，需建立在機械手臂在空間座標系中有足夠好的絕對精度的基礎之上，簡而言之，若下達一個空間中的座標命令，機械手臂是否能準確地到達命令位置呢？且在相同的命令下，同樣型號的機械手臂是否能準確地到達同一位置而不需要重新教點呢？還是會有微小的差距導致錯誤呢？ 本論文提出串聯式(serial)機械手臂絕對精度的校正方法，以高精度的雷射追蹤儀(laser tracker)作為量測以及校正工具。最後提供真實環境下的實驗結果，比較機械手臂絕對精度提升前後的差異，證實所提方法的可行性並且由此說明機械手臂絕對精度校正的重要性。

Robot manipulator have been used for many decades in industrial uses, however, people nowadays still rely on the “teach and learn” method. This is the reason why the specification of robot manipulator only emphasizes on repeatability of pose, instead of the accuracy of pose. Although it somehow meets the requirements in industrial, it is not enough for further applications. For the aspect of CAD–based working, we need robot manipulator with high accuracy of pose in the workspace in order to reach the complicated path. In short, can one robot manipulator reach the point precisely in it’s workspace by a given pose command? What about another same type manipulator? Can it reach the same point precisely without one more “teach and learn” process? In this paper, we will introduce the serial calibration method for improving the accuracy of pose of the robot manipulator. Using laser tracker as one high accuracy tool for measuring and calibration. Finally, we compare the parameters before and after the calibration in the experiment and show the calibration result.