Abstract
傳統上切削自由曲面的工件使用三軸加工機, 但是耗時過多, 使用五軸加工能減少加工自由曲面工件所需時間, 本論文研究電腦數值控制加工的軌跡精度誤差, 也推導五軸數值控制時所需的機構轉換方程式。此外本論文運用前饋控制方法來改善軌跡精度; 前饋控制利用系統鑑別而得的已知資訊, 扭曲各軸應走位置, 使其經傳統控制後, 各軸的實走位置恰可等於扭曲前各軸應走位置。因五軸切削時多為曲線, 因此滯後誤差不可避免的造成軌跡誤差, 經實驗以雙軸走圓的方式來測試前饋控制的效果, 發現滯後誤差降為原來得 1/30~1/50時軌跡誤差約為原來的2/3~1/2。Conventionally cutting a free-form surface workpiece needs a3-axis milling machine, but too much time is spent, thus 5-axis milling machines are used to reduce the time needed in themachining process. This thesis is dedicated to investigate thecontouring errors in CNC maching process, by the way the tran-sformation equations needed for 5-axis CNC is also derived.Besides, this thesis applies feedforward control to improve thecontouring performance. Feedforward control uses the systemimformation obtained by identification process to distort thesetting value so that the actual value will the same as thesetting value. Because most of the paths produced in 5 axis CNCmachining are curves, following errors will produce contouringerrors,through our experiments of going circle paths, followingerror is reduced to 1/30 to 1/50 of the original, andcontouring error is reduced to 2/3 to 1/2 of the original.