隨著工業的進展，製造業目前已處於時間與品質並重的時代，因此目前自動化製造設備一直朝向高速高精度的方向發展。本論文就針對CNC工具機在循圓時，減少其追蹤誤差。摩擦力的影響是一般機械系統中主要的非線性因素來源，所以系統於低速度運作時，首先要克服的就是不同物體接觸面所產生的摩擦。摩擦是非常複雜的非線性物理現象，包括靜摩擦、庫倫摩擦及黏滯摩擦，其中靜摩擦與庫倫摩擦屬於非線性函數。以雙軸XY平台畫圓時，在每90度區間附近會有其中一軸的速度正好穿越零點，亦即平台反轉的時候，因摩擦力的影響而產生的突波，此種問題稱之為「quadrant glitches」。 象限誤差主要是因為摩擦力帶來的暫態現象。因此，我們為了解決這個暫態現象問題。我們會預先補償一個值在軸要換象的時候，讓這系統迅速到達穩態。讓系統一直維持在穩態。我們會在工具機循圓前，從系統的動態觀察以求得補償值。 另外，我們又設計前饋控制器和比例控制器。希望此控制器改善其系統的追蹤性能。 最後，關於以上循圓時的伺服控制在CNC工具機上，都有經過實驗，以證明這些方法的可行性。 As the development in industry, time and quality are more and more important in manufacturing industry. Therefore, automatic manufacturing machines are tending to high speed and high precision. This thesis is aimed to eliminate tracking error of traveling a circular profile on the CNC machine tools. Friction is one of the most significant source of nonlinear disturbance for the motion control which caused by the relative motion of different contact surface at the low velocity. The nonlinear component of friction such as static friction (stiction) and the Coulomb friction should be overcome so that the tracking error will be eliminated. When the X-Y tables are tracking a circular profile, quadrant glitches appear at ninety degrees intervals, i.e. the motion of one axis has a zero velocity crossing and reverses direction. The quadrant glitches were due to friction brought about transient phenomenon. Therefore, we will solve the transient phenomenon. We will make the system to reach steady state quickly, we may anticipate compensating a value when the motion of one axis has a zero velocity crossing and reverses direction. We will observe the system dynamic before traversing a circular profile, and to obtain a compensated value on off-line. In addition, we designed the feedforward and P feedback tracking controllers. The research adopts feedforward controller to improve the tracking performance of the system. Finally, the above servo loop control of tracking a circular profile on CNC machine tools is verified by the simulation and experimental results.
