LuGre摩擦力模型於CNC高速微動之精密控制設計與調整

Abstract

在3C產業之電路板啄鑽加工中，實現高速精密之微動控制設計，面對的主要問題有伺服馬達控制設計、與機台整合之摩擦力，以及擾動之克服。啄鑽動作為高頻、高速往復的微動控制，因為命令甚小，受摩擦力影響相對變大，影響加工精度，因此本論文以卡爾曼濾波器抑制CNC伺服馬達之電流回授雜訊、擾動觀測器抑制外界擾動，以提升伺服馬達的剛性，最後考慮摩擦力的動態特性，採用LuGre動態摩擦力補償器，但因為動態摩擦力的三個模型參數，在鑑別上有一定困難度存在，在此以off-line的方法，能快速正確的分別鑑別出穩態非線性摩擦力NFC與動態摩擦力LuGre模型參數。本論文在CNC機台上進行啄鑽動作之實驗，加入整合P、DOB、LuGre摩擦力模型之控制器，使得位置響應追跡誤差之方均根(RMS)值從90.12um大幅度改善至2.89um，有效的克服CNC機台上非線性摩擦力。

In the pecking machining process for 3C industry electronics board, the major concerns are the servo motor control design, the friction compensation of the machine, and suppression of the external disturbance. Because the micro-motion command of a pecking process is in a high frequency and high-speed repetitive motion, the effect of friction to motion error thus becomes relatively more dominant. This Thesis applies the Kalman filter to suppress the noise of the current feedback in CNC servo motors. Moreover, the disturbance observer (DOB) was applied to the CNC servo motor control to reduce the effect of external disturbance. Then, both the nonlinear static and dynamic friction models will be considered to improve pecking motion precision. By concerning the dynamics of the friction, the LuGre friction model is adopted in this study. However, the three estimated coefficients of the LuGre model are difficult to obtain and an off-line approach is proposed to obtain those coefficients of friction model. Finally, the developed controller including the P, DOB, and LuGre models were integrated on a CNC machine. Experimental results of a pecking process indicate that the RMS of the tracking error is significantly reduced from 90.12um to 2.89um by applying the proposed control structure.