二維平面式步進馬達之運動控制

Abstract

針對高速、高精度的運動控制，本文介紹一種強健的控制器結構。整個控制器的結構包含了以下幾個部分：速度迴路中的擾動觀測器、位置迴路中的PD回饋控制器與重複性控制器、及以零相位誤差追蹤控制器作為系統的前饋控制器。首先，針對馬達本身的參數不確定性及外界對系統的擾動影響，本文在系統的速度迴路中使用了擾動觀測器進行擾動因素的排除。接著在位置迴路中以PD控制器以建構一漸進穩定的閉迴路回授控制系統。然而在此時卻發現擾動觀測器並無法完全將馬達十分高頻的阻滯力部分予以排除，而這無法完全由擾動觀測器所排除的阻滯力部分使得系統產生顫震的現象，又此阻滯力可視為一週期性的擾動，因此在位置迴路中再加入重複性控制器以加強對擾動抑制的效能。接著為了提昇高速、高精度的定位及軌跡追蹤的性能，在閉迴路回授控制系統前加入零相位誤差追蹤控制器作為系統的前饋控制器。由速度迴路之擾動觀測器及位置迴路中的重複性控制器提供系統對擾動因素的強健性，以位置迴路中的回饋控制器獲得一漸進穩定的系統，再由前饋控制器提昇整個系統軌跡追蹤的性能。最後由模擬的結果說明以上各種控制器的效果。

In this thesis, a robust control structure for high-speed/high-accuracy motion control of two-dimensional stepping motor is designed. The overall control system consists of the following elements: a disturbance observer in the velocity loop, a PD feedback controller and a repetitive controller in the position loop and a ZPETC based feedforward controller. To attenuate disturbances and system uncertainties, a disturbance observer is utilized in the velocity loop. A PD controller is used in the position loop to construct an asymptotically stable system. However, the high-frequency cogging forces generated during the motion of the planar motor can not be rejected effectively by the disturbance observer. This causes a chattering phenomenon. Since cogging forces can be viewed periodic disturbances, a repetitive controller is designed in the position loop to enhance the performance of disturbance rejection. Then for the sake of the motion control of high-speed/high-accuracy positioning/tracking, a ZPETC is added to the closed-loop feedback control system. The disturbance observer in the velocity loop and the repetitive controller in the position loop maintain the system robustness to the external disturbances and model uncertainties, and the ZPECT feedforward controller significantly improves the tracking performance. Finally simulations are conducted to show the effectiveness of the robust control structures.