發展先進運動控制之CAD及其於精密CNC之實現

Abstract

許多相當成功的控制理論紛紛問世，然而工業界的運動控制當中，大部份均停留於使用PID控制器階段，其不採用先進控制理論之原因眾多，其中之一乃為迄今無一橋樑聯絡學術與工業界之間的隔閡。本文提出一電腦輔助之控制器設計與模擬軟體CAD，透過低價位之定點DSP實現於CNC機台，完成精密運動控制，使控制系統具備良好的追跡能力、輪廓精度以及抗擾動能力。 前置控制器以改善控制系統的追跡性能。繼而為了對付各軸不一致的動態響應，加上交叉耦合控制器(cross coupled control, CCC)以降低其輪廓誤差。而為了確保所設計的控制器在實用上能有效降低模式誤差及外在負載等因素，進一步引入數位式擾動觀測器(digital disturbance observer, DDOB)。線性運動控制器固然有高的頻寬及穩健性，可在高速運轉下保有良好的運動精密度，但卻無法消除因為摩擦力所產生的非線性slip-stick現象，本文發展了摩擦力識別與補償器(nonlinear friction compensator, NFC)，將非線性的誤差進一步消除。 計之CAD軟體包含三個線性控制器及一個非線性摩擦力補償器之設計，並與德州儀器公司之Code Composer Stuido結合，自動產生DSP TMS320F2812控制器函式實現在DYNA MYTE 1007 CNC工具機上，實驗結果指出其精密度遠勝過一般工業用控制器，工具機輪廓誤差能有效的由原有的18.2μm達到4μm的精密運動控制效能。

Although many modern control algorithms were proposed recently, manufacturing still prefers the PID control because of its easy and reliable applications. In this thesis, a user-friendly computer aided design (CAD) software for advanced motion control is proposed and the DSP code is automatically generated for computerized numerical control (CNC) machine tools to achieve both tracking and contouring accuracy against external disturbance and mechanical friction. The feedforward controller is adopted to improve tracking performance and the cross-coupling control (CCC) is employed to cope with the contouring error. Moreover, the digital disturbance observer (DDOB) is included to decrease the modeling error and the effect of external disturbance. However, the slip-stick and quadrant glitches phenomena still cannot be successfully eliminated by applying the linear controllers. Therefore, a non-linear frictional compensator (NFC) is developed in this thesis to effectively reduce the contouring error caused by friction. In this thesis, the present CAD software includes controller design and simulation of three linear controllers and one non-linear frictional compensator. The code of Texas Instrument TMS320F2812 DSP microcontroller is automatically generated by the developed CAD to implement the control algorithms. Experimental results of a DYNA MYTE 1007 CNC machine indicate that both tracking and contouring errors are significantly reduced by applying the present advanced motion control design.