以快速開關閥實現主動式氣壓隔振桌系統定位控制之研究

Abstract

本文旨在發展主動式PWM氣壓隔振桌系統之定位控制，以PWM控制訊號配合並聯式雙快速電磁開關閥，實現主動式氣壓隔振桌之位置控制。隔振桌腳座內的氣墊式氣壓隔振器，原為被動式的氣壓隔振元件，本文利用其充氣加壓過程中產生的膨脹與收縮的變化特性，作為主動定位控制下的單動式氣壓致動器。四個腳座皆有獨立的位置閉迴路迴授控制，可獨立進行位置控制。 本文以軟體實現脈波寬度調變，並產生PWM控制訊號控制電磁開關閥開啟與關閉時間，如此可不必透過額外的硬體電路實現脈波寬度調變，並且快速開關閥亦具有較比例伺服閥廉價之優勢，使得系統可以在較低成本的同時亦可達到控制精度的要求。 本文首先嘗試建立單一腳座氣壓隔振器之非線性數學模式，使系統簡化為一三階非線性時變系統，再結合具 追蹤性能之以函數近似法為基礎適應性滑動控制（FSB-ASMC+H infinity, Fourier series-based Adaptive Sliding Mode Control with H-infinity tracking performance）進行控制器的設計，藉以克服氣壓系統之高度不確定性與時變問題。在實驗前以MATLAB軟體進行系統的動態模擬，藉以驗證系統架構與控制器的可行性。最後建立實驗系統進行即時的控制實驗，包含空載以及承載桌面下的定位與軌跡追蹤控制，並加入一主-從(Master-slave)同步控制方法進行比較，藉以驗證此控制器對於各個腳座內的氣壓隔振器皆可達到良好的定位與軌跡追蹤效果。

This study aims to develop the position control of an active PWM (Pulse Width Modulation)-controlled pneumatic isolation table system. A novel concept using parallel dual-on/off valves with PWM control signals is implemented to realize active control and to improve the conventional pneumatic isolation table that supported by four pneumatic cushion isolators. In this study, the cushion isolators are not only passive vibration isolation devices, but also pneumatic actuators in active position control. Four independent closed-loop position feedback control system are designed and implemented for the four axial isolators. In this study, on/off valves are used, and PWM is realized by software. Therefore, additional hardware circuit is not required to implement PWM and not only cost down but also reach control precision of demand. The study first derives the nonlinear time-variant mathematical models of single-axial pneumatic isolation system and then simplifies the models as a 3rd system. In the controller design, the Fourier series-based adaptive sliding-mode controller with H-infinity tracking performance is used to deal with the uncertainty and time-varying problems of pneumatic system. The open-loop and closed-loop dynamic simulations are implemented by MATLAB to verify the feasibility of the proposed system and controller. Finally, the experiments on the pneumatic isolation table system for synchronous position and trajectory tracking control, including no-load and loading conditions, and synchronous position control with master-slave method are implemented in order to verify that the controller for each cushion isolator can realize good position and trajectory tracking performance.