以PLC為基礎之離散事件系統程序控制器與錯誤診斷系統設計

Abstract

本論文以PLC為基礎，提出一套離散事件系統之程序控制器與錯誤診斷系統的整合性設計策略。 由於自動化製造系統的日益複雜，能夠達成有效處理高階控制系統與低階實現的設計工具，是一個格外重要的需求。我們提出一套整合(1) IDEF (Integrated CAM definition)，(2) PNC (Petri net controller)，(3) TPL (token passing logic)與(4) LLD (ladder logic diagram)四種工具的IDEF/PNC/TPL/LLD (IPTL)方法，有系統化地設計與實現控制器。首先利用IDEF技術來做系統的功能分析與控制流程的靜態設計，然後轉換為裴氏網路控制器PNC模式來做系統之動態模擬驗證，再結合TPL技術，可以設計出符合IEC 1131-3標準的階梯邏輯圖LLD，在PLC上來實現。 為了改善系統之可靠度與安全性，我們進一步提出的錯誤偵測器可以即時偵測出(1)程序錯誤，(2)感測器錯誤，與(3)致動器錯誤，並且將偵測錯誤的邏輯函數轉換為階梯圖，以PLC為基礎來實現錯誤診斷。而錯誤循跡器的設計，則是提供維修工程師在故障發生後，循跡由程序控制階梯圖所推衍的AND/OR Tree來有效地找尋發生錯誤裝置的輔助工具。因此，本論文完成了一個將程序控制及錯誤診斷系統以PLC之階梯圖實現出來的有效設計方法。

In this thesis, an integrated approach for the PLC-based sequence controller and the fault diagnostic system design in discrete event system (DES) is proposed. Since automated manufacturing systems become more complex, the need for an effective design tool to achieve both high-level control systems and their low-level implementations becomes increasingly more important. The IPTL (IDEF/PNC/TPL/LLD) method is presented to integrate the IDEF (Integrated CAM definition), PNC (Petri net controller), TPL (token passing logic), and LLD (ladder logic diagrams) tools to obtain the ladder diagram for the PLC implementation systematically. In the proposed IPTL design, the system function and the control flow are designed with static analysis by using the IDEF technique and it transforms the control flow model into the PNC model to verify its dynamic behavior. The conversion of the PNC into the IEC-1131-3 LLD on a PLC is then followed by applying the TPL concept. For improvement of reliability and safety of systems, a fault detector is proposed and implemented on a PLC by converting the logical functions of fault detection into an LLD format. The proposed PLC-based fault detector detects all the sequence faults, sensor faults, and actuator faults. Furthermore, a fault tracer supports the presented fault diagnosis to traverse the AND/OR tree which is derived from the LLD of the sequence controller.