CAN BUS 網路之鋼板熱軋溫度監控系統

Hot Rolling Mill Temperature Control System Based on CAN BUS Real Time Network with Rapid Control Prototyping Technique

孫成啟(Cheng-Chi Sun)

指導教授 ： 陳傳生

元智大學/工程學院/機械工程學系/碩士(2003年)

摘要

鋼板熱軋的生產過程中，精軋區的溫度控制與量測的精確性，直接影響鋼板品質。溫度控制的原理為：將精軋區各點的實際資料，如溫度、灑水量等，輸入到熱傳模擬模型中，估算出下一點的溫度，進而控制軋延速度與冷卻水量，以達到控制鋼板厚度的目的。然而熱軋廠的生產線距離超過100公尺，主要量測點有三處以上，欲能同時量測各點的資料，並即時傳送到模擬電腦中，需要一個即時的通訊架構。
本論文經過一些網路通訊協定的比較，提出以CAN（Controller Area Network） bus作為熱軋溫度監控系統的網路通訊架構。使用CAN通訊協定中的Remote Transmit Request（RTR）作為同步觸發信號，由主模擬電腦間隔預設的取樣週期發出RTR信號，觸發同在CAN bus上的遠端站台的取樣工作，並立即傳回所量測的資料。全部的站台都採用硬體中斷的方式，處理信息接收與傳送，以縮短反應時間（latency）。
為達快速開發控制程式的目的，採用xPC Target作為控制雛型，透過Simulink/Real Time Workshop工具自行開發CAN bus通訊硬體驅動模組，包含初始化模組，設定CAN controller；傳送模組傳送信息；接收模組接收信息；傳送RTR模組傳送RTR信息以及FIFO Buffer模組暫存待傳送的多筆信息；中斷模組具有區分發生中斷的來源的能力。所有模組可以在xPC Target的即時環境底下運作，並且可供後續其他計畫使用。本控制系統的通訊架構與程式都經過實驗，檢證其適用性。實驗計有飽和傳送接收實驗，驗證大量資料傳輸；RTR中斷實驗，驗證RTR信息要求遠端站台傳送資料；多站台RTR實驗，驗證三個站台下RTR架構的性能。

關鍵字

熱軋 ； 溫度監控 ； 即時

並列摘要

In the hot rolling process, the performance of temperature control directly influences the quality of steel. The temperature control system receives readings from the finishing milling machines, such as temperature and the quantity of the spraying water at each station, and feed them into a thermal model to predict the temperature distribution along the length of a steel slab. From the predicted temperature distribution the temperature control system modifies the rolling speed and the quantity of cooling water to keep the thickness of steel within specifications. However, a typical hot rolling production line spans more than a hundred meters, with three measuring sites connected with a network to transmit measurements to a main control computer. This thesis proposes a new temperate control system framework based on the Controller Area Network (CAN) protocol, which can synchronize data acquisition with remote sites and become the infra-structure of a more complete hot rolling mill control system.
In the proposed temperature control system, the main control computer send a Remote Transmit Request (RTR) message frame defined in the CAN protocol as a synchronizing signal to trigger the data acquisition of all remote stations on the bus. Remote stations return readings to the main computer with different message ID. To reduce the latency, message transmission and reception are triggered by hardware interrupt from CAN controllers.
To reduce the development time, we applied rapid control prototyping techniques with tools like Simulink and Real Time Workshop. We developed our own device driver blocks for CAN bus interface card PCM3680 from Advantech in C code, which is not supported by the official product. The developed block library provides functions including hardware initialization, message transmission and reception, RTR function, interrupt service routine and FIFO Buffer push/pull blocks to expand the capacity of a generic interface card. These function blocks are executed in a xPC Target system. Future users can easily apply these blocks in a building block approach to create a new CAN control network. The performance of these blocks are thoroughly testified through numerous experiments including full data transmit to transmit and receive 128 bytes data, RTR interrupt to transmit RTR frame and get data back, and RTR interrupt in multi-node, the self-developed CAN bus modules has verified its usability on network and program.

並列關鍵字

hot rolling ； temperature control ； CAN ； real time

參考文獻

[1] 朱倉環, 「熱軋製程中精軋區溫度控制之研究」, 元智大學, 碩士論文, 民國87年10月.

[2] 王敏和, 「熱軋廠精軋區溫控系統之前饋與回饋控制器設計」, 元智大學, 碩士論文, 民國86年6月.

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