工业控制网络中几种介质访问方式的分析.doc

专业资料参考首选工业控制网络中几种介质访问方式的对比分析基于组合特征的车牌字符识别* 路小波凌小静刘斌张玉萍佟为明李辰(东南大学教育部智能运输系统工程研究中心哈尔滨工业大学电气工程与自动化学院,哈尔滨哈尔滨工业大学哈尔滨南京 215 00 01 96) 摘要本文阐述了应用于工业控制网络中应用的多种介质访问控制方式, 并对其中常用的几种常用介质访问控制方式的优缺点进行了分析,重点分析了载波监听多路访问、时分复用、令牌环及总线令牌等介质访问方式, 同时并给出了各种方式的应用实例。提出了基于 Zernike 矩和小波变换特征相结合的车牌字符识别方法。利用 Zernike 矩描述字符全局特征,小波变换系数描述字符细节特征,采用神经网络进行车牌字符分类。测试结果表明,这种组合了两种特征优点的方法实用有效,识别效果优于两种特征独立使用的情况。关键词工业控制网络车牌字符识别介质访问控制方式 Zernike 矩小波变换 CSMA 令牌中图分类号 TP336 文献标识码 A国家标准学科分类与代码 621. 特征提取中图分类号 TP2 文献标识码 A国家标准学科分类与代码 The Contrast Analysis of Several Medium Access Control Mode s in Industry works License Plate Character Recognition Based on bined Features Zhang Yuping Tong Weiming Li Chen Lu Xiaobo Ling Xiaojing Liu Bin ( School of Electrical Engineering and Automation, Harbin Institute of Technology, Harbin 150001, China ) ( Harbin Institute of Technology, Harbin 150001 Engineering Research Center for Intelligent Transportation Systems under Ministry of Education, Southeast University, Nanjing 210096 , China ) Abstract This paper introduces mon media access control mode s in industry works and analyses the advantages and disadvantages of them , respe ctively. . Especially Tt he difference of CSMA 、 TDMA 、 Token-R ing and Bus-Token is especially describ detail ed. And the application s of them are presented. This paper presents a method of license plate character recognition based on bination of Zernike moment and wavelet transformation features. The Zernike moment is used to describe the global feature of the characters, and the wavelet transform coefficient for the detailed feature of the characters. A work is used to classify the license plate characters. Experimental results show the presented method achieves better recognition accuracy than using two features separately. Key words industry works license plate character recognition MAC Zernike moment CSMA Token wavelet transform feature extraction 专业资料参考首选 1工业控制网络的特点引言引言工业控制网络是一种局域网, 但又不同于一般的局域网。因为工业控制网络必须满足工业现场的环境特点及控制的要求, 它具有自身的特点, 例如对于实时性、抗