【作者】 梁瑾；

【导师】 吴爱国；

【作者基本信息】 天津大学 ， 控制理论与控制工程， 2004， 硕士

【摘要】 中 文 摘 要在工业控制领域中，随着控制系统规模的不断增大，集中控制系统已经不能满足要求，控制网络已经广泛应用到工业控制中。现场总线就是顺应这一形式发展起来的技术，并在一定程度上解决了这一问题。但是，现场总线的开放性是有条件的，是不彻底的。当现场总线的发展遇到阻碍时，以太网技术却得到了迅猛发展。如果能将以太网技术成功地用于工业控制底层网络，就可以打破传统的工业控制网络体系，实现办公自动化与工业自动化的无缝结合。将以太网应用于网络控制系统具有许多优势，但同时也存在一定问题，主要包括传输的不确定性、以太网的可靠性问题以及缺乏统一的应用层协议。本课题主要从两个方面对基于以太网的网络控制系统进行研究。首先是关于应用层协议方面：研究实现当前应用最为广泛的 Modbus/TCP 协议，并通过网络测试程序检验了实现的正确性。其次针对基于以太网的网络控制系统具有不确定时延的特性，提出了将广义预测控制应用于网络控制系统的思想。同时，为了克服建模误差和系统不确定性影响，采用 BP 结构神经网络对系统进行误差补偿，进一步改善控制品质。最后，本文设计了基于以太网的网络控制系统，将 Modbus/TCP 协议嵌入客户机和服务器程序中，进行了仿真实验研究。通过比较普通的 GPC 和基于神经网络误差补偿 GPC 的系统响应曲线，表明了此控制方法的有效性。更多还原

【Abstract】 ABSTRACT With the unceasingly expanding of the scale of industrial control system,central control strategy has been unable to meet the relative control demand.Networked control system has been widely applied in industrial control. Field bus is atechnology to meet this demand. It solves this problem in a certain sense. But fieldbus is not thoroughly open. When the development of field bus runs into impediment,Ethernet develops rapidly. If Ethernet can be implied in factory floor networksuccessfully, we can break the traditional structure of control system and realize theseamless integration of office automation and industrial automation. The application of Ethernet in network control system (NCS) has manyadvantages, but it also bring some problems, including the transmission indeterminacy,the reliability of Ethernet and the lack of unified application layer protocol. The paper researches network control system based on Ethernet from twoaspects. First, the paper studies and implements the Modbus/TCP application layerprotocol, which is widely used in Industrial Ethernet. In addition a network testprogram named CIP Alyze3.0 is used to analyze the accomplished communicationprogram. Secondly, with regards to the characteristics of uncertain delay of networkedcontrol system, this paper puts forward an idea of using Generalized PredictiveControl (GPC) in the networked control system. To overcome the influence ofmodeling error and uncertainty of a system, we compensate error of the system byadopting BP neural network. The paper last designs an NCS based on Ethernet and embeds Modbus/TCPprotocol in client program and server program. In the experimental research, theresponse curves of the traditional GPC controller and the improved GPC controllerare compared. The result shows the effectiveness of the scheme.更多还原