离散事件触发通信机制下 NCS 实验平台的构建

摘要

目前离散事件触发通信机制 DETCS（Periodic time-triggered communication scheme）下 NCS（Networked control system）理论研究结果的验证仍限于单机下的 Matlab 仿真，尚无真实网络环境的引入；而传统基于周期时间触发通信机制的 NCS 实验平台，又缺少受控制需求驱动事件触发条件的约束。针对此问题，开发了 DETCS 下的虚拟 NCS 实验平台。该平台以校园局域网为通信媒介，采用 OPC 通信协议，结合西门子 S7-300PLC，首先实现了分离于2台 PC 机上的被控对象和控制器的通信；其次将离散事件触发条件引入被控对象输出端，借助 Matlab OPC 工具箱提供的 OPC 技术及软件组态方法实现了真实网络环境下基于 DETCS 的虚拟 NCS 平台的搭建。实验平台测试及结果分析表明，DETCS 的引入兼顾了 NCS 的控制性能和网络资源的节约，所搭建的平台能够为 DETCS下的 NCS 理论研究提供有效的工程可用性验证平台。%The verification of theoretical results of NCS based on discrete event-triggered communication scheme (DETCS)is still in a Matlab simulation environment which uses a single computer without introducing the real network environment,and the traditional NCS experiment platform under the periodic time-triggered communication scheme lacks the event-triggered condition constraints driven by control requirement.In view of this,we developed the experiment platform of virtual NCS under DETCS.On the platform,a campus LAN is selected as the communication medium,meanwhile,OPC communication protocol is adopted in combination with Siemens S7-300PLC,the platform first realises the communication between the plant and controller which is separated from two computers;Then,it introduces the discrete event-triggered condition into the plant output,furthermore,in virtue of the OPC technology,which is provided by Matlab OPC Toolbox,and the software configuration method,it realises the construction of virtual NCS platform based on DETCS under real network environment. Experiment platform test and results analysis showed that the introduction of DETCS could take the control performance of NCS and the saving of network resource into consideration simultaneously,and the constructed platform could provide effective engineering availability verification platform for theoretical research of NCS under DETCS.