【作者】 黄海；

【导师】 王树青；

【作者基本信息】 浙江大学 ， 控制科学与工程， 2007， 博士

【摘要】 网络控制系统是指建立在数字总线基础之上的控制系统。随着现场总线控制的推广应用，网络控制这一融合最新通信网络技术的计算机控制技术已越来越引起人们的广泛关注。与传统的点对点控制系统相比，网络控制系统具有可靠性高、系统连线少、结构灵活、通信协议开放等诸多优点。然而，由于控制网络采用串行数字通信方式，各节点将按照协议规范共享网络通信资源，从而不可避免将把网络环境中诸多不确定因素引入控制系统。如何在网络环境下，充分考虑网络时延等对控制系统的影响，是进行网络控制系统分析与设计的关键。网络控制本质上是一种应用技术研究，网络控制算法设计应立足于对原有成熟控制算法进行针对网络环境的适应性修改和补充。为此，本文以网络技术在控制系统设计中的实际应用为出发点，探讨建立在数据网络基础上的控制系统设计理念，设计并开发了基于以太网的网络化运动控制实验平台，研究基于网络的控制系统设计方法，并进行了实物验证。论文的主要内容包括：1．在深入研究网络环境下时延的组成与产生机理基础上，指出回路总时延是网络控制系统设计考虑的重点。针对回路总时延表现为单周期和多周期两类特性下，讨论网络控制系统与经典计算机采样控制系统之间的相似之处与区别，定性指出在网络时延单周期情况下，二者基本一致，而在网络时延多周期情况下，采样周期的多频切换使网络控制系统表现为不同采样控制系统间的跳变，而这种切换过程是导致网络控制系统不稳定的重要原因。2．由于实验平台在网络控制系统研究中具有非常重要的现实意义，因此本文设计实现了一个基于以太网的网络化运动控制实验平台(Ethernet Networked Motion Control Open Platform)。系统选用电机速度伺服控制系统作为网络控制的目标对象，采用高性能数字信号处理器设计实现了内含以太网接口的电机驱动器网络化节点；设计了可方便实现各种控制算法的基于PC机的网络控制器；设计了网络流量干扰节点，可对网络拥塞程度实现定性控制；设计实现了图形化网络数据监视系统，动态显示控制系统状态曲线。该实验平台可真实展现出网络控制系统的实际问题，为网络控制的算法研究创建了一个良好的实验环境。3．针对网络控制系统中数据传输的多周期时延问题，提出了一种在不改变现有基于模型的极点配置控制方法框架的前提下，通过预设网络时延，计算出一组待选控制输出序列，在执行器端附加数据选择器，根据控制回路实测时延，选择对应控制输出量的控制策略。通过与PID等算法在不同网络拥堵环境下的实验对比表明，该方法可在一定程度上解决网络不确定时延问题。4．通过对网络控制系统数据更新过程的深化认识，提出了一种网络环境下的模型预测控制改进算法，利用预测控制理论在控制时域内的滚动优化作用，计算得到优化控制序列矩阵，通过优化控制序列来改善系统在拥堵环境下的控制效果，能够较好地解决网络环境的多周期时延问题。通过在网络实验平台实际环境下的实验结果验证了该方法的有效性。5．通过对网络控制系统特征的分析，阐明了工业IT是工业控制系统设计未来发展的方向，提出了基于网络数据传输建立工业控制虚拟回路的思想，建立了复杂网络控制系统的多智能体模型，并采用合同网技术来解决底层控制层的计算任务调度问题。最后，在总结全文工作的基础上，提出了有待进一步研究的课题和今后的工作重点。更多还原

【Abstract】 A great deal of attention has recently been focused on the networked control systems (NCSs) which are based on communication network. With the spread and application of the field bus control system, networked control systems have being given rise to the engineers’ concern. Compared with the traditional point to point control systems, networked control systems which are framed on field bus have a lot of advantages such as high reliability, little system wiring, flexible configuration, open communication protocol, realizable information resource sharing, etc. However, the control systems communicate in serial digital line, causing nodes competing for network resources by protocol. Then some uncertainty from network environment will be brought into the control systems inevitably. The key to networked control systems analysis and design will be how to handle the issue caused by network time delay in network environment. Essentially, networked control is an application technology. That’s why network control algorithm design should be established in modification and complement of originally developed control algorithm to adapt to the network environment. Accordingly, this paper investigates the control system theory on data network, develops Ethernet Networked Motion Control Open Platform (ENMCOP), establishes methodology on control system design based on network and gets validation on practical experiment of networked control systems.The main contributions in the paper are as following:1. Investigating time delay composition and production mechanism in network environment, the thesis points out loop delay is the focus of network control system design. Extensive discussion is given on the similarity and difference between networked control and traditional computer sample control while loop delay have characteristics as single sample period and multiple sample periods, then qualitative conclusion is drawn that in single sample periodmode NCSs act almost the same as the computer sample control systems; otherwise, in the case of multiple sample periods network delay, multi-frequency switch of sample periods is the important factor causing unstable of the network control systems.2. Considering the significant practical meaning of experimental platform for network control system research, the author implements an Ethernet Networked Motion Control Open Platform, which includes a speed servo motor driver as a net node with embedded Ethernet interface using digital signal processor; a network controller based on PC which is convenient for realizing sorts of control algorithm; network flow disturbers, helping control on network congestion; a visual graphical monitor system on real time network data, displaying control system state curve dynamically. This experimental platform exhibits real problems on network system, and offers a nice experimental environment for network control theoretical research.3. To fix the problem of multiple sample periods during data transfer in network control systems, the paper puts forward a proposal that presumes network time delay and calculates a set of selectable control output sequences without changing the current model based pole assignment control scheme, attaches data selector to the actuator, selects corresponding control output as per real loop time delay. Compared with PID applied in network congestion experiment in different environment, this control algorithm can help to solve the network uncertain time delay problem to a certain extent.4. With deep understanding on data update process of network control system, the thesis brings forward an improved algorithm of networked model predictive control, takes advantage of scroll optimization in control horizon to get optimized control sequences matrix and to improve system control effect while network being congested, which solves multiple sample periods time delay problem of network in a better way. Also, this has been demonstrated byexperimental results in the ENMCOP.5. The relationship between the networked control systems and the industrial IT is illustrated, and the idea is provided to construct virtual loop in the industry control system design based on the network data transfer. A design pattern of complex networked control systems using multi-agent-system model is proposed and the task scheduling problem is resolved based on the contract net technology.Finally, a summary is made on some remaining challenges and research emphases in the next phase.更多还原