【作者】 黄硕；

【导师】 关新平；

【作者基本信息】 燕山大学 ， 控制理论与控制工程， 2006， 硕士

【摘要】 所谓网络化控制系统,就是指通过计算机网络和总线将传感器、执行器和控制器单元作为网络节点连接起来共同完成控制任务的闭环反馈控制系统。随着计算机网络的广泛使用和网络技术的不断发展,控制系统的结构正在发生变化。使用专用或公用计算机网络代替传统控制系统中的点对点结构,实现传感器、控制器和执行器等系统组件之间的控制信息可以相互传递的系统,即网络化控制系统的研究正在迅速成为当前国际控制领域的一个前沿课题,具有重要的理论意义和广阔的应用前景。它与传统的控制系统最大的区别在于:在网络控制系统中,网络通讯将成为控制系统的一个重要环节。由于网络传输中存在传输时延,并且这些时延通常具有不确定性和时变性,另外还存在传输数据时序的错乱和丢失等现象,这些都使得系统不再具有定常性和确定性。上述两个方面对控制理论的研究提出了新的挑战和发展机遇。本文系统的分析了网络控制系统的特性,网络的随机时延特性及网络数据包丢失特性等,分析了这些特性对系统控制性能的影响,提出了新的设计方法,解决了网络诱导时延、数据包丢失等现象给控制系统带来的稳定性和鲁棒性问题。首先对于时延小于一个采样周期且系统参数不确定情况下的线性连续系统,利用李亚普诺夫定理来估计传输时延的最大界,给出了网络控制系统渐进稳定的充分条件。进一步,根据网络诱导时延的Markov特性,建立了网络控制系统的Markov跳变模型,根据线性跳变理论分析了系统的稳定性,给出了状态反馈控制器的设计方法。通过仿真实例验证了每一种方法的有效性。其次,考虑了在整个网络传输过程中发生数据包丢失时,网络控制系统的稳定性问题。根据网络传输中数据包丢失的Markov特性,建立了网络控制系统的Markov跳变线性模型,根据李亚普诺夫稳定性理论,通过求解线性矩阵不等式,给出了系统稳定的条件。通过仿真实例验证了方法的有效性。更多还原

【Abstract】 The NCS is a feedback control system wherein the sensors, actuators andcontrollers as the network nodes connected through the computer network orfieldbus to accomplish the control tasks. With the rapid development,popularization and increasingly perfect of the computer networks technology,the control system based on the Networked Control System (NCS) has becomeone of the hot research task in current international control field. The researchon NCS has important theoretical meanings and also NCS has extensiveapplication prospects. Different from the traditional control systems, thedistinct characteristic of NCS is that the network communication is one of theimportant parts of the control system. Because of the network-induced timedelay which is often uncertain and time-varying, and the transmitted data erroror data dropout, the NCS is no longer a constant, maturity and certainty. Alsobecause of the event-driven and time-driven coexisted in NCS, so it is requirednew views and more sustaining theories to the study on NCS, which bringsforward newly challenge and development opportunity to the investigation ofthe control theory.This thesis systematically analyzes the characteristics of networkedcontrol system, network-induced time delays and network data packet dropoutetc, and the effects made onto the control performances, then propose newlydesigned methods which solve the stability and robustness problems of thecontrol system brought by the network-induced time delays and the data packetdropout.Firstly, in terms of the network-induced time delays, we consider the NCSdesign problem with the delays less than one sample period (which can becalled short delays). Based on the network-induced delays’ Markovcharacteristics, we propose the NCS Markov jump models, present thesufficient conditions for the stability of the NCS, and give the state feedbackcontroller design methods. Furthermore, considering the linear continuoussystem with the short delays and the uncertain parameters, estimating the maxbound of the transmission delays by Lyapunov theory, and the systemsasympotic stability condition is given. Also the simulation examples are givento illustrate the effectiveness of the proposed methods.Secondly, considering the NCS stability problem when data-packetsdropout happening during the whole transmission route. Based on thedata-packets dropout’ Markov characteristics, we propose the NCS Markovjump models, then get the system stability condition by Lyapunov stabilitytheory and LMI. Also the simulation examples are given to illustrate theeffectiveness of the proposed methods.Finally, network data packet dropout is another issue in NCS, which candegrade the system’s performance and even can make the system instable. Soas for the NCS with data packet dropout and network-induced time delays, thispaper proposes a new modeling method. According to the controller updateinformation when the data packet lost, two different schemes are given: one isadopting the latest arrival data information at the previous sample time toupdate the controller, another is designing a data packet dropout compensator,using the compensator’s data information to update the controller. In theproblem analysis, we set up the model of the Asynchronours dynamical systemwith data-packet dropouts. Based on the Lyapunov stability theory, we presentthe sufficient conditions for the stability of the two different closed NCSmodels, respectively. Also simulation examples are given to illustrate thevalidity of the results.更多还原