一类介质访问约束下的网络控制系统设计

针对多输入多输出的网络控制系统,传感器和执行器为时间驱动,由于网络资源的有限性,在每个传输周期内,系统往往只有部分传感器和执行器得到网络介质访问权,与远程控制器进行数据传输,这称为网络控制系统的介质访问约束性,它极大地影响到系统的稳定性和控制性能,成为网络控制中亟待解决的问题。针对这一问题将网络控制系统建模为输出矩阵和输入矩阵随介质约束改变的切换系统,并利用切换系统分析方法和稳定性理论,设计了切换观测器和基于观测器的状态反馈控制器,分析了周期调度下该网络控制闭环系统的稳定性,最后通过仿真验证了这种方法的有效性。     

具有数据包丢失的网络控制系统的估计问题

主要考虑了具有数据包丢失的网络控制系统(NCSs)的估计问题。首先,给出经典的卡尔曼滤波估计器和协方差矩阵。当量测方程带有噪声时,通过递推的方法严格推导出最优估计(条件期望)。另外,根据系统丢包行为能否被观测到的估计问题,分情况进行讨论。最后,在实际应用中开发了一个次优的近似估计器。这对在大的有限域下研究具有数据包丢失的网络控制系统有所帮助,也为进一步分析网络控制系统的问题提供了研究方向。     

Packet-loss-dependent stabilization of NCSs with network-induced delay and packet dropout

This paper is concerned with controller design of networked control systems (NCSs) with both network-induced delay and arbitrary packet dropout.By using a packet-loss-dependent Lyapunov function,suffic...     

Optimal Output Feedback Control and Stabilization for NCSs with Packet Dropout and Delay: TCP Case

This paper considers the output feedback control and stabilization problems for network control systems (NCSs) with packet dropout and input delay, and the TCP (transmission control protocol) case is mainly investigated. Specifically, whether the control signal is lost can be acknowledged by the receiver in the NCSs. The main contributions are: 1) For the finite horizon case, the “optimal” output feedback control is derived by using the dynamic programming approach, and it is noted that the separation principle holds for the considered situation; 2) For the infinite horizon case, for the first time, the necessary and sufficient stabilization conditions are derived for NCSs with packet dropout and delay.     

网络控制系统实时仿真平台的设计与开发

网络控制系统(NCSs)是通过通信网络实现控制系统单元信息交换的分布式控制系统.由于通信网络的引入,有可能使控制系统的性能降低甚至导致系统不稳定,这些不利因素使得对网络控制系统的分析研究变得更为复杂.利用混合编程技术并搭建基于实时通信网络的仿真平台,可为网络控制系统提供有利的分析工具.最后以状态反馈控制器为仿真实例,证明该研究平台的优势及有效性.     

Stability Analysis of Event-Triggered Networked Control Systems with Time-Varying Delay and Packet Loss

Networked control systems(NCSs) are facing a great challenge from the limitation of network communication resources. Event-triggered control(ETC) is often used to reduce the amount of communication while still keeping a satisfactory performance of the system, by transmitting the measurements only when an event-triggered condition is satisfied. However, some network-induced problems would happen inevitably, such as communication delay and packet loss, which can degrade the control performance significantly and can even lead to instability. In this paper, a periodic eventtriggered NCS considering both time-varying delay and packet loss is studied. The system is discretized into a piecewise linear system with uncertainty. Then the model is handled by a polytopic overapproximation method to be more suitable for stability analysis. Finally, stability conditions are obtained and presented in terms of linear matrix inequalities(LMIs). The result is illustrated by a numerical example.     

一种面向分布式仿真的网络通信构件

通过对仿真数据划分为控制信息和状态信息，提出了运用RTP/RTCP协议进行仿真数据进行传输。为了提高仿真数据传输与处理的性能，分析和讨论了数据缓冲队列、数据包的组装与校验和网络异常检测等关键问题。结合面向对象的框架技术，运用多线程技术，分别设计和实现出了客户端和服务器端的网络通信构件。通过在某分布式空中交通管制系统仿真平台的实际应用表明，该网络通信构件能够满足分布式仿真的应用需求，并且还具备了可重用性、可扩展性和易用性等特点。     

Graphic theory on interval stability of networked control systems

A new method on the interval stability of networked control systems （NCSs） with random delay and data packet dropout is studied. Combining interval systems and NCSs, a graphic condition on judging interval stability is presented in terms of the weighted diagraph theory in graph theory. Furthermore, utilizing the graph-theoretic algorithm, the delay-depended controller gains are obtained. Aiming at the same delay and data packed dropout, several controller gains are obtained, simultaneously. The example and simulation illustrate the effectiveness of the proposed method.     

Robust H∞ control for networked control systems

The robust H∞ control for networked control systems with both stochastic network-induced delay and data packet dropout is studied.When data are transmitted over network,the stochastic data packet dropout process can be described by a two-state Markov chain.The networked control systems with stochastic network-induced delay and data packet dropout are modeled as a discrete time Markov jump linear system with two operation modes.The sufficient condition of robust H∞ control for networked control systems stabilized by state feedback controller is presented in terms of linear matrix inequality.The state feedback controller can be constructed via the solution of a set of linear matrix inequalities.An example is given to verify the effectiveness of the method proposed.     

Fault Detection for Uncertain Delta Operator Systems with Two-Channel Packet Dropouts via a Switched Systems Approach

This paper utilizes a switched systems approach to deal with the problem of fault detection(FD) for uncertain delta operator networked control systems(NCSs) with packet dropouts and timevarying delays. Uncertainties exist in the matrices of the systems and are norm-bounded time-varying.Two parts of packet dropouts are considered in this paper: From sensors to controllers, and from controllers to actuators. Two independent Bernoulli distributed white sequences are introduced to account for packet dropouts. Then an FD filter is designed under an arbitrary switching law. Furthermore, the sufficient conditions for the NCSs under consideration that are exponentially stable in the mean-square sense and satisfy H∞ performance are obtained in terms of linear matrix inequalities(LMIs), multiple Lyapunov functions(MLF) and average dwell-time(ADT) approach. The explicit expression of the desired filter parameters is given. Finally, a numerical example verifies the effectiveness of the proposed method.     

不确定网络化控制系统鲁棒故障检测

针对一类具有未知输入和模型不确定性的网络化控制系统,基于H_∞滤波器研究了系统的鲁棒故障检测问题.利用输入时滞方法,将含有网络传输时滞和数据丢包的不确定网络化控制系统建模成一类具有双加性状态时滞项的连续系统.采用Lyapunov-Krasovskii泛函方法分析了新系统的H_∞性能,并将所得结果应用于原系统鲁棒故障检测滤波器的设计,得到了滤波器存在的时滞依赖条件.最后,通过仿真验证了该方法的有效性.     

基于GASA算法的网络控制系统的控制器设计

提出了一种基于遗传算法和模拟退火算法的混合策略，用于单包传输下的线性网络控制系统中远程PID控制器的设计。这种新的混合策略被称为GASA算法。由于网络导致的延迟存在，GASA算法被用于确定最佳的PID增益。在求解过程中，GASA算法在各温度下依次进行GA和SA搜索，其中SA的初始解来自GA的进化结果，SA经过Metropolis抽样过程得到的解又成为了GA进一步进化的初始种群，而温度的更新由退温操作来控制。对设定的性能指标如超调量和调整时间的违背量将作为GAsA适应度函数中的惩罚项。本文对基于Profibus-DP网络的网络控制系统进行测试，并与修正Ziegler-Nichols法的优化结果进行比较，结果表明在对网络导致的延迟没有任何先验知识的情况下，用于网络控制系统中远程控制器设计的GASA算法能够获得满意的控制效果。     

Robust H∞ control for networked control systems

The robust H∞ control for networked control systems with both stochastic network-induced delay and data packet dropout is studied. When data are transmitted over network, the stochastic data packet dropout process can be described by a two-state Markov chain. The networked control systems with stochastic network-induced delay and data packet dropout are modeled as a discrete time Markov jump linear system with two operation modes. The sufficient condition of robust H∞ control for networked control systems stabilized by state feedback controller is presented in terms of linear matrix inequality. The state feedback controller can be constructed via the solution of a set of linear matrix inequalities. An example is given to verify the effectiveness of the method proposed.     

多输入多输出网络控制系统的绝对稳定性分析

考虑到网络诱导时延和网络通道的非线性反馈干扰,研究了多输入多输出网络控制系统的时滞依赖稳定性。基于各回路有界的状态反馈输入,建立闭环系统的Lurie时滞系统模型。应用Lyapunov稳定性理论和线性矩阵不等式工具,分析了各子系统在有扇形条件约束的绝对稳定性,同时得到网络控制系统全局稳定运行的最大允许时延界。最后,通过仿真例子,表明该方法是可行的。     

Mean-Square Stabilization of Networked Sampled-Data Systems with Packet Losses: Critical Sampling Intervals

This paper studies the stabilizing problem of networked sampled-data linear systems with independent and identically distribution(i.i.d.) packet dropouts. First of all, for the sampled-data system without packet losses, the necessary and sufficient conditions for the critical sampling intervals are given to ensure the mean square stability where zero order holder and generalized holder are adopted, respectively. Secondly, for the sampled-data system with i.i.d. packet losses, necessary and suffi...     

Observer-based H∞ control over packet dropping networks

A new controller design problem of networked control systems with packet dropping is proposed. Depending on the place that the observer is put in the system, the network control systems with packet dropping are modeled as stochastic systems with the random variables satisfying the Bernoulli random binary distribution. The observer-based controller is designed to stabilize the networked system in the sense of mean square, and the prescribed H∞ disturbance attenuation level is achieved. The controller design problem is formulated as the feasibility of the convex optimization problem, which can be solved by a linear matrix inequality (LMI) approach. Numerical examples illustrate the effectiveness of the proposed methods.     

基于SCFNN的网络控制系统远程控制器设计

提出将自组织模糊神经网络(SCFNN)应用于网络控制系统(NCS)中的远程控制器的设计。SCFNN的学习过程包托结构学习和参教学习两个阶段。结构学习的目的是对输入空间进行合理的模糊划分并动态地生成一组模糊逻辑控制规则，而参数学习是通过有监督梯度下降法来调整隶属度函数的参数以及模糊规则中结论部分的权值。最初的SCFNN只有输入节点和输出节点，而经过在线学习后逐步生成隶属度函数节点和规则节点。对基于Profibus-DP网络的网络控制系统进行测试，并与采用修正Ziegler-Niehols法设计的控制器的控制效果进行比较，结果表明基于SCFNN思想设计的远程控制器在网络控制系统中能够获得满意的控制效果。     

通信受限不确定Delta算子网络系统H∞滤波

研究了一类基于Delta算子的通信受限条件下参数不确定网络系统H∞滤波问题。在通信受限条件下,采用通信序列对网络控制系统进行分析,构建Delta算子描述的不确定系统滤波误差模型。利用线性矩阵不等式和Lyapunov-Krasovskii泛函提出滤波误差系统渐近稳定的充分条件,证明了系统的H∞性能,并给出滤波器的设计方法。数值仿真结果验证了所提方法的有效性。     

网络化控制系统的故障诊断

网络化控制系统与传统结构的控制系统相比具有许多优点,但经网络传输的控制信号所带来的随机时延、丢包、异步等问题会影响闭环控制系统的性能,因此需要发展可在网络环境工作的系统的控制理论和技术。故障诊断与容错控制对于控制工程实践特别是对安全性有严格要求的控制系统是十分重要的。近年来,我们较为系统地开展了网络化控制系统故障诊断与容错控制的研究工作从而可对故障诊断的主要研究结果进行概述。     

Observer-based H∞ control over packet dropping networks

A new controller design problem of networked control systems with packet dropping is proposed. Depending on the place that the observer is put in the system, the network control systems with packet dropping are modeled as stochastic systems with the random variables satisfying the Bernoulli random binary distribution. The observer-based controller is designed to stabilize the networked system in the sense of mean square, and the prescribed H∞ disturbance attenuation level is achieved. The controller design problem is formulated as the feasibility of the convex optimization problem, which can be solved by a linear matrix inequality （LMI） approach. Numerical examples illustrate the effectiveness of the proposed methods.