Design of Networked Control Systems With Packet Dropouts

This note is concerned with stability and controller design of networked control systems (NCSs) with packet dropouts. New NCS models are provided considering both single- and multiple-packet transmissions. Both sensor-to-controller (S/C) and controller-to-actuator (C/A) packet dropouts are modeled and their history behavior is described by different independent Markov chains. In term of the given models, sufficient conditions for stochastic stability are derived in the form of linear matrix inequalities (LMIs) and corresponding control laws are given. Numerical examples illustrate the effectiveness of the results.     

Robust Stabilization of Uncertain Networked Control Systems with Data Packet Dropouts

The data packet dropouts phenomenon is usually inevitable when information transmit- ted among communication networks.In this paper,the robust stabilization problem for uncertain networked control systems with data packet dropouts is studied.First,an uncertain discrete-time switching system model is presented to describe these networked control systems.The stability equiv- alence is then proved between this switching system and an uncertain impulsive difference system. Moreover,a sufficient condition is obtained for the asymptotical stability of the nonlinear impulsive difference system.From this condition the robust stabilization problem is dealt with for the uncertain impulsive system.Main results are given in linear matrix inequalities.Finally a numerical example is given to illustrate the theoretical results.     

Networked Iterative Learning Control Design for Nonlinear Systems with Stochastic Output Packet Dropouts

This paper develops two proportional‐type (P‐type) networked iterative learning control (NILC) schemes for a class of discrete‐time nonlinear systems whose stochastic output packet dropouts are modeled as 0‐1 Bernoulli stochastic sequences. In constructing the NILC schemes, two kinds of compensation algorithm of the dropped outputs are given. One is to replace the instant‐wise dropped output data with the synchronous desired output data; the other is to substitute the dropped data with the consensus‐instant output data used at the previous iteration. By adopting the lifting technique, it is derived that under certain conditions the expectations of the tracking errors incurred by the proposed NILC schemes converge to zero along the iteration axis. Numerical experiments are carried out for validity and effectiveness.     

EPA网络控制系统丢包分析

针对基于时钟同步技术的时分调度网络控制系统工作方式,分析了基于EPA协议的网络丢包原理.建立在不同实时性要求情况下EPA网络系统的丢包模型,并且分析了时钟偏差抖动为马尔科夫链时,通信周期、时间片长度以及时钟同步精度对系统稳定性的影响.提出了提升EPA系统实时性的方法.最后对EPA系统的稳定性进行了分析.     

不确定控制系统的输出反馈镇定

本文研究具有匹配和非匹配不确定性系统的输出反馈镇定。在对不确定性的增长性作适当限制的条件下，利用本文引入输出反馈严格正实系统的概念，构造了保证团环系统在开球Ｂ上或在Ｒ＾ｎ上指数式稳定的光滑或解析输出反馈控制律。     

Output Feedback Stabilization of Linear Systems With Actuator Saturation

The note presents a method for designing an output feedback law that stabilizes a linear system subject to actuator saturation with a large domain of attraction. This method applies to general linear systems including strictly unstable ones. A nonlinear output feedback controller is first expressed in the form of a quasi-LPV system. Conditions under which the closed-loop system is locally asymptotically stable are then established in terms of the coefficient matrices of the controller. The design of the controller (coefficient matrices) that maximizes an estimate of the domain of attraction is then formulated and solved as an optimization problem with LMI constraints     

移动机器人网络控制系统的输出反馈控制

以线性时不变系统为被控对象,建立了四轮移动机器人网络控制系统的离散数学模型。诱导时延是影响系统性能的关键因素,通过在节点中设置缓冲区的方法可以将网络控制系统中的随机诱导时延转化为确定性时延,从而将网络控制系统由随机系统转化为确定性系统。通过被控对象移动机器人控制实验系统,设计了一个能处理网络诱导时延的输出反馈控制器,分析了采样周期和网络诱导时延对网络控制系统稳定性的影响。仿真结果表明了该控制器和控制策略的正确性及有效性。     

不确定有损网络控制系统的鲁棒镇定

The data packet dropouts phenomenon is usually inevitable when information transmitted among communication networks. In this paper, the robust stabilization problem for uncertain networked control systems with data packet dropouts is studied. First, an uncertain discrete-time switching system model is presented to describe these networked control systems. The stability equivalence is then proved between this switching system and an uncertain impulsive difference system. Moreover, a sufficient condition is obtained for the asymptotical stability of the nonlinear impulsive difference system. From this condition the robust stabilization problem is dealt with for the uncertain impulsive system. Main results are given in linear matrix inequalities. Finally a numerical example is given to illustrate the theoretical results.     

有界丢包网络控制系统的稳定性与能稳性

主要讨论有界丢包网络控制系统的稳定性与能稳性. 基于迭代方法将有界丢包网络控制系统建模为一个跳变系统. 由于网络的复杂性, 跳变系统状态转移矩阵的部分元素无法获得, 因此, 我们考虑的这种情况更具有一般性. 并且本文考虑的丢包同时存在于前馈和反馈通道. 最后, 数值例子表明本文方法的有效性.     

Detectability and Output Feedback Stabilizability of Nonlinear Networked Control Systems

This note addresses problems of detectability and output feedback stabilizability of nonlinear systems with globally Lipschitz nonlinearities via limited capacity digital communication channels. The main results are given in terms of Riccati algebraic inequalities. A simulation result on the control of a flexible joint robotic system is also presented     

时延网络化控制系统的量化输出反馈耗散控制

以带有时变时延的离散网络化控制系统为研究对象,研究了闭环系统的量化输出反馈耗散控制问题。引入两个对数量化器分别对系统中的测量输出信号和控制输入信号进行量化,利用扇形界方法,将量化反馈控制设计问题通过扇形界的不确定性转化为鲁棒控制问题进行求解。通过借助自由权矩阵方法,得到了非脆弱耗散控制器存在的充分条件。所设计的控制器能够保证闭环系统渐近稳定且严格(Q,R,S)—耗散。最后通过理论证明及数值仿真验证了所提控制策略的有效性。     

Hybrid Scheduling and Quantized Output Feedback Control for Networked Control Systems

A novel co-design scheme of hybrid scheduling strategy, adaptive logarithmic quantizer and dynamic robust H-infinity output feedback controller for a class of networked control system (NCS)with communication constraints and time delay is proposed. The hybrid scheduling scheme integrates dead zone scheduling and Try Once Discard (TOD) scheduling so as to get the stronger adaptability and flexibility than the single scheduling. In this scheme, dead zone scheduling which updates the threshold according to mode-dependent control strategy is used for single node of NCS to reduce the network bandwidth utilization while TOD scheduling is used for the whole node of NCS in order to meet the requirements of communication constraints and guarantee the overall system performance.We develop the integrated design for the hybrid scheduling strategy, adaptive quantizer and dynamic robust output feedback controller to maintain asymptotic stability of the closed-loop NCS by using the multiple-Lyapunov function and switched system theory. The proposed method can improve the the quality of service (QoS) meanwhile ensure the quality of control (QoC) of overall systems, which make a better trade-off between network utilization and control performance. An simulation example demonstrates the efficiency of the proposed method.     

非线性微分——代数系统的输出反馈镇定控制

对满足线性增长条件的非线性微分--代数系统, 研究了其输出反馈镇定控制问题. 通过将状态观测器与控制器耦合在一起设计, 构造出一种非初始化的线性高增益状态观测器, 具有良好的鲁棒性. 基于反推设计方法构造出一个线性的动态输出补偿器, 使得整个闭环系统是渐近稳定的. 仿真结果验证了本文所提控制方法的有效性.     

Stabilization of Networked Control Systems With a Logic ZOH

The technical note is concerned with the stabilization problem of networked control systems. A general framework is proposed firstly, where the zero-order hold has the logical capability of choosing the newest control input packet. The continuous-time process is discretized as a system with input delays. Then a sufficient condition for testing the stability of the discretized system and two sufficient conditions for designing a stabilizing controller are established based upon the Lyapunov theory. Finally numerical examples and simulations are used to illustrate the developed theory.      

基于误差阈值通信逻辑的输出反馈网络控制系统设计

针对网络控制系统被控对象状态无法直接测量的情况,设计了状态观测器,给出了一种基于误差阈值的确定通信逻辑,应用于基于模型的网络控制系统中,提出了具有确定通信逻辑的网络控制系统结构,建立了系统模型,仿真数例表明加入确定通信逻辑后,在保持系统稳定的情况下,数据发送的次数明显减少,有效地减轻了网络负载。     

Stabilization of Networked Control Systems With a New Delay Characterization

This paper presents a new approach to solving the problem of stabilization for networked control systems. Mean-square asymptotic stability is derived for the closed-loop networked control systems, and based on this, a controller design procedure is proposed for stabilization purpose. An inverted pendulum system is utilized to show the effectiveness and applicability of the proposed results.     

带未知通信干扰和丢包补偿的多传感器网络化不确定系统的分布式融合滤波

研究了带有未知通信干扰、观测丢失和乘性噪声不确定性的多传感器网络化系统的状态估计问题.通过白色乘性噪声描述系统状态和观测中的随机不确定性,采用一组服从Bernoulli分布的随机变量描述网络传输过程中存在的观测丢失现象,且数据传输中存在未知的网络通信干扰.当发生丢包时,以当前丢失观测的预报值进行补偿.对每个单传感器子系统,应用线性无偏最小方差估计准则设计了不依赖于未知通信干扰的最优线性滤波器.推导了任两个局部滤波误差之间的互协方差阵.进而,应用矩阵加权融合估计算法给出了分布式融合状态滤波器.仿真例子验证了算法的有效性.     

一类基于观测器状态反馈镇定的网络化控制系统

本文研究仅仅在传感器与控制器之间存在网络的网络化控制系统的观测器以及控制器的设计问题．考虑系统同时存在随机时滞和数据包丢失的情况，通过求解线性矩阵不等式，设计出了保证网络化控制系统渐近稳定的观测器以及控制器．最后给出一个实例说明了此设计方法是有效的．     

具有时滞的Lurie型组合系统的分散输出反馈镇定

通过构造一比较系统,将Lurie型组合系统的稳定性问题转化为讨论维数较低的比较系统的稳定性问题,并利用M矩阵特性导出比较系统稳定的一个充分条件;为求取输出反馈增益,建立等价的稳定条件的QLMI表示形式.这一方法的特点是使大系统的稳定控制器设计的复杂度保持在子系统一级的水平上,给出的实例说明算法在实际工程应用中是有效的.     

一种带有动态输出反馈控制器的网络控制系统的Markov跳变模型

对于网络控制系统(Networked control systems, NCS)中的随机延迟时变有界, 其上界大于一个采样周期的情况, 建立了带有动态输出反馈控制器的连续时间系统模型. 以此为基础, 应用连续时间系统模型离散化与增广状态空间方法, 建立了受控于有限状态Markov链的离散时间跳变系统模型. 在该系统的稳定性控制器设计中, 给出了一种求内点法的初始可行解的方法, 从而解决了所建模型的可解性问题. 理论分析和车载倒立摆上的仿真计算表明, 由上述模型与改进算法所给出的动态输出反馈控制器能使系统稳定.