一类基于模型的时延网络控制系统的稳定性分析

针对连续、线性被控对象状态无法直接测量得到的情况，设计了状态观测器，在网络传输信号的时间间隔内，依据被控对象模型计算控制信号，以减少网络的使用率．在此基础上，给出了一类基于模型的时延网络控制系统全局指数稳定的充要条件，该条件受网络信号更新时间、被控对象模型误差及网络诱导时延等因素的影响．仿真结果表明了该稳定性条件的正确性．     

基于模型的网络控制系统稳定性

针对具有时间延迟的网络控制系统被控对象状态无法直接测量得到的情况，设计了状态观测器，并讨论了系统指数稳定性问题．提出了在网络传输信号的时间间隔内依据被控对象模型计算控制信号的开环控制方法，以减少对网络的使用．在此基础土，分别对连续和离散被控对象给出了网络控制系统全局指数稳定的充要条件，该条件受网络信号更新时间、被控对象模型误差及网络引起的时间延迟等因素的影响．仿真示例验证了稳定性条件的有效性。     

直流伺服电机网络控制系统时延特性的仿真研究

分析直流伺服电机网络控制系统中网络时延的分类和组成,利用基于MATLAB/Simulink的TrueTime仿真工具箱建立以直流伺服电机为被控对象的网络控制系统仿真模型,分析不同条件下网络时延对网络控制系统控制性能的影响。     

一种网络控制系统时延补偿方法

本文分析介绍了具有随机时延网络控制系统控制器设计及时延补偿方法,采用广义预测控制(GPC)算法设计控制器。针对输出时延通过对时间加上时间戳来估算时间延迟,并采用状态观测器进行时延补偿,而控制时延则采用队列机制,增加缓存器的方法来保证被控对象获得最优控制信号。通过仿真证实该方法的有效性。     

一类非线性网络控制系统的稳定性分析

网络诱导时延是影响网络控制系统稳定性和动态性能的主要因素.针对一类仿射非线性被控对象模型,利用泰勒展开进行局部线性化.考虑网络诱导时延,采用状态反馈控制器,建立基于状态反馈控制器的闭环控制系统模型.通过Lyapunov方法证明,所得最大允许时延能够保证闭环网络控制系统稳定.最后以Simulink构建一个仿射非线性被控对象模型,通过仿真证明了本文方法的正确性和有效性.     

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。     

基于GPC算法的网络控制系统研究

针对具有随机时延的一类网络控制系统(NCS),文章设计了一种基于时延补偿和广义预测控制(GPC)算法的控制器。该控制器根据数据包的时间戳计算传感器-控制器时延,通过时延补偿得到被控对象当前的状态和输出,采用GPC算法计算控制量。仿真结果证实了该控制器的有效性。     

基于内模控制的无线网络控制系统设计

无线网络控制系统由于网络的存在产生诱导时延,时延影响系统稳定性,甚至使系统失去控制。针对这一现象,提出一种基于内模控制的无线网络控制系统设计,在被控对象端添加预估模型,从结构上实现无需确知网络时延的大小,在被控对象预估模型与真实模型相等的情况下,可实现对网络时延的完全补偿。内模控制器的参数调整方便,设计方法简单并容易实现,仿真结果验证了该系统具有良好的跟踪性能,较强的鲁棒性和抗干扰能力。     

基于CMAC神经网络的网络控制系统模糊PD控制

针对网络控制系统中存在的随机诱导时延,把传输网络以及被控对象看作是一个时变的被控系统,将小脑模型神经网络与PD控制相结合,通过CMAC神经网络与PD的复合控制实现前馈反馈控制,PD控制器的参数由模糊推理机自适应整定,以减小网络诱导时延及其不确定性对系统的负面影响,优化系统控制效果。最后对该控制方法进行了仿真研究,结果表明该方法能有效改善系统的控制性能。     

基于快速输出采样反馈的网络控制系统滑模控制

针对网络控制系统的网络诱导时延问题,提出了一种新的滑模控制方法。通过快速采样被控对象输出,建立了具有线性时不变被控对象的网络控制系统的离散模型。在此基础上,用极点配置法给出了滑模切换面参数,设计了输出反馈离散滑模控制器。仿真结果验证了该控制方法的有效性。     

Analysis of networked control systems with drops and variable delays

Motivated by the insertion of a communication network in the feedback control loop, this paper focuses on how network-induced data dropouts and variable delays affect the stability of a linear plant with state feedback control. Sufficient conditions for Lyapunov stability are derived in the case of uncertainty due to drops and delays. The verification problem of the sufficient conditions can be directly cast as an LMI feasibility problem. We illustrate the methodology by an example in the cases of drops, delays and drops with delays.     

Stability and Stabilization of Networked Control Systems Under Limited Communication Capacity and Variable Sampling

This paper investigates the problem of quantized feedback control for networked control systems (NCSs) with time‐varying delays and time‐varying sampling intervals, wherein the physical plant is a continuous‐time, and the control input is a discrete‐time signal. By using an input delay approach and a sector bound method, the network induced delays, the signal quantization and sampling intervals are presented in one framework in the case of the state and the control input by quantization in a logarithmic form. We exploit a novel Lyapunov functional with discontinuity, taking full advantage of the NCS characteristic information including the bounds of delays, the bounds of sampling intervals and quantization parameters. In addition, it has been shown that the Lyapunov functional is decreased at the jump instants. Furthermore, we use the Leibniz‐Newton formula and free‐weighting matrix method to obtain the stability analysis and stabilization conditions which are dependent on the NCS characteristic information. The proposed stability analysis and stabilizing controller design conditions can be presented in term of linear matrix inequalities, which have less conservativeness and less computational complexity. Four examples demonstrate the effectiveness of the proposed methods.     

Stability of Networked Control Systems With Uncertain Time-Varying Delays

In this technical note, a new approach for the stability analysis and controller synthesis of networked control systems (NCSs) with uncertain, time-varying, network delays is presented. Based on the Jordan form of the continuous-time plant, a discrete-time representation of the NCS is derived. Using this model for delays that can be both smaller and larger than the sampling interval, sufficient LMI conditions for stability and feedback stabilization are proposed. The results are illustrated by a typical motion control example.      

双时滞离散模型的网络控制系统稳定条件

研究了具有双时滞离散线性系统的稳定性及其在网络控制中的应用。一个具有状态时滞的离散线性系统,假设它的状态信号从输出到控制器的时候,存在两种情况：第一种情况,有两条传播渠道,一条直接输入到控制器,另一条通过网络,网络传播往往会产生时滞;第二种情况是通过网络单渠道传送。基于Lyapunov稳定理论得到双时滞离散线性系统稳定的充分条件。在此基础上通过引入一些新的变量,将得到的条件转化为线性矩阵不等式（LMIs）,分别给出了两种情况下控制器的设计。最后给出的三个数值例子说明方法的有效性。     

双率采样系统的基于观测器的网络化H∞控制

研究一类带有网络传输时滞和丢包的双率采样系统的网络化H∞控制问题. 假设对象状态变量被分成两个分向量, 同一分向量的状态变量由同一类传感器以相同周期采样, 且两类传感器的采样频率不同. 采样后的分向量分别通过非理想网络传输到控制器端. 考虑到双率采样、网络传输时滞和丢包现象, 引入同步观测器来估计对象状态并设计基于估计状态的控制器来镇定双率采样系统. 基于这个思路, 将双率采样的网络化控制系统建模为带有两个时变时滞的连续系统. 利用Lyapunov-Krasovskii泛函方法, 以矩阵不等式形式给出该系统的稳定性判据和控制器设计方法. 最后, 通过数值例子验证所提方法的有效性.     

Output feedback control of networked systems

This paper considers the problem of control of networked systems via output feedback. The controller consists of two parts: a state observer that estimates plant state from the output when it is available via the communication network, and a model of the plant that is used to generate a control signal when the plant output is not available from the network. Necessary and sufficient conditions for the exponential stability of the closed loop system are derived in terms of the networked dwell time and the system parameters. The results suggest simple procedures for designing the output feedback controller proposed. Numerical simulations show the feasibility and efficiency of the proposed methods.     

Sampled‐data control of networked nonlinear systems with variable delays and drops

This paper investigates the stabilization problem of the nonlinear networked control systems (NCSs) with drops and variable delays. The NCS is modeled as a sampled‐data system. For such a sampled‐data NCS, the stability properties are studied for delay that can be both shorter and longer than one sampling period, respectively. The exponential stability conditions are derived in terms of the parameters of the plant and time delay. On the other hand, a model‐based control scheme based on an approximate discrete‐time model of the plant is presented to guarantee the stability of the closed‐loop system subject to variable time delays and packet losses. The performance of the proposed control schemes are examined through numerical simulations of an automated rendezvous and docking of spacecraft system. Moreover, the simulations show that by employing the model‐based controller, a higher closed‐loop control performance can be achieved. Copyright © 2013 John Wiley & Sons, Ltd.     

Stabilization of networked control systems with nonuniform random sampling periods

In this paper, a new linear delayed delta operator switched system model is proposed to describe networked control systems with packets dropout and network‐induced delays. The plant is a continuous‐time system, which is sampled by time‐varying random sampling periods. A general delta domain Lyapunov stability criterion is given for delta operator switched systems with time delays. Sufficient conditions for asymptotic stability of closed‐loop networked control systems with both packets dropout and network‐induced delays are presented in terms of linear matrix inequalities (LMIs). A verification theorem is given to show the solvability of the stabilization conditions by solving a class of finite LMIs. Both the case of data packets arrive instantly and the case of invariant sampling periods in delta operator systems are given, respectively. Three numerical examples are given to illustrate the effectiveness and potential of the developed techniques. Copyright © 2010 John Wiley & Sons, Ltd.     

遥操作机器人系统的透明性鲁棒控制

针对遥操作机器人系统中由于传输通道存在时滞,导致系统不稳定和系统性能下降的问题,将系统描述成一个具有多状态时滞的状态空间模型,通过透明性分析给出控制器增益矩阵需要满足的约束条件,再利用一种基于时滞划分的Lyapunov-Krasovskii泛函法进行稳定性分析并给出稳定性条件,得到既能保证稳定性,又具备一定透明性的控制器。仿真实验结果表明了该方法的有效性。