具有时变采样周期的网络控制系统的H∞控制

研究了具有时变采样周期的网络控制系统的H∞鲁棒控制器设计问题．提出了基于变采样周期的切换方法（采样周期在有限集合内切换），并利用该方法将存在时变采样周期、长时延以及丢包的网络控制系统建模为切换系统．在此基础上，通过把一个非凸的可行性问题转化为受线性矩阵不等式约束的多目标优化问题，研究了网络控制系统的H∞控制器设计方法．仿真结果验证了基于采样周期切换的H∞控制器设计方法的有效性．     

网络控制系统时变采样周期的建模与切换控制*

针对具有双边随机时延和丢包的网络控制系统,首先采用了主动时变采样周期的方法,利用事件和时间驱动相结合方式,传感器的采样周期可实时地跟随网络延时和丢包的变化而改变,克服了长时延和数据包错序的问题。然后将系统建立为统一的切换系统模型,结合基于平均驻留时间的方法,给出了系统状态满足指数稳定的条件,并且描述了其指数衰减率和丢包率之间的定量关系。最后通过数值例仿真验证了本文所提方法的有效性。     

时变采样周期网络控制系统的鲁棒容错控制器设计

研究具有时变采样周期网络控制系统的执行器失效的完整性问题．假设系统任意两个连续采样间隔具有上界,利用输入时延法,将时变采样周期网络控制系统等价转化为连续时变时延网络控制系统．在此基础上,基于时延条件,应用Ｌｙａｐｕｎｏｖ稳定性理论和线性矩阵不等式（ＬＭＩｓ）方法证明了鲁棒容错控制律的存在条件,设计了鲁棒容错控制器,并给出了系统完整性条件下的最大允许时延的估计方法．仿真结果验证了所提方法的可行性和有效性．     

变采样周期网络控制系统的H∞控制

时延以及数据包丢失是导致网络控制系统性能降低的重要原因.利用既是时钟驱动又是事件驱动的传感器,可以使时延与采样周期具有相同的长度,这样降低了建模随机时延的保守性.通过把具有时变采样周期的网络控制系统建模为切换系统,并利用线性矩阵不等式,本文给出了保证系统渐进稳定的充分条件,同时设计了系统的H∞控制器,仿真结果表明了本文所提出的变采样周期方法的有效性.     

变采样周期和数据包随机丢失的NCS鲁棒H∞ SymboleB控制

网络控制系统与传统的点对点控制方式不同,数据传输具有时延和随机丢包,且为了对信息资源进行合理的分配和调度常采用时变采样方式.本文首先给出NCS的离散区间动态模型,该模型以Bernoulli分布序列描述NCS数据丢包的随机性,并以不确定区间矩阵描述NCS的采样周期与传输时延的时变性;在此基础上,基于线性矩阵不等式（LMI）技术,给出具有时变有界采样周期和数据随机丢包NCS的鲁棒H∞控制器存在充分条件,且将控制器的求解问题转化为一个有限维LMI凸优化问题,便于数值计算.所设计的控制器可以保证系统渐近稳定且具有一定的H∞扰动抑制水平γ.数值仿真表明提出控制器设计方法的有效性。     

具有时变采样周期的网络化控制系统故障检测

针对具有时变采样周期和时延的网络化控制系统(NCS)故障检测问题,通过矩阵 Jordan 变换,将时变采样周期与时延的不确定霆转化为NCS系统结构参数的不确定霆,建立离散时间凸多面体不确定系统模雿。设计鲁棒故障检测滤波器(RFDF)作为残差发生器,将故障检测问题转化为RFDF的设计问题,通过陑霆矩阵不等式给出滤波器存在的充分条件。数值仿真结果表明,所设计的RFDF滤波器能较快复现故障雷号,对外部干扰和不确定的采样周期及时延具有鲁棒霆。     

变采样网络控制系统的最优保性能控制

针对具有时变有界采样周期和时延的网络控制系统,首先将其建模成一类离散动态区间系统.在此基础上,对一个给定的二次型性能指标,研究了系统的保性能控制问题,基于线性矩阵不等式(LMI)给出最优保性能控制器设计方法.利用LMI工具箱,求解十分方便.仿真结果表明该方法的有效性.     

被动变采样周期网络控制系统的H∞控制器设计

本文研究了具有被动变采样周期网络控制系统的H∞控制器设计问题。提出了基于采样周期切换的方法（采样周期在有限集合内切换），并利用该方法将具有时变采样周期及时延的网络控制系统建模为切换系统。在此基础上，通过求解满足一组线性矩阵不等式约束的多目标优化问题，研究了网络控制系统的H∞控制器设计方法。仿真结果验证了基于采样周期切换的H∞控制器设计方法的有效性。     

具有不确定丢包率和时变采样周期的Delta算子系统故障检测

研究一类由Delta算子描述具有不确定丢包率的时变采样网络控制系统故障检测问题.数据包丢失发生在传感器至控制器、控制器到执行器的数据传输过程中,丢包模型采用两个相互独立的伯努利随机变量表示,假设传感器至控制器通道中的丢包率是不确定的,其均值由常数和不确定值两部分组成.时变采样周期利用有限长切换序列表示可降低保守性.采用...     

变采样周期网络化系统鲁棒容错控制

针对网络控制系统中存在的时变采样周期与时延,通过矩阵Jordan 变换与分解, 将采样周期和时延的不确定性转变为系统结构参数的不确定性,建立了离散时间凸多面体不 确定系统模型。在此基础上,首先设计观测器,保证系统状态和故障估计收敛于实际值。接 着,根据估计的故障,设计了主动动态输出反馈鲁棒容错控制器,给出了执行器发生故障时, 系统能保持渐近稳定的充分条件。将控制器设计问题转化为以线性矩阵不等式形式为约束条 件的凸优化问题,进而得出了最优H∞鲁棒容错控制器参数的具体表达式。数值仿真验证了提 出的设计方法的有效性。     

Stability analysis of networked control systems with time-varying sampling periods

In this paper, we present an interval model of networked control systems with time-varying sampling periods and time-varying network-induced delays and discuss the problem of stability of networked control systems using Lyapunov stability theory. A sufficient stability condition is obtained by solving a set of linear matrix inequalities. In the end, the illustrative example demonstrates the correctness and effectiveness of the proposed approach.     

具有时变时滞和多包丢失的网络控制系统量化H∞控制

研究了具有时变时滞与多数据包丢失的网络控制系统(networked control systems,NCSs)的量化H∞控制问题.同时考虑传感器-控制器间的测量通道及控制器-执行器间的控制通道的多数据包丢失,并将其用满足Bernoulli分布的随机变量来表示.控制输入信号和测量输出信号分别在传感器和控制器两侧进行对数量化,量化误差描述为扇区有界不确定性.利用Lyapunov理论和线性矩阵不等式方法,得到了使得闭环NCSs满足一定H∞性能指标的均方意义下指数稳定充分条件,并给出了基于观测器的时滞相关控制器设计方法.最后,通过实例证明了该方法的有效性.     

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.     

Observer-based output feedback control of networked control systems with non-uniform sampling and time-varying delay

This paper investigates the problem of observer-based output feedback control for networked control systems with non-uniform sampling and time-varying transmission delay. The sampling intervals are assumed to vary within a given interval. The transmission delay belongs to a known interval. A discrete-time model is first established, which contains time-varying delay and norm-bounded uncertainties coming from non-uniform sampling intervals. It is then converted to an interconnection of two subsystems in which the forward channel is delay-free. The scaled small gain theorem is used to derive the stability condition for the closed-loop system. Moreover, the observer-based output feedback controller design method is proposed by utilising a modified cone complementary linearisation algorithm. Finally, numerical examples illustrate the validity and superiority of the proposed method.     

Quantitative analysis and synthesis for networked control systems with non‐uniformly distributed packet dropouts and interval time‐varying sampling periods

This paper is concerned with quantitative analysis and synthesis for a networked control system under simultaneous consideration of non‐uniformly distributed packet dropouts, interval time‐varying sampling periods and network‐induced delays. A new packet dropout separation method is proposed to separate packet dropouts from the lump sum of network‐induced delays and packet dropouts. An interval time‐varying sampling period approach, which is more general than a switched sampling period approach, is presented to model the variation of the sampling period. Then a packet dropout decomposition‐based Lyapunov functional is constructed to drive some stability criteria. Based on these stability criteria, a state feedback controller is designed to asymptotically stabilize the networked system in the sense of mean‐square. Numerical examples are given to illustrate the effectiveness of the obtained results. Copyright © 2013 John Wiley & Sons, Ltd.     

网络化控制系统的时变采样及反馈调度策略

多处理器网络化控制系统中,信息传输的时延是使控制性能变差的主要原因之一。改进型混合调度算法通过在一个基本采样周期内的多次采样,形成时变的采样周期,缩减信息传输的截止期,可使信息传输的时延大为减少;同时构建网络化控制系统的反馈调度模型,通过调节基本采样周期,及时调度信息传输,能使网络的空闲时间始终保持在一个合理状态。仿真结果表明,网络利用率有所提高,网络化控制系统的动态性能有所改善。     

网络控制系统的时延相关状态反馈控制器设计

研究了具有时延、丢包和数据包时序错乱的网络控制系统镇定问题.为了有效提高系统的控制性能,本文根据网络控制系统的特点提出一种时延相关状态反馈控制方法,并将闭环网络控制系统建模为离散时间切换模型.在此基础上,通过构造依赖于参数的Lyapunov函数给出了闭环网络控制系统的稳定条件和镇定控制器设计方法.仿真结果和实验结果表明所提方法的有效性和可用性.     

Model predictive control for networked control systems

This paper investigates the problem of model predictive control for a class of networked control systems. Both sensor‐to‐controller and controller‐to‐actuator delays are considered and described by Markovian chains. The resulting closed‐loop systems are written as jump linear systems with two modes. The control scheme is characterized as a constrained delay‐dependent optimization problem of the worst‐case quadratic cost over an infinite horizon at each sampling instant. A linear matrix inequality approach for the controller synthesis is developed. It is shown that the proposed state feedback model predictive controller guarantees the stochastic stability of the closed‐loop system. Copyright © 2008 John Wiley & Sons, Ltd.     

Iterative learning control for uncertain nonlinear networked control systems with random packet dropout

This paper proposes a novel networked iterative learning control (NILC) scheme with adjustment factor for a class of discrete‐time uncertain nonlinear systems with stochastic input and output packet dropout modeled as 0‐1 Bernoulli‐type random variable. Firstly, the equivalence relation between the realizability of controlled system and the input‐output coupling parameter (IOCP) is established. Secondly, in order to overcome the main obstacle arising from the unknown IOCP, an identification technique is developed for it. Thirdly, it is strictly proved that, under certain conditions, the tracking errors driven by the developed NILC scheme are convergent to zero along iteration direction in the sense of expectation. Finally, an example is given to demonstrate the effectiveness of the proposed NILC scheme and the merits of adjustment factor.     

Absolute stability of Lurie networked control systems

This paper is concerned with the absolute stability problem of networked control systems (NCSs) with the controlled plant being Lurie systems (Lurie NCSs), in which the network‐induced delays are assumed to be time‐varying and bounded. First, in consideration of both the time‐varying network‐induced delays and data packet dropouts, the Lurie NCSs can be modeled as a multiple‐delays Lurie system. Then, a delay‐dependent absolute stability condition is established by using the Lyapunov–Krasovskii method. Next, two approaches to controller design are proposed in the terms of simple algebra criteria, which are easily solved via the toolbox in Matlab. Furthermore, the main results can be extended to robust absolute stability of Lurie NCSs with the structured uncertainties, where robust absolute stability conditions and approaches to robust controller design are presented. Finally, two numerical examples are worked out to illustrate the feasibility and the effectiveness of the proposed method. Copyright © 2009 John Wiley & Sons, Ltd.