网络控制系统的模型依赖平均驻留时间调度与控制

针对具有随机短时延的资源受限网络控制系统,提出了一种新的模型依赖平均驻留时间的调度策略与反馈控制联合设计方法.该调度策略由模型依赖平均驻留时间和动态试一次就丢弃(try-once-discard,TOD)调度策略共同决定,将系统建模成带有参数不确定性的离散切换系统,基于多Lyapunov函数方法及线性矩阵不等式(linear matrix inequality,LMI)技术,给出了使闭环系统指数稳定的控制器设计和TOD调度策略下的各模态平均驻留时间条件.该联合设计方法降低了保守性,在一定程度上减少了系统模态之间的切换频率.最后通过仿真验证所提方法的有效性.     

一类线性切换系统的事件触发输出调节问题

通过设计事件触发状态反馈控制器,研究一类线性切换系统的输出调节问题.相比于时间触发控制,事件触发控制可显著地降低控制任务执行的次数.由于事件触发时刻与切换时刻的相互混合,导致切换系统控制器的设计十分困难.本文通过给出事件触发机制、状态反馈控制器和满足平均驻留时间的切换信号联合设计的方案,得到系统输出调节问题可解的充分条件.非共同坐标变换突破原有各子系统的调节器方程组具有共同解的限制.此外,为了避免Zeno现象,给出相邻事件触发间隔时间存在一个正下界.最后,应用切换RLC电路系统进行仿真验证结论的有效性.     

马尔可夫信息物理系统拒绝服务攻击安全控制

研究了马尔可夫跳变信息物理系统（CPSs）在模态依赖拒绝服务（DoS）攻击下的安全控制问题.提出了一种新颖的模态依赖事件触发策略来减少网络资源消耗.特别地，DoS攻击被设置为依赖系统模态，从而更贴近实际的应用.基于Lyapunov Krasovskii泛函方法建立了闭环系统在DoS攻击下渐近一致有界的充分性条件.更进一步，根据矩阵技术设计了所需的安全控制器.最后，通过一个实例说明了该方法的有效性.     

基于周期动态事件触发的网络化切换系统的分析与控制

针对网络化系统研究具有模态依赖平均驻留时间(MDADT)和异步的线性切换系统的周期动态事件触发$H_\infty$控制.与已有切换系统事件触发方式不同,周期动态事件触发引入动态事件触发参数,且具有最小的事件触发间隔下界,在降低数据发送数量的同时,能够有效避免奇诺行为;利用MDADT方法和多Lyapunov函数技术,给出闭环系统具有指数稳定和$H_\infty$加权性能的充分条件;在此基础上,针对周期动态事件触发机制中可能存在的异步问题,提出相应的控制器设计准则.最后,通过算例验证所得结果的优越性.     

任意相对阶下非线性切换系统的事件触发漏斗控制

针对一类具有任意相对阶且带有部分非输入到状态稳定逆动态的非线性切换系统, 提出一种动态事件触 发漏斗跟踪控制方案. 首先, 引入一个虚拟输出将任意相对阶的非线性切换系统转换为相对阶为一的非线性切换系 统. 其次, 设计各子系统的事件触发漏斗控制器和切换的动态事件触发机制, 解决候选事件触发漏斗控制器和子系 统之间的异步切换问题, 所提方案消除已有文献中为所有子系统设计共同控制器带来的保守性. 在一类具有平均驻 留时间切换信号的作用下, 保证切换闭环系统的所有信号都是有界的, 且跟踪误差一直在预设的漏斗内演化, 并排 除采样中的奇诺现象. 最后, 一个仿真例子验证方案的实用性和有效性.     

基于模型依赖驻留时间的异步切换控制

研究在模型依赖平均驻留时间切换策略下切换线性系统的异步切换控制问题,同时考虑模型依赖的控制器滞后时间的约束问题.在实际情况下,信号传输和系统检测等原因会导致控制器的切换滞后于子系统.基于这类情况,首先将子系统运行的区间划分为子系统与控制器相匹配的区间和非匹配的区间,根据模型依赖的驻留时间策略设计出各子系统的控制器;然后,结合模型依赖的控制器滞后时间、系统参数和Lyapunov稳定条件推导出合适的驻留时间设计参数,且使得异步切换系统全局一致指数稳定;最后通过数值仿真验证了所提出方法的有效性.     

饱和不确定离散切换系统的静态输出反馈控制

研究一类具有饱和输入的多胞不确定性离散切换系统在平均驻留时间切换方式下的静态输出反馈控制问题.在平均驻留时间切换信号下,基于参数依赖间断切换Lyapunov函数和几个基本引理,通过求解LMI最优问题设计出使闭环系统达到局部指数稳定的静态输出反馈控制器,并给出了系统稳定的吸引域.仿真结果表明了所提出的设计方法的有效性.     

含执行器故障的切换非线性系统的事件触发自适应模糊容错控制

本文研究在平均驻留时间约束下,一类含有执行器故障的切换非线性系统输出反馈自适应模糊事件触发容错控制问题.首先,建立了一个模态依赖的状态观测器估计不可测量状态.利用模糊逻辑系统来逼近未知项.其次,构建自适应模糊容错事件触发控制方案能够节省网络资源和数据传输.然后,通过构造多Lyapunov函数和平均驻留时间法,证明闭环系统所有状态半全局一致最终有界的同时排除了Zeno现象.最后,通过数值仿真验证该方法的有效性.     

含执行器故障的切换非线性系统的事件触发自适应模糊容错控制

本文研究在平均驻留时间约束下,一类含有执行器故障的切换非线性系统输出反馈自适应模糊事件触发容错控制问题.首先,建立了一个模态依赖的状态观测器估计不可测量状态.利用模糊逻辑系统来逼近未知项.其次,构建自适应模糊容错事件触发控制方案能够节省网络资源和数据传输.然后,通过构造多Lyapunov函数和平均驻留时间法,证明闭环系统所有状态半全局一致最终有界的同时排除了Zeno现象.最后,通过数值仿真验证该方法的有效性.     

未知周期DoS攻击下奇异摄动信息物理系统H∞滤波设计

针对奇异摄动信息物理系统在未知周期拒绝服务攻击(denial-of-service,DoS)下的状态估计问题,提出事件触发多时间尺度切换滤波器设计方法.首先,在传感器与滤波器之间引入事件触发机制确定采样数据是否传输至网络中,可以达到节约网络资源的目的;然后,在此事件触发机制的基础上,考虑未知周期Dos攻击问题,建立滤波误差切换系统,通过构建依赖奇异摄动参数的Lyapunov函数,提出奇异摄动信息物理系统切换滤波器设计方法,得到较小的估计误差,从而克服设计过程中的病态数值问题,降低网络通信中DoS攻击对系统的不良影响,保证误差系统指数稳定且满足H_∞性能,实现未知周期DoS攻击下系统的状态估计;最后,利用电路仿真算例验证所提出的滤波器设计方法的有效性.     

Stability of a class of switched stochastic nonlinear systems under asynchronous switching

The stability of a class of switched stochastic nonlinear retarded systems with asynchronous switching controller is investigated. By constructing a virtual switching signal and using the average dwell time approach incorporated with Razumikhin-type theorem, the sufficient criteria for pth moment exponential stability and global asymptotic stability in probability are given. It is shown that the stability of the asynchronous stochastic systems can be guaranteed provided that the average dwell time is sufficiently large and the mismatched time between the controller and the systems is sufficiently small. This result is then applied to a class of switched stochastic nonlinear delay systems where the controller is designed with both state and switching delays. A numerical example illustrates the effectiveness of the obtained results.     

Sampled‐data output feedback stabilization for a class of switched stochastic nonlinear systems

This paper investigates a global sampled‐data output feedback stabilization problem for a class of switched stochastic nonlinear systems whose output and system mode are available only at the sampling instants. An observer is designed to estimate the unmeasurable state and thus a sampled‐data controller is constructed with the sampled estimated state. As a distinctive feature, a merging virtual switching signal is introduced to describe the asynchronous switching generated by detecting the system mode via a sampler. By choosing an appropriate piecewise Lyapunov function, it is proved that the proposed sampled‐data controller with allowable sampling period can stabilize the considered switched stochastic nonlinear systems under an average dwell‐time condition. Finally, two simulation results are presented to illustrate the effectiveness of the proposed method.     

Stability and stabilization of switched stochastic systems under asynchronous switching

This paper studies the stability and stabilization problems for a class of switched stochastic systems under asynchronous switching. The asynchronous switching refers to that the switching of the candidate controllers does not coincide with the switching of system modes. Two situations are considered: (1) time-delayed switching situation, that is, the switching of the candidate controllers has a lag to the switching of the system modes; (2) mismatched switching situation, the switching of the candidate controllers does not match the switching of the system modes. Using average dwell time and Lyapunov-like function, sufficient conditions are established for stochastic input-to-state stability of the whole system. Also, the stabilizing controller design approach is proposed for switched stochastic linear systems. The minimal average dwell time and the controller gain are achieved. Finally, a numerical example is used to demonstrate the validity of the developed results.     

Event-triggered Control of Discrete-time Switched Linear Systems with an Arbitrary Sampling Period

In this paper, the event-triggered control problem for discrete-time switched linear systems with an arbitrary sampling period is considered. At each sampling instant, only the sampled information of system state and switching signal is available to the controller. Particularly, the sampling period is arbitrary in this paper and frequent switching is allowed to happen in an inter-event period. Based on that, by constructing a time- and mode-dependent quadratic piecewise Lyapunov function, a new globally exponentially stability (GES) result under modal dwell time (MDT) criteria is obtained. By the novel Lyapunov function and the state variable transformation technique, a statefeedback controller is designed for the switched linear system. At last, a numerical example is proposed to illustrate our approach.

     

On modeling and secure control of cyber‐physical systems with attacks/faults changing system dynamics: An average dwell‐time approach

The problem of secure control in cyber‐physical systems is considered in this work. A new modeling framework is first introduced, ie, cyber‐physical systems with attacks/faults changing system dynamics is modeled as a switched system, where the switching among subsystems is triggered by a rule generated by attackers but unknown for defenders. Based on an average dwell‐time approach incorporated by the attack frequency and duration properties, a convergence condition of the Lyapunov function on active intervals of subsystems (ie, the attack and healthy modes), under the developed switched controller, is given. Next, the unknown rule, however, leads to the asynchronous switching problem between the candidate controllers and system modes. As a result, degradation of the system performance (eg, a large chatter occurred in the system state trajectories) in the asynchronous intervals is caused. To address the difficulty, a novel switching law based on a prescribed performance is proposed, and it is shown that the asynchronous intervals are shortened by reducing adjustable parameters in the switching law. An illustrative example verifies the effectiveness of the proposed method.     

异步时滞切换正系统的有限时间镇定

研究异步切换下时滞切换正系统的有限时间控制问题,即针对控制器切换滞后于子系统切换形成的异步现象,基于平均驻留时间切换方法对切换正系统开展有限时间镇定研究.首先,将每个正子系统运行的区间划分为子系统与控制器匹配和失配区间,并构造多余正Lyapunov-Krasovskii泛函;其次,基于有限时间稳定理论,实现平均驻留时间切换律及异步时滞切换正系统有限时间镇定控制器的联合设计,并给出连续时间和离散时间两种情形下系统有限时间镇定的充分条件;最后,通过两个仿真例子验证所提出方法的有效性.     

基于观测器的网络切换模糊时滞系统鲁棒控制

针对带有随机时变时滞的非线性网络切换系统稳定控制问题进行研究,在系统状态不可测且存在不确定性的情况下,采用T-S模型将非线性网络切换系统建模为网络切换模糊系统。然后,采用平均驻留时间法（ADT）,设计出基于观测器的控制器及系统切换律,并给出网络切换模糊系统指数稳定的平均驻留时间条件。结合李雅普诺夫（LKF）方法给出时滞相关的网络切换模糊系统指数稳定的矩阵不等式条件。最后通过MATLAB数值仿真验证了该设计方法的有效性和优越性。     

Output tracking control of cascade switched nonlinear systems

The output tracking problem for cascade switched nonlinear systems is studied based on the average dwell time method in this paper. Sufficient conditions for this problem to be solvable are derived, where the zero dynamics is unstabilisable under an arbitrary switching. When the switching signal satisfies an average dwell time scheme, H_∞ output tracking is achieved by virtue of a designed switched integral controller. A numerical example is illustrated to show the effectiveness of the main result.