资源约束系统的信息调度及其渐近稳定性

对于通信约束的网络控制系统,应用通信序列的概念和混合逻辑动态的构架,将其建模成一类集成控 制和调度的资源约束离散线性周期系统．给出了这类系统网络信息的可调度条件,并基于线性矩阵不等式设计动态 反馈控制律．仿真表明,该方法能够在网络信息的周期调度下使闭环系统渐近稳定．     

具有通信约束的网络控制系统动态调度与H∞控制协同设计

针对一类具有通信约束的随机时延网络控制系统,提出一种基于试一次丢弃(try-once-discard,TOD)动态调度策略与鲁棒H∞控制器协同设计的方法.考虑通信约束和随机时延的影响,将系统建模为一类具有参数不确定性的离散切换系统,并采用切换系统和Lyapunov稳定性理论,给出了TOD调度策略下使闭环系统渐近稳定的鲁棒H∞控制器设计方法.最后通过仿真验证了方法的有效性.     

基于分段模糊Lyapunov方法的T-S模糊系统H∞控制

针对具有外部扰动的T-S模糊系统，利用分段模糊Lyapunov函数和线性矩阵不等式方法研究了模糊系统的镇定问题．给出了闭环系统渐近稳定的充分条件，提出了闭环系统γ一次优H∞控制器的参数化设计方法．仿真实例验证了所提出方法的有效性．     

机器人系统输出反馈重复学习轨迹跟踪控制

针对高度非线性多关节机器人的轨迹跟踪问题,提出一类输出反馈重复学习控制算法,使得在只有位置信息可测以及模型信息不确定的条件下即能获得良好的控制品质.非线性滤波器的引入解决了现实中速度信号较难获得的问题,重复学习控制策略实现了对周期性参考输入的渐近稳定跟踪.应用Lyapunov直接稳定性理论证明了闭环系统的全局渐近稳定性.三自由度机器人系统数值仿真结果表明了所提出的输出反馈重复学习控制的有效性.     

一类不确定时滞奇异系统的鲁棒非脆弱控制

针对不确定奇异时滞系统，研究了鲁棒非脆弱控制问题。假定不确定性范数有界，设计了基于观测器的控制器，使得闭环系统在不确定性影响下保持鲁棒稳定。仅通过求解相应线性矩阵不等式就可得到鲁棒状态反馈控制器，该控制器不仅对所有容许的系统不确定性使相应的闭环系统渐近稳定，而且满足控制器本身是非脆弱的，达到抑制干扰的效果。     

具有通信约束和时延的NCS状态反馈镇定

基于通信序列并考虑不确定短时延的影响,对具有通信约束的网络控制系统进行建模,使其成为参数不确定的集成信息调度与控制离散切换系统。基于切换系统理论和分段Lyapunov函数方法,以矩阵不等式形式给出在一定周期性信息调度策略下,使系统渐近稳定的条件,阐述状态反馈控制器的设计方法。仿真结果证明了该方法的有效性。     

一类不确定模糊动态时滞系统保成本控制

针对一类不确定非线性动态时滞系统，利用模相T—S模型，通过状态反馈对保成本控制问题进行研究。应用线性矩阵不等式给出模糊闭环系统渐近稳定的充分条件，保证了所有允许的不确定闭环系统是稳定的，而且对于一个给定的二次型成本函数，舱保证闭环成本不超过某个界。仿真结果表明所提出的控制方法是有效的。     

交直流并联输电系统的非线性鲁棒控制

针对含有常参数不确定性的交直流输电系统，使用自适应逆推方法设计了直流系统的非线性鲁棒控制器，基于该方法的设计，无需对原系统进行反馈线性化，并能保证闭环误差系统的渐近稳定，设计过程表明逆推方法设计的控制器拥有更优越的性能。     

一类具有不确定的互联大系统分散鲁棒输出跟踪控制器设计

针对一类具有不确定的互联大系统，研究了使受控系统鲁棒稳定和渐近跟踪参考输入的分散鲁棒跟踪控制器的设计问题，并对具有分散反馈控制器的闭环大系统，给出了其鲁棒稳定以及渐近跟踪的证明。     

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.     

分布式网络化控制系统优化协同设计

网络化控制系统的性能不仅与控制器的设计有关还与网络QoS有密切的联系;针对基于CAN总线协议的多闭环控制系统共享网络带宽的控制与资源调度协同设计问题,首先给出连续控制系统性能指标与传输延迟、采样周期的近似线性关系,然后以此为目标函数,以不可抢占RM可调度性和控制系统稳定性为约束条件,分配网络带宽,使控制系统整体性能最优,并对得到的传输周期进行谐调化处理,提高网络利用率;采用资源预留方法在不影响周期数据实时性的前提下,保证非周期数据的平均响应时间;最后将协调设计结果应用于某基于CANopen协议的分布式控制实验系统,控制3组倒立摆,通过研究脉冲响应并已有的调度策略比较说明了所提出策略可以有效提高控制系统性能及带宽利用率.     

Guaranteed cost control for networked control systems

The guaranteed cost control problem for networked control systems (NCSs) is addressed under conmmnication constraints and varying sampling rate. First of all, a simple inFormation-scheduling scheme is presented to describe the scheduling approach of system signals in NCSs. Then, based on such a scheme and given sampling method, the design procedure in dynarmic output feedback manner is also derived which renders the closed loop system to be asymptotically stable and guarantees an upper bound of the LQ pefformance cost function.     

Stability analysis of nonlinear processes using empirical state affine models and LMIs

A novel methodology is proposed for the analysis of robust stability of a nonlinear process under PI (Proportional-Integral) control. The analysis is based on state-affine empirical models regressed from input-output data. The state model is represented by a set of polynomial matrices nonlinear with respect to the manipulated variables. This model in combination with a linear PI controller results in a closed loop model that can be shown to lie in a polytope of matrices. This allows for the formulation of a Lyapunov stability test in terms of a simple set of LMIs (linear matrix inequalities). This set of inequalities can be also expanded to account for input saturation. The stability analysis produces regions of stability, in terms of the PI controller parameters, that are significantly larger than the regions previously calculated by a singular value test. The issues of saturation and modeling error are also incorporated into the analysis. The technique permits also to test the stability of the closed loop system with a gain scheduling PI controller. The conservativeness of the analysis is assessed by comparison to closed loop simulations of a highly nonlinear CSTR (continuous stirred tank reactor) under PI control.     

Robust event‐triggered model predictive control for cyber‐physical systems under denial‐of‐service attacks

This paper investigates the resilient control problem for constrained continuous‐time cyber‐physical systems subject to bounded disturbances and denial‐of‐service (DoS) attacks. A sampled‐data robust model predictive control law with a packet‐based transmission scheduling is taken advantage to compensate for the loss of the control data during the intermittent DoS intervals, and an event‐triggered control strategy is designed to save communication and computation resources. The robust constraint satisfaction and the stability of the closed‐loop system under DoS attacks are proved. In contrast to the existing studies that guarantee the system under DoS attacks is input‐to‐state stable, the predicted input error caused by the system constraints can be dealt with by the input‐to‐state practical stability framework. Finally, a simulation example is performed to verify the feasibility and efficiency of the proposed strategy.     

Finite word length stability issues in an l1 framework

The paper addresses the digital controller structure problem for the closed loop stability of a feedback digital control system subject to finite word length (FWL). A new method of maximizing the stability subject to perturbations in the digital controller implementation is proposed. The approach is based on structured perturbation theory in an l₁ framework, and unlike some previous approaches, can be simply extended to consider closed loop nominal performance and closed loop robust performance and stability. The method is demonstrated with application examples.     

Tuning of Gaussian stochastic control systems

A closed-loop system consisting of a control system and an adaptive controller is called tuning for a specified control objective if the real system and the ideal system defined below achieve the same value for the control objective. The real system is the system consisting of the unknown control system in closed loop with the adaptive controller in which the parameters of the adaptive controller have been determined by identification under feedback or in closed loop. The ideal system is the system consisting of the unknown control system in closed loop with a controller in which the controller has been synthesized with knowledge of the unknown control system and such that the closed-loop system satisfies the control objective. Both the Gaussian stochastic control system with full observations and with partial observations are considered. The approach to the problem is based on stochastic realization theory for Gaussian systems. The control objectives of minimum variance control and pole placement are also given. Necessary conditions for tuning are discussed     

Input‐to‐state stability of switched nonlinear systems with delay in the active mode detection

A switched nonlinear system subject to disturbances is considered in this paper. The switching signal admits an average dwell time and a state feedback control depending on the system operating modes, detected with a maximum time delay, is applied to the system. In this framework, the input‐to‐state stability problem of the closed‐loop system is addressed. Based on some established existence conditions of mode‐dependent Lyapunov‐like functions, the values of the maximum time delay and the average dwell time that allow to achieve the input‐to‐state stability of the closed‐loop system are determined. In order to obtain more tractable results, the existence conditions of the mode‐dependent Lyapunov‐like functions are given in terms of sum‐of‐squares programming in the case of polynomial nonlinearities. In the linear case, they are expressed in terms of linear matrix inequalities and a procedure for the synthesis of the mode‐dependent controller is provided in this situation. The established theoretical results are illustrated through a control problem of a building ventilation system and a switched control problem of a vehicle suspension system.     

LMI optimization approach to robust decentralized controller design

A new approach for design of robust decentralized controllers for continuous linear time‐invariant systems is proposed using linear matrix inequalities (LMIs). The proposed method is based on closed‐loop diagonal dominance. Sufficient conditions for closed‐loop stability and closed‐loop block‐diagonal dominance are obtained. Satisfying the obtained conditions is formulated as an optimization problem with a system of LMI constraints. By adding an extra LMI constraint to the system of LMI constraints in the optimization problem, the robust control is addressed as well. Accordingly, the decentralized robust control problem for a multivariable system is reduced to an optimization problem for a system of LMI constraints to be feasible. An example is given to show the effectiveness of the proposed method. Copyright © 2010 John Wiley & Sons, Ltd.     

带有稀疏执行器故障的事件触发网络化系统容错控制

针对一类具有事件触发信息传输机制的网络化控制系统,对系统故障执行器个数进行稀疏约束,研究系统在有限个执行器失效情况下的指数稳定及控制器设计问题。将系统故障执行器个数的约束转化为对控制器增益矩阵行的势约束,利用混合整数方法来解决这类稀疏约束的容错控制问题。在此基础上,利用Lyapunov泛函方法,得出闭环系统在有限个执行器失效情况下系统呈指数稳定的充分条件以及具有行稀疏约束的控制器设计方法。最后,通过一个飞行控制系统的数值仿真实例验证所提控制方法的可行性和有效性。     

耦合大系统的一种分散鲁棒自适应控制解

针对连续耦合大系统给出一种间接分散非奇异鲁棒自适应控制器，控制算法采用参数辨识修正方法来克服可能出现的辨识子模型不可控问题。在不依赖外加持续激励信号和不预先假设未知系统参数空间具有凸性质的基础上，保证整个闭环系统的全局渐近稳定性。它对各子系统间存在的弱耦合、未建模动态误差和有界扰动具有鲁棒性。