Quantized H ∞ fault-tolerant control for networked control systems

Quantized H_∞ fault-tolerant control for networked control systems (NCSs) with partial actuator fault with respect to actuators is concerned in this paper. Considering transmission delay, packet dropout and quantization, a synthesis model with partial actuator fault is established. The piecewise constant controller is adopted to model NCS with the transmission delay and packet dropout. Due to data transmitted in practical NCSs should be quantized before they are sent to the next network node, the logarithmic static and time-invariant quantizers at the sensor and controller sides are proposed in the paper. For the established model, an appropriate type of Lyapunov functions is provided to investigate the delay-dependent H_∞ control problem. According to an optimal problem, the controller that makes the system achieve the best performance is designed. Finally, an illustrative example is given to demonstrate the effectiveness of the proposed approach.     

一类网络化控制系统的稳定容错控制

In this paper, we use the matrix measure technique to study stable fault-tolerance control of networked control systems. State feedback networked control systems with the network-induced delay, parameter uncertainties, sensor failures and actuator failures are considered. State feedback gain K is designed for any invariant delay , and some theorems and sufficient conditions for stable fault-tolerance control are given. Example is presented to illustrate the effectiveness of these theorems.     

CAN型网络化控制系统的混合带宽优化

A hybrid bandwidth scheduling scheme is proposed to improve the quality of service and the bandwidth utilization for the CAN-based networked control systems. It combines rate monotonic and improved round-robin scheme for both the real-time and non-real-time data. Moreover, considering the constraints of control performance and network schedulability, a heuristic branch and bound genetic algorithm (GA) algorithm is presented for the control data to minimize their bandwidth occupancy and the jitter caused by improper scheduling. The residual bandwidth is allocated to non-real-time data by the proposed scale round-robin scheme such that their network loads are balanced.     

Robustness analysis and distributed control of a networked system with time-varying delays

This paper is concerned with the robustness analysis and distributed output feedback control of a networked system with uncertain time-varying communication delays. This system consists of a collection of linear time-invariant subsystems that are spatially interconnected via an arbitrary directed network. Using a dissipation inequality that incorporates dynamic hard IQCs (integral quadratic constraints) for the delay uncertainties, we derive some sufficient robustness conditions in the form of coupled linear matrix inequalities, in which the coupled parts reflect the interconnection structure of the system. We then provide a procedure to construct a distributed controller to ensure the robust stability of the closed-loop system and to achieve a prescribed $\ell_2$-gain performance. The effectiveness of the proposed approach is demonstrated by some numerical examples.     

网络控制系统中随机传输时延的预测补偿研究

This paper proposes a predictive compensation strategy to reduce the detrimental effect of stochastic time delays induced by communication networks on control performance. Values of a manipulated variable at the present sampling instant and future time instants can be determined by performing a receding horizon optimal procedure only once. When the present value of the manipulated variable does not arrive at a smart actuator, its predictive one is imposed to the corresponding process. Switching of a manipulated variable between its true present value and the predictive one usually results in unsmooth operation of a control system. This paper shows: 1) for a steady process, as long as its input is sufficiently smooth, the smoothness of its output can be guaranteed; 2) a manipulated variable can be switched smoothly by filtering the manipulated variable just using a simple low-pass filter. Thus the control performance can be improved. Finally, the effectiveness of the proposed method is demonstrated by simulation study.     

具有反馈增益摄动的网络化控制系统H∞控制

在考虑系统状态反馈增益发生加性不确定摄动的情况下,基于线性矩阵不等式(LMI)方法,研究了具有网络诱导时延的网络化控制系统(NCS)H∞非脆弱控制器的设计问题.以线性矩阵不等式形式给出控制器存在的充分条件,通过求解LMI得出控制器参数.数值示例表明,当其控制器增益不确定时,所提H∞非脆弱控制器仍保证NCS渐近稳定,并具有所期望的H∞性能;而当控制器增益不确定时,由H∞鲁棒控制控制器控制的NCS将不稳定.     

应用信度分配的模糊CMAC实现非线性系统的容错控制

The adaptive fault-tolerant control scheme of dynamic nonlinear system based on the credit assigned fuzzy CMAC neural network is presented. The proposed learning approach uses the learned times of addressed hypercubes as the credibility, the amounts of correcting errors are proportional to the inversion of the learned times of addressed hypercubes. With this idea, the learning speed can indeed be improved. Based on the improved CMAC learning approach and using the sliding control technique, the effective control law reconfiguration strategy is presented. Thesystem stability and performance are analyzed under failure scenarios. The numerical simulation demonstrates the effectiveness of the improved CMAC algorithm and the proposed fault-tolerant controller.     

基于网络化控制系统的硬件实验平台构建

构建了基于网络化控制系统的硬件实验平台,使网络化控制系统的研究成果能尽快地得以推广应用。介绍了该硬件实验平台组成结构,它由主控模块、远程数据采集和通信模块、被控对象等3大部分构成。在介绍了各模块的主要功能基础上,阐述了利用Visual C++完成主控模块需要解决的关键问题和初步设计方案,并给出了利用ADCU842和CS8900 实现数据采集和远程通信的硬件结构框图和初步设计方案,基本完成了对硬件实验平台的构建工作。该实验平台提供了硬件实验环境,研究者可以轻松地编写相应算法程序。     

基于等分采样周期的网络控制系统故障检测

考虑一类时延网络控制系统,假定其存在输出时延,对其进行故障检测。通过提高控制器端的采样频率,将传感器采样周期等分,这样可以将网络时延近似看成控制器端采样周期的整数倍。在此基础上,建立了基于离散异步动态系统的故障观测器误差方程,并将观测器稳定条件归结为一个线性矩阵不等式。当系统正常时,只要给定的不等式条件成立,该观测器系统就是稳定的。当系统发生故障时,观测器残差能够迅速发生跳变,从而检测出故障的发生。最后通过仿真实例验证了方法的有效性。     

基于传感器故障的网络化系统鲁棒容错设计

针对一类具有参数不确定的非线性网络化控制系统,基于T-S模糊模型建模,推证出了确保非线性网络化控制系统在传感器发生失效故障时具有鲁棒完整性的时滞依赖充分条件,并以求解矩阵不等式给出了容错控制器的设计方法.最后以一个仿真算例验证了文中所述方法的可行性和有效性.     

带有通讯约束的网络化控制系统容错控制技术研究

文中研究了针对具有通讯约束的网络化控制系统存在执行器增益故障的容错控制问题. 提出一种静态调度策略, 利用周期通讯序列的方法调度网络资源及网络可用通道. 该研究的创新处在于首先将具有周期通讯序列及执行器故障的网络化控制系统建模为一个周期的切换系统, 并提出了基于调度依赖的利亚普诺夫函数方法对系统容错控制器进行设计. 由于调度策略使得在每个采样时刻存在数据丢失, 文中分别利用0值和上一时刻采样值替代所丢失的数据. 更进一步的, 当考虑控制对象存在外界能量有界干扰时, 分别就上述两种情况讨论了其鲁棒容错控制器的设计问题. 最后, 通过仿真实例证明了所提方法的有效性.     

网络控制系统研究综述与展望

介绍了网络控制系统(networked control system,NCS)中存在的基本问题.从网络体系架构、线性及非线性NCS建模与设计、控制与调度协同设计、故障检测与容错控制等5个方面综述了网络控制系统的研究成果和最新进展.最后阐述了该领域亟待解决的关键问题和进一步的研究方向.     

一类随机时延网络化控制系统的容错控制研究

将一类具有随机时延的网络化控制系统建模为具有马尔可夫延迟特性的离散跳变线性系统．借助跳变线性系统理论和容错控制的思想，研究了随机时延网络化控制系统的执行器失效问题．仿真结果验证了所提方法的有效性．     

存在通信约束和时延的多输入多输出网络控制系统镇定研究

讨论了一类存在通信约束和时延的多输入多输出网络控制系统（NCS）的建模和控制问题.该NCS具有多个传感器和执行器，由于网络通信受限,在同一时刻只能允许部分传感器和执行器访问网络.传感器和执行器访问网络的过程可以用两个马尔可夫链来描述,并且在假设传感器—控制器时延和控制器—执行器时延均为短时延的情况下,将整个闭环NCS建模成一个具有两个模式的马尔可夫切换系统.基于LMI技术和李亚普诺夫方法,给出了闭环NCS随机稳定的充分条件,并给出了状态反馈控制器的设计方法.最后的数值算例验证了所提方法的有效性.     

网络控制系统的安全域研究

基于网络控制系统(networked control system,NCS)的网络空间特性,对NCS信息安全的时空特性和NCS的安全域进行了研究,在此基础上提出了一种具有自律可控性和自律可协调性的NCS安全域的新型体系结构,并对新构建的NCS安全域体系的一些关键问题进行了探讨。     

分布式入侵检测技术在网络控制系统中的应用

随着控制系统复杂性的日益扩大,控制系统的网络化是控制系统发展的必然。自动控制、计算机网络和通讯技术的融合,为实现控制和管理信息一体化提供了一条新思路,但也带来以一系列安全问题,如何保障网络控制系统的安全是当前控制网络信息建设的研究热点。文中通过分析网络控制系统的结构和对网络安全的要求,提出了将分布式入侵检测技术运用到网络控制系统的具体方案,并对相关技术和网络安全体系的建设进行了讨论。     

基于双观测器的网络控制系统稳定性分析

网络控制系统存在网络诱导时延和数据包丢失等问题,使网络控制系统控制性能下降甚至导致系统不稳定,同时在实际应用中存在双闭环的情况,并且一些系统的状态不可测量。针对上述问题,设计2个状态观测器,利用测量输出进行状态重构,并采用状态观测器对丢包进行补偿,应用指数稳定定理分析整个系统的闭环稳定性,给出状态控制率的求解方法。仿真结果证明,该方法能有效补偿网络控制系统的性能,保证在时延和有数据包丢失情况下的网络控制品质。     

高阶模糊控制器在网络控制系统中的应用

当网络控制系统存在非线性随机延迟时，不能直接使用传统的控制方法。针对这种随机延迟该文提出了高阶模糊控制方法。该方法在经典PID控制器的理论基础上进行改进，增加了系统输出的高阶信息，同时利用模糊控制理论对控制器参数进行在线自适应调节。为此该文首先简要地介绍了网络控制系统中存在的随机延迟，然后分析了延迟引起的非线性特征。结合该文的算法思想和模糊控制器的设计原理给出模糊控制器的设计过程。最后给出了应用此方法的一个仿真实例。