基于T-S模型的网络控制系统故障诊断

针对一类参数不确定并具有时延和丢包情况的非线性网络控制系统,为达到快速准确的进行故障诊断的目的,提出了一种基于T-S模糊模型的故障诊断方法.通过建立此系统的T-S模糊模型,利用平行分布补偿时延的思想设计了满足系统稳定性条件的状态反馈控制器,以及通过引入随机切换系统表示数据有无丢失情况下的基于模糊观测器的鲁棒故障诊断方法,然后基于 Lyapunov函数和线性矩阵不等式方法给出了该闭环网络控制系统渐近稳定的充分条件,最后通过仿真例子验证了该方法能够使闭环控制系统渐进稳定以及能够准确的进行故障诊断,验证了所设计方法的有效性.     

基于观测器的不确定T-S模糊系统鲁棒镇定

为带有参数不确定性的T-S模糊控制系统提出了新的基于观测器的鲁棒输出镇定条件. 该条件用来设计模糊控制器和模糊观测器. 为了设计模糊控制器和模糊观测器, 用T-S模糊模型来表示非线性系统, 并运用平行分布补偿观念. 充分条件基于二次Lyapunov函数, 通过将模糊系统的鲁棒镇定条件表述为一系列矩阵不等式, 比以往文献中列出的条件具有更小的保守性. 该不等式为双线性矩阵不等式, 可分两步骤先后解得使T-S模糊系统镇定的控制器增益和观测器增益. 最后, 通过对一个具有不确定性的连续时间非线性系统控制的例子证明了提出方法比以往方法更宽松.     

带有丢包的线性参数变化系统的H∞控制

主要研究了一类带有Lipschitz非线性和随机通信丢包的线性参数变化系统（LPV）基于观测器的[H∞]控制问题。针对信号传递中的随机丢包,使用了已知条件概率分布的Bernoulli分布序列来描述。在随机丢包存在的情况下,利用李雅普诺夫稳定性定理得到了基于观测器的反馈控制器存在的充分条件,使得闭环网络LPV系统不仅是均方指数稳定的,而且满足预定的[H∞]扰动抑制性能指标;然后利用近似基函数和网格技术将无限维的线性矩阵不等式组的求解问题近似为有限维线性矩阵不等式组的求解问题,提出了一种线性矩阵不等式的方法,设计出了相应的[H∞]控制器。最后,通过数值仿真验证了所提方法的有效性。     

T-S模糊系统的基于观测器的H∞控制设计

研究了T-S(Takagi-Sugeno)模糊系统H∞控制设计问题.放宽了Kim E等的T-S模糊 系统可二次稳定的条件.给出了T-S模糊系统新的观测器设计方法.然后给出了T-S模糊系统 基于观测器的H∞控制存在的两个新的充分条件.新方法不但简单,而且充分考虑了模糊子系统 间的相互作用.最后通过例子,应用LMI技术,说明了本文给出的T-S模糊系统的基于观测器 的H∞控制器的设计方法简便易行.     

一类非线性时滞互联系统模糊分散输出反馈控制

对于一类状态不可测非线性互联时滞系统,给出一种基于观测器的模糊分散输出反馈控制方法.首先采用模糊T-S模型对非线性互联时滞系统进行模糊建模,在此基础上给出了模糊分散观测器和基于观测器的模糊分散输出控制器的设计.应用李亚普诺夫函数法和线性矩阵不等式方法给出了模糊分散控制系统稳定的充分条件.仿真结果进一步验证了所提出的模糊分散控制方法的有效性.     

基于改进模糊PID位置随动系统控制

针对直流有刷电机在使用传统模糊PID控制器进行位置随动控制时,由于负载转矩变化导致系统跟随性能下降以及负载转矩未知的问题,提出了基于负载观测器的改进模糊PID控制器代替传统模糊PID控制器,在传统模糊控制结构的基础上增加负载观测器,实时观测系统负载转矩,并利用负载转矩实时调节系统控制器参数,提升了系统在负载转矩突变时的位置跟随能力。仿真结果表明：负载观测器能实时、准确地观测负载转矩,改进模糊PID控制器对负载扰动有较强的抑制能力,并有效减小了系统的调节时间和稳态误差。     

信息物理环境下不确定系统的随机分布式预测控制

针对信息物理系统环境下可能发生的信息丢包问题,提出一种随机分布式预测控制的分析与设计方法.考虑控制器端到执行器端的传输丢包,采用马尔科夫过程对这一丢包过程进行描述.通过对马尔科夫跳变的线性模型进行增广,研究一种具有随机丢包不确定系统的分布式预测控制方法;将系统分解成多个子系统进行描述,研究基于最小最大化优化的分布式预测控制器设计方法,并提出基于迭代交互的子控制器协调算法.将随机分布式预测控制算法在实际电机系统中进行仿真测试,以验证所提出方法的有效性.     

一类非线性对象基于区间观测器的L2增益性能综合

本文针对一类非线性系统,首次考虑了基于区间观测器的L2增益性能控制器设计问题.该控制器的设计主要分两个步骤:首先,设计了该非线性系统的区间观测器,使得观测器系统与原系统之间的误差系统为单调系统;然后,基于该区间观测器系统设计了观测器状态反馈控制律,使得相应的闭环系统为渐近稳定且具有L2增益性能.最后,仿真数例表明了本文所提出方法的有效性.     

带宽受限的CAN总线对数量化调度策略

研究了使用量化技术解决控制器局域网络（CAN）总线网络控制系统的带宽受限问题.首先,建立了多控制回路的网络控制系统模型,该模型综合考虑了采用对数量化器对采样信号进行量化和Bernoulli随机网络丢包过程.并针对量化误差和数据丢包,设计了控制器和观测器使得闭环系统指数均方稳定.然后根据控制性能最优化要求,设计了在带宽受限情况下的反馈网络调度器,提出了量化反馈调度策略.最后通过对3个独立控制回路组成的CAN总线系统进行仿真实验,验证了此调度策略的有效性和可行性.     

具有随机丢包的非线性网络化控制系统鲁棒故障检测

针对具有随机丢包的Lipschitz非线性网络化控制系统,研究了系统存在外部干扰情况下的鲁棒故障检测问题。由于带宽有限,传感器-控制器和控制器-执行器的网络通道中存在随机数据包丢失,鉴于此,设计一种基于观测器的故障检测滤波器,给出存在故障检测滤波器的充分条件,使误差系统均方指数稳定并达到鲁棒H∞干扰抑制水平,同时给出基于观测残差均方值的故障检测策略。通过仿真算例验证了所提出方法的有效性。     

Observer-based H∞ fuzzy control for discrete-time Takagi–Sugeno fuzzy mixed delay systems with random packet losses and multiplicative noises

This paper investigates the observer-based H_∞ fuzzy control problem for a class of discrete-time fuzzy mixed delay systems with random communication packet losses and multiplicative noises, where the mixed delays comprise both discrete time-varying and distributed delays. The random packet losses are described by a Bernoulli distributed white sequence that obeys a conditional probability distribution, and the multiplicative disturbances are in the form of a scalar Gaussian white noise with unit variance. In the presence of mixed delays, random packet losses and multiplicative noises, sufficient conditions for the existence of an observer-based fuzzy feedback controller are derived, such that the closed-loop control system is asymptotically mean-square stable and preserves a guaranteed H_∞ performance. Then a linear matrix inequality approach for designing such an observer-based H_∞ fuzzy controller is presented. Finally, a numerical example is provided to illustrate the effectiveness of the developed theoretical results.     

Robust H∞ Control for Networked Systems With Random Packet Losses

In this paper, the robust Hinfin control problem Is considered for a class of networked systems with random communication packet losses. Because of the limited bandwidth of the channels, such random packet losses could occur, simultaneously, in the communication channels from the sensor to the controller and from the controller to the actuator. The random packet loss is assumed to obey the Bernoulli random binary distribution, and the parameter uncertainties are norm-bounded and enter into both the system and output matrices. In the presence of random packet losses, an observer-based feedback controller is designed to robustly exponentially stabilize the networked system in the sense of mean square and also achieve the prescribed Hinfin disturbance-rejection-attenuation level. Both the stability-analysis and controller-synthesis problems are thoroughly investigated. It is shown that the controller-design problem under consideration is solvable if certain linear matrix inequalities (LMIs) are feasible. A simulation example is exploited to demonstrate the effectiveness of the proposed LMI approach.     

Robust H infinity control for networked systems with random packet losses.

In this paper, the robust H infinity control problem is considered for a class of networked systems with random communication packet losses. Because of the limited bandwidth of the channels, such random packet losses could occur, simultaneously, in the communication channels from the sensor to the controller and from the controller to the actuator. The random packet loss is assumed to obey the Bernoulli random binary distribution, and the parameter uncertainties are norm-bounded and enter into both the system and output matrices. In the presence of random packet losses, an observer-based feedback controller is designed to robustly exponentially stabilize the networked system in the sense of mean square and also achieve the prescribed H infinity disturbance-rejection-attenuation level. Both the stability-analysis and controller-synthesis problems are thoroughly investigated. It is shown that the controller-design problem under consideration is solvable if certain linear matrix inequalities (LMIs) are feasible. A simulation example is exploited to demonstrate the effectiveness of the proposed LMI approach.     

Robust disturbance attenuation for uncertain nonlinear networked control systems

This paper considers the problem of robust disturbance attenuation for a class of uncertain nonlinear networked control systems. Takagi-Sugeno fuzzy models are firstly employed to describe the nonlinear plant. Markov processes are used to model the random network-induced delays and data packet dropouts. The Lyapunov-Razumikhin method has been used to derive such a controller for this class of nonlinear systems such that it is stochastically stabilizable with a disturbance attenuation level. Sufficient conditions for the existence of such a controller are derived in terms of the solvability of bilinear matrix inequalities. An iterative algorithm is proposed to change this non-convex problem into quasi-convex optimization problems, which can be solved effectively by available mathematical tools. The effectiveness of the proposed design methodology is verified by a numerical example.     

Robust Integral Sliding Mode Control of Uncertain Networked Control Systems with Multiple Data Packet Losses

In this paper, a robust integral sliding mode control problem for networked control systems with multiple data packet losses is investigated. The data packet losses occur in both sensor-to-controller and controller-to-actuator channels in a random way and they are modelled by independent Bernoulli binary distributed white sequences. The considered class of system is also subject to matched uncertainties and external disturbances presence. A specific sliding mode surface which take into consideration the stochastic nature of the system is proposed to generate a stable sliding mode dynamics for closed loop system. An integral sliding mode controller is designed to ensure the reachability of the specified sliding mode domain. Finally, simulation results, carried out on a linearized model of cart pendulum system, illustrate the effectiveness of the proposed approach.     

Markov-chain-based output feedback control for stabilization of networked control systems with random time delays and packet losses

This paper proposes an output feedback method to stabilize and control networked control systems (NCSs). Random time delays and packet losses are treated separately when an NCS is modeled. The random time delays in the controller-to-actuator and sensor-to-controller links are modeled with two time-homogeneous Markov chains, while the packet losses are treated by the Dirac delta functions. An asymptotic mean-square stability criterion is established to compensate for the network-induced random time delays and packet losses in both the controller-to-actuator and sensor-to-controller links simultaneously. An algorithm to implement the asymptotic mean-square stability criterion is also proposed. Further, a DC-motor speed-control test bed with Ethernet using User Datagram Protocol (UDP) is constructed and employed for experimental verification. Two sets of experiments, with and without 10% packet losses in the links, are conducted on this NCS. Experimental results illustrate the effectiveness of the proposed output feedback method compared to conventional controllers. This method could compensate for the effects of the random time delays and packet losses and guarantee the system performance and stability. The integral time and absolute error (ITAE) of the experiments without packet losses is reduced by 13% with the proposed method, and the ITAE of experiments with 10% packet losses, by 30%. The NCS can track the reference command faithfully with the proposed method when random time delays and packet losses exist in the links, whereas the NCS fails to track the reference command with the conventional control algorithms.     

Robust exponential stability of uncertain stochastic systems with probabilistic time‐varying delays

This paper is concerned with the problem of delay‐distribution–dependent robust exponential stability for uncertain stochastic systems with probabilistic time‐varying delays. Firstly, inspired by a class of networked systems with quantization and packet losses, we study the stabilization problem for a class of network‐based uncertain stochastic systems with probabilistic time‐varying delays. Secondly, an equivalent model of the resulting closed‐loop network‐based uncertain stochastic system is constructed. Different from the previous works, the proposed equivalent system model enables the controller design of the network‐based uncertain stochastic systems to enjoy the advantage of probability distribution characteristic of packet losses. Thirdly, by applying the Lyapunov‐Krasovskii functional approach and the stochastic stability theory, delay‐distribution–dependent robust exponential mean‐square stability criteria are derived, and the sufficient conditions for the design of the delay‐distribution–dependent controller are then proposed to guarantee the stability of the resulting system. Finally, a case study is given to show the effectiveness of the results derived. Moreover, the allowable upper bound of consecutive packet losses will be larger in the case that the probability distribution characteristic of packet losses is taken into consideration.     

Robust ℋ︁∞ sliding mode control for nonlinear stochastic systems with multiple data packet losses

In this paper, an ??_∞ sliding mode control (SMC) problem is studied for a class of discrete‐time nonlinear stochastic systems with multiple data packet losses. The phenomenon of data packet losses, which is assumed to occur in a random way, is taken into consideration in the process of data transmission through both the state‐feedback loop and the measurement output. The probability for the data packet loss for each individual state variable is governed by a corresponding individual random variable satisfying a certain probabilistic distribution over the interval [0 1]. The discrete‐time system considered is also subject to norm‐bounded parameter uncertainties and external nonlinear disturbances, which enter the system state equation in both matched and unmatched ways. A novel stochastic discrete‐time switching function is proposed to facilitate the sliding mode controller design. Sufficient conditions are derived by means of the linear matrix inequality (LMI) approach. It is shown that the system dynamics in the specified sliding surface is exponentially stable in the mean square with a prescribed ??_∞ noise attenuation level if an LMI with an equality constraint is feasible. A discrete‐time SMC controller is designed capable of guaranteeing the discrete‐time sliding mode reaching condition of the specified sliding surface with probability 1. Finally, a simulation example is given to show the effectiveness of the proposed method. Copyright © 2011 John Wiley & Sons, Ltd.     

网络控制系统动态量化H∞控制

基于线性矩阵不等式技术,采用状态反馈控制,考虑同时带有网络诱导随机丢包 和量化的H∞控制问题。考虑信号经网络从传感器到控制器和从控制器到执行器的传输中存在 通信诱导随机丢包,并采用动态量化器量化信号。设计H∞控制器的同时,提出量化的控制策 略,使得闭环系统在量化器的量化范围条件下指数均方稳定且具有指定的H∞性能指标。通过 数值仿真例子表明设计方法的有效性。