不确定时滞网络控制系统的状态反馈控制

在网络传输过程中, 系统的稳定性受不确定, 网络延迟, 丢包和错序所影响. 本文针对这些非理想网络状况,研究了网络控制系统状态反馈控制. 建立连续时间系统模型时, 还引入了一个定常状态时延, 使得模型更贴近实际.随后, 运用改进的Lyapunov-Krasovskii函数, 推导出网络控制系统鲁棒稳定的充分条件, 并基于该充分条件得到利用线性矩阵不等式(LMI)的控制器设计方法, 再运用迭代算法求解相关系数. 最后通过MATLAB数值仿真算例, 证明了本文方法的正确性和有效性.     

具有时延和数据包丢失的网络控制系统稳定性

针对单数据包传输情况,将同时存在网络诱导时延和数据包丢失的网络控制系统建模为具有事件约束的异步动态系统,依据Lyapunov稳定性原理,提出了同时存在网络诱导时延和数据包丢失的网络控制系统指数稳定的网络诱导时延条件和数据包丢失条件,对条件进行了实例仿真验证,仿真结果表明该条件是有效的.     

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。     

具有随机丢包的一类网络控制系统的故障检测

针对存在随机数据包丢失的网络环境,研究了一类网络控制系统的故障检测问题.考虑随机丢包同时发生在传感器与控制器以及控制器与执行器之间,将网络控制系统建模为含有4个模态的马尔可夫跳变线性系统.基于此类模型,构造了系统的残差发生器,相应的故障检测问题转化为H∞滤波问题.利用马尔可夫跳变线性系统理论,设计了故障检测滤波器,使得...     

网络控制系统稳定性研究

综述了目前网络控制系统的研究现状,介绍了随机延迟问题、数据包丢失问题和多通道输出问题的建模以及各种控制策略.在此基础上,分析了网络控制系统稳定性研究中尚待解决的问题以及一些新的研究方向.     

Finite-time boundedness and stabilisation of networked control systems with bounded packet dropout

In this paper, the finite-time boundedness and stabilisation problems of a class of networked control systems (NCSs) with bounded packet dropout are investigated. The main results provided in the paper are sufficient conditions for finite-time boundedness and stability via state feedback. An iterative approach is proposed to model NCSs with bounded packet dropout as jump linear systems (JLSs). Based on Lyapunov stability theory and JLSs theory, the sufficient conditions for finite-time boundedness and stabilisation of the underlying systems are derived via linear matrix inequalities (LMIs) formulation. Moreover, both sensor-to-controller and controller-to-actuator packet dropouts are considered simultaneously. Lastly, an illustrative example is given to demonstrate the effectiveness of the proposed results.     

Modelling and control of Zigbee-based wireless networked control system with both network-induced delay and packet dropout

A new stochastic switched linear model is established to describe the Zigbee-based wireless networked control system (WNCS) with both network-induced delay and packet dropout. The network-induced delay can be less or longer than one sampling period. A sufficient condition is presented for the exponentially mean square stability of the closed-loop WNCS, and corresponding state feedback controller is designed by using the augmenting technique and multi-Lyapunov approach. Then, combined with carrier sense multiple access with collision avoidance (CSMA-CA) algorithm, a method is given to choose proper parameter values. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed method.     

Optimal controller location in wireless networked control systems

The control performance of wireless networked control systems (WNCS) has been shown to heavily depend on the packet delivery quality of both the sensor‐to‐controller and controller‐to‐actuator communications. Such quality relies on the relative distance between the wireless transmitter and receiver, which naturally raises the challenging problem of controller placement in WNCS for optimal control performance. In this paper, we investigate the optimal controller location (OCL) problem in WNCS based on linear‐quadratic‐Gaussian control strategy. For the one‐hop network case where the controller can only be placed at either the sensor side or the actuator side, we derive a simple yet effective criterion to determine the OCL. For the more general multi‐hop case where the controller can be located at either one of the sensors, relays, or actuators, we obtain the necessary and sufficient condition under which the closed‐loop system is guaranteed to be stable. On the basis of these results, we further transform the OCL problem into an optimization problem that can be solved efficiently. Numerical results are provided to verify our analysis. Copyright © 2013 John Wiley & Sons, Ltd.     

Time delay and packet dropout compensation for networked control systems: a linear estimation method

This article studies the problem of H _∞ controller design for networked control systems (NCSs) with time delay and packet dropout. A linear estimation-based time delay and packet dropout compensation method is proposed. The delay switching-based method is presented to deal with the variation of time delay, and H _∞ controller design is presented for NCSs with packet dropout compensation by using linear matrix inequality (LMI)-based method. Then the combined delay switching and parameter uncertainty-based method is presented to model the variation of time delay, and H _∞ controller design is also presented. The simulation results illustrate the effectiveness of the newly proposed linear estimation-based time delay and packet dropout compensation.     

Output‐feedback‐based sliding mode control for networked control systems subject to packet loss and quantization

In this paper, observer‐based sliding mode control is considered for networked control systems subject to quantization, in which packet dropout may happen when the measurement output is transmitted from the sensor to the controller. Firstly, a compensating scheme is proposed to deal with the effect of packet loss modelled as a Bernoulli process. Then, by means of available output information and state observer, the desirable sliding mode controller is designed. Furthermore, both the reachability and the stochastic stability of sliding mode dynamics can be attained and the corresponding sufficient conditions are derived. Finally, numerical simulation results are provided to illustrate the proposed control law.     

网络控制系统的滑模多步预估控制

针对网络控制系统中出现的长时滞、网络诱导噪声和数据包丢失,提出了的滑模多步预估控制器的设计方法.首先对提出的控制器进行了描述,它利用滑模控制的强鲁棒性来克服网络诱导噪声,采用多步预估的办法来处理网络中的时滞和数据包丢失.进而对导出的闭环网络控制系统的稳定性进行了分析.最后对通过网络控制的直流电机,采用所提出的方法设计了控制器,仿真结果验证了方法的有效性.     

无线网络控制系统研究现状及方向

从基于无线传感器网络理论的无线网络控制系统的工业应用、控制方法设计、调度策略和通信协议的设计以及控制与调度协同设计等方面阐述了目前无线网络控制系统的主要研究内容和研究现状,并讨论了今后无线网络控制系统的研究方向。     

网络控制系统的H∞状态反馈控制器设计

研究了对网络控制系统如何设计H∞状态反馈控制器.这些网络控制系统中存在不确定的网络时延和数据包丢失.当网络时延和连续丢包有界时,可以将系统建模为具有时变输入时滞的系统,利用Lyapunov-Krasovskii泛函,推导出网络控制系统渐近稳定的充分条件.将这些充分条件转化为带等式约束的LMIs,并对他们进行迭代求解,就可以构造H∞控制器.与现有结果相比,在推导稳定性条件时本文对交叉项采取了更紧的界定,并且在设计控制器时无需知道调节参数.因此,本文提出的方法具有更低的保守性.仿真结果说明了本方法的正确性和有效性.     

Control for wireless networked control systems based on 802.11b

In this article, the stabilisation problem is considered for a wireless networked control system. A new model is constructed by integrating the wireless network protocols in IEEE802.11 with control systems. All the possible delays and dropouts are considered in the new model for the packets to be transmitted on both the sensor-to-controller side and the controller-to-actuator side of the WNCS structure. A linear state feedback controller is designed to stabilise the model. The results are given in the form of linear matrix inequalities. Finally, simulations are performed to show the effectiveness of the proposed method.     

存在时延和数据包丢失的网络控制系统故障检测

考虑一类长时延网络控制系统,在假定其存在控制时延和数据包丢失的基础上对其进行故障检测．首先对系统进行建模,将故障观测器构建成随机时延切换系统模型;然后通过李雅普诺夫稳定性理论,将观测器系统的均方渐近稳定条件归结为一线性矩阵不等式,当系统正常时,若给定的矩阵不等式成立,则该观测器是渐近稳定的,当系统发生故障时,观测器残差...     

通信受限网络控制系统的H∞ 控制

针对一类通信受限的网络控制系统,研究其随机稳定性和 ∞控制问题.考虑到系统存在随机丢包、时延、对数量化和概率传感器故障等因素,提出一种新的网络控制系统模型.基于Lyapunov稳定性理论,得到了系统随机稳定性的充分条件,并利用线性矩阵不等式技术,给出了系统 ∞控制器的设计方法.数值仿真算例验证了所得结论的有效性.     

具有长时延和丢包的网络控制系统的故障检测

针对同时具有网络诱导时延和数据包丢失的异步时钟网络控制系统,假设数据包丢失率一定,网络诱导时延大于一个采样周期,根据执行器接收数据包的情况,设计了系统的故障观测器,将其建模为具有事件率约束的异步动态系统,基于该模型进行了稳定性分析,当条件满足时,整个系统是指数稳定的。在此基础上研究了系统的故障检测,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。仿真示例验证了所提出方法的有效性。     

网络化控制系统故障检测技术的最新进展

伴随着控制系统的日益复杂化以及网络技术的飞速发展, 网络化控制系统受到了人们越来越多的关注. 而作为提高系统安全性和可靠性的一项重要技术, 故障检测逐渐成为控制领域的研究热点之一. 本文针对网络化控制系统中存在的各种典型问题, 综述了相应故障检测技术的最新进展.     

具有快变时延和丢包的网络控制系统镇定

对一类网络控制系统,研究了变时延和数据丢包对闭环系统稳定性的影响.基于Lyapunov-Krasovskii方法,给出了闭环系统的稳定条件,该条件不依赖于时延变化率的上界.通过求解一个适当的线性矩阵不等式(LMI)得到控制增益矩阵,求解时不需要对矩阵的结构进行限制,也不必使用重复迭代.最后,给出了一个数值例子以说明方法的有效性.     

Fault detection for networked control systems subject to quantisation and packet dropout

This article addresses the stochastic fault detection (SFD) problem in finite-frequency domain for a class of networked control systems (NCSs) with respect to signal quantisation and data packet dropout. Considering a logarithmic quantiser and Markovian packet dropout, the NCS is modelled as a Markov jump linear system (MJLS) with quantisation error. Further, a new definition of finite-frequency stochastic H _? index is given, which gives a measurement of sensitivity. Subsequently, sufficient conditions are derived to guarantee that the MJLS can achieve such a performance. By virtue of the obtained conditions, the fault detection filters (FDFs) are designed in finite-frequency domain, which are valid in characterising the disturbance attenuation performance and finite-frequency fault sensitivity performance. Finally, a simulation example is given to illustrate the method and its effectiveness.