Data-based predictive control for networked nonlinear systems with packet dropout and measurement noise

In this paper, the data-based control problem is investigated for a class of networked nonlinear systems with measurement noise as well as packet dropouts in the feedback and forward channels. The measurement noise and the number of consecutive packet dropouts in both channels are assumed to be random but bounded. A data-based networked predictive control method is proposed, in which a sequence of control increment predictions are calculated in the controller based on the measured output error, and based on the control increment predictions received by the actuator, a proper control action is obtained and applied to the plant according to the real-time number of consecutive packet dropouts at each sampling instant. Then the stability analysis is performed for the networked closedloop system. Finally, the effectiveness of the proposed method is illustrated by a numerical example.     

遥操作系统带观测器的反馈控制

针对力觉临场感遥操作机器人系统传输通道中存在通讯时延，造成系统不稳定和操作性能降低等问题，提出了用时间前向观测器预测从手状态，用力、位置和速度反馈消除或减小时延对系统影响的方法，并对系统的稳定性和透明性进行了分析。实验结果表明了该方法的有效性。     

随机时延网络控制系统的鲁棒H∞状态反馈控制

研究了含有双随机时延的不确定网络控制系统的鲁棒H_∞状态反馈控制问题。将传感器到控制器和控制器到执行器的网络时延建模为相互独立的连续时间离散状态的马尔可夫随机过程。基于此网络环境,构造时延依赖的控制器,将不确定网络控制系统转化为马尔可夫跳变系统。通过Lyapunov Krasovskii泛函方法和新的矩阵不等式技术,给出了系统随机稳定且满足H_∞性能的充分条件,并以矩阵不等式形式给出了相应的控制器设计方法。最后,给出了仿真算例,验证了该方法的有效性。     

对丢失数据包的网络控制系统的分析及最优控制

针对同时存在前向通道和反馈通道数据包丢失的离散时间系统,分别将数据包丢失作为独立的贝努利过程进行建模。通过对量化器量化水平参数的约束条件,确保状态估计在均方差意义下的稳定,并基于约束条件获得前向通道的最大丢包率的一个上界。与此同时,基于线性二次型最优控制(LQG)性能指标和状态估计,给出了具有数据包丢失的系统最优控制律,运用线性矩阵不等式(LMI)技术和二分法进行优化设计,并给出了反馈通道最大丢包率的一个优化算法。最后通过仿真实例验证了理论结果。     

Packet-loss-dependent stabilization of NCSs with network-induced delay and packet dropout

This paper is concerned with controller design of networked control systems (NCSs) with both network-induced delay and arbitrary packet dropout.By using a packet-loss-dependent Lyapunov function,suffic...     

Ho∞-based fault detection for nonlinear networked systems with random packet dropout and probabilistic interval delay

The fault detection problem for the nonlinear networked control system (NCS) with packet dropout and delay is investigated.A nonlinear stochastic system model is proposed to account for the NCS with random packet dropout and networkinduced non-uniformly distributed time-varying delay in both from sensor to controller (S/C) and from controller to actuator (C/A).Based on the obtained NCS model,employing an observer-based fault detection filter as the residual generator,the addressed fault detection problem is converted into an auxiliary nonlinear H∞ control problem.Then,with the help of Lyapunov functional approach,a sufficient condition for the desired fault detection filter is constructed in terms of certain linear matrix inequalities,which depend on not only the delay interval but also the delay interval occurrence rate and successful packet communication rate.Especially,a trade-off phenomenon between the maximum allowable delay bound and successful data packet transmission rate is found,which is typically resulted from the limited bandwidth of communication networks.The effectiveness of the proposed method is demonstrated by a simulation example.     

Robust H∞ control for networked control systems

The robust H∞ control for networked control systems with both stochastic network-induced delay and data packet dropout is studied.When data are transmitted over network,the stochastic data packet dropout process can be described by a two-state Markov chain.The networked control systems with stochastic network-induced delay and data packet dropout are modeled as a discrete time Markov jump linear system with two operation modes.The sufficient condition of robust H∞ control for networked control systems stabilized by state feedback controller is presented in terms of linear matrix inequality.The state feedback controller can be constructed via the solution of a set of linear matrix inequalities.An example is given to verify the effectiveness of the method proposed.     

有时延和数据包丢失的网络控制系统反馈控制

针对同时具有网络诱导时延和数据包丢失的网络控制系统,假设数据包丢失率一定,网络诱导时延小于一个采样周期,将网络控制系统建模为具有事件率约束的异步动态系统。提出了使得该系统达到指数稳定的动态输出反馈控制器的设计方法。利用遗传算法获得了NCS的事件衰减率的局部极大值。通过仿真算例证明了该方法的有效性。     

Stabilization of Continuous-Time Systems Against Stochastic Network Uncertainties: Fundamental Variance Bounds

This paper studies the stabilizability and stabilization of continuous-time systems in the presence of stochastic multiplicative uncertainties. The authors consider multi-input, multi-output(MIMO) linear time-invariant systems subject to multiple static, structured stochastic uncertainties,and seek to derive fundamental conditions to ensure that a system can be stabilized under a mean-square criterion. In the stochastic control framework, this problem can be considered as one of optimal control under state-or input-dependent random noises, while in the networked control setting, a problem of networked feedback stabilization over lossy communication channels. The authors adopt a mean-square small gain analysis approach, and obtain necessary and sufficient conditions for a system to be meansquare stabilizable via output feedback. For single-input, single-output(SISO) systems, the condition provides an analytical bound, demonstrating explicitly how plant unstable poles, nonminimum phase zeros, and time delay may impose a limit on the uncertainty variance required for mean-square stabilization. For MIMO minimum phase systems with possible delays, the condition amounts to solving a generalized eigenvalue problem, readily solvable using linear matrix inequality optimization techniques.     

数据丢包的参数不确定下无人机滚动时域估计

针对网络中通信链路中断及系统参数不确定现象,研究了数据包丢失的参数不确定无人机系统状态估计问题,基于滚动时域估计理论和随机最小二乘理论,提出了一种分布式滚动时域估计算法。对于数据包丢失和参数不确定问题,采用已知概率的马尔可夫序列和系统矩阵扰动噪声进行建模。仿真结果表明,该算法的估计效果优于一种新的卡尔曼滤波算法。最后,研究分析了系统压缩量、数据包接收概率和时窗长度对所提算法估计性能的影响。在系统不确定性和丢包概率未知的情况下,适当增加时窗长度可以提高算法估计性能。     

Robust H∞ control for networked control systems

The robust H∞ control for networked control systems with both stochastic network-induced delay and data packet dropout is studied. When data are transmitted over network, the stochastic data packet dropout process can be described by a two-state Markov chain. The networked control systems with stochastic network-induced delay and data packet dropout are modeled as a discrete time Markov jump linear system with two operation modes. The sufficient condition of robust H∞ control for networked control systems stabilized by state feedback controller is presented in terms of linear matrix inequality. The state feedback controller can be constructed via the solution of a set of linear matrix inequalities. An example is given to verify the effectiveness of the method proposed.     

Fault detection for networked systems subject to access constraints and packet dropouts

This paper addresses the problem of fault detection(FD) for networked systems with access constraints and packet dropouts.Two independent Markov chains are used to describe the sequences of channels which are available for communication at an instant and the packet dropout process,respectively.Performance indexes H∞ and H_ are introduced to describe the robustness of residual against external disturbances and sensitivity of residual to faults,respectively.By using a mode-dependent fault detection filter(FDF) as residual generator,the addressed FD problem is converted into an auxiliary filter design problem with the above index constraints.A sufficient condition for the existence of the FDF is derived in terms of certain linear matrix inequalities(LMIs).When these LMIs are feasible,the explicit expression of the desired FDF can also be characterized.A numerical example is exploited to show the usefulness of the proposed results.     

Tracking Control of Wheeled Mobile Robots with Communication Delay and Data Loss

This paper considers the tracking control problem of a wheeled mobile robot under situation of communication delay and consecutive data packet dropouts in the feedback channel. A tracking controller in discrete-time domain for the case of ideal network condition is first derived, and then the networked predictive controller as well as two algorithms for dealing with communication delay and consecutive data packet dropouts are proposed. Simulation and experimental results verify the realizability and effectiveness of the proposed algorithms.     

基于ECN算法的无线QoS实时视频传输方案

针对无线局域网,提出了一种基于RTP/RTCP协议下MPEG-4标准的多路实时视频流的具体实现方案,提出了一种有效的基于时间戳的多路视频同步模型。针对无线QoS机制,系统应用了一种基于RTCP反馈友好码率控制算法TFRC的ECN算法,根据ECN标记包率来动态调整发送码率实现拥塞控制。实验表明该传输方案能获得较好的视频传输质量。     

Internet-based event synchronization communication driven telerobotics

1.INTRODUCTION Teleoperationmakeshumansensetoremotesiteand byitmanyapplicationcanbeappliedintoreality.A longdistanceteleoperationmayhavemuchmore meaningtopeople.Throughspace,sea,andnet work,teleoperationshowsitscharm.Whenrobotis inducedinteleoperationastheexecutoritisnamedas telerobotics.NowInternetisprevalentintheworld,overitconstructingateleroboticshasmuchmoread vantagethanothers,likeconstructingeasily,cheap costandmaintenanceconvenientlyetc.Butthereare alsosomedrawbacksinit,liketimede…     

线性不确定系统的鲁棒容错H∞控制设计

研究了线性不确定系统的鲁棒容错H∞控制问题.当系统既有状态滞后,又有控制输入滞后,而且状态和控制输入的不确定项均满足匹配条件时,运用线性矩阵不等式(LMI)方法,提出了一种针对不确定系统的鲁棒容错反馈控制设计方法.利用该方法设计的闭环系统,不仅在传感器发生故障时具有完整性,而且对于系统的参数不确定性具有鲁棒性.以设计实例及仿真结果验证了这种方法的有效性.     

具有异步时延的网络化控制系统故障检测

针对具有异步信号时延的离散系统，研究了在异步时延下基于观测器的故障检测及其设计问题。首先提出了一个存在异步时延下系统的故障检测模型，该模型保持了系统的定常性和时不主特性。同时在此模型上构造了异步时延系统的状态观测器，并依据系统观测误差通过合理地选择湮灭加权矩阵的方法构建了频域内的故障检测残差发生器。最后通过一个摆式列车试验模型的仿真检验了设计方法的有效性。     

Model Reference Adaptive Control for Networked Distributed Systems with Strong Interconnections and Communication Delays

In recent years, networked distributed control systems (NDCS) have received research attention. Two of the main challenges that such systems face are possible delays in the communication network and the effect of strong interconnections between agents. This paper considers an NDCS that has delays in the communication network, as well as strong interconnections between its agents. The control objective is to make each agent track efficiently a reference model by attenuating the effect of strong interconnections via feedback based on the delayed information. First, the authors assume that each agent knows its own dynamics, as well as the interconnection parameters, but receives information about the states of its neighbors with some communication delay. The authors propose a distributed control scheme and prove that if the interconnections can be weakened and if the communication delays are small enough, then the proposed scheme guarantees that the tracking error of each agent is bounded with a bound that depends on the size of the weakened interconnections and delays, and reduces to zero as these uncertainties reduce to zero. The authors then consider a more realistic situation where the interconnections between agents are unknown despite the cooperation and sharing of state information. For this case the authors propose a distributed adaptive control scheme and prove that the proposed scheme guarantees that the tracking errors are bounded and small in the mean square sense with respect to the size of the weakened interconnections and delays, provided the weakened interconnections and time delays are small enough. The authors then consider the case that each agent knows neither its dynamics nor the interconnection matrices. For this case the authors propose a distributed adaptive control scheme and prove that the proposed scheme guarantees that the tracking errors are bounded and small in the mean square sense provided the weakened interconnections and time delays are small enough. Finally, the authors present an illustrative example to present the applicability and effectiveness of the proposed schemes.     

有数据包丢失的网络控制系统H∞状态反馈控制

研究了有数据包丢失的网络控制系统H∞状态反馈控制问题。考虑网络控制系统中存在数据包丢失的情况,丢包过程建模为有限状态的马尔可夫过程。在此模型的基础上,利用马尔可夫跳变线性系统的理论和线性矩阵不等式方法,给出了保持系统均方稳定且满足H∞性能的控制器存在的充分条件,并给出了相应的控制器设计方法。最后数例仿真结果表明了控制器设计方法的有效性。     

含有通信时滞的多航天器SO(3)姿态协同控制

针对多航天器系统姿态协同问题,提出了存在通信时滞情形下基于特殊正交群SO(3)的协同控制设计方法。采用SO(3)对姿态进行统一描述,并结合有向通信拓扑对协同控制系统进行建模。在此基础上设计了旋转矩阵形式的协同指令,定义SO(3)上的协同误差以构造协同控制器。引入补偿滤波器对系统的时滞状态进行补偿,从理论上对设计的SO(3)协同控制器进行了稳定性分析和证明,保证了对指令信号的有效跟踪,从而实现航天器之间的姿态协同。通过仿真对所提方法进行了验证,仿真结果表明,所提出的基于SO(3)的姿态协同控制方法是可行、有效的。