非线性时延网络控制系统的模糊建模与控制

针对时变网络诱导时延小于一个采样周期的非线性时延网络控制系统,讨论系统的稳定性及控制器的设计方法.利用基于“IF-THEN”规则的模糊模型近似系统中的非线性,将时延的不确定性转化为系统参数的不确定性,从而将此类非线性网络控制系统建模为一类具有参数不确定性的离散Takagi-Sugeno（T-S）模糊模型.基于建立的模型,利用Lyapunov方法和线性矩阵不等式方法,分析了系统的稳定性及模糊状态反馈控制器的设计方法,最后通过仿真实例验证了所提出方法的有效性.     

基于U模型的网络控制系统时延补偿研究

针对网络控制系统非线性问题解决方法少的情况,引入U模型方法进行被控对象建模,降低时延故障对网络控制系统造成的影响,结合广义预测控制(GPC)算法和PI控制器反馈结构,提出基于U模型的改进PI型广义预测控制方法 U-PIGPC。然后结合改进SSA-BP时延预测器,设计基于SSA-BP和U-PIGPC的网络控制系统时延补偿控制器。通过仿真对比验证了U-PIGPC补偿控制的性能优于GPC和U-GPC,其超调量更小,反应速度更快,具有更好的时延补偿控制效果。     

时延网络控制系统保性能控制器的设计

本文讨论了一类不确定性时延网络控制系统保性能控制器的设计问题,首先把网络控制系统建模为一类具有不确定性的离散时延系统,利用Lyapunov稳定性理论,讨论了系统的稳定性,结合一个二次型性能指标,推导出了保性能控制器的存在性.     

长时延和丢包的网络控制系统保性能控制

为了研究具有长时延和丢包的网络控制系统保性能控制问题,假设传感器由时钟驱动,控制器和执行器由事件驱动,网络时延在两个采样周期之间,丢包具有马尔科夫跳变特性,利用状态增广的方法,把具有长时延和丢包的网络控制系统建模为具有两种运行模式的离散时间马尔可夫跳变系统,把网络时延转化为系统参数矩阵的不确定性.在此基础上,利用马尔可夫线性跳变系统理论和线性矩阵不等式方法,推导出使网络控制系统随机稳定的保性能控制律存在的充分条件,并给出了设计方法.数例仿真说明了所用方法的有效性.     

基于HTCPN和隐马尔科夫的网络控制系统模型分析

针对具有随机时延的网络控制系统(NCSs),研究其建模与系统分析问题.运用层次时间颜色Petri网(HTCPN)对以PLC为控制器的NCSs进行结构保留形式建模,并以新颖的方式将网络丢包和乱序现象与系统模型结合.重点分析系统中传感器-控制器、控制器-执行器随机时延分布情况,建立时延与网络中数据包运行情况间的关系.在此基础上,利用Baum-Welch算法建立两种时延的隐马尔科夫模型(HMM),进一步验证了HTCPN模型与HMM的等效性.     

无线网络环境下移动机器人的控制策略研究

在移动机器人控制性能优化的研究中,针对无线控制网络中存在时延的情况,进行了控制器与补偿器的研究与设计.首先建立了移动机器人动力学模型,并针对模型设计离散反演控制器使移动机器人能够对给定信号进行跟踪.引入无线网络,进而分析网络时延对无线网络控制系统性能的影响,并针对网络时延利用预测控制算法设计控制序列预测补偿器,从而完成在时延存在的情况下仍然可以对移动机器人进行准确控制的无线移动机器人控制系统.仿真结果表明,设计的控制器与补偿器为无线网络环境下移动机器人的控制性能优化提供了参考.     

网络控制系统H∞鲁棒控制器设计

针对存在不确定时延的网络控制系统, 将未知扰动和建模误差转换为满足给定约束的矩阵, 建立具有参数不确定性的网络控制系统模型。基于Lyapunov稳定性理论证明控制系统渐近稳定, 结合线性矩阵不等式完成H∞鲁棒控制器设计。通过仿真实验, 比较在不同时延条件下系统的状态响应曲线, 结果证明所设计的H∞鲁棒控制器可以解决系统中存在不确定建模误差、干扰和时延等问题, 具有一定的鲁棒性。     

网络控制系统的时延仿真研究与控制器设计

针对网络控制系统(NCS)中的随机时延问题,根据实际网络时延的分布情况,提出了一种新的具有随机时延的网络控制系统的建模方法-离散T-S模型,并用并行分布补偿原理(PDC)设计模糊控制器.同时提出一种新的模糊控制系统隶属函数的确定方法,利用Lyapunov定理和线性矩阵不等式(LMI)研究了系统的稳定性问题,给出基于LMI的模糊控制器的设计方法.最后通过仿真实例证明控制方法能够使具有时延的网络控制系统稳定.     

网络控制系统的模型建立及稳定研究

随着互联网技术的发展,以太网逐渐被引入到工业控制领域.对于一个网络控制系统,网络带来的控制系统时滞和丢包是不可避免的,因此,在对网络控制系统的建模中,必需重点考虑时延和丢包的影响.分析了网络控制系统的时延特征,并将数据丢包的网络控制系统建模成具有事件率约束的异步动态系统.对网络控制系统模型用传统的PID算法对系统进行仿真控制,在存在系统随机时延和不存在随机时延的两种情况下,仿真分析了网络控制系统的稳定性,仿真结果进一步验证了网络控制系统保持稳定的丢包范围.     

基于动态反馈控制器的网络控制系统的稳定性分析

考虑实际模型的不确定性,针对一类具有不确定线性参数的网络控制系统,给出具有网络诱导时延及不确定线性参数的被控对象模型,设计其动态反馈控制器,建立基于动态反馈控制器的网络控制系统闭环模型.采用Lyapunov方法,给出保证该系统稳定的最大允许时延上界.仿真结果表明系统模型及控制器设计的合理性,所得最大允许时延上界保守性更弱.     

Smith predictor design for robust performance

A method is outlined for designing Smith predictor controllers that provide robust performance despite real parameter uncertainties in the process model. Insight into the design process is gained by viewing the Smith predictor from the perspective of internal model control. Performance requirements are written in terms of a frequency-domain weight restricting the magnitude of the closed-loop sensitivity function. A general method for approximating multiple parameter uncertainties by a single multiplicative uncertainty is developed—an exact bound is derived for the magnitude of multiplicative uncertainty used to approximate simultaneous uncertainties in process gain, time-constant, and time-delay. Three different tuning methods are demonstrated; each is applied to a wide range of parameter uncertainties in a first-order with time-delay model. The first tuning method locates loop transfer-function uncertainty regions to test for robust performance—real parameter uncertainties are considered exactly. The second tuning method approximates real parameter uncertainties by multiplicative uncertainty and uses structured singular value analysis to guarantee robust performance. The third is a ‘quick design’ method that considers the unit magnitude crossing of the multiplicative uncertainty. Finally, the Smith predictor controller is compared with the structured-singular-value-optimal controller.     

线性离散时滞系统的鲁棒耗散控制

考虑线性离散时滞系统的二次型耗散控制问题.对于确定系统,给出渐近稳定且严格二次型耗散的条件和动态输出反馈控制器使闭环系统渐近稳定且严格二次型耗散.对于不确定系统,考虑不确定性具有耗散特性的情形,讨论鲁棒耗散性分析和动态输出反馈鲁棒耗散控制问题.通过构造增广系统,将不确定系统的鲁棒严格二次型耗散分析和设计转化为确定系统的情况.所得结果为离散时滞系统的无源控制和H∞控制提供了统一框架,且为离散时滞系统的分析和设计提供了一种更灵活、保守性更小的方法.     

时滞系统的云模型智能控制

该文利用云模型控制规则的不确定性推理,采用模糊控制原理,设计出了混合维的云模型智能控制器,对工业过程中常见的时滞模型进行了仿真实验。仿真结果表明,该控制器简易、直观、鲁棒性强,具有良好的控制性能和较好的应用价值。     

不确定时滞系统的鲁棒耗散控制

耗散不确定性是已经被广泛讨论的范数有界的不确定性和正实不确定性的广义化,因此,从二次型供给率的角度,将耗散不确定性引入线性时变时滞系统,研究了含有此类不确定性的线性时滞系统的鲁棒耗散控制问题,给出了线性矩阵不等式（LMI）形式的充分条件。而且,考虑了不确定时滞系统在状态反馈控制器作用下的闭环系统的耗散控制问题,同样给出了LMI形式的充分条件,并通过线性矩阵不等式的可行解构造出鲁棒耗散的状态反馈控制器。最后。通过实例证明了定理的可行性。     

Sliding-mode control of uncertain systems in the presence of unmatched disturbances with applications

This article considers the development of constructive sliding-mode control strategies based on measured output information only for linear, time-delay systems with bounded disturbances that are not necessarily matched. The novel feature of the method is that linear matrix inequalities are derived to compute solutions to both the existence problem and the finite time reachability problem that minimise the ultimate bound of the reduced-order sliding-mode dynamics in the presence of state time-varying delay and unmatched disturbances. The methodology provides guarantees on the level of closed-loop performance that will be achieved by uncertain systems which experience delay. The methodology is also shown to facilitate sliding-mode controller design for systems with polytopic uncertainties, where the uncertainty may appear in all blocks of the system matrices. A time-delay model with polytopic uncertainties from the literature provides a tutorial example of the proposed method. A case study involving the practical application of the design methodology in the area of autonomous vehicle control is also presented.     

Reduction-based robust active queue management control

This paper is concerned with the design of improved active queue management (AQM) control schemes for time-delay systems taking into account explicitly the presence of delays in the controller design. A robust controller coping with uncertainties on the network parameters such as round-trip time and load variations is proposed. This is based on an appropriate robust reduction method for time-delay systems. A robust observer for time-delay systems is used to estimate online the average transmission window resulting in a robust output feedback stabilization scheme for AQM. The resulting control law is validated and tested firstly through numerical simulations and then pseudo-experimentally by network simulator (NS-2).     

Saturating composite disturbance-observer-based control and H ∞ control for discrete time-delay systems with nonlinearity

This note is concerned with a saturating composite disturbance-observer-based control (DOBC) and H _∞ control for a class of discrete time-delay systems with nonlinearity and disturbances. The disturbances are supposed to include two parts. One in the input channel is generated by an exogenous system with uncertainty, which can represent the harmonic signals with modeling perturbations. The other is supposed to have the bounded H ₂ norm, which can represent parametric uncertainties and external disturbance existing in the controlled object. The design approaches of reduced-order disturbance observer are presented for the estimation of the disturbance. By composite control law with saturation, the disturbances can be rejected and attenuated, simultaneously, the desired dynamic performances can be guaranteed for discrete time-delay systems with known and unknown nonlinear dynamics, respectively. Simulation for a flight control system is provided to show the effectiveness of the proposed scheme compared with the previous schemes.     

Impulsive controller design for singular networked control systems with packet dropouts

This paper considers the problem of impulsive time-delay control for singular networked impulsive control systems(SNICSs) and uncertain SNICSs both with network-induced delay and packet dropouts. The parameter uncertainty is assumed to be norm bounded. The problem to be addressed is the design of robust impulsive time-delay feedback controllers such that the exponential stability of the resulting closed-loop system is guaranteed for admissible uncertainties. By applying Lyapunov function theory and Halanay Lemma, impulsive time-delay controller is derived through solving LMIs. Numerical examples are provided to demonstrate the application of the proposed method.     

Robust adaptive neural tracking control for a class of electrically driven robots with time delays

This article addresses the problem of designing the robust tracking control for a class of uncertain electrically driven robots with time delays. The unknown time-delay uncertainty is assumed to be bounded by a function of all the state variables. By suitably choosing the Lyapunov–Krasovskii functionals, a novel adaptive/robust neural tracking control scheme is developed for the first time such that all the states and signals of the closed-loop time-delay robot system are bounded and the tracking error is shown to be uniformly ultimately bounded. By suitably designing the embedded current signal, the effect of time-delay uncertainty in the mechanical dynamics does not require to be incorporated into the current tracking error dynamics, and so the Lyapunov–Krasovskii functionals can be easily constructed in the stability analysis. Compared with the previous investigations of controlling robots the control scheme developed here can be extended to handle a broader class of electrically driven robots perturbed simultaneously by plant uncertainties, time-varying perturbations, and time-delay uncertainties. Finally, simulation examples are made to demonstrate the effectiveness of the proposed control algorithm.     

不确定时滞系统的输出反馈稳定化控制器设计

研究了一类具有时变参数不确定性的时滞系统输出反馈鲁棒镇定问题.证明了这 样的问题可以转化成不带任何不确定性的线性时不变系统的H∞控制问题.从而应用现有 H∞控制问题的求解方法得到不确定时滞系统的稳定化输出动态反馈控制器设计方法.