网络化控制系统的科学问题与应用展望

作为在串行网络上实现反馈控制回路的控制系统，网络化控制系统减少了系统布线，增加了系统的柔性，提高了系统的可诊断性和可维护性．在综述网络化控制系统研究现状与进展的基础上，对网络化控制系统所涉及的科学问题和应用领域进行了深入分析，并对网络化控制系统的未来发展作了展望．     

多回路网络化控制系统级联反馈调度

针对动态环境下的多回路网络化控制系统，本文基于反馈控制与网络调度协同设计的思想，提出一种级联反馈调度策略．以优化系统整体控制性能为目标，根据可用带宽资源的动态变化，对控制回路采样周期进行在线调节，将截止期错过率控制在期望的较低水平，并对可用带宽进行优化分配．仿真实验结果表明，相对于传统设计方法，该方法能够明显改善整体控制性能．     

网络化控制系统中的延时问题:分析与展望

网络诱导延时是引起网络化控制系统性能下降甚至不稳定的主要因素之一,如何减小延时或降低其不确定性以克服延时的不利影响,一直是网络化控制系统研究领域的一个关键问题.对此,从控制和通讯网络两方面出发,对目前关于延时问题的研究结果进行了详细的论述和总结;通过系统地分析和对比,指出现有理论成果中存在的问题和不足;最后,指出该领域今后的主要任务和发展方向,并给出了一些有益的建议.

     

网络化控制系统的研究现状与展望

随着网络技术的发展,网络化控制系统日益成为人们关注的课题,特别是目前工业以太网所取得的进展引起人们广泛兴趣。介绍了网络化控制系统的发展过程,在综述网络化控制系统研究现状的基础上,对网络化控制系统的建模、状态估计、信息时延、调度算法、通信约束等方面进行了深入分析,并对其中的建模、网络信息调度的最优化、网络环境下控制理论研究、应用研究等方面的未来发展作了展望。     

基于调度的网络化控制系统

网络化控制系统NCSs(NetworkedControlSystems)是基于网络的分布式控制系统,具有强实时性。本文分析了网络控制系统的特点,网络时延与控制系统性能间的关系,分类介绍了当前网络化控制系统的研究方法、分析角度及策略。     

网络化控制系统改进事件触发机制与L∞控制协同设计研究

文章研究了网络诱导延时和外部干扰约束下,网络化控制系统的改进事件触发机制与 控制协同设计策略。为了克服相对(绝对)事件触发机制在系统接近(远离)平衡点运行时数据发送率较高的局限,文章提出了综合利用状态相关信息和状态无关信息的改进事件触发机制,其能够在系统整体运行期间获得较低数据发送率。然后,建立了同时刻画事件触发机制和网络诱导延时影响的闭环时滞系统模型,得到了系统最终有界稳定的充分条件,给出了事件触发机制与控制器的协同设计方法,比要求控制器预先给定的两步设计方法更方便。最后,仿真验证了所提方法的有效性。     

基于单片机与延时芯片的延时控制系统

目前对时间把握的高精度控制在信号检测与控制、人工智能、电子技术等学科领域里得到了广泛的应用.本文以新型可编程线延时芯片DS1020和单片机为基础,设计可编程延时控制系统,以达到对时间进行精密时延控制的需求.同时基于系统任务要求,采用了计算机技术、电子技术和通讯技术研制了系统的软硬件.其中下位单片机软件采用MCS-51汇编程序编写;工业控制计算机监控软件以Window:操作系统为平台,用Delphi语言实现与下位单片机之间的串口通信.     

网络控制系统中的调度问题

网络控制系统（NCS）的控制性能受限于共享的计算资源和网络资源,如何对NCS中的周期和非周期的复杂信息流进行有效的调度成为影响系统控制性能的关键因素。从实时控制角度,分析了NCS中的时态特性和NCS的实时调度问题。同时从实时CPU调度策略、NCS网络调度方法、调度诱导问题及其补偿方法、可调度性分析和调度优化、控制与调度协同设计等方面综述了现有的NCS中的调度理论和方法,并讨论了今后进一步的研究方向。     

网络控制系统延时稳定性的分析与仿真

本文介绍了网络控制系统延时模型的建立,论述了如何对延时模型的稳定性进行分析,并在MATLAB环境下进行了仿真。     

网络化控制系统性能与网络QoS协调设计研究*

基于网络QoS如延迟、丢包,建立网络化控制系统状态方程,通过双线性矩阵不等式(BMI)讨论在某种网络QoS下控制系统的稳定性,并以离散系统二次型性能指标为例设计最优LQR(linear quadratic regulator)控制器,得到保证系统控制性能的网络QoS约束。针对该约束,提出一种能够兼顾系统性能与网络QoS的网络化控制系统控制与调度协调设计方法。最后,通过仿真实验说明提出的协调设计方法的必要性和有效性。     

Co-simulation platforms for co-design of networked control systems: An overview

This paper gives an overview of the existing co-simulation platforms for co-design of networked control systems (NCSs). NCSs contain coupled control and communication perspectives. However, the existing simulators focus either on control systems or communication networks. In order to analyse the coupling effect from both sides, co-simulation method is under consideration as one of the most promising solutions. This paper briefly introduces the commonly used individual control and communication simulators. Then the existing co-simulation platforms have been reviewed and discussed. Synchronization technique is the key point toward co-simulation, thus different synchronization methods have also been summarized. Two sample case studies with results are provided to show the beneficial of co-simulations.     

资源受限的网络控制系统调度

结合具有多控制回路的网络控制系统框架结构,设计了反馈调度器以实现调度策略.根据控制性能最优化要求,分析了系统的可调度性.通过实时调整各控制回路的采样周期,采用优先级分配方法,在线优化多控制回路的网络控制系统性能.通过对3个控制回路组成的网络控制系统进行仿真实验,验证了可调度分析和调度策略的有效性.     

Modelling and control of networked control systems with both network-induced delay and packet-dropout

A new switched linear system model is proposed to describe the networked control system (NCS) with both network-induced delay and packet-dropout. A sufficient condition is derived for the exponential stability of the closed-loop NCS, and the obtained condition establishes the quantitative relation between the packet-dropout rate and the stability of the NCS. Design procedures for the state feedback stabilising controllers are also presented by using the augmenting technique. An illustrative example is provided to demonstrate the effectiveness of the proposed method.     

Error encoding algorithms for networked control systems

A networked control system is characterized by having a feedback loop closed through a local area network. This paper considers methods for scheduling the use of the network to guarantee both stability and controller performance. We propose and validate algorithms for choosing message identifiers for dynamically scheduled networked control systems. Two schemes for selecting priority levels are proposed: a fixed arbitrary grid and an auto-scaling grid. We prove that the system is uniformly ultimately bounded in the case of the fixed encoding scheme, and asymptotically stable with auto-scaling. An inverted pendulum is used to illustrate the encoding methods.     

可重构技术及其在网络控制系统中的应用综述

可重构技术在对系统的维护、优化、扩展以及自适应、自组织、自恢复上有其独特的优势．对此,介绍了可重构技术的基本原理、实现方法和应用领域;阐述了其在网络控制系统中分别对系统、节点和协议的应用．并对其发展趋势进行了展望．     

Analysis and synthesis of networked control systems: Topological entropy, observability, robustness and optimal control

This paper extends the concept of topological to the case of uncertain dynamical systems. We address problems of observability and optimal control via limited capacity digital communication channels. The main results are given in terms of inequalities between date rate of the communication channel and topological entropy of the open-loop system. Topological entropy is calculated for some classes of uncertain dynamical systems.     

Input-to-state stability of networked control systems

A new class of Lyapunov uniformly globally asymptotically stable (UGAS) protocols in networked control systems (NCS) is considered. It is shown that if the controller is designed without taking into account the network so that it yields input-to-state stability (ISS) with respect to external disturbances (not necessarily with respect to the error that will come from the network implementation), then the same controller will achieve semi-global practical ISS for the NCS when implemented via the network with a Lyapunov UGAS protocol. Moreover, the ISS gain is preserved. The adjustable parameter with respect to which semi-global practical ISS is achieved is the maximal allowable transfer interval (MATI) between transmission times.     

Stochastic optimal control of networked control systems with control packet dropouts

This paper considers the stochastic optimal control problem for networked control systems(NCSs)with control packet dropouts.The proportional plus up to the third-order derivative(PD3)compensation strategy is adopted to compensate for control packet dropouts at the actuator by using the past control packets stored in the buffer.Based on the strategy,a new NCS structure model with packet dropouts is provided,where the packet dropout is assumed to obey the Bernoulli random binary distribution.In terms of the given model,the stochastic optimal control law is proposed. Numerical examples illustrate the effectiveness of the results.     

On the model-based approach to nonlinear networked control systems

The problem of model-based stabilization of a nonlinear system based on its approximate discrete-time model is addressed, under the assumption that both the feedforward and the feedback paths are subject to network-induced constraints. These constraints include irregularity of the transfer intervals, time-varying communication delays, and the possibility of packet losses. A communication protocol that copes with these constraints is proposed. A “Stability+performance recovery” result for the nonlinear model-based networked control system (NCS) is formulated and proven.Simulation results presented confirm that the proposed method improves the maximum allowable transfer interval.     

Event-triggered controller design of nonlinear discrete-time networked control systems in T-S fuzzy model

This article is concerned with event-triggered fuzzy control design for a class of discrete-time nonlinear networked control systems (NCSs) with time-varying communication delays. Firstly, a more general mixed event-triggering scheme (ETS) is proposed. Secondly, considering the effects of the ETS and communication delays, based on the T-S fuzzy model scheme and time delay system approach, the original nonlinear NCSs is reformulated as a new event-triggered networked T-S fuzzy systems with interval time-varying delays. Sufficient conditions for uniform ultimately bound (UUB) stability are established in terms of linear matrix inequalities (LMIs). In particular, the quantitative relation between the boundness of the stability region and the triggering parameters are studied in detail. Thirdly, a relative ETS is also provided, which can be seen as a special case of the above proposed mixed ETS. As a difference from the preceding results, sufficient conditions on the existence of desired fuzzy controller are derived to ensure the asymptotic stability of the closed-loop system with reduced communication frequency between sensors and controllers. Moreover, a co-design algorithm for simultaneously determining the gain matrices of the fuzzy controller and the triggering parameters is developed. Finally, two illustrative examples are presented to demonstrate the advantage of the proposed ETS and the effectiveness of the controller design method.