基于网络服务质量的网络控制器设计

针对网络服务质量对控制系统性能的影响, 建立了联合网络参数和控制器参数的系统模型. 在此基础上分析了网络控制系统保性能控制器存在的网络参数和控制参数依赖条件, 并且通过求解线性矩阵不等式, 给出了控制器的参数化设计方法. 所设计的控制器在满足一定的网络服务质量摄动范围内, 不仅可以使系统渐近稳定,而且还能确保系统性能不大于上界. 本文方法给出网络服务质量变化对控制系统性能衰减的一种定量度量, 可以为进一步的网络调度提供理论依据.     

基于自适应模糊神经网络控制器的网络控制系统

网络控制系统中存在着时延、丢包、网络干扰等问题。针对网络控制系统中存在恶化系统的控制性能,甚至导致系统不稳定的因素,提出了一种基于自适应模糊神经网络控制器的网络控制系统,它能根据系统的实际输出与期望输出误差,利用自适应模糊控制和神经网络自学习的原理进行控制参数的自行调整,以符合控制系统的实际要求,同时,分析了网络延时,丢包率及网络干扰因素对系统性能的影响。利用TrueTime工具箱建立了包含自适应模糊神经网络控制器的网络控制系统的仿真模型,并将其分别与基于常规PID控制器的网络控制系统和基于模糊参数PID控制器的网络控制系统进行了比较。实验结果表明,在相同的网络环境下,基于自适应模糊神经网络控制器的网络控制系统的控制效果比基于常规的PID控制器和基于模糊参数PID控制器的要好,且具有较好的抗干扰能力和鲁棒性能。     

LQG算法在双容水箱网络控制系统中的应用研究

针对网络控制系统中由于随机延时而导致系统不稳定的问题,描述了网络化预测控制系统的设计和实现.首先用机理法建立了双容水箱的数学模型,然后通过LQG算法调整到较好的控制参数,最后设计网络预测控制器和网络延时补偿器来补偿随机延时,使系统控制性能得到了较大的提高,取得了较好的仿真效果.     

具有传感器故障的网络控制系统保性能可靠控制

基于存在时延和丢包的网络传输环境.针对具有参数不确定性的网络化控制系统,研究了其在传感器故障条件下的保性能可靠控制问题.根据Lyapunov稳定性理论和线性矩阵不等式(LMIs)方法,推导出使闭环网络控制系统在传感器故障条件下渐近稳定且保证综合性能指标满足要求的充分条件,并利用LMIs提出了保性能可靠控制率的设计方法.该控制算法在提高网络化控制系统可靠性的同时有利于系统综合体性能的优化.数值仿真验证了该方法的可行性和有效性.     

网络控制系统的时延相关状态反馈控制器设计

研究了具有时延、丢包和数据包时序错乱的网络控制系统镇定问题.为了有效提高系统的控制性能,本文根据网络控制系统的特点提出一种时延相关状态反馈控制方法,并将闭环网络控制系统建模为离散时间切换模型.在此基础上,通过构造依赖于参数的Lyapunov函数给出了闭环网络控制系统的稳定条件和镇定控制器设计方法.仿真结果和实验结果表明所提方法的有效性和可用性.     

禁忌遗传算法整定的网络拥塞控制研究

研究网络拥塞优化控制问题,网络路由器是网络拥塞的主要控制单元,当网络业务流量大增,造成路由器缓存队列增加,引起时延抖动.传统网络路由器采用PID控制方式,与控制效果相关的3个参数,采用试验和试凑等人工方式进行优化,参数一旦确定就固定不变,而网络上信息流量具有时变性和突发性,因此传统PID固定参数方式不能适合网络变化特点,导致网络容易产生拥塞现象.为了更好防止网络拥塞,提出一种禁忌遗传算法的网络拥塞控制方法.用遗传算法的全局搜索方式对网络路由器PID控制参数进行寻优,再用禁忌搜索算法对遗传算法得到的PID参数进行局部求精搜索,最后获得最优网各路由器PID控制参数.仿真结果表明,禁忌遗传算法能够很好的适应网络流量变化规律,更快找到最优路由器PID控制参数,提高控制效果,有效控制网络流量,减少了网络传输时延,为优化控制提供了参考.     

移动自组网性能评价参数的研究及仿真分析

在移动自组网中,路由协议是影响网络性能的关键因素,因而对协议性能评价指标的研究非常重要.目前,对协议性能的评价主要是通过网络仿真平台来进行,在网络仿真中衡量一个协议优劣的重要标准是网络性能评价参数.文中根据移动自组网络的固有特性详细分析了网络性能评价参数,给出了各参数的计算方法.介绍了GloMoSim仿真器,并分析了Glo-MoSim仿真器的结构;给出了各参数在GloMoSim仿真环境下的计算和评价方法,并对DSR、AODV和WRP三个协议进行了仿真与结果分析.     

基于IEEE 802.15.4的无线传感器网络性能分析*

通过将IEEE 802.15.4标准中的超帧与无线传感器网络的LEACH协议结合,在星型网络拓扑下,网络节点通过申请超帧中的GTS来进行无冲突的数据通信,对使用GTS传输数据的这一过程进行了研究,从理论上分析了无线传感器网络的网络性能.仿真结果说明了网络控制参数对网络性能的影响,为今后无线传感器网络应用中的参数配置提供了一定的理论基础.     

具有传感器故障的网络控制系统保性能可靠控制

基于存在时延和丢包的网络传输环境,针对具有参数不确定性的网络化控制系统,研究了其在传感器故障条件下的保性能可靠控制问题.根据Lyapunov稳定性理论和线性矩阵不等式(LMI)方法,推导出使闭环网络控制系统在传感器故障条件下渐近稳定且保证综合性能指标满足要求的充分条件,并利用LMIs提出了保性能可靠控制率的设计方法.该控制算法在提高网络化控制系统可靠性的同时有利于系统综合体性能的优化.数值仿真验证了该方法的可行性和有效性.

     

基于truetime的网络控制系统时延分析与仿真

在分析了网络控制系统结构,研究了产生传输时延的原因并分析了网络控制系统传输时延的具体组成.利用了基于MATLAB/Simulink的truetime网络控制系统仿真工具,构建了一个以直流电机为控制对象的网络控制系统时延仿真模型,讨论了在无传输时延与有传输时延下,网络时延对控制系统性能的影响.     

具有通信约束的网络化控制系统容错控制研究

Implementing a control system over a communication network induces inevitable time delays that may degrade performance and even cause instability. One of the most effective ways to reduce the negative effect of delays on the performance of networked control system (NCS) is to reduce network traffic. In this paper, adjustable deadbands are explored as a solution to reduce network traffic in NCS. A method of fault-tolerant control of networked control system is presented, which takes into account system response as well as network traffic. The integrity design for a kind of NCS with sensor failures and actuator failures is analyzed based on robust fault-tolerant control theory and information scheduling. After detailed theoretical analysis, the paper also provides the simulation results, which further validate the proposed scheme.     

时隙ALOHA协议下的网络化控制系统协同设计

针对网络化控制系统中信道容量有限的问题,本文提出一种基于时隙ALOHA通信协议的控制与通信协同设计方法.将控制系统的采样周期划分为若干等长度的时隙,在每个时隙中,系统的分布式传感器通过时隙ALOHA协议来随机竞争接入网络.由于在不同的采样周期各个传感器的接入状态不同,整个状态反馈控制系统将在若干子系统之间进行切换.据此,本文建立了离散的切换系统模型,并利用分段李雅普诺夫函数方法和平均驻留时间技术得到了能够保证系统指数稳定的充分条件.然后,给出能够保证控制系统稳定所需的信道吞吐率的界限,进而得到了时隙ALOHA协议中的最大重传次数与控制系统衰减率的定量关系.通过上述方法,本文建立了控制-通信协同设计的框架结构,可将控制器的增益矩阵和时隙ALOHA通信协议进行协同设计.最后,通过仿真验证了本文所提出的协同设计方法的有效性.     

MPC-based Co-design of Control and Routing for Wireless Sensor and Actuator Networks

A wireless sensor and actuator network (WSAN) is a class of networked control systems. In WSANs, sensors and actuators are located in a distributed way, and communicate to controllers through a wireless communication network such as a multi-hop network. In this paper, we propose a model predictive control (MPC) method for co-design of control and routing of WSANs. MPC is an optimal control strategy based on numerical optimization. The control input is calculated by solving the finite-time optimal control problem at each discrete time. In the proposed method, a WSAN is modeled by a switched linear system. In the finite-time optimal control problem, a control input and a mode corresponding to a communication path are optimized simultaneously. The proposed method is demonstrated by a numerical example.     

网络控制系统的模型依赖平均驻留时间调度与控制

针对具有随机短时延的资源受限网络控制系统,提出了一种新的模型依赖平均驻留时间的调度策略与反馈控制联合设计方法.该调度策略由模型依赖平均驻留时间和动态试一次就丢弃(try-once-discard,TOD)调度策略共同决定,将系统建模成带有参数不确定性的离散切换系统,基于多Lyapunov函数方法及线性矩阵不等式(linear matrix inequality,LMI)技术,给出了使闭环系统指数稳定的控制器设计和TOD调度策略下的各模态平均驻留时间条件.该联合设计方法降低了保守性,在一定程度上减少了系统模态之间的切换频率.最后通过仿真验证所提方法的有效性.     

Hybrid Scheduling and Quantized Output Feedback Control for Networked Control Systems

A novel co-design scheme of hybrid scheduling strategy, adaptive logarithmic quantizer and dynamic robust H-infinity output feedback controller for a class of networked control system (NCS)with communication constraints and time delay is proposed. The hybrid scheduling scheme integrates dead zone scheduling and Try Once Discard (TOD) scheduling so as to get the stronger adaptability and flexibility than the single scheduling. In this scheme, dead zone scheduling which updates the threshold according to mode-dependent control strategy is used for single node of NCS to reduce the network bandwidth utilization while TOD scheduling is used for the whole node of NCS in order to meet the requirements of communication constraints and guarantee the overall system performance.We develop the integrated design for the hybrid scheduling strategy, adaptive quantizer and dynamic robust output feedback controller to maintain asymptotic stability of the closed-loop NCS by using the multiple-Lyapunov function and switched system theory. The proposed method can improve the the quality of service (QoS) meanwhile ensure the quality of control (QoC) of overall systems, which make a better trade-off between network utilization and control performance. An simulation example demonstrates the efficiency of the proposed method.     

Dual scheduling and quantised control for networked control systems with communication constraints

A novel integrated design scheme of average dwell time scheduling strategy, dynamic bandwidth allocation policy and quantised control for a collection of networked control systems (NCSs) with time delay and communication constraints is proposed in this paper. A scheduling policy is presented to accommodate the limitation of communication capacity which depends on the convergence rate of closed-loop system and divergence rate of open-loop plant. Linear programming technique is adopted to dynamically allocate bit rate for each node and the strategy is used to make trade-offs between the network utilisation and the control performance which provides an effective way of optimising the quality of control (QoC) and the quality of service (QoS) for NCSs. Mid-tread uniform quantisers update the quantisation rules according to the assignment of the bit rate and convert the quantised state into a kind of input saturation with bounded disturbances. Taking into account the effect of dual scheduling strategy and quantisation, the NCSs are modelled as discrete-time switched systems with bounded disturbances. Furthermore, a scheduling and quantised feedback control co-design procedure is proposed for the simultaneous stabilisation of the collection of networked subsystems. Finally, a simulation example is given to illustrate the effectiveness of the proposed method.     

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。     

Wireless control system design and co-simulation

This paper discusses the communication and control co-design and co-simulation of wireless networked control systems. The interactions between the network and the control system are considered, and general networking and control co-design solutions are proposed for wireless control applications. The PiccSIM simulator for wireless control system simulation is used to study the effects of specific network protocol and control algorithms in practice. Packet loss models based on measurements of real industrial radio environments are incorporated into the simulator. This allows the realistic evaluation of the suitability of the network protocols for wireless control applications. A network quality of service measure is introduced, which gives a direct relationship between the network and control performances. Two simulation cases show the capabilities of PiccSIM for wireless control application research and development, where the co-design issues and solutions are demonstrated in detail.     

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.