多通道约束下的网络控制系统的最优跟踪性能

本文针对双通道约束下的线性时不变网络控制系统的随机信号跟踪性能极限问题进行了研究.网络通信包含通信噪声和通信带宽两种信道因素.被控系统考虑是非最小相位和不稳定系统,并且系统包含多个不同的非最小相位零点和多个不同的不稳定极点.对上行通道和下行通道都存在通信带宽约束及高斯白噪声影响的情形,从频域角度,通过采用双自由度控制器和尤拉参数化方法,获得了此类网络控制系统的最优可达的跟踪性能.研究结果表明网络控制系统的跟踪性能极限完全由被控对象的结构特征(非最小相位零点、不稳定极点以及被控对象的系统增益),参考输入信号和网络特性(高斯白噪声的统计特征、通信信道带宽)所决定.最后,仿真结果检证了所得结果的正确性.     

基于丢包和带宽限制网络化系统稳定性分析

基于数据包丢失和网络带宽限制研究了网络化系统稳定性问题.通信网络的特征通过数据包丢失、带宽和加性白噪声来体现.采用频域的方法得到了网络化系统稳定所需信噪比的最小(极限)值.该最小(极限)值说明了网络化系统稳定所需信噪比是由通信网络通道的丢包率、带宽、系统的不稳定极点的位置和非最小相位零点的位置决定.研究结果进一步揭示网络化系统稳定所需信噪比的最小(极限)值与系统本质特征(非最小相位零点的位置和不稳定极点的位置)和通信网络参数(数据包丢失和带宽)的关系.仿真结果说明该理论的正确性.     

多变量离散系统随机信号跟踪性能极限

研究线性时不变、多变量、离散系统对随机信号的跟踪性能极限问题, 所考虑的随机参考输入信号为布朗运动序列. 研究结果表明此类系统的跟 踪性能极限完全由被控对象的结构特征和参考输入的统计特征决定, 其中, 结构特征指被控对象的非最小相位零点和不稳定极点的位置和方向. 作为特殊情形, 本文给出了参考输入为一致随机信号以及被控对象仅含有单个非最小相位零点和单个不稳定极点时系统跟踪性能极限问题的解. 最后, 给出了两自由度补偿器跟踪系统对随机信号的跟踪性能极限.     

编解码和时延约束下的网络化控制系统最优跟踪性能

本文研究了具有丢包、时延、编解码等通信资源受限下多输入多输出离散时间网络控制系统的最优跟踪性能. 基于频域方法, 采用二元随机过程来模拟数据包丢失, 并假设信道噪声是加性高斯白噪声(AWGN), 推导了在丢包、信道噪声、时延和编解码影响下的跟踪性能极限. 采用单参数补偿器(SDOF), 利用互质分解、Youla参数化等工具得到了编解码和时延约束下的网络控制系统最优跟踪性能的显式表达式. 结果表明, 跟踪性能与对象的固有特性(非最小相位零点与不稳定极点的位置和方向)、时延、丢包率和AWGN 功率谱密度密切相关.     

系统性能极限理论的回顾和展望

描述了系统性能极限理论的研究对象、背景和意义,并简要介绍了系统性能极限理论所涉及到的四个相关问题,如:左可逆与右可逆系统、零点与零点方向、极点与极点方向以及灵敏度函数与互补灵敏度函数.同时,从H2型性能极限、频域及H∞型性能极限、时域及其他性能极限三方面综述了系统性能极限理论的研究现状,并对其未来的发展进行了展望.     

网络化系统周期信号的跟踪

研究线性时不变、单变量、离散网络化系统对周期信号的跟踪问题.与现有文献考虑的参考输入信号大都为常见的能量信号所不同的是,本文参考输入信号是离散时间周期方波功率信号.相应地,研究系统对基于功率谱的参考输入信号功率的响应,系统的跟踪性能通过输入信号与受控对象输出之差的功率来衡量,而最优跟踪性能采用跟踪误差的平均功率来度量.考虑的网络化控制系统仅上行通道存在丢包误差的影响,把丢包过程看作两个信号的合成,一是确定性信号,二是随机过程,进而丢包误差描述为源信号和白噪声之间乘积.根据被控对象和随机过程的性质,采用Parseval等式、维纳–辛钦定理和范数矩阵理论得到该系统跟踪性能极限的下界表达式.仿真结果表明,所设计的控制器能实现对周期信号的有效跟踪,进而验证了结论的正确性.     

跟踪微分器用于零点配置

1　引言在线性系统理论中 ,只要系统可控 ,通过线性状态反馈可以任意配置系统极点来改善系统的动态性能 .能否通过配置系统的零点来改善系统的动态性能 ,特别是系统的传递特性 ,由于零点配置需用微分环节 ,而传统的“微分器”对噪声敏感 ,很难用于零点配置上 .本文将用信噪比很高的新型“非线性跟踪微分器 (TD)”[1 ] 来提取微分信号 ,从而能够用零点配置的方法来改善系统的动态性能 .数值仿真例子表明本文提出的方法很有效 .2　跟踪微分器用于零点配置如果二阶系统 x-f(x,x) =u是稳定的线性系统 ,即 f(x,x) =-a1 x-a2 x,a1 >0 ,a2…     

极点配置固定滞后稳态Kalman平滑器

基于稳态Kakman预报器和白噪声估计理论, 应用控制理论中的极点配置原理, 提出了极点配置固定滞后稳态Kalman平滑器. 它们不仅是全局渐近稳定的, 而且通过配置平滑器的极点可使初始平滑估值的影响按指数衰减迅速消失. 它们避免了计算最优初始平滑估值, 可减小计算负担. 一个雷达跟踪系统的仿真例子说明了其有效性     

细胞神经网络超混沌同步系统性能分析及应用

构造状态观测器可实现混沌同步.常规的研究方法是通过任意配置极点来达到同步,但对同步系统的性能分析较少.设计了一个新的五维细胞神经网络超混沌同步系统,研究分析表明极点配置与同步速度密切相关.为最大限度地减少噪声对收发双方同步误差的干扰,提出了选择反馈矩阵和补差值相结合的方法,并将其应用于多通道图像保密通信系统,仿真结果表明该设计方法可实际应用于多媒体保密通信之中.     

基于动态观测器零极点优化的网络控制系统故障检测

针对网络化控制系统中在有限频扰动和噪声下的传感器故障检测问题,构建一种新型的观测器结构:动态观测器.利用动态观测器零点可配置这一新特性,提出零点和极点联合优化配置的故障检测方法.所提出的动态观测器是在传统比例积分观测器的基础上扩展而成,更具一般性,具有零点可配置的特点,能够克服传统观测器零点是固定的限制.将动态观测器的零点配置到有限频率测量扰动信号和网络传输延时等外部扰动的特征频谱处,利用零点的特性更好地衰减扰动对残差的影响.给出观测器故障检测的综合性能指标,结合$H_2/H_\infty$优化方法优化动态观测器极点.最后以网络化两轮自平衡机器人的模型为例,比较动态观测器、比例积分观测器、比例观测器的故障检测效果.仿真结果验证了所提动态观测器故障检测方法的优势和有效性.     

Optimal tracking performance of MIMO control systems with communication constraints and a code scheme

This paper investigates the issue of the optimal tracking performance for multiple-input multiple-output linear time-invariant continuous-time systems with power constrained. An H₂ criterion of the error signal and the signal of the input channel are used as a measure for the tracking performance. A code scheme is introduced as a means of integrating controller and channel design to obtain the optimal tracking performance. It is shown that the optimal tracking performance index consists of two parts, one depends on the non-minimum phase zeros and zero direction of the given plant, as well as the reference input signal, while the other depends on the unstable poles and pole direction of the given plant, as well as on the bandwidth and additive white noise of a communication channel. It is also shown that when the communication does not exist, the optimal tracking performance reduces to the existing normal tracking performance of the control system. The results show how the optimal tracking performance is limited by the bandwidth and additive white noise of the communication channel. A typical example is given to illustrate the theoretical results.     

基于量化控制信号的线性系统的跟踪性能极限

研究基于量化控制信号的线性系统的跟踪性能极限. 所研究的被控对象是稳定的线性时不变(LTI)系统, 参考跟踪信号是阶跃信号. 跟踪性能通过对象输出与参考信号之差的能量来衡量. 为了达到渐近跟踪, 提出了一个新的量化方案. 方案包括两部分: 一部分是在初始时刻将控制信号的稳态值通过网络传输给被控对象并且存储在其输入端; 另一部分则是通过对数量化器, 对控制信号的瞬态部分(即控制信号与其稳态值之差)进行量化, 然后传输给被控对象. 最后该量化信号与稳态控制信号相加后作用于被控对象. 这里, 假设对数量化误差是     

Regulation performance limitation of networked time-delay systems with incomplete information

In this paper, the regulation performance limitation of networked time-delay systems is studied. The communication network is mainly affected by parameters such as packet dropouts, encoding-decoding, interference signal, and channel noises. Non-minimum phase zeros, unstable poles, and time delay are all considered for a given plant. The corresponding regulation performance expression is derived using coprime factorization and spectral decomposition techniques in the frequency domain. The results indicate that the regulation performance of the system is related to the inherent characteristics of the given plant, including non-minimum phase zeros, unstable poles, and time delay. Additionally, network communication parameters such as white Gaussian noise, packet dropouts, encoding-decoding, and external interference signals all affect the regulation performance of networked time-delay systems. Finally, some simulation examples are provided to demonstrate the effectiveness of the theory.     

Optimal tracking performance of MIMO discrete‐time systems with communication constraints

The optimal tracking problem for multiple‐input multiple‐output linear‐time‐invariant discrete‐time systems with communication constraints in the feedback path is studied in this paper. The tracking performance is measured by the energy of the error signal between the output of the plant and the reference signal. The objective is to obtain an optimal tracking performance, attainable by all possible stabilizing compensators. It is shown that the optimal tracking performance consists of two parts, one depends on the nonminimum phase zeros and zero direction of the given plant, as well as the reference input signal direction, and the other depends on the nonminimum phase zeros, unstable poles, and pole direction of the given plant, as well as the bandwidth and additive white Gaussian noise of the communication channel. It is also shown that, if the constraint of the communication channel does not exist, the optimal tracking performance reduces to the existing tracking performance of the control system without communication constraints. A typical example is given to illustrate the theoretical results. Copyright © 2011 John Wiley & Sons, Ltd.     

Best Tracking Performance of Networked Control Systems Based on Communication Constraints

The best tracking problem for a single‐input‐single‐output (SISO) networked control system with communication constraints is studied in this paper. The tracking performance is measured by the energy of the error signal between the output of the plant and the reference signal. The communication constraints under consideration are finite bandwidth and networked induced‐delay. Explicit expressions of the minimal tracking error have been obtained for networked control systems with or without communication constraints. It is shown that the best tracking performance dependents on the nonminimum phase zeros, and unstable poles of the given plant, as well as the bandwidth and networked induced‐delay. It is also shown that, if the constraints of the communication channel do not exist, the best tracking performance reduces to the existing tracking performance of the control system without communication constraints. The result shows how the bandwidth and networked induced‐delay of a communication channel may fundamentally constrain a control system's tracking capability. Some typical examples are given to illustrate the theoretical results.     

Modified performance of MIMO wireless networked time‐delay systems over fading channels

In this paper, the modified performance limitation of multi‐input multi‐output (MIMO) wireless networked time‐delay systems over fading channels is investigated, where the characteristic of the fading channels is assumed to be a random process. The modified tracking performance limitation is considered based on frequency domain representation. The display expressions of performance limitation are achieved by using the co‐prime factorization and the spectral decomposition techniques. The obtained results show that the modified performance limitation of the wireless networked time‐delay systems is related to the inherent characteristics of the given plant, including the non‐minimum phase zeroes, the unstable poles, the encoding‐decoding, the fading channels, the bandwidth and the modified factor. Finally, some numerical examples are provided to demonstrate the efficiency of the proposed design method.     

Performance Limitation of Networked Systems with Network‐Induced Delay and Packet‐Dropout Constraints

In this paper, we deeply investigate the tracking performance limitation of single‐input single‐output (SISO) networked systems with packet dropouts and network‐induced delay constrains, where the power of the tracking error is adopted to measure of the performance and is minimized by searching through all stabilizing one‐parameter controllers, with/without considering the channel input power. Moreover, the explicit expressions of the tracking performance limitation are obtained by applying the spectral factorization technique. Theoretical analysis shows that the tracking performance limitation is closely dependent on non‐minimum phase zeros, unstable poles of a given plant, the characteristics of the reference signals, network‐induced delay and packet dropouts probability of communication channel. Finally, some typical examples and simulations are conducted to illustrate the theoretical results.     

Performance limitations for networked control systems with plant uncertainty

There has recently been significant interest in performance study for networked control systems with communication constraints. But the existing work mainly assumes that the plant has an exact model. The goal of this paper is to investigate the optimal tracking performance for networked control system in the presence of plant uncertainty. The plant under consideration is assumed to be non-minimum phase and unstable, while the two-parameter controller is employed and the integral square criterion is adopted to measure the tracking error. And we formulate the uncertainty by utilising stochastic embedding. The explicit expression of the tracking performance has been obtained. The results show that the network communication noise and the model uncertainty, as well as the unstable poles and non-minimum phase zeros, can worsen the tracking performance.