离散事件系统不透明性监督控制研究综述

离散事件系统不透明性是指外部观察者无法分辨系统的一系列行为是否为系统所发生的.而离散事件不透明性监督控制则是构建监督器控制系统行为,使系统满足不透明性的一种方法.离散事件系统不透明性与信息安全有着紧密的联系,并得到了广泛的应用.首先对离散事件系统做了简要的概述,然后介绍了不透明性监督控制算法的研究现状,最后进行了总结和展望.     

不完备离散事件系统的当前状态不透明性

本文针对不完备系统模型,研究不完备离散事件系统的当前状态不透明性.根据系统的实际输出与预测输出之间的差异,构建了一个具有学习功能的学习诊断器.这种学习诊断器不仅能够模拟系统的状态转移,而且还可以将系统缺失的状态信息通过学习得到恢复.通过引入集合覆盖理论处理由学习诊断器得出的结果,提出了一种基于学习诊断器的不完备离散事件系统当前状态不透明性的验证算法.     

基于粗糙集理论的离散事件系统不透明性的验证算法

近年来,离散事件系统的不透明性研究引起了国内外众多学者的广泛关注.本文针对离散事件系统的不透明性,提出了一种将粗糙集理论作为知识提取工具来处理离散事件系统不透明性验证的方法.先对离散事件系统的不透明性进行形式化,再利用粗糙集理论对离散事件系统以信息表及决策表的形式进行表示,得到一个关于离散事件系统不透明性的充分必要条件.在此基础上,给出一个验证离散事件系统不透明性算法.与现有方法相比,该验证算法既适用于对强不透明性的验证,又适用于对弱不透明性的验证,并且在时间复杂度上也有较明显改进.     

离散事件动态系统的分层最优监控

采用流网络的完备最小割将Ｋｕｍａｒ提出的离散事件系统最优监控理论拓展到标识语言的情形,提出了在受控系统的可达状态集中优化某种指标的分层优化思想,给出了寻找可控最优子语言的算法。     

离散事件系统规范DEVS研究

离散事件系统是一类常见的系统,如何对这类系统进行描述与建模是离散事件系统仿真研究的核心内容。离散事件系统规范DEVS是一种离散事件系统形式化描述方法,它具有层次化和模块化的特点,利用该方法可对复杂的离散事件系统进行建模、设计、分析和仿真。该文详细介绍了DEVS基本模型和耦合模型,给出了DEVS在耦合运算下的封闭性构造证明,并提出了一种具有嵌套层次结构的DEVS耦合模型实现算法,该算法对基于DEVS描述的离散事件系统的仿真实现具有一定参考价值。     

离散事件系统并发仿真环境

本文提出了并发仿真思想。并介绍了针对柔性制造系统仿真研制的离散事件系统并发仿真环境:将制造系统作为仿真对象部分,将控制、调度等管理方法作为决策部分,仿真对象部分和决策部分作为两个独立的作业并发执行,它们交互作用完成整个仿真过程。介绍了一个将上述两部分连接成一个完整仿真系统的接口(软件)。     

离散事件系统的稳定性

讨论离散事件系统（DES）的稳定性问题,给出DES稳定性,可吸收性和渐近稳定性有关结论,证明了关于DES稳定性的某些函数的存在性。     

离散事件系统的协调反馈控制

本文探讨以Ｐｅｔｒｉ网为模型的离散事件系统（ＤＥＳ）的某种禁止状态避免问题，提出了以Ｐｅｔｒｉ网Ｎ为基网，设计具有外部输入位置Ｐｅｔｒｉ网（ＰＮＩＰ），对Ｎ进行协调反馈控制的方法。由Ｎ现行状态反馈决定的ＰＮＩＰ的控制状态，既保证Ｎ避免禁止状态，又使Ｎ具有最大自由度。     

离散事件系统基于模型诊断的研究进展

近年来,针对离散事件系统的基于模型诊断方法在大型通讯网络、电网故障诊断等领域获得了成功应用,成为人工智能与控制工程领域的热门研究课题。介绍了针对离散事件系统的基于模型诊断的基本思想与建模方法,从不同的角度对使用自动机建模的各种主要诊断方法进行了评析与比较;讨论了系统可诊断性判定方法的研究进展。从系统建模、分布式在线诊断、不完备模型下的诊断以及系统实现等方面,展望了针对离散事件系统的基于模型诊断领域中有待解决的问题。     

Hierarchical control of timed discrete-event systems

An abstract hierarchical control theory is developed for a class of timed discrete-event systems (TDES) within the discrete-event control architectural framework proposed earlier by the authors. For this development, a control theory for TDES is introduced in the spirit of a prior theory of Brandin. A notion of time control structures is introduced, and on its basis a general property of hierarchical consistency is achieved by establishing control consistency — namely preservation of time control structures through the aggregation mapping in a two-level hierarchy.     

Opacity of discrete-event systems under nondeterministic observation mechanism

For some practical systems modeled by discrete-event systems (DESs), the event observation mechanism may be no longer static/fixed due to sensor faults/failures, packet loss, and/or measurement uncertainties. It is required to redefine the observations of events. Therefore, it is interesting to reconsider the opacity in the context of abnormal conditions as mentioned. In this paper, we extend notions of initial-state opacity (ISO), current-state opacity (CSO), and initial-and-final-state opacity (IFSO) in a standard setting to an advanced framework of nondeterministic observations (i.e., the event-observation mechanism is state-dependent and nondeterministic) by taking the output-observation-equivalence instead of the natural projection-equivalence into account. To efficiently verify them, we construct three new matrix-based information structures in this advanced framework called an initial-state estimator, a current-state estimator, and an initial-and-final-state estimator using the Boolean semi-tensor product (BSTP) theory. Accordingly, the matrix-based criteria for verifying these three types of opacity are given, respectively. Computational complexity analysis as well as illustrative examples are also provided for the proposed results.     

Modular Control and Coordination of Discrete-Event Systems

In the supervisory control of discrete-event systems based on controllable languages, a standard way to handle state explosion in large systems is by modular supervision: either horizontal (decentralized) or vertical (hierarchical). However, unless all the relevant languages are prefix-closed, a well-known potential hazard with modularity is that of conflict. In decentralized control, modular supervisors that are individually nonblocking for the plant may nevertheless produce blocking, or even deadlock, when operating on-line concurrently. Similarly, a high-level hierarchical supervisor that predicts nonblocking at its aggregated level of abstraction may inadvertently admit blocking in a low-level implementation. In two previous papers, the authors showed that nonblocking hierarchical control can be guaranteed provided high-level aggregation is sufficiently fine; the appropriate conditions were formalized in terms of control structures and observers. In this paper we apply the same technique to decentralized control, when specifications are imposed on local models of the global process; in this way we remove the restriction in some earlier work that the plant and specification (marked) languages be prefix-closed. We then solve a more general problem of coordination: namely how to determine a high level coordinator that forestalls conflict in a decentralized architecture when it potentially arises, but is otherwise minimally intrusive on low-level control action. Coordination thus combines both vertical and horizontal modularity. The example of a simple production process is provided as a practical illustration. We conclude with an appraisal of the computational effort involved.     

一类非线性大系统递阶优化的神经网络方法*

本文给出了一种求解一类非线性大系统递阶优化问题的神经网络模型，克服了非线性大系统优化中的对偶间隙与不可分性问题，并且该神经网络具有全集成化的特点，易于硬件实现，其协调网络和局部优化网络同步工作，具有很高的求解效率，适宜于系统实时优化应用。     

离散时滞大系统的最优跟踪递阶控制方法

考虑具有控制时滞及输入输出之间向通道的大系统，应用线性二次型加积分（ＬＱＩ）＾１的最优状态反馈控制理论和带时增广状态向量方法，转化原大系统为满足马尔可夫性质的增广状态大系统，再作了问题分解后，整个大系统的解可由于问题层的局部控制器和上层协调器迭代计算。     

离散事件系统部分可诊断性分析

针对离散事件系统部分可诊断性问题,提出一种量化评价与分析方法。该方法以树状结构的故障模型为基础,引入可诊断度与可诊断深度指标,能够从可诊断故障覆盖程度与精确程度两个方面对系统可诊断性进行评价,其优点是评价结果量化表示,能为部分可诊断系统的进一步评价、分析与对比提供参考。此外,还讨论了故障模型对系统可诊断度与可诊断深度两个评价指标的影响,并给出了故障模型构造的一般原则。实例分析与讨论结果表明,所提出的可诊断度与可诊断深度指标能够准确反映系统在特定故障模型下的部分可诊断状态。所提出的部分可诊断性评价方法能为基于离散事件模型的复杂系统设计与评价提供依据,并能够进一步为智能、自适应和自愈系统的设计提供参考。     

Relative predictability of failure event occurrences and its opacity-based test algorithm

In this paper, the problem of relative predictability of failure event occurrences is investigated. The notion of relative predictability is proposed for logical automata and the concept of predictable rate is introduced to characterise the predictability property of a discrete-event system, which takes values in the interval [0, 1]. Intuitively, a discrete-event system being relatively predictable means that there exist some failure events which can be predicted from the observations of the system. The relationship between relative predictability and predictability introduced by Sahika Genc et al. analysed and the analysis shows that relative predictability is weaker than predictability for discrete-event systems. Furthermore, a necessary and sufficient condition for relative predictability is presented. In particular, an opacity-based algorithm is developed to test the relative predictability, which is polynomial in the number of states of the system. Also, some examples are provided to illustrate the presented results.     

关于多通道系统的动太递阶镇定

研究镇定多通道系统的一种新策略--动态递阶控制.对线性时不变确定型通道强关联系统,得到了在给定信息结构下采用动态递阶控制可任置极点(镇定)的一个充分必要条件,解决了分散循环系统采用动态递阶控制时的最小信息结构问题,并讨论了动态协同控铋器的最小阶数,最后给出了一个数值例子.