分层离散事件系统的不透明性

针对离散事件系统（DES）的不透明性问题，结合具有分层（hierarchical）结构的自动机模型，提出了分层离散事件系统的不透明性.对分层离散事件系统进行标准化，给出了分层离散事件系统不透明性和K延迟不透明性两个概念.为了对分层离散事件系统的两种不透明性进行验证，分别构造了两种相应的不透明性验证器，得到了关于不透明性和K延迟不透明性的充分必要条件，并对构造不透明性验证器的复杂度进行了分析.     

实时离散事件系统适应性监控的一个结果

1 问题的提出 在离散事件系统监控理论中,适定性是一个很重要的问题。在文献[1,2]中,所考虑的系统对应的适定监控问题不存在最优解。在这个注记里,我们将说明对含确定性状态时间的一类实时离散事件系统,其相应的适定监控问题有最优解存在。     

连续计时离散事件系统监控及其可观性

本文提出了一种带有连续时间变量的离散事件系统(称为计时离散事件系统)结构模型.通过讨论计时语言的性质,如封闭性、可控性以及可观性,研究了计时离散事件系统的监控综合问题,并基于这些性质,分别提出了计时离散事件系统在完全可观与部分可观条件下监控器存在的充要条件.     

国民经济动员仿真演练混合仿真策略研究

国民经济动员仿真演练是一个复杂的基于HLA的分布式离散事件仿真过程,包括人在回路与无人在回路的混合仿真环节,且一次演练中参演单位数量非常多,需要解决高效的实时与超实时混合仿真控制问题.在分析仿真演练特点的基础上,将并行离散事件仿真(PDES)技术应用于联邦成员仿真控制过程,提出联邦成员离散事件仿真与成员内部PDES混合仿真策略.在分析时间推进过程的基础上,设计全局仿真时间控制机制.混合仿真策略可以支持实时与超实时混合仿真模式,并能充分地提高仿真并行能力,而全局时间控制则保证了系统时间的有效推进.     

实时并发离散事件系统的监控

用受控赋时Ｐｅｔｒｉ网为具有并发事件的实时离散事件系统建模，并研究了这类模型下的监控问题，给出了实现给定并发事件语言的监控器存在的充要条件和一种动态监控方法。     

柔性制造系统实时调度的有色Petri网和状态方程模型

柔性制造系统(FMS)的实时调度问题是一个典型的并发系统(CA),亦称为离散事件动态系统(DEDS).这是一类很复杂的动态系统,本文尝试用Petri网和有色Petri网对FMS的实时调度问题建立动态模型并同时给出了代数形式的状态方程模型.     

用神经网络实现离散事件系统监控可能性研究

本文讨论了Hopfield神经网络的以描述人造系统为主的离散事件系统打似之处，以及用神经网络作为离散事件系统模型和监控器的可能性，并指出神经网络优化算法用于实时监控综合的优点及需要解决的问题。     

混合动态系统的联通格式

混合动态系统是指即具有连续动力学特性又具有离散事件驱动性质的一类特殊的动力系统,并且两者之间存在着相互耦合作用.例如在"机群作战战术与防空系统效能"仿真中,有诸如飞机及导弹飞行等的连续事件系统,有探测模型、目视模型、火力击中目标、高炮发射过程等离散事件系统.混合系统有明显的外部特征,如不连续性、自治/受控切换以及自治/受控状态跳变等.为了研究这类系统的动态特性,研究人员开发了各类仿真软件,这些软件一些实现了产生系统模型的功能,一些实现了实时仿真功能,一些实现了实时监控模型运行的功能.而在一个系统仿真过程中需要用到不同软件来完成整个仿真任务,这就要求各个软件之间能够实现数据通信.而混合动态系统的联通格式实现了软件之间的数据共享.     

事件空间离散完整系统的Noether理论

研究差分离散变分原理和事件空间中离散完整系统的Noether理论. 运用差分离散变分方法,通过群的无限小变换,得到了事件空间中离散完整系统的差分离散变分原理,并建立了离散的运动方程. 得到了系统的Noether对称性的判据方程和Noether守恒量的形式以及其存在的条件. 举例说明结果的应用.     

离散事件动态系统事件时序的鲁棒性

指出了离散事件动态系统事件时序同离散事件动态系统的若干重要性质的联系.对 于极大代数描述的DEDS模型,较系统地研究了事件时序在参数发生区间摄动情形下的鲁 棒性的有限检验问题.对于事件发生时刻是摄动参数的仿射线性函数的情形,得到事件时序 鲁棒性的Kharitonov-like判据.对于事件发生时刻是摄动参数的多项式函数的情形,证明其 通常不存在事件时序鲁棒性的顶点有限检验判据.给出了这种情形下事件时序在参数发生摄 动时能够保持的一个充分条件.     

A note on deciding controllability in pushdown systems

Consider an event alphabet /spl Sigma/. The supervisory control theory of Ramadge and Wonham asks the question, given a plant model G, with language K L/sub M/(G)/spl sube//spl Sigma//sup */ and another language K/spl sube/ L/sub M/(G), is there a supervisor /spl psi/ such that L/sub M/(/spl psi//G)=K. Ramadge and Wonham showed that a necessary condition for this to be true is the so-called controllability of K with respect to L/sub M/(G). They showed that when G is a finite state automaton and K is a regular language (also generated by a finite state automaton), then the controllability property was decidable for K. The class of languages generated by pushdown automata properly includes the regular languages. They are accepted by finite state machines coupled with pushdown stack memory. This makes them interesting candidates as supervisory languages, since the supervisor will have nonfinite memory. In this note, we show the following: i) If S is a specification given by a deterministic pushdown automaton and L is generated by a finite state machine, then there is an algorithm to decide whether K=S/spl cap/L is controllable with respect to L. ii) It is undecidable for an arbitrary specification S generated by a nondeterministic pushdown automaton and plant language L generated by a finite state machine whether K=S/spl cap/L is controllable with respect to L.     

Grid automata and supervisory control of dense real-time discrete event systems

We present a generalization of the classical supervisory control theory for discrete event systems to a setting of dense real-time systems modeled by Alur and Dill timed automata. The main problem involved is that in general the state space of a timed automaton is (uncountably) infinite. The solution is to reduce the dense time transition system to an appropriate finite discrete subautomaton, the grid automaton, which contains enough information to deal with the timed supervisory control problem (TSCP). The plant and the specifications region graphs are sampled for a granularity defined in a way that each state has an outgoing transition labeled with the same time amount. We redefine the controllability concept in the context of grid automata, and we provide necessary and sufficient solvability conditions under which the optimal solution to centralized supervisory control problems in timed discrete event systems under full observation can be obtained. The enhanced setting admits subsystem composition and the concept of forcible event. A simple example illustrates how the new method can be used to solve the TSCP.     

A Note on the Properties of the Supremal Controllable Sublanguage in Pushdown Systems

Consider an event alphabet Sigma. The supervisory control theory of Ramadge and Wonham asks the question: given a plant model G with language L_M (G) sube Sigma* and another language K sube L_M (G), is there a supervisor phi such that L_M (phi/G) = K? Ramadge and Wonham showed that a necessary condition for this to be true is the so-called controllability of K with respect to L_M (G). They showed that when G is a finite-state automaton and K is a regular language (also generated by a finite state automaton), then there is a regular supremal controllable sublanguage sup_C (K) sube K that is effectively constructable from generators of K and G. In this paper, we show: 1) there is an algorithm to compute the supremal controllable sublanguage of a prefix closed K accepted by a deterministic pushdown automaton (DPDA) when the plant language is also prefix closed and accepted by a finite state automaton and 2) in this case, we show that this supremal controllable sublanguage is also accepted by a DPDA.     

<Emphasis Type="Italic">SetExp</Emphasis>: a method of transformation of timed automata into finite state automata

Real-time discrete event systems are discrete event systems with timing constraints, and can be modeled by timed automata. The latter are convenient for modeling real-time discrete event systems. However, due to their infinite state space, timed automata are not suitable for studying real-time discrete event systems. On the other hand, finite state automata, as the name suggests, are convenient for modeling and studying non-real time discrete event systems. To take into account the advantages of finite state automata, an approach for studying real-time discrete event systems is to transform, by abstraction, the timed automata modeling them into finite state automata which describe the same behaviors. Then, studies are performed on the finite state automata model by adapting methods designed for non real-time discrete event systems. In this paper, we present a method for transforming timed automata into special finite state automata called Set-Exp automata. The method, called SetExp, models the passing of time as real events in two types: Set events which correspond to resets with programming of clocks, and Exp events which correspond to the expiration of clocks. These events allow to express the timing constraints as events order constraints. SetExp limits the state space explosion problem in comparison to other transformation methods of timed automata, notably when the magnitude of the constants used to express the timing constraints are high. Moreover, SetExp is suitable, for example, in supervisory control and conformance testing of real-time discrete event systems.     

Supervisory control of partially observed discrete event systems with arbitrary control patterns

In this paper, we study supervisory control of partially observed discrete event systems with arbitrary control patterns. First, we present a necessary and sufficient condition for the existence of a supervisor for a given non-empty and closed language K. Next, we consider the case where the language K does not satisfy the condition. We prove that there always exists its infimal superlanguage for which there exists a supervisor when the set Gamma of control patterns is closed under intersection. This infimal superlanguage is the optimal solution larger than K. On the other hand, when Gamma is closed under union, there does not necessarily exist its supremal sublanguage for which there exists a supervisor. In other words, the optimal solution smaller than K does not exist in general. So, in this case, we present a suboptimal solution smaller than K.     

离散系统输出反馈强正实控制器综合

基于正实引理使用线性矩阵不等式(LMI)方法讨论了离散系统一般强正实控制问 题的解,给出了任意阶输出反馈强正实控制器的存在条件.证明了给定离散系统可输出反 馈强正实当且仅当三个LMI存在一个合适解,可低价输出反馈强正实当且仅当带秩约束条 件的三个LMI存在一个合适解.     

A pseudometric in supervisory control of probabilistic discrete event systems

The focus of this paper is the pseudometric used as a key concept in our previous work on optimal supervisory control of probabilistic discrete event systems. The pseudometric is employed to measure the behavioural similarity between probabilistic systems, and initially was defined as a greatest fixed point of a monotone function. This paper further characterizes the pseudometric. First, it gives a logical characterization of the pseudometric so that the distance between two systems is measured by a formula that distinguishes between the systems the most. A trace characterization of the pseudometric is then derived from the logical characterization, characterizing the similarity between systems from a language perspective. Further, the solution of the problem of approximation of a given probabilistic generator with another generator of a prespecified structure is suggested such that the new model is as close as possible to the original one in the pseudometric. The significance of the approximation is then discussed, especially with respect to previous work on optimal supervisory control of probabilistic discrete event systems.     

Renormalized measure of regular languages

This paper modifies the signed real measure of regular languages, which has been reported in recent literature for analysis and synthesis of discrete event supervisory control laws. A new concept of renormalized measure is introduced to eliminate a user-selectable parameter in the present version of the language measure. The concept of measure renormalization is illustrated by an example.     

On controllability of discrete event systems in a behavioral framework

The purpose of this paper is to investigate the controllability and the achievability of discrete event systems within a behavioral framework. Based on the notion of Willems’ behavioral controllability [1, 2], we introduce a new concept related to the controllability of discrete event systems. By using the controllability proposed here and the notion related to achievable behaviors [3, 4], we show that the behavioral controllability for a given specification with respect to language is equivalent to the existence of a controller, so that an interconnected system satisfies the specification exactly. A proposed controller here is represented by the intersection of the behavior of a given plant and that of a given (controllable) specification. We also clarify that our controllers for a given specification fit the properties of well-known supervisory controllers proposed and developed by Ramadge and Wonham [5]. The text was submitted by the authors in English.