Petri网的硬件实现

Petri网是异步并发现象建模的重要工具,Petri网的硬件实现将为并行控制器的设计提供有效的途径.给出了几种Petri网系统的硬件实现方法,包括带抑制弧和允许弧的C/E系统、P/T系统、T-时延Petri网系统;给出了硬件实现中非纯网的处理方法.首先讨论实现各种Petri网的逻辑电路;然后用ABEL语言对逻辑电路进行描述;最后给出了一个用解释Petri网描述的服务系统的例子,说明如何使用硬件(CPLD)实现的方法.实验结果表明了上述方法的正确性.这对于离散事件动态系统控制器的设计,尤其是片上并行控制器、多处理器芯片的设计都具有十分重要的意义.  

Min-max functions

A variety of problems in operations research, control theory, computer science, etc., can be modeled as discrete event systems with maximum and minimum constraints. When these systems require only maximum constraints (or, dually, only minimum constraints) they can be studied by linear methods based on max-plus algebra. Systems with mixed constraints, however, are nonlinar from this perspective and relatively little is known about their behaviour. The paper lays the foundations of the theory of discrete event systems with mixed constraints. We introduce min-max functions,F:R ⁿ R ⁿ , which are constructed using finitely many operations of min, max and +, and study them as dynamical systems. Among other results, we give a complete account of the periodic behavior of functions of dimension 2; we introduce and characterize the concept of balance which generalizes irreducibility in the linear theory; and we give a formula for the cycle time (eigenvalue) of a min-max function which generalizes the maximum cycle mean formula.  

Coloured Petri Nets and CPN Tools for modelling and validation of concurrent systems

Coloured Petri Nets (CPNs) is a language for the modelling and validation of systems in which concurrency, communication, and synchronisation play a major role. Coloured Petri Nets is a discrete-event modelling language combining Petri nets with the functional programming language Standard ML. Petri nets provide the foundation of the graphical notation and the basic primitives for modelling concurrency, communication, and synchronisation. Standard ML provides the primitives for the definition of data types, describing data manipulation, and for creating compact and parameterisable models. A CPN model of a system is an executable model representing the states of the system and the events (transitions) that can cause the system to change state. The CPN language makes it possible to organise a model as a set of modules, and it includes a time concept for representing the time taken to execute events in the modelled system. CPN Tools is an industrial-strength computer tool for constructing and analysing CPN models. Using CPN Tools, it is possible to investigate the behaviour of the modelled system using simulation, to verify properties by means of state space methods and model checking, and to conduct simulation-based performance analysis. User interaction with CPN Tools is based on direct manipulation of the graphical representation of the CPN model using interaction techniques, such as tool palettes and marking menus. A license for CPN Tools can be obtained free of charge, also for commercial use.  

Modular supervisory control of discrete-event systems

A modular approach to the supervisory control of a class of discrete-event systems is formulated, and illustrated with an example. Discrete-event systems are modeled by automata together with a mechanism for enabling and disabling a subset of state transitions. The basic problem of interest is to ensure by appropriate supervision that the closed loop behavior of the system lies within a given legal behavior. Assuming this behavior can be decomposed into an intersection of component restrictions, we determine conditions under which it is possible to synthesize the appropriate control in a modular fashion. The work of this author was supported by NSERC (Canada) under Grant No. A-7399. The work of this author was supported by the National Science Foundation through Grant No. ECS-8504584.  

Control Synthesis of Petri Nets Based on S-Decreases

A method for constructing a controller for a discrete event system modeled by a Petri net is presented in this paper. The control specification of the system is given by a set of linear inequality constraints defined on the marking of the net. The controller that forces the net to obey the constraints is an extended Petri net, which is synthesized based on minimal support S-decreases. The method can deal with general Petri nets with uncontrollable transitions, and then provides a systematic way for synthesizing net-based controllers for discrete event systems.  

基于遗传算法的随机性（Q，r）库存系统仿真优化

（Q，r）模型是库存管理中的重要控制模型。对于随机性（Q，r）库存系统，难以用解析方法求解最优的库存控制策略。运用仿真优化技术，基于离散事件系统仿真原理，建立了随机性（Q，r）库存系统的仿真模型，设计了一种改进的遗传算法并应用它优化库存系统的库存控制策略。采用面向对象方法实现了仿真模型和改进的遗传算法。仿真实例表明所提出的仿真优化技术是可行且有效的。  

针对一般线性约束的Petri网控制器设计方法

针对基于Petri网离散事件系统关于标识向量和Parikh向量的不等式约束反馈控制器设计问题,提出一种新的控制器设计方法.该方法首先利用Petri网的状态方程把关于标识向量和Parikh向量的不等式约束转变成关于Parikh向量的不等式约束,然后基于Petri网库所是关于Parikh向量的不等式约束的观点构造控制器.最后将该方法与Iordache和Moody提出的方法作比较,实验结果显示该方法更简单、有效.  

Eigenvalues of dynamic max-min systems

Discrete event dynamic systems are studied in which the time evolution depends on the max-, min-, and the summation operation simultaneously. Specifically, necessary and sufficient conditions are given under which the operator which characterizes the evolution of such a system has an eigenvalue and eigenvector(s). Numerical algorithms to calculate these quantities are also provided.Most of the research described in this paper was done while at École des Mines de Paris in Fontainebleau, Centre d'Automatique et Informatique, France, during the summer of 1989.  

On the control of discrete-event dynamical systems

We study a class of problems related to the supervisory control of a discrete-event system (DES), as formulated by Ramadge and Wonham, and we focus on the computational effort required for their solution. While the problem of supervisory control of a perfectly observed DES may be easily solved by dynamic programming, the problem becomes intractable (in the sense of complexity theory) when imperfectly observed systems are considered. Research supported by the Army Research Office (Grant No. DAAL03-86-K-0171) and by an NSF PYI award, with matching funds from Bellcore Inc.  

自主车的局部路径规划

局部路径规划是自主车的一项关键技术，它的品质 密切关系到整个自主车系统的性能．本文提出了将自主式多智能体的任务和反应性行为模型 嵌入到离散事件系统框架中作局部路径规划的方法，此方法克服了势场法（包括早期的虚力 场法）的缺陷——即由于把所有信息压缩为单个合力而损失部分有价值的局部障碍物分布信 息，从而提高了局部路径规划的可靠性．