离散事件动态系统多模型集成控制理论

本文讨论现有各种DEDS模型和理论之间的关系以及建立统一的DEDS理论的可能性问题,主要内容包括:DEDS的复杂性以及对它采用多重模型描述和递阶控制结构的必要性;对现有理论模型和控制问题进行综述以揭示它们作为“知识块”看待时其间的相互联系;集成的方法论和为此目的运用人工智能技术的重要性。     

实时离散事件动态系统的状态行为与最速控制

基于Ｄ－自动机模型，通过广义状态谓词空间与半范数的概念，深入研究了实时ＤＥＤＳ的状态行为及最速控制问题，最后讨论了此类控制问题解的存在性。     

离散事件动态系统理论的发展动向

离散事件动态系统(DEDS)是这样一类人造系统,它在每一时间点上的变化发展依赖于许多不同事件的复杂交互作用,其状态仅在离散的时间点上发生变化。这样的系统很多,如制造系统、计算机系统、城市交通系统、排队服务系统、复杂的多模式过程控制系统等。离散事件动态系统理论自1980年由美国哈佛大学著名教授何毓琦(Y.C.Ho)倡导研究以来,已取得了不小进展。十多年后的今天,问题和成果并存,我们对建立这一理论的困难也有了进一步的认识。本文从探索的角度向读者简介一下此理论的发展情况,与计算机科学的联系,潜在的应用问题,及讨论一下此理论目前存在的问题和未来发展方向。本文不     

离散事件动态系统稳定性分析方法

本文提出一种受控时序PETRI网络方法以建立离散事件动态系统状态空间模型,并以此为基础给出一类离散事件系统的稳定性定义及一种新的稳定性分析方法.     

“线性”离散事件动态系统的特征值

本文讨论无环向图和皮特利网描述的一类离散事件动态系统的特征值的求解方法，对事件延迟系统，给出了频域的特征矩阵M（z)的特征值求法，并由之提出一个新的求取闭环无环向图描述的离散系统特征值的方法。     

离散事件动态系统理论及应用

文章从系统分析,模型设计,性能分析,控制与优化等几个方面对离散事件动态系统（Discrete Event Dynamic SYstem,DEDS)的研究与发展状况进行了较为系统的综述,对DEDS与连续变量动态进行了简要的对比分析,并指出了DEDS理论在柔性制造,网络通讯,生产调度等方面的应用。     

离散事件动态系统的结构

提出对离散事件动态系统的结构及组合规律进行研究的问题, 提出离散事件动态系统结构的定义, 提出子系统的两种组合方式并论证了相关的性能保持条件. 利用系统的结构及组合规律, 可以在建模过程中同时考虑控制需求, 避免常规方法的分析困难和综合复杂性, 大幅度减少系统分析和设计过程的开销, 从而为离散事件动态系统监控理论的应用开拓新的途径.     

Near-Optimal Online Control of Dynamic Discrete-Event Systems

A class of time-varying discrete-event systems, named dynamic discrete-event systems, is defined. The goal of this paper is to provide a method which is modular and can be applied in real solutions for the optimization of the online control of such systems. First, a simple control algorithm is presented, followed by illustrative examples of different issues that can arise if it is used. Afterward, a more complicated near-optimal online control algorithm with normalization of string values is proposed. The time variability of the systems is accounted for and the average computational time is drastically reduced. This is demonstrated with a set of simulations of the performance of the new algorithm.     

离散事件动态系统的输出反馈与周期配置

对一类用极大代数描述的离散事件动态系统,本文得到了能用输出反馈任意配置其周期的充分必要条件.证明了一个系统如果能用输出反馈任意配置周期,那么它是能达能观的.     

Invertibility of Discrete-Event Dynamic Systems

In this paper we consider a class of Discrete-Event Dynamic Systems (DEDS) modeled as finite-state automata in which only some of the transition events are directly observed. An invertible DEDS is one for which it is possible to reconstruct the entire event string from the observation of the output string. The dynamics of invertibility are somewhat complex, as ambiguities in unobservable events are typically resolved only at discrete intervals and, perhaps, with finite delay. A notion of resiliency or error recovery is developed for invertibility, and polynomial-time tests for invertibility and for resilient invertibility, as well as a procedure for the construction of a resilient inverter, are discussed.Research supported by the Air Force Office of Scientific Research under Grant AFOSR-88-0032 and by the Army Research Office under Grant DAAL03-86-K0171. This research was partially done during our stay at the Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Rennes, France, and the second author was also supported by IRISA during this time.     

线性控制系统动平衡状态分析

针对含有输入的动力系统的一类平衡状态(不是针对自由系统的某一个平衡点)进行了讨论。这个平衡状态与输入有关,所以被称作动平衡状态。在某些特定条件下,可以得到动平衡状态的表达式。通过推导和证明,建立了在奇异和非奇异两种线性系统下动平衡状态的表达式,同时还提出了动平衡状态可控性的概念和存在的条件。     

基于VB界面的期刊数据库管理系统设计

利用VB中文版的数据库编程技术及其DAO模型在数据库界面编程中的应用,完成了VB界面的期刊数据库管理系统设计。     

一种非线性离散动态投入产出系统的最优控制

阐述了基于动态投入产出模型的最优控制理论,并对当前国内外的研究成果进行了对比研究。在分析其优缺点的同时,针对非线性离散动态投入产出系统的特点,提出了一种动态投入产出系统最优控制的逐次逼近方法。此方法首先将系统的最优控制问题转化为非线性两点边值问题族,然后通过构造线性两点边值问题族,将非线性两点边值问题转化为非齐次线性两点边值问题族;得到的最优控制律由精确控制项和非线性补偿项两部分组成,精确控制项可以通过求解Riccati方程求出其精确解,非线性补偿项由逐次逼近法求解一族线性伴随向量方程的解序列求得;最优控制律的最终目标是在规划期内使实际产出尽可能地与理想产出接近。实验仿真测试表明,采用逐次逼近法获得了非线性离散动态投入产出的最优系统控制,从而为最优控制问题的有效解决提供了参考和借鉴。     

Multitasking Supervisory Control of Discrete-Event Systems

This paper presents an approach for functionally dealing with multiple tasks in the supervisory control of discrete-event systems (DES). The colored marking generator (CMG), a special type of Moore automaton, is introduced as a model that distinguishes classes of tasks in DES. The main results of supervisory control theory are extended to this model, allowing the synthesis of minimally restrictive supervisors, which respect the safety specifications and ensure coreachability of multiple control objectives. Reversibility is also investigated as an alternative way of ensuring liveness of multiple tasks. Two examples illustrate the convenience of this approach.     

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。     

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.     

Modular Control of Discrete-Event Systems With Coalgebra

Modular supervisory control of discrete-event systems, where the overall system is a synchronous (parallel) product of subsystems, is considered. The main results of this paper are formulations of sufficient conditions for the compatibility between the synchronous product and various operations stemming from supervisory control as supervised product and supremal controllable sublanguages. These results are generalized to the case of modules with partial observations: e.g., modular computation of supremal normal sublanguages is studied. Coalgebraic techniques based on the coinduction proof principle are used in our main results. Sufficient conditions are derived for modular to equal global control synthesis. An algorithmic procedure for checking the new conditions is proposed and the computational benefit of the modular approach is discussed and illustrated by comparing the time complexity of modular and monolithic computation.