Online Fault Diagnosis in Discrete Event Systems with Partially Observed Petri Nets

International Journal of Control, Automation and Systems - This paper investigates the fault detection problem for Discrete Event Systems (DES) which can be modeled by Partially Observed Petri Nets...     

实时离散事件系统的预测状态反馈控制

本文我们将预测监控的一般结果推广到状态反馈控制的情况。给出了预测状态反馈控制器存在的充要条件及设计方法。对一类特殊的系统,我们证明了任一传统的状态反馈控制下的解也是预测状态反馈控制问题的解,从而预测状态反馈控制对这类系统有最优解存在。最后,我们给出了一个例子来说明这一结果。     

Logical time control of concurrent DES

Discrete Event Dynamic Systems - The synthesis of controllers for reactive systems can be done by computing winning strategies in two-player games. Timed (game) Automata are an appropriate...     

Supervisory controller synthesis and implementation for safety PLCs

Discrete Event Dynamic Systems - The development of supervisory controllers for cyber-physical systems is a laborious and error-prone process. Supervisor synthesis enables control designers to...     

离散事件系统的可测性

讨论基于自动机/形式语言模型的离散事件系统（DES）的可测性问题。可测性即为根据系统的可观事件和状态输出的信息估计系统的当前状态。定义了四种可测性：强可测性,弱可测性,强周期可测性,弱周期可测性。给出了这些可测性的充要条件,这些充要条件可通过构建观测器进行有效的判定。     

Using infinitesimal perturbation analysis of stochastic flow models to recover performance sensitivity estimates of discrete event systems

Stochastic Flow Models (SFMs) form a class of hybrid systems used as abstractions of complex Discrete Event Systems (DES) for the purpose of deriving performance sensitivity estimates through Infinitesimal Perturbation Analysis (IPA) techniques when these cannot be applied to the original DES. In this paper, we establish explicit connections between gradient estimators obtained through a SFM and those obtained in the underlying DES, thus providing analytical evidence for the effectiveness of these estimators which has so far been limited to empirical observations. We consider DES for which analytical expressions of IPA (or finite difference) estimators are available, specifically G/G/1 and G/G/1/K queueing systems. In the case of the G/G/1 system, we show that, when evaluated on the same sample path of the underlying DES, the IPA gradient estimators of states, event times, and various performance metrics derived through SFMs are, under certain conditions, the same as those of the associated DES or their expected values are asymptotically the same under large traffic rates. For G/G/1/K systems without and with feedback, we show that SFM-based derivative estimates capture basic properties of finite difference estimates evaluated on a sample path of the underlying DES.     

线性离散事件动态系统在广义反馈律下的动态特性分析*

基于极大代数,一类离散事件动态系统可被看作为“线性”系统。本文讨论这类系统在广义反馈律下的动态特性,证明了这类系统最终呈现周期性,还研究了系统参数发生摄动时其性能的变化特点,给出了具体例子来解释广义反馈律的物理意义和证实文中结论。     

On the history of Discrete Event Systems

The purpose of this article is to provide a viewpoint of the development of the field of Discrete Event Systems (DES). Necessarily incomplete, because of the breath of topics and richness of research results, this paper is mainly presented from a System Theory-Automatic Control (AC) perspective. Written with a certain emphasis at the dawn of the discipline, the following five articles of this special section of the journal provide essential complements on its evolution along the four last decades. Starting with the identification of three basic threads along which many developments took place, the multidisciplinary and dynamic character of DES and the diversity of formalisms and techniques that are used are stressed.     

A mean field absorbing control model for interacting objects systems

Discrete Event Dynamic Systems - We study a class of discrete-time stochastic systems composed of a large number of N interacting objects, which are classified in a finite number of classes. The...     

Discrete-event systems subject to unknown sensor attacks

Discrete Event Dynamic Systems - This work is set in the context of supervisory control of discrete-event systems under partial observation. Attackers that are able to insert or erase occurrences...     

Due-date quotation model for manufacturing system scheduling under uncertainty

Discrete Event Dynamic Systems - This paper studies the scheduling problem for the manufacturing systems with uncertain job duration, and the possibility of planning due-date quotations for...     

Real-time integrated model for visual perception and fuzzy control

Current state-of-the-art security systems incorporate ‘passive’ and/or ‘human’ elements, the effectiveness of which can only be measured by their ability to ‘deter’ intruders. However, rapidly changing economic and cultural conditions have weakened the strengths associated with such systems. In the not too distant future, the need for an ‘active’ security system will become necessary in order to reduce the onslaught of crime.

This paper presents a conceptual basis for the incorporation of artificial intelligence concepts in the design and implementation of ‘active’ security systems. Specifically, the paper discusses issues pertaining to a real-time model for visual perception and tracking of possible intruders.     

The constituents of business interaction––generic layered patterns

In order to perform business modelling as apart of information systems development, there is a need for frameworks and methods. The paper proposes a framework for business interaction based on a language/action perspective. The framework is an architecture of five generic layers. The first layer concept is ‘business act’, which functions as the basic unit of analysis. The following four layer concepts are ‘action pair’, ‘exchange’, ‘business transaction’, and ‘transaction group’. The framework is inspired by a similar framework constructed by Weigand et al. The paper makes a critical examination of this framework as a basis for the proposed framework.     

Weakly linear systems for matrices over the max-plus quantale

Discrete Event Dynamic Systems - In this paper we introduce and study weakly linear systems, i.e. systems consisting of matrix inequalities Eqs. 17–20, over the max-plus quantale...     

The concept of residuals for fault localization in discrete event systems

In this paper an approach for fault localization in closed-loop Discrete Event Systems is proposed. The presented diagnosis method allows fault localization using a fault-free system model to describe the expected system behavior. Via a systematic comparison of the observed and the expected behavior, a fault can be detected and a set of fault candidates is determined. Inspired by residuals known from diagnosis in continuous systems, different set operations are introduced to generate the fault candidate set. After fault detection and a first fault localization, a procedure is given to render the fault localization more precisely by an analysis of the further observed system behavior. Special emphasis is given to the use of identified models for the fault-free system behavior. The approach is explained using a laboratory manufacturing facility.     

Real-time management of complex resource allocation systems: Necessity,achievements and further challenges

Many contemporary applications, ranging from flexibly automated production systems, to automated material handling and intelligent transportation systems, to internet-based workflow management systems, and more recently, to the massively parallelized software systems that emerge in the context of the novel multi-core computing architectures, can be perceived as a set of finite resources that support a number of concurrently running processes. These processes execute in a staged manner and, at each stage, they vie for the allocation of various subsets of the system resources. To effectively support and manage the extensive levels of concurrency and operational flexibility that are contemplated for these environments, and the ensuing complexity, there is a substantial need for formal models and tools that will enable the modeling, analysis and eventually the control of the aforementioned resource allocation function so that the resulting dynamics are, both, behaviorally correct and operationally efficient. This article overviews a research program that seeks to address the aforementioned need by using the unifying abstraction of the resource allocation system (RAS) and supporting modeling frameworks, like automata, Petri nets, and Markov reward and decision processes, borrowed from the area of Discrete Event Systems (DES) theory. The presented results take advantage of the special structure that exists in the considered RAS classes, and they are characterized by their analytical rigor and computational tractability. The article also highlights the further challenges that must be addressed for the successful completion and promotion of the pursued framework.     

Compositional coordinator synthesis of extended finite automata

Discrete Event Dynamic Systems - To avoid the state-space explosion problem, a set of supervisors may be synthesized using divide and conquer strategies, like modular or multilevel synthesis....     

Nonblocking and deterministic decentralized control for networked discrete event systems under communication delays

Discrete Event Dynamic Systems - Nonblocking is an important issue in supervisory control of discrete event systems. In this paper, we investigate nonblocking control for networked discrete event...     

Modular Fault Diagnosis Based on Discrete Event Systems

An awareness of failure type and location is an indispensable requirement for the establishment of adequate recovery strategies and the maintenance of Factory Automation and Process Control systems.The failure diagnosis methodology presented in this paper is based on Discrete Event Systems models and in the diagnoser concept, which enable the off-line and on-line analysis of systems failures. We present an approach for models and associated diagnosers based on a modular decomposition of the global system, with the aim of avoiding problems of exponential explosion in the number of states and computational complexity of the diagnosis process.