A novel approach to fault diagnosis of discrete event systems is presented in this paper. The standard approach is based on the offline computation of the set of fault events that may have occurred at each reachable state, providing a fast online diagnosis at a price of excessive memory requirements. A different approach is here adopted, which is based on the online computation of the set of possible fault events required to explain the last observed event. This is efficiently achieved by modelling the plant by Petri nets, since their mathematical representation permits to formulate the fault diagnosis problems in terms of mathematical programming, which is a standard tool. Moreover, the graphical representation of the net allows the diagnoser agent to compute off-line reduced portions of the net in order to improve the efficiency of the online computation, without a big increase in terms of memory requirement.
This paper studies online fault detection and isolation of modular dynamic systems modeled as sets of place-bordered Petri nets. The common places among the set of Petri nets modeling a system capture coupling of various system components. The transitions are labeled by events, some of which are unobservable (i.e., not directly recorded by the sensors attached to the system). The events whose occurrence must be diagnosed have unobservable transition labels. These events model faults or other sig...
This paper discusses the forbidden state problem, as specified by generalized mutual exclusion constraints, in the context of supervisory control of discrete event systems modelled by Petri nets. The case of backward-conflict-free and free-choice uncontrollable subnets is considered and it is shown how to transform such subnets in well-formed free-choice nets. Then, the well-formed free-choice nets are decomposed in marked graph components by recurring to minimal T-invariants. The forbidden stat...
This paper is concerned with an online model-based fault diagnosis of discrete event systems. The model of the system is built using the interpreted Petri nets (IPN) formalism. The model includes the normal system states as well as all possible faulty states. Moreover, it assumes the general case when events and states are partially observed. One of the contributions of this work is a bottom-up modeling methodology. It describes the behavior of system elements using the required states variables...
Abstract This paper studies the problem of predicting occurrences of a significant event in a discrete-event system. The predictability of occurrences of an event in a system is defined in the context of formal languages. The predictability of a language is a stronger condition than the diagnosability of the language. An implementable necessary and sufficient condition for predictability of occurrences of an event in systems modeled by regular languages is presented.
In this note, we develop algebraic approaches for fault identification in discrete-event systems that are described by Petri nets. We consider faults in both Petri net transitions and places, and assume that system events are not directly observable but that the system state is periodically observable. The particular methodology we explore incorporates redundancy into a given Petri net in a way that enables fault detection and identification to be performed efficiently using algebraic decoding t...
In this paper we present an efficient approach for the fault detection of discrete event systems using Petri nets. We assume that some of the transitions of the net are unobservable, including all those transitions that model faulty behaviors. We prove that the set of all possible firing sequences corresponding to a given observation can be described as follows. First a set of basis markings corresponding to the observation are computed together with the minimal set of transitions firings that j...
In this paper we deal with the problem of estimating the marking of a labeled Petri net system based on the observation of transitions labels. In particular, we assume that a certain number of transitions are labeled with the empty string /spl epsi/, while a different label taken from a given alphabet is assigned to all the other transitions. Transitions labeled with the empty string are called silent because their firing cannot be observed. Under some technical assumptions on the structure of t...
A state-based approach for online passive fault diagnosis in systems modeled as finite-state automata is presented. In this framework, the system and the diagnoser (the fault detection system) do not have to be initialized at the same time. Furthermore, no information about the state or even the condition (failure status) of the system before the initiation of diagnosis is required. The design of the fault detection system, in the worst case, has exponential complexity. A model reduction scheme ...
In this paper, we consider the diagnosis of asynchronous discrete event systems. We follow a so-called true concurrency approach, in which no global state and no global time is available. Instead, we use only local states in combination with a partial order model of time. Our basic mathematical tool is that of net unfoldings originating from the Petri net research area. This study was motivated by the problem of event correlation in telecommunications network management.
#1Ahmed Al-Ajeli(College of Information Technology)H-Index: 2
#2David Parker(University of Birmingham)H-Index: 72
Abstract null null We propose techniques for fault diagnosis in discrete-event systems modelled by labelled Petri nets, where fault events are modelled as unobservable transitions. The proposed approach combines an offline and an online algorithm. The offline algorithm constructs a diagnoser in the form of sets of inequalities that capture the legal, normal and faulty behaviour. To implement the offline algorithm, we adopt the Fourier–Motzkin method for elimination of variables from these sets o...
#1Kuize Zhang(Technical University of Berlin)H-Index: 13
#2Jörg Raisch(Technical University of Berlin)H-Index: 29
In this paper, \emph{diagnosability} is characterized for a labeled max-plus automaton \mathcal{A}^{\mathcal{D}}over a dioid \mathcal{D}as a real-time system. In order to represent time elapsing, a special class of dioids called \emph{progressive} are considered, in which there is a total canonical order, there is at least one element greater than \textbf{1} the product of sufficiently many elements greater than \textbf{1}is arbitrarily large, and the cancellative law is satisfied. T...
Last. Claudio Sterle(University of Naples Federico II)H-Index: 10
view all 3 authors...
Security of distributed control systems is affected by the presence of information leaks, which permit to external intruders to infer the state of the system itself. Noninterference deals with the absence of such leak paths in a dynamic system modeled as discrete-event system. For a system that presents information leaks, a supervisory control strategy to enforce noninterference is proposed in this article. The approach is based on the solution of optimization problems on a Petri net model of th...
#2Yuting Li(MUST: Macau University of Science and Technology)H-Index: 2
Last. Zhiwu Li(MUST: Macau University of Science and Technology)H-Index: 63
view all 5 authors...
Abstract Resilience is a critical criterion to evaluate a networked system including discrete-event systems (DESs). This research touches upon the supervisory control problem of a DES modeled with labeled Petri nets under malicious attacks. Attacks on a system can be categorized into actuator attacks and sensor attacks. The former may cause an actuator to fail to execute the commands issued from a supervisor that enforces a specification. The latter may attack a sensor to corrupt an observation ...
Last. João Carlos Basilio(UFRJ: Federal University of Rio de Janeiro)H-Index: 17
view all 4 authors...
Abstract Detection of abnormality (or faults) occurrences is of paramount importance in smart manufacturing systems of Industry 4.0 since faults do not usually take the system immediately to a halt, and so, it can jeopardize an entire production. With that in mind, we propose here an online diagnoser based on the Petri model of either a specific machine or part of a smart manufacturing system that makes its decision regarding the fault occurrence by storing the sequence of observed events and, a...
Last. Naiqi Wu(MUST: Macau University of Science and Technology)H-Index: 49
view all 4 authors...
In this article, we present a fault diagnosis approach for discrete event systems using labeled Petri nets. In contrast to the existing works, a new fault class containing all the fault transitions is additionally introduced in the diagnosis function, leading to a more informative and precise diagnosis result. An integer linear programming (ILP) problem is built according to an observed word. By specifying different objective functions to the ILP problem, the diagnosis result is obtained without...
Various aspects of privacy and safety in many application domains can be assessed based on proper analysis of successive measurements that are collected about a given system. This work is devoted to such issues in the context of timed stochastic discrete event systems (DES) that are modeled with partially observed timed stochastic Petri net models. The first contribution is to introduce a k-step trajectory-observer, which is a construction that captures all possible k-suffixes of the trajectorie...
This paper concerns the diagnosis of faults for stochastic discrete event systems that behave according to non-Markovian dynamics. {k}-bounded partially observed Petri nets are used to model the system structure and the sensors. Stochastic processes with probability density functions (pdf) of finite support define the dynamics. Structural and temporal faults are considered. Structural faults correspond to specific sequences of events that should satisfy precedence conditions defined with patt...
Last. Su Hongye(ZJU: Zhejiang University)H-Index: 12
view all 3 authors...
This study proposes a fault diagnosis method of discrete event systems on the basis of a Petri net model with partially observable transitions. Assume that the structure of the Petri net model and the initial marking are known, and the faults can be modeled by its unobservable transitions. One of the contributions of this work is the use of the structure information of Petri net to construct an online fault diagnoser which can describe the system behavior of normal or potential faults. By modeli...
