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For bounded Petri nets, Cabasino et al. propose a diagnosability test method that is based on the analysis of a modified basis reachability graph and a basis reachability diagnoser. However, its complexity is exponential in the number of nodes of the basis reachability diagnoser. In order to reduce the complexity of their method, this paper presents a new diagnosability test approach for bounded Petri nets. We present the concept of an extended basis reachability graph and prove that our approach is of polynomial complexity in the number of nodes of extended basis reachability graphs. An example is given to illustrate the application of the presented approach. 相似文献
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Discrete event diagnosis using labeled Petri nets. An application to manufacturing systems 总被引:2,自引:0,他引:2
In this paper an approach to on-line diagnosis of discrete event systems based on labeled Petri nets is presented. The approach is based on the notion of basis markings and justifications and it can be applied both to bounded and unbounded Petri nets whose unobservable subnet is acyclic. Moreover it is shown that, in the case of bounded Petri nets, the most burdensome part of the procedure may be moved off-line, computing a particular graph called Basis Reachability Graph.Finally, the effectiveness of the proposed procedure is analyzed applying a MATLAB diagnosis toolbox we developed to a manufacturing example taken from the literature. 相似文献
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On‐the‐Fly and Incremental Technique for Fault Diagnosis of Discrete Event Systems Modeled by Labeled Petri Nets 下载免费PDF全文
In this paper, we develop an on‐the‐fly and incremental technique for fault diagnosis of discrete event systems modeled by labeled Petri nets, in order to tackle the combinatorial explosion problem. K‐diagnosability, diagnosability, Kmin (the minimum K ensuring diagnosability) and on‐line diagnosis are solved on the basis of the on‐the‐fly and incremental building of two structures, called respectively fault marking graph and fault marking set graph, in parallel. We build on existing results, namely those establishing necessary and sufficient conditions for diagnosability, but we bring mechanisms to make the checking of such conditions potentially more efficient. We show that, in general, analyzing or even building the whole reachability graph is unnecessary to analyze diagnosability and build an on‐line diagnoser. Our technique was implemented in a prototype tool called OF‐PENDA, and a railway level crossing benchmark is used to make a comparative discussion pertaining to efficiency in terms of time and memory relative to some existing approaches. 相似文献
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In this paper, we show that (1) the question to decide whether a given Petri net is consistent, Mo-reversible or live is reduced to the reachability problem in a unified manner, (2) the reachability problem for Petri nets is equivalent to the equality problem and the inclusion problem for the sets of all firing sequences of two Petri nets, (3) the equality problem for the sets of firing sequences of two Petri nets with only two unbounded places under homomorphism is undecidable, (4) the coverability and reachability problems are undecidable for generalized Petri nets in which a distinguished transition has priority over the other transitions, and (5) the reachability problem is undecidable for generalized Petri nets in which some transitions can reset a certain place to zero marking. 相似文献
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Fault detection for discrete event systems using Petri nets with unobservable transitions 总被引:1,自引:0,他引:1
Maria Paola Cabasino Author Vitae Alessandro Giua Author Vitae Author Vitae 《Automatica》2010,46(9):1531-1539
In this paper we present a fault detection approach for 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. Our diagnosis approach is based on the notions of basis marking and justification, that allow us to characterize the set of markings that are consistent with the actual observation, and the set of unobservable transitions whose firing enable it. This approach applies to all net systems whose unobservable subnet is acyclic. If the net system is also bounded the proposed approach may be significantly simplified by moving the most burdensome part of the procedure off-line, thanks to the construction of a graph, called the basis reachability graph. 相似文献
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Notomi M. Murata T. 《IEEE transactions on pattern analysis and machine intelligence》1994,20(5):325-336
Petri nets have been proposed as a promising tool for modeling and analyzing concurrent-software systems such as Ada programs and communication protocol software. Among analysis techniques available for Petri nets, the most general approach is to generate all possible states (markings) of the system in a form of a so-called reachability graph. However, this conventional reachability graph approach is inefficient or intractable, even for a bounded Petri net, due to state explosion in many practical applications. To cope with this problem, this paper proposes a method for constructing a hierarchically organized state space called the hierarchical reachability graph (HRG). Using the HRG, we obtain necessary and sufficient conditions for reachability and deadlock, as well as algorithms to test whether a given state or marking is reachable from the initial state and whether there is a deadlock state (a state with no successor states) 相似文献
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Petri网和有限自动机是离散事件动态系统的两类主要研究内容.而Petri网系统的能观性分析与判别是基于Petri网的实际系统设计、优化、监测及控制的重要基础.以往关于Petri网能观测性的研究缺乏定量化的充要判别条件.本文利用代数矩阵方法研究了带有输出的有界Petri网系统的能观性问题.首先,基于矩阵的半张量积,将带有输出的有界Petri网系统的动态行为以线性方程组的形式建立了数学模型.然后,针对初始标识和当前标识,介绍了两种能观性定义.最后,基于矩阵运算建立了关于有界Petri网系统能观性的几个充分必要条件,并给出严格证明.数值算例验证了理论结果.本文提出的方法实现了有界Petri网系统能观性的矩阵运算,易于计算机实现. 相似文献
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Yu Ru Maria Paola Cabasino Alessandro Giua Christoforos N. Hadjicostis 《Discrete Event Dynamic Systems》2014,24(3):275-307
In this paper, we consider the forbidden state problem in discrete event systems modeled by partially observed and partially controlled Petri nets. Assuming that the reverse net of the uncontrollable subnet of the Petri net is structurally bounded, we compute a set of weakly forbidden markings from which forbidden markings can be reached by firing a sequence of uncontrollable/unobservable transitions. We then use reduced consistent markings to represent the set of consistent markings for Petri nets with structurally bounded unobservable subnets. We determine the control policy by checking if the firing of a certain controllable transition will lead to a subsequent reduced consistent marking that belongs to the set of weakly forbidden markings; if so, we disable the corresponding controllable transition. This approach is shown to be minimally restrictive in the sense that it only disables behavior that can potentially lead to a forbidden marking. The setting in this paper generalizes previous work by studying supervisory control for partially observed and partially controlled Petri nets with a general labeling function and a finite number of arbitrary forbidden states. In contrast, most previous work focuses on either labeling functions that assign a unique label to each observable transition or forbidden states that are represented using linear inequalities. More importantly, we demonstrate that, in general, the separation between observation and control (as considered in previous work) may not hold in our setting. 相似文献
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Mu Der Jeng Mao Yu Peng 《IEEE transactions on systems, man, and cybernetics. Part A, Systems and humans : a publication of the IEEE Systems, Man, and Cybernetics Society》1999,29(2):173-183
An augmented reachability tree (ART) is proposed to extend the capability of the classical reachability tree (RT) for analyzing qualitative properties, such as liveness, of a class of unbounded generalized Petri nets, called 1-place-unbounded nets, where there is at most one unbounded place for each net. The idea is based on the computation of the minimal marking of each node in the tree. An algorithm for obtaining the minimal marking is shown. Examples are given to illustrate the technique. In addition to liveness, the proposed method can verify other properties such as reversibility and feasible firing sequences. Furthermore, properties verifiable by RT are also verifiable by ART 相似文献
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Possibilistic Petri nets 总被引:5,自引:0,他引:5
Cardoso J. Valette R. Dubois D. 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》1999,29(5):573-582
This paper presents the possibilistic Petri net model which combines possibility logic with Petri nets with objects. The main feature of this model is to allow one to reason about the aspects of uncertainty and change in dynamic discrete event systems. The paper presents relevant concepts of Petri nets with objects and possibility logic and how imprecision and vagueness are introduced in the marking of a Petri net with objects. The marking of a net is imprecise, or in a more general way, fuzzy, in order to represent an ill-known knowledge about a system state. A new marking updating according to the fuzzy marking such defined is also discussed. An example of shop door monitoring is presented that illustrates our approach. 相似文献
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The problem of the synthesis of time bounds enforcing good properties for reactive systems has been much studied in the literature. These works mainly rely on dioid algebra theory and require important restrictions on the structure of the model (notably by restricting to timed event graphs). In this paper, we address the problems of existence and synthesis of shrinkings of the bounds of the time intervals of a time Petri net, such that a given property is verified. We show that this problem is decidable for CTL properties on bounded time Petri nets. We then propose a symbolic algorithm based on the state class graph for a fragment of CTL. If the desired property “includes” k-boundedness, the proposed algorithm terminates even if the net is unbounded. A prototype has been implemented in our tool Romeo and the method is illustrated on a small case study from the literature. 相似文献
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Observability of place/transition nets 总被引:1,自引:0,他引:1
We discuss the problem of estimating the marking of a place/transition (P/T) net based on event observation. We assume that the net structure is known while the initial marking is totally or partially unknown. We give algorithms to compute a marking estimate that is a lower bound of the actual marking. The special structure of Petri nets allows us to use a simple linear algebraic formalism for estimate and error computation. The error between actual marking and estimate is a monotonically nonincreasing function of the observed word length, and words that lead to error are said to be complete. We define several observability properties related to the existence of complete words, and show how they can be proved. To prove some of them, we also introduce a useful tool, the observer coverability graph, i.e., the usual coverability graph of a P/T net augmented with a vector that keeps track of the estimation error on each place of the net. Finally, we show how the estimate generated by the observer may be used to design a state feedback controller for forbidden marking specifications. 相似文献
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T-组合Petri网的活性和公平性分析 总被引:1,自引:0,他引:1
同步合成是研究复杂Petri网系统性质的有效途径.文中通过引入可引发变迁序偶的概念,研究了T-组合(同步合成)Petri网对子网的活性和公平性继承关系,给出了一组T-组合Petri网活或公平的充要条件和充分条件.这些结果对网组合同步设计具有重要的指导意义 相似文献
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ZhiJun Ding ChangJun Jiang MengChu Zhou 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2008,38(3):881-883
A deadlock-checking approach for one-place unbounded Petri nets is presented based on modified reachability trees (MRTs). An MRT can provide some useful information that is lost in a finite reachability tree, owing to MRT's use of the expression a + bn(i) rather than symbol omega to represent the value of the components of a marking. The information is helpful to property analysis of unbounded Petri nets. For the deadlock-checking purpose, this correspondence paper classifies full conditional nodes in MRT into two types: true and fake ones. Then, an algorithm is proposed to determine whether a full conditional node is true or not. Finally, a necessary and sufficient condition of deadlocks is presented. Examples are given to illustrate the method. 相似文献
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Lefebvre D. El Moudni A. 《IEEE transactions on systems, man, and cybernetics. Part A, Systems and humans : a publication of the IEEE Systems, Man, and Cybernetics Society》2001,31(3):153-162
Petri nets (PNs) are useful tools for the modeling and analysis of discrete event systems. This work deals with the estimation of firing and enabling sequences for timed transition PNs with unknown time delays. The marking and reserved marking of the places are measured online. The estimation problem has exact and approximated solutions that are described. Sufficient conditions are given on the measurement accuracy of the marking and reserved marking vectors, so that the estimation of firing and enabling sequences is an exact one. If the estimation provides several solutions, the PN is extended in order to give a unique solution. Numerical aspects of the estimation are also investigated. As a consequence of this, the proposed method provides interesting tools for the modeling, performance analysis, and above all the monitoring of manufacturing systems and road traffic networks 相似文献