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The use of Petri nets for the modelling of discrete-event systems is well-studied. Yet, the tools allowing the implementation of these models, and supporting code generation, are still very few, almost non-existent. This paper starts by presenting a Petri net class, based on place/transition nets and well-known concepts from synchronised and interpreted Petri nets. This Petri net class allows the...
This paper presents the planned and on-going activities inside the FORDESIGN research project, funded by the Portuguese FCT (Foundation for Science and Technology), whose main objective is to foster the effective use of formal methods for embedded systems co-design. The project proposes a methodology where the use-cases are used as a starting point, not only for capturing requirements but also to...
The maintenance of systems involved in production processes must be carried out with maximum efficiency and minimum downtime, especially on time-critical systems (operation times are included between a minimum and a maximum value). This paper presents a proactive/reactive control to fit preventive maintenance into a busy production schedule. As preventive maintenance is regarded as a non-preemptive...
In the present work, an innovative nonlinear controller of nonholonomic mechanical systems, characterized by a dynamic not well known model a priori, using a new neural model obtained by the combination of a Petri net with a neural network is proposed. The performances of the control algorithm are evaluated for tasks of tracking of time trajectories. The study of the stability of the total system...
The paper addresses the problem of modelling a FMS with random recipes and controlling it with an agent-based architecture. One of the features of the system are the random recipes, i.e. recipes that are unknown a priori for the control system, which represent a high flexible-routing class of FMS. In particular, a PN model able to represent both the mechanism of generation of random recipes and then...
The increasing complexity of productive systems associated with the geographical dispersion of industries motivates new demands and the adoption of new design tools. In this context the purpose of this work is to introduce a new platform for distributed modeling and analyses of productive systems. The platform is based on Petri net as a modeling formalism and on the label-ring protocol for managing...
This paper discusses a new approach to the development life-cycle of agent-based production control applications, from the design to the operation, based in a catalogue of high-level Petri nets. The high-level Petri net-based approach facilitates the conception, definition and formal specification of an "encapsulation process" in industrial production systems. The catalogue includes elements...
This paper is a contribution to define a complete and modular model of processes in container terminals, which can be used for simulation, test, monitor and control purposes. A schematic description of the main terminal processes is given, by specifying the resources handling containers in the Taranto container terminal. Then a Petri net formalizes the sequence of operations, each involving the synchronization...
In the paper the method of computation all deadlocks and traps in the Petri net is presented. This method is based on Thelen method. Methods of calculation of all deadlocks and traps in Petri nets are very time consuming. Therefore it is very important to optimize a computation. The parallel computation method for the time reduction is proposed. Experimental results of presented method are discussed,...
The paper proposes a dependability model which enables the evaluation of Profibus-DP networks in scenarios of transient faults which affect data communications. The full behavior of Profibus-DP communication stack is modeled, including: cyclic process data exchange between master and slave stations; configuration, parameterization and diagnostics of slave stations. The model is based on a high level...
In this paper we deal with the problem of determining a set of decentralized controllers for P/T nets that are able to impose a given global specification on the net behaviour. More precisely, both the global specification and the decentralized specifications are given in terms of generalized mutual exclusion constraints (GMECs) thus the controllers take the form of monitor places. In this paper we...
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