From Mutually Non-Blocking to Switched Non-Blocking DES

National audienceThe mutually non-blocking property of discrete-event systems has been introduced by Fabian and Kumar (1997). In this paper, we extend the property of mutually non-blocking from 2 to 3 elements. We also propose a definition of switched non-blocking system, and we show the mutually non-blocking property is included in the switched non-blocking property. We illustrate the result with an example of protocol conversion with switched specification.La propriété de système à événements discrets mutuellement non-bloquants a été introduite par Fabian and Kumar (1997). Dans ce papier, nous proposons une extension de cette propriété de 2 à 3 éléments. Nous donnons ensuite une définition de système non-bloquant par commutations, et nous montrons que la propriété "mutuellement non-bloquant" est incluse dans celle de "non-bloquant par commutations". Nous illustrons ce resultat à travers un exemple de système de conversion de protocole, dans lequel le protocole commute entre deux spécifications

APPLICATION DU PARADIGME HOLONIQUE A UN SYSTEME DE RESERVOIRS

Colloque avec actes et comité de lecture. internationale.International audienceLe paradigme holonique a été largement étudié dans le cadre de la production manufacturière. Ces productions sont de type discrètes, car les opérations incluses dans les gammes ne mettent pas en jeu de variables à évolution continue. Une classe différente de systèmes est étudiée ici, les systèmes hybrides, qui englobe l’ensemble des systèmes ayant une évolution continue par morceaux, et dont les changements sont liés à l’évolution de variables discrètes. Dans ce cas, une reconfiguration du système est généralement nécessaire, et le paradigme holonique est une réponse pertinente au besoin de flexibilité en découlant. Ce papier propose l’adaptation d’une architecture de référence connue de la littérature discrète au cas des systèmes hybrides. Le modèle proposé est composé de l’union du modèle hybride et du modèle holonique, où le contrôleur proposé est représenté par l’holon Produit et l’holon Ordre, l'interface est représentée par la partie logique du holon Ressources et le système de production est représenté par la partie physique du holon ressource. La spécification d’holon produit utilisée est orientée services, et la spécification d’holon ressource est une abstraction de la partie physique de la ressource contenant tous les modèles de conversion d’état discret vers l’état continu et vice-versa. Un cas d’étude s’appuyant sur un système de commutations d’arrivées a été choisi

Commande de Systèmes Hybrides et de Systèmes à Evènements Discrets

Cette Thèse d’Habilitation à Diriger des Recherches (HDR) est effectuée dans le cadre de l’Automatique en général. Elle comporte trois parties distinctes. La première partie concerne la commande des systèmes hybrides et systèmes à commutations (switched systems). La deuxième partie est consacrée à la commande supervisée (supervisory control) des systèmes à événements discrets (discrete-event systems). Enfin les perspectives de recherche sont données dans la troisième et dernière partie.La commande des systèmes hybrides et à commutations traite de la modélisation MLD (Mixed Logical Dynamical Systems) introduite par A. Bemporad et M. Morari (1999).Les systèmes à commutations étant décrits naturellement par un modèle PWA (piecewise affine, affine par morceaux), l’approche MLD est une modélisation alternative. Nous proposons des algorithmes de conversion de PWA vers MLD et vice-versa qui donnent des meilleurs résultats, notamment en temps de simulation.La stabilité d’un système non linéaire à commutations est étudiée en utilisant une approche polynomiale, qui permet de reformuler le système initial en un système continu polynomial, permettant ainsi de prouver sa stabilité Enfin la commande optimale est appliquée aux deux types de systèmes commutés : le cas linéaire et celui non linéaire sont traités par reformulation du système en système polynomial continu, permettant d’utiliser la théorie des moments, qui rend les problèmes de commande optimale plus faciles à résoudre.La deuxième partie concerne les systèmes à événements discrets. Elle a débuté avec la commande supervisée de la cellule flexible de l’EMN, composée d’un convoyeur central et de plusieurs stations robotisées (ISIC 2003, LSS 2004). Ensuite influencé par le thème de recherche des systèmes hybrides et systèmes à commutations (switched systems) venant de l’Automatique continue, nos travaux se sont orientés vers une tentative de définition formelle des SED à commutations (switched DES, MTNS 2006). Toujours dans cette voie, nous avons proposé une définition de systèmes “switched non blocking » (MSR 2013), pour arriver à des systèmes avec plusieurs langages pouvant commuter (switchable languages), suivant le modèle de (Kumar, Takai, Fabian et Ushio, 2005).La troisième et dernière partie est consacrée aux perspectives de recherche. La première perspective concerne la commande optimale de “smart grids”, en exploitant la topologie de commutations (switched topology) dans de tels systèmes. La deuxième perspective traite de la simulation et l’optimisation de systèmes logistiques (le système de tri de bagages Air France à l’Aéroport de Paris-CDG) à l’aide de réseaux de Petri

On Switchable Languages of Discrete-Event Systems with Weighted Automata

International audienceThe notion of switchable languages has been defined by Kumar, Takai, Fabian and Ushio in [11]. It deals with switching supervisory control, where switching means switching between two specifications. In this paper, we first extend the notion of switchable languages to n languages, (n ≥ 3). Then we consider a discrete-event system modeled with weighted automata. The use of weighted automata is justified by the fact that it allows us to synthesize a switching supervisory controller based on the cost associated to each event, like the energy for example. Finally the proposed methodology is applied to a simple example

Feedback Stabilization of Switched Differential Algebraic Systems

International audienceA stabilization problem for a switched differential-algebraic system is investigated. We propose an approach for solving effectively the stabilization problem for an autonomous linear switched differential-algebraic system based on projector and flow matrices. In switched DAEs, the switches can induce jumps in certain state-variables, and it has been shown that the formulation as a switched DAE already implicitly defines these jumps, no additional jump map must be given. These jumps can be calculated in terms of the consistency projectors. The essence of this method is to design a stabilizing controller for switched differential-algebraic systems, i.e., the continuous dynamics of each subsystem are described by sets of differential-algebraic equations, using an averaging switched DAE model based on consistency projector and flow matrices to guarantee convergence towards an equilibrium point via fast switchin

Distributed Building Temperature Control with Power Constraints

13th European Control Conference (ECC), Univ Strasbourg, Strasbourg, FRANCE, JUN 24-27, 2014International audienceGenerally, heating, cooling and air conditioning (HVAC) systems are designed to handle worst case loads, and this over-design of HVAC equipment is one of the main reasons for building energy inefficiency. When the HVAC system is not over-designed, there exists a trade-off between the comfort of the building's occupants and the available heating/cooling power at critical load hours. We propose a distributed approach that maximizes the comfort of the building's occupants under several power constraints. We prove by means of graph theoretical tools and passivity analysis, that the proposed controller asymptotically reaches an optimal equilibrium without the need of full information. Finally, some simulations and comparisons are presented to illustrate the performance of our method

Modeling and Simulation of Air France Baggage-Handling System with Colored Petri Nets

International audienceBaggage-Handling System (BHS) is a complex system that deals with many factors such as quantity of the bags, interval of arrivals, barcode misreads, early bags and late bags, traveling time and security check. The main role of BHS is to sort and transport all transfer and check-in bags to each destination, that is to the right plane, at the right time. The airport which has the authority to handle BHS has to minimize the number of failed bags in the system. A failed bag means a bag that does not arrive in time for the assigned flight. Figure 1: Paris-CDG Airport (Terminal N.2) Colored Petri Nets (CPNs) extend the classical Petri net formalism with data, time, and hierarchy. These extensions makes it possible to model complex processes like BHS. Furthermore, CPNs are supported by CPN Tools – a powerful toolset that allows the design and analysis of complex processes. This poster will present a part of large airport's BHS modeling and simulation who deals with more than 20,000 bags per day using CPN Tool. In the real system, barcode is used to keep the unique information on each bag such as time entering the system, assigned flight, and destination gate. This information is interpreted by color set as attributes for each bag in CPN Tool. These attributes are used to sort the bags whether they must go to manual scanning, storage, or directly to destination gate. Sorting is performed by the guard in transition. The main attribute for each entity is the remaining time for assigned flight and the Key Performance Index (KPI) is the percentage of failed bags which have never been considered by simulation papers which do not deal with routing problem. The majority of the papers on BHS focuses on throughput of the system, average time in system, queue size, or waiting time. In this work, we analyze each factor and define the factors which have substantial effect to the system performance. At the end, it will propose the best strategy to minimize the percentage of failed bags

Modeling and Simulation of Baggage Handling System in A Large Airport

ISBN 978-602-50913-0-8International audienceBaggage Handling System (BHS) is a complex system because many factors are involved such as quantity of the bags, interval of arrivals, barcode misreads, early bags and late bags, traveling time and security check. The main role of BHS is to sort and transport all transfer and check-in bags to each destination based on the time window. The airport which has the authority to handle BHS should ensure there is no failed bag in the system. Failed bag means it does not arrive in time for the assigned flight. Petri net was introduced for illustrating relations between conditions or situations and events. Petri net is a powerful tool for modeling because behavior comprising concurrency, synchronization and resource sharing can be modeled and visualized. Colored Petri Net (CPN) is a special type of Petri net which is enriched by color set to define discrete data types and set of expressions for the initial marking, guards and arc inscriptions. It has been used for modeling various systems such as manufacturing, robotic, transportation, etc. This paper will do a part of large airport's BHS modeling and simulation which deals with more than 20,000 bags per day using CPN

A centre–free approach for resource allocation with lower bounds

<p>Since complexity and scale of systems are continuously increasing, there is a growing interest in developing distributed algorithms that are capable to address information constraints, specially for solving optimisation and decision-making problems. In this paper, we propose a novel method to solve distributed resource allocation problems that include lower bound constraints. The optimisation process is carried out by a set of agents that use a communication network to coordinate their decisions. Convergence and optimality of the method are guaranteed under some mild assumptions related to the convexity of the problem and the connectivity of the underlying graph. Finally, we compare our approach with other techniques reported in the literature, and we present some engineering applications.</p

A polynomial approach for optimal control of switched nonlinear systems

International audienceOptimal control problems for switched nonlinear systems are investigated. We propose an alternative approach for solving the optimal control problem for a nonlinear switched system based on the theory of moments. The essence of this method is the transformation of a nonlinear, nonconvex optimal control problem, that is, the switched system, into an equivalent optimal control problem with linear and convex structure, which allows us to obtain an equivalent convex formulation more appropriate to be solved by high-performance numerical computing. Consequently, we propose to convexify the control variables by means of the method of moments obtaining semidefinite programs. Copyright (C) 2013 John Wiley & Sons, Ltd