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Papers by ghassen cherif
Journal of Control, Automation and Electrical Systems, Mar 3, 2021
This paper is about scheduling problems for a class of flexible manufacturing systems (FMS) that ... more This paper is about scheduling problems for a class of flexible manufacturing systems (FMS) that have some operations with total precedence constraints and other operations with full routing flexibility (namely hybrid FMS). The objective is to find a control sequence from an initial state to a reference one in minimal time. For that, a systematic multi-level formalism is introduced to model the hybrid FMS based on the hierarchical structuration of the operations. Transition-timed Petri nets (T-TPN) that behave under earliest firing policy are used for that purpose. Then a new cost function is introduced to estimate the residual time to the reference. This estimation is proved to be a lower bound of the true duration. A modified Beam Search algorithm is proposed that uses the cost function to selectively explore the Petri net (PN) state space. Computational experiments illustrate the efficiency of the approach in comparison with other existing methods.
Journal of Intelligent Manufacturing, Aug 25, 2021
Proceedings of the 2023 10th International Conference on Industrial Engineering and Applications
2022 8th International Conference on Control, Decision and Information Technologies (CoDIT)
Cette thèse concerne les problèmes d'ordonnancement pour une classe de systèmes manufacturier... more Cette thèse concerne les problèmes d'ordonnancement pour une classe de systèmes manufacturiers flexibles (FMS) en environnement incertain. Les systèmes considérés répondent aux exigences de l’industrie 4.0 qui requièrent des organisations plus agiles permettant de proposer des produits personnalisés. Plus précisément, les systèmes proposés dans ce travail sont appelés FMS hybrides et traitent les opérations avec des contraintes de précédence partielles entre les opérations. La première contribution est une approche systématique de modélisation des FMS hybrides avec les réseaux de Petri temporisés sur les transitions (T-TPN) et un formalisme multi-niveaux basé sur la structuration hiérarchique des opérations. La deuxième contribution concerne la recherche d’ordonnancements pour les FMS hybrides. Nous utilisons la recherche en faisceau et proposons une fonction coût basée sur la modélisation multiniveaux. Nous proposons également une nouvelle variante de la recherche en faisceau, ...
2019 18th European Control Conference (ECC), 2019
This paper is about the incremental computation of control sequences for complex discrete event s... more This paper is about the incremental computation of control sequences for complex discrete event systems (DES). Transition-timed Petri nets (T-TPNs) that behave under earliest firing policy are used to model hybrid FMS that has some operations with total precedence constraints and other operations with full routing flexibility. The objective is to find a control sequence from an initial state to a reference one in minimal time. For that, a cost function is proposed and used with a new variant of beam search method that selectively explores the PN state space.
IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society
2018 IEEE 23rd International Conference on Emerging Technologies and Factory Automation (ETFA)
Journal of Control, Automation and Electrical Systems, Mar 3, 2021
This paper is about scheduling problems for a class of flexible manufacturing systems (FMS) that ... more This paper is about scheduling problems for a class of flexible manufacturing systems (FMS) that have some operations with total precedence constraints and other operations with full routing flexibility (namely hybrid FMS). The objective is to find a control sequence from an initial state to a reference one in minimal time. For that, a systematic multi-level formalism is introduced to model the hybrid FMS based on the hierarchical structuration of the operations. Transition-timed Petri nets (T-TPN) that behave under earliest firing policy are used for that purpose. Then a new cost function is introduced to estimate the residual time to the reference. This estimation is proved to be a lower bound of the true duration. A modified Beam Search algorithm is proposed that uses the cost function to selectively explore the Petri net (PN) state space. Computational experiments illustrate the efficiency of the approach in comparison with other existing methods.
Journal of Intelligent Manufacturing, Aug 25, 2021
Proceedings of the 2023 10th International Conference on Industrial Engineering and Applications
2022 8th International Conference on Control, Decision and Information Technologies (CoDIT)
Cette thèse concerne les problèmes d'ordonnancement pour une classe de systèmes manufacturier... more Cette thèse concerne les problèmes d'ordonnancement pour une classe de systèmes manufacturiers flexibles (FMS) en environnement incertain. Les systèmes considérés répondent aux exigences de l’industrie 4.0 qui requièrent des organisations plus agiles permettant de proposer des produits personnalisés. Plus précisément, les systèmes proposés dans ce travail sont appelés FMS hybrides et traitent les opérations avec des contraintes de précédence partielles entre les opérations. La première contribution est une approche systématique de modélisation des FMS hybrides avec les réseaux de Petri temporisés sur les transitions (T-TPN) et un formalisme multi-niveaux basé sur la structuration hiérarchique des opérations. La deuxième contribution concerne la recherche d’ordonnancements pour les FMS hybrides. Nous utilisons la recherche en faisceau et proposons une fonction coût basée sur la modélisation multiniveaux. Nous proposons également une nouvelle variante de la recherche en faisceau, ...
2019 18th European Control Conference (ECC), 2019
This paper is about the incremental computation of control sequences for complex discrete event s... more This paper is about the incremental computation of control sequences for complex discrete event systems (DES). Transition-timed Petri nets (T-TPNs) that behave under earliest firing policy are used to model hybrid FMS that has some operations with total precedence constraints and other operations with full routing flexibility. The objective is to find a control sequence from an initial state to a reference one in minimal time. For that, a cost function is proposed and used with a new variant of beam search method that selectively explores the PN state space.
IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society
2018 IEEE 23rd International Conference on Emerging Technologies and Factory Automation (ETFA)