Scheduling and discrete event control of flexible manufacturing systems based on Petri nets

A flexible manufacturing system (FMS) is a computerized production system that can simultaneously manufacture multiple types of products using various resources such as robots and multi-purpose machines. The central problems associated with design of flexible manufacturing systems are related to process planning, scheduling, coordination control, and monitoring. Many methods exist for scheduling and control of flexible manufacturing systems, although very few methods have addressed the complexity of whole FMS operations. This thesis presents a Petri net based method for deadlock-free scheduling and discrete event control of flexible manufacturing systems. A significant advantage of Petri net based methods is their powerful modeling capability. Petri nets can explicitly and concisely model the concurrent and asynchronous activities, multi-layer resource sharing, routing flexibility, limited buffers and precedence constraints in FMSs. Petri nets can also provide an explicit way for considering deadlock situations in FMSs, and thus facilitate significantly the design of a deadlock-free scheduling and control system. The contributions of this work are multifold. First, it develops a methodology for discrete event controller synthesis for flexible manufacturing systems in a timed Petri net framework. The resulting Petri nets have the desired qualitative properties of liveness, boundedness (safeness), and reversibility, which imply freedom from deadlock, no capacity overflow, and cyclic behavior, respectively. This precludes the costly mathematical analysis for these properties and reduces on-line computation overhead to avoid deadlocks. The performance and sensitivity of resulting Petri nets, thus corresponding control systems, are evaluated. Second, it introduces a hybrid heuristic search algorithm based on Petri nets for deadlock-free scheduling of flexible manufacturing systems. The issues such as deadlock, routing flexibility, multiple lot size, limited buffer size and material handling (loading/unloading) are explored. Third, it proposes a way to employ fuzzy dispatching rules in a Petri net framework for multi-criterion scheduling. Finally, it shows the effectiveness of the developed methods through several manufacturing system examples compared with benchmark dispatching rules, integer programming and Lagrangian relaxation approaches

A Review of Building Information Modeling and Simulation as Virtual Representations Under the Digital Twin Concept

Building Information Modeling (BIM) is a highly promising technique for achieving digitalization in the construction industry, widely used in modern construction projects for digitally representing facilities. Nevertheless, retains limitations in terms of representing construction operations. The digital twin concept may potentially overcome these limitations and initiate advanced digital transformation in the construction industry as it has revolutionized the product lifecycle management in the manufacturing industry. This research provides a critical review of applying digital twin in the construction industry. Altogether, 140 papers from related journals and databases were reviewed. The digital aspect of twinning consists of BIM and simulation modeling. These two techniques have been used to create virtual or digital representations of actual buildings and real-world construction processes. However, integrating and applying BIM and simulation modeling according to the digital twin concept remains to be fully studied. Comprehensive evaluations of BIM, simulation modeling, and digital twin will provide a well-defined framework for this research, to identify direction and potential for digital twin in the construction industry, thereby progressing to the next level of digitalization and improvement in construction management practice

Special Session on Industry 4.0

No abstract available

A Universal Framework for Lean Design and Control of Automated Material Handling Systems

Lean design and control of an automated material handling system is investigated in this study. A universal framework for modeling and analysis of different types of material handling mechanisms is introduced to obtain a minimum number of resources in a system design and fulfill a desired throughput. This framework is developed in a discrete event simulation environment and applied to a case study based on a real pallet system technology. The minimal design of the pallet system is realized by devising the system universal model

Modeling production configuration using nested colored object-oriented Petri-nets with changeable structures

Configuring production processes based on process platforms has been well recognized as an effective means for companies to provide product variety while maintaining mass production efficiency. The production processes of product families involve diverse variations in manufacturing and assembly processes resulted from a large variety of component parts and assemblies. This paper develops a multilevel system of nested colored object-oriented Petri nets with changeable structures to model the configuration of production processes. To capture the semantics associated with production configuration decisions, some unique modeling mechanisms are employed, including colored Petri nets, object-oriented Petri nets, changeable Petri net structures, and net nesting. The modeling formalism comprises resource nets, manufacturing nets, assembly nets and process nets. The paper demonstrates how these net definitions are applied to the specification of production process variants at different levels of abstraction. Also reported is a case study in an electronics company. The system model is further analyzed with focus on conflict prevention and deadlock detection

Basit bir makine - iki ürün sisteminin petri ağları kullanılarak modellenmesi, analizi ve simulasyonu

As in many engineering fields, the design of manufacturing systems can be carried out using models. Petri nets have been used extensively to model and analyze manufacturing systems. Petri Nets, as graphical and mathematical tools, provide a uniform environment for modeling, format analysis and design of discrete event systems. The modeling, simulation and analysis of simple one machine-two product systems using Petri nets will be presented in this paper. Behavioral and structural properties of the Petri net model will be considered in details. Then, the Petri net model of one machine-two product system will be simulated using a simulation program.Çoğu mühendislik alanlarında olduğu gibi imalat sistemlerinin tasarımı, modeller kullanılarak başarılabilir. Petri ağları imalat sistemlerinin modellenmesi ve analizinde yaygın olarak kullanılmaktadır. Petri ağları, şekilsel ve matematiksel araçlar olarak kesikli olay sistemlerinin modellenmesi, biçimsel analizi ve tasarımı için düzenli, iyi bir ortam sağlar. Bu makalede, basit bir makine-iki ürün sistemlerinin Petri ağları kullanılarak modellenmesi, simülasyonu ve analizi sunulacaktır. Petri Ağı modelinin davranışsal ve yapısal özellikleri ayrıntılı olarak incelenecektir. Daha sonra bir makine-iki ürün sisteminin Petri ağı modelinin bir simülasyon programı kullanılarak simülasyonu gerçekleştirilecektir

Modeling, Analysis and Simulation of Simple One Machine - Two Product System Using Petri Nets

Çoğu mühendislik alanlarında olduğu gibi imalat sistemlerinin tasarımı, modeller kullanılarak başarılabilir. Petri ağları imalat sistemlerinin modellenmesi ve analizinde yaygın olarak kullanılmaktadır. Petri ağları, şekilsel ve matematiksel araçlar olarak kesikli olay sistemlerinin modellenmesi, biçimsel analizi ve tasarımı için düzenli, iyi bir ortam sağlar. Bu makalede, basit bir makine-iki ürün sistemlerinin Petri ağları kullanılarak modellenmesi, simülasyonu ve analizi sunulacaktır. Petri Ağı modelinin davranışsal ve yapısal özellikleri ayrıntılı olarak incelenecektir. Daha sonra bir makine-iki ürün sisteminin Petri ağı modelinin bir simülasyon programı kullanılarak simülasyonu gerçekleştirilecektir.As in many engineering fields, the design of manufacturing systems can be carried out using models. Petri nets have been used extensively to model and analyze manufacturing systems. Petri Nets, as graphical and mathematical tools, provide a uniform environment for modeling, format analysis and design of discrete event systems. The modeling, simulation and analysis of simple one machine-two product systems using Petri nets will be presented in this paper. Behavioral and structural properties of the Petri net model will be considered in details. Then, the Petri net model of one machine-two product system will be simulated using a simulation program