An Approach for a Manufacturing System Based on Supervisory Control Theory and Colored Petri Nets (original) (raw)
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A Hybrid Control Architecture Applied to Flexible Manufacturing Systems
World Congress, 2008
The introduction of advanced information systems and machinery with communication capability and operational versatility provide the manufacturing systems with the capacity of material modification and transport, changes in material processing routes, different product insertion in the production line and plant layout reconfiguration. These characteristics give the production process great flexibility. Supervisory Control Theory (SCT) and Colored Petri Nets provide a formal tool for developing controllers for Discrete Event Systems, e.g., Flexible Manufacturing Systems (FMS). One of the problems for implementing this approach is the difficulty that the modeling of the subsystems and specifications represent in today's modern manufacturing systems. In Flexible Manufacturing Systems the transport mechanism is identified as the subsystem that provides these functionalities. This paper describes the modeling of the subsystems and specifications for a large Flexible Manufacturing System using a hybrid integrated framework.
Petri-Net Based Approaches to Flexible Manufacturing Systems
This paper describes the planning process in flexible manufacturing systems. Flexible manufacturing system consisting of machines, computers, robots and automated guided vehicle. The skeleton and the functionality of a Petri Net Toolbox, embedded in the MATLAB environment, are briefly presented, as offering a collection of instruments devoted to simulation, analysis and synthesis of discrete event systems. The integration with the MATLAB [1] philosophy responds to the general interest manifested by educators for enlarging the compatibility between the traditional background of Control Engineering applications and the novelty of discrete-event-systems scenarios. It explains a scheme of labelling and firing which makes modelling convenient for complex systems whose constraints are difficult to express only in terms of firing duration. The system manufacture choose is from the undertake S.C. APULUM S.A. Alba Iulia. Timed Petri nets are used to model operational and routing flexibility ...
1994
A PETRI-NET BASED METHODOLOGY FOR MODELING, SIMULATION, AND CONTROL OF FLEXIBLE MANUFACTURING SYSTEMS by Venkatesh Kurapati Global competition has made it necessary for manufacturers to introduce such advanced technologies as flexible and agile manufacturing, intelligent automation, and computer-integrated manufacturing. However, the application extent of these technologies varies from industry to industry and has met various degrees of success. One critical barrier leading to successful implementation of advanced manufacturing systems is the ever-increasing complexity in their modeling, analysis, simulation, and control. The purpose of this work is to introduce a set of Petri net-based tools and methods to address a variety of problems associated with the design and implementation of flexible manufacturing systems (FMSs). More specifically, this work proposes Petri nets as an integrated tool for modeling, simulation, and control of flexible manufacturing systems (FMSs). The contrib...
Petri nets and flexible manufacturing
Lecture Notes in Computer Science, 1990
The aim of this survey is to introduce Computer science/Petri nets specialists to the basic system level issues brought up by the development of Flexible Manufacturing and how Petri nets are used to aid the production engineers in their work. After some terminology concerning production engineering, the hierarchical decision and control level is briefly reviewed. Finally, the role and the presence of nets in CAE (Computer Aided Engineering) and in CAM (Computer Aided Manufacturing) for FMSs (Flexible Manufacturing Systems) are considered. From the design point of view, the use of nets have many advantages in modeling, qualitative analysis, performance evaluation and code generation. From the control of the plant perspective, scheduling on nets models, the coordination of the plant (global and partial) and the presence of nets in the local control level are discussed. Petri nets theory presents a relatively mature body, nevertheless efficient performance evaluation (even for P/T net models) and qualitative analysis of highlevel net models still requires important developments. The Babel-Tower-impression that the Petri net newcomer may have looking at the myriad of so-called high-level-nets formalisms may initially produce some kind of rejection. In any case, it is our opinion that Petri nets appears as a key formalism to describe, analyze and implement the control of FMSs. The merging of Petri nets and knowledge based techniques seems to be very promising to deal with large complex discrete event dynamic systems such as FMSs. Petri Nets and Flexible Manufaturing (rebuilt version January 24, 2005) Gentina, P. Muro, J.L. Villarroel, K. Voss and many other persons. 6 References. 6.1 References on general notions in manufacturing systems. BAL 69 Balas E., Machine sequencing via disjunctive graphs: an implicit enumeration algorithm, Oper. Res. 17 No 6. ERS 79 Erschler J., Fontan G., Roubellat F., Potentiels sur un graphe non conjonctif et analyse d'un problème d'ordonnancementà moyens limités, RAIRO, 13 No 4. ERS 86a J. Erschler, F. Roubellat, V. Thomas: Real-time Production Scheduling for Parts with Limit Times. TIMS/ORSA Joint National Meeting, Los Angeles, April. ERS 86b J. Erschler, P. Esquirol: Decision-aid in job-shop scheduling: a knowledge based approach. SIL 85 M. Silva: Las redes de Petri en la Automática y la Informática. Ed. AC, Madrid. SIL 87a M. Silva: Towards a synchrony theory for P/T nets. Concurrency and Nets (K. Voss et al., eds). Springer-Verlag, pp. 435-460. SIL 88 M. Silva, J.M. Colom: On the computation of structural synchronic invariants in P/T nets.
IEEE Transactions on Systems, Man, and Cybernetics, 1990
multiple types of places, multiple classes of tokens and multiple arcs is proposed. It is utilized for the hierarchical modeling of flexible manufacturing systems ensuring ( I priori that the extended Petri net system model obtained is live, bounded, consistent and error-free. The proposed methodology views the operation of the flexible manufacturing system as a process that is decomposed into operations with specified precedence relations. For each operation the required resources are identified and based on them, the overall system is decomposed into a set of finite subsystems. The operation of each subsystem is modeled as an event-graph representing a single resource activity cycle. The extended Petri net system model is synthesized from these component nets based on certain synthesis rules. A software package has been developed to simulate the execution of the obtained extended Petri net model.
Petri nets and manufacturing systems: An examples-driven tour
There exists ample literature on Petri nets and its potential in the modelling, analysis, synthesis and implementation of systems in the manufacturing applications domain (see for example ; moreover, in [65] an important bibliography is presented). This paper provides an examples-driven perspective. Nevertheless, not only complete examples from the application domain are considered. Manufacturing systems are frequently large systems, and conceptual complexity often appears because of some particular "local" constructions. The examples considered in this selected tour try to introduce in a progressive way some applied concepts and techniques. The starting point is an assembly cell, for which models concerning several phases of the design life-cycle are presented. Afterwards, some pull control and kanban management strategies are modelled. Then, two coloured models of production lines are presented. After that, a manufacturing system with two cells is modelled, and the difficulty of the practical analysis is shown. For very populated manufacturing systems or systems with high cadence, relaxation of discrete event models leads to hybrid and continuous approximations, an example of which will be introduced.
Using Petri net models at the coordination level for manufacturing systems control
Robotics and Computer-integrated Manufacturing, 1994
This paper focuses on the coordination of manufacturing systems. A software architecture for manufacturing systems control is presented. The architecture follows a hierarchical approach for control, ranging from real-time coordination to long-term scheduling, where the different layers share a common knowledge base. A knowledge representation schema for manufacturing systems is proposed. This schema integrates knowledge representation techniques based on frames and high-level Petri nets to describe plant behaviour, and it follows an object-based methodology. The coordination function is materialized by making the coordination model evolve; this is done by a centralized, concurrent and interpreted implementation of the underlying Petri net.
Modeling Framework for Automated Manufacturing Systems Based on Petri Nets and ISA Standards
Studies in Informatics and Control, 2013
This work presents a systematic methodology to model Automated Manufacturing Systems using Petri Nets. The modelling strategy consists in the definition and the interconnection of some generic Petri Net models applied to the discrete-event dynamic behaviour of the equipments and its procedures. It is based on the industrial standards ISA-88 and ISA-95, where the classification of equipment and the definition of their generic process tasks are suggested, separately of the product manufacturing recipes. The approach provides a formal and ordered methodology to study industrial automated systems where the equipment availability, storage limitations, sharing resources and logic precedence between process tasks appear in the Petri model. A complete case of study related to an automated cell is presented which includes a network of PLC's and industrial robots.
Petri Net Modeling of a Production System with Parallel Manufacturing Processes
Journal of Science and Arts
This paper presents the modelling and control of a flexible manufacturing system with integrated Industry 4.0 concepts using Petri nets. The flexible manufacturing system is composed of 7 workstations that ensure the assembly and disassembly of two types of products on two parallel production processes. The two parallel processes, in-line and in-cell production processes, ensure the assembly of the products and disassembly of the defects with a minimal number of stations. wo types of controls, local and centralized, are implemented in the control of production processes. The local control, based on the PLCs of each station, ensures the control of the assembly process at the workstation level. The centralized control ensures the obtaining of desired results at the level of interaction between the stations and also the implementation of the optimization algorithm results. To better understand and develop the control of the system a Petri net model was developed. Based on the propertie...