Finding Clusters in Petri Nets. An approach based on GPenSIM

Graph theory provides some methods for finding clusters in networks. Clusters reflect the invisible grouping of the elements in a network. This paper presents a new method for finding clusters in networks. In this method, the user can adjust a parameter to change the number of clusters. This method is newly added to the simulator General-purpose Petri Net Simulator (GPenSIM) as a function for network analysis. With this GPenSIM function, in addition to the usual performance analysis of a discrete-event system via a Petri net model, supplementary information about the grouping of the elements can also be found. Finding clusters in discrete-event systems provides valuable information such as the ideal location of the elements in a manufacturing network. This paper also presents an application example on a flexible manufacturing system

Risk Assessment in a Parallel Production System with the Use of FMEA Method and Linguistic Variables

Part 5: Industrial Management and Other ApplicationsInternational audienceRisk is a natural and common phenomenon in enterprises. Elimination of risk is impossible, because it affects every decision. In order to manage a company effectively, the risk level should be taken into account at the stage of production planning and manufacturing process control. The paper describes a method for analyzing and assessing the risk in a parallel production system. Under this method it was proposed to use Failure Mode and Effects Analysis (FMEA) in the classic method for assessing the risk in a production system with a parallel structure. Such a combination allows determining the level of risk in a system without laborious evaluation of the amount of losses caused by the occurrence of risk factors in individual elements of the system

Multi-assortment production flow synchronization. Multiscale modelling approach

Increasing competition strongly influence a company that is looking for the efficient method of production control. Companies expand their production flexibility and control method in the whole value chain. In this paper, authors propose a new description of the production inspired by the multiscale modelling. In particular, the idea based on the modelling of concurrent cyclic processes and the ability to use this approach in complex production systems is presented. This paper also discusses modelling and simulation of multiscale production flows using the Activity-Oriented Petri Nets

Modular distributed models of production systems: a Petri nets based approach

Modeling and simulation are key performance analysis and control techniques to optimize decision-making as well as design and operate complex production systems. They are also indicated as one of the technological pillars of modern industry and IT solutions supporting the implementation of the roadmap toward Industry 4.0 in the areas of digital transformation and automation. In the context of the required rapid transformation of today’s enterprises, it becomes extremely important to look for solutions that allow the use of the existing infrastructure, information, and energy, so as to minimize the negative impact of new technologies and the transformation process itself on the environment. The article presents an approach to modeling large and complex production systems with the use of distributed Petri net models allowing the use of the possessed IT infrastructure as consistent with the idea of sustainable development in the activities of enterprises. This eliminates two major problems that render traditional models unusable. The first is related to the difficulties in analyzing and verifying models of enormous size and infinite space of states. The second is related to the required computing power, if such analyzes are to be performed on one computing unit, which would force the producers to replace the IT infrastructure. For this purpose, modular Petri nets are introduced. Other benefits of modularization, such as smaller components that can be independently analyzed, are also presented in the paper. The proposed modular Petri net has been implemented in the proprietary GPenSIM software. The paper is complemented by a practical example of industrial modeling of production systems with automated guided vehicles (AGVs) using the Modular Model with Intelligent Petri Modules

Multi-assortment production flow synchronization. Multiscale modelling approach

Increasing competition strongly influence a company that is looking for the efficient method of production control. Companies expand their production flexibility and control method in the whole value chain. In this paper, authors propose a new description of the production inspired by the multiscale modelling. In particular, the idea based on the modelling of concurrent cyclic processes and the ability to use this approach in complex production systems is presented. This paper also discusses modelling and simulation of multiscale production flows using the Activity-Oriented Petri Nets

Performance Evaluation of Discrete Event Systems with GPenSIM

Petri nets are a useful tool for the modeling and performance evaluation of discrete event systems. Literature reveals that the Petri Net models of real-world discrete event systems are most frequently event graphs (a subclass of Petri nets). Literature also reveals that there are some simple methods for the performance evaluation of event graphs. The general-purpose Petri Net simulator (GPenSIM) is a new simulator that runs on the MATLAB platform. GPenSIM provides a Petri net language, with which Petri net classes and extensions can be developed. GPenSIM also provides functions for performance analysis. Since real-world discrete event systems usually possess a large number of resources, the Petri net models of these systems tend to become huge. Activity-Oriented Petri Nets (AOPN) is an approach that reduces the size of the Petri nets. In addition to the simulator functions, GPenSIM also realizes the AOPN approach on the MATLAB platform. Thus, AOPN is an integral part of GPenSIM. As a running example, a flexible manufacturing system is firstly modeled as an event graph, and then the size of the model is reduced with the AOPN approach. The advantages of GPenSIM and AOPN are discussed in this paper

The Method of Production Scheduling with Uncertainties Using the Ants Colony Optimisation

Production and maintenance tasks apply for access to the same resources. Maintenance-related machine downtime reduces productivity, but the costs incurred due to unplanned machine failures often outweigh the costs associated with predictive maintenance. Costs incurred due to unplanned machine failure include corrective maintenance, reworks, delays in deliveries, breaks in the work of employees and machines. Therefore, scheduling of production and maintenance tasks should be considered jointly. The problem of generating a predictive schedule with given constrains is considered. The objective of the paper is to develop a scheduling method that reflects the operation of the production system and nature of disturbances. The original value of the paper is the development of the method of a basic schedule generation with the application of the Ant Colony Optimisation. A predictive schedule is built by planning the technical inspection of the machine at time of the predicted failure-free time. The numerical simulations are performed for job/flow shop systems

An attempt of CNC machining cycle’s application as a tool of the design feature library elaboration

This paper presents a novel approach to a problem of the design feature library elaboration. As a tool of the design feature library development CNC machining cycles were proposed. Because of the great number of commercially available CNC machine controllers, with different CNC machining cycles definitions, it was necessary to make a decision about a research methodological framework, it is the selected CNC machine controller. Taking into account the criterion of popularity as the research framework the selected group of Sinumerik CNC machine controllers was chosen. Presented in the paper idea of the feature library development is based on an assumption saying that it is possible to find a relationship between a particular CNC machining cycle and the simple design feature or even compound design features. Identified, thanks to this assumption, set of the design features could be the base for elaboration of the design feature library. This solution, it is the feature library next gave opportunity for elaboration of the feature based design modelling module (FBDMM) working in the SIEMENS NX system environment. Hence, the FBDMM module can support both a designer and CNC machine programmer which is possible due to received in the module modelling paradigm. In FBDMM module the removal feature based modelling technique is received

An attempt of CNC machining cycle’s application as a tool of the design feature library elaboration

This paper presents a novel approach to a problem of the design feature library elaboration. As a tool of the design feature library development CNC machining cycles were proposed. Because of the great number of commercially available CNC machine controllers, with different CNC machining cycles definitions, it was necessary to make a decision about a research methodological framework, it is the selected CNC machine controller. Taking into account the criterion of popularity as the research framework the selected group of Sinumerik CNC machine controllers was chosen. Presented in the paper idea of the feature library development is based on an assumption saying that it is possible to find a relationship between a particular CNC machining cycle and the simple design feature or even compound design features. Identified, thanks to this assumption, set of the design features could be the base for elaboration of the design feature library. This solution, it is the feature library next gave opportunity for elaboration of the feature based design modelling module (FBDMM) working in the SIEMENS NX system environment. Hence, the FBDMM module can support both a designer and CNC machine programmer which is possible due to received in the module modelling paradigm. In FBDMM module the removal feature based modelling technique is received