Modelling Manufacturing Systems in a Dioid Framework

The paper is a partial synthesis of the work that a team within the Faculty of Managerial and Technological Engineering has in the field of modeling and simulation of systems with Petri nets. The paper deals with three issues. The first part is Modeling and simulation of manufacturing systems with timed Petri nets. The first part presents the way in which the performances of some manufacturing systems are evaluated using timed Petri nets. The first example is a manufacturing system specific to the textile industry. The system has three production lines. In this case, the modeling with timed Petri nets allows the analysis of the operation of the flow lines and highlights the bottleneck. Another modeled manufacturing system is specific to a series production, more precisely it refers to the manufacture of gas cookers within a company from Oradea. The model with Petri nets also describes the supply sequences of the stocks of parts and subassemblies. The next modeled system is an automated manufacturing system for the packaging of detergents. The complexity of the Detergent Packing System and the high level of automation, require the use of efficient modeling and simulation methods to verify the validity of the solutions adopted. In this chapter is present the model of a robotic welding cell. The second part of the paper, the transition from timed Petri nets to hierarchical colored Petri nets, shows how Petri nets were developed for a robotic cell for metallographic analysis. The third part is dedicated to modeling with colored Petri nets timed with complex colors of the flexible manufacturing cell A007 within the Department of Industrial Engineering.

Modeling and analysis of discrete-event dynamic systems representing manufacturing processes are considered. The manufacturing processes considered represent the repetitive production of a given number of products by means of a fixed set of machines. It is necessary to introduce a certain number of simplifying assumptions to make the system representable by timed event graphs, a special class of Petri nets, for which tools capable of providing an analytical performance evaluation exist. In this framework, some analysis and optimization problems can be considered. >

This paper presents an investigation of three simulation packages: VS7, SIMAN/CINEMA IV, and SIMFACTORY II.5. These packages were investigated with regard to their capabilities of modeling problems related to a Manufacturing Systems Design (MSD) Framework, which involves different levels of detail. These levels are the Conceptual Modeling level and the Detailed Design level. The investigation is based on a case study which relates to manufacturing systems. The main objective of this investigation was to examine the existing manufacturing simulation packages and their abilities to offer variable detail modeling. The paper also suggests that it may not be possible to have an existing simulation environment that offers flexible facilities for variable detail modeling of manufacturing systems. The paper presents a method of data arrangement that may be able to help existing simulation packages cope with problems of detail variability.

We deal with timed event graphs whose holding times associated with places are variable. Defining a first-in-first-out functioning rule, we show that such graphs can be linearly described in (max,+) algebra. Moreover, this linear representation allows extending the just-in-time control synthesis existing for timed event graphs with constant holding times. An example is proposed in order to illustrate how the approach can be applied as a just-in-time strategy for production lines.

The manufacturing field is an area where the application of simulation is an essential tool for validating methods and architectures before applying them on the factory floor and the warehouse control. Multiagent system technology has demonstrated its utility in manufacturing system modelling and implementation. Agenthood features such as proactivity, reactivity, sociability and trust may also be useful for associating them with the specific simulation needs of the new manufacturing and warehouse management requirements. In this article, we present an agent-supported simulation tool for an intelligent manufacturing system and its influence with the management of the warehouse applied to a metal-mechanic manufacturing enterprise. The main goal is to provide a flexible simulation tool that can be adapted to solve the new manufacturing requirements and optimise and validate methods of management of material in warehouses that appear in real environments. Thus, the benefits of the multiagent theory application for the simulation of intelligent manufacturing and warehouse management system allows the experts of manufacturing domains to optimise the resource usage, control of inventory, providers and to have enough data to make decisions that influence the production level are presented.

The objective of the present research is to develop a formal modeling method, aimed at realising concurrent development and integration of various manufacturing system models. An object-oriented model repository of the manufacturing system is discussed to establish a systematic and logical criteria for classifying the manufacturing system models from various viewpoints. Contents and structures of manufacturing system models are discussed from the viewpoint of the concurrent and hierarchical production planning problems, and model components and their relations to be stored in the model repository are proposed. A prototype of a model repository is developed and applied to the production planning problems.KeywordsModelingmanufacturing systemmodel repositoryobject-oriented approachproduction planning

Shortening product lifecycles and small lot sizes require manufacturing systems to adapt increasingly fast. Many existing machine tools, handling and logistics systems are already generic and not bound to a specific product a-priori. Yet this flexibility and reconfigurability on the asset level is lost in automated systems that are limited to executing a small set of predefined actions in a fixed sequence. The SkillPro <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> project aims to develop a holistic service-oriented framework for modelling and orchestration of modern adaptable manufacturing systems. The core concept is a unified abstraction for manufacturing tasks: skills provided by the available assets and the requirements of the different production steps. The skill-based system model enables the transition from generic high-level descriptions to low-level formats that can be directly executed. Self-describing assets can be added, changed and removed at runtime, taking into account technical and economic conditions to best achieve the manufacturing goals.

During the last few decades, significant progress has been made in solving large-scale finite-dimensional and semi-infinite linear programming problems. In contrast, little progress has been made in solving linear programs in infinite-dimensional spaces despite their importance as models in manufacturing and communication systems. Inspired by the research on separated continuous linear programs, we propose a new class of continuous linear programming problems that has a variety of important applications in communications, manufacturing, and urban traffic control. This class of continuous linear programs contains the separated continuous linear programs as a subclass. Using ideas from quadratic programming, we propose an efficient algorithm for solving large-scale problems in this new class under mild assumptions on the form of the problem data. We prove algorithmically the absence of a duality gap for this class of problems without any boundedness assumptions on the solution set. We show this class of problems admits piecewise constant optimal control when the optimal solution exists. We give conditions for the existence of an optimal solution. We also report computational results which illustrate that the new algorithm is effective in solving large-scale realistic problems (with several hundred continuous variables) arising in manufacturing systems.

An intelligent reconfigurability model based on multi-agent theory was proposed in this paper to improve feasibility of automotive manufacturing system. Each production management department in automobile manufacturing enterprises was designed as an independent agent. The practicability and rationality of the manufacturing system model was simulated as communication and interactive between different agents in this multi-agent system through JAFMAS. The application of multi-agent model in the design of automobile manufacturing system can promote the reconfigurability and intelligent level of the system.

In this paper we present an approach for modelling and analyzing flexible manufacturing systems (FMSs) using Petri nets. In this approach, we first build a Petri net model (PNM) of the given FMS in a bottom-up fashion and then analyze important qualitative aspects of FMS behaviour such as existence/absence of deadlocks and buffer overflows. The basis for our approach is a theorem we state and prove for computing the invariants of the union of a finite number of Petri nets when the invariants of the individual nets are known. We illustrate our approach using two typical manufacturing systems: an automated transfer line and a simple FMS.

Chapter 9 - The role of big data analytics in the context of modeling design and operation of manufacturing systems

Layout planning and analysis of a Flexible Manufacturing System based on 3D Simulation and Virtual Reality

This paper presents the design, generation and implementation of low cost control system for a manufacturing cell. The modeling and control of manufacturing systems using supervisory control theory (SCT) is discussed. Using the technique of SCT, controllers can be built according to operational specifications. A structure control implemented in low-cost physical platforms is presented. According to the level of control, micro-controllers or small-size PLC are used. A communication interface is proposed to establish rules of sending and receiving of events among different hardware. In order to demonstrate the usefulness of this approach, an educational testbed is used to simulate an automated manufacturing system.

Modern manufacturing systems consist of a sequence of robotic systems, such as robotic cells, which are widely used in the industry. As they become commonplace and play important roles in modern industrial production, efficient modelling and use of robotic cells become a necessity. Robotization brings many measurable benefits. It enables effective utilization of both human resources and the possessed machine park and thus contributing to the improvement of product quality and efficiency. Industrial robots not only increase the growth of productivity, by replacing man in monotonous works, requiring enormous, not achievable for human precision but above all ensure the accuracy and repeatability of the product quality. Appropriate design and modelling of robotic manufacturing systems are crucial in the efficient integration of work cell components and proper maintenance of robotic production systems. Therefore, new solutions for programming environments in industrial applications are sought which not only allow reprogramming of industrial robots but also enable the virtual design of new production lines, which in turn allows the faster introduction of higher quality products. This article presents the modelling and programming of robotic work cells in the Siemens Process Simulate environment.

Modelling and control of manufacturing systems using fuzzy petri nets