International Conference on Economic Engineering and Manufacturing Systems Braov, 25 – 26 October 2007 , Vol. 8, nr. 3a(21a), November, 2007 249 PETRI-NET BASED APPROACHES TO FLEXIBLE MANUFACTURING SYSTEMS Mihaela - Elisabeta CIORTEA * , Liviu MORAR ** , Adrian PISLA ** , Camelia VLAD ** * University “1 DECEMBRIE 1918” Alba Iulia, Romania ** Technical University of Cluj-Napoca, Romania Abstract: 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 in production systems. A generalized multi-productive machine module is defined, adapted to system feature, repeated and connected to compose the TPN models of production systems with different levels of routing and operation flexibility. Keywords: Petri nets, manufacturing systems, MATLAB 1. Introduction Petri net theory is developed twofold: - Formal Petri net theory – elaborates the means, methods and notions for the use of Petri nets, - The applicative theory of Petri nets – aims to use Petri nets for system modelling, system analysis and to obtain results. Petri net based distributed system modelling takes place at the state level: it determines the actions that take place in the system, the states that precede these states and the state in which the system will pass after the actions have taken place. By simulating the state model through the Petri nets, we obtain a description of the system’s behaviour. This paper presents a concrete step-by-step methodology using t-timed ordinary modular PNs for modelling, analysis, synthesis, performance evaluation and simulation of random topology dedicated production systems, viewed as surplus based systems, composed of workstations and buffers, where machines fail and are repaired randomly. For a random topology dedicated production system, whether single or multiple part type or cyclically scheduled, with finite or infinite capacity buffers, the following are accomplished: 1. Production system decomposition-analysis. - generic modules and generic PN modules that correspond to the one input buffer-one machine-one output buffer transfer chain module, two input buffers-one machine- one output buffer assembly module, one input buffer-one machine-two output buffers disassembly module and two parallel machines module, - generalized modules and generalized PN modules that correspond to the n TCi machines-(n TCi + 1) buffers transfer chain module, n Ai input buffers – one machine – one output buffer assembly module, one input buffer – one machine – n Di output buffers disassembly module and one input buffer – n Pi parallel machines – one output buffer module. 2. Production system composition-synthesis. - component connectivity, this is determined by places fusion at the respective module connecting points,