Estudo e implementação de técnicas de controle de sistemas a eventos discretos em CLP: aplicação em um sistema flexível de manufatura didático

Abstract

The production systems seek efficiency and reduction of costs to improve competitiveness in the market. In this way, automation exerts a fundamental role in the processes through coordination of the subsystems, in order that the individual operation and the overall operation of the system is guaranteed. A set of equipment that perform various activities and transform raw materials into products can be called a manufacturing system. A manufacturing system considered a flexible manufacturing system (FMS) when it presents product flexibility, production routes and capacity of a machine to perform different jobs.The FMS demands speed in development and change in control logic. Usually, the control logic is implemented in a programmable logic controller (PLC) based on the experience of the programmer and empirically. However, there are formal methods to implement controllogic in a PLC as Supervisory Control Theory (SCT) based on Automata and Petri Nets via Place Invariants. The structure of SCT has a plant that reflects the behavior physically possible of the system and a supervisor that performs a restrictive control action on the plant in a way to confine its behavior to that corresponding a given specification. The Languages and Automata Theory is the basis for modeling the plant and control specifications for the synthesis of supervisors that are obtained by Local Modular Control. The Petri Net (PN) is the basis for the Place Invariants that synthesize a supervisor able to restrict the operations of the plant modeled as a PN according to security restrictions. This work proposes the study and evaluation of three methods of implementation in a PLC of SCT based on Automata and one implementation methodology in a PLC of SCT based on Petri Nets via Place Invariants with the objective of practical implementation and automation of a flexible manufacturing system didactic built in the Laboratório de Análise e Controle de Sistemas a Eventos Discretos (LACSED) at UFMG. A comparative analysis between the four methods is presented and it is not intended to indicate the best methodology, but establish the advantages and disadvantages of each method of implementation in the PLC to promote knowledge and dissemination of the application of these methodologies.