Metodologia para implementação de controle supervisório modular local em controladores lógicos programáveis / Methodology for implementation of supervisory control local modular in programmable logic control

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

29/07/2011

RESUMO

Currently, manufacturing automation has assumed an increasingly important role within the industry and the problems of automated control systems have become increasingly complex. Thus, the traditional use of empirical methods heavily base on the experience of the programmer can lead to inappropriate or ineffective solutions. In this case, the Supervisory Control Theory (SCT) of Ramadge and Wonham (1989) cam be a suitable tool because it ensures the achievement of optimal control logic (minimally restrictive and nonblocking) and also that meets the specifications of control. This paper presents a methodology for implementation of SCT in Programmable Logic Controllers (PLCs). The modeling of the plant and the specification of control is done by automata and languages, and in order to exploit the modular nature of the plant and the specifications we use the local modular approach (QUEIROZ and CURY, 2000) for the synthesis of supervisors. The use of a formal methodology for implementing control system also allows to standardize in the development, testing and structure of the PLC code and obtain a free of errors solution and crashes, discarding the empirical methods. The methods of implementation of the TCS in PLC existing literature have the feature to limit the evolution of the system, often dealing with one event per PLC scan cycle. Also presented is a series of problems that can occur in the implementation of supervisors in control elements such as PLCs (FABIAN and HELLGREN, 1998). However, not all of these problems have solutions and for some of them are presented some properties that the modeling of the system must ensure in order to avoid such problems. This method treats all the uncontrollable events produced by the plant in just one PLC scan cycle. The also promotes the control of the plant at the end of cycle. The development of this methodology takes into account the possible problems when using the theory into practice. Thus providing solutions to the problems. In this case the solutions, Choice, stands out. It promotes the random generation of controllable events. One it is give priority to a particular event over another, it can cause the system to lock or be inoperative (MALIK, 2002). To facilitate the implementation of supervisory control structure in PLC, was created a computational tool for the automatic generation of control logic, based on the proposed methodology that converts the list generated by the software Discrete Event System (DES) in LADDER code. The validation of the results obtained with the tool generation was done through simulations for different problems of supervisory control.

ASSUNTO(S)

sistemas a eventos discretos controlador lógico programável célula flexível de manufatura automacao eletronica de processos eletricos e industriais discrete events systems flexible manufacturing cell programmable logic controller

ACESSO AO ARTIGO

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