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1、The synthesis and PLC implementation of hybrid modular supervisorsfor real time control of an experimental manufacturing systemGkhan Gelen a, , Murat Uzam ba Department of Mechatronics Engineering, Gaziosmanpa s a University, Tokat, Turkeyb Department of Electrical and Electronics Engineering, Melik
2、 s ah University, Kayseri, Turkeya r t i c l e i n f o a b s t r a c tArticle history:Received 7 May 2013Received in revised form 2 January 2014Accepted 28 April 2014Available online 8 June 2014Keywords:Discrete event systems Supervisory control theory Petri netsHybrid modular supervisorPLCLadder lo
3、gic diagramIn this paper, synthesis and PLC based implementation of hybrid modular supervisors for real time supervisory control of an experimental manufacturing system are proposed. The hybrid approach cou- ples Ramadge Wonham (RW) supervisors in the form of automata to uncontrolled PN models throu
4、gh inhibitor arcs. The RW supervisors can be obtained in monolithic or modular forms. In the monolithic case, there is only a single supervisor that has complex structure and huge number of states and events. The modularity of supervisors provides simple and small control structures compared to mono
5、lithic ones. Modular hybrid approach offers fewer states for the PLC implementation of the hybrid controller with less memory requirements. The applicability and effectiveness of the modular hybrid approach are demon- strated by the PLC based real-time control of an experimental manufacturing system
6、 for different cases. The obtained results show that modular supervisors require less memory space compared to monolithic counterparts. 2014 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.1. IntroductionA discrete event system (DES) is a dynamical system that
7、its evolution is not driven by time but by occurrence of events. Typical DESs include manufacturing systems, computer and communica- tion networks, logistic systems, and trafc control systems. As DESs become larger and more complex, more systematic methods are needed for the modeling and controlling
8、 of such large complex sys- tems. Supervisory control theory (SCT) based on formal languages and automata was introduced to extend control theory concepts for continuous system to DESs 13. In the SCT, a supervisor is computed for given plant and specications that describe the con- trolled behavior o
9、f plant 4. This computation process is named as supervisor synthesis. The main issue in the synthesis task is the state-space explosion problem 5,6. The number of states of the global system model grows exponentially with the number of com- ponents in the system. Addressing this problem, recent stud
10、ies on Corresponding author at: Department of Mechatronics Engineering, Faculty ofEngineering and Natural Science, Gaziosmanpa s a University, Tas lc iftlik Campus,60150 Tokat, Turkey. Tel.: +90 356 252 16 16; fax: +90 356 252 17 29.E-mail addresses: gokhan.gelengop.edu.tr , gokhan (G. Gelen).hierar
11、chical, decentralized and modular methods are proposed to reduce the complexity of supervisor synthesis tasks.In hierarchical architecture, supervisor synthesis is based on plant abstraction (high level model) which is supposed to be less complex than the original plant model (low level model) 79. I
12、n centralized supervision 1,2, the overall supervisory task is car- ried out by one single supervisor named as monolithic supervisor. The models of plant and specications are obtained by composition of components models. The decentralized and modular methods benet from this property. In decentralize
13、d and modular supervi- sion 10 12 , the specication can be decomposed according to the structure of the plant. A local supervisor is synthesized for each one of the specication parts. The local supervisors are run concurrently to carry out overall supervisory task. In modular supervision 13 , instea
14、d of designing a monolithic supervisor by using a single plant model and overall model of specication, local supervisors are syn- thesized by using local plant models and with related specication parts. The state explosion problem in the modeling and synthesis is reduced by using modular supervisory control methods.Alternatively, Petri net-based approaches to supervisory control design have been proposed. This is mainly because the state-space representation of PN as a vector addition system (whose states are integer-vectors, the P
