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The Hybrid Supervisory Control Of Discrete-event Systems

Posted on:2010-12-08Degree:DoctorType:Dissertation
Country:ChinaCandidate:F H LuFull Text:PDF
GTID:1118360302983897Subject:Control Science and Engineering
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Due to the rapid development of computer science and its extensive application in modern society, some researchers found a new type of dynamic system called discrete event systems (DES), which is different from continuous variable dynamic systems. The dominating characteristic of DES is that its evolution is not driven by time but by events. Essentially, DES is a manmade system. Typical DES include discrete manufacturing systems (especially FMS and CIMS), communication networks, traffic control systems, random service systems and computer operating systems, and so on.DES research mainly consists of system performance analysis and supervisory control theory. The main research tools of supervisory control of DES are automata/formal language and Petri net. These two tools both have its own advantages and disadvantages. For automata/formal language, it has clear conceptions, precise logic and intact theorem structural, but it is difficult to treat with physical events, concurrence and the state explosion problem. For Petri net, it has more powerful modeling and analysis ability, but it is lacking of uniform theory framework and difficul to guarantee the maximally permissiveness of the closed-loop systems. In this dissertation, we try to combine these two tools to give out the hybrid supervisory control of DES. Our efforts can be cataloged as follows:Firstly, the hybrid approach to supervisory control of DES based on constraints transformation is introduced. Our approach extends the hybrid approach which combines the PN and RW theory, and enlarges the application regions.Secondly, in order to have more efficient computation and powerful expression, we give the hybrid decentralized control of DES at the first time. The coordinator, which is an efficient tool to solve the blocking problem between the decentralized supervisors, is introduced into Petri net to keep the close-loop system to be non-blocking. Two methods, the experience and the structure way, are addressed to design the coordinator.Thirdly, the control flow net (CFN), which is a new graphical model that can help to do computationally efficient controller design for DES in the framework of automata, is introduced to work together with PN to get deallock-free control of DES. With fully exploiting the characteristics and advantages of CFN, it is used to detect the deadlock in the system, and give constraints to prevent the deadlock and obtain the maximally permissive deadlock-free closed-loop systems.Fouthly, we discuss the hierarchical control of DES in the view of formal language. And then we apply the theory into PN structure. Also we apply the hierarchical control in the scheduling control of DES. All this efforts help to complete the hybrid supervisory control architecture.Finally, we address the applications of the hybrid approach to supervisory control of DES. In theory side, a hybird approach to "Or-Logic" control of DES is introduced. In engineering side, the modeling and control of road-net system is discussed.To summarize in a word, we made a great effort on the development of the hybrid approach to supervisory control of DES, including centralized control, decentralized control and hierarchical control, and elementarily obtain a complete architecture of hybrid supervisory control of DES. In addition, the possibility of applying the obtained theory to engineering is discussed.
Keywords/Search Tags:Discrete Event Systems, Supervisory Control, Hybrid Approach, Decentralized Control, Hierarchical Control, Petri Net
PDF Full Text Request
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