The Optimization And Coordination Theory Of Petri Nets And Its Applications

Petri Nets, as a formal modeling and analysis tool, not only has visual graphical descriptionability, but also easy to adapt profound mathematical method for properities analysis. It had beenwidely applied in discrete event systems, such as flexible manufacturing systems, transportationcontrol systems, computer networks, etc, and its theory has made a good effect. However, the Petrinets theory in system performance modeling, optimization and coordination still has many immatureaspects, which prevent it from applying to deeper and wider area in the event based dispatchingsystems. In this dissertation, the research works are carried out to resolve some important problemsof optimization and coordination theory based on Petri nets, and their applications in locomotivedispatching system of coal mine. The main works are summarized as follows:(1) As the beginning of studies, the dissertation interprets the limitations of the performanceevaluation studies by classical queue theory and stochastic Petri nets, and presents the performanceevaluation methods based on hierarchical colored Petri nets (HCPN) simulation, furthermore theconverting steps and rules from queue systems to HCPN models are given. By using the DataCollector kit in CPN Tools, the dynamic simulation data is collected, and then the performanceindices calculation formulas are defined. Based on the metioned above, several examples of classicalqueue system and queue system with vacations are analyzed, and the simulation results show that theperformance evaluation methods based on HCPN simulation are effective and correct.(2) According to the RT-circuit theory of the constructed resource allocation Petri net models,the deadlock and impending deadlock states are analyzed, and then the deadlock-free dispatchingconditions are studied under two correlated resources, the sufficient condition with the necessary andthe sufficient condition are presented and proved. Furthermore, based on deadlock-free dispatching,the maximal makings boundary setting algorithm is proposed, and the deadlock-free property ofdispatching under maximal marking boundary setting is proved. Then, a genetic optimizationalgorithm frame is constructed, and the coding method and algorithm procedures are elaborated indetail. Lastly, based on the mentioned above, the locomotive dispatching system of coal mine underthree control strategies is studied and simulated actually, the exprimental results show that thedeadlock-free optimization method based on Petri nets is feasible.(3) By extending the definitions of transitions (transition sets) fair relationships, the concepts offair relationship between transitions (or transition sets) and synchronic distance in hybrid Petri netsare defined, by using pruned IB evlution graph, the synchronic distance determination algorithm isfirst put forward. Then, the sufficient and the necessary conditions for fairness determination areproved, and the relationships among fairness, synchronic distance and the pruned IB evolution graphare certified. As for the coordination control problems occurring in the situations that differentdispatching objects or behaviors synchronize control, the design procedures of synchronizationcoordination controller are given, and some cases are exampled for interpretation for the proposedtheory.(4) As for the immature aspects of fault diagnosis algorithms in partially observed systems, thepartially oberseved system design method is considered, which satisfying fault diagnosis conditionsand has only some places can be observed, then the fault location table and monitoring placesdetermination (FLT&MPD) algorithm is constructed, whose correctness and solution existence areproved formally. In the meanwhile, it is pointed that the complexity of the proposed algorithm ispolynomial. Furthermore, the system operating state diagnosis (SOSD) algorithm is presented. Through the SOSD algorithm, the system’s state can be judged, and the occurred fault can belocated correctly. A partially observed system design is exampled for a complex flexiblemanufacture system, and a series of faults diagnosis conditions are listed, the example shows that theproposed partially observed system design method extends the existed studied results.(5) By applying the optimization and coordination theory of Petri nets studied in dissertation inthe locomotive dispatching system of coal mine, the performance modeling method is emphaticallyanalyzed firstly. Through actually simulation, the experimental results show that the proposedperformance evaluation method is effective. Secondly, according to the synchronization coordinationcontroller design procedures based on synchronic distance, the definitions of synchronizationcoordination controller in event based dispatching system are formulated, and exampled two kinds ofsynchronization coordination controller in locomotive dispatching system of coal mine, whichrealizes the coordination between locomotive transporting behavior and mining behavior, and thecoordination between different locomotive transport frequency to ensure fair property. Lastly, as fortwo typical faults, the fault detection model is constructed using HCPN, and each fault unambiguousdiagnosis condition is calculated by algorithm proposed, which can ensure the safety and reliabilityof locomotive dispatching system of coal mine.