Running Train Scheduling Based On Petri Nets

Train traffic dispatch is one of the key parts of the railway transportation system, which is related to the trains safty and punctual. On the basis of the research on petri theory, petri net theory and analysis method are introduced into train traffic control, and the concept of the hybrid colored petri net(HCPN)is also presented in this paper. The main content of this paper is presented as follows:1) The research background of the train traffic control problem is outlined briefly, through comparing the research methods of home and abroad, the petri net theory and analysis method are used in the problem.2) The basic theory and the modeling method of petri net are introduced, such as the definition of the ordinary petri net, the operation rule, the properties of petri net, and the definition of the ordinary colored petri net.3) Through analyzing the train operation process, it is indicated that the process is a hybrid system. On the basis of the ordinary colored petri net, the formal definition of the HCPN is presented, which includes two kinds of places, the discrete places and the continuous places. The train traffic control model is built, which based on the HCPN, by regarding trains as tokens in the continuous places and resource equipments as tokens in the discrete places. The model can describe the control constraints which must be satisfied during trains operation process and the train dispatching activity and avoids designing of the monitor used in other paper. The train traffic control model is analyzed theoretically using petri net analysis method. It is indicated that the model has some discrete properties such as structural boundedness, partial conservativeness, liveness and so on, and the function of the dispatching place in this model is also pointed out. Therefore, the correctness of the model was guaranteed in theory. Through the analysis of the model, a conclusion had obtained that the train traffic control problem is an optimum control problem in essential.4) The model is simulated by CPN Tools, the Simulation results can validate the correctness of control logic relationships. The properties of the model is analyzed and validated by state space report, it is indicated that the prediction model is feasible.