Research On Control Model Of Urban Traffic Signal Based On The Extended Petri Net

As the rapid development of urbanization, the traffic system of our country becomes more and more complex, which bring much convenience for our life, at the same time, some kinds of traffic problems appear. Under the condition of existing roads, it is of great importance to set up a safe and reliable city traffic control model for mitigating the present traffic problems.The petri net has been used to model the city traffic system for a long time, with the complication of city traffic structure and multiplex of property, the origin Petri net appears some kinds of shortcomings, such as poor ability of expression, complex model and so on,which brings much difficulties to the further verification and analysis. In recent years, many scholars at home and abroad come up with a senior Petri net on the base of the origin Petri net,which could make the net system fold and strengthen the ability of describing, but the ability of expression and simulation have not been improved, especially it could not model the system which has priority or other special nature, so it is of great significance to expand the senior Petri net. The main contents of this thesis are as follows.1. A new kind of augmented Petri Net based on the archetypal Petri net has been proposed, which is called a colored Petri net with inhibitor arcs and enabling arcs. This is a new Petri net which vastly improve the modeling ability and enrich the theoretical knowledge of the Petri net. In the actual process of modeling, this augmented Petri net not only has strong simulation and modeling ability to make the model simple and clear, but also could describe the priority characteristics of the system.2. This new augmented Petri net has been applied on the city traffic signal control system,to model the dynamic traffic flow of the city crossroads, reflecting the dynamic change of the traffic stream, at the same time, it could detect and adjust the green-conflict phenomenon to ensure the safety of crossroads, building a high safety and high reliability single intersection city traffic signal control system.3. Based on the logical equivalence thought, the hardware description language Verilog has been used to simulate the augmented Petri net traffic control model which has inhibitor arcs and enabling arcs. The simulation results shows that it could reliably detect and adjust the green-conflict or other potential safety hazard, in addition, it could reflect the whole running state of system, accord with the expected effect.