Transportation Cyber Physical System Modeling And Simulation Based On Modelica

With the traffic problem becoming more and more serious, It is necessary to cognize the traffic phenomenon using a scientific approach and develop an advanced technology to support the transportation systems in order to relieve the traffic congestion and reduce environment pollution. So the development of the Intelligent Transportation System research is becoming more and more important. The appearance of Cyber Physical System(Cyber Physical System, CPS) provides an effective way to solve the traffic system of nonlinear, strong coupling and pan space-time issue. The Transportation Cyber Physical System(Transportation Cyber Physical System, T-CPS) apply the CPS concept to traffic field. Because of its complex structure and various disciplines and technologies, the current study has focused on the basic architecture of the system and the interpretation of the corresponding module features and technologies. The system modeling and simulation for T-CPS implementation is one of the important basic technology of transportation cyber physical system. This paper focuses on the modeling and simulation of transportation cyber physical system, the main research contents are as follows.First of all, we put forward an architecture including object layer, sensing layer, calculation of layer,control layer, execution and service layer and communication layer using the interaction and the feedback characteristics between the information world and the physical world in T-CPS system. We interpret the corresponding level functionality, with the former difference is that we believe that the communication layer is between the transmission of information throughout the various functional levels. This paper also introduces the basic knowledge to study to be involved, including the Modelica language, OpenModelica simulation platform and traffic flow theory.Next, the information flow based transmission direction in T-CPS basic architecture is proposed and the system above, we make a simple treatment of abstraction and some extent to every physical entity in the system. The library ensures the completeness of a model and gives the model of interface specification at the same time. The whole model library includes road segmentation module, segment connection module, detection device, controller, actuator and related supporting tool library. The model has general significance. We choose one of the modules can quickly build an actual urban road network information physical system.Thirdly,we studied the design of the signal lamp in the library. The controller is the core part of the system and mainly in charge of real-time data input to process and generate the control decision. The library includes two kinds of controller applied to the ramp entrance and intersection. The timing controller for traffic signal control strategy is commonly used in practice. Emptying switching control regards the physical transmission layer traffic flow in the road as switching service system and obtain signal lamp period through the control stability mode. The ALINEA controller adjusts its real-time signal timing based on the following travel traffic state. In the whole process of control, we can view real-time traffic flow changes on each section at any time through the simulation results.Finally, for a practical system contains four intersections, we apply the library to be model simulation and analysis the results.The thesis finally summarizes the research work, and proposed the further problems which we need to research.