Research On Modeling Method Of Transportation Cyber-physical System

At present,there are three main theories of Cyber-Physical System（CPS）modeling:unified model theory,hybrid model theory,theory of data-driven modeling and extended model theory.However,these first three kinds of modeling theories have poor compatibility and high implementation complexity for the representation of continuous physical system and discrete information system involved in CPS.For the scene in the T-CPS,it has both continuous processes and discrete operations.Therefore,on the basis of the extended model theory,this thesis expands and improves the Petri Net to enhance the expressive ability of the model,which is used for the modeling and analysis of the T-CPS.The method is used to fuse the continuous process of physical perception in the T-CPS with the discrete model of the information system.It can not only analyze the impact of physical events on the information system,but also reflect the phenomenon that the information system changes the physical world through calculation,control,and execution.The main research contents of this thesis are as follows:（1）Clarified the characteristics and modeling challenges of CPS,summarize multiple mainstream methods of CPS modeling,and also clarify the difficulties of combining information systems with physical systems.Therefore,this thesis select Petri nets as formal modeling method.（2）Petri net is a mathematical representation of discrete parallel system.It has both mathematical expression and graphical expression.In order to make Petri net better describe discrete events in CPS and compatible with continuous attributes,we propose Hierarchy Colored Timed Petri Net（HCTPN）,the hierarchical model,the color sets and the timed attribute are introduced on the basis of the Petri net.By using HCTPN to model the workflow of the Vehicles with CPS combined with the Forward Collision Warning System（FCWS）and also the modeling’s rationality is analyzed.Furthermore,we also use HCTPN to analyze the CPS intelligent community parking system.Then,we proposed three models of intelligent decision-making management and give the model diagram of CPS controller and the parking lot area.We carry out the model feasibility analysis at last.Finally,we analyzes the BRT parking case.Firstly,we model the BRT vehicle and road unit.On this basis,the system modeling is carried out in combination with the passenger getting on and off events.And we improve the modeling according to the analysis of reachable marking graph.（3）In the verification experiment,firstly,we analyze the properties of HCTPN to ensure that it meets the properties of the prototype Petri net.We verify the three above examples separately: We describe the CPS behavior as an automaton network with clock and data variables.For the meeting of the real-time performance of CPS,a clock limit is arranged on the state of each state machine to check the real-time performance of CPS.We use UPPAAL to test the deadlock,feasibility and accessibility of the Vehicles with CPS combined with the FCWS model.For the CPS intelligent parking system,simulation experiments are carried out for the three proposed intelligent decision-making models.The results show that the proposed model can solve the conflict problem within a suitable delay range.Finally,for example 3,the experiment shows that the proposed model can realize the safety problem of passengers getting on and off the bus.The experimental results show that the HCTPN can be effectively applied to the modeling and analysis of T-CPS.