Study On Pinning Synchronization Of Complex Networks For Urban Expressway Integrating Adjacent Intersections

As an important part of road network in many large or mega cities,urban expressway has the advantages of fast speed and large capacity.However,the increasing traffic pressure in some cities has made expressways even more congested,especially during periods of high traffic demand such as commuting time.Multi-ramp coordinated control is an effective method of urban expressway management.This is because the distance between adjacent ramps of expressway is short,the effect of mainline speed limit and flow regulation of single ramp are limited.However,the existing multi-ramp coordinated control methods are less involved in the optimization and determination of the range for control signal,and less concerned with the situation that "no signal light is set on ramps and flow regulation is achieved only through the use of signal lights at adjacent intersections".In addition,complex network synchronization and its pinning control are less used.Based on this,complex network theory is used as the theoretical basis,and Cell Transmission Model(CTM)is adopt to establish a node coupling model of expressway integrating adjacent intersections.The complex network synchronization controller of expressway is designed,and the conditions of synchronization for expressway is calculated with the goal of suppressing congestion.Taking the section of "Binyue Bridge of Hongqi South Road-Haijin Bridge at the junction of Heiniucheng Ave and Kunlun Road" in counterclockwise direction of the south half ring of expressway in Tianjin city as the experimental object,the coordinated control of the expressway under congestion is verified.The specific contents are as follows:(1)The complex network characteristics of expressway are analyzed.Firstly,each component of urban expressway is analyzed to understand the structure of expressway system.Secondly,the traffic flow characteristics of expressway are analyzed to lay a theoretical foundation for the subsequent model establishment from three aspects:parameters relationship of traffic flow,congestion propagation characteristics,and the relationship of vehicle diversion,confluence and route choice.Finally,the expressway is analyzed from three aspects: topological structure,statistical characteristics of complex network and destructiveness of network,which provides a theoretical basis for the establishment of node coupling model of expressway.(2)A node coupling model of expressway integrating adjacent intersections is established.Firstly,the modified CTM of mainline,on-ramp and adjacent intersection,and off-ramp and adjacent intersection are built,respectively.Secondly,the rules for dividing cell and node of expressway are determined,which lays a foundation for the establishment of node coupling model of expressway.Finally,based on the coupling model of complex network and cell transmission relationship between nodes,the node coupling model of expressway integrating adjacent intersections is established.(3)Expressway coordination controller based on complex network synchronization is designed.A pinning control strategy for multiple on-ramp and adjacent intersections is proposed,where the signal timings of adjacent intersections are used as the decision variables.Based on the theory of pinning synchronization of complex network,the control algorithm is designed,the system stability condition is derived,the control node and optimization parameters are obtained,and the signal timing scheme is optimized.The signal timing scheme is adjusted according to the off-ramp queue length and the traffic state of off-ramp and adjacent intersection coordination control module to prevent the off-ramp queue spillover into expressway.(4)The simulation experiment is performed and analyzed.The section of "Binyue Bridge of Hongqi South Road-Haijin Bridge at the junction of Heiniucheng Ave and Kunlun Road" in counterclockwise direction of the south half ring expressway in Tianjin city is used as the experimental object.ALINEA algorithm,CORDIN strategy,global control,no multi-on-ramp coordinated control and the proposed method of pinning control are set up for comparison to verify the effectiveness of the proposed method.The results indicate that the traffic jam phenomenon can be suppressed,off-ramp congestion can be mitigated,and the operational efficiency can be enhanced at minimal control cost.