Study On Coordinated Chaos Control Of Urban Expressway Based On Synchronization Of Complex Networks

As a backbone of the road networks of large cities and metropolitan,urban expressway has features such as fast speed and large flow.However,as a complex giant system with a wide range of nonlinear characteristics,fractals and chaotic phenomena exist widely in the traffic flow.If the traffic system is in the chaotic state,the system will develop toward the state of outer-ordered motion without management and control.If the chaos of traffic flow is identified in time and the chaos control signal is inputted within sufficient time,the wide-moving jam phenomenon can be suppressed because the system will shift from the chaotic state to ordered motion so as to ensure traffic safety avoid traffic congestion and achieve the purpose of improving traffic capacity.the existing traffic flow chaos recognition methods require a high number of samples,a large amount of computation,and a long time for real-time identification.It can not meet the requirements of real-time online control of traffic flow,and it does not involve the theory of complex networks system and synchronization control.Meanwhile,in the traditional coordinated control,coordinated multi-on-ramp metering has the best performance.However,there are also some deficiencies in the complexity of the solution of the model,dependence on the prediction accuracy,no feedback mechanism,difficulty in large-scale network applications,or the need to specify the scope of coordinated control signals in advance.Based on this,this paper attempts to establish a node coupling model of complex networks for urban expressway based on Cell Transmission Model(CTM)by analyzing the characteristics of traffic flow.The most effective control strategy under rush hour is proposed through the analysis of northwest ring of the expressway in Tianjin.The main work can be summarized as the following aspects:(1)Based on the research results of scholars at home and abroad,chaotic identification method,chaos control principle and the characteristics of complex network of urban expressway are analyzed in depth which provides a theoretical basis for the establishment of a node coupling model of complex networks for urban expressway.(2)Combined with existing CTM,Variable Cell Transmission Model(VCTM)with different cell lengths,traffic flow characteristics of urban expressways and complex networks characteristics,a node coupling model of complex networks for urban expressway is established,and the change of traffic flow under different combinations is analyzed.It provides a model for the study of coordinated control of urban expressway.(3)On the basis of the existing coordinated controller design,the coordinated controller of multi-on-ramp with Controlling chaos as the goal is proposed and the control strategy is determined.The diversion node corresponds to the entrance ramp on which the control signal is to be applied,and the stability conditions for the synchronization of the urban expressway network system are deduced to obtain a pinch node and a feedback gain matrix.(4)The problem of synchronization of complex networks control of urban expressway in the congestion condition is studied through the analysis of northwest half ring of the expressway in Tianjin.Under the condition of the changeable traffic demand,the control effects are compared by four control algorithms which include pinning chaos control,global control,stochastic control and CORDIN control.The results of the example indicate that traffic jams can be suppressed at the cost of the small control ranges.And then the goals of enhancing the road operating efficiency can be realized.The effect is superior to that of the traditional coordinated control methods and the method can be further extended to large-scale urban traffic network system.