Optimal Control Method Of Variable Speed Limit At Freeway In Vehicle-infrastructure Cooperative Environment

Due to limited land resources and high infrastructure investment required for new or expanded highway,it is difficult to effectively solve the current traffic problems by increasing the road traffic supply method.Applying active traffic management control to improve the efficiency and safety of expressways has become a new consensus in the industry.As an important way of active traffic management control,Variable Speed Limit(VSL)has received extensive attention from traffic managers all over the world and has been put into use in many countries.The development of the new generation of information technology has led to the transformation of the two major industries,automobile and transportation,which promotes vehicle infrastructure cooperative system(VICS).Vehicle-related technology and its application have been incorporated into the development strategy of China’s intelligent transportation system.Faced with the real-time information exchange problem of variable speed limit control,VICS based on wireless sensor technology,that interconnect information between vehicles and infrastructure,provides a new platform for the development of domestic variable speed limit system.Based on the real-time traffic data and new information interaction methods provided by CIVS,this paper proposes an optimization control method for variable speed control at the vehicle-infrastructure coordination environment,which lays a theoretical foundation for expressway management in the connected environmentThe paper studies the key issues in variable speed control at the vehicle-infrastructure cooperative environment.Firstly,the control characteristics of the variable speed control under the vehicle-infrastructure cooperative environment are analyzed.Then the macroscopic traffic flow model of the variable speed limit control is constructed under the vehicle-infrastructure cooperative environment.The variable speed limit control method at the vehicle-infrastructure coordination environment is proposed based on model predictive control theory,and the improved genetic algorithm is used to optimal control parameters.Finally,the control effect of the variable speed limit control method proposed in this study is analyzed and compared by simulation.The thesis includes the following contents.Firstly,the vehicle-infrastructure cooperative environment is analyzed,including the highway vehicle infrastructure cooperative system architecture and control information of the variable speed limit control under the vehicle-infrastructure cooperative environment.Then,the research environment hypothesis is proposed and two types of control parameters are conveyed in vehicle-infrastructure cooperative environment.With the cell length variation parameters introduced,the cell transmission model was redeveloped to simulate the influence of the variable speed limit control on the road traffic flow,including variable speed limit control area.Secondly,the model predictive control is chosen as the framework of the variable speed limit control algorithm.In the system,the proposed variable speed control macroscopic traffic flow model is used as the prediction model and the optimization objective function and constraints are built to improve the system road traffic efficiency.The traditional genetic algorithm is optimized for the constraints of the speed limit and the cell length variation parameters,which is used to calculate the control parameter.Finally,a numerical simulation platform is constructed to simulate and analyze the variable speed limit optimization control method in the vehicle-infrastructure cooperative environment.The results show that compared with the non-control state and the traditional variable speed limit control method with only speed limit value,the control method proposed in this paper can effectively eliminate the congestion of the highway bottleneck area.