Car-following Behavior Analysis And Platoon Control Under Mixed Traffic Flow

With the development of automatic driving technologies and networking technology,the mixed traffic flow,which consists of Connected Autonomous Vehicle(CAV),Autonomous Vehicle(AV)and Human-driven Vehicle(HDV),will exist for a long time in the future.In order to study the car-following behavior of different types of vehicles,mixed-vehicles car-following modelling has become one of the hot topic in microscopic traffic flow simulation.However,most studies could not accurately describe the car-following behavior of different types of vehicles in mixed traffic flow,as well as the mutual influence and decisions.Therefore,this paper constructs a carfollowing model considering interaction potential of multiple front and rear vehicles and the differential deceleration strategies for CAV.By introducing molecular dynamics,the model also quantitatively expresses the influence degree of a surrounding vehicle on the host vehicle.The velocity of multiple front vehicles and headway between each of them and the host vehicle are used to express the influence.Besides,according to the headway between the host vehicle and the front vehicle,the applicability of the influence from multiple vehicles is defined.In addition,a mixed-vehicles car-following model for two types of vehicles(AV and HDV)is established,which considers the drivers' characteristics and different types of the nearest front vehicle.Based on the stability analysis of the platoon in mixed flow,the number of following HDV affected by CAV and AV is obtained,respectively.Then we study the impact of three driving styles for HDV on the number of influenced vehicles.The results of this paper can serve as an effective method for platoon control in the case of homogeneous flow or heterogeneous flow mixed with CAVs AVs and HDVs.Under the situation that it is difficult to carry out the field test of heterogeneous flow,this study provides theoretical basis and model support for the optimal control of driving behavior as well as simulation analysis.The main research content of this thesis includes the following aspects:(1)Modeling CAV's car-following behavior by introducing molecular dynamics and considering the information of multiple vehicles.The car-following behavior of CAV is analyzed in mixed traffic flow.A carfollowing model for CAV involves the velocity of multiple front and rear vehicles as well as the velocity difference and headway between each of them and the host vehicle.By introducing molecular dynamics,the model quantitatively expresses the change in influence degree of each front vehicle on the host vehicle with its location and velocity.According to the headway between the nearest vehicle and the host vehicle,the applicability of the influence from multiple vehicles is defined.Moreover,considering the influence of different types of the nearest vehicles on the car-following behavior of CAV in mixed traffic flow,this paper introduces the differentiated deceleration strategies and obtain four car-following models for CAV in case of the nearest non-CAV,including:(a)the nearest front vehicle is HDV or AV,and other vehicles are CAVs;(b)the nearest rear vehicle is HDV or AV,and other vehicles are CAVs;(c)the nearest front and rear vehicles are HDVs or AVs;(d)All vehicles are CAVs.Based on the Routh–Hurwitz criterion,the stability analysis of the proposed model is presented.Then,according to the data of CAVs following AVs or HDVs,the proposed model is calibrated,and its accuracy is verified.(2)Modeling AVs & HDVs' car-following behavior by considering driving characteristics.The influence of different types of the front vehicle on the car-following behavior of AV and HDV in mixed traffic flow is analyzed.The proposed model is calibrated,and the sensitivity is analyzed.Successively,its accuracy is verified.(3)Analyzing the stability of mixed traffic flow under different CAV proportions.Based on the randomness of relative spatial positions of vehicles in mixed traffic flow,this paper explores the mathematical expectations of the proportions of CAVs,AVs and HDVs,and analyzes the sensitivity about the minimum gap and headway.Considering the external disturbance and state delay in the platoon,this paper solves the transfer function of velocity disturbance by using the Laplace transform,and analyzes the open-loop amplitude-phase characteristics of the mixed traffic flow with different CAV proportions.Then,the function between velocity and headway at equilibrium is used to derive the fundamental diagram of the mixed traffic flow with different CAV proportions.The influencing factors of capacity in mixed traffic flow is studied,so as to provide a theoretical basis for improving the traffic capacity.(4)Analyzing the mixed-vehicles platoon under different driving styles and CAV proportios.Based on the simulation of the mixed-vehicles platoon,this paper sets up two scenarios: starting process and deceleration process under the guidance of different types of vehicles,and considers urban areas and emergency braking on expressways,respectively.The impact of three driving styles for HDV on the number of influenced vehicles is studied.Then,the number of following HDV affected by CAV and AV is obtained,respectively.The influence of CAV proportion on the stability of the platoon is explored.