Modeling And Simulation Of Traffic Flow Mixed With Autonomous Vehicle Platoons

In recent years,due to the continuous increase of vehicle ownership,traffic congestion is becoming more and more serious.With the rapid development of transportation industry and automobile technology,intelligent transportation and intelligent vehicle will be integrated into our life.Vehicle platoon is a new type of intelligent vehicle driving mode under the intelligent transportation system.Its advent can effectively relieve the traffic pressure,improve the road capacity,and provide another possibility to solve the traffic congestion caused by traditional vehicles.Therefore,the research on the traffic flow characteristics of mixed vehicle platoon is a problem worthy of further exploration.This paper analyzes the characteristics of vehicle platoon and ordinary vehicle traffic operation characteristics of relevant literature,based on reasonable basic assumptions,establishes a model to analyze the impact of vehicle platoon on traffic.The main contents of this paper are as follows:(1)According to the traffic characteristics of ordinary vehicles,in the aspect of people vehicle road,the model is improved and distinguished according to the characteristics of vehicle platoon and ordinary vehicles in turn.Firstly,at the driver level,the driver characteristics of ordinary vehicles are described in terms of deceleration by risk-taking parameters and random slowing down;the difference between ordinary vehicles and vehicle platoon is described by the floating error of following speed;Secondly,the vehicle aspect: ordinary vehicles and vehicle platoon acceleration and deceleration,body length and other variables are distinguished;finally,the road aspect: in order to fit the actual traffic,the open boundary is adopted,and the corresponding main body boundary conditions are set.Based on the Na Sch model,according to the traffic characteristics of the above subjects,a cellular automata model framework is proposed.Then,considering the "hysteresis" effect caused by the cumulative update of displacement caused by the rounding function,the fractional part of the speed and displacement is recorded by accumulation,and the cell size and update time step are reduced.Based on the idea of classification modeling,a car following behavior model of cellular automata with vehicle platoon is established.Through the analysis of the car following model,the following conclusions are obtained: when a single lane follows,the flow,density and speed are basically obtained.With the increase of the mixed proportion of vehicle platoon,the road capacity increases,the final density concentration area begins to move backward and expand,and the distribution area of a large number of speed begins to expand to the higher speed area.The corresponding capacity of the vehicle platoon composed of two vehicles and three vehicles with the mixing ratio of 0.9 is about 1.6 and 1.9 times of the capacity of peers with the mixing ratio of 0.1;the larger the distance between vehicles in the vehicle platoon,the smaller the maximum capacity.With the same vehicle mix ratio,the more vehicles in the platoon,the larger the maximum capacity.(2)By studying the attributes and lane changing characteristics of various main vehicles,the condition of lane changing distance between different lanes and the difference of lane changing probability between ordinary vehicles and vehicle platoons are considered.Based on the STCA model,a three lane cellular automata lane changing model is constructed to describe the lane changing behavior of ordinary vehicles and platoon vehicles.The simulation results show that the number of lane change between ordinary vehicles and vehicle platoon is greater than that between ordinary vehicles.The higher the speed of vehicle platoon,the easier it is to be disturbed by vehicles coming from outside lanes,causing congestion and damaging the stability of driving system.