Cooperative On-Ramp Control Of Freeway In Mixed Driving Environment

In the traditional driving environment,restricted by technology and limited traffic flow information,it is difficult to solve the traffic congestion problem in the freeway confluence area.With the development of new technologies such as adaptive cruise control system and related communication means,automatic driving technology provides a new method for freeway on-ramp control.However,it will take some time for the popularization of automatic driving technology,and the hybrid driving environment will certainly exist for a long time in the future.Therefore,based on the project supported by the National Natural Science Foundation of China "Spatial and Temporal Evolution Mechanism and Dynamic Boundary Control Method of Traffic Congested Area in Intelligent Connected Environment"(No.52072108)and "Self-organization Mechanism and Associated Design Parameterization Optimization of Traffic Flow in Continuous Interchange of Expressway"(No.51878236),this paper takes mixed traffic flow as the research object.In order to optimize the operation efficiency of the freeway system,the related research is carried out.(1)By establishing a mixed traffic flow simulation platform,the classic vehicle following model and lane changing model are combined to study the basic graph variation rule of the mixed driving environment and the congestion propagation characteristics in the freeway confluence area respectively.(2)Based on the information provided by CAV(Connected and Automated Vehicle(CAV)vehicles,the position and speed of HV vehicles are predicted,and the CAV on the main line upstream of the converging area is implemented with the goal of minimizing the converging delay.To realize the cooperative control of traffic flow in multi-lane confluence area under mixed driving environment.(3)A single ramp confluence cooperative control method in pure CAV environment is proposed.Firstly,the lane changing model of the main line vehicle considering the demand of the on-ramp traffic is established.Secondly,the time window model of the onramp vehicle entering the mainline is determined according to the safe travel interval and acceleration time,and the cooperative decision control of the mainline vehicle and onramp vehicle on the expressway is realized.(4)The coordinated control model of adjacent ramp confluence zones on the freeway was established,and a coordinated control method of multi-ramp confluence under mixed driving environment was proposed by adopting the combined control of main line speed limit and ramp regulation.Through program design and simulation analysis,the results show that under low CAV permeability,the proposed method can provide more lane changing space for the on-ramp vehicle confluence,effectively reduce the conflict between the main line and the on-ramp vehicle,and reduce the total delay time and stopping times of vehicles in the control area.In the pure network environment,the proposed method can effectively reduce the total delay and stopping times,and increase the downstream outflow of the confluence bottleneck.In the continuous confluence scenario,the combined control of mainline speed limit and ramp regulation proposed in this paper is most effective for increasing output flow under the same CAV permeability.