The Design And Research Of Vehicle Rear-end Collision Avoidance System In Highway Based On DSRC

With the increasing of the number of cars in our country and the scale of highway construction is expanding constantly,the automobile is developing rapidly,at the same time,the traffic accident has become a global security problem.The data analysis shows that the vehicle rear end collision accounts for about 10%of the total traffic accidents,while in the highway traffic accidents,the proportion is as high as 40%.Due to the highway traffic accident caused by the loss of serious and great harm,the highway rear end collision safety problem is urgent to solve.Based on vehicle system dynamics,modern control theory,advanced sensors and information and communication technology,the main content of this thesis take the vehicle rear end collision avoidance as the research object and is to do research on the two key technologies that are the vehicle safety distance model and adaptive data broadcast algorithm.The accuracy and reliability of the safety distance estimation have a direct impact on traffic safety,road traffic efficiency and ride comfort,which is the basis for preventing rear end collision system.The traditional safety distance model is based on the car.If the safety distance is set to be conservative,the false alarm rate will be higher,which will reduce the driving efficiency.If the safety distance is set to non conservative,it is easy to cause the system alarm is not timely,which will directly affect the safety of driving.To solve the above problems,the braking process is analyzed,and this paper presents a new model based on the safety distance of vehicles in front,which is a good solution to the contradiction between false alarm rate and alert timeliness in traditional model.The vehicle moves at high speed and the channel medium is in the shared state in the vehicle environment.To broadcast the message blindly at the maximum transmission frequency can not guarantee that all vehicles on the road can be received,but easily lead to network congestion.Sending packets at a constant frequency is clearly not optimal.In order to solve the above problems,data transmission delay and packet loss rate are modeled by introducing traffic following model and two point transmission probability model for wireless transmission channel.Then an adaptive broadcast algorithm based on DSRC is designed,which can adjust the frequency of the broadcast data packet of the vehicle terminal dynamically according to the transmission delay and the packet loss rate.The invention can effectively reduce the delay and packet loss rate of wireless transmission,and the energy consumption and save the bandwidth to the maximum extent.The simulation and analysis were carried out with VanetMobiSim and network simulator version 2(NS2).The feasibility and effectiveness of the adaptive data broadcasting algorithm are verified compared with none broadcast frequency adaptive algorithm simulation results.The simulation and analysis were carried out with PreScan and Matlab/Simulink.The validity and stability of the rear end collision avoidance algorithm are verified under three conditions,such as the static front vehicle,the sudden deceleration of the front vehicle and the uniform speed of the vehicle at the same time,which is great significance to improve road traffic safety and traffic efficiency.