Research On CACC Control Strategy And Optimization Of Operation Process Under Vehicle Networking Environment

Under the vehicle network environment,CACC realizes the data interaction between vehicles,vehicles and roadside units with the help of specific communication functions,and realizes queue cruise control by integrating single vehicle sensor data and the shared data of the queue.This paper focuses on CACC communication requirements,control strategies and optimization and performance integration testing.The main work of this paper is as follows:(1)In order to improve the security and reliability of CACC communication,starting with the communication process of the subsystem,the method of calculating the queue safety distance under the condition of uniform braking is given.On this basis,the real-time requirement of the communication is analyzed.The RSU location strategy based on the maximum communication distance is proposed,and the best placement range is given.(2)A hierarchical CACC system controller is designed,and the frequency domain relationship between actual acceleration and expected acceleration is established to simplify the modeling process of the lower level dynamic model.On the basis of the existing variable car following strategy,the regulation factors related to the front vehicle speed are introduced to improve the system's volatility under start-up conditions.The method of calculating the expected acceleration under uniform speed and the temporary strategy when the distance parameter is lost is proposed,which improves the system security.(3)Aiming at the shortage of vehicle longitudinal acceleration control,an acceleration optimization control method based on PBPPID is designed.By adding PID control to the BP neural network model,the average error of the actual acceleration is less than 0.35m/s~2,and the adjustment time is reduced by 50%under extreme condition.By analyzing the influence of acceleration and acceleration change rate on the comfort degree,a comfort regulator based on fuzzy control theory is designed to optimize the CACC upper output.Under the starting condition,the mean square error of the expected acceleration is only 15%of that before optimization,which improves the ride comfort.(4)The CACC simulation system based on driving simulation platform was built independently,and its comprehensive performance was tested under three specific conditions.The results show that the CACC system in this paper can quickly correct the speed deviation and reduce the response time of the system under the bad road condition.Under the condition of emergency braking,the error of distance between vehicles is less than 10m,which greatly improves driving safety.Compared with the traditional ACC system,the CACC system breaks through the limitation of the sensor precision,reduces the lag of the system,and the speed fluctuation error of the steady state with the car is less than 0.1m/s,so it can complete the cruise task better.