Longitudinal Following And Path Tracking Control For Intelligent Vehicle Platooning

Intelligent transportation system is an extremely important part in the development of smart city,and its essence is a new integrated transportation intelligent management system which uses computer engineering,transportation engineering,communication engineering,electronic sensor technology,control engineering and other technologies to help the development of urban surface transportation.In this thesis,aiming at the vehicle intelligent control system in intelligent transportation,the control problem of intelligent vehicle platoon is studied deeply.Vehicle platoon can improve road traffic flow,reduce traffic accidents,reduce environmental pollution and save energy.The collaborative control of intelligent vehicle platoon is very important for increasing urban traffic flow,reducing fuel consumption and easing traffic pressure.Aiming at the longitudinal speed following control of vehicle platoon,this thesis designs a hierarchical longitudinal controller of platoon based on the nonlinear PID control method and the vehicle inverse dynamics model to achieve the functions of cruising speed and keeping formation when the follow-up target being the speed of previous vehicle and leading vehicle.The lateral path tracking control of platoon in this thesis is divided into three steps,i.e.,ideal lateral acceleration preview,lateral acceleration-front wheel angle vehicle characteristic modeling and identification,and lateral acceleration adaptive PD control based on the preview follow theory and PID control theory with the follow-up target being the trajectory of previous vehicle,and the yaw angle is followed based on PID feedback control.The main research contents and conclusions are as follows:Firstly,according to the laws of the control effect of different PID parameters,the PID parameters are non-linear processed,which is related to the deviation of vehicle state,and the nonlinear PID controller is designed.Based on the PLF communication topology and the constant time-gap policy,the desired speed and acceleration are calculated when obtaining the position,speed and acceleration of the previous vehicle,the position,speed and acceleration of the leading.Through the joint simulation of Car Sim and MATLAB/Simulink,the results show that the maximum spacing deviation is 0.4m,and compared with the PID controller,the control effect of the nonlinear PID controller designed in this thesis is improved and the method is better.Secondly,based on the vehicle longitudinal inverse dynamics model and PID feedback control,the vehicle longitudinal lower controller is designed.Based on the output of the nonlinear PID controller,i.e.,the desired speed and acceleration,the lower controller calculates the control quantity,i.e.the throttle opening or the brake pressure according to the vehicle longitudinal inverse dynamics model and PID feedback control.Through the joint simulation of Car Sim and MATLAB/Simulink,the results show that the maximum deviation between the expected speed and the actual speed is 0.45m/s,and verify the accuracy and feasibility of the vehicle lower tracking control method.Finally,based on the preview and follow theory and PID control theory,the lateral controller is designed.The yaw angle and trajectory of the previous vehicle are the following targets.According to the simplified vehicle two degree of freedom dynamic model,the lateral control of the platoon is divided into ideal lateral acceleration preview,lateral acceleration-front wheel angle vehicle characteristic modeling and identification,and lateral acceleration adaptive PD control to follow the trajectory of the previous vehicle and the yaw angle is followed based on PID feedback control.The simulation results based on Car Sim and MATLAB/Simulink show that the maximum lateral error is 0.45m,the maximum range of vehicle slip angle is-0.6~°?0.6~°,and the maximum range of tire slip angle is-4~°?5~°,which show that the lateral control method can not only effectively control the vehicle follow the yaw angle and trajectory of the previous vehicle,but also ensure the nice stability of the vehicle in the lane change.