On Leader-Follower Strategy And Control Method For Unmanned Vehicle Following

As a basic behavior of cooperative driving,vehicle following is of great concern to research.This thesis is major in the following behavior of unmanned vehicle on the road.To ensure the longitudinal and lateral safety of the vehicle,a following strategy is needed.In order to keep the vehicle following stably and accurately,it is necessary to study the longitudinal and horizontal control for rear vehicle,taking the interference factors of the driving circumstance into account.As to test and verify the effectiveness of the controller,dynamic model for vehicle driving and steering is needed to be established.In view of the issues above,research work introduced bellow has been done in this thesis.Firstly,for the longitudinal and lateral safety in following process,this thesis proposed a kind of leader-follower strategy based on virtual leader.The strategy insures the safe distance both timely and spatially,and makes the follower drive in line with the leader,which guarantees the lateral driving safety of the follower.Otherwise,the proposed following strategy converts the problem of following a vehicle into a problem of following a dynamic trajectory.Secondly,this thesis analyzed on the process of the follower following desired trajectory,established the following error model,then,designed PID controller for both longitudinal as well as lateral motion and carried out a simulation test.Simulation results show that PID controller can help the follower follow the leader well in ideal conditions.Considering the complex driving environment,white noise was added into the simulation of the following process to verify the performance of PID controller under interference.Thirdly,concerning about the insufficient anti-interference ability of PID controller,this thesis designed a new controller based on sliding-model control theory.Taking the effect of random disturbance on the following system into account,the robust compensations related to the upper and lower bounds of the disturbance were designed.Then,a simulation of vehicle following under complex conditions was done to test effectiveness of the sliding-model controller and get an ideal testing result on the kinematics level.Finally,in order to validate the designed car-following control system more in line with the actual driving conditions,a simple and accurate simulation model was established in this thesis for vehicle driving and steering dynamics.This simulation model includes key components such as engine,transmission system,brake system,steering system,and the dynamic modeling of vehicle driving process.Added this model into the simulation,the validity of the car-following control system is verified.