Control Strategy And Simulation Verification Of Vehicle Adaptive Cruise System

Adaptive cruise control(ACC)system is one of the key technologies of intelligent assisted driving vehicles,which has become the focus of attention.In this paper,taking the adaptive cruise control system as the object of study,the dynamic modeling and control strategies are studied.The main works of this thesis are as follows:Firstly,the research background and significance of this paper is elaborated,and latest research achievements in recent years are discussed from four aspects,which include the current application situation of ACC system,vehicle longitudinal dynamics model,driver car behavior and adaptive cruise control algorithm.On this basis,the research content of this paper is put forward.Secondly,the function requirement and control target of adaptive cruise control system are analyzed,the architecture of adaptive cruise control system is designed,composing of the upper controller,lower controller and vehicle model,which provide the technical route for the modeling and control strategy research in following chapters.Again,taking a vehicle equipped with automatic transmission as research object,the basic structure of the vehicle longitudinal dynamics system is analyzed.Simulation modeling of vehicle longitudinal dynamics based on Matlab/Simulink software environment is conducted,which used for control strategy design and simulation verification in later chapters.Then,based on the function requirement and control target for adaptive cruise control system,a layered control algorithm is investigated.The integrated longitudinal kinematic model is established in the upper controller,which includes the vehicle model,the kinematics between vehicles and the time interval.The desired acceleration is calculated through linear quadratic optimal control theory,taking into account the vehicle distance,relative speed and acceleration of three major performance indexes.In the lower controller,the vehicle inverse longitudinal dynamics model including the drive/brake switching logic,the inverse engine model and the inverse brake model is established,and the PID algorithm is used to achieve acceleration correction.Through switching control of throttle and brake,the actual acceleration of the vehicle can track the desired acceleration of the upper control output.Finally,in order to verify the validity and effectiveness of the designed control algorithm,an adaptive cruise hierarchical controller is built based on the Matlab\Simulink software environment,and simulation verification is carried out under a variety of working conditions combining with the vehicle dynamics model.