Study On Control Strategy Of Automotive Adaptive Cruise Control System

Adaptive cruise control system is an important part of advanced driving assistant system.It can reduce the drivers' operating burden,improve the road traffic rate,comfort and fuel economy of automobiles.It has important engineering application value.Control strategy is the core content of adaptive cruise system research,so the research on control strategy of adaptive cruise system is of great significance.Firstly,the functional requirements of the automotive adaptive cruise system are analyzed,the constant time headway algorithm and the variable time headway algorithm are analyzed,the improved design method of the variable time headway algorithm is proposed.The concept of reaction time headway is proposed,the mode switching strategy based on reaction time headway is designed.The vehicle longitudinal dynamic model is established and its dynamic performance is verified.Inverse longitudinal dynamics model of vehicle is established,including driving/braking switching strategy,inverse engine model and inverse braking system model.Then,the adaptive cruise control strategy based on change-velocity integral PID control is studied.Using change-velocity integral PID control,the adaptive cruise PID control strategy algorithm is established in MATLAB/Simulink development environment,and the simulation analysis of the PID control strategy algorithm is carried out under the cruise control and the following control modes respectively.It is concluded that the adaptive cruise PID control has the advantages of fast response and small overshoot in the cruise control mode,but the control effect is not ideal under the complex conditions of the following control mode,therefore,the MPC method is considered in the following control mode of ACC system.In order to achieve good performance under the following control mode,this dissertation studies the adaptive cruise control strategy based on MPC.The prediction model of acceleration control is established,and the rolling optimization and error feedback correction analysis are carried out.Based on the development environment of MATLAB/Simulink,an adaptive cruise MPC control strategy algorithm is established to realize the control of the velocity and the time headway of the adaptive cruise vehicle of the workshop.Finally,the strategy of adaptive cruise control system proposed in this dissertation is simulated.The co-simulation platform of MATLAB/Simulink and CarSim is established.The performance of ACC system under three typical car-following conditions,i.e.constant velocity,acceleration and deceleration,is analyzed.Different car-following velocities and different acceleration and deceleration intervals are set respectively.The results show that the adaptive cruise control strategy presented in this dissertation has better performance under the following control mode.