Research On Vehicle Adaptive Cruise Control Strategy

As a part of vehicle safety technology,adaptive cruise control(ACC)system plays a certain role in ensuring the safety of riding and reducing road traffic accidents.The control strategy has a great impact on the performance of ACC system.In this thesis,the control strategy is studied and the effectiveness of the designed control strategy is tested in the Car Sim/ Simulink simulation platform.The main research contents of this thesis include:(1)The functions of each part of ACC system are analyzed,and the overall structure of ACC system is designed by using layered scheme.The distance model of for vehicle driving safety is studied,and the switching logic between constant speed cruise and following mode of ACC system is designed.(2)According to the driving and braking conditions,the reverse engine model and the reverse brake model are established,and the switching logic of the two conditions is designed.Based on the PID algorithm,the ACC lower controller is designed to control the vehicle follow the desired acceleration.(3)The upper controller of ACC system is designed.In constant speed cruise mode,PID algorithm is used to control vehicle speed.In following control mode,vehicle speed,distance,vehicle comfort,fuel economy and other factors are considered.MPC algorithm is used to solve the multi constraint problem,and the expected acceleration is obtained.To improve the environmental adaptability of ACC system,fuzzy control is used to determine the following weight coefficient in different environments.(4)Simulink/Carsim simulation platform is built.The control strategy designed in this thesis is simulated and analyzed in six common urban working conditions,including constant cruise,follow driving,front vehicle cut out,front vehicle cut in,front vehicle emergency braking and front vehicle "start stop".The results show that the control strategy can ensure the safe driving of the vehicle,and has good comfort as well as fuel economy.