| With the new four modernizations of automobiles and the introduction of new concepts and development directions of automobiles such as software-defined automobiles,automobiles are also developing towards more intelligent and comfortable directions.The active safety technology represented by the collision avoidance system had played an outstanding advantage in avoiding collision or reducing the danger degree of collision injury.The complex traffic environments give more demands for control systems.Therefore,it is vital to study the collision avoidance strategy under complex traffic scene.Based on the comprehensive analysis of the domestic real traffic scenes,the principle and key technologies of the longitudinal control system were also more clearly understood,and the overall scheme and control strategy of the longitudinal control system were formulated.A simulation traffic scene was built and the dynamics of vehicle was modeled.The inverse dynamics and switching logic were designed in Simulink.Then the algorithm was verified,which was ready for subsequent modeling and joint simulation verification.Based on MATLAB/Stateflow and MATLAB-Function,the switching moedls of three subsystems were established.Considering that the emergency braking model based on residual collision time TTC fails when the relative speed of the two automobiles was small,three-stage braking schemes based on expected deceleration and TTC-1,which were based on the reciprocal of residual collision time,were designed respectively by taking the TTC value of 5s as the critical point.Therefore,the driver’s ride comfort and road traffic efficiency were fully considered.A layered controller was build including upper and lower subsystem.Finally,with the help of Pre Scan,Car Sim and Simulink,an intelligent automobile model-in-the-loop co-simulation platform was designed.Through the establishment of typical scenes and complex traffic scenes,the longitudinal collision avoidance control algorithm was verified and the results were analyzed. |
