Research on hierarchical control of Automobile Adaptive Cruise system based on the mode switching

Automobile Adaptive Cruise system sends commands from the upper-level controller to the lower-level controller(throttle or brake controller) through the hierarchical control, which enables the automobile to accelerate, decelerate or keep constant speed automatically in order to maintain the desired distance between the automobiles. The adaptive cruise control modes are divided into the automobile speed control mode and the automobile distance control mode. Considering the game between the two modes, the strategy is established according to the relationship between the distance and the relative velocity to achieve a smooth switch between speed control mode and automobile distance control mode. The desired acceleration in different modes are controlled by PI control and fuzzy control so as to establish the upper-level controller. The desired acceleration and desired deceleration are distinguished according to the switching logic between the brake and the accelerator so as to obtain the lower-level controller. Finally, the simulation is carried out to the adaptive cruise automobile by the CarSim and Matlab/Simulink in the complex working conditions. The results show that the automobile tracks the one ahead steadily by the proposed control method, and the AAC system with the improved mode switch could obtain more steady response.