Research On Automobile Adaptive Cruise Control System

With the development of society, automobile are getting more and more popular. Driving safety, comfortableness and the intellectualization of vehicles are highly required. Adaptive Cruise Control system (ACC) is a new generation automobile pilot auxiliary system which develops on the traditional constant speed Cruise Control System (CCS). ACC can reduce driver's burden and increase the traffic flow. Also, it could reduce the fuel consumption and the exhaust pollution effectively, since ACC can make automobile's fuel delivery and the engine power coordination at the optimum condition. Therefore, the research on the ACC is an important issue.A complete vehicle longitudinal dynamics model and the practical safe distance model were established based on many research results of ACC. Vehicle longitudinal dynamics model includes the motor, the hydraulic torque converter, the automatic transmission, the vehicle dynamic system and the actuator etc. There were constant speed cruise and followed cruise modes in ACC. PID control was used in the constant speed cruise mode, while fuzzy self-adjusting PID control was used in the followed cruise mode. The online adjustment of control parameters of fuzzy self-adjusting PID can guarantee control precision of the speed. In order to realize the smoothly switch between the two modes, position controller based on the incremental algorithm was used in throttle control.Simulation experiments were done for the constant cruise pattern, followed cruise pattern and the brake control algorithm at the environment of Matlab/Simulink. The result showed that the ACC had good performance, which was able to improve traffic flow and ensure driving safety.ACC system was designed by using C8051F040 as calculation core. The hardware included the power circuit, the switching information acquisition circuit, the speed acquisition circuit, the distance acquisition circuit, the throttle position acquisition circuit, the clutch drive circuit, the actuator drive circuit and the A/D conversion circuit etc The software design was on Silicon Laboratories IDE. Main flowchart and subprogram flowcharts were given. The whole system was tested and the results were satisfied.