Research On Fuzzy Control Strategy Of Automotive Adaptive Cruise Control System

Adaptive Cruise Control System (ACC) is an important component in the research ofAdvanced Vehicle Control System (AVCS). On the on hand, ACC systems aim atenhancing driving comfort, reliving driver stress on long trips so that it can reduce theaccidents rate caused by driver fatigue; on the other hand, ACC systems could also smoothtraffic flow and lower traffic jams.The main function of ACC systems are detecting following vehicle driving state by theradar installed in front of the vehicle. If the following vehicle travels within certainrelatively spacing, the host vehicle would enter car-following model and keep a safedistance with the following vehicle. However, if not, the host would enter cruise model atpreset velocity. This adaptive function makes it possible for vehicles to implementautomated longitudinal speed control without drivers intervene. The key techniques of ACCsystems involve radar technology and adaptive control algorithm issues. Radar technology,which in recent years has been well studied, could satisfy the need of on-board vehicles.Adaptive control algorithms or control strategies, to some content, play the most importantrole in deciding the efficiency and accuracy of ACC systems.This paper summarizes the background information of researched results of ACCcontrol strategies, considering the weakness point of the traditional ACC control methodthat aims at modeling accurate mathematic model (cannot fit the nonlinearity of vehicle)but failed to considering human factor, as well as basing on the advantage of fuzzy controlwhich can include driving knowledge, then proposes a ACC fuzzy control strategy thatallows for driver knowledge. Depending on driver experience, which involves theaccelerating or decelerating behavior under certain spacing or velocity, a four inputs(speed_error、timegap_error、acceleration and de_timegap) and two outputs (throttle andbrake) controller has been designed.At the same time, to test the validation of the proposed control strategy of ACC system,considering the need of the simulation, a look-up table based modeling engine method hasbeen proposed by Matlab/Simulink software to finish the vehicle longitudinal model, whichrepresents simplicity and efficiency. In simulation, two scenarios including cruise modeland car-following model will be tested.Finally, compared with the traditional ACC control method, by calculating the steady state variance of system and corresponding speed, the proposed fuzzy control methodperformed well in both cruise and car-following condition.