Fuzzy logic based adaptive cruise control with guaranteed string stability

Recently, many topics in intelligent transportation system (ITS) are researched. One of the topics is adaptive cruise control (ACC). The adaptive cruise control systems should be designed such that string stability can be guaranteed in addition to that every vehicle in a string of ACC vehicles which use the same control law must track any bounded acceleration and velocity of its preceding vehicle with a bounded spacing and velocity error. The purpose of this paper is to design fuzzy logic based ACC which guarantees string stability. The feature of this controller is adaptation to a target speed and speed reduction to keep a safe distance from preceding vehicle and also guarantees string stability. This controller controls throttle angle and brake pressure. The performance of this controller has been investigated through computer simulation using Carsim of Mechanical Simulation Corporation. The results show that the proposed controller can guarantee safe time gap and string stability satisfactorily.