DESIGN OF FUZZY LOGIC CONTROLLER BASED ANTILOCK BRAKING SYSTEM FOR PASSENGER CARS

Abstract

An Antilock Braking System (ABS) is designed to prevent wheel lock up when brakes are applied. But the behavior of various road surface is non-linear which makes it impossible to correctly predict the optimal brake forces that can be applied to minimize stopping distance while maintaining steer ability. In this thesis, a quarter car model has been selected and a mathematical and MATLAB/Simulink model of some of components of an ABS has been developed. A Fuzzy Logic Controller (FLC) was implemented to utilize different variables, such as optimal slip and brake pedal force based on a parameter, where error of slip and rate of error as input parameter and change of pressure as an output parameter. Then, the characteristics of the slip curve was analyzed throughout the entire braking period with and without FLCs. The antilock braking system with bang-bang control would stop the vehicle in 16.3 seconds, however, it fluctuated in slip, whereas using fuzzy controllers would stop the vehicle in 2.46 seconds. Fuzzy logic control process mimics human brain thinking because of decision making hence provides better functionality when handling real time control of the parameters than a simple bang-bang controller. Fuzzy logic controller is better in control slip, steer ability, and braking.