MOHAMMED H. ALMOLA, M. MAILAH, A.H. MUHAIMIN AND M.Y. ABDULLAH Department of System Dynamics and Control Faculty of Mechanical Engineering Universiti Teknologi Malaysia 81310 UTM Johor Bahru, Johor, MALAYSIA daadmaster@gmail.com, musa@fkm.utm.my Antilock braking systems (ABS) are safety and control devices implemented in ground vehicles that prevent the wheel lockup during panic braking. The existing ABS controls have the ability to regulate the level of pressure to optimally maintain the wheel slip within the vehicle stability range. However, the ABS shows strong nonlinear characteristics in which the vehicles equipped with the existing controllers can still have a tendency to oversteer and become unstable. In this paper, a new intelligent robust control method based on active force control (AFC) strategy is proposed via a simulation study. It is designed and implemented in a hybrid form by having the AFC loop directly cascaded in series with a fuzzy logic (FL) selftuning proportionalintegralderivative (PID) control as the outermost loop position control for the effective overall performance. From the results, it is evident that FLPID with AFC scheme shows faster and better response compared to the classic PID controller for the given loading and operating conditions. The incorporation of the AFCbased scheme into the ABS serves to provide enhanced performance that has great potentials to be implemented in realtime system. Antilock brake system, AFC strategy, fuzzy logic, PID controller Antilock brake systems (ABS) are common in today’s passenger car, and feasible with the availability of low cost sensors and low cost microcomputers. The main components of an ABS are an electronic control unit, a brake force actuator, and wheel speed sensors. The function of an ABS is to prevent wheels from being totally locked during panic braking or braking on slippery road surface. The objective of an ABS is to achieve the shorter stopping distance and maintain a good steering stability during braking. As a mechanical system, the first ABS was developing for airplanes in 1947 [1]. For automotive fields, it was too expensive to design and develop an ABS at that time. In 1954 the first trial for automotive using ABS and was on a limited number which were fitted with an ABS from a French aircraft. In the late 60's, Ford, Chrysler, and Cadillac offered ABS on very few models. These very first systems used analogue computers and vacuumactuated modulators [2]. At that time, it was not commercially successful [3]. The development of ABS was actually started in the 1970s. Mercedes and BMW start to introduce (ECU) electronicallycontrolled ABS systems and that was in the late 70's. By 1985, Bosch ABS systems have been used by each of Audi, BMW [2]. The unknown parameters of the environment associating the vehicle and nonlinearity characteristics in its performance, made this mechanism as a nonlinear system. Many researchers used control strategies to hold this phenomenon one of them is fuzzy control.The other approach that is proposed in the design of the ABS controller is fuzzy PID control (FLPID) design method which is known as a hybrid control strategy and is the combination of fuzzy control and conventional PID control method. The main advantage of the FLPID is that is used fewer fuzzy rules than FC [4]. Yet another robust control scheme known as active force control (AFC) has emerged and has been shown to be far superior compared to the conventional PID control method in controlling various dynamical systems [510]. The principal objective of this study is to propose a hybrid controller, comprising a fuzzy logic with PID controller and a new robust active force controller applied to an ABS. The behaviour of the ABS with classic PID controller is deemed not appropriate, because when the vehicle tries to follow or track the slip ratio, it takes a longer time to reach the reference input slip. To overcome this problem, Latest Advances in Systems Science and Computational Intelligence ISBN: 978-1-61804-094-7 210