Comparison of Sliding Mode Control and Fuzzy Sliding Mode Control in ABS System

Anti-lock Braking Systems (ABS) have been Developed to reduce tendency for wheel lock and improve vehicle control during sudden braking especially on slippery road surfaces. Sliding mode control is non-linear control method that alter the dynamics of a non-linear system by application of high frequency switching control. In SMC the feedback control law is not continuous function of time instead it switch from one continuous structure to another based on the current position in the state space. This discontinuity can excite unmodelled high frequency dynamics around a boundary layer of the sliding surface which involve the appearance of the chattering phenomenon. An intelligent fuzzy control method is very useful for this kind of nonlinear system. We develop a Fuzzy logic based sliding mode control scheme for ABS. This controller designed with three control objectives consist of reduce stopping distance, limit slip ratio and improve the performance controlling system on the ABS brake.