ANTILOCK BRAKING SYSTEM Le Thanh Phuc Faculty of Automotive Engineering University of Technical Education Ho Chi Minh City Email: phuclt@hcmute.edu.vn Introduction • ABS is a safety-related feature that assists the driver in deceleration of the vehicle in poor or marginal braking conditions (e.g wet or icy roads) • In ABS-equipped cars, the wheel is prevented from locking by a mechanism that automatically regulates the force applied to the wheels by the brakes to an optimum for any given low-friction condition Slip ratio • The car is traveling at a speed U and the wheels are rotating at an angular speed ωw where and where RPMw is the RPM of the wheel in revolutions per minute When the wheel is rolling (no applied brakes) where rw is the tire effective radius • The braking and lateral forces are proportional to the normal force (from the weight of the car and from inertial forces due to deceleration) acting on the tire/road interface and the friction coefficients for braking force (Fb) • The torque Tw applied to the wheel at the road surface by the braking force Fb • The braking torque Tb is applied to the disk by the brake pads in response to brake pressure pb • In accordance with basic Newtonian mechanics, the wheel torque Tw is related to braking torque and wheel deceleration by the following equation: • The longitudinal motion of the vehicle is described: mU = ∑ F b where m is vehicle mass, Fb is force acting on the tires when braking  ...Introduction • ABS is a safety-related feature that assists the driver in deceleration of the vehicle in poor or marginal braking conditions (e.g wet or icy roads) • In ABS- equipped cars,