Anti-lock Brake System (ABS): Features/Construction

When the brake pedal is depressed during driving, the wheels can lock before the vehicle comes to a stop. In such a case, the maneuverability of the vehicle is reduced if the front wheels are locked, and the stability of the vehicle is reduced if the rear wheels are locked, creating an extremely unstable condition. The ABS precisely controls the slip rate of the wheels to ensure the grip force of the tires, and it thereby ensures the maneuverability and stability of the vehicle.

Judging the vehicle speed, the ABS calculates the slip rate of the wheels based on the vehicle speed and the wheel speed, then it controls the brake fluid pressure to attain the target slip rate.

Grip Force of Tire and Road Surface 

Fig 1: Grip Force Graph

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Slip Rate 

Fig 2: Slip Rate Chart

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 3: Anti-Lock Brake System - System Diagram

Courtesy of AMERICAN HONDA MOTOR CO., INC.