ANTILOCK BRAKINH SYSTEM

ANTILOCK BRAKING SYSTEMLe Thanh Phuc Faculty of Automotive Engineering University of Technical Education Ho Chi Minh City Email: phuclt@hcmute.edu.vn... • ABS is a safety-related feature

ANTILOCK BRAKING SYSTEM

Le Thanh Phuc

Faculty of Automotive Engineering

University of Technical Education Ho Chi Minh City

Email: phuclt@hcmute.edu.vn

• 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

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Slip ratio

• The car is traveling at a speed U and the wheels are rotating at an angular speed ωw where

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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

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• 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)

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• The torque Tw applied to the wheel at the road surface by the braking force Fb

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• 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:

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• The longitudinal motion of the vehicle is described:

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b

F U

where m is vehicle mass, Fb is force acting on the tires when braking

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