Anti-skid braking system for automotive vehicle

Abstract

An anti-skid braking system for a vehicle, having (a) hydraulic brakes for wheels of the vehicle, (b) actuators provided for respective brake groups each including at least one of the brakes, for controlling a braking pressure or pressures of the brake or brakes of the corresponding groups, (c) speed sensors, at least one of which is provided corresponding to each actuator, for detecting speeds of the wheels, and (d) to controller operable for: normally presuming that an actual speed of the vehicle is represented by a highest one of the detected wheel speeds; after a deceleration value of the highest speed has exceeded a preset upper limit, fixing the deceleration value of the vehicle at the preset upper limit, and presuming the actual vehicle speed based on the upper limit; and calculating a slip amount of each wheel based on a difference between the presumed vehicle speed and the detected wheel speed, to control each actuator so as to prevent the wheel from skidding. The system includes a detector generating a signal whose level is changed in at least two steps indicative of at least two values of an actual deceleration value of the vehicle. The system further includes a setting device for determining the upper limit of the deceleration value such that the upper limit is changed with the detected actual deceleration value.