Abstract: An antiskid control system for a four-wheel-drive vehicle is arranged to calculate a difference between an average of wheel accelerations of front wheels and an average of wheel acceleration of rear wheels. When the difference is greater than or equal to the vibration determination threshold, the antiskid control system determines that a driveline vibration is generated and executes a control for converging the driveline vibration.

Abstract: In an antiskid brake control system, an ECU estimates a wheel slip in accordance with a sensed wheel speed and controls a fluid pressure control valve for braking operation in accordance with the estimated wheel slip for an antiskid brake control, the fluid pressure being reduced when the wheel slip is enlarged and being increased when the wheel slip is lowered. When a vehicle-body speed is smaller than a predetermined quick pressure reduction prohibiting speed, the ECU performs a quick pressure reduction prohibiting control to restrain a quick pressure reduction having a greater reduction amount than a predetermined reduction amount.

Abstract: In an antiskid brake control system, an ECU is constructed to calculate a pseudo vehicle-body speed in accordance with a sensed wheel speed, calculate a target wheel speed in view of a predetermined slip ratio obtained in accordance with a calculated pseudo vehicle-body speed, carry out pressure reducing control by reducing the fluid pressure within a hydraulic unit when the sensed wheel speed is smaller than the calculated target wheel speed, estimate an amount of fluid stored in a reservoir, and correct the target wheel speed to lessen the slip ratio when the estimated fluid amount is greater than a predetermined value.

Abstract: An automotive brake control system with an anti-brake skid (ABS) unit which controls a wheel-brake cylinder pressure to each individual wheel cylinder of the road wheels to prevent a wheel lock-up condition during braking, and an ABS control unit being configured to be connected electrically to at least wheel speed sensors and the ABS unit to execute skid control having at least a reduce-pressure operating mode and a pressure build-up operating mode, when the wheel speed sensor signals indicate that at least one of the road wheels is locking up. The ABS control unit includes a road-surface-condition change determination section which determines, based on both a time length of brake-fluid-pressure control continuously executed during the skid control and a recovery acceleration of the wheel speed of the road wheel subjected to the skid control, whether there is a road-surface &mgr; change from low-&mgr; road to high-&mgr; road.

Abstract: An automotive brake control system with an anti-brake skid (ABS) unit which controls a wheel-brake cylinder pressure to each individual wheel cylinder of the road wheels to prevent a wheel lock-up condition during braking, and an ABS control unit being configured to be connected electrically to at least wheel speed sensors and the ABS unit to execute skid control having at least a reduce-pressure operating mode and a pressure build-up operating mode, when the wheel speed sensor signals indicate that at least one of the road wheels is locking up. The ABS control unit includes a road-surface-condition change determination section which determines, based on both a time length of brake-fluid-pressure control continuously executed during the skid control and a recovery acceleration of the wheel speed of the road wheel subjected to the skid control, whether there is a road-surface &mgr; change from low-&mgr; road to high-&mgr; road.