Abstract: An antilock brake control system for a vehicle includes a control start determining device for determining that an antilock brake control should be started, in response to a slip rate calculated based on a wheel speed and a presumed vehicle speed exceeding a start determination threshold value determined as a function of the presumed vehicle speed. The control start determining device changes the function of the presumed vehicle speed for calculating the start determination threshold value, based on the state of the antilock brake control for a wheel other than a wheel which is subjected to the determination by the control start determining device, and the results of the determinations by the road surface friction coefficient determining device and the bad-road determining device. Thus, appropriate antilock brake control for the situation of a road surface is conducted.

Abstract: An antilock brake control system for a vehicle includes a PID calculating device for carrying out a PID calculation based on a deviation between a target slip rate determined based on a presumed vehicle speed and a slip rate, and the operation of a braking liquid pressure regulating device is controlled based on the result of the calculation in the PID calculating device. The PID calculating device is arranged to limit the PID calculation value within a predetermined limit value. Thus, it is possible to enhance the control followability in carrying out the control of a braking pressure based on the PID calculation.

Abstract: An antilock brake control system in a vehicle is designed to retard the pressure increasing timing in one of front and rear wheel braking liquid pressure regulating devices which corresponds to a wheel having a smaller load share, until the wheel speed of such wheel is started to be reduced while following an actual vehicle speed after being restored to near the actual vehicle speed, when both of front and rear wheels are in antilock brake-controlled state.

Abstract: An antilock brake control system in a vehicle includes a PID calculating device for carrying out a PID calculation based on a deviation between a target slip rate determined based on a presumed vehicle speed and a slip rate, so that the operation of braking fluid pressure regulating device is controlled based on the result of the calculation in the PID calculating device. In the antilock brake control system, a braking pressure control mode is decided based on the result of comparison of a PID calculation value calculated in the PID calculating device with a predetermined threshold value, so that the operation of braking fluid pressure regulating device is controlled in such control mode. When the amount of variation in PID calculation value within a predetermined time exceeds a predetermined value, a control mode different from a control mode decided from a current PID calculation value is selected.