Abstract: An anti-skid control system for use in a motor vehicle which controls a braking pressure for a wheel of the motor vehicle to keep a slip of the wheel to an appropriate state by alternately performing a pressure-increasing operation and a pressure-maintaining operation in accordance with a slipping state of the wheel. The system first detects a slipping state of the wheel before performing the pressure-increasing operation on the basis of a vehicle speed and a wheel speed and then detects a slipping state of the wheel when a predetermined time period is elapsed from the pressure-increasing operation in a state that the braking pressure is maintained after the completion of the pressure-increasing operation so as to calculate a variation of the slipping state of the wheel on the basis of the detection results.

Abstract: A brake pressure control system for use as an antiskid braking control system, for example, for a motor vehicle, detects a skidding condition of a wheel of the motor vehicle based on a rotational speed of the wheel and a speed of the motor vehicle. A braking pressure applied to the wheel is increased and reduced according to control gradients, respectively, and the control gradients are continuously controlled so that the detected skidding condition will approach a target skidding condition. Times in which the braking pressure is continuously increased and reduced, respectively, are counted, and the control gradients are corrected depending on the counted times.

Abstract: An anti-skid control system for use in a motor vehicle which includes a braking pressure adjusting device associated in common with at least first and second wheels of the motor vehicle to control braking pressures applied thereto. The anti-skid control system includes first and second wheel speed sensors for sensing rotational speeds of the first and second wheels, respectively, and a vehicle state detector for detecting a state of the motor vehicle such as a speed of the motor vehicle. Also included in the anti-skid control system is a control unit for controlling the braking pressure adjusting device on the basis of the sensed rotational speeds of the first and second wheels and the detected state of the motor vehicle. The control unit determines a weighting coefficient on the basis of the detected vehicle state and calculates a weighted average wheel speed on the basis of the determined weighting coefficient and the sensed rotational speeds.

Abstract: Disclosed is an antiskid control system for a vehicle wherein the rotational acceleration of a wheel of the vehicle is detected and the rate of variation of the detected acceleration is detected upon the onset of speed reduction of the wheel. A pressure modulator, which is located in a hydraulic line between a master cylinder and a wheel cylinder, is responsive to the detected rate of variation of acceleration to provide a pressure relief action on the fluid pressurized by the master cylinder and supplies the modulated fluid to the wheel brake cylinder.

Abstract: In an antiskid control system, the acceleration of a vehicle wheel is detected and compared with a predetermined value. A first count value is incremented in response to the detection of the wheel acceleration exceeding the predetermined value. When this first count value exceeds a reference count within a first preset period, the road is interpreted as having a rough surface and a second count value is similarly incremented in response to the detection of the wheel acceleration exceeding the predetermined count. If the second count value does not reach the reference count within a second preset period longer than the first preset period, the road is interpreted as having a smooth surface. The gradient of brake hydraulic pressure of the vehicle is controlled in response to the different interpretation of the road surface.

Abstract: A pulse signal is generated by a wheel speed sensor with a frequency proportional to the speed of rotation of a vehicle wheel, the pulse signal comprising a plurality of frames each having a series of a predetermined number of pulses which are tended to be affected by noise and pulse mutilation. Pulses in each frame are counted and from the count is derived an instantaneous wheel speed value. The difference between the successively derived instantaneous speed values is taken and compared with a predetermined threshold. A first or a second indication is given in response to the difference being lower or higher than the threshold, respectively. If the first indication is given, output signals representing the average wheel speed and average wheel acceleration of the wheel are derived from the instantaneous speed values of successive frames.