Abstract: The invention provides an anti-skid controller capable of correctly executing ABS control by accurately estimating a road surface .mu. without using additional sensors. Each wheel speed is detected, and acceleration of the vehicle body in a case where a wheel speed difference between front and rear wheels exceeds a specified value is determined. In this case, by using a change rate within a specified period of time with respect to a wheel speed of one in which wheel speed changing is small as the acceleration, a road surface .mu. corresponding to the acceleration is determined. Corrections regarding turning, bad road travelling, road surface changing, etc. can be carried out, by determining a lateral G based on a speed difference between left and right wheels.

Abstract: A braking system for automotive vehicles is provided which is designed to minimize the kickback produced in a brake master cylinder and transmitted to a vehicle operator through a brake pedal during braking control or to inform the vehicle operator of generation of the kickback in advance for alleviating the discomfort due to the kickback. The braking system includes a pressure regulating valve which restricts transmission of a pressure variation to the master cylinder from a hydraulic braking circuit during the braking control to reduce the kickback. The braking system may alternatively include a pressure-reducing valve which reduces the hydraulic pressure within the brake master cylinder to decrease a hydraulic reaction force against the pedal effort provided by the vehicle operator when a wheel is approaching or has reached a road-tire adhesion limit for warning the vehicle operator of generation of the kickback in advance.