Anti-skid control system

An anti-skid control system for a vehicle which is provided with wheels including driving wheels, comprising:

• wheel velocity detectors each of which detects a wheel velocity of a corresponding driving wheel;
• braking operation detecting means for detecting a braking operation on the basis of the wheel velocity at the time when the braking operation is started;
• estimated vehicle speed calculation means for calculating an estimated vehicle speed;
• braking force control means for controlling the braking force of each of the wheels while the braking operation detecting means detects a braking operation in such a manner that the braking force is set to be controlled in accordance with the magnitude of the braking operation and is set to be decreased when the wheel velocity is less than the estimated vehicle speed for the prevention of the slip of each of the wheels;
• acceleration slip estimating means for estimating an acceleration slip when a decline ratio of the wheel velocity continues to exceed a value for a first period of time while the braking operation detection means fails to detect a braking operation;
• acceleration slip judging means for judging the occurrence of an acceleration slip when the estimated vehicle speed continues to exceed the wheel velocity for a second period of time after the detection of a braking operation by the braking operation detecting means upon estimation of the acceleration slip;
• and
• estimated vehicle speed revising means for decreasing the estimated vehicle speed when an acceleration slip is judged to have occurred by the acceleration slip judging means.

A method for controlling an anti-skid control system of a vehicle which is provided with wheels including driving wheels, the method comprising the steps of:

• estimating an acceleration slip when a decline ratio of a wheel velocity is large and a braking operation is not established;
• controlling the braking force in accordance with the magnitude of a braking operation when the braking operation is executed;
• calculating an estimated vehicle speed on the basis of the wheel velocity at the time when the braking operation is started;
• decreasing the braking force when the wheel velocity is less than the estimated vehicle speed;
• judging whether acceleration slip has occurred when the acceleration slip is estimated and when the estimated vehicle speed continues to exceed the wheel velocity after the braking operation;
• and
• increasing the braking force when an acceleration slip is judged to have occurred.