Patent ID: 6079801
Filing Date: 2000-06-27
Classification: B60T

Abstract:
A method of operating an electrically actuated braking system of a motor vehicle, which comprises the following steps:measuring wheel speeds of individual wheels of a motor vehicle with wheel sensors;individually controlling electrical, continuously acting wheel brake actuators such that an independent brake pressure is applied to each wheel of the motor vehicle;carrying out the following calculation and control procedures in a control unit:calculating a wheel slip and a wheel acceleration for each wheel;storing a respective actual value of the brake pressure in case of an upward transgression of a predefined first threshold value for one of the wheel slip and the wheel acceleration;forming a quotient of the stored actual value and a pressure value that is characteristic of the motor vehicle at a coefficient of friction .mu.=1 for the respective wheel, and estimating a first coefficient of friction;carrying out a brake-pressure closed-loop control operation to prevent locking at the individual wheels with reference to the estimated coefficient of friction in accordance with a predefined algorithm;clearing the first coefficient of friction in case of a downward transgression of a second threshold value for one of the wheel slip and the wheel acceleration, and replacing the first coefficient of friction with a new estimated coefficient of friction that can be increased up to a value for a dry underlying surface; andusing the stored brake pressure as a setpoint value for a brake-pressure closed-loop control operation to prevent locking.