Stability control method and system for use when driving on a low-μ surface
View Patent ↗A system and a method for assisting a driver of a vehicle to turn the vehicle when driving during low-mu surface conditions. The vehicle has a steering system, a plurality of wheels and a brake system allowing individual braking of the respective wheels of the vehicle. The system comprises a controller arranged to detect if the vehicle accelerates after the brakes of the vehicle have been applied, and detect a driver command to turn the vehicle in either direction. If both detections are positive the controller is further arranged to release the brake force on a side of the vehicle opposite to the detected turning command direction.
1. A stability control system for a vehicle having a steering system, a plurality of wheels and a brake system, the system operative to:
detect forward acceleration of the vehicle after the brakes are applied; detect a driver command to turn the vehicle in a desired direction;
in response to the above two conditions, reduce brake force applied to wheels on a side of the vehicle opposite from the desired direction;
compare a vehicle velocity with a predetermined velocity threshold;
apply braking in a first manner to optimize velocity reduction if the vehicle velocity is
above the threshold; and
apply braking in a second manner to optimize vehicle control if the vehicle velocity is below the threshold.
2. The system of claim 1 wherein the controller is further operative to use the detected forward acceleration to determine a low coefficient-of-friction between a road surface and the wheels of the vehicle.
3. The system of claim 1 wherein the controller is further to use the detected forward acceleration to determine a downhill road gradient.
4. The system of claim 1 comprising wheel speed sensors and a vehicle accelerometer sending signals to the controller, the controller using the signals to detect the forward acceleration after the brakes are applied.
5. A vehicle stability control method comprising:
detecting a vehicle brake application; detecting a forward acceleration of the vehicle after the brake application; detecting a driver command to turn the vehicle in a desired direction;
reducing braking force on a wheel on a side of the vehicle opposite from the desired direction
comparing a vehicle velocity with a predetermined velocity threshold;
applying braking in a first manner to optimize velocity reduction if the vehicle velocity is
above the threshold; and
applying braking force in a second manner to optimize vehicle control if the vehicle velocity is below the threshold.
6. The method of claim 5 further comprising using the detected forward acceleration to determine a low coefficient-of-friction between a road surface and wheels of the vehicle.
7. The method of claim 5 further comprising using the detected forward acceleration to determine a downhill road gradient.
8. A stability control method for a vehicle comprising:
detecting a vehicle brake application;
detecting a forward acceleration of the vehicle after the brake application;
inferring from the above two detected conditions that the vehicle is driving on a surface having a low coefficient-of-friction and a downhill gradient;
comparing a vehicle velocity with a predetermined velocity threshold;
applying braking in a first manner to optimize velocity reduction if the vehicle velocity is above the threshold; and
applying braking force in a second manner to optimize vehicle control if the vehicle velocity is below the threshold.
9. The method of claim 8 further comprising:
detecting a driver command to turn the vehicle in a desired direction; and
reducing braking force on a wheel on a side of the vehicle opposite from the desired direction.