Abstract: A system and a method for determining when to update a surface estimation value indicative of a condition of a roadway surface are provided. The method includes determining a front axle cornering force error value based on a predicted front axle cornering force value and a first front axle cornering force value. The method further includes determining a threshold yaw rate error value based on the front axle cornering force error value. The method further includes indicating that the surface estimation value is to be updated when a yaw rate error value is greater than the threshold yaw rate error value.

Abstract: A system and a method for determining when to update a surface estimation value indicative of a condition of a roadway surface are provided. The method includes determining a front axle cornering force error value based on a predicted front axle cornering force value and a first front axle cornering force value. The method further includes determining a threshold yaw rate error value based on the front axle cornering force error value. The method further includes indicating that the surface estimation value is to be updated when a yaw rate error value is greater than the threshold yaw rate error value.

Abstract: A method is directed to controlling a differential within an active antilock brake system. The method provides for receiving a secondary axle wheel speed, receiving a vehicle speed, determining a difference value between the vehicle speed and the secondary axle wheel speed, and activating the differential responsive to the difference value. The step of activating the differential responsive to the difference value may include steps for comparing the difference value to a threshold value and activating the differential based on the comparison.

Abstract: A method is directed to controlling a traction control system including a controllable center coupling and a controlled brake system. The method provides for receiving axle speed information, receiving a vehicle speed, determining at least one difference value between the vehicle speed and the axle speed information, and activating the controllable center coupling and the controlled brake system responsive to the difference values. The step of activating the controllable center coupling responsive to at least one of the difference values may include comparing the at least one difference value to at least one associated threshold value, and activating the controllable center coupling based on the comparison. The step of activating the controllable center coupling based on the comparison may include determining an engine torque request value based on the comparison, and engaging an engine with the controllable center coupling based on the engine torque request value.

Abstract: A method is directed to controlling a traction control system including a controllable center coupling and a controlled brake system. The method provides for receiving axle speed information, receiving a vehicle speed, determining at least one difference value between the vehicle speed and the axle speed information, and activating the controllable center coupling and the controlled brake system responsive to the difference values. The step of activating the controllable center coupling responsive to at least one of the difference values may include comparing the at least one difference value to at least one associated threshold value, and activating the controllable center coupling based on the comparison. The step of activating the controllable center coupling based on the comparison may include determining an engine torque request value based on the comparison, and engaging an engine with the controllable center coupling based on the engine torque request value.

Abstract: A method is directed to controlling a differential within an active antilock brake system. The method provides for receiving a secondary axle wheel speed, receiving a vehicle speed, determining a difference value between the vehicle speed and the secondary axle wheel speed, and activating the differential responsive to the difference value. The step of activating the differential responsive to the difference value may include steps for comparing the difference value to a threshold value and activating the differential based on the comparison.

Abstract: A variable power steering system for a motor vehicle is responsive to an activity signal from a vehicle stability enhancement (VSE) system and a lateral surface coefficient of friction estimator to modify steering assist in an amount dependent on the estimated surface coefficient when the vehicle stability enhancement system is active. The modification is phased in and out with slew limiting in steps also determined by the estimated lateral surface coefficient, with both the maximum modification and the step size varying inversely with lateral surface coefficient. The system preferably determines offset current values for the VSE system and estimated lateral acceleration, as well as for any other vehicle traction limit handling systems such as anti-lock braking (ABS) or traction control (TCS) and chooses the greatest in magnitude as a road surface adaptation offset current for addition to a vehicle speed offset current to provide a total current signal for the modification.

Abstract: A variable power steering system for a motor vehicle is responsive to an activity signal from a vehicle stability enhancement (VSE) system and a lateral surface coefficient of friction estimator to modify steering assist in an amount dependent on the estimated surface coefficient when the vehicle stability enhancement system is active. The modification is phased in and out with slew limiting in steps also determined by the estimated lateral surface coefficient, with both the maximum modification and the step size varying inversely with lateral surface coefficient. The system preferably determines offset current values for the VSE system and estimated lateral acceleration, as well as for any other vehicle traction limit handling systems such as anti-lock braking (ABS) or traction control (TCS) and chooses the greatest in magnitude as a road surface adaptation offset current for addition to a vehicle speed offset current to provide a total current signal for the modification.

Abstract: A traction control for a motor vehicle derives a target delta velocity as the sum of a longitudinal velocity of the vehicle and a target delta velocity derived from one or more of a longitudinal acceleration, a lateral acceleration and a turn curvature. The vehicle has a vehicle stability enhancement system of the type becoming active when a vehicle yaw rate error is sensed for providing braking control of individual wheels of the motor vehicle to reduce the vehicle yaw rate error below a predetermined value. In response to activity of the vehicle stability enhancement system in reducing a vehicle yaw rate error, the target delta velocity, and thus the target velocity, is bounding between a maximum target velocity value and a minimum target velocity value, at least one of which is derived from an estimated coefficient of friction between the vehicle drive wheels and the drive surface.