Abstract: A traction control for a motor vehicle responds to detection of a rough road surface so as to shift control away from propulsion power reduction and toward brake control to an over-spinning driven wheel when the rough road surface is detected. This better adapts the traction control to a road surface that may have a high coefficient of friction but produces intermittent loss of traction due to wheel hop or normal force fluctuations due to the rough road surface. The lower power reduction is obtained by increasing a target brake pressure used to derive a brake pressure error signal from which from which a power reduction command is derived. A delta target brake pressure may also be increased to provide a higher target velocity for the driven wheel propulsion.

Abstract: A traction control for a motor vehicle responds to detection of a rough road surface so as to shift control away from propulsion power reduction and toward brake control to an over-spinning driven wheel when the rough road surface is detected. This better adapts the traction control to a road surface that may have a high coefficient of friction but produces intermittent loss of traction due to wheel hop or normal force fluctuations due to the rough road surface. The lower power reduction is obtained by increasing a target brake pressure used to derive a brake pressure error signal from which from which a power reduction command is derived. A delta target brake pressure may also be increased to provide a higher target velocity for the driven wheel propulsion.

Abstract: A vehicle powertrain torque control provides an engine drag control mode of operation during periods of undesired engine drag induced wheel slip by modifying the torque of the vehicle engine in closed loop control to maintain a driven wheel speed at a predetermined target velocity lower than the vehicle speed by a target velocity difference providing as much engine braking as is consistent with a desired degree of lateral traction. The control derives a velocity error as the difference between the driven wheel speed and the target velocity and derives and delivers to the powertrain a torque command for reducing the velocity error. The torque control determines the engine drag control mode in response to the wheel speed sensors, preferably causing entry of the engine drag control mode when the driven wheel speed that is closest to the vehicle speed falls below the target velocity while powertrain delivered torque and throttle position are below predetermined values indicative of deceleration.