Regenerative braking/anti-lock braking control system

A vehicle comprising:

• a drivetrain having a transmission, a differential, an input shaft to the differential, first and second output shafts from the differential, wherein an output of the transmission is connected to the input shaft and the first and second output shafts are asymmetrical;
• an electric machine secured to an input of the transmission and configured to recharge a battery during regenerative braking;
• first and second wheels secured to the first and second output shafts, respectively;
• first and second friction brakes configured to apply torque to the first and second wheels, respectively, to slow the vehicle;
• and
• a controller programmed to, in response to and during an anti-locking braking event,
• generate a first signal indicative of a braking torque demand at the first wheel based on a difference between a desired wheel slip ratio and an actual wheel slip ratio of the first wheel,
• generate a second signal indicative of a braking torque demand at the second wheel based on a difference between a desired wheel slip ratio and an actual wheel slip ratio of the second wheel,
• adjust a regenerative braking torque of the electric machine based on a product of the first signal and a regenerative braking weighting coefficient to maintain or drive actual wheel slip at or toward the desired wheel slip, wherein the regenerative braking weighting coefficient is based on a ratio between a maximum braking torque of the electric machine and the total torque demand,
• adjust a first friction braking torque of the first friction brake based on a product of the first signal and a friction braking weighting coefficient to maintain or drive actual wheel slip at or toward the desired wheel slip, and
• adjust a second friction braking torque of the second friction brake based on the second signal and transfer functions that represent the dynamics of the first and second output shafts.

A vehicle comprising:

• a drivetrain having a driveshaft and first and second half shafts, wherein the first and second half shaft are asymmetrical;
• first and second wheels secured to the first and second half shafts, respectively;
• an electric machine connected to the driveshaft;
• first and second friction brakes connected to the first and second wheels, respectively;
• and
• a controller programmed to, in response to and during an anti-locking braking event,
• generate a first signal indicative of a braking torque demand at the first wheel based on a difference between a desired wheel slip ratio and an actual wheel slip ratio of the first wheel,
• generate a second signal indicative of a braking torque demand at the second wheel based on a difference between a desired wheel slip ratio and an actual wheel slip ratio of the second wheel,
• determine a regenerative braking weighting coefficient based on a ratio between a maximum braking torque of the electric machine and a braking torque threshold that corresponds with the wheels becoming locked,
• determine a friction braking weighting coefficient based on the regenerative braking weighting coefficient,
• adjust a regenerative braking torque of the electric machine based the first signal and the regenerative braking weighting coefficient during the anti-lock braking event to maintain or drive actual wheel slip at or toward the desired wheel slip,
• adjust a first friction braking torque of the first friction brake based on the first signal and the friction braking weighting coefficient weighting coefficient, and
• adjust a second friction braking torque of the second friction brake based on the second signal and transfer functions that represent the dynamics of the first and second half shafts.