Blended vehicle brake systems and control logic with friction brake burnish learning and compensation

A non-transient, computer-readable medium storing instructions executable by one or more vehicle controllers of a motor vehicle with a blended brake system, the blended brake system including a regenerative (regen) brake system and a friction brake system operable to decelerate one or more road wheels of the motor vehicle, the instructions, when executed, causing the one or more vehicle controllers to perform operations comprising:

• receiving, from a user input device or a vehicle control module of the motor vehicle, a vehicle brake command with a total brake torque request for the motor vehicle;
• determining, using the total brake torque request, a regen brake torque for the regen brake system and a friction brake torque for the friction brake system;
• estimating, using the friction brake torque and an estimated temperature of a rotating friction brake element, a temperature-dependent friction coefficient;
• determining an estimated burnish state of the friction brake system including calculating a burnish energy analogue as a function of a current vehicle speed of the motor vehicle, a predefined runtime timestep, and the friction brake torque of the friction brake system;
• estimating, using the friction brake torque and the estimated burnish state of the friction brake system, a burnish-dependent friction coefficient;
• determining a modified brake pressure coefficient using the temperature-dependent friction coefficient and the burnish-dependent friction coefficient;
• determining a modified friction brake torque using the modified brake pressure coefficient;
• commanding the friction brake system to apply the modified friction brake torque to the one or more road wheels of the motor vehicle;
• and
• commanding the regen brake system to apply the regen brake torque to the one or more road wheels of the motor vehicle.

A motor vehicle, comprising:

• a vehicle body;
• a plurality of road wheels attached to the vehicle body;
• a prime mover attached to the vehicle body and configured to drive at least one of the road wheels to thereby propel the motor vehicle;
• a blended brake system attached to the vehicle body and including a regenerative (regen) brake system and a friction brake system both operable to decelerate one or more of the road wheels responsive to brake commands from a user input device or a vehicle control module;
• and
• a vehicle controller programmed to:
• receive, from the user input device or the vehicle control module, a vehicle brake command with a total brake torque request for the motor vehicle;
• determine, using the total brake torque request, a regen brake torque for the regen brake system and a friction brake torque for the friction brake system;
• determine an estimated burnish state of the friction brake system including calculating a burnish energy analogue as a function of a current vehicle speed of the motor vehicle, a predefined runtime timestep, and the friction brake torque of the friction brake system;
• estimate, using the friction brake torque and the estimated burnish state of the friction brake system, a burnish-dependent friction coefficient;
• determine a modified brake pressure coefficient using the burnish-dependent friction coefficient;
• determine a modified friction brake torque using the modified brake pressure coefficient;
• and
• command the friction brake system to apply the modified friction brake torque to the one or more road wheels of the motor vehicle.