METHOD AND APPARATUS TO CONTROL VEHICLE OPERATION ON A GRADE

A vehicle system including a propulsion system coupled to a drive wheel and a friction brake configured to apply braking torque to a vehicle wheel is described. Operation thereof includes an instruction set that is executable to monitor vehicle speed, vehicle grade, and an operator braking request, and execute instructions upon achieving a vehicle speed that is less than a threshold speed. The instructions include controlling, via the friction brake, the braking torque to achieve a desired vehicle speed, and determining an operator acceleration request and the vehicle grade. The controller determines a minimum vehicle grade-based operator acceleration request, and releases the friction brake only when the operator acceleration request is greater than the minimum vehicle grade-based operator acceleration request.