Abstract: A method of assisting deceleration during a stop of a motor vehicle having a drivetrain including a traction motor, a road wheel operatively connected to the drivetrain, a friction brake configured to decelerate the road wheel, and an electronic controller includes detecting, via the electronic controller, a request to stop the vehicle. The method also includes commanding the traction motor to provide regenerative braking in response to the request to stop the vehicle. The method additionally includes determining a current vehicle operating state. The method also includes determining an amount of brake drag torque to be generated by the friction brake based on the current vehicle operating state. The method further includes commanding an application of the determined amount of the brake drag torque in parallel with the regenerative braking, thereby operating the friction brake as a mechanical drivetrain damper while assisting the regenerative braking to stop the motor vehicle.

Abstract: A method of operating a vehicle includes a vehicle controller receiving an operator-input vehicle control command with an associated torque request, and identifying any propulsion actuator constraints that limit a brake torque capacity available from the vehicle powertrain. Using the propulsion actuator constraint(s) and torque request, the controller determines a propulsion brake torque distribution for the vehicle's road wheels and a maximum brake torque capacity for the powertrain actuator(s). A first brake torque request is determined using the propulsion brake torque distribution and a vehicle control mode of the powertrain system, and a second brake torque request is determined using the maximum brake torque capacity and the vehicle control mode. A friction brake torque command is determined by arbitrating between the first and second brake torque requests.

Abstract: A method detects unintended acceleration of a motor vehicle during a closed-loop speed control mode by determining external forces on the vehicle via a controller, and then calculating a desired acceleration using a measured vehicle speed and the external forces. The method includes determining an actual acceleration of the vehicle, including filtering a speed signal as a first actual acceleration value and/or measuring a second actual acceleration value using an inertial measurement unit (IMU). During the speed control mode, the method includes calculating an acceleration delta value as a difference between the desired acceleration and the actual acceleration, and then using the acceleration delta value to detect the unintended acceleration during the speed control mode. A powertrain system for the motor vehicle, e.g., an electric vehicle, includes the controller and one or more torque generating devices coupled to road wheels of the vehicle.

Abstract: A method of operating a vehicle includes a vehicle controller receiving a driver acceleration/deceleration command for the vehicle's powertrain and determining a torque request corresponding to the driver's acceleration command. The controller shapes the torque request and determines compensated and uncompensated accelerations from the shaped torque request. The compensated acceleration is based on an estimated road grade and an estimated vehicle mass, whereas the uncompensated acceleration is based on a zero road grade and a nominal vehicle mass. A final speed horizon profile is calculated as: a speed-control speed profile based on the uncompensated acceleration if the vehicle's speed is below a preset low vehicle speed; or a torque-control speed profile based on a blend of the compensated and uncompensated accelerations if the vehicle speed exceeds the preset low vehicle speed. The controller commands the powertrain to output a requested axle torque based on the final speed horizon profile.

Abstract: A method of assisting deceleration during a stop of a motor vehicle having a drivetrain including a traction motor, a road wheel operatively connected to the drivetrain, a friction brake configured to decelerate the road wheel, and an electronic controller includes detecting, via the electronic controller, a request to stop the vehicle. The method also includes commanding the traction motor to provide regenerative braking in response to the request to stop the vehicle. The method additionally includes determining a current vehicle operating state. The method also includes determining an amount of brake drag torque to be generated by the friction brake based on the current vehicle operating state. The method further includes commanding an application of the determined amount of the brake drag torque in parallel with the regenerative braking, thereby operating the friction brake as a mechanical drivetrain damper while assisting the regenerative braking to stop the motor vehicle.

Abstract: A method detects unintended acceleration of a motor vehicle during a closed-loop speed control mode by determining external forces on the vehicle via a controller, and then calculating a desired acceleration using a measured vehicle speed and the external forces. The method includes determining an actual acceleration of the vehicle, including filtering a speed signal as a first actual acceleration value and/or measuring a second actual acceleration value using an inertial measurement unit (IMU). During the speed control mode, the method includes calculating an acceleration delta value as a difference between the desired acceleration and the actual acceleration, and then using the acceleration delta value to detect the unintended acceleration during the speed control mode. A powertrain system for the motor vehicle, e.g., an electric vehicle, includes the controller and one or more torque generating devices coupled to road wheels of the vehicle.

Abstract: A method of operating a vehicle includes a vehicle controller receiving an operator-input vehicle control command with an associated torque request, and identifying any propulsion actuator constraints that limit a brake torque capacity available from the vehicle powertrain. Using the propulsion actuator constraint(s) and torque request, the controller determines a propulsion brake torque distribution for the vehicle's road wheels and a maximum brake torque capacity for the powertrain actuator(s). A first brake torque request is determined using the propulsion brake torque distribution and a vehicle control mode of the powertrain system, and a second brake torque request is determined using the maximum brake torque capacity and the vehicle control mode. A friction brake torque command is determined by arbitrating between the first and second brake torque requests.

Abstract: A method of operating a vehicle includes a vehicle controller receiving a driver acceleration/deceleration command for the vehicle's powertrain and determining a torque request corresponding to the driver's acceleration command. The controller shapes the torque request and determines compensated and uncompensated accelerations from the shaped torque request. The compensated acceleration is based on an estimated road grade and an estimated vehicle mass, whereas the uncompensated acceleration is based on a zero road grade and a nominal vehicle mass. A final speed horizon profile is calculated as: a speed-control speed profile based on the uncompensated acceleration if the vehicle's speed is below a preset low vehicle speed; or a torque-control speed profile based on a blend of the compensated and uncompensated accelerations if the vehicle speed exceeds the preset low vehicle speed. The controller commands the powertrain to output a requested axle torque based on the final speed horizon profile.