Dynamic torque filling

1 . A system for controlling torque in a vehicle, comprising:

a controller connected to a first propulsion system and a second propulsion system of the vehicle, the first propulsion system including a combustion engine configured to drive a primary axle, the second propulsion system including an electric motor configured to drive a secondary axle, wherein the first propulsion system and the primary axle are mechanically independent from the second propulsion system and the secondary axle, the controller configured to perform a method including:

receiving a primary axle torque request;

converting the primary axle torque request to a shaped torque request, the shaped torque request prescribing a desired change in a primary axle torque to achieve a requested torque;

determining a time period based on a time at which the shaped torque request approaches the primary axle torque request; and

during the time period:

estimating a first amount of torque applied to the primary axle in response to the primary axle torque request;

determining a difference between the first amount of torque applied to the primary axle and the primary axle torque request; and

based on the difference exceeding a selected threshold, calculating a dynamic fill torque and applying a second amount of torque to the secondary axle via the electric motor according to the calculated dynamic fill torque.

2 . The system of claim 1 , wherein the method includes, during the applying the second amount of torque, performing:

monitoring the primary axle torque request and determining a first amount of time during which the primary axle torque request is non-zero;

determining a second amount of time that the first amount of torque is applied to the primary axle;

determining a third amount of time that the secondary amount of torque is applied to the secondary axle;

calculating a sum of the second amount of time and the third amount of time; and

based on first amount of time being greater than the sum, removing the second amount of torque from the secondary axle.

3 . The system of claim 1 , wherein the dynamic fill torque is configured as a dynamic fill torque profile, the dynamic fill torque profile calculated by limiting the shaped torque request based on the difference.

4 . The system of claim 1 , wherein the primary axle torque request is selected from a torque request provided by a control system, and an intended torque request, the intended torque request based on driver inputs applied to an acceleration pedal, the driver inputs including at least one of a position of the acceleration pedal and a movement of the acceleration pedal.

5 . The system of claim 4 , wherein the difference is between the estimated first amount of torque and the intended torque request.

6 . The system of claim 1 , wherein the controller is configured to initiate the method based on at least one activation criteria, the activation criteria including a minimum displacement of a pedal, a minimum magnitude of the first amount of torque being applied to the primary axle, and a minimum rate of change of the first amount of torque.

7 . The system of claim 1 , wherein the controller is configured to limit a magnitude and/or rate of the second amount of torque.

8 . The system of claim 7 , wherein the method includes limiting the second amount of torque based on at least one of: a state of charge of a battery assembly connected to the electric motor, a lateral acceleration, a vehicle operating mode and a capacity of the secondary axle.

9 . The system of claim 1 , wherein the vehicle includes a battery assembly connected to the electric motor, and the controller is configured to cease applying the second amount of torque based on a state of charge of the battery assembly being below a state of charge threshold.

10 . The system of claim 1 , wherein the method includes calculating a total torque amount by summing the dynamic fill torque and the first amount of torque, and eliminating application of the second amount of torque based on the primary axle torque request exceeding the total torque amount for a selected time period.

11 . A method of controlling torque in a vehicle, comprising:

detecting a primary torque request for applying torque to a primary axle of the vehicle, the vehicle including a first propulsion system and a second propulsion system, the first propulsion system including a combustion engine configured to drive a primary axle, the second propulsion system including an electric motor configured to drive a secondary axle, wherein the first propulsion system and the primary axle are mechanically independent from the second propulsion system and the secondary axle;

converting the primary axle torque request to a shaped torque request, the shaped torque request prescribing a desired change in a primary axle torque to achieve a requested torque;

determining a time period based on a time at which the shaped torque request approaches the primary axle torque request; and

during the time period:

estimating a first amount of torque applied to the primary axle in response to the primary axle torque request;

determining a difference between the first amount of torque applied to the primary axle and the primary axle torque request; and

based on the difference exceeding a selected threshold, calculating a dynamic fill torque and applying a second amount of torque to the secondary axle via the electric motor according to the calculated dynamic fill torque.

12 . The method of claim 11 , further comprising, during the applying the second amount of torque, performing:

monitoring the primary axle torque request and determining a first amount of time during which the primary axle torque request is non-zero;

determining a second amount of time that the first amount of torque is applied to the primary axle;

determining a third amount of time that the secondary amount of torque is applied to the secondary axle;

calculating a sum of the second amount of time and the third amount of time; and

based on first amount of time being greater than the sum, removing the second amount of torque from the secondary axle.

13 . The method of claim 11 , wherein the dynamic fill torque is configured as a dynamic fill torque profile, the dynamic fill torque profile calculated by limiting the shaped torque request based on the difference.

14 . The method of claim 11 , wherein the primary axle torque request is selected from a torque request provided by a control system, and an intended torque request, the intended torque request based on driver inputs applied to an acceleration pedal, the driver inputs including at least one of a position of the acceleration pedal and a movement of the acceleration pedal, and wherein the difference is between the estimated first amount of torque and the intended torque request.

15 . The method of claim 11 , wherein the method is initiated based on at least one activation criteria, the activation criteria including a minimum displacement of a pedal, a minimum magnitude of the first amount of torque being applied to the primary axle, and a minimum rate of change of the first amount of torque.

16 . The method of claim 11 , further comprising limiting the second amount of torque based on at least one of: a state of charge of a battery assembly connected to the electric motor, a lateral acceleration, a vehicle operating mode and a capacity of the secondary axle.

17 . A vehicle system comprising:

a first propulsion system including a combustion engine configured to drive a primary axle of a vehicle;

a second propulsion system including an electric motor configured to drive a secondary axle, wherein the first propulsion system and the primary axle are mechanically independent from the second propulsion system and the secondary axle; and

a processing device for executing computer readable instructions from a memory, the computer readable instructions controlling the processing device to perform a method including:

detecting a primary torque request for applying torque to the primary axle;

converting the primary axle torque request to a shaped torque request, the shaped torque request prescribing a desired change in a primary axle torque to achieve a requested torque;

determining a time period based on a time at which the shaped torque request approaches the primary axle torque request; and

during the time period:

estimating a first amount of torque applied to the primary axle in response to the primary axle torque request;

determining a difference between the first amount of torque applied to the primary axle and the primary axle torque request; and

based on the difference exceeding a selected threshold, calculating a dynamic fill torque and applying a second amount of torque to the secondary axle via the electric motor according to the calculated dynamic fill torque.

18 . The vehicle system of claim 17 , wherein the dynamic fill torque is configured as a dynamic fill torque profile, the dynamic fill torque profile calculated by limiting the shaped torque request based on the difference.

19 . The vehicle system of claim 17 , wherein the primary axle torque request is selected from a torque request provided by a control system, and an intended torque request, the intended torque request based on driver inputs applied to an acceleration pedal, the driver inputs including at least one of a position of the acceleration pedal and a movement of the acceleration pedal, and wherein the difference is between the estimated first amount of torque and the intended torque request.

20 . The vehicle system of claim 17 , wherein the method is initiated based on at least one activation criteria, the activation criteria including a minimum displacement of a pedal, a minimum magnitude of the first amount of torque being applied to the primary axle, and a minimum rate of change of the first amount of torque.