Diagnostic and control method for a vehicle system

1. A method for operation of a vehicle system with an electric machine, comprising:

at a diagnostic controller independent from a driveline controller, respectively, determining an input device state and an electric machine torque;

determining a fault condition of a vehicle component based on the input device state and the electric machine torque; and

in response to determining the fault condition, triggering a fault state of the vehicle component and controlling the vehicle component in a fault mode;

wherein controlling the vehicle component in the fault mode includes operating the diagnostic controller to override a nominal control command sent from the driveline controller to the vehicle component; and

wherein the diagnostic controller and the driveline controller are not in electronic communication with one another.

2. The method of claim 1 , wherein the diagnostic controller and the driveline controller are positioned in separate enclosures.

3. The method of claim 1 , further comprising determining a gearbox clutch condition prior to determining the fault condition and wherein the fault condition is determined based on the gearbox clutch condition.

4. The method of claim 1 , wherein:

the input device state is a power request; and

the method further comprises:

determining a predicted wheel torque based on the electric machine torque; and

determining the fault condition includes determining that the fault condition is occurring when the predicted wheel torque is greater than a threshold value and the power request is less than a threshold value.

5. The method of claim 1 , wherein:

the input device state is a gear selector positon; and

the method further comprises:

determining a predicted wheel torque based on the electric machine torque; and

determining the fault condition includes determining that the fault condition is occurring when the predicted wheel torque is greater than a threshold value and is in a direction that is opposite than a direction selected by the gear selector.

6. The method of claim 1 , wherein the vehicle component is a gearbox that includes one or more clutches and wherein controlling the gearbox includes opening the one or more clutches.

7. The method of claim 1 , wherein the vehicle component is an inverter and wherein controlling the inverter in the fault mode includes decreasing a flow of power from the inverter to the electric machine.

8. The method of claim 1 , wherein the step of determining the fault condition is determined while a vehicle speed is less than a threshold value and the method further comprises inhibiting the determination of the fault condition when the vehicle speed is greater than the threshold value.

9. The method of claim 1 , wherein the fault state is triggered when the fault condition persists for a duration greater than a threshold value.

10. A vehicle system, comprising:

a diagnostic controller in electronic communication with a mechanical vehicle component and including:

instructions that, when executed, cause the diagnostic controller to:

determine an input device state and an electric machine torque; and

determine the occurrence of a fault condition based on the input device state and the electric machine torque; and

instructions that, when the fault condition is triggered, cause the diagnostic controller to:

control the mechanical vehicle component in a fault state; and

override a nominal control command sent from a driveline controller to the mechanical vehicle component;

wherein the diagnostic controller and the driveline controller are not in electronic communication with one another.

11. The vehicle system of claim 10 , wherein:

the input device state is a power request from a pedal; and

the occurrence of the fault condition is determined when a wheel torque derived from the electric machine torque is greater than a threshold value and the power request is less than a threshold value.

12. The vehicle system of claim 10 , wherein:

the input device state is a position of a gear selector;

the occurrence of the fault condition is determined when a wheel speed is in a direction opposite than a direction requested by the gear selector; and

the wheel speed is derived from the electric machine torque.

13. The vehicle system of claim 10 , wherein the fault condition is triggered when a vehicle speed is less than a threshold value and the fault state exceeds a threshold duration.

14. The vehicle system of claim 10 , wherein the mechanical vehicle component is an inverter, an electric machine, or a gearbox that includes one or more clutches.

15. The vehicle system of claim 14 , wherein when the mechanical vehicle component is the inverter and wherein controlling the inverter in the fault state includes decreasing a flow of power from the inverter to the electric machine.

16. The vehicle system of claim 14 , wherein when the mechanical vehicle component is the gearbox and wherein controlling the gearbox includes opening the one or more clutches.

17. A method for operation of a vehicle system with an electric machine, comprising:

operating a diagnostic processing unit in a diagnostic controller to:

determine an electric machine torque;

derive a wheel torque from the electric machine torque; and

responsive to the wheel torque exceeding a threshold value, trigger a fault condition corresponding to one of an inverter, electric machine, or gearbox and overriding a nominal control command sent from a driveline processing unit in a driveline controller to one of the inverter, electric machine, or gearbox;

wherein the diagnostic controller and the driveline controller are not in electronic communication with one another.

18. The method of claim 17 , wherein the fault condition is triggered when a vehicle speed is less than a threshold value.

19. The method of claim 17 , wherein the fault condition is a condition where wheel direction is opposite of a requested wheel direction.