Feed-forward engine idle speed control

1. A vehicle comprising:

an engine having a crankshaft and an engine idle speed;

an accelerator pedal, the depression of which generates a throttle request signal;

a transmission having an input member and an input clutch, wherein the input clutch selectively connects the crankshaft to the input member during a creep maneuver of the vehicle;

an engine control module (ECM) in communication with the engine; and

a transmission control module (TCM) in communication with the ECM and with the transmission, wherein:

the TCM is programmed to identify a target clutch torque of the input clutch during the creep maneuver of the vehicle, as an engine torque value that results in a threshold creep speed, and to communicate the identified target clutch torque to the ECM;

the ECM is programmed to maintain the engine idle speed at a threshold level through a duration of the creep maneuver using the identified target clutch torque as a feed-forward engine idle speed control term; and

the TCM is further programmed to detect a requested launch maneuver of the vehicle via the throttle request signal, and to increase the target clutch torque at a calibrated rate in response to the detected requested launch maneuver, wherein the calibrated rate results in a speed of the engine that exceeds the threshold creep speed.

2. The vehicle of claim 1 , wherein the transmission is a dual clutch transmission having, as the input clutch, a first input clutch and a second input clutch.

3. The vehicle of claim 1 , further comprising a brake pedal, the depression of which generates a braking signal, wherein the ECM is programmed to detect a threshold braking event via the braking signal, and to decrease the target clutch torque at a calibrated rate in response to the detected threshold braking event.

4. The vehicle of claim 1 , wherein the calibrated rate includes multiple calibrated rates, each of which corresponds to a different threshold throttle request.

5. The vehicle of claim 4 , wherein the TCM is configured to calculate an amount of slip across the input clutch during the detected launch maneuver, and wherein one of the multiple calibrated rates corresponds to a calculated amount of slip across the input clutch that exceeds a calibrated slip threshold.

6. The vehicle of claim 5 , wherein the TCM decreases the target clutch torque at another of the multiple calibrated rates upon detection by the ECM of a throttle tip-out event.

7. A system for a vehicle having an accelerator pedal operable for generating a throttle request signal, an engine responsive to the throttle request signal, and an engine control module (ECM), the system comprising:

a transmission having an input member and an input clutch that selectively connects a crankshaft of the engine to the input member; and

a transmission control module (TCM) in communication with the ECM and with the input clutch, wherein the TCM is programmed to identify a target clutch torque of the input clutch as an engine torque value that results in a threshold creep speed during a creep maneuver of the vehicle, and to communicate the identified target clutch torque to the ECM as a feed-forward engine idle speed control term, and wherein the TCM is further programmed to detect a requested launch maneuver of the vehicle using the throttle request signal to increase the target clutch torque at a calibrated rate in response to the detected requested launch maneuver, wherein the calibrated rate results in a speed of the engine that exceeds the threshold creep speed.

8. The system of claim 7 , wherein the transmission is a dual clutch transmission having, as the input clutch, a first input clutch and a second input clutch.

9. The system of claim 7 , wherein the vehicle includes a brake pedal, the depression of which generates a braking signal, and wherein the TCM is programmed to decrease the target clutch torque at a calibrated rate in response to the threshold braking signal exceeding a calibrated hard braking threshold.

10. The system of claim 9 , wherein the calibrated rate includes multiple calibrated rates, each of which corresponds to a different threshold throttle request.

11. The system of claim 10 , wherein the TCM is programmed to calculate an amount of slip across the input clutch during the requested launch maneuver, and wherein one of the multiple calibrated rates corresponds to a calculated amount of slip across the input clutch that exceeds a calibrated slip threshold.

12. The system of claim 11 , wherein the TCM is programmed to drop the target clutch torque at another of the multiple calibrated rates upon detection by the ECM of a throttle tip-out event.

13. A method for controlling idle speed of an engine in a vehicle, the method comprising:

identifying, via a transmission control module (TCM), a target clutch torque of an input clutch of the vehicle as an engine torque value that results in a threshold creep speed during a creep maneuver of the vehicle;

communicating the identified target clutch torque to an engine control module (ECM);

maintaining the idle speed of the engine at a threshold level, via the ECM, through a duration of the creep maneuver using the identified target clutch torque as a feed-forward engine idle speed control term;

detecting a throttle request signal from an accelerator pedal;

detecting a requested launch maneuver of the vehicle via processing of the throttle request signal by one of the TCM and ECM; and

increasing the target clutch torque at a calibrated rate in response to the detected requested launch maneuver, wherein the calibrated rate results in a speed of the engine that exceeds the threshold creep speed.

14. The method of claim 13 , further comprising:

generating a braking signal via depression of a brake pedal;

detecting a threshold braking event via processing of the braking signal by one of the TCM and ECM; and

decreasing the target clutch torque at a calibrated rate, via the TCM, in response to the detected threshold braking event.

15. The method of claim 14 , wherein the calibrated rate includes multiple calibrated rates each corresponding to a different throttle request.

16. The method of claim 15 , further comprising:

calculating an amount of slip across the input clutch during the requested launch maneuver; and

increasing the target clutch torque at one of the calibrated rates corresponding to a calculated amount of slip across the input clutch exceeding a calibrated threshold.

17. The method of claim 16 , further comprising:

detecting a throttle tip-out event via the ECM; and

decreasing the target clutch torque, via the TCM, at another of the multiple calibrated rates upon detection by the ECM of the throttle tip-out event.