Control system for brake-steer assisted parking and method therefor

• US 7,229,139 B2
• Filed: 03/18/2004
• Issued: 06/12/2007
• Est. Priority Date: 03/18/2004
• Status: Expired due to Fees

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Lu, Jianbo, Offerle, Timothy G., Tseng, Hongtei E., Rhode, Douglas S., Brown, Gregory P.
• Primary Examiner(s): Morris; Lesley D.
• Assistant Examiner(s): ARCE, MARLON ALEXANDER
• Application Number:
  US10/708,668
• Publication Number:
  US 20050236894A1
• Time in Patent Office: 1,181 Days
• Field of Search: 180/204, 180/6.24, 180/6.26, 180/249, 180/6.2, 303/146, 303/147, 303/191, 303/140
• US Class Current: 303/140
• CPC Class Codes: B60T 2201/10 Automatic or semi-automatic parking aid systems
• CPC Class Codes: B60T 2230/06 Tractor-trailer swaying
• CPC Class Codes: B60T 2260/02 Active Steering, Steer-by-Wire
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02
• CPC Class Codes: B60T 8/246 Change of direction
• CPC Class Codes: B60W 10/18 including control of braking systems
• CPC Class Codes: B60W 10/20 including control of steering systems
• CPC Class Codes: B60W 30/045 Improving turning performance
• CPC Class Codes: B62D 11/08 using brakes or clutches as main steering-effecting means
• CPC Class Codes: B62D 13/06 for backing a normally drawn trailer
• CPC Class Codes: B62D 15/027 Parking aids, e.g. instruction means
• CPC Class Codes: B62D 6/003 in order to control vehicle yaw movement, i.e. around a vertical axis B62D6/007 takes precedence
• CPC Class Codes: B62D 9/002 combined with means for differentially distributing power on the deflectable wheels during cornering

Abstract

A system and method of controlling an automotive vehicle includes determining a steering wheel angle, determining a steering wheel direction, determining a steering wheel angular rate and applying brake-steer as a function of steering wheel angle, steering wheel angular rate and steering wheel direction.

Claims

1. A method of controlling an automotive vehicle having a turning radius comprising:

determining a steering wheel angle;

determining a steering wheel direction;

determining a steering wheel angular rate and

applying brake-steer as a function of steering wheel angle, steering wheel angular rate and steering wheel direction, wherein the steering wheel direction comprises an increasing direction and a decreasing direction, wherein applying brake-steer comprises applying brake-steer using a first boost curve in a first direction and applying brake-steer using a second boost curve in a second direction, and wherein the first boost curve is different than the second boost curve.

2. A method as recited in claim 1 further comprising determining a vehicle speed and wherein applying brake-steer comprises applying brake-steer as a function of steering wheel angle, steering wheel rate, steering wheel direction and said vehicle speed.

3. A method as recited in claim 1 wherein the first boost curve comprises a non-linear-boost curve.

4. A method as recited in claim 1 wherein the first boost curve increases brake-steer at a first rate for a first period of time, increases brake-steer at a second rate for a second period of time, wherein the second rate is greater than the first rate, and increases brake-steer at third rate for a third period of time, wherein the third rate is less than the second rate.

5. A method as recited in claim 1 wherein the second boost curve comprises a non-linear-boost curve.

6. A method as recited in claim 1 wherein the second boost curve decreases brake-steer at a first rate for a first period of time and decreases brake-steer at a second rate for a second period of time, wherein the second rate is less than the first rate.

7. A method as recited in claim 1 wherein applying brake-steer reduces the turning radius of the vehicle.

8. A method as recited in claim 7 wherein applying brake-steer comprises applying at least one brake at a first wheel to reduce the vehicle turning radius.

9. A method as recited in claim 8 wherein applying brake-steer comprises applying an increased drive torque to a second wheel.

10. A method as recited in claim 1 further comprising detecting a parking mode, and applying brake-steer as a function of the parking mode, steering wheel angle, steering wheel angular rate and steering wheel direction.

11. A method of controlling an automotive vehicle comprising:

detecting a parking mode;

in the parking mode, when the steering wheel angle is increasing applying brake-steer using a first boost curve; and

when the steering wheel angle is decreasing applying brake-steer using a second boost curve different than the first boost curve.

12. A method as recited in claim 11 wherein applying brake-steer comprise a function of a steering wheel angle, a steering wheel angular rate and a steering wheel direction.

13. A method as recited in claim 11 further comprising determining a vehicle speed and wherein applying a brake-steer comprises applying brake-steer as a function of a steering wheel angle, a steering wheel rate, a steering wheel direction and a vehicle speed.

14. A method as recited in claim 11 wherein the first boost curve comprises a non-linear-boost curve.

15. A method as recited in claim 11 wherein the first boost curve increases brake-steer at a first rate for a first period of time, increases brake-steer at a second rate for a second period of time, wherein the second rate is greater than the first rate and increases brake-steer at third rate for a third period of time wherein the third rate is less than the second rate.

16. A method as recited in claim 11 wherein the second boost curve comprises a non-linear-boost curve.

17. A method as recited in claim 11 wherein the second boost curve decreases brake-steer at a first rate for a first period of time and decreases brake-steer at a second rate for a second period of time, wherein the second rate is less than the first rate.

18. A method as recited in claim 11 wherein applying brake-steer comprises applying at least one brake at a first wheel to reduce a vehicle turning radius of the vehicle;

and

simultaneously with the step of applying at least one brake, applying drive torque to a second wheel.

19. A method as recited in claim 11 wherein detecting a parking mode comprises detecting a parking mode in response to a vehicle speed.

20. A method as recited in claim 11 wherein detecting a parking mode comprises detecting a parking mode in response to a steering wheel angle.

21. A method as recited in claim 11 wherein detecting a parking mode comprises detecting a parking mode in response to a vehicle speed and a steering angle.

22. A method as recited in claim 11 wherein detecting a parking mode comprises detecting a parking mode in response to a driver-actuated switch.

23. A method as recited in claim 11 further comprising determining a surface mu, wherein applying brake-steer comprises applying brake-steer in response to the surface mu to reduce a vehicle turning radius.

24. A method as recited in claim 11 further comprising determining a vehicle load, wherein applying brake-steer comprises applying brake-steer at a first wheel in response to the vehicle load to reduce a vehicle turning radius.

25. A method as recited in claim 11 further comprising determining a throttle position, wherein applying brake-steer comprises applying brake-steer in response to the throttle position to reduce a vehicle turning radius.

26. A method as recited in claim 11 wherein applying brake-steer comprises applying at brake-steer as a function of an anti-lock brake system.

27. A method as recited in claim 11 wherein applying brake-steer comprises applying brake-steer as a function of a traction control system.

28. A method of controlling an automotive vehicle having a turning radius comprising:

detecting a parking mode;

in the parking mode, applying a first positive torque to a first driven wheel;

simultaneously with the step of applying a first positive torque, applying a second positive torque greater than the first positive torque to a second wheel so that the turning radius of the vehicle is reduced; and

determining a brake pressure request, and discontinuing the steps of applying a first positive torque and a second positive torque when said request is greater than a predetermined threshold.

29. A method as recited in claim 28 wherein detecting a parking mode comprises detecting a parking mode in response to a vehicle speed.

30. A method as recited in claim 28 wherein detecting a parking mode comprises detecting a parking mode in response to a steering wheel angle.

31. A method as recited in claim 28 wherein detecting a parking mode comprises detecting a parking mode in response to a map correlating vehicle speed and a steering wheel rate to a parking/non-parking condition.

32. A method as recited in claim 28 wherein detecting a parking mode comprises activation of a switch mechanism.

33. A method as recited in claim 28 wherein applying a second positive torque comprises applying the second positive torque as a function of a traction control system.

34. A method as recited in claim 28 further comprising switching from a 4×

4 mode into a 4×

2 mode when applying the second positive torque.

35. A method as recited in claim 28 wherein determining a parking mode comprises determining a parking mode in response to a steering system pressure.

36. A method of controlling an automotive vehicle having a turning radius comprising:

detecting a parking mode;

detecting a transfer case mode;

applying brake-steer in response to a parking mode and a transfer case mode, wherein applying brake-steer comprises proportioning front wheel and rear wheel brakes based on the transfer case mode.

37. A method as recited in claim 36 wherein detecting a parking mode comprises detecting a parking mode in response to a vehicle speed.

38. A method as recited in claim 36 wherein detecting a parking mode comprises detecting a parking mode in response to a steering wheel angle.

39. A method as recited in claim 36 wherein detecting a parking mode comprises detecting a parking mode in response to a map correlating vehicle speed and a steering wheel rate to a parking/non-parking condition.

40. A method as recited in claim 36 wherein detecting a parking mode comprises detecting a parking mode in response to a driver-actuated switch.

41. A method as recited in claim 36 wherein applying brake-steer further comprises applying an increased drive torque to a second wheel relative to a first wheel.

42. A method as recited in claim 36 wherein applying brake-steer further comprises applying brake-steer to a front wheel.

43. A vehicle comprising:

a traction control system;

means to determine a parking mode; and

a controller coupled to the means to determine a parking mode, said controller programmed to, in the parking mode, apply a first positive torque, as a function of said traction control system, to a first driven wheel and simultaneously with applying the first positive torque, apply a second positive torque greater than the first positive torque to a second wheel so that the turning radius of the vehicle is reduced.

44. A vehicle as recited in claim 43 wherein the means to determine a parking mode comprises detecting a parking mode in response to a vehicle speed.

45. A vehicle as recited in claim 43 the means to determine a parking mode comprises detecting a parking mode in response to a steering wheel angle.

46. A vehicle as recited in claim 43 wherein the means to determine a parking mode comprises detecting a parking mode in response to a vehicle speed and a steering angle.

47. A vehicle as recited in claim 43 wherein the means to determine a parking mode comprises detecting a parking mode in response to a driver-actuated switch.

48. A vehicle as recited in claim 43 further comprising a transfer case having a 4×

2 mode and a 4×

4 mode, said controller selecting 4×

2 mode when applying a second positive torque.

49. A method as recited in claim 43 wherein the vehicle comprises an open differential or a limited slip differential.

50. A vehicle as recited in claim 43 wherein the means to determine a parking mode comprises a steering system pressure sensor.