CONTROL SYSTEM FOR BRAKE-STEER ASSISTED PARKING AND METHOD THEREFOR

• US 20050236894A1
• Filed: 03/18/2004
• Published: 10/27/2005
• Est. Priority Date: 03/18/2004
• Status: Active Grant

• 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.
• Granted Patent: US 7,229,139 B2
• Time in Patent Office: Days
• US Class Current: 303/139
• 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.

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 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 wherein the first boost curve is different than the second boost curve.

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

5. A method as recited in claim 3 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.

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

7. A method as recited in claim 3 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.

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

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

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

11. 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.

12. 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.

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

14. A method as recited in claim 12 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.

15. A method as recited in claim 12 wherein the first boost curve comprises a non-linear-boost curve.

16. A method as recited in claim 12 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.

17. A method as recited in claim 12 wherein the second boost curve comprises a non-linear-boost curve.

18. A method as recited in claim 12 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.

19. A method as recited in claim 12 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.

20. A method as recited in claim 12 wherein detecting a parking mode comprises detecting a parking mode in response to a vehicle speed.

21. A method as recited in claim 12 wherein detecting a parking mode comprises detecting a parking mode in response to a steering wheel angle.

22. A method as recited in claim 12 wherein detecting a parking mode comprises detecting a parking mode in response to a vehicle speed and a steering angle.

23. A method as recited in claim 12 wherein detecting a parking mode comprises detecting a parking mode in response to a driver-actuated switch.

24. A method as recited in claim 12 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.

25. A method as recited in claim 12 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.

26. A method as recited in claim 12 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.

27. A method as recited in claim 12 wherein applying brake-steer comprises applying at brake-steer as a function of an anti-lock brake system.

28. A method as recited in claim 12 wherein applying brake-steer comprises applying brake-steer as a function of a traction control system.

29. 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; and

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.

30. A method as recited in claim 29 further comprising 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.

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

32. A method as recited in claim 29 wherein detecting a parking mode comprises detecting a parking mode in response to a steering wheel angle.

33. A method as recited in claim 29 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.

34. A method as recited in claim 29 wherein detecting a parking mode comprises activation of a switch mechanism.

35. A method as recited in claim 29 wherein applying a second positive torque comprises applying the second positive torque as a function of a traction control system.

36. A method as recited in claim 29 further comprising switching from a 4×

4 mode into a 4×

2 mode when applying the second positive torque.

37. A method as recited in claim 29 wherein determining a parking mode comprises determining a parking mode in response to a steering system pressure.

38. A method of enhancing the turning ability of a vehicle having a steering mechanism comprising:

determining a driver selectable mode;

generating a steering enhance signal in response to the driver selectable mode; and

actuating at least one brake on one side of the vehicle in response to said steering enhance signal to enhance the turning radius achieved by the steering mechanism.

39. A method as recited in claim 38 wherein determining a driver selectable mode comprises determining a driver selectable mode in response to a switch mechanism.

40. A method as recited in claim 38 wherein actuating comprises actuating a first brake.

41. A method as recited in claim 38 wherein actuating comprises actuating a first brake and a second brake.

42. A method as recited in claim 38 wherein actuating comprises actuating a first brake at a first wheel and further comprising applying a positive engine torque at a second wheel.

43. A method as recited in claim 38 wherein activating a least one brake comprises activating at least one brake in response to an anti-lock brake system.

44. 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.

45. A method as recited in claim 44 wherein applying brake-steer comprises proportioning front wheel and rear wheel brakes based on the transfer case mode.

46. A method as recited in claim 44 wherein detecting a parking mode comprises detecting a parking mode in response to a vehicle speed.

47. A method as recited in claim 44 wherein detecting a parking mode comprises detecting a parking mode in response to a steering wheel angle.

48. A method as recited in claim 44 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.

49. A method as recited in claim 44 wherein detecting a parking mode comprises detecting a parking mode in response to a driver-actuated switch.

50. A method as recited in claim 44 wherein applying brake-steer comprises applying an increased drive torque to a second wheel relative to a first wheel.

51. A method as recited in claim 44 wherein applying brake-steer comprises applying brake-steer to a front wheel.

52. A method as recited in claim 44 wherein applying brake-steer comprise proportioning brake-steer between a front wheel and a rear wheel.

53. A vehicle comprising:

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 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.

54. A vehicle as recited in claim 53 further comprising a traction control system, wherein the first positive torque is a function of the traction control system.

55. A vehicle as recited in claim 53 wherein the means to determine a parking mode comprises detecting a parking mode in response to a vehicle speed.

56. A vehicle as recited in claim 53 the means to determine a parking mode comprises detecting a parking mode in response to a steering wheel angle.

57. A vehicle as recited in claim 53 wherein the means to determine a parking mode comprises detecting a parking mode in response to a vehicle speed and a steering angle.

58. A vehicle as recited in claim 53 wherein the means to determine a parking mode comprises detecting a parking mode in response to a driver-actuated switch.

59. A vehicle as recited in claim 53 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.

60. A method as recited in claim 53 wherein the vehicle comprises an open differential or a limited slip differential.

61. A vehicle as recited in claim 53 wherein the means to determine a parking mode comprises a steering system pressure sensor.