VEHICLE STABILITY CONTROL SYSTEM AND METHOD

• US 20120185142A1
• Filed: 03/29/2012
• Published: 07/19/2012
• Est. Priority Date: 10/30/2007
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: MEYERS, Joseph Carr, EISELE, Daniel Domek, BROWN, Todd Allen, XU, Li, SALIB, Albert Chenouda
• Granted Patent: US 8,682,560 B2
• Time in Patent Office: Days
• US Class Current: 701/70
• CPC Class Codes: B60T 2230/02 Side slip angle, attitude angle, floating angle, drift angle
• 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: B60W 10/04 including control of propulsion units
• 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 2050/0033 Single-track, 2D vehicle model, i.e. two-wheel bicycle model
• CPC Class Codes: B60W 30/045 Improving turning performance

Abstract

A method and system for controlling vehicle stability may comprise determining whether a vehicle is oversteering or understeering and, if the vehicle is oversteering or understeering, determining an amount by which to reduce a speed of the vehicle to correct for understeering or oversteering and applying brake pressure to at least the rear brakes of the vehicle to reduce vehicle speed. The method and system also may comprise determining an engine torque reduction amount based on vehicle oversteer or understeer conditions, reducing engine torque by the determined amount or to zero if the determined amount of engine torque reduction is greater than an actual engine torque, and applying braking to at least the rear brakes of the vehicle if the determined amount of engine torque reduction is greater than the actual engine torque.

Claims

1-12. -12. (canceled)

13. A system for controlling vehicle stability, the system comprising:

a controller for receiving one or more of input signals from vehicle sensors and calculations from previously-executed code, and, if the vehicle is oversteering or understeering, reducing a speed of the vehicle to correct for understeering or oversteering, wherein the controller sends a signal to apply brake pressure to various brakes of the vehicle to reduce vehicle speed, until an actual vehicle response close enough to a target vehicle response, and

wherein the target vehicle response is based on at least a steering wheel angle and a vehicle speed, and the actual vehicle response is based on a vehicle yaw rate or a vehicle sideslip gradient and sideslip angle.

14. The system of claim 13 wherein, upon initially applying brake pressure to rear wheels of the vehicle, balance is added to the vehicle while slowing the vehicle by swinging a rear tire force vector backwards until it is in parallel with a front tire force vector.

15. The system of claim 14, wherein brake pressure is applied to front and rear brakes of the vehicle simultaneously after application of brake pressure to the rear brakes of the vehicle.

16. The system of claim 15 wherein, if brake pressure is applied to the front and rear brakes of the vehicle simultaneously, the brake pressure is applied so that the front and rear tire force vectors are kept in parallel and are further rotated backwards.

17. The system of claim 16, wherein the magnitude of the brake pressure applied to each brake is in proportion to the normal force on the wheel to which the brake pressure is applied.

18. The system of claim 13, wherein the controller determines oversteer and understeer by comparing a target vehicle yaw rate with an actual vehicle yaw rate.

19. The system of claim 13, wherein the controller desensitizes control during transient maneuvers using control deadbands.

20. A system for controlling stability of a vehicle, the system comprising:

a brake system; and

a controller configured to control the brake system and receiving one or more of input signals from vehicle sensors and calculations from previously-executed code indicative of whether a vehicle is oversteering or understeering and, if the vehicle is oversteering or understeering, reducing a speed of the vehicle to correct for understeering or oversteering,

wherein the controller sends a signal to apply brake pressure to a wheel at an outside corner if the vehicle is oversteering, sends a signal to apply brake pressure to a wheel at an inside corner if the vehicle is understeering, and sends a signal to apply brake pressure to the vehicle'"'"'s rear wheels if application of brake pressure at the outside corner wheel or inside corner wheel does not make an actual vehicle response close enough to a target vehicle response, and

wherein the target vehicle response is based on at least a steering wheel angle and a vehicle speed, and the actual vehicle response is based on a vehicle yaw rate or a vehicle sideslip gradient and sideslip angle.

21. The system of claim 20 wherein, upon initially applying brake pressure to the rear wheels of the vehicle, balance is added to the vehicle while slowing the vehicle by swinging a rear tire force vector backwards until it is in parallel with a front tire force vector.

22. The system of claim 21, wherein brake pressure is applied to front and rear brakes of the vehicle simultaneously after application of brake pressure to the rear brakes of the vehicle.

23. The system of claim 22 wherein, if brake pressure is applied to the front and rear brakes of the vehicle simultaneously, the brake pressure is applied so that the front and rear tire force vectors are kept in parallel and are further rotated backwards.

24. The system of claim 23, wherein the magnitude of the brake pressure applied to each brake is in proportion to the normal force on the wheel to which the brake pressure is applied.

25. A system for controlling stability of a vehicle, the system comprising:

a brake system; and

a controller for receiving one or more of input signals from vehicle sensors and calculations from previously-executed code indicative of whether a vehicle is oversteering or understeering and, if the vehicle is oversteering or understeering, reducing a speed of the vehicle to correct for understeering or oversteering,

wherein the controller sends a signal to apply brake pressure to a wheel at an outside corner if the vehicle is oversteering, sends a signal to apply brake pressure to a wheel at an inside corner if the vehicle is understeering, and sends a signal to reduce engine torque if application of brake pressure at the outside corner wheel or inside corner wheel does not make an actual vehicle response close enough to a target vehicle response, and

wherein the target vehicle response is based on at least a steering wheel angle and a vehicle speed, and the actual vehicle response is based on a vehicle yaw rate or a vehicle sideslip gradient and sideslip angle.

26. The system of claim 25, wherein brake pressure is applied to rear wheels of the vehicle if application of brake pressure at the outside corner wheel or inside corner wheel does not make the actual vehicle response close enough to the target vehicle response.

27. The system of claim 26 wherein, upon initially applying brake pressure to rear wheels of the vehicle, balance is added to the vehicle while slowing the vehicle by swinging a rear tire force vector backwards until it is in parallel with a front tire force vector.

28. The system of claim 27, wherein brake pressure is applied to front and rear brakes of the vehicle simultaneously after application of brake pressure to the rear brakes of the vehicle.

29. The system of claim 28 wherein, if brake pressure is applied to the front and rear brakes of the vehicle simultaneously, the brake pressure is applied so that the front and rear tire force vectors are kept in parallel and are further rotated backwards.

30. The system of claim 29, wherein the magnitude of the brake pressure applied to each brake is in proportion to the normal force on the wheel to which the brake pressure is applied.