VEHICLE SPEED CONTROL SYSTEM AND METHOD

• US 20170001645A1
• Filed: 01/13/2015
• Published: 01/05/2017
• Est. Priority Date: 01/24/2014
• Status: Active Grant

• Current Assignee: Jaguar Land Rover Limited (TATA Motors Limited)
• Original Assignee: Jaguar Land Rover Limited (TATA Motors Limited)
• Inventors: FAIRGRIEVE, Andrew, KELLY, James
• Granted Patent: US 10,259,460 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60K 28/16 responsive to, or preventing, skidding of wheels brake control systems for vehicle drive stability B60T8/1755; arrangements responsive to a speed condition for adjusting wheel braking force B60T8/32; control of vehicle driving stability otherwise than by controlling the propulsion unit only B60W30/02; preventing wheel slippage by reducing power in rail vehicles B61C15/00
• CPC Class Codes: B60T 2210/16 Off-road driving conditions
• CPC Class Codes: B60T 8/175 Brake regulation specially adapted to prevent excessive wheel spin during vehicle acceleration, e.g. for traction control safety devices for propulsion unit control responsive to, or preventing, skidding of wheels B60K28/16
• CPC Class Codes: B60W 10/184 with wheel brakes
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2520/28 Wheel speed
• CPC Class Codes: B60W 2552/40 Coefficient of friction
• CPC Class Codes: B60W 2555/20 Ambient conditions, e.g. wind or rain
• CPC Class Codes: B60W 2710/12 Differentials
• CPC Class Codes: B60W 2720/103 Speed profile
• CPC Class Codes: B60W 2720/30 Wheel torque
• CPC Class Codes: B60W 30/143 Speed control B60W30/16 takes precedence
• CPC Class Codes: B60W 30/18172 Preventing, or responsive to skidding of wheels

Abstract

A vehicle control system comprising a speed control system and a traction control (TC) system, the TC system being operable to cause a reduction in speed of one or more wheels when a speed of the one or more wheels exceeds a TC system intervention threshold value, the speed control system being operable in an active state in which the speed control system causes the vehicle to operate in accordance with a target speed value, wherein when the speed control system is in the active state, the TC system intervention threshold value is set to a value selected in dependence at least in part on the target speed value.

Claims

1. A vehicle control system comprising a speed control system and a traction control system,

the traction control system being operable to cause a reduction in speed of one or more wheels when a speed of the one or more wheels exceeds a traction control system intervention threshold value,

the speed control system being operable in an active state in which the speed control system causes the vehicle to operate in accordance with a target speed value,

wherein when the speed control system is in the active state, the traction control system intervention threshold value is set to a value selected in dependence at least in part on the target speed value.

2. A system according to claim 1 configured to determine a vehicle reference speed value, the vehicle reference speed value being an estimated speed of the vehicle over ground and wherein when the speed control system is active the traction control system intervention threshold value is set to a value determined in dependence on the value of the lower of the target speed value and the vehicle reference speed value.

4. A system according to claim 1 wherein when the speed control system is not controlling vehicle speed the traction control system intervention threshold value is set to a first traction control system intervention threshold value.

5. A system according to claim 2 wherein when the speed control system is not controlling vehicle speed the traction control system intervention threshold value is set to a first traction control system intervention threshold value the first traction control system intervention threshold value is determined in dependence at least in part on the vehicle reference speed value.

6. A system according to claim 5 wherein the traction control system intervention threshold value is a wheel speed value relative to a stationary wheel condition, wherein when the speed control system is controlling vehicle speed the traction control intervention threshold value is set to a value substantially equal to the lower of the target speed value multiplied by an intervention factor and the first traction control system intervention threshold value.

7. A system according to claim 4 wherein the first traction control system intervention threshold value is a wheel speed value relative to a stationary wheel condition, and wherein the first traction control system intervention threshold value is substantially equal to the reference speed value plus a first intervention offset value.

8. A system according to claim 1 wherein the traction control system intervention threshold value and/or first traction control system intervention threshold value correspond to a wheel speed value relative to the vehicle reference speed value, the traction control system being operable to cause a reduction in speed of one or more wheels when a speed of the one or more wheels relative to the vehicle reference speed value exceeds the traction control system intervention threshold value.

9. A system according to claim 2 wherein the speed control system is configured to cause the vehicle to operate in accordance with the target speed value, the speed control system being arranged to employ a speed control system reference speed value to determine instant vehicle speed, and wherein the speed control system reference speed value is set substantially equal to one of a mean speed of the driving wheels, and the speed of the slowest turning driving wheel.

13. A system according to claim 9 wherein the traction control system intervention threshold value is a wheel speed value relative to a stationary wheel condition, wherein when the speed control system is controlling vehicle speed the traction control intervention threshold value is set to a value substantially equal to the lower of the target speed value multiplied by an intervention factor and the first traction control system intervention threshold value, and when the vehicle is configured for driving with N driving wheels the intervention factor is set to a value greater than 1 and less than N/(N−

1).

14. A system according to claim 13 wherein when the vehicle is configured for driving with four driving wheels the intervention factor is set to a value in the range from 1.1-1.3.

15. A system according to claim 1 wherein in the active state the speed control system is configured to cause the vehicle to operate in accordance with the target speed value by causing the vehicle to travel at a speed substantially equal to the target speed value and wherein in the active state the speed control system is configured to cause the vehicle to operate in accordance with the target speed value by causing the speed control system reference speed value to be substantially equal to the target speed value.

20. A system according to claim 1 wherein the traction control system intervention threshold value is set to a value determined in dependence at least in part on the target speed value at least when the target speed value is less than a vehicle reference speed value, the reference speed value corresponding to an estimated speed of the vehicle over ground.

21. A motor vehicle comprising a control system according to claim 1.

3. (canceled)

10-12. -12. (canceled)

16-19. -19. (canceled)

22. (canceled)

23. A method of controlling a vehicle by means of a speed control system and a traction control system, the method comprising

causing by means of the traction control system a reduction in speed of one or more wheels when a speed of the one or more wheels exceeds a traction control system intervention threshold value;

and

when the speed control system is in an active state, causing the vehicle to operate in accordance with a target speed value and setting the traction control system intervention threshold value to a value selected in dependence at least in part on the target speed value.

24. A method according to claim 23 comprising determining a vehicle reference speed value, the vehicle reference speed value corresponding to an estimated speed of the vehicle over ground.

25. A method according to claim 24 whereby when the speed control system is active the method comprises setting the traction control system intervention threshold value to a value determined in dependence on the value of the lower of the target speed value and the vehicle reference speed value.

26. A method according to claim 23 whereby when the speed control system is not controlling vehicle speed the method comprises setting the traction control system intervention threshold value to a first traction control system intervention threshold value.

27. A method according to claim 25 whereby when the speed control system is not controlling vehicle speed the method comprises setting the traction control system intervention threshold value to a first traction control system intervention threshold value and when the speed control system is controlling vehicle speed the method comprises setting the traction control intervention threshold value to a value substantially equal to the lower of the target speed value multiplied by an intervention factor and the first traction control system intervention threshold value.

28. A method according to claim 27 comprising determining a vehicle reference speed value, the vehicle reference speed value corresponding to an estimated speed of the vehicle over ground determining the first traction control system intervention threshold value in dependence at least in part on vehicle reference speed value and setting the first traction control system intervention threshold value to a value substantially equal to the reference speed value plus a first intervention offset value.

30. A method according to claim 27 comprising causing the vehicle to operate in accordance with the target speed value, whereby causing the vehicle to operate in accordance with the target speed value comprises employing a speed control system reference speed value to determine instant vehicle speed, setting the speed control system reference speed value to a value determined in dependence on one of a mean speed of the driving wheels and the speed of the slowest turning driving wheel, and whereby the vehicle is configured for driving with N driving wheels and the intervention factor is set to a value greater than 1 and less than N/(N−

1).

29. (canceled)

31-41. -41. (canceled)