Vehicle and method of control thereof

Patent metadata

Field	Value
Publication number	US-9511777-B2
Application number	US-201314407334-A
Country	US
Kind code	B2
Filing date	Jun 10, 2013
Priority date	Jun 11, 2012
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

Embodiments of the present invention provide a control system for a motor vehicle, the control system being operable to determine a vehicle speed value corresponding to a speed of travel of the vehicle over a surface according to a value of a speed of a wheel of the vehicle, the control system being operable to: cause a reduction in an amount of drive torque applied to at least one of a plurality of driven wheels; obtain a value of a speed of rotation of the at least one wheel while the amount of drive torque applied thereto is reduced; and determine the vehicle speed value according to the measured value of wheel speed, wherein the system is configured to determine whether the vehicle speed value obtained according to the speed of the wheel following the reduction in torque applied to the wheel is consistent with one or more vehicle speed measurements made by alternative means.

First claim

The invention claimed is:

1. A control system for a motor vehicle, the control system being operable to determine a vehicle speed value corresponding to a speed of travel of the vehicle over a surface according to a value of a speed of a wheel of the vehicle, the control system being operable to:
cause a reduction in an amount of drive torque applied to at least one of a plurality of driven wheels;
obtain a value of a speed of rotation of the at least one wheel whilst the amount of drive torque applied thereto is reduced; and
determine the vehicle speed value according to the measured value of wheel speed, wherein the system is configured to determine whether the vehicle speed value obtained according to the speed of the wheel following the reduction in torque applied to the wheel is consistent with one or more vehicle speed measurements made by alternative means.

2. A control system as claimed in claim 1 operable to control a motor vehicle having at least one driven front wheel and at least one driven rear wheel, the control system being operable to cause a reduction in the amount of drive torque applied to the at least one driven front wheel of the vehicle and not to the at least one driven rear wheel when it is required to verify vehicle speed.

3. A control system as claimed in claim 2 operable to control a vehicle having at least a pair of driven front wheels and at least a pair of driven rear wheels, the control system being operable to cause a reduction in the amount of drive torque applied to each wheel of the at least one pair of driven front wheels and not to the at least one pair of driven rear wheels.

4. A control system as claimed in claim 1 configured to cause a reduction in the drive torque applied to the at least one driven wheel by one selected from amongst a substantially fixed proportion of the total drive torque applied to the wheel, and a substantially fixed amount of torque.

5. A control system as claimed in claim 1 configured to cause a reduction in the drive torque applied to the driven wheel to a value below a traction limit of that wheel.

6. A control system as claimed in claim 1 wherein if the vehicle speed obtained according to the wheel speed measured following the reduction in drive torque applied to the wheel is not consistent with one or more vehicle speed measurements made by alternative means the control system is operable to reduce an amount of drive torque applied to the at least one of the plurality of driven wheels still further, subsequently to determine again whether the vehicle speed according to the wheel speed measured following the further reduction in torque applied to the at least one wheel is consistent with one or more vehicle speed measurements made by alternative means.

7. A control system as claimed in claim 1 operable periodically to determine vehicle speed by automatically reducing an amount of drive torque applied to the at least one of the plurality of driven wheels, and measuring a speed of rotation of the at least one wheel whilst the amount of torque applied to the at least one wheel is reduced.

8. A control system as claimed in claim 1 operable to measure vehicle speed by means of an accelerometer, the control system being configured periodically to verify vehicle speed measured using the accelerometer by reducing the amount of torque applied to at least one of the plurality of driven wheels; and measuring a speed of rotation of the at least one wheel whilst the amount of torque applied to the at least one wheel is reduced.

9. A control system as claimed in claim 1 operable to reduce an amount of torque applied to at least one of a plurality of driven wheels and to measure a speed of rotation of the at least one wheel whilst the amount of torque applied to the at least one wheel is reduced when it is determined that an estimated value of vehicle speed is not consistent with vehicle speed measured according to a value of wheel speed.

10. A control system as claimed in claim 1 operable to assume a mode in which vehicle speed is verified at prescribed time intervals following launch of a vehicle from a substantially stationary condition.

11. A control system as claimed in claim 1 operable to assume a mode in which vehicle speed is determined at prescribed time intervals during periods in which a rate of increase of an amount of torque applied to one or more driven wheels exceeds a prescribed rate.

12. A control system as claimed in claim 1 operable to control the vehicle to reduce the amount of torque applied to the at least one of the plurality of driven wheels by reducing an amount of drive torque transmitted from a propulsion motor to the at least one wheel.

13. A control system as claimed in claim 1 operable to control the vehicle to reduce the amount of torque applied to the at least one of the plurality of driven wheels by reducing an amount of drive torque generated by a propulsion motor.

14. A control system as claimed in claim 1 operable to control the vehicle to reduce the amount of torque applied to the at least one of the plurality of driven wheels by application of brake means to the at least one of the plurality of driven wheels.

15. A vehicle powertrain comprising a control system as claimed in claim 1 .

16. A vehicle comprising a control system as claimed in claim 1 .

17. A vehicle as claimed in claim 16 wherein each of a pair of front driven wheels and a pair of rear driven wheels is provided with a respective propulsion motor.

18. A vehicle as claimed in claim 17 wherein each of the propulsion motors comprises an electric propulsion motor.

19. A method of determining speed of travel of a vehicle over a surface implemented by a control system comprising:
causing a reduction in an amount of drive torque applied to at least one of a plurality of driven wheels;
obtaining a value of a speed of rotation of the at least one wheel whilst the amount of drive torque applied thereto is reduced; and
determining the vehicle speed value according to the measured value of wheel speed, wherein the system is configured to determine whether the vehicle speed value obtained according to the speed of the wheel following the reduction in torque applied to the wheel is consistent with one or more vehicle speed measurements made by alternative means.

Assignees

• Jaguar Land Rover Ltd

Inventors

• Blyth Michael
• Beever Paul

Classifications

• B60W40/105 Primary

  Speed · CPC title

• B60W2520/26

  Wheel slip · CPC title

• B60W2720/28

  Wheel speed · CPC title

• B60W2520/28

  Wheel speed · CPC title

• B60W2520/10

  Longitudinal speed · CPC title