Method and apparatus for estimating yaw rate in a wheeled vehicle and stability system

• US 20030078700A1
• Filed: 08/20/2002
• Published: 04/24/2003
• Est. Priority Date: 08/20/2001
• Status: Active Grant

• Current Assignee: WiSys Technology Foundation, Inc.
• Original Assignee: Wisys Technology Foundation Incorporated
• Inventors: Chee, Wonshik
• Granted Patent: US 6,829,524 B2
• Time in Patent Office: Days
• US Class Current: 701/1
• CPC Class Codes: B60G 17/01908 Acceleration or inclination sensors characterised by the use of gyroscopes B60G21/08
• CPC Class Codes: B60G 17/0195 characterised by the regulation being combined with other vehicle control systems conjoint control of vehicle sub-units including control of suspension systems B60W10/22
• CPC Class Codes: B60G 2400/0523 Yaw rate
• CPC Class Codes: B60G 2400/1042 using at least two sensors
• CPC Class Codes: B60G 2800/702 Improving accuracy of a sensor signal
• CPC Class Codes: B60T 2250/03 Vehicle yaw rate
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60W 2422/95 Measuring the same parameter at multiple locations of the vehicle
• CPC Class Codes: B60W 2520/125 Lateral acceleration
• CPC Class Codes: B60W 2520/14 Yaw
• CPC Class Codes: B60W 2720/14 Yaw

Abstract

A method and apparatus for estimating vehicle yaw rate using a pair of single axis accelerometers that obviate the need for a gyroscope when used to provide a yaw rate estimate to a vehicle stability control system. The accelerometers are longitudinally aligned along an axis with one accelerometer in front of the vehicle center of gravity and one behind it. A method of estimating yaw rate uses a statistical estimating algorithm to process accelerometer inputs and a steer angle from a steer angle sensor on the vehicle.

Claims

1. An apparatus for providing data from which a yaw rate for a wheeled land vehicle can be estimated, the apparatus comprising a pair of spaced apart accelerometers.

2. The apparatus of claim 1 wherein the accelerometers are disposed along a common longitudinal axis of the wheeled land vehicle.

3. The apparatus of claim 2 wherein one of the accelerometers is disposed forwardly of a center of gravity of the wheeled land vehicle and another one of the accelerometers is disposed rearwardly of the center of gravity of the wheeled land vehicle.

5. The apparatus of claim 3 wherein each one of the accelerometers has a sensing axis that is disposed transversely and generally perpendicularly relative to the common longitudinal axis of the wheeled land vehicle.

6. The apparatus of claim 5 further comprising a processor that processes signals from both of the accelerometers to obtain an estimate of yaw rate.

7. The apparatus of claim 6 wherein the processor is configured to obtain an estimate of rate of change of yaw rate that is equal to a first result of an acceleration provided by the accelerometer that is disposed forwardly of the center of gravity of the wheeled land vehicle minus an acceleration provided by the accelerometer that is disposed rearwardly of the center of gravity of the wheeled land vehicle divided by a second result of a first distance between the forwardly disposed accelerometer and the center of gravity plus a second distance between the rearwardly disposed accelerometer and the center of gravity.

8. The apparatus of claim 7 wherein the processor is configured to obtain or determine an estimate of acceleration from the signal provided by each accelerometer.

9. The apparatus of claim 7 further comprising a steer angle sensor and wherein the processor is configured to take steer angle into account in determining a yaw rate.

10. The apparatus of claim 9 wherein the processor is further configured with a statistical estimating filter that helps drive yaw rate estimation error toward zero.

11. The apparatus of claim 9 wherein the statistical estimating filter comprises a Lewenberg filter.

12. The apparatus of claim 9 wherein the processor is configured with a state estimator.

13. The apparatus of claim 6 wherein the processor is configured with the following algorithm for determining an estimate of a rate of change of yaw rate:

14. The apparatus of claim 13 wherein error due to super-elevation and roll is ignored when determining an estimate of yaw rate.

4. The apparatus of claim 4 wherein yaw rate obtained is fed to a vehicle stability control system on board the wheeled land vehicle that lack a gyroscope.

15. An apparatus for providing data from which a yaw rate for a wheeled land vehicle can be determined, the apparatus comprising:

a pair of spaced apart accelerometers with one of the accelerometers being disposed rearwardly of a center of mass of the wheeled land vehicle and the other one of the accelerometers being disposed forwardly of a center of mass of the wheeled land vehicle and both of the sensors disposed along an axis that is parallel to a vehicle centerline;

a steer angle sensor; and

a processor configured to process signals or data from the accelerometers and the steer angle sensor and output a yaw rate.

16. The apparatus of claim 15 wherein the processor is configured with a state estimation algorithm that is used to process the signals or data from the accelerometers and the steer angle sensor and output a yaw rate.

17. The apparatus of claim 16 wherein the state estimation algorithm comprises a statistical estimating filter.

18. The apparatus of claim 16 wherein the state estimation algorithm comprises a Lewenberg estimator.

19. The apparatus of claim 15 wherein signals or data from the accelerometers and the steer angle sensor are processed in real time during operation of the wheeled vehicle to produce a yaw rate estimate and further comprising a vehicle stability control system that compares the yaw rate estimate with a yaw rate threshold to determine whether to activate the vehicle stability control system to increase vehicle stability.

20. A method estimating yaw rate comprising:

(a) providing a wheeled land vehicle having an onboard processor, a steer angle sensor, and a pair of spaced apart accelerometers;

(b) obtaining lateral accelerations from the accelerometers;

(c) obtaining a steer angle from the steer angle sensor; and

(d) estimating a yaw rate using the lateral accelerations and steer angle.

21. The method according to claim 20 wherein the processor is configured with a recursive statistical estimating algorithm that processes the steer angle and lateral accelerations.

22. The method according to claim 21 wherein the recursive statistical estimating algorithm applies feedback based on the prior estimated yaw rate and the present steer angle.