Steering Pull Compensation

• US 20100070135A1
• Filed: 09/12/2008
• Published: 03/18/2010
• Est. Priority Date: 09/12/2008
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Wang, Dexin, Sanders, Paul George
• Granted Patent: US 8,437,913 B2
• Time in Patent Office: Days
• US Class Current: 701/41
• CPC Class Codes: B62D 5/0472 for damping vibrations
• CPC Class Codes: B62D 6/007 adjustable by the driver, e.g. sport mode
• CPC Class Codes: B62D 6/04 responsive only to forces disturbing the intended course of the vehicle, e.g. forces acting transversely to the direction of vehicle travel

Abstract

A method for steering pull compensation to maintain a steering load below a predetermined threshold value. A straight line driving condition is verified through vehicle sensors and/or GPS, drive torque control is performed such that the steering load is kept below the predetermined threshold value. The steering pull compensation method may be disabled by a vehicle operator and is disabled in the absence of a verified straight line driving condition.

Claims

1. A method for compensating for steering pull during straight line driving conditions using a controller in a motor vehicle, the method comprising the steps of:

verifying a straight line driving condition; and

adjusting drive torque to maintain steering load below a predetermined threshold value.

8. The method as claimed in claim 1 wherein the step of verifying a straight line driving condition is accomplished using a GPS.

9. The method as claimed in claim 1 wherein the step of verifying a straight line driving condition is accomplished using a yaw rate sensor and a lateral acceleration sensor.

10. The method as claimed in claim 9 wherein the step of verifying a straight line driving condition is accomplished using a GPS.

2. The method as claimed in claim 2 wherein the step of adjusting drive torque further comprises adjusting drive torque in response to an estimated road crown angle.

3. The method as claimed in claim 3 further comprising the step of estimating road crown angle from a side force.

4. The method as claimed in claim 3 wherein the step of estimating road crown angle from the side force further comprises calculating side force from wheel force information.

5. The method as claimed in claim 4 wherein wheel force information is provided by an applied drive torque and steady state vehicle equations of motion.

6. The method as claimed in claim 4 wherein wheel force information is provided by vehicle body state sensors and estimations.

7. The method as claimed in claim 6 wherein wheel force information is provided by an applied drive torque and steady state vehicle equations of motion.

11. The method as claimed in claim 6 wherein the step of verifying a straight line driving condition is accomplished using a yaw rate sensor and a lateral acceleration sensor.

12. The method as claimed in claim 6 wherein the step of verifying a straight line driving condition is accomplished using a GPS.

13. The method as claimed in claim 12 wherein the step of verifying a straight line driving condition is accomplished using a GPS.

14. A method for compensating for steering pull during straight line driving conditions, the method comprising the steps of:

verifying a straight line driving condition;

sensing steering load, steering wheel rate, vehicle body yaw rate, and lateral acceleration; and

adjusting drive torque based on sensed values to maintain steering load below a predetermined threshold value only during a straight line driving condition.

15. The method as claimed in claim 14 wherein the step of adjusting the drive torque may be disabled on demand.

16. The method as claimed in claim 14 wherein the step of verifying a straight line driving condition further comprises comparing a product of the steering wheel rate and a steering load to a predetermined threshold, whereby in the event the product exceeds the predetermined threshold, a straight line driving condition is verifiable.

17. The method as claimed in claim 14 wherein the step of verifying a straight line driving condition further comprises sensing a steering wheel rate that approaches zero and sensing a steering load that is not equal to zero.

18. The method as claimed in claim 14 wherein the step of adjusting drive torque further comprises adjusting drive torque further comprises the step of estimating road crown angle.

19. The method as claimed in claim 18 wherein the step of estimating road crown angle further comprises calculating road crown angle from the relationship between a sensed vehicle side force, a sensed applied moment, a known vehicle weight, a known vehicle center of gravity position, and a tire pneumatic trail estimate for low-level tire lateral slip.

20. The method as claimed in claim 19 wherein the step of adjusting drive torque further comprises dynamically compensating drive torque in response to changes in the estimated road crown angle.