TRAILER LENGTH ESTIMATION METHOD USING TRAILER YAW RATE SIGNAL

• US 20160362135A1
• Filed: 06/11/2015
• Published: 12/15/2016
• Est. Priority Date: 06/11/2015
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Xu, Li, Tseng, Hongtei Eric, Pilutti, Thomas Edward
• Granted Patent: US 9,821,845 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B62D 13/06 for backing a normally drawn trailer
• CPC Class Codes: B62D 15/021 Determination of steering angle

Abstract

A backup assist system for a vehicle reversing a trailer includes a trailer sensor module generating a trailer yaw rate and a vehicle sensor system generating a vehicle yaw rate and a vehicle speed. The system further includes a controller determining an estimated length of the trailer based on an estimated hitch angle, the vehicle yaw rate, the vehicle speed, and the trailer yaw rate in view of a kinematic relationship.

Claims

1. A backup assist system for a vehicle reversing a trailer, comprising:

a trailer sensor module generating a trailer yaw rate;

a vehicle sensor system generating a vehicle yaw rate and a vehicle speed; and

a controller determining an estimated length of the trailer based on an estimated hitch angle, the vehicle yaw rate, the vehicle speed, and the trailer yaw rate in view of a kinematic relationship.

2. The system of claim 1, wherein the estimated hitch angle is a reference estimated hitch and angle is determined by the controller using an integration of a difference between the trailer yaw rate and the vehicle yaw rate over a predetermined period of time.

3. The system of claim 2, wherein the reference estimated hitch angle is further determined by adding an initial reference hitch angle to the integration of the difference between the trailer yaw rate and the vehicle yaw rate over the predetermined period of time, the initial reference hitch angle corresponding to a start point of the predetermined period of time.

4. The system of claim 3, wherein the initial reference estimated hitch angle is determined using an equation derived from the kinematic model that is independent of a trailer length measurement.

5. The system of claim 2, wherein the system performs the integration of over the predetermined period of time before estimating the length of the trailer.

6. The system of claim 2, wherein the controller:

sequentially derives a plurality of estimated trailer lengths based on corresponding ones of a plurality of reference estimated hitch angles; and

derives a final weighted trailer length estimate by one of averaging and filtering the plurality of instantaneous estimated trailer lengths.

7. The system of claim 2, wherein the system determines the estimated length of the trailer using the reference estimated hitch angle in view of the kinematic relationship.

8. The system of claim 7, wherein the controller simultaneously and instantaneously determines the estimated hitch angle and the estimated length of the trailer.

9. The system of claim 8, wherein the controller instantaneously determines the estimated hitch angle using the estimated length of the trailer.

10. The system of claim 8, wherein the controller:

compares the estimated hitch angle with the reference estimated hitch angle to determine an error signal; and

adjusts the trailer length estimate using the error signal.

11. The system of claim 1, further including a curvature input device outputting a first curvature signal, wherein:

the controller further implements a trailer backup mode including reversing the trailer based on the first curvature signal, the estimated length of the trailer, and the estimated hitch angle in view of the kinematic relationship.

12. A system for estimating the length of a trailer towed by a vehicle, comprising

a first sensor coupled with the trailer for determining a trailer yaw rate;

a second sensor coupled with the vehicle for determining a vehicle yaw rate; and

a controller determining an estimated length of the trailer based on an estimated hitch angle, the vehicle yaw rate, the vehicle speed, and the trailer yaw rate in view of a kinematic relationship between the trailer and the vehicle.

13. The system of claim 12, wherein the estimated hitch angle is a reference estimated hitch angle is determined by the controller using an integration of a difference between the trailer yaw rate and the vehicle yaw rate over a predetermined period of time.

14. The system of claim 13, wherein the controller:

sequentially derives a plurality of estimated trailer lengths based on corresponding ones of a plurality of reference estimated hitch angles; and

derives a final weighted trailer length estimate by one of averaging and filtering the plurality of instantaneous estimated trailer lengths.

15. The system of claim 12, wherein the controller simultaneously and instantaneously determines the estimated hitch angle and the estimated length of the trailer.

16. The system of claim 15, wherein the controller:

compares the estimated hitch angle with a reference estimated hitch angle to determine an error signal; and

adjusts the trailer length estimate using the error signal.

17. A method for estimating the length of a trailer towed by a vehicle, comprising:

receiving a trailer yaw rate signal;

receiving a vehicle yaw rate signal;

receiving a vehicle speed signal; and

determining an estimated length of the trailer based on an estimated hitch angle, the vehicle yaw rate signal, the vehicle speed signal, and the trailer yaw rate signal in view of a kinematic relationship between the trailer and the vehicle.

18. The method of claim 17, wherein the estimated hitch angle is a reference estimated hitch angle and is determined by integrating a difference between the trailer yaw rate and the vehicle yaw rate over a predetermined period of time.

19. The method of claim 18, further comprising:

sequentially determining a plurality of estimated trailer lengths based on corresponding ones of a plurality of reference estimated hitch angles; and

deriving a final weighted trailer length estimate by one of averaging and filtering the plurality of instantaneous estimated trailer lengths.

20. The method of claim 19, wherein the estimated hitch angle and the estimated length of the trailer are simultaneously and instantaneously determine, the method further comprising:

comparing the estimated hitch angle with a reference estimated hitch angle to determine an error signal; and

adjusting the trailer length estimate using the error signal.