Adaptive steering control for robustness to errors in estimated or user-supplied trailer parameters

• US 10,730,553 B2
• Filed: 09/27/2017
• Issued: 08/04/2020
• Est. Priority Date: 09/27/2017
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Raad, Joseph M., Daavettila, Tyler, Buss, Brian George, Mattern, Donald Jacob
• Primary Examiner(s): Wallace, Donald J
• Application Number:
  US15/717,210
• Publication Number:
  US 20190092388A1
• Time in Patent Office: 1,042 Days
• CPC Class Codes: B62D 13/005 operated from tractor steering system
• CPC Class Codes: B62D 13/06 for backing a normally drawn trailer
• CPC Class Codes: B62D 15/024 Other means for determination of steering angle without directly measuring it, e.g. deriving from wheel speeds on different sides of the car
• CPC Class Codes: B62D 15/025 Active steering aids, e.g. helping the driver by actively influencing the steering system after environment evaluation B62D1/28 takes precedence

Abstract

A system for assisting in reversing of a vehicle-trailer combination includes a vehicle steering system and a controller. The controller outputs a steering signal to the steering system to maintain the vehicle-trailer combination along a straight backing path and determines a straight-backing offset of a hitch angle in the vehicle-trailer combination as a proportion of an integral of a measured characteristic of the vehicle-trailer combination that varies from a desired zero value.

Claims

1. A system for assisting in reversing of a vehicle-trailer combination, comprising:

a vehicle steering system; and

a controller;

outputting a steering signal to the steering system to maintain the vehicle-trailer combination along a straight backing path;

determining a straight-backing offset of a hitch angle in the vehicle-trailer combination, due to a slip in a pair of wheels in at least one of a trailer or a vehicle in the vehicle-trailer combination, as a proportion of an integral of a measured characteristic of the vehicle-trailer combination that varies from a desired zero value due to the slip.

2. The system of claim 1, wherein the controller further uses the offset of the hitch angle to dynamically adjust the steering signal.

3. The system of claim 1, wherein:

the steering signal further maintains a trailer of the vehicle-trailer combination on a path corresponding with a commanded curvature within a range of curvature values; and

the straight backing path corresponds with a commanded curvature of zero.

4. The system of claim 1, wherein:

the offset of the hitch angle is further due to one of an irregularity associated with the trailer or an error in a measurement of the hitch angle; and

the measured characteristic of the vehicle-trailer combination further varies from the desired zero value due to the one of the trailer irregularity or the error.

5. The system of claim 1, wherein the slip in the pair of wheels occurs due to a slope in a surface beneath the pair of wheels at least partially transverse to the straight backing path.

6. The system of claim 1, further including a vehicle yaw rate sensor mounted to a vehicle in the vehicle-trailer combination and in communication with the controller, wherein:

the characteristic is a yaw rate of the vehicle; and

the controller measures the yaw rate using an input from the vehicle yaw rate sensor.

7. The system of claim 1, further including a trailer yaw rate sensor mounted to a trailer in the vehicle-trailer combination and in communication with the controller, wherein:

the characteristic is a yaw rate of the trailer; and

the controller measures the yaw rate using an input from the trailer yaw rate sensor.

8. The system of claim 1, wherein:

the vehicle steering system controls an angle of a pair of steered wheels of a vehicle in the vehicle-trailer combination and measures the angle of the pair of steered wheels during such controlling;

the controller receives a measurement of the angle of the pair of steered wheels from the vehicle steering system; and

the characteristic is the angle of the pair of steered wheels.

9. The system of claim 3, wherein:

the opposing ranges of curvature include maximum curvatures at respective ends thereof; and

the controller further;

outputs the steering signal to the steering system to maintain the vehicle-trailer combination along a maximum-curved backing path corresponding with one of the maximum curvatures;

determines a maximum-curvature offset of the hitch angle based on an error between a measured steady-state steering angle and a predicted steady-state steering angle based on the maximum curvature; and

interpolates a hitch angle offset function using the straight-backing offset and the maximum-curvature offset.

10. A system for assisting in reversing of a vehicle-trailer combination, comprising:

a vehicle steering system; and

a controller;

outputting a steering signal to the steering system to maintain the vehicle-trailer combination along a commanded path corresponding with opposing ranges of curvature;

when the commanded path is a straight backing path corresponding with a curvature of zero, determining a straight-backing offset of a hitch angle in the vehicle-trailer combination;

when the commanded path is a maximum-curvature path corresponding with one of two maximum curvatures at respective ends of the opposing ranges of curvature, determining a maximum-curvature offset of the hitch angle; and

interpolating a hitch angle offset function using the straight-backing offset and the maximum-curvature offset.

11. The system of claim 10, wherein the controller determines the straight-backing offset of the hitch angle as a proportion of an integral of a measured behavior of a characteristic of the vehicle-trailer combination that varies from a desired zero value.

12. The system of claim 11, wherein the vehicle steering system controls an angle of a pair of steered wheels of a vehicle in the vehicle-trailer combination and measures the angle of the pair of steered wheels during such controlling;

the controller receives a measurement of the angle of the pair of steered wheels from the vehicle steering system; and

the characteristic is the angle of the pair of steered wheels.

13. The system of claim 10, wherein the controller determines the maximum-curvature offset of the hitch angle based on an error between a measured steady-state steering angle and a predicted steady-state steering angle based on the maximum curvature.

14. The system of claim 10, wherein the controller further uses the hitch angle offset function to dynamically adjust the steering signal.

15. A method for assisting in reversing of a vehicle-trailer combination, comprising:

outputting a steering signal to maintain a trailer in the vehicle-trailer combination along a straight backing path;

determining a straight-backing offset of a hitch angle in the vehicle-trailer combination as a proportion of an integral of a measured behavior of a characteristic of the vehicle-trailer combination that varies from a desired zero value, wherein the offset of the hitch angle is due to a slip in a pair of wheels in at least one of the trailer or a vehicle in the vehicle-trailer combination due to a slope in a surface beneath the pair of wheels at last partially transverse to the straight backing path and the measured behavior of the characteristic of the vehicle-trailer combination varies from the desired zero value due to the slip; and

dynamically adjusting the steering signal using the straight-backing offset.

16. The method of claim 15, wherein:

the controller is configured to maintain the trailer of the vehicle-trailer combination on a commanded path corresponding with opposing ranges of curvature; and

the straight backing path corresponds with a commanded curvature of zero.

17. The method of claim 16, wherein the opposing ranges of curvature include maximum curvatures at respective ends thereof;

and

the method further includes;

outputting the steering signal to the steering system to maintain the vehicle-trailer combination along a maximum-curved backing path corresponding with one of the maximum curvatures;

determining a maximum-curvature offset of the hitch angle based on an error between a measured steady-state steering angle and a predicted steady-state steering angle based on the maximum curvature;

interpolating a hitch angle offset function using the straight-backing offset and the maximum-curvature offset; and

dynamically adjusting the steering signal using the hitch angle offset function, including using the straight-backing offset when the commanded curvature is zero.