Hitch angle detection for trailer backup assist system

• US 9,610,975 B1
• Filed: 12/17/2015
• Issued: 04/04/2017
• Est. Priority Date: 12/17/2015
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Hu, Zheng, Joyce, John P.
• Primary Examiner(s): Dager, Jonathan M
• Application Number:
  US14/972,761
• Time in Patent Office: 474 Days
• Field of Search: None
• CPC Class Codes: B60D 1/06 Ball-and-socket hitches , e.g. constructional details, auxiliary devices, their arrangement on the vehicle
• CPC Class Codes: B60D 1/145 consisting of an elongated single bar or tube
• CPC Class Codes: B60D 1/245 for facilitating push back or parking of trailers
• CPC Class Codes: B60D 1/62 involving supply lines, electric circuits, or the like
• CPC Class Codes: B60Q 5/00 Arrangement or adaptation of acoustic signal devices
• CPC Class Codes: B60W 10/18 including control of braking systems
• CPC Class Codes: B62D 13/06 for backing a normally drawn trailer

Abstract

A system for detecting a hitch angle between a vehicle and a trailer is provided herein. An imaging device is configured to capture images of the trailer and a controller is configured to process images captured by the imaging device. The controller derives a template image having a trailer contour and matches the template image to a search image. The hitch angle is determined based on a positional relationship between the template image and the search image.

Claims

1. A system for detecting a hitch angle between a vehicle and a trailer, comprising:

an imaging device configured to capture images of the trailer;

a controller configured to;

process images captured by the imaging device;

derive a template image having a trailer contour; and

match the template image to a search image;

wherein the hitch angle is determined based on a positional relationship between the template image and the search image;

wherein the controller matches the template image to the search image by rotating the template image relative to the search image about a rotation point; and

wherein the hitch angle correlates to an angle at which the template image is rotated relative to the search image to generate a match therebetween.

2. The system of claim 1, wherein the controller derives the template image by:

deriving an averaged image of all images captured by the imaging device during a period of time in which the vehicle and the trailer are moving in a straight direction;

calculating an edge value for each pixel of the averaged image;

comparing the edge value of each pixel to a threshold value to identify between trailer pixels and ground pixels; and

determining the trailer contour based on identified trailer pixels.

3. The system of claim 2, wherein pixels having edge values that meet or exceed the threshold value are identified as trailer pixels and pixels having edge values that do not meet or exceed the threshold value are identified as ground pixels.

4. The system of claim 1, wherein the controller monitors the displacement of the trailer contour relative to a proximity zone in the search image and initiates a jackknife countermeasure if the trailer contour crosses into the proximity zone.

5. The system of claim 4, wherein the proximity zone is defined as a space between an imaged rear bumper of the vehicle and a boundary line that is defined by the controller and is overlaid onto the search image.

6. The system of claim 4, wherein the jackknife countermeasure comprises generating an auditory warning via a vehicle alert system, generating a visual warning via a vehicle display, generating a braking command to a vehicle brake control system, reducing a torque of a vehicle powertrain control system, modifying a steering angle of the vehicle, or a combination thereof.

7. A system for detecting a hitch angle between a vehicle and a trailer, comprising:

an imaging device configured to capture images of the trailer;

a controller configured to;

process images captured by the imaging device;

derive a template image having a trailer contour;

rotate the template image relative to a search image about an imaged hitch point that is common to the template image and the search image; and

determine the hitch angle based on an angle at which the template image is rotated relative to the search image to generate a match therebetween.

8. The system of claim 7, wherein the controller derives the template image by:

deriving an averaged image of all images captured by the imaging device during a period of time in which the vehicle and the trailer are moving in a straight direction;

calculating an edge value for each pixel of the averaged image;

comparing the edge value of each pixel to a threshold value to identify between trailer pixels and ground pixels; and

determining the trailer contour based on identified trailer pixels.

9. The system of claim 8, wherein pixels having edge values that meet or exceed the threshold value are identified as trailer pixels and pixels having edge values that do not meet or exceed the threshold value are identified as ground pixels.

10. The system of claim 7, wherein the controller monitors the displacement of the trailer contour relative to a proximity zone in the search image and initiates a jackknife countermeasure if the trailer contour crosses into the proximity zone.

11. The system of claim 10, wherein the proximity zone is defined as a space between an imaged rear bumper of the vehicle and a boundary line that is defined by the controller and is overlaid onto the search image.

12. The system of claim 10, wherein the jackknife countermeasure comprises generating an auditory warning via a vehicle alert system, generating a visual warning via a vehicle display, generating a braking command to a vehicle brake control system, reducing a torque of a vehicle powertrain control system, modifying a steering angle of the vehicle, or a combination thereof.

13. A method for detecting a hitch angle between a vehicle and a trailer, comprising the steps of:

capturing images of the trailer using an imaging device;

providing a controller configured to;

process images captured by the imaging device;

derive a template image having a trailer contour; and

match the template image to a search image;

wherein the hitch angle is determined based on a positional relationship between the template image and the search image;

wherein the controller matches the template image to the search image by rotating the template image relative to the search image about a rotation point; and

wherein the hitch angle correlates to an angle at which the template image is rotated relative to the search image to generate a match therebetween.

14. The method of claim 13, wherein the controller derives the template image by:

deriving an averaged image of all images captured by the imaging device during a period of time in which the vehicle and the trailer are moving in a straight direction;

calculating an edge value for each pixel of the averaged image;

comparing the edge value of each pixel to a threshold value to identify between trailer pixels and ground pixels; and

determining the trailer contour based on identified trailer pixels.

15. The method of claim 14, wherein pixels having edge values that exceed the threshold value are identified as trailer pixels and pixels having edge values that do not exceed the threshold value are identified as ground pixels.

16. The method of claim 13, wherein the controller monitors the displacement of the trailer contour relative to a proximity zone in the search image and initiates a jackknife countermeasure if the trailer contour crosses into the proximity zone.

17. The method of claim 16, wherein the proximity zone is defined as a space between an imaged rear bumper of the vehicle and a boundary line that is defined by the controller and is overlaid onto the search image.

18. The method of claim 16, wherein the jackknife countermeasure comprises generating an auditory warning via a vehicle alert system, generating a visual warning via a vehicle display, generating a braking command to a vehicle brake control system, reducing a torque of a vehicle powertrain control system, modifying a steering angle of the vehicle, or a combination thereof.