System and method for calculating a horizontal camera to target distance

• US 9,374,562 B2
• Filed: 04/10/2014
• Issued: 06/21/2016
• Est. Priority Date: 04/19/2011
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Trombley, Roger Arnold, Nave, Christopher Scott, Lavoie, Erick Michael, Hockrein, Bradley G., Mattern, Don Jacob
• Primary Examiner(s): Black, Thomas G
• Assistant Examiner(s): Kong, Sze-Hon
• Application Number:
  US14/249,781
• Publication Number:
  US 20140218506A1
• Time in Patent Office: 803 Days
• Field of Search: 701/28, 701/42, 348/148
• US Class Current: 1/1
• 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: B60D 3/00 Fittings to facilitate pushing B60D1/00 takes precedence; vehicle bumpers B60R19/02; steering arrangements for backing a normally-drawn trailer B62D13/06
• CPC Class Codes: B60Q 9/005 using a video camera
• CPC Class Codes: B60R 1/003 for viewing trailer hitches
• CPC Class Codes: B60T 8/1708 for lorries or tractor-trailer combinations
• CPC Class Codes: B60W 30/00 Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
• CPC Class Codes: B62D 12/00 Steering specially adapted for vehicles operating in tandem or having pivotally connected frames steering endless tracks or the like B62D11/00; steering specially adapted for trailers B62D13/00
• CPC Class Codes: B62D 13/00 Steering specially adapted for trailers combined traction and steering hitches B60D
• CPC Class Codes: B62D 13/06 for backing a normally drawn trailer
• CPC Class Codes: B62D 15/02 Steering position indicators ; Steering position determination; Steering aids
• CPC Class Codes: B62D 15/027 Parking aids, e.g. instruction means
• CPC Class Codes: B62D 15/028 Guided parking by providing commands to the driver, e.g. acoustically or optically
• CPC Class Codes: B62D 15/0285 Parking performed automatically
• CPC Class Codes: B62D 53/045 with rigid linkage in the horizontal plane luggage trailers B62D63/064 - B62D63/067
• CPC Class Codes: B62D 9/00 Steering deflectable wheels not otherwise provided for steering positon indicators B62D15/02
• CPC Class Codes: G01B 7/30 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: H04N 7/183 for receiving images from a single remote source

Abstract

A system and method for calculating a horizontal camera to target distance is provided. A camera on board a vehicle is configured to image a target on a trailer that is aligned with the vehicle. A controller is in communication with the camera and is supplied a user-obtained measurement. The controller is configured to calculate a first horizontal distance and a second horizontal distance, and to sum the first and second horizontal distances to calculate a horizontal camera to target distance.

Claims

1. A trailer backup assist system comprising:

a camera configured to image a target on a trailer that is aligned with a vehicle; and

a controller configured to;

estimate a target to ground measurement based on a draw bar drop measurement obtained by a user;

calculate a first and a second horizontal distance; and

sum the first and the second horizontal distance to calculate a horizontal camera to target distance.

2. The trailer backup assist system of claim 1, wherein the camera has a vertical field of view defined by a lower field extent and an upper field extent, and wherein the first horizontal distance extends horizontally from the camera to an intersection point between the lower field extent and a centerline longitudinal axis of the target.

3. The trailer backup assist system of claim 2, wherein the controller calculates the first horizontal distance using a camera to ground distance and an angle between a vertical axis extending through the camera and the lower field extent.

4. The trailer backup assist system of claim 3, wherein the second horizontal distance extends horizontally from the intersection point to a target midpoint.

5. The trailer backup assist system of claim 4, wherein the controller calculates the second horizontal distance using a camera to intersection point distance, a camera to target midpoint distance, and an angle between the camera to target midpoint distance and the camera to intersection point distance.

6. A trailer backup assist system comprising:

a camera on board a vehicle and having a vertical field of view defined by a lower field extent and an upper field extent for imaging a target located on a trailer;

an input device for entering a user-obtained measurement; and

a controller for receiving image data from the camera and the user-obtained measurement to calculate a first horizontal distance and a second horizontal distance;

wherein the first horizontal distance extends horizontally from the camera to an intersection point between the lower field extent and a centerline longitudinal axis of the target; and

wherein the second horizontal distance extends horizontally from the intersection point to a target midpoint.

7. The trailer backup assist system of claim 6, wherein the user-obtained measurement comprises one of a target to ground distance and a draw bar drop measurement.

8. The trailer backup assist system of claim 6, wherein the controller calculates the horizontal camera to target distance by summing the first horizontal distance and the second horizontal distance.

9. The trailer backup assist system of claim 8, wherein the controller calculates the first horizontal distance using a first equation:

d₁=d_v tan θ

wherein d₁ is the first horizontal distance, d_v is a vertical camera to target distance and θ

is an angle between a vertical extent of a rear member of the vehicle and the lower field extent.

10. The trailer backup assist system of claim 8, wherein the controller calculates the second horizontal distance using a second equation:

d₂=√

{square root over (d_a²+d_b²−

2d_ad_b cos γ

)}

wherein d₂ is the second horizontal distance, d_a is a distance from the camera to the intersection point, d_b is a camera to target midpoint distance, and γ

is an angle between the camera to target midpoint distance d_b and the camera to intersection point distance d_a.

11. The trailer backup assist system of claim 10, wherein angle γ

is calculated using a third equation;

12. The trailer backup assist system of claim 10, wherein the camera to target midpoint distance d_b is calculated using a fourth equation:

13. A method for calculating a horizontal camera to target distance, comprising the steps of:

providing a camera on board a vehicle and imaging a target located on a trailer aligned with the vehicle;

supplying a controller with image data from the camera and a user-obtained measurement; and

using the controller to calculate a first horizontal distance and a second horizontal distance;

wherein the first horizontal distance extends horizontally from the camera to an intersection point between the lower field extent and a centerline longitudinal axis of the target; and

wherein the second horizontal distance extends horizontally from the intersection point to a target midpoint.

14. The method of claim 13, wherein the user-obtained measurement comprises one of a target to ground distance and a draw bar drop measurement.

15. The method of claim 14, wherein the user-obtained measurement is inputted to the controller via a user-input device.

16. The method of claim 13, wherein the controller calculates the horizontal camera to target distance by summing the first horizontal distance and the second horizontal distance.

17. The method of claim 16, wherein the controller calculates the first horizontal distance using a first equation:

d₁=d_v tan θ

wherein d₁ is the first horizontal distance, d_v is a vertical camera to target distance and θ

is an angle between a vertical extent of a rear member of the vehicle and the lower field extent.

18. The method of claim 16, wherein the controller calculates the second horizontal distance using a second equation:

d₂=√

{square root over (d_a²+d_b²−

2d_ad_b cos γ

)}

wherein d₂ is the second horizontal distance, d_a is a distance from the camera to the intersection point, d_b is a camera to target midpoint distance, and γ

is an angle between the camera to target midpoint distance d_b and the camera to intersection point distance d_a.

19. The method of claim 18, wherein angle γ

is calculated using a third equation;

20. The method of claim 18, wherein the camera to target midpoint distance d_b is calculated using a fourth equation: