VEHICLE MANEUVERING AIDS

• US 20120200706A1
• Filed: 04/17/2012
• Published: 08/09/2012
• Est. Priority Date: 03/21/2007
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Greenwood, Jeremy John, Nicholls, Stephen, Crawford, Andrew Stephen Bell
• Granted Patent: US 9,156,496 B2
• Time in Patent Office: Days
• US Class Current: 348/148
• CPC Class Codes: B60R 1/003 for viewing trailer hitches
• CPC Class Codes: B60R 1/26 to the rear of the vehicle
• CPC Class Codes: B60R 1/28 with an adjustable field of view
• CPC Class Codes: B60R 1/30 providing vision in the non-visible spectrum, e.g. night or infrared vision
• CPC Class Codes: B60R 2300/101 using cameras with adjustable capturing direction
• CPC Class Codes: B60R 2300/108 using 'non-standard' camera systems, e.g. camera sensor used for additional purposes i.a. rain sensor, camera sensor split in multiple image areas
• CPC Class Codes: B60R 2300/301 combining image information with other obstacle sensor information, e.g. using RADAR/LIDAR/SONAR sensors for estimating risk of collision
• CPC Class Codes: B60R 2300/305 merging camera image with lines or icons
• CPC Class Codes: B60R 2300/50 characterised by the display information being shared, e.g. external display, data transfer to other traffic participants or centralised traffic controller
• CPC Class Codes: B60R 2300/802 for monitoring and displaying vehicle exterior blind spot views
• CPC Class Codes: B60R 2300/806 for aiding parking
• CPC Class Codes: B60R 2300/8086 for vehicle path indication
• CPC Class Codes: B60R 2300/8093 for obstacle warning
• CPC Class Codes: B60W 2050/143 Alarm means
• CPC Class Codes: B60W 50/14 Means for informing the driver, warning the driver or prompting a driver intervention
• CPC Class Codes: B62D 13/06 for backing a normally drawn trailer
• CPC Class Codes: B62D 15/021 Determination of steering angle
• 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: G01B 11/272 using photoelectric detection means
• CPC Class Codes: G06T 7/0008 checking presence/absence
• CPC Class Codes: G06T 7/20 : Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51
• CPC Class Codes: G06V 20/56 : exterior to a vehicle by using sensors mounted on the vehicle
• CPC Class Codes: G08G 1/16 : Anti-collision systems road vehicle drive control systems for predicting or avoiding probable or impending collision otherwise than by control of a particular sub-unit B60W30/08
• CPC Class Codes: G08G 1/166 : for active traffic, e.g. moving vehicles, pedestrians, bikes
• CPC Class Codes: G08G 1/167 : Driving aids for lane monitoring, lane changing, e.g. blind spot detection
• CPC Class Codes: G08G 1/168 : Driving aids for parking, e.g. acoustic or visual feedback on parking space
• CPC Class Codes: H04N 23/54 : Mounting of pick-up tubes, electronic image sensors, deviation or focusing coils
• CPC Class Codes: H04N 7/183 : for receiving images from a single remote source

Abstract

A vehicle 1 towing a trailer 4 is fitted with three video cameras 5, 6, 7 fitted to the rear of the vehicle and on each door mirror. A view from any camera can be presented to the driver on a display 11. A predicted trailer path, calculated in a computing unit 10, is also presented to the driver on the display 11 as guide lines overlaid on the camera view. The computing unit 10 is also configured to calculate a hitch angle by tracking the position of a trailer-mounted marker in the camera view.

Claims

1. A method of predicting a path of a trailer attached to a vehicle comprising the steps of:

measuring a vehicle steering angle;

obtaining first and second views from at least two rearward-looking, vehicle-mounted video cameras;

determining a trailer view from the first and second camera views;

displaying the trailer view on a screen visible to a driver;

determining a hitch angle, θ

_t, between the vehicle and trailer and using the trailer view;

calculating a predicted path of the trailer from the hitch angle and steering angle; and

displaying the predicted trailer path as an overlaid track on the trailer view.

2. The method of claim 1, further comprising the step of determining a hitch length, H, between an axle of the trailer and a point of attachment of the trailer to the vehicle and using H to calculate the predicted trailer path.

3. The method of claim 1, further comprising the step of calculating a turning radius R where R=H/θ

_t, where the trailer is predicted to follow the circumference of a circle of radius R and using R to calculate the predicted trailer path.

4. The method of claim 1, further comprising the steps of:

determining a hitch length, H, between an axle of the trailer and a point of attachment of the trailer to the vehicle;

determining a hitch angle, θ

_t, between the vehicle and trailer;

calculating a turning radius R where R=H/θ

_t, where the trailer is predicted to follow the circumference of a circle of radius R; and

using H, θ

_t, and R to calculate the predicted trailer path.

5. The method of claim 1, further comprising the steps of:

determining which of the first and second camera views shows the trailer; and

displaying the determined view on the screen.

6. The method of claim 1, further comprising the steps of:

tracking a marker associated with the trailer across a field of view of at least one of the rearward-looking video cameras; and

converting a vertical displacement of the marker in the field of view to an angular displacement to determine a pitch angle.

7. The method of claim 6 further comprising the steps of:

comparing the pitch angle with a reference value; and

if the pitch angle is within a predetermined range of the reference value wherein the trailer is likely to ground, generating a warning signal to the driver indicative of an imminent grounding event.

8. The method of claim 1, further comprising the step of determining a hitch angle, θ

_t, between the vehicle and trailer and using θ

_t to calculate the predicted trailer path.

9. The method of claim 8, wherein a hitch length H is determined by driving the vehicle-trailer combination in a circular path, while measuring a vehicle steering angle θ

_s, calculating the radius R of the circular path from θ

_s and knowledge of the dimensions of the vehicle, measuring a hitch angle θ

_t and calculating a hitch length H from the relationship H=Rθ

_t.

10. The method of claim 8 further comprising comparing the hitch angle to a stored value;

and

if the hitch angle is within a predetermined range of the stored value wherein the trailer is likely to jack-knife, generating a warning signal to the driver indicative of an imminent jack-knife event.

11. The method of claim 8, wherein the hitch angle θ

_t is determined by the steps of;

tracking a marker associated with the trailer across a field of view of at least one of the rearward-looking video cameras; and

converting a lateral displacement of the marker in the field of view to an angular displacement.

12. The method of claim 11 wherein the marker is placed on a centre-line of the trailer.

13. The method of claim 11 wherein the marker is placed offset from a centre-line of the trailer.

14. The method of claim 13 further comprising the steps of:

converting the lateral displacement of the marker to the angular displacement while the vehicle is traveling forward when the steering angle sensor outputs a value of zero for the steering angle to measure an angular offset displacement;

converting the lateral displacement of the marker to the angular displacement while the vehicle is traveling rearward to measure a target angular displacement; and

subtracting the angular offset displacement from the target angular displacement to determine the hitch angle.

15. The method of claim 14 further comprising the steps of:

converting the lateral displacement of the marker to the angular displacement while the vehicle is traveling forward when the steering angle sensor outputs a value of zero for the steering angle to remeasure the angular offset displacement; and

averaging the measured and remeasured angular offset displacements.

16. The method of claim 14 further comprising the steps of:

storing the angular offset displacement; and

recalling the stored angular offset displacement.

17. The method of claim 11 further comprising the step of selecting the marker on the trailer by an image processor of the vehicle.

18. The method of claim 17 further comprising the step of selecting a window on the trailer as the marker by an image processor of the vehicle.

19. The method of claim 17 further comprising the step of selecting an edge of the trailer as the marker by an image processor of the vehicle.

20. The method of claim 17 further comprising the step of displaying the marker on a display screen for driver confirmation that the selected marker is rigidly connected to the trailer.