Vision guidance system and method for identifying the position of crop rows in a field

• US 7,904,218 B2
• Filed: 02/23/2007
• Issued: 03/08/2011
• Est. Priority Date: 05/18/2006
• Status: Active Grant

• Current Assignee: Nokia Corporation, Foster-Miller Incorporated (Thermo Fisher Scientific Incorporated)
• Original Assignee: Applied Perception, Inc. (Thermo Fisher Scientific Incorporated)
• Inventors: Batavia, Parag, Jochem, Todd, Ollis, Mark
• Primary Examiner(s): Zanelli; Michael J.
• Application Number:
  US11/678,548
• Publication Number:
  US 20070271012A1
• Time in Patent Office: 1,474 Days
• Field of Search: None
• US Class Current: 701/28
• CPC Class Codes: A01B 69/001 Steering by means of optical assistance, e.g. television cameras steering devices for road marking vehicles E01C23/163
• CPC Class Codes: A01D 41/1278 for automatic steering
• CPC Class Codes: G05D 1/0246 using a video camera in combination with image processing means

Abstract

A system and method of identifying a position of a crop row in a field, where an image of two or more crop rows is transmitted to a vision data processor. The vision data processor defines a candidate scan line profile for a corresponding heading and pitch of associated with a directional movement of a vehicle, for example, traversing the two or more crop rows. The candidate scan line profile comprises an array of vector quantities, where each vector quantity comprises an intensity value and a corresponding position datum. A preferential scan line profile in a search space about the candidate scan line profile is determined, and the candidate scan line profile is identified as a preferential scan line profile for estimating a position (e.g., peak variation) of one or more crop rows if a variation in the intensity level of the candidate scan line profile exceeds a threshold variation value.

Claims

1. A method comprising:

collecting, via an imaging unit, image data of two or more crop rows;

defining a candidate scan line profile for a corresponding heading and pitch of directional movement associated with the imaging unit and relative to the two or more crop rows;

searching for a preferential scan line profile in an angular search space about the candidate scan line profile; and

identifying the candidate scan line profile as a preferential scan line profile for estimating a position of at least one of the two or more crop rows if a variation in an intensity level of the candidate scan line profile exceeds a threshold variation value,

wherein the identifying further comprises;

determining a sum of absolute differences for the candidate scan line profile; and

identifying the candidate scan line profile as a preferential scan line profile if the sum of the absolute differences exceeds a threshold value.

2. The method of claim 1, wherein the candidate scan line profile comprises an array of vector quantities, each vector quantity comprising an intensity value and a corresponding position datum.

3. The method of claim 2, wherein the defining of the candidate scan line profile comprises virtually aligning a plurality of scan line segments to the two or more crop rows, the array of vector quantities derived therefrom.

4. The method of claim 2, wherein the intensity value comprises a mean intensity value associated with a scan line segment within the collected image data.

5. The method of claim 1, wherein the angular search space is defined by the corresponding pitch and heading of directional movement associated with the imaging unit and relative to the two or more crop rows.

6. The method of claim 1 further comprising, identifying the candidate scan line profile as a preferential scan line profile if the variation in the intensity level between a minimum intensity level and a maximum intensity level exceeds the threshold variation value.

7. The method of claim 6, wherein the minimum intensity level corresponds to an area between each of the two or more crop rows and the maximum intensity level corresponds to a center of one of the two or more crop rows.

8. The method of claim 1 further comprising, normalizing an intensity of the collected image data following the collecting of the image data.

9. The method of claim 8 further comprising:

defining a virtual, substantially horizontal plane in the collected image data; and

subtracting out the virtual, substantially horizontal plane to reduce image intensity variation throughout the collected image data.

10. The method of claim 8, wherein the intensity of the collected image data indicates one of either an illumination value, a brightness value, and a luminance value of at least one pixel which at least in part comprises the collected image data.

11. An apparatus comprising:

a processor; and

a memory unit communicatively connected to the processor and including;

computer code executable by the processor for receiving, from an imaging unit, image data of two or more crop rows;

computer code executable by the processor for defining a candidate scan line profile for a corresponding heading and pitch of directional movement associated with the imaging unit and relative to the two or more crop rows;

computer code executable by the processor for searching for a preferential scan line profile in an angular search space about the candidate scan line profile; and

computer code executable by the processor for identifying the candidate scan line profile as a preferential scan line profile for estimating a position of at least one of the two or more crop rows if a variation in an intensity level of the candidate scan line profile exceeds a threshold variation value,

wherein the computer code executable by the processor for identifying the candidate scan line profile comprises computer code executable by the processor for;

determining a sum of absolute differences for the candidate scan line profile; and

identifying the candidate scan line profile as the preferential scan line profile if the sum of the absolute differences exceeds a threshold value.

12. The apparatus of claim 11, wherein the candidate scan line profile comprises an array of vector quantities, each vector quantity comprising an intensity value and a corresponding position datum.

13. The apparatus of claim 12, wherein the memory unit further comprises computer code executable by the processor for, virtually aligning a plurality of scan line segments to the two or more crop rows, the array of vector quantities derived therefrom, in order to define the candidate scan line profile.

14. The apparatus of claim 12, wherein the intensity value comprises a mean intensity value associated with a scan line segment within the collected image data.

15. The apparatus of claim 11, wherein the angular search space is defined by the corresponding pitch and heading of directional movement associated with the imaging unit and relative to the two or more crop rows.

16. The apparatus of claim 11, wherein the memory unit further comprises computer code executable by the processor for, identifying the candidate scan line profile as a preferential scan line profile if the variation in the intensity level between a minimum intensity level and a maximum intensity level exceeds the threshold variation value.

17. The apparatus of claim 16, wherein the minimum intensity level corresponds to an area between each of the two or more crop rows and the maximum intensity level corresponds to a center of one of the two or more crop rows.

18. The apparatus of claim 11, wherein the memory unit further comprises computer code executable by the processor for, normalizing an intensity of the collected image data following the collecting of the image data.

19. The apparatus of claim 18, wherein the memory unit further comprises computer code executable by the processor for:

defining a virtual, substantially horizontal plane in the collected image data; and

subtracting out the virtual, substantially horizontal plane to reduce image intensity variation throughout the collected image data.

20. The apparatus of claim 18, wherein the intensity of the collected image data indicates one of either an illumination value, a brightness value, and a luminance value of at least one pixel which at least in part comprises the collected image data.

21. A computer program product, embodied on a computer-readable medium, comprising:

computer code for collecting, from an imaging unit, image data of two or more crop rows;

computer code for defining a candidate scan line profile for a corresponding heading and pitch of directional movement associated with the imaging unit and relative to the two or more crop rows;

computer code for searching for a preferential scan line profile in an angular search space about the candidate scan line profile; and

computer code for identifying the candidate scan line profile as a preferential scan line profile for estimating a position of at least one of the two or more crop rows if a variation in an intensity level of the candidate scan line profile exceeds a threshold variation value,

wherein the computer code for identifying the candidate scan line profile comprises computer code for;

determining a sum of absolute differences for the candidate scan line profile; and

identifying the candidate scan line profile as the preferential scan line profile if the sum of the absolute differences exceeds a threshold value.

22. A system comprising:

an imaging unit configured to collect image data of two or more crop rows;

an imaging unit interface configured to receive the collected image data;

a definer communicatively connected to the imaging unit interface configured to define a candidate scan line profile for a corresponding heading and pitch of the imaging unit, the candidate scan line profile comprising an array of vector quantities, each vector quantity comprising an intensity value and a corresponding position datum;

a search engine configured to search for a preferential scan line profile in an angular search space about the candidate scan line profile, the search space defined by the corresponding pitch and heading of the imaging unit;

the search engine identifying the candidate scan line profile as a preferential scan line profile for estimating a position of one or more crop rows if a variation in the intensity level of the candidate scan line profile exceeds a threshold variation value, the identifying of the candidate scan line profile comprising;

determining a sum of absolute differences for the candidate scan line profile; and

identifying the candidate scan line profile as the preferential scan line profile if the sum of the absolute differences exceeds a threshold value; and

a control port configured to output directional movement instructions to a vehicle steering controller, the directional movement instructions derived from the preferential scan line profile.