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

• US 8,019,513 B2
• Filed: 02/23/2007
• Issued: 09/13/2011
• 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): Tran; Khoi
• Assistant Examiner(s): Sample; Jonathan L
• Application Number:
  US11/678,558
• Publication Number:
  US 20070271013A1
• Time in Patent Office: 1,663 Days
• Field of Search: 701/41, 701/50, 701/300, 348/120, 382/104
• US Class Current: 701/50
• 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: G01C 11/00 Photogrammetry or videogrammetry, e.g. stereogrammetry; Photographic surveying

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. A preferential scan line profile in a search space about a 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. Alternatively, a position datum associated with a highest intensity value within the array of vector quantities can be selected as being indicative of a candidate position of a crop row. The candidate position is then identified as a preliminary row position if a variation in intensity level of the candidate scan line profile exceeds a threshold variation value.

Claims

1. A method of identifying a position of a crop row in a field 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, the candidate scan line profile comprising an array of vector quantities, each vector quantity comprising an intensity value and a corresponding position datum;

selecting the position datum associated with a corresponding highest intensity value within the array, as indicative of a candidate position of a crop row; and

identifying the candidate position as a preliminary row position if a variation in intensity level of the candidate scan line profile exceeds a threshold variation value.

2. The method of claim 1, wherein the defining includes defining the candidate scan line profile as a preferential scan line profile if the variation in intensity level exceeds a threshold variation value.

3. The method of claim 1, wherein the defining includes defining the candidate scan line profile as a preferential scan line profile if a variation in intensity level between a minimum intensity level and a maximum intensity level exceeds a threshold variation value.

4. The method of claim 1, wherein the defining includes:

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

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

5. The method of claim 1, wherein the selecting comprises sorting vector quantities in one of an ascending order and a descending order within the array based on the intensity value.

6. The method of claim 1, wherein the intensity value comprises a mean intensity value associated with a scan line segment within the collected image data.

7. The method of claim 1, wherein the selecting of the position datum comprises selecting the selected position datum as a preliminary row position if a variation in the intensity level of the candidate scan line profile exceeds a threshold value.

8. The method of claim 1, further comprising:

determining a weighted centroid of the intensity value within a region about the selected position datum; and

identifying a preliminary row position as a refined row position based on the weighted centroid.

9. The method of claim 1, further comprising disregarding vector quantities in the array within a defined neighborhood of at least one of the preliminary row position and a refined row position, wherein the defined neighborhood is commensurate with a predetermined row spacing between the two or more crops.

10. The method of claim 1, further comprising identifying an additional preliminary crop row position with a desired search space based on a predefined row spacing parameter with respect to at least one of the preliminary row position and a refined row position.

11. The method of claim 10, further comprising selecting an additional preliminary row position within the desired search space based on a vector quantity of the candidate scan line profile with a next highest intensity value as indicative of the additional preliminary row position.

12. The method of claim 1 further comprising, selecting an additional preliminary row position until a magnitude of a mean scan line intensity is less than a threshold value.

13. An apparatus for identifying a position of a crop row in a field comprising:

a processor; and

a memory unit communicatively connected to the processor and including;

computer code for collecting, via 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, the candidate scan line profile comprising an array of vector quantities, each vector quantity comprising an intensity value and a corresponding position datum;

computer code for selecting the position datum associated with a corresponding highest intensity value within the array, as indicative of a candidate position of a crop row; and

computer code for identifying the candidate position as a preliminary row position if a variation in the intensity level of the candidate scan line profile exceeds a threshold variation value.

14. The apparatus of claim 13, wherein the memory unit further comprises computer code for, defining the candidate scan line profile as a preferential scan line profile if the variation in the intensity level exceeds a threshold variation value.

15. The apparatus of claim 13, wherein the memory unit further comprises computer code for, defining the candidate scan line profile as a preferential scan line profile if a variation in the intensity level between a minimum intensity level and a maximum intensity level exceeds a threshold variation value.

16. The apparatus of claim 13, wherein the memory unit further comprises computer code for:

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

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

17. The apparatus of claim 13, wherein the memory unit further comprises computer code for, sorting vector quantities within the array in one of either an ascending and descending order, based on the intensity value in order to select the position datum.

18. The apparatus of claim 13, wherein the intensity value comprises a mean intensity value associated with a scan line segment within the collected image data.

19. The apparatus of claim 13, wherein the memory unit further comprises computer code for, selecting the position datum as a preliminary row position if a variation in the intensity level of the candidate scan line profile exceeds a threshold value.

20. The apparatus of claim 13, wherein the memory unit further comprises computer code for:

determining a weighted centroid of the intensity level within a region about the selected position datum; and

identifying a preliminary row position as a refined row position based on the weighted centroid.

21. The apparatus of claim 13, wherein the memory unit further comprises computer code for:

disregarding vector quantities in the array within a defined neighborhood of at least one of the preliminary row position and a refined row position, wherein the defined neighborhood is commensurate with a predetermined row spacing between the two or more crops.

22. The apparatus of claim 13, wherein the memory unit further comprises computer code for, identifying an additional preliminary crop row position with a desired search space based on a predefined row spacing parameter with respect to at least one of the preliminary row position and a refined row position.

23. The apparatus of claim 22, wherein the memory unit further comprises computer code for, selecting an additional preliminary row position within the desired search space based on the vector quantity of the candidate scan line profile with a next highest intensity value as indicative of the additional preliminary row position.

24. The apparatus of claim 13, wherein the memory unit further comprises computer code for, selecting an additional preliminary row position until a magnitude of a mean scan line intensity is less than a threshold value.

25. A computer program product, embodied on a computer-readable medium, for identifying a position of a crop row in a field comprising:

computer code for collecting, via 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, the candidate scan line profile comprising an array of vector quantities, each vector quantity comprising an intensity value and a corresponding position datum;

computer code for selecting the position datum, associated with a corresponding highest intensity value within the array, as indicative of a candidate position of a crop row; and

computer code for identifying the candidate position as a preliminary row position if a variation in intensity level of the candidate scan line profile exceeds a threshold variation value.

26. A system for identifying a position of a crop row in a field, the system comprising:

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

an imaging unit interface for receiving 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 selector configured to select a position datum associated with a corresponding highest intensity value within the array of vector quantities, as indicative of a candidate position of a crop row;

a confidence module configured to identify the candidate position as a preliminary row position if a variation in the intensity level of the candidate scan line profile exceeds a threshold variation 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.