METHOD FOR THE OPTICAL IDENTIFICATION OF OBJECTS IN MOTION

• US 20140029796A1
• Filed: 02/20/2012
• Published: 01/30/2014
• Est. Priority Date: 02/28/2011
• Status: Active Grant

• Current Assignee: Datalogic IP Tech S.r.l. (Datalogic S.p.A.)
• Original Assignee: Datalogic IP Tech S.r.l. (Datalogic S.p.A.)
• Inventors: Fiorini, Daniele, Owen, Ricky Darrell, Pellegrino, Luigi
• Granted Patent: US 9,349,047 B2
• Time in Patent Office: Days
• US Class Current: 382/103
• CPC Class Codes: G06K 7/10861 sensing of data fields affixed to objects or articles, e.g. coded labels postal sorting B07C3/14, conveying articles B65G47/48

Abstract

The method includes the steps of acquiring, by at least one camera having a predetermined magnification ratio, at least one image containing at least one coded information and at least one object and properly associating the coded information with the at least one object on the basis of the position of the coded information and of the at least one object along an advancing direction with respect to a fixed reference system. The above-mentioned position of the coded information is determined starting from the position of the coded information within the image acquired by the camera and on the basis of the distance of the coded information from the camera. Such a distance is in turn determined on the basis of the magnification factor of a reference physical dimension detected at a surface of the object or of the coded information.

Claims

1. A method for the optical identification of objects in motion, comprising the following steps:

acquiring, by at least one camera having, at least during such an acquisition, a respective predetermined magnification ratio, at least one image of a predetermined detection area, said at least one image containing at least one portion of at least one object travelling through the detection area along a predetermined advancing direction;

determining the position of said at least one portion of said at least one object along the predetermined advancing direction with respect to a predetermined reference system;

detecting, in said at least one image or in at least one subsequent image containing said at least one portion of at least one object, at least one coded information travelling through the detection area along the predetermined advancing direction, said detection being carried out, respectively, by said at least one camera or by a distinct camera having a predetermined relative position with respect to said at least one camera and, at least during the acquisition of said at least one image or of said at least one subsequent image, a respective predetermined magnification ratio;

reading said at least one coded information;

determining the position of at least one portion of said at least one coded information along the predetermined advancing direction within the image;

detecting, by said at least one camera or said at least one distinct camera, at least one reference physical dimension belonging to at least one surface portion of said at least one object or of said at least one coded information;

determining the distance of said at least one surface portion from said at least one camera and, if provided, from said at least one distinct camera on the basis of said at least one reference physical dimension and of the magnification ratio of the camera by which said at least one reference physical dimension has been detected;

determining the position of said at least one portion of coded information along the predetermined advancing direction with respect to the predetermined reference system on the basis of said distance and of the position of said at least one portion of said at least one coded information along the predetermined advancing direction within the image;

associating said at least one coded information with a respective object travelling through the detection area when said at least one coded information is detected, said association being made on the basis of said position of said at least one portion of said at least one object with respect to the predetermined reference system and of said position of said at least one portion of said at least one coded information with respect to the predetermined reference system.

2. The method according to claim 1, wherein the step of detecting at least one reference physical dimension comprises the steps of:

determining the displacement of said at least one object along said advancing direction;

determining the maximum size of said at least one object along said advancing direction on the basis of said displacement.

3. The method according to claim 2, wherein the step of determining the maximum size of said at least one object along said advancing direction comprises the following steps:

determining the position of a first significant contrast variation along said advancing direction within said at least one image;

determining the number of pixels of said at least one image of said at least one camera occupied by said at least one object on the basis of the position of said first significant contrast variation.

4. The method according to claim 2, wherein said at least one image entirely contains said at least one object and the step of determining the maximum size of said at least one object along said advancing direction comprises the following steps:

determining the position of a first significant contrast variation and of a last significant contrast variation along said advancing direction within said at least one image;

determining the number of pixels of said at least one image occupied by said at least one object on the basis of the positions of said first significant contrast variation and said last significant contrast variation.

5. The method according to claim 1, wherein said at least one reference physical dimension is defined by a known dimension of a logo or different graphical element applied onto said at least one object.

6. The method according to claim 1, wherein said at least one coded information has a predetermined optical resolution and wherein the step of detecting at least one reference physical dimension comprises the step of determining the physical dimension of said at least one coded information along at least one characteristic direction.

7. The method according to claim 6, wherein the step of determining the physical dimension of said at least one coded information comprises the following steps:

determining the position of a first significant contrast variation along said at least one characteristic direction;

determining the number of pixels of said at least one image of said at least one camera or of said at least one distinct camera occupied by said coded information starting from the position of said first significant contrast variation and on the basis of said predetermined optical resolution.

8. The method according to claim 6, wherein said at least one coded information is a linear optical code and the step of determining the physical dimension of said at least one coded information comprises the step of measuring at least one element of said optical code along said at least one characteristic direction.

9. The method according to claim 6, wherein said at least one coded information is an optical code whose content extends along at least two predetermined orthogonal directions and the step of determining the physical dimension of said at least one coded information comprises the step of determining the dimensions of said optical code along at least one of said at least two predetermined orthogonal directions.

10. The method according to claim 8, wherein said optical code belongs to a predetermined symbology and said at least one reference physical dimension is determined on the basis of said predetermined symbology.

11. The method according to claim 1, wherein the step of determining the position of said at least one portion of said at least one object comprises the steps of:

detecting the instant at which said at least one object travels through a predetermined detection position;

determining the displacement of said at least one object along said advancing direction.

12. The method according to claim 11, wherein the step of determining the displacement of said at least one object comprises the steps of:

comparing the position of said at least one portion of said at least one image in at least two acquisitions;

calculating the displacement of said at least one object on the basis of said comparison.

13. The method according to claim 1, further comprising the step of detecting the distance of said at least one object by a specific distance measuring device.

14. The method according to claim 1, further comprising the following steps:

determining the position of said at least one object along two orthogonal directions within said at least one image;

determining the footprint of said at least one object in a plane with respect to said predetermined reference system on the basis of the position of said at least one object along said two orthogonal directions and of said distance.

15. The method according to claim 14, further comprising the step of determining the volume of said at least one object on the basis of said footprint and of said distance.

16. The method according to any claim 1, wherein said at least one camera is arranged so as to frame said at least one object from above the object and said at least one distinct camera is arranged so as to frame said at least one object from any of its sides.

17. The method according to claim 1, wherein said at least one camera and, if provided, said at least one distinct camera, is arranged so that its optical axis is orthogonal to said advancing direction.

18. The method according to claim 17, wherein said at least one image is acquired by said at least one camera when said at least one object is at said optical axis.

19. The method according to claim 18, comprising the steps of:

determining the distance of a plurality of points of said at least one surface portion;

determining a possible rotation angle between the optical axis of said at least one camera and the surface portion on the basis of the distance of said plurality of points.

20. The method according to claim 19, wherein the distance of said plurality of points is determined on the basis of the analysis of a perspective deformation of said at least one coded information.

21. The method according to claim 19, further comprising the following steps:

determining the position of said at least one object along two orthogonal directions within said at least one image;

determining the footprint of said at least one object in a plane with respect to said predetermined reference system on the basis of the position of said at least one object along said two orthogonal directions and of said distance;

wherein said possible rotation angle is determined on the basis of the analysis of said footprint.