Method and system for optoelectronic detection and location of objects

• US 8,927,917 B2
• Filed: 07/26/2012
• Issued: 01/06/2015
• Est. Priority Date: 06/15/2007
• Status: Active Grant

• Current Assignee: Cognex Corporation
• Original Assignee: Cognex Corporation
• Inventors: Silver, William M.
• Primary Examiner(s): LEE, JOHN R
• Application Number:
  US13/558,828
• Publication Number:
  US 20130039536A1
• Time in Patent Office: 894 Days
• Field of Search: 250/208.1, 348/135, 348/142, 382/124, 382/312, 382/103, 382/107, 382/321, 382/323, 700/258, 700/259, 702/189
• US Class Current: 250/208.1
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• CPC Class Codes: G06T 2207/30108 Industrial image inspection
• 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: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80

Abstract

Disclosed are methods and systems for optoelectronic detection and location of moving objects. The disclosed methods and systems capture one-dimensional images of a field of view through which objects may be moving, make measurements in those images, select from among those measurements those that are likely to correspond to objects in the field of view, make decisions responsive to various characteristics of the objects, and produce signals that indicate those decisions. The disclosed methods and systems provide excellent object discrimination, electronic setting of a reference point, no latency, high repeatability, and other advantages that will be apparent to one of ordinary skill in the art.

Claims

1. A computer program product comprising instructions for a data processing apparatus to control an apparatus for optically providing information describing an object in motion relative to a field of view, such that the object passes through the field of view, the product tangibly embodied in a non-transitory computer readable medium, the instructions being operable to cause the data processing apparatus to:

receive data representing a plurality of one-dimensional images of the field of view, wherein

the images are oriented approximately parallel to the direction of motion; and

a plurality of the images correspond to a plurality of positions of the object relative to the field of view; and

calculate information describing the object based on a plurality of the images.

2. The product of claim 1, wherein the information describing the object comprises knowledge responsive to object presence in the field of view.

3. The product of claim 1, wherein the object crosses a reference point at a reference time and the information describing the object comprises an estimate of the reference time.

4. The product of claim 3, wherein the estimate of the reference time is determined by predicting the reference time.

5. The product of claim 3, wherein the product further comprises instructions to cause the data processing apparatus to provide a value responsive to the estimate of the reference time for consumption by an input/output module.

6. A system using the product recited in claim 3, further comprising a signaling process that produces a signal that indicates the estimate of the reference time by occurring at a signal time that is responsive to the estimate of the reference time.

7. The system of claim 6, further comprising an electronic human-machine interface, and wherein the signal time is adjusted in response to the human-machine interface.

8. The system of claim 6, wherein there is no latency between the reference time and the signal time.

9. A system using the product recited in claim 3, further comprising

an example object;

and

a setup signal that indicates that the example object is placed in the field of view at a setup position;

and wherein the reference point is set responsive to the example object, the setup signal, and the setup position.

10. The system of claim 9, further comprising a signaling process that produces a signal responsive to the information describing the object, wherein the signal occurs at a time when the object crosses the setup position.

11. The system of claim 9, further comprising a signaling process that produces a signal responsive to the information describing the object, and wherein the signal occurs at a time when the object is upstream from the setup position.

12. A system using the product recited in claim 3, further comprising

a test object;

and

a human-machine interface comprising an indicator that indicates a detection state that includes at least one of;

the test object is detected upstream from the reference point;

the test object is detected downstream from the reference point; and

the test object is not detected.

13. A system using the product recited in claim 3, further comprising a linear optical sensor having a one-dimensional array of photoreceptors that makes light measurements in the field of view.

14. The product of claim 3, wherein calculating the information describing the object further comprises:

calculating image measurements based on a plurality of the images;

selecting as object measurements, ones of the image measurements calculated responsive to the object; and

calculating the information describing the object based on the object measurements.

15. The product of claim 14, wherein at least one of the image measurements are responsive to object presence in the field of view and the information describing the object comprises knowledge responsive to object presence in the field of view.

16. The product of claim 14 wherein

the object crosses a reference point at a reference time;

at least a portion of the image measurements are responsive to object position in the field of view; and

wherein the product further comprises instructions to cause the data processing apparatus to select the object measurement, ones of the image measurements that are responsive to object position and

calculate an estimate of the reference time based on the object position as the information describing the object.

17. The product of claim 16, wherein

a capture process produces a plurality of capture times, each capture time being responsive to a time at which a corresponding image was captures;

and

a decision process is responsive to at least one of the capture times.

18. The product of claim 17, wherein the decision process comprises fitting a curve to points comprising a plurality of the capture times and corresponding object measurements that are selected from among the image measurements that are responsive to object position in the field of view.

19. The product of claim 16, further comprising an electronic human-machine interface, and wherein the reference point is adjusted in response to the human-machine interface.

20. The product of claim 16, further comprising a signaling process that produces a signal responsive to the information describing the object, and wherein the signal indicates the information describing the object by occurring at a signal time that is responsive to the estimate of the reference time.

21. The product of claim 20, further comprising an electronic human-machine interface, and wherein the signal time is adjusted in response to the human-machine interface.

22. The product of claim 20, wherein there is no latency between the reference time and the signal time.

23. The product of claim 16, wherein the decision process determines the estimate of the reference time by predicting the reference time.