Exception detection and handling in automated optical code reading systems

• US 8,939,369 B2
• Filed: 01/24/2012
• Issued: 01/27/2015
• Est. Priority Date: 01/24/2011
• Status: Active Grant

• Current Assignee: Datalogic Adc, Inc. (Datalogic S.p.A.)
• Original Assignee: Datalogic Adc, Inc. (Datalogic S.p.A.)
• Inventors: Olmstead, Bryan L., Svetal, Michael P.
• Primary Examiner(s): Frech, Karl D
• Application Number:
  US13/357,459
• Publication Number:
  US 20130020391A1
• Time in Patent Office: 1,099 Days
• Field of Search: 235/462.08, 235/462.11, 235/462.42, 235/462.43, 235/444, 235/438
• US Class Current: 235/438
• CPC Class Codes: G06K 7/10445 the record carriers being fixed to further objects, e.g. RFIDs fixed to packages, luggage, mail-pieces or work-pieces transported on a conveyor belt
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10762 Relative movement
• 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
• CPC Class Codes: G06V 10/145 Illumination specially adapted for pattern recognition, e.g. using gratings
• CPC Class Codes: G07G 1/0063 with means for detecting the geometric dimensions of the article of which the code is read, such as its size or height, for the verification of the registration

Abstract

An automated system for reading optical codes includes a conveyor system to automatically transport objects and an object measurement system positioned along the conveyor system to measure the transported objects. In one configuration, the object measurement system generates model data representing three-dimensional models of the objects; multiple image capture devices positioned along the conveyor system capture images as the objects are transported to enable an optical code reading system to read optical codes that are captured in the images. An exception identification system associates optical codes with the three-dimensional models to determine whether an exception has occurred.

Claims

1. An automated system for reading optical codes of objects, comprising:

a conveyor system configured to transport the objects through a view volume;

an object measurement system positioned along the conveyor system to measure the objects as the objects are transported by the conveyor system, the object measurement system operable to generate model data representing three-dimensional models of the objects;

an optical code reading system providing the view volume and including multiple image capture devices positioned along the conveyor system at different locations to provide different fields of view of the view volume, the optical code reading system operable to capture images as the objects are transported through the view volume and to read optical codes that are captured in the images, the optical code reading system operable to generate optical code data in response to reading the optical codes captured in the images; and

an exception identification system in communication with the optical code reading system and the object measurement system, the exception identification system operable to associate the optical code data with the three-dimensional models of the objects represented in the model data to determine whether an exception has occurred.

2. The system of claim 1, further comprising a security image capture device positioned along the conveyor system to capture security images of a scene in which the objects are present, the security image capture device operable to produce image data representing the security images of the scene.

3. The system of claim 2, further comprising:

an object annotation system configured to communicate with the security image capture device and the exception identification system, the object annotation system configured to produce from the image data annotated image data representing annotated images of the scene that include markings that indicate whether or not exceptions are associated with the objects in the scene, the object annotation system operable to communicate with the object measurement system, wherein the markings of the annotated images correspond to colored outlines of the three-dimensional models that are superimposed on the security images of the objects; and

a display screen operable to receive the annotated image data and display the annotated images of the scene.

4. The system of claim 1, wherein the object measurement system includes a vertical object sensor and a lateral object sensor.

5. The system of claim 4, wherein the vertical object sensor is a dual light curtain that bounds vertical sides of the view volume.

6. The system of claim 4, wherein the object measurement system includes an artificial illumination source that illuminates the objects to facilitate generation of footprint representations of the objects with the lateral object sensor.

7. The system of claim 6, wherein the artificial illumination source is configured to provide backlight illumination for the lateral object sensor to enable the lateral object sensor to generate silhouette footprint representations of the objects.

8. The system of claim 4, wherein the conveyor system includes first and second conveyors that are separated from each other to form a gap.

9. The system of claim 8, wherein the lateral object sensor includes a sensor element that is positioned directly above the gap formed between the first and second conveyors to provide a vertically-oriented non-tilted view plane for the lateral object sensor.

10. The system of claim 8, wherein the lateral object sensor includes a sensor element that is positioned below the first and second conveyors and directly under the gap to provide a vertically-oriented non-tilted view plane for the lateral object sensor.

11. The system of claim 8, further comprising a data capture device that houses at least part of the object measurement system and one or more of the image capture devices of the optical code reading system, the data capture device configured to form an arch over one or more of the first and second conveyors, the data capture device including a top portion along which a first element of the lateral object sensor is positioned, the lateral object sensor system including a second element positioned below one or more of the first and second conveyors.

12. The system of claim 11, wherein:

the lateral object sensor has a view plane provided by the first and second elements;

the data capture device is positioned along the first and second conveyors so that the first element of the lateral object sensor is directly above the gap between the first and second conveyors; and

the second element of the lateral object sensor is positioned directly below the gap and in-line with the first element so that the view plane of the lateral object sensor has a vertical, non-tilted orientation.

13. The system of claim 1, wherein the optical code reading system includes light directing optics that split the fields of view of the image capture devices into multiple portions directed to different areas of the view volume.

14. The system of claim 1, wherein the optical code reading system is operable to generate projection data for the optical codes captured in the images, the projection data representing back projection rays that project into the view volume and are associated with locations of the optical codes in the images, the automated system further comprising:

an optical code intersection system operable to receive the model data and the projection data and to determine whether the back projection rays generated by the optical code reading system intersect the three-dimensional models generated by the object measurement system, the exception identification system configured to associate the optical code data with the three-dimensional models of the objects based on intersection determinations of the optical code intersection system.

15. The system of claim 14, wherein the optical code intersection system is operable to determine whether the back projection rays intersect with the three-dimensional models after the objects exit the view volume.

16. The system of claim 14, wherein the optical code reading system is operable to calculate bounding boxes for the optical codes captured in the images and centroids of the bounding boxes, and wherein the optical code reading system uses the centroids to produce the back projection rays.

17. The system of claim 1, wherein the exception identification system is operable to identify one or more of:

a first exception type in which a three-dimensional model generated by the object measurement system does not have an associated optical code;

a second exception type in which different optical codes read by the optical code reading system are associated with a single three-dimensional model generated by the object measurement system;

a third exception type in which an optical code read by the optical code reading system is not associated with a three-dimensional model; and

a fourth exception type in which a single optical code read by the optical code reading system is associated with multiple three-dimensional models generated by the object measurement system.

18. The system of claim 1, wherein the exception identification system is operable to identify an exception type in which a difference between:

(a) a size of a three-dimensional model generated by the object measurement system, and (b) an expected size stored in a database and identified by an optical code associated with the three-dimensional model, is greater than a selected threshold.

19. The system of claim 1, wherein the exception identification system is operable to categorize exceptions according to exception types and to produce exception category identification information associated with the exceptions.

20. The system of claim 19, wherein the exception category identification information includes category labels corresponding to the exception types.

21. The system of claim 19, further comprising an exception handling system configured to receive the exception category identification information, the exception handling system operable to automatically determine how to resolve the exceptions based on the exception types.

22. The system of claim 21, wherein the exception handling system is configured to ignore exceptions of a first one of the exception types.

23. The system of claim 21, wherein the exception handling system is configured to automatically resolve exceptions of a first one of the exception types.

24. The system of claim 23, wherein:

an exception of the first exception type corresponds to an event in which different optical codes read by the optical code reading system are associated with a single three-dimensional model generated by the object measurement system, the different optical codes identifying object information stored in a database, and the object information including expected sizes of objects associated with the different optical codes; and

the exception handling system is configured to automatically resolve the exception of the first exception type by;

determining a sum of the expected sizes of the objects associated with the different optical codes;

comparing the sum of the expected sizes to a measured size of the single three-dimensional model generated by the object measurement system; and

identifying that a difference between the sum of the expected sizes and the measured size is below a selected threshold.

25. The system of claim 21, wherein the exception handling system is configured to determine that exceptions of a first one of the exception types are to be manually resolved.

26. The system of claim 25, wherein the exception handling system is configured to receive feedback information produced in response to a user manually resolving exceptions of the first exception type, and wherein the exception handling system is operable to use the feedback information to adapt how exceptions of the first exception type are resolved.

27. The system of claim 26, wherein the exception handling system is configured to automatically ignore exceptions of the first exception type in response to the user manually ignoring a selected number of exceptions of the first exception type.

28. The system of claim 21, further comprising a storage device configured to store information associated with exceptions that are resolved.

29. A method of identifying an exception in an automatic optical code reading system in which an object bearing an optical code is automatically moved along a path, comprising:

measuring the object as it moves along the path to generate a three-dimensional model of the object;

capturing an image of the object as it moves along the path and through a view volume, the image including a representation of the optical code;

reading the optical code based on analysis of the image; and

determining whether the optical code is associated with the three-dimensional model of the object to thereby identify whether an exception is associated with the object.

30. The method of claim 29, further comprising:

calculating a back projection ray for the optical code that corresponds to a correlation of a location of the representation of the optical code in the image to a number of three-dimensional coordinate points in the view volume;

computing an amount of time that has elapsed from the reading step to the determining step;

deriving a distance the object has traveled along the path during the amount of time that has elapsed; and

shifting the back projection ray by the distance the object has traveled to determine whether the back projection ray intersects the three-dimensional model.

31. The method of claim 30, wherein the determining step is performed after the object leaves the view volume.

32. The method of claim 29, wherein the three-dimensional model has a measured size, further comprising:

retrieving an expected object size stored in a database and associated with the optical code;

comparing the expected object size to the measured size to determine a difference therebetween;

identifying that an exception is associated with the object in response to the difference exceeding a selected threshold.

33. The method of claim 29, wherein the three-dimensional model has a measured size, further comprising:

determining that different optical codes are associated with the three-dimensional model thereby generating a multiple code exception;

retrieving multiple expected object sizes stored in a database and associated with the different optical codes;

summing the expected object sizes to generate a sum;

comparing the sum to the measured size of the three-dimensional model to determine a difference between the sum and the measured size; and

automatically resolving the multiple optical code exception in response to the difference being less than a selected threshold.