Machine vision-based singulation verification system and method
A system and method for detecting multiple object conditions, such as side-by-side and overlapped objects, such as packages, on a conveyor. The system includes at least one machine vision system including at least one machine vision camera, at least one illumination subsystem and at least one machine vision computer. The illumination subsystem(s) is configured to illuminate a plurality of objects as they are conveyed past at least one field of view at an inspection station along a conveyor belt. Each machine vision camera is positioned to capture one or more images of the objects as the objects are conveyed past the field of view(s). Each machine vision computer is programmed to detect the presence of multiple object conditions by detecting and counting the number of edges appearing in an image of an object captured by one of the machine vision cameras. The method illuminates at least one object as it passes through the field of view, at which time at least one image of the object is captured. Next, each captured image is processed using a machine vision computer by windowing each parcel using a Region of Interest (ROI) and counting the number of edges appearing within the ROI. The presence of other than a single package condition is determined if the number of edges exceeds four.
1. A system for detecting the presence of overlapped objects on a conveyor belt conveying a plurality of objects, said system comprising:
at least one machine vision system including first and second machine vision cameras, first and second illumination sources, and at least one machine vision computer;
said first and second illumination sources configured to illuminate said plurality of objects as said objects are conveyed past a field of view at an inspection station along said conveyor belt, wherein said first illumination source illuminates said objects in a vertical direction and said second illumination source illuminates said objects in a horizontal direction, and wherein said first illumination source includes a lighting system configured to make said objects appear light against a substantially dark background, and said second illuminating source includes a lighting system configured to make a background light against said objects;
said first and second machine vision cameras positioned to capture images of said plurality of objects as said objects are conveyed past said field of view, and wherein said first machine vision camera is oriented to capture a first image of said objects in said field of view in the vertical direction, and said second machine vision camera oriented to capture a second image of said objects in said field of view in the horizontal direction;
said at least one machine vision computer programmed to detect the presence of multiple object conditions by detecting and counting a number of edges appearing in an image captured by said first or second machine vision camera; and
said at least one machine vision computer, for performing edge blob sortation on the image captured by said first or second machine vision camera.
2. The system of claim 1 , wherein said first lighting source includes at least one angled strobe light oriented on a side of said objects coinciding with said first machine vision camera.
3. The system of claim 2 , wherein said at least one angled strobe includes a xenon strobe.
4. The system of claim 1 wherein said first lighting source includes at least one high intensity light adjustably disposed in approximately the same plane as said first machine vision camera.
5. The system of claim 4 wherein said at least one high intensity light is a sodium vapor light.
6. The system of claim 4 further comprising a photodiode connected to said first lighting source, for controlling the intensity of said high intensity light.
7. The system of claim 1 , wherein the back light of the second lighting source is oriented on a side of said parcels opposite said second machine vision camera.
8. The system of claim 7 , wherein said back light includes an LED (light emitting diode) array.
9. The system of claim 7 , wherein said at least one machine vision camera includes a filter sensitive to a bandwidth of said second lighting source.
10. The system of claim 1 wherein said objects being conveyed and detected include packages.
11. The system of claim 1 , further including vertical and horizontal edge detectors, for detecting objects aligned within 15 degrees from a vertical axis and a horizontal axis, and further including a special outline detector, for detecting objects aligned between 15 degrees and 75 degrees from the vertical axis and the horizontal axis.
12. The system according to claim 1 , wherein said second lighting source includes a light emitting diode array.
13. A system for detecting the presence of overlapped parcels on a conveyor belt conveying a plurality of parcels, said system comprising:
at least one machine vision system including at least one machine vision camera, first and second illumination sources and at least one machine vision computer;
said first and second illumination sources configured to illuminate said plurality of parcels as said parcels are conveyed past a field of view at an inspection station along said conveyor belt, and wherein said first illumination source includes a lighting system configured to make said objects appear light against a substantially dark background, and said second illuminating source includes a lighting system configured to make a background light against said objects;
wherein said at least one machine vision camera includes first and second cameras, said first machine vision camera oriented to capture a first image of said parcels in said field of view in a vertical direction as said parcels are conveyed past said field of view, and said second machine vision camera oriented to capture a second image of said parcels in said field of view in a horizontal direction as said parcels are conveyed past said field of view;
said at least one machine vision computer programmed to detect the presence of multiple parcel conditions by detecting and counting a number of edges appearing in an image of said parcels captured by said first or second machine vision camera; and
said at least one machine vision computer, for performing edge blob sortation on the image of said parcel captured by said first or second machine vision camera.
14. The system of claim 13 , further including vertical and horizontal edge detectors, for detecting objects aligned within 15 degrees from a vertical axis and a horizontal axis, and further including a special outline detector, for detecting objects aligned between 15 degrees and 75 degrees from the vertical axis and the horizontal axis.