AGRICULTURAL ARTICLE INSPECTION APPARATUS AND METHOD EMPLOYING SPECTRAL MANIPULATION TO ENHANCE DETECTION CONTRAST RATIO

• US 20020008055A1
• Filed: 12/14/1999
• Published: 01/24/2002
• Est. Priority Date: 03/26/1999
• Status: Active Grant

• Current Assignee: Key Technology, Inc. (Duravant LLC)
• Original Assignee: Key Technology, Inc. (Duravant LLC)
• Inventors: LEIDECKER, CLIFF J., KALAYEH, HOOSHMAND M., EWAN, JAMES, SQUYERS, H. PARKS, CAMPBELL, DUNCAN B.
• Granted Patent: US 6,410,872 B2
• Time in Patent Office: Days
• US Class Current: 209/577
• CPC Class Codes: B07C 5/3422 using video scanning devices, e.g. TV-cameras
• CPC Class Codes: G01N 2021/8466 Investigation of vegetal material, e.g. leaves, plants, fruits
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G01N 21/85 Investigating moving fluids or granular solids
• CPC Class Codes: Y10S 209/938 Illuminating means facilitating visual inspection

Abstract

A sorting system (110) conveys articles, such as peaches (114) on a conveyor belt (112) past an inspection zone (126) that is lighted by an illumination source (90) radiating a number of emission peaks over visible and infrared portions of the spectrum. The illumination source generates the radiation from an Indium Iodide lamp (92) that is reflected off a parabolic reflector (94) and through a “soda straw” collimator (100) to illuminated the peaches. A detector system (118) employs line scanning visible and infrared cameras (142, 140) to sense visible and IR wavelength reflectance values for the peach meat (124) and peach pit or pit fragments (126). Various image processing and analysis methologies, such as subtraction, ratio, logarithmic, regression, combination, angle, distance, and shape may be employed to enhance the image contrast and classify the resulting data for sorting the peaches. Employing subtraction also cancels “glint” caused by specular reflections of the illumination source off the peaches and into the cameras.

Claims

1. A method of sorting articles that are moved past an inspection zone, comprising:

illuminating the articles in the inspection zone with visible and infrared radiation;

sensing the visible and infrared radiation reflected from the articles in the inspection zone and generating visible and infrared image data;

extracting feature data from the visible and infrared image data;

classifying the feature data into class categories; and

separating the articles into acceptable articles and unacceptable articles in response to the class categories.

2. The method of claim 1 in which the acceptable articles include peaches, and the unacceptable articles include at least one of peach pits and pit fragments.

3. The method of claim 1 in which the illuminating includes providing an Indium Iodide high-intensity discharge lamp or a Helium plasma discharge lamp.

4. The method of claim 1 in which the sensing includes sensing the visible and infrared radiation with a wavelength-selective camera system.

5. The method of claim 1 in which the extracting and classifying are carried out by at least one of a lookup table and a computer program.

6. The method of claim 1 in which extracting the feature data includes processing the visible and infrared data with a mathematical operation including at least one of a subtraction, a ratio, a log-ratio, a linear combination, a principal component transform, and a regression function.

7. The method of claim 1 in which classifying the feature data includes calculating a statistical distance between clusters of the feature data.

8. The method of claim 1 in which classifying the feature data includes calculating at least one of a value, a mean, a variance, and a shape of clusters of the feature data.

9. An article sorting system that conveys the articles on a conveyor belt and past an inspection zone, comprising:

an illumination system emitting visible and infrared radiation for illuminating the articles in the inspection zone;

a detector system for sensing the visible and infrared radiation reflected from the articles in the inspection zone and generating visible and infrared image data;

a processor extracting features from the visible and infrared image data and classifying the features into class categories; and

a sorter responsive to the class categories for separating the articles into acceptable articles and unacceptable articles.

10. The system of claim 9 in which the acceptable articles include peaches, and the unacceptable articles include at least one of peach pits and pit fragments.

11. The system of claim 9 in which the illumination system includes at least one high-intensity discharge lamp that emits the visible and infrared radiation to illuminate the inspection zone.

12. The system of claim 9 in which the detector system senses the visible and infrared radiation with a wavelength-selective beam splitter-based camera or a beam splitter and two cameras.

13. The system of claim 9 in which the detector system senses the visible radiation with at least one line scanning wavelength-selective detector array-based camera.

15. The system of claim 9 in which the processor employs a lookup table for processing a difference between the visible image data and the infrared image data.