Object sorting system
First Claim
1. An object sorting device for solid objects that are presented in a limited plurality of allowed orientations in a plane with respect to a longitudinal axis in said plane, said device comprising:
- means for moving said objects in a direction along said longitudinal axis;
means for scanning successive objects each in a raster format to derive a raster waveform of each object;
means for binarizing the waveform of an object into a two-dimensional array of binary pixels comprising rows along the direction of said longitudinal axis and columns transverse to said longitudinal axis;
feature extraction means for extracting selected features from the two-dimensional binary array to produce a one-dimensional array comprising a plurality of elements each representative of the information content of a corresponding said column of binary pixels, said feature extraction means comprising run counting means for counting runs of successive identical elements of said one-dimensional array and for outputting only those runs having a predetermined minimum length at least equal to two to represent the selected features;
means fed by said feature extraction means for deriving a one-dimensional reference array from the scanning of a plurality of reference objects;
means for storing said reference array; and
comparison means receiving the output from said feature extraction means and said storage means for comparing within a predetermined tolerance the one-dimensional array of an unknown object with said one-dimensional reference array to produce a binary object sorting signal for sorting objects in an undesired orientation from said track.
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Abstract
Object sorting systems are known which use a vision based system programmed by an operator who selects those features of the object which will be used in the sorting test. In the invention, detailed feature selection by a human programmer is avoided, the features being selected automatically in a system which is shown examples of the desired and undesired objects. Typically, a linear array camera 5 scans the objects 18 in a rectangular raster, created by the motion of the object along a track 1 and in contact with a fence 2, to generate a binarized picture of the object comprising rows and columns of binary picture elements (pixels). In a learning mode, a master set of features is derived as a reference set of distinguishable columns of the picture. In the sorting mode, the corresponding set of columns of an unknown object are compared with the reference set to determine acceptance or rejection of the object.
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Citations
17 Claims
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1. An object sorting device for solid objects that are presented in a limited plurality of allowed orientations in a plane with respect to a longitudinal axis in said plane, said device comprising:
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means for moving said objects in a direction along said longitudinal axis; means for scanning successive objects each in a raster format to derive a raster waveform of each object; means for binarizing the waveform of an object into a two-dimensional array of binary pixels comprising rows along the direction of said longitudinal axis and columns transverse to said longitudinal axis; feature extraction means for extracting selected features from the two-dimensional binary array to produce a one-dimensional array comprising a plurality of elements each representative of the information content of a corresponding said column of binary pixels, said feature extraction means comprising run counting means for counting runs of successive identical elements of said one-dimensional array and for outputting only those runs having a predetermined minimum length at least equal to two to represent the selected features; means fed by said feature extraction means for deriving a one-dimensional reference array from the scanning of a plurality of reference objects; means for storing said reference array; and comparison means receiving the output from said feature extraction means and said storage means for comparing within a predetermined tolerance the one-dimensional array of an unknown object with said one-dimensional reference array to produce a binary object sorting signal for sorting objects in an undesired orientation from said track. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification