Method of and apparatus for detecting objects in an assembly line
First Claim
1. A method of detecting the presence of an object moving along an assembly line among a succession of objects and which objects have at least two identifying features thereon, comprising:
- obtaining an image of the first identifying feature of one of the objects constituted by a plurality of voltage signals of more than two different voltages;
choosing a first threshold level voltage for the first identifying feature of said one object;
classifying the signals of said plurality of voltage signals for said first identifying feature of said one object into signals greater than the first threshold level voltage and signals less than the first threshold level voltage;
forming from said thus classified signals a monochrome image;
comparing said monochrome image with a pre-memorized image of the first identifying feature constituted by a plurality of voltage signals for determining whether the monochrome image corresponds to the pre-memorized image;
when said image of said first identifying feature corresponds with the pre-memorized image, designating the threshold level voltage at which the correspondence occurs as matching threshold level voltage An ;
obtaining an image of the second identifying feature of said one object constituted by a plurality of voltage signals of more than two different voltages;
calculating a target threshold level voltage Bnt for the second identifying feature of said one object according the expression;
space="preserve" listing-type="equation">B.sub.nt =f(A.sub.n *, B.sub.n-1 *, A.sub.n) where An * is the average matching threshold level voltage for the first identifying features of preceding objects in the succession and Bn-1 * is the average matching threshold level voltage for the second identifying features of the preceding objects in the succession;
classifying the signals of said plurality of voltage signals for said second identifying feature into signals greater than the target threshold level voltage and signals less than the target threshold level voltage;
forming from said thus classified signals a monochrome image of second identifying feature;
comparing said monochrome image of the second identifying feature with a pre-memorized image of the second identifying feature constituted by a plurality of voltage signals for determining whether the monochrome image of the second identifying feature corresponds to the pre-memorized image of the second identifying feature;
when said image of said second identifying feature corresponds with the pre-memorized image, designating the threshold level voltage at which correspondence occurs as matching threshold level voltage Bn ;
obtaining an image of the first identifying feature of the next succeeding object and carrying out the steps of choosing a first threshold level voltage, classifying the signals, forming the monochrome image, and comparing the image for the last-mentioned first identifying feature to obtain a matching threshold level voltage An+1 for said last mentioned first identifying feature,calculating a target threshold level voltage Bn+1)T for the second identifying feature on said next succeeding object according to the expression;
space="preserve" listing-type="equation">B.sub.n+1)T =f(A.sub.n+1 *, B.sub.n *, A.sub.n+1) where An+1 * is the average matching threshold level voltage for the first identifying features of the succession of objects including matching threshold level voltage An+1, Bn * is the average matching threshold level voltage for the second identifying features of the succession of objects including matching threshold level voltage Bn ; and
obtaining an image of the second identifying feature of the next succeeding object and carrying out the steps of classifying the signals using the newly calculated target threshold level voltage, forming the monochrome image and comparing the image for the last mentioned second identifying feature.
3 Assignments
0 Petitions
Accused Products
Abstract
A method and apparatus for identifying marking holes in an object moving along a conveyor or the like, in which television image signals of the identifying marking holes are classified into signals above and below a threshold level voltage and then made into a monochrome image of the identifying marking holes which is then compared with a pre-memorized image of the marking hole. The invention involves a particular way of selecting the threshold level voltages by using a threshold level voltage from among threshold level voltages used to identify the marking holes in preceding objects according to the frequency of occurrence of the threshold level voltages, and for the threshold level voltage of the second identifying marking hole, initially calculating a target threshold level voltage, and then modifying it if necessary by reference to threshold level voltages used to identify the second marking hole in preceding objects, so as to make the identification of the second hole quicker.
17 Citations
8 Claims
-
1. A method of detecting the presence of an object moving along an assembly line among a succession of objects and which objects have at least two identifying features thereon, comprising:
-
obtaining an image of the first identifying feature of one of the objects constituted by a plurality of voltage signals of more than two different voltages; choosing a first threshold level voltage for the first identifying feature of said one object; classifying the signals of said plurality of voltage signals for said first identifying feature of said one object into signals greater than the first threshold level voltage and signals less than the first threshold level voltage; forming from said thus classified signals a monochrome image; comparing said monochrome image with a pre-memorized image of the first identifying feature constituted by a plurality of voltage signals for determining whether the monochrome image corresponds to the pre-memorized image; when said image of said first identifying feature corresponds with the pre-memorized image, designating the threshold level voltage at which the correspondence occurs as matching threshold level voltage An ; obtaining an image of the second identifying feature of said one object constituted by a plurality of voltage signals of more than two different voltages; calculating a target threshold level voltage Bnt for the second identifying feature of said one object according the expression;
space="preserve" listing-type="equation">B.sub.nt =f(A.sub.n *, B.sub.n-1 *, A.sub.n)where An * is the average matching threshold level voltage for the first identifying features of preceding objects in the succession and Bn-1 * is the average matching threshold level voltage for the second identifying features of the preceding objects in the succession; classifying the signals of said plurality of voltage signals for said second identifying feature into signals greater than the target threshold level voltage and signals less than the target threshold level voltage; forming from said thus classified signals a monochrome image of second identifying feature; comparing said monochrome image of the second identifying feature with a pre-memorized image of the second identifying feature constituted by a plurality of voltage signals for determining whether the monochrome image of the second identifying feature corresponds to the pre-memorized image of the second identifying feature; when said image of said second identifying feature corresponds with the pre-memorized image, designating the threshold level voltage at which correspondence occurs as matching threshold level voltage Bn ; obtaining an image of the first identifying feature of the next succeeding object and carrying out the steps of choosing a first threshold level voltage, classifying the signals, forming the monochrome image, and comparing the image for the last-mentioned first identifying feature to obtain a matching threshold level voltage An+1 for said last mentioned first identifying feature, calculating a target threshold level voltage Bn+1)T for the second identifying feature on said next succeeding object according to the expression;
space="preserve" listing-type="equation">B.sub.n+1)T =f(A.sub.n+1 *, B.sub.n *, A.sub.n+1)where An+1 * is the average matching threshold level voltage for the first identifying features of the succession of objects including matching threshold level voltage An+1, Bn * is the average matching threshold level voltage for the second identifying features of the succession of objects including matching threshold level voltage Bn ; and obtaining an image of the second identifying feature of the next succeeding object and carrying out the steps of classifying the signals using the newly calculated target threshold level voltage, forming the monochrome image and comparing the image for the last mentioned second identifying feature. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. An apparatus for detecting the presence of an object moving along an assembly line among a succession of objects and which objects have at least two identifying features thereon, comprising:
-
means for obtaining an image of the first identifying feature of one of the objects constituted by a plurality of voltage signals of more than two different voltages; means for choosing a first threshold level voltage for the first identifying feature of said one object; means for classifying the signals of said plurality of voltage signals for said first identifying feature of said one object into signals greater than the first threshold level voltage and signals less than the first threshold level voltage; means for forming from said thus classified signals a monochrome image; means for comparing said monochrome image with a pre-memorized image of the first identifying feature constituted by a plurality of voltage signals for determining whether the monochrome image corresponds to the pre-memorized image, and when said image of said first identifying feature corresponds with the pre-memorized image, designating the threshold level voltage at which the correspondence occurs as matching threshold level voltage An ; means for obtaining an image of the second identifying feature of said one object constituted by a plurality of voltage signals of more than two different voltages; means for calculating a target threshold level voltage Bnt for the second identifying feature of said one object according to the expression;
space="preserve" listing-type="equation">B.sub.nt =f(A.sub.n *, B.sub.n-1 *, A.sub.n)where An * is the average matching threshold level voltage for the first identifying features of preceding objects in the succession and Bn-1 * is the average matching threshold level voltage for the second identifying features of the preceding objects in the succession; means for classifying the signals of said plurality of voltage signals for said second identifying feature into signals greater than the target threshold level voltage and signals less than the target threshold level voltage; means for forming from said thus classified signals a monochrome image of second identifying feature; means for comparing said monochrome image of the second identifying feature with a pre-memorized image of the second identifying feature constituted by a plurality of voltage signals for determining whether the monochrome image of the second identifying feature corresponds to the pre-memorized image of the second identifying feature, and when said image of said second identifying feature corresponds with the pre-memorized image, designating the threshold level voltage at which correspondence occurs as matching threshold level voltage Bn ; means obtaining an image of the first identifying feature of the next succeeding object and for carrying out the steps of choosing a first threshold level voltage, classifying the signals, forming the monochrome image, and comparing the image for the last mentioned first identifying feature to obtain a matching threshold level voltage An+1 for said last mentioned first identifying feature, means for calculating a target threshold level voltage B.sub.(n-1)T for the second identifying feature on said next succeeding object according to the expression;
space="preserve" listing-type="equation">B.sub.n+1)T =f(A.sub.n+1 *, B.sub.n *, A.sub.n+1)where An+1 * is the average matching threshold level voltage for the first identifying features of the succession of objects including matching threshold level voltage An+1, Bn * is the average matching threshold level voltage for the second identifying features of the succession of objects including matching threshold level voltage Bn ; and means for obtaining an image of the second identifying feature of the next succeeding object and carrying out the steps of classifying the signals using the newly calculated target threshold level voltage, forming the monochrome image and comparing the image for the last mentioned second identifying feature.
-
Specification