Machine vision method and apparatus

• US 4,678,920 A
• Filed: 06/17/1985
• Issued: 07/07/1987
• Est. Priority Date: 06/17/1985
• Status: Expired due to Fees

• Current Assignee: General Motors Auto OOO (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Tkaczyk, Richard J., Iadipaolo, Rene M.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Cooper, Crystal D.
• Application Number:
  US06/745,079
• Time in Patent Office: 750 Days
• Field of Search: 356/376, 356/386, 356/387, 358/101, 358/107, 250/560, 250/561
• US Class Current: 250/559.05
• CPC Class Codes: B07C 5/10 measured by light-responsive means sorting according to colour B07C5/342
• CPC Class Codes: G01B 11/024 by means of diode-array scanning

Abstract

A first linear sensor tracks the movement of an object through an inspection station and a second linear sensor views the object transverse to the object path to acquire a line image of the object, and a synchronizing arrangement responds to the sensed position of the object to trigger the second sensor at spaced object positions to obtain a plurality of line images which cummulatively represent the object image. The image is compared, line-by-line, as acquired with a stored model of the object to determine the correlation between the object and the model.

Claims

1. Machine vision apparatus for acquiring the image of a moving object comprising;

means for moving the object along a predetermined path,

a first linear sensor arranged to track the progress of the object along the path and for generating signals representing object position,

a second linear sensor arranged to sense portions of the object in a plane transverse of the path for generating streams of data representing line images in the plane, and

synchronizing means coupled to the sensors and responsive to the signals for outputting streams of data from the second sensor at predetermined object positions whereby as the object advances through the plane the second sensor obtains many line images which cumulatively represent an image of the object.

2. Machine vision apparatus as described in claim 1 wherein the first linear sensor is a first array of photodetector elements arranged to view the object along a line parallel to the path so that the elements sequentially detect a salient feature of the object, and the second linear sensor is a second array of photodetector elements arranged to sequentially view a plurality of slices of the object generally perpendicular to the path.

3. Machine vision apparatus as described in claim 2 where the synchronizing means comprises;

a counter for emitting a counter signal identifying each element of the first sensor which detects the salient feature of the object,

memory means storing codes corresponding to the counter signals for selected elements to trigger the output from the second sensor, and

comparator means responsive to the counter signal and the stored codes for emitting a synch pulse to output the streams of data from the second sensor, whenever the counter signal matches one of the codes.

4. Machine vision apparatus for acquiring the image of a moving object and detecting the object profile comprising;

means for moving the object along a predetermined path,

a first linear sensor arranged to track the progress of the object along the path and for generating signals representing object position,

a second linear sensor arranged to sense object information in a plane transverse of the path,

synchronizing means coupled to the sensors and responsive to the signals for outputting information from the second sensor at predetermined object positions whereby the second sensor obtains many sets of object information as the object advances through the plane, and

means for processing the sets of information to determine the profile of the object.

5. Machine vision apparatus for acquiring the image of a moving object and comparing the image to a model comprising;

means for moving the object along a predetermined path,

a first linear sensor arranged to track the progress of the object along the path and for generating signals representing object position,

a second linear sensor arranged to sense object information in a plane transverse of the path,

synchronizing means coupled to the sensors and responsive to the signals for outputting information from the second sensor at predetermined object positions whereby the second sensor obtains many sets of object information representing the image as the object advances through the plane,

means for storing data representing a model, and

means for processing the sets of information to compare the image to the model.

6. A machine vision method of acquiring the image of an object comprising the steps of;

moving the object through a predetermined path,

sensing the position of the object at an array of points along the path to produce position signals, and

in response to the position signals sequentially sensing line images of the object in a plane transverse to the path to obtain a plurality of line images which cumulatively represent the object image.

7. A method as c-aimed in claim 6 wherein the said array of points is arranged parallel to the path so that the points sequentially sense the same portion of the object, and wherein the said transverse plane is substantially perpendicular to the path.

8. A machine vision method of acquiring the image of an object comprising the steps of;

moving the object in a predetermined path through an inspection station,

back lighting the object at the inspection station,

sequentially sensing an edge of the silhouette of the object at a line of points to produce position signals as the object moves through the inspection station, and in response to the position signals, sensing at spaced object positions line images of the object shadow to obtain a plurality of line images which cumulatively represent the image of the object shadow.