MACHINE VISION SYSTEMS AND METHODS WITH PREDICTIVE MOTION CONTROL

• US 20160065912A1
• Filed: 11/06/2015
• Published: 03/03/2016
• Est. Priority Date: 05/22/2012
• Status: Active Grant

• Current Assignee: Cognex Corporation
• Original Assignee: Cognex Corporation
• Inventors: Peterson, Dale
• Granted Patent: US 10,083,496 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B07C 5/02 Measures preceding sorting, e.g. arranging articles in a stream orientating sorting and transport of caps B67B3/06
• CPC Class Codes: B07C 5/342 according to optical properties, e.g. colour according to radiation transmittivity B07C5/3416
• CPC Class Codes: G01B 11/04 specially adapted for measuring length or width of objects while moving
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G01N 2021/845 Objects on a conveyor
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: G03B 15/16 for photographing the track of moving objects high-speed photography G03B39/00
• CPC Class Codes: G06T 2207/30108 Industrial image inspection
• CPC Class Codes: G06T 3/40 Scaling of whole images or parts thereof, e.g. expanding or contracting
• CPC Class Codes: G06T 7/001 using an image reference approach
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80
• CPC Class Codes: H04N 23/661 Transmitting camera control signals through networks, e.g. control via the Internet
• CPC Class Codes: H04N 23/73 by influencing the exposure time

Abstract

Systems and methods trigger an image acquisition of an object using motion data communicated from a motion controller on a network, the motion controller coupled to a motion drive. Based upon motion data from the motion controller, a virtual axis application is used to plan the movement of a virtual axis for a motion cycle, the virtual axis allowing an acquisition trigger rate to be calculated to follow movement of the object caused by the motion drive. Based on the calculated acquisition trigger rate, an acquisition trigger signal is generated for triggering the image acquisition of the object.

Claims

1. A vision system for triggering image acquisition of one or more objects using motion data communicated from a motion controller on a network, the motion controller coupled to a motion drive, the system comprising:

an image acquisition device;

an acquisition controller coupled to the image acquisition device, the acquisition controller including a network interface, the network interface operable to couple to the network;

wherein the acquisition controller, upon receiving motion data from the motion controller, uses a virtual axis application to plan movement of a virtual axis for a motion cycle, the virtual axis allowing an acquisition trigger rate to be calculated by the acquisition controller that follows movement of the one or more objects caused by the motion drive; and

wherein, based on the calculated acquisition trigger rate, the acquisition controller generates an acquisition trigger signal for triggering the image acquisition of the one or more objects.

2. The vision system according to claim 1, further comprising:

a comparison module configured to;

compare a model of the one or more objects to image data from the image acquisition of the one or more objects; and

identify a deviation of the image data from the model;

wherein, based upon the deviation of the image data from the model and the movement of the virtual axis, the acquisition controller calculates an updated acquisition trigger rate; and

wherein, based on the updated acquisition trigger rate, the acquisition controller generates an updated acquisition trigger signal for triggering subsequent image acquisition of the one or more objects.

3. The vision system according to claim 2, wherein the model of the one or more objects includes one or more virtual objects.

4. The vision system according to claim 2, wherein identifying the deviation of the image data from the model includes identifying one or more of a deviation of an aspect ratio represented in the image data from a model aspect ratio, and a deviation of a linear dimension represented in the image data from a model linear dimension.

5. The vision system according to claim 4, wherein the updated acquisition trigger rate corrects for the deviation in the aspect ratio represented in the image data.

6. The vision system according to claim 2, wherein identifying the deviation of the image data from the model includes identifying, for a movement of the one or more objects that is caused by the motion drive, an effect of one or more of jitter and slack on the movement.

7. The vision system according to claim 2, further comprising:

a reporting module configured to generate a user report based upon the deviation of the image data from the model, and to transmit the user report for review by a user.

8. The vision system according to claim 1, further comprising:

a comparison module configured to;

compare a model of the one or more objects to image data from the image acquisition of the one or more objects; and

identify a deviation of the image data from the model; and

a post-processing module configured to modify the image data, for further processing by one or more machine vision tools, based upon the deviation of the image data from the model.

9. The vision system according to claim 8, wherein the modifying of the image data by the post-processing module includes modifying pixel data in order to rescale an aspect ratio represented in the image data.

10. The vision system according to claim 1, further comprising:

a comparison module configured to;

compare a model of the one or more objects to image data from the image acquisition of the one or more objects; and

identify a deviation of the image data from the model; and

a tool adjustment module configured to adjust one or more parameters of one or more machine vision tools, based upon the deviation of the image data from the model.

11. The vision system according to claim 10,

wherein identifying the deviation of the image data from the model includes identifying a deviation of an aspect ratio represented in the image data from a model aspect ratio;

and

wherein adjusting the one or more parameters of the one or more machine vision tools includes adjusting the one or more parameters based upon the deviation of the aspect ratio represented in the image data.

12. A vision system comprising:

an image acquisition device operable to trigger image acquisition of one or more objects using motion data communicated from a motion controller on a network, the motion controller coupled to a motion drive;

the image acquisition device being in communication with a virtual axis application and an acquisition controller, the acquisition controller being coupleable to the network;

a common time reference provided by at least one of the motion controller, an image acquisition device clock, a dedicated master clock, and the motion drive;

wherein the image acquisition device, upon receiving the motion data communicated from the motion controller, uses the virtual axis application to plan movement of a virtual axis for a motion cycle, the virtual axis operable to follow relative movement of the one or more objects caused by the motion drive; and

wherein, based on movement of the virtual axis, the image acquisition device generates an acquisition trigger signal for triggering the image acquisition of the one or more objects.

13. The vision system according to claim 12, wherein the image acquisition device compares a model of the one or more objects to image data from the image acquisition of the one or more objects in order to identify a deviation of the image data from the model;

wherein, based upon the deviation of the image data from the model and the movement of the virtual axis, the image acquisition device generates an updated acquisition trigger signal; and

wherein, based on the updated acquisition trigger rate, the image acquisition device generates an updated acquisition trigger signal for triggering subsequent image acquisition of the one or more objects.

14. The vision system according to claim 13, wherein the acquisition trigger signal triggers the image acquisition at first angular intervals of the movement of the virtual axis;

and

wherein the updated acquisition trigger signal triggers the subsequent image acquisition at second angular intervals of the movement of the virtual axis, the second angular intervals being at least partly different from the first angular intervals.

15. The vision system according to claim 12, wherein the image acquisition device compares a model of the one or more objects to image data from the image acquisition of the one or more objects in order to identify a deviation of the image data from the model;

and

wherein the image acquisition device modifies the image data, based upon the deviation of the image data from the model, for further processing by one or more machine vision tools.

16. The vision system according to claim 12, wherein the image acquisition device compares a model of the one or more objects to image data from the image acquisition of the one or more objects in order to identify a deviation of the image data from the model;

and

wherein the image acquisition device adjusts one or more parameters of one or more machine vision tools, based upon the deviation of the image data from the model, for further processing of the image data by one or more machine vision tools.

17. A method for acquiring one or more images of one or more objects, the method comprising:

providing a common time reference to an image acquisition device and a motion controller, the image acquisition device and the motion controller being in communication on a network;

the motion controller sending motion data to a motion drive;

the motion controller sending the motion data over the network to the image acquisition device;

upon receiving the motion data, the image acquisition device planning movement of a virtual axis, such that the virtual axis moves in a fixed relationship to the motion drive;

using the virtual axis, generating an image acquisition trigger rate that virtually follows movement of the one or more objects;

using the image acquisition trigger rate, generating an image acquisition trigger signal; and

using the image acquisition device and the image acquisition trigger signal, acquiring the one or more images of the one or more objects.

18. The method according to claim 17, further comprising:

comparing a model of the one or more objects to the one or more images;

identifying a deviation of the one or more images from the model;

using the deviation of the one or more images from the model and the movement of the virtual axis, generating an updated acquisition trigger rate that virtually follows the movement of the one or more objects; and

using the image acquisition device and the updated acquisition trigger signal, acquiring additional one or more images of the one or more objects.

19. The method according to claim 17, further comprising:

comparing a model of the one or more objects to the one or more images;

identifying a deviation of the one or more images from the model; and

using the deviation of the one or more images from the model, modifying the one or more images for further processing by one or more machine vision tools.

20. The method according to claim 17, further comprising:

comparing a model of the one or more objects to the one or more images;

identifying a deviation of the one or more images from the model; and

using the deviation of the one or more images from the model, adjusting one or more parameters of one or more machine vision tools for processing the one or more images.