Method for setting parameters of a vision detector using production line information

• US 8,295,552 B2
• Filed: 04/29/2009
• Issued: 10/23/2012
• Est. Priority Date: 06/09/2004
• Status: Active Grant

• Current Assignee: Cognex Technology & Investment Corporation (Cognex Corporation)
• Original Assignee: Cognex Technology & Investment Corporation (Cognex Corporation)
• Inventors: Mirtich, Brian V., Silver, William M.
• Primary Examiner(s): Tabatabai, Abolfazl
• Application Number:
  US12/432,235
• Publication Number:
  US 20090273668A1
• Time in Patent Office: 1,273 Days
• Field of Search: 382/103, 382/104, 382/107, 382/141, 382/143, 382/162, 348/86, 348/94, 348/154, 348/155, 348/207.11, 348/208.16, 348/211.99, 348/333.02, 348/352
• US Class Current: 382/107
• CPC Class Codes: G03B 7/087 for control of both exposure time and aperture
• CPC Class Codes: G03B 7/097 for control of both exposure time and aperture
• CPC Class Codes: H04N 23/62 Control of parameters via user interfaces

Abstract

Disclosed are systems and methods for setting various operating parameters of a vision detector from production line information that can be supplied by a manufacturing technician who is not skilled in the art of the invention. These operating parameters include shutter time, video gain, idle time, frame count, and locator search range. The production line information includes line speed, field of view size, direction of motion, and object spacing.

Claims

1. A method for setting an idle time parameter of a vision detector comprising

configuring the vision detector to detect a sequence of discrete objects in continuous motion at a nominal object speed relative to a field of view of the vision detector, including detecting each object of the sequence of discrete objects responsive to an analysis of at least one frame captured by the vision detector, each frame comprising an image of the field of view;

choosing a motion parameter that specifies a desired motion of an object, in units related to pixels, during an idle step of the vision detector, the idle step comprising an interval of time during which objects are not detected;

estimating, responsive to the nominal object speed, an apparent object speed in units related to pixels per unit of time;

computing, responsive to the apparent object speed and the motion parameter, a desired idle time; and

setting the idle time parameter of the vision detector to the desired idle time.

2. The method of claim 1, wherein the step of choosing the motion parameter includes choosing the motion parameter so as to avoid detecting an object more than once, and so as to avoid missing an object.

3. The method of claim 1, wherein the idle time parameter comprises a minimum idle time parameter.

4. The method of claim 1, wherein the idle time parameter comprises a maximum idle time parameter.

5. The method of claim 1, wherein the step of computing the desired idle time comprises computing a ratio of the motion parameter to the apparent line speed.

6. A method for setting an idle time parameter of a vision detector comprising:

configuring the vision detector to detect a sequence of discrete objects in continuous motion relative to a field of view of the vision detector, the sequence of discrete objects having a nominal object period between successive objects, wherein configuring the vision detector includes detecting each object of the sequence of discrete objects responsive to an analysis of at least one frame captured by the vision detector, each frame comprising an image of the field of view;

choosing a motion parameter that specifies a desired motion of an object in the sequence of discrete objects, as a fraction of the nominal object period, during an idle step of the vision detector, the idle step comprising an interval of time during which objects are not detected;

computing, responsive to the nominal object period and the motion parameter, a desired idle time; and

setting the idle time parameter of the vision detector to the desired idle time.

7. The method of claim 6, wherein the step of choosing the motion parameter includes choosing the motion parameter so as to avoid detecting an object more than once, and so as to avoid missing an object.

8. The method of claim 6, wherein the idle time parameter comprises a minimum idle time parameter.

9. The method of claim 6, wherein the idle time parameter comprises a maximum idle time parameter.