System and method for automatically recovering video tools in a vision system

• US 7,454,053 B2
• Filed: 10/29/2004
• Issued: 11/18/2008
• Est. Priority Date: 10/29/2004
• Status: Active Grant

• Current Assignee: Mitutoyo Corporation
• Original Assignee: Mitutoyo Corporation
• Inventors: Bryll, Robert K., Ariga, Kozo
• Primary Examiner(s): Mariam; Daniel G
• Application Number:
  US10/978,227
• Publication Number:
  US 20060093205A1
• Time in Patent Office: 1,481 Days
• Field of Search: 382141-152, 348/92, 348/95, 348/125, 702/34
• US Class Current: 382/152
• CPC Class Codes: G06T 2207/30164 Workpiece; Machine component
• CPC Class Codes: G06T 7/0004 Industrial image inspection
• CPC Class Codes: G06V 10/26 Segmentation of patterns in the image field; Cutting or merging of image elements to establish the pattern region, e.g. clustering-based techniques; Detection of occlusion
• CPC Class Codes: G06V 10/457 by analysing connectivity, e.g. edge linking, connected component analysis or slices
• CPC Class Codes: G06V 10/945 User interactive design; Environments; Toolboxes
• CPC Class Codes: G06V 2201/06 Recognition of objects for industrial automation

Abstract

Methods and systems for automatically recovering a failed video inspection tool in a precision machine vision inspection system are described. A set of recovery instructions may be associated or merged with a video tool to allow the tool to automatically recover and proceed to provide an inspection result after an initial failure. The recovery instructions include operations that evaluate and modify feature inspection parameters that govern acquiring an image of a workpiece feature and inspecting the feature. The set of instructions may include an initial phase of recovery that adjusts image acquisition parameters. If adjusting image acquisition parameters does not result in proper tool operation, additional feature inspection parameters, such as the tool position, may be adjusted. The order in which the multiple feature inspection parameters and their related characteristics are considered may be predefined so as to most efficiently complete the automatic tool recovery process.

Claims

1. A method for automatically recovering a failed video tool in a precision machine vision inspection system, wherein the video tool fails based on an initial set of feature inspection parameters used for acquiring a workpiece feature image and operating the video tool to inspect the workpiece feature in the image,

the method comprising:

(a) upon detecting the video tool failure, evaluating at least one feature inspection parameter based on an analysis of the workpiece feature image;

(b) for the at least one feature inspection parameter evaluated based on the analysis of the workpiece feature image, determining whether the feature inspection parameter falls within a predefined acceptable range for that feature inspection parameter; and

(c) if in step (b) it is determined that the feature inspection parameter falls outside the predefined acceptable range, automatically adjusting at least one member of the initial set of feature inspection parameters to provide a replacement set of feature inspection parameters that cause the video tool to operate successfully.

2. The method of claim 1, wherein the at least one feature inspection parameter evaluated based on the analysis of the workpiece feature image comprises at least one image characteristic.

3. The method of claim 2, wherein if at least one image characteristic falls outside of its predefined acceptable range, then automatically adjusting at least one member of the initial set of feature inspection parameters comprises adjusting at least one image acquisition parameter to bring each image characteristic within its predefined acceptable range.

4. The method of claim 3, wherein adjusting at least one image acquisition parameter to bring each image characteristic within its predefined acceptable range comprises adjusting at least one lighting parameter to bring a brightness characteristic within its predefined acceptable range.

5. The method of claim 3, wherein adjusting at least one image acquisition parameter to bring each image characteristic within its predefined acceptable range comprises adjusting at least one focus parameter to bring a focus characteristic within its predefined acceptable range.

6. The method of claim 3, wherein adjusting at least one image acquisition parameter to bring each image characteristic within its predefined acceptable range comprises:

first adjusting at least one lighting parameter to bring a brightness characteristic within its predefined acceptable range; and

following the first adjustment, secondly adjusting at least one focus parameter to bring a focus characteristic within its predefined acceptable range.

7. The method of claim 3, wherein, after adjusting at least one image acquisition parameter to bring each image characteristic within its predefined acceptable range, automatically adjusting at least one member of the initial set of feature inspection parameters further comprises:

(i) forming a test set of feature inspection parameters by replacing each counterpart in the initial set of feature inspection parameters with the at least one adjusted image acquisition parameter used to bring each image characteristic within its predefined acceptable range;

(ii) acquiring a workpiece feature image and operating the video tool to inspect the workpiece feature in the image based on the test set of feature inspection parameters; and

(iii) if the video tool operates successfully, using the test set of feature inspection parameters as the replacement set of feature inspection parameters that cause the video tool to operate successfully.

8. The method of claim 7, wherein if the video tool operates successfully during an execution of step (iii), then at least one step is executed from the group of steps comprising:

the step of automatically substituting the replacement set of feature inspection parameters for the initial set of feature inspection parameters during the operation of a part program,

the step of automatically substituting the replacement set of feature inspection parameters for the initial set of feature inspection parameters during a training mode of operation of the precision machine vision inspection system, and

the step of automatically using the inspection results determined during the successful operation of the video tool at step (iii) as inspection results for the current video tool operation in a part program, and automatically continuing with the next operation of the part program.

9. The method of claim 8, wherein, if the video tool is an edge tool and the video tool fails in step (iii), automatically adjusting at least one member of the initial set of feature inspection parameters further comprises:

(iv) determining whether the video tool did not encompass an edge in step (ii);

(v) if the video tool did not encompass an edge in step (ii), determining the location of the edge nearest to the video tool and adjusting tool location parameters included in the test set of feature inspection parameters, such that the video tool will encompasses the nearest edge; and

(vi) repeating steps (ii) and (iii).

10. The method of claim 9, wherein, if the video tool is an edge tool and the video tool fails in step (vi), automatically adjusting at least one member of the initial set of feature inspection parameters further comprises:

(vii) lowering an edge strength threshold parameter of the test set of feature inspection parameters; and

(viii) repeating steps (ii) and (iii).

11. The method of claim 1, wherein an allowed automatic adjustment range for at least one of the set of feature inspection parameters consisting of a lighting parameter, a focus parameter, tool location parameters, and an edge strength parameter, is determined by a user of the precision machine vision inspection system by operating a user interface of the precision machine vision inspection system.

12. A computer readable medium usable in a precision machine vision inspection system, the medium comprising computer instructions to execute a routine for automatically recovering a failed video tool in the precision machine vision inspection system, wherein the video tool fails based on an initial set of feature inspection parameters used for acquiring a workpiece feature image and operating the video tool to inspect the workpiece feature in the image,

the routine comprising:

(a) upon detecting the video tool failure, evaluating at least one feature inspection parameter based on an analysis of the workpiece feature image;

(b) for the at least one feature inspection parameter evaluated based on the analysis of the workpiece feature image, determining whether the feature inspection parameter falls within a predefined acceptable range for that feature inspection parameter; and

(c) if in step (b) it is determined that the feature inspection parameter falls outside the predefined acceptable range, automatically adjusting at least one member of the initial set of feature inspection parameters to provide a replacement set of feature inspection parameters that cause the video tool to operate successfully.

13. The computer readable medium of claim 12, wherein the at least one feature inspection parameter evaluated based on the analysis of the workpiece feature image comprises at least one image characteristic.

14. The computer readable medium of claim 13, wherein if at least one image characteristic falls outside of its predefined acceptable range, then automatically adjusting at least one member of the initial set of feature inspection parameters comprises adjusting at least one image acquisition parameter to bring each image characteristic within its predefined acceptable range.

15. The computer readable medium of claim 14, wherein adjusting at least one image acquisition parameter to bring each image characteristic within its predefined acceptable range comprises adjusting at least one lighting parameter to bring a brightness characteristic within its predefined acceptable range.

16. The computer readable medium of claim 14, wherein adjusting at least one image acquisition parameter to bring each image characteristic within its predefined acceptable range comprises adjusting at least one focus parameter to bring a focus characteristic within its predefined acceptable range.

17. The computer readable medium of claim 14, wherein, after adjusting at least one image acquisition parameter to bring each image characteristic within its predefined acceptable range, automatically adjusting at least one member of the initial set of feature inspection parameters further comprises:

(i) forming a test set of feature inspection parameters by replacing each counterpart in the initial set of feature inspection parameters with the at least one adjusted image acquisition parameter used to bring each image characteristic within its predefined acceptable range;

(ii) acquiring a workpiece feature image and operating the video tool to inspect the workpiece feature in the image based on the test set of feature inspection parameters; and

(iii) if the video tool operates successfully, using the test set of feature inspection parameters as the replacement set of feature inspection parameters that cause the video tool to operate successfully.

18. A precision machine vision inspection system comprising:

(a) a video tool, wherein the initial operation of the video tool when inspecting a workpiece is based on an initial set of feature inspection parameters used for acquiring a workpiece feature image and operating the video tool to inspect the workpiece feature in the image, and a video tool failure may occur during the initial operation;

(b) an automatic tool recovery routine comprising computer executable instructions for performing the steps of;

(i) upon detecting the video tool failure, evaluating at least one feature inspection parameter based on an analysis of the workpiece feature image;

(ii) for the at least one feature inspection parameter evaluated based on the analysis of the workpiece feature image, determining whether the feature inspection parameter falls within a predefined acceptable range for that feature inspection parameter; and

(iii) if in step (ii) it is determined that the feature inspection parameter falls outside the predefined acceptable range, automatically adjusting at least one member of the initial set of feature inspection parameters to provide a replacement set of feature inspection parameters that cause the video tool to operate successfully; and

(c) a user interface for permitting a user to define the automatic tool recovery routine.

19. The precision machine vision inspection system of claim 18, wherein the user interface permits the user to determine an allowed automatic adjustment range for at least one of the set of feature inspection parameters.

20. The precision machine vision inspection system of claim 19, wherein the set of feature inspection parameters comprises a lighting parameter, a focus parameter, tool location parameters, and an edge strength parameter.