Rockwell Automation 5370-CVIM2 Module - Manual (Page 216)

5 Chapter Chapter 6
Reference Tools
6–57
Here are the criteria for positioning the inner and outer rings of the source
window:
•
The source window should be centered on the circular object. The center
location can be obtained from the “nominal” X– and Y–axis coordinates
reported by the reference line tool.
•
The region between the inner and outer rings must contain a distinct
“index” feature such as a hole, tab, or rivet.
•
For the best rotational accuracy, the feature should be consistent from
object to object, and should be located as far as possible from the center
of the circular object.
When the source window has been resized and repositioned appropriately, as
illustrated by the example in Figure 6.47 (page 6–56), and the source
window’s pick and place function has been exited, the image area between
the two rings of the source window appears in the destination window,
unwrapped.
Here are the criteria for positioning the destination window:
•
The destination window must be tall enough to provide the optimal
angular resolution.
A shorter destination window will make the tool run faster, but it will
provide less angular resolution.
•
The destination window should be as narrow as possible, provided that
the “index” feature remains a distinct pattern within the unwrapped
image. If the possibility of confusion exists between the chosen index
feature and another region of the unwrapped image, then widening the
destination will give better reliability but slower speed.
Figure 6.48 (page 6–58) illustrates how the unwrapped image of the circular
object (see Figure 6.47) appears in the destination window after the
destination window has been appropriately resized and repositioned. Note the
relative position of the “index mark” in the two windows.
At this point, morphology filtering could be used (by picking the
button) to enhance the index feature in the destination window, if desired.
The rotation finder tool is sensitive to variations in lighting and part color
from one inspection to the next; however, this sensitivity can be reduced by
applying a “MAX – MIN” operation, followed by a “MAX” operation.
The next task is the selection of the “feature image” in the destination
window. For this purpose, the
Image Manager panel is accessed by picking
the Image Name field in the tool edit panel. (For general details about the
Image Manager panel, refer to the Image Manager Panel section on page
4–40 of Chapter 4, Inspection Configuration. For additional details, refer to
the Feature Image Configuration section on page 6–30 of this chapter.)