Gripper Clearance Tool Gripper Clearance Tool Description The Gripper Clearance tool is a filter used to determine which parts can be picked without interference. Instances returned as results have passed the filter. The tool uses histograms (typically one histogram per gripper finger) to determine whether the gripper can pick up a part without interference from another part or edges of the region of interest (ROI). Each set of histograms is applied to each instance in the region of interest. You use the Inspection Configuration field to specify the maximum and minimum Grey Level Mean, Variance, or Histogram pixel count, which are applied to all histograms in the tool.
All histograms for an instance must have a value between the maximum and minimum, inclus- ive, for that instance to pass the filter. l Grey Level Mean - This is absolute greylevel, and will change with lighting and other environmental changes. For this reason, it is best-suited for situations where these conditions will be constant (a clean, homogenous background and constant lighting intensity). l Variance - This is the difference, from the mean, of the greylevel values in the his- togram. Because it is relative, it is useful when lighting and other conditions may change.
l Histogram pixel count - This specifies the number of pixels, in each histogram, that To create a Gripper Clearance tool, right-click in the Tree structure, then select: may fall in the greylevel range that you specify. New > Vision > Tool > Gripper Clearance All histograms are rectangles. Each histogram can be sized, rotated, and moved as needed, to mimic the size and position of the gripper fingers. Editing can be done by modifying Offset and Search Region in the configuration section, or with the mouse in the display window. ACEUser's Guide, 3.6.x, 18316-000 Rev A Page 481