Five edge inspection techniques in machine vision technology
John Stamos, 09-13-2011
Establishing reliable edge inspection parameters and thresholds in your machine vision system is critical to getting consistent quality control from your production line.
There are several measurement tools available for completing this task successfully. Here’s a quick look at five of these tools:
- Distance measurement – measures the distance between features, not just edges
- Angle measurement – determines the angle between two edges
- Circle diameter measurement - calculates that distance between opposite ends of a circle
- Circle concentricity – measures the distance from the center of one circle to another. A good example of this is a washer’s inner and outer circle centers’ distance = 0
- Radius measurement – creates an arc finder and returns the radius measurement
Cognex machine vision systems also feature an InspectEdge tool that works on straight and circular parts and also helps find gaps as well as defects.
When using edge inspection techniques for defect detection in objects, use a min/max tool to get the closest and furthest point from the best fit line to ensure more consistent pass/fail determinations.