The First Step: Part Location

Part location tools are used to find parts within the vision camera’s field of view and are generally included as part of a larger toolset with a vision system. Part location is typically the first step in any vision application from the simplest presence/absence inspection to robotic pick-and-place operation to assembly verification tasks. Having a powerful part location tool is helpful in reducing costs for costly mechanical fixtures.

Locating parts on a production line presents many challenges. Variations in environmental conditions can alter the way a part appears to a camera. Part location tool performance needs to account for:

• Tolerance to changes in angle: The tool must be able to locate parts at 0 – 360 degrees orientation without sacrificing accuracy. This capability allows parts to be handled move freely down the line.
• Tolerance to changes in optical scale: Even slight camera-to-subject distance fluctuations can change the apparent size of an image, and the vision product should be able to accommodate these variations.
• Tolerance to non-linear lighting changes: The tool must be able to locate parts reliably despite the effects of shadows or stray lighting.
• Tolerance to part overlapping/touching: The tool should be able to locate parts even when a portion of a part appears to be missing due to part overlapping, or in applications where the layered components of a part obscure one another.

A reliable part location tool in your vision system will diminish the need for mechanical fixturing and simplify lighting requirements on the production line. Having a consistent and repeatable part location tool will make your vision applications easier and make them less expensive to implement.