One Part at a Time

On conventional assembly lines, parts were mass produced. These large production lots involved extensive setup and configuration for manufacturing and inspection procedures. This isn't always the case today. Within the automotive industry, in particular, production lots as low as one are not uncommon. This new manufacturing standard required substantial changes to assembly and inspection procedures, and offered unique challenges to vision system architects.

 

Enter Avalon Vision Solutions. Four years ago, the company, based in Lithia Springs, (Atlanta) Georgia, began developing a new inspection system to accommodate these changes. Bill Nicol, VP, Sales & Marketing, explains. "Our automotive customers told us they would be sending multiple products down a common assembly line sequentially." This concept, assembling different parts on a common assembly line in the ordering sequence, is one of the primary requirements of an automotive production technique known as In-Line Vehicle Sequencing (ILVS). Implementing this new assembly procedure would complicate the operators' tasks, since the assembly line has to be configured for each part being assembled. In addition, automated inspection technology would be required to minimize errors in the part being assembled.

 

The result is Avalon's QualityStation with PlantVision 7. The QualityStation is a vision system with event-driven I/O architecture that permits one active program to accommodate several different product models. The setup for each product is stored in the QualityStation as an event. When the controller receives an input signal that identifies the event, it executes the inspection criteria for that event. The QualityStation "makes setups and SPC [Statistical Process Control] data acquisition and reporting much less complicated than it would be running different programs for each product model," adds Nicol.

 

 

Plant-floor personnel sets up the inspection procedure through a touch-screen interface for the part that is about to be assembled. When the part is assembled, a trigger signal activates the cameras. A bar code is read by a separate scanner, which informs the system which part is to be inspected. Using the images captured by the cameras, the part is then inspected according to the procedures that were specified by the plant-floor technician. This will include locating, counting and measuring.

 

PlantVision 7 is the software component in the system. The procedures laid out in the touch-screen interface, called SmartWindows, use processing modules from the Matrox Imaging Library (MIL). The SmartWindows provide a user-friendly interface for complicated inspection tasks. For example, the pattern search tool uses pattern matching functions to identify specific features. The Locator tool uses blob analysis and histogram functions to determine the centroid of the object being inspected, so that it can be measured. Matrox Meteor-II frame grabbers are connected to as many as twenty-four cameras to capture the images required for inspection. All the results from the inspection procedures, including image data, are logged into the ProcessRx SPC database, which is accessible through the web.