Colour Vision Tools Enable Cost Effective Inspection of Airbag Sensors During Manual Production

September 2010. Cognex Corporation: A single misplaced wire in an airbag sensor connector has the potential to cause a fatality. A critical part of making sure the connector is assembled correctly requires verifying that the right colour wire is attached to each connector.

This sort of inspection can be automated very effectively using colour machine vision. However, in the past this would have been expensive, due to the difficulty of writing colour inspection algorithms that can distinguish between different shades of the same colour.

Today’s easier, more effective colour vision tools have enabled a connector manufacturer to implement a colour vision inspection that has demonstrated 100% accuracy for this critical inspection. New Cognex colour tools greatly reduced the time required for programming the vision system, making it cost effective enough to use machine vision even during early stages of production when manual inspection would normally be used. The supplier can now take advantage of machine vision to perform this critical safety inspection starting from the very beginning of production and further reduce the risk of errors.

The connector manufacturer asked AVI Inc., a leading machine vision integrator based in North Little Rock, Arkansas, to develop two separate machine vision solutions: the first would be used to inspect the part while it was produced manually. The second would be used on the automated machinery that was being designed to produce the part as production volume ramped up.

Cognex recently introduced several new colour tools that made this particular connector inspection much simpler to program. The MatchColour™ tool is a high speed colour sortation tool that uses 24-bit colour resolution to reliably distinguish between small variations in hue. The ExtractColour™ tool enables users to quickly train highly complex colour models.

“The biggest challenge in this application is the need to distinguish between wires that are different shades of the same colour,” said Rick Farrer of AVI. “In the past we would have had to write a long and complex program to tell them apart. Whenever the customer indicated a new part number with a different colour pattern, the program would have had to be modified.”

Farrer developed the same machine vision inspection application for both the manual and automated production stage using Cognex In-Sight® Explorer software. Two vision systems are used to perform the five inspection operations required on each connector: an In-Sight Micro 1100C ensures that the right colour wires are attached to each sensor connector; a higher resolution In-Sight 1403C is used to inspect the distance between contacts in the female connectors, to detect the presence of four red dots that indicate that the connector has been assembled correctly, to check for a black dot that indicates the connector has passed a previous electrical test, and to verify the colour of the latch and ensure it is in the locked position.

Testing showed that machine vision is 100% effective in detecting problems with the airbag sensors. The vision systems are now being used in production on two manual lines and based on their success AVI received another order to develop vision systems for the automated line.

About Cognex
Cognex Corporation designs, develops, manufactures and markets machine vision sensors and systems, or devices that can "see." Cognex vision sensors and systems are used in factories around the world where they guide, inspect, gauge, identify and assure the quality of a wide range of items during the manufacturing process. Cognex is the world's leader in the machine vision industry, having shipped more than 500,000 machine vision systems, representing over $2.5 billion in cumulative revenue, since the company's founding in 1981. Headquartered in Natick, Massachusetts, USA, Cognex has regional offices and distributors located throughout North America, Japan, Europe, Asia and Latin America. For details, visit Cognex on-line at http://www.cognex.com.