Automotive airbags must deploy within milliseconds to protect lives in the event of an accident. The bags themselves are inflated by highly compressed gas, commonly nitrous oxide contained in a metallic charger. Any defects in the cap or its valve could cause a partial or complete loss of gas before the airbag is triggered, resulting in insufficient pressure for the airbag to inflate properly.
MOSA Industrial Corp. (Yunlin, Taiwan) implemented a vision-based inspection system to check the quality of its inflators' caps, inspecting each cylinder for cracks, valves that are positioned upside down, bends, rust, and concave instead of convex surfaces.
Two parallel conveyor lines feed gas chargers though the vision system after the filling process and prior to shipping. A conveyor belt first delivers the cylinders into a cogwheel that positions them in front of a camera. Because the inflators are randomly fed in, two Guppy F-033B monochrome cameras fromAllied Vision Technologies (Stadtroda, Germany) face each other to capture the head, regardless of orientation. When the inflator passes in front of the cameras, sensors measure where the head is located in order to trigger the appropriate camera to capture the image.
Images are then transmitted via FireWire bus to a processor, where they are analyzed byEuresys's (Angleur, Belgium) Open eVision image-processing software. Failed products are automatically ejected from the line. The system inspects parts at the rate of 13 per second but could manage faster speeds if needed.
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