Sparkplug Inspection

Application Type	Inspection
Image Characteristics	Monochrome; Good Contrast; Very Little Image Noise
Machine Vision Tool(s)	Edge Detection; Caliper

The sparkplug inspection determines the width of the spark plug base and the gap between the electrodes using the Edge Detection and Caliper functions.

Edge Detection: All Edges (Simple Edge Detection)—Finds points on either end of the base of the spark plug. The edge detection process looks for edges (sharp transitions in pixel values) along a search path. The search path is defined as the line that is drawn across the base. The line is drawn long enough so that it always cuts through the base even if the spark plug moves from image to image.

The simple edge tool is used to detect the edges because the spark plug is well contrasted from the image and there is no noise in the image. Based on the line profile obtained along the search line, a threshold value of 128 is used to detect the edges.

Edge Detection: All Edges (Simple Edge Detection)—Finds points on the spark plug electrodes on either side of the gap. In this case, the search line is drawn so it cuts across the spark plug electrodes on either side of the gap.

Caliper—Measures the distance between the points found on the base to measure the width of the base. The distance between the points found on either side of the gap indicates the length of the gap.