Quick Answer:
Short Answer
Loss of Contrast Logic holds the guide position during gaps, then resumes tracking when the feature returns.
The Roll-2-Roll® Controller includes Loss of Contrast Logic specifically for this situation. When the sensor encounters a gap where the tracked feature disappears (such as the space between labels), the web guide holds its current position. When the sensor sees the same feature again—matching the width and hue characteristics taught during setup—tracking resumes automatically. This prevents the "hunting" or crashing behavior common with traditional line sensors.