Using a Light Sensor to Detect Field Gaffers Tape

[pietroglyph]

I'm interested in detecting the gaffers tape field markings for autonomous guidance using a light sensor. If you have any experience with this type of sensor, especially for this specific application, then I'd love to hear about it. To give you more to work off of, I'm interested in these questions specifically:

• Are light sensors difficult to implement?
• Are they reliable for detecting the gaffers tape on the field?
• Do you have any recommendations for specific sensors?

I've seen this used in FLL, and I think that a light sensor was included in the 2004 kit of parts for this purpose, but I haven't been able to find anything much more relevant or specific.

[Jared Russell]

Last year we used a digital Banner sensor with a trim adjustment wheel to detect the gaffer's tape for our non-low bar 2-ball auto mode. Initially we tried to detect the green auto line tape (worked great in our lab with what we thought was the same tape), but at the Championship event we changed it to sense the white mid-line tape instead. The latter worked really well. Don't try to detect green on green

Some tips for doing this:
1) Many optical or IR sensors do the job, but nice features to have are a trim wheel and an LED to tell you when you do/don't see the tape. Better sensors also tell you when you are close to the threshold (e.g. you see the tape, but barely - keep tuning for robustness).

2) The sensors we used worked best a few inches above the carpet. Each sensor is different, but most of them will have a range of heights where they work well.

[MrRoboSteve]

We have found that lighting the area being read improves the reliability of the sensor.

[pietroglyph]

Originally Posted by Jared Russell

Last year we used a digital Banner sensor with a trim adjustment wheel to detect the gaffer's tape for our non-low bar 2-ball auto mode. Initially we tried to detect the green auto line tape (worked great in our lab with what we thought was the same tape), but at the Championship event we changed it to sense the white mid-line tape instead. The latter worked really well. Don't try to detect green on green

Some tips for doing this:
1) Many optical or IR sensors do the job, but nice features to have are a trim wheel and an LED to tell you when you do/don't see the tape. Better sensors also tell you when you are close to the threshold (e.g. you see the tape, but barely - keep tuning for robustness).

2) The sensors we used worked best a few inches above the carpet. Each sensor is different, but most of them will have a range of heights where they work well.

Do you have specific part numbers for the sensors you used/a link to a website with info on them?