What sensors are used to detect the hot LED lights on the FRC field?

[Lightfoot26]

Originally Posted by Alan Anderson

You only need to check for the presence or absence of reflections from the horizontal target. A Class 1 laser sensor can be pointed at the dynamic vision target before the match begins, and it'll tell you whether or not the target is still there a moment after autonomous mode starts.

You hit the nail on the head Alan!

The sensor I posted actually has a built in sensing light that illuminates when "the circuit is complete" for lack of a better term. This is all internal to the sensor. If the target is present both a green and amber light located on the top of the sensor will illuminate, if there is power to the sensor, but the target is not present, only the green light illuminates. That's the elegance behind a sensor of this design. Very easy to recognize the presence of the target without any additional coding or alignment mechanism. We weren't sure if this was the route we could take pre-Team Update 1... but after we learned that pre match setup will have both targets revealed, we went for it!

Like I said before, camera stuff consumes a lot of resources (at least on our team) e.g. coding time, debug time, and bandwidth among others, and we only use vision if we rule out all other possibilities. 5 extra points didn't seem worth consuming those resources to us, but in 1625 nature... we still wanted those points! haha So we opted for the laser. Team 2451 (formerly 2949) did a similar laser setup in 2012, from which we drew inspiration.


EDIT: In regards to

Originally Posted by NotInControl

how do you know you are pointing ONLY at the horizontal target when placing on the field?

I guess it is a mixture of what I said above as well as both the retro-reflective properties of the tape and "trial and error" really... The retro reflectability of the tape will help us ensure there is no "spillage" of light from the vertical segment of tape, and "trial and error" helps improve our drive teams ability to position the sensor accurately. This "trial and error" methodology seems cumbersome yes, but most dead reckoned auton systems have some degree of this process.

[NotInControl]

Originally Posted by Lightfoot26

You hit the nail on the head Alan!

The sensor I posted actually has a built in sensing light that illuminates when "the circuit is complete" for lack of a better term. This is all internal to the sensor. If the target is present both a green and amber light located on the top of the sensor will illuminate, if there is power to the sensor, but the target is not present, only the green light illuminates.

I agree with the "not use vision if you don't have too." In 2012, we were a team that had no vision on our robot. Our drivers used a line marker at the tail of robot to line up with the center of the key to make key shots. IT was actually a point of pride after a while to have the performance we did without vision. We ranked 1st seed in both regionals we attended that year, so it worked out well for us.

This year, we have vision running on a beaglebone using opencv and ffmpeg. It was a system we received from our friends 118, and have been modifying for our specific use.

I was curious about placement of the robot, because your initial post metioned it was an IR sensor. I didn't see wavelength specified on the link you provided, but I do honestly hope this system works out for you.

It will be pretty cool to see such a simple system reliably work in auton. My fear would be the initial lineup, and shooting prematurely because I was looking at the horizontal target instead of the vertical, but it sounds like you have a plan to overcome that.

Goodluck.

Reagrds,
Kevin

[Lightfoot26]

Sounds like a pretty neat setup! I hope it works out for you! I am anxious to see how well our system performs. It's hard to tell at the moment because I am at college 300mi away from my former team ( The one I now mentor (sorta) lol )! We shall see!

I'll provide followup and/or perpetuate this conversation when I know more! Good Luck!!