Limelight usage during matches

Hi my name is Tharun and I am a officer of team 8816. This is our second year using limelight and I was wondering what are the rules of using limelight during the teloperated period. I read in the game manual that we can use PID and Limelight to increase the accuracy of some functions and I was wondering what exactly they mean by this.

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You can use your limelight in teleop
As long as the sensors used are legal to have on your robot (not radioactive, no wireless communication, etc.) you are free to automate as much or as little of teleop as you want. If you could make the robot drive autonomously the whole match there would be nothing in the rules against it.


As an example, if you can get the angle of your robot from 2 PIDs, you can calculate (triangulate) the exact position of your robot on the field. That would give you range and angle of travel to any other place on the field.

Do note that the retroreflective tape will not be part of the game starting next year, so you’ll probably want to look into apriltags for using limelight in teleop.


Oh did they confirm that? must’ve missed it

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AprilTags are necessary for triangulation. Otherwise you won’t know which to sources you’ve selected.

IIRC (but I might be wrong), you don’t even need two sources. The Limelight can tell where you are relative to an AprilTag, and the AprilTags are in known positions on the field.

A single AprilTag with a known location on the field is enough to locate yourself. You can get skew, distance, rotation from 1 tag. This is because the tags are printed at a set size as well. Based on the size of the area and the I’d we know which tag it is, where it should be therefore how far away we are from a given point on the field (where the tag is). You could get this with a regular vision target.

The distance up and down, left and right in the image also tell you some distance and strafe information.

Where the AprilTags excel is again the skew, rotation, etc. If you printed a tag and drew a fake floating axis of the origin of the tag it’ll move as you flip the tag around. You can use this additional information to adjust your orientation or even height of an elevator/arm to be “level” with a tag.

Oh okay that clears it up. Thank you!

Oh I think ive seen this in the rapid react comp because some people had shooters that would angle themselves so basically using the limelight you could find the distance from the bot to the hub and then adjust the angle based on that.

Very intresting so actually quick question on this does this basically invalidate the use of basic piplines such as color and more? From what I can gather the only two pipelines I thoguht my team would need would have been a color and retroreflective peipline but the color one isn’t effective and due to this theres no longer a need for the retroreflective pipeline.

I think you could also do some trig as well to find the distance from the corners as well. Also another question I had on a simliar topic was the limelight blindspot(Sorry if this is kind-off random I don’t want to keep making posts) but basically if we want to find any target on the field would you just have to spin around and find it? Idk how else you would do it.

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The color pipeline is occasionally useful for game piece tracking, but the reflective pipeline and green LEDs will soon become unnecessary.

What manual says that?