Potential Limelight Safety Issue 2023

A reddit post pointed out this issue and I think it deserves a discussion.

The placement of the vision markers on the poles is problematic. The limelight cameras are very very bright. They are bright in order to shine at long range on all the targets. The targets are located directly in front of the alliance stations. While this issue will be caused by an Alliance’s own robots, they will unintentionally get blinded by the limelight pointed directly at them.

Possible Solutions: Tinted Safety Glasses, FRC puts a tint on the Alliance Station glass, the vision cameras cannot exceed a certain brightness level, or something else I haven’t thought of?

While the idea of purposely shining your Limelight at a team in order to disrupt their driving ability is a Foul and possibly more, this is going to be a self inflicted issue. Teams need to be aware of this and drive teams should have special PPE to mitigate the Safety Issue and so they can retain full control of the robot during the match.

See my attached diagram. It’s very scientific


This a million percent. You need lights for reflective tape, teams are going to absolutely blind themselves this year.


And the new tape isn’t the old 3M Retroflection Tape. I haven’t gotten to try the new tape out, but it could be dimmer, or bounce oddly and it’s gonna be a change definitely. How did this issue not come up during play testing at HQ?

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I mean, pit vipers technically are safety rated…

(Yes I know, the safety manual says reflective glasses are prohibited, but I wonder if a reason such as “I would like to keep my eyesight past this match” qualifies as an “Accommodation for participants who require tinted safety glasses”)


Are the glasses gonna give a false reflection back to a robot as a vision target? If so a bot might shoot a cone or cube at a driver’s face while they’re focusing elsewhere. They might pass out from the shock when it hits the glass one foot away from their face and bounces back to the field.

It’d certainly scare me


@Connor_H and I are already rocking the vipers. This season won’t know what hit it.


@CarlosGJ If I recall you have something that can help these folks “test” their glasses right? :wink:

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Sure, I can test pretty much anything you want for how well it withstands intense light.

A couple months ago I accidentally tested one of my ceiling tiles at work. They burn through quicker than you’d expect.


Actually, there is something that might help.

Limelight at the TOP of your robot, pointing slightly downwards at the reflectives.

Your eyes will thank you.


It’s our alliance mates and the top level scorers I’m concerned about. We can train our drivers, cant control the training and design done by other teams


I recall similar concerns about Limelights (or other sources of bright light) being used in 2020, where the teams were aiming at the opposing alliance, which was surely not ideal. (Search topics on CD such ad Limelight being illegal etc.)
As pointed above, you could tilt your camera down, which could help a ton, or there is a light filter of sorts in this thread that helps at least a bit. I believe that this could be added at the venue on any robot.
And if you are using a light source that you can turn on/off, please try to have it on for only as long as is needed, so that you don’t blind the refs and human players.


As a reminder, LL 2+ (and later) have a slider to control LED brightness. When targeting the tape for scoring, the robots should already be pretty close, so a relatively dim setting should be fine for this game. (It’s not like last year where you need to see the ring of the HUB, 10 feet overhead and 20 feet away.)


We were just discussing this on our team.
Time for this? Playing With Fusion - SnakeEyes (Far Red) Infrared Raspberry Pi HAT for FRC Robotic Vision

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IR can be just as bad for the eyes, and it’s invisible. Don’t even get me started on UV LEDs…


But at least you’re not squinting to see past it? I think that’s the main issue trying to be solved by this.

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The squinting is your eyes trying to protect themselves from being damaged by too much light energy. Your eyes can’t see IR or UV wavelengths, so they don’t protect themselves, and let it all in.

I don’t know that SnakeEyes is any more/less safe than getting blasted by visible wavelengths, but it isn’t “safer” just because you aren’t squinting.


Me, having many many hours of limelight experience, will tell you that I don’t think the problem will be as bad as you are saying. Now yes, the limelights will indeed be bright and annoying. No denying. However, they aren’t really that bad unless you’re about 5 inches away (please take it from me, don’t do that). I guess if you really want you could bring tinted glasses, or the FTAs can use tinted windows on driver stations, but really you’ll just be okay if you don’t stare right at the light. If you just focus on the camera feed on the computer (or somewhere off to the side so you can use your peripherals) the light won’t blind you, or at least for more than a second or two. There are also software solutions too, but I don’t want to bore y’all about that.

True, being blinded does actually trigger a bit of a safety response as opposed to unknowingly allowing yourself to stare into it for a protracted period of time. So, you’d definitely wouldn’t want students working closely on the robot to just be staring straight into it, anymore than the green LEDs. Is that what you’d be most concerned about or do you think it would be a concern in the game, as well?

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I honestly couldn’t say how overblown the concerns about eye damage are WRT LL or other FRC vision system light sources, but I do know it has been enough of a concern to cause discussion about their legality. TBH, the plexi of the DS wall will likely filter out some of the dangerous light energy, but I wouldn’t bet my eyesight on it.

I just think it’s a dangerous direction for teams to mask the problem by switching to invisible light sources.

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Reminds me of shelfbot at MARC 2…