LEDs in LWL - PR#80 2023 Draft Rules

A conversation has started around the pull request (link here) intended to clarify the previous rule that LWL robots shall not emit IR light. The intended update is:

Components designed to emit IR (e.g. IR time-of-flight LiDAR sensors) are not allowed and tournament organizers will require such devices to be removed or covered up. Any device designed to emit light of any wavelength must be mounted so that light is directed perpendicular to the playing field or be covered/removed. If there are any concerns about a potential design violating these rules, please search the forum and post any questions if any necessary clarifications are not found.

The comment in question is:

We use a photocell with an LED to detect the presence of the ball in the capturing zone. The light barrier is tangential to the robot, i.e. arranged parallel to the playing field. The LEDs are red or green far from IR. The new rules should take this into account.

Please keep any replies in this thread related only to the bolded section above (the IR clarification is currently being discussed in this thread).

Here is the relevant section in the current rules regarding interference with the most relevant sentence in bold:

Robots must not produce visible light that may prevent the opposing team from playing when placed on a flat surface. Any part of a robot that produces light that may interfere with the opposing robot’s vision system must be covered. For Lightweight-specific regulations see Rule 8.2.2, “Infrared interference in Lightweight”

A team claiming that their robot is affected by the other team’s robot in any way must show the proof/evidence of the interference. Any interference needs to be confirmed by an OC member if a claim is placed by the other team.

Given that a LED designed to emit visible light may produce light in the range of sensitivity for any IR sensor, how may we clarify this rule to be reasonably confident that it does not allow for designs that could interfere with IR ball detection? Is it reasonable to only restrict devices designed to emit IR and then rely on the current light interference rule for all other situations?

I know of 3 cases where the rule causes problems.

  1. Light barrier for ball detection.
  2. light barrier as a limit switch for the shot.
  3. Light barrier for encoder at the drive.

My suggestion is to make an exception for light barriers if the light from the light barrier LED cannot leave the robot.

I don’t understand why case 80 has already been closed

It has been closed because the branch it came from has accidentally been pushed to with other changes so it wasn’t just that change anymore. We ended up merging https://github.com/RoboCupJuniorTC/soccer-rules/pull/93. It basically only contains more examples of parts that emit IR and not the limitations on other light.

Sorry for the confusion, we merged a bunch of PRs in yesterdays meeting as today is our deadline for final rules and instead of fixing PR #80 we opted to quickly make a new one with the cut-down change we actually wanted to merge. I hope this clears it up and more importantly I hope the phrasing that only prohibits IR-emitting parts and no longer prohibits all light that’s not pointing straight up or straight down solves your issue.

Best Regards