Suggestions for the lightweight league #soccer-rules-2024

Hi RoboCup Forum,

I want to reopen the discussion for the soccer lightweight rule changes introduced by @remosgro in his post last year.
He wants to move away from the IR-Ball and reduce the diameter of the robot. His arguments for these changes are the lack of new teams in the lightweight league as seen during the last few years.
As I do soccer lightweight myself, I see his points and would love some significant changes to the lightweight league for next year.
Let me explain why:
The lightweight league is technically the same since the introduction. Only slight changes and little adjustments were made. There are many teams out there using commercial kits and/or robots who are in development for many years now. I saw all this at the World Open last week and at the German Open. Many teams use the same robot design with just insignificant changes for many years now. This prohibits teams of entering the lightweight league and the number of teams will drop increasingly. Many teams are already preferring the traditionally more advanced open league.

With the inspiration of @remosgro I suggest following changes:

  • Drop of the IR-Ball
  • Introduction of new colored Ball (I am still searching for a proper replacement, which is easily available all over the world)
  • Increasing the weight limit to 1200g
  • Drop of IR restrictions
  • Wi-Fi legitimation (as already mentioned here)

I also would like to provide some arguments:

  • As already mentioned, there were no significant rule changes for the lightweight league for many years now and teams reuse designs or whole robots for many years now.
    Because of this, the skill level is much higher than in the open league.
  • Nowadays, camera systems are easy to implement and are not that expensive anymore (see the pixy 2.1).
    Due to the drop of camera restrictions, there are many new possibilities for the teams to develop or if necessary, buy 360° camera systems.
  • As @david mentioned in his response to @remosgro , the production of IR Balls is not safe and changing concepts now, way ahead before the first national competition is easier than adapting in a brief period.
  • With cameras there will also be the possibility for more accurate movement, since the direction towards the ball is known, more precise than with every infrared sensor.
  • It would also allow teams to use accurate distance measurements systems, such as time of light or lidars. There sensors are currently banned in the soccer light weight league due their interference with the IR seekers.
  • No more interference from other leagues. All the rescue major teams use multi-layer lidar sensors who directly interfere with a lot of IR seekers. Using a camera instead would solve a lot of these problems.
  • Also, the aim of the RoboCup is to encourage technological improvements, and with still standing rules and no need for substantial changes in the overall robot design, this is not possible.
  • A minor increase in the weight of the robot would help a lot with the implementation of a more extensive camera system. We could evaluate if 100g more is necessary and if needed change it back to the traditional 1100g.

I hope I could provide some insights in my thinking progress, and I hope these suggestions will be discussed by the official soccer committee.

Robotics Club of the Lessing Gymnasium Neu-Ulm [Germany]

This is the main reason we moved away from the previous colored ball.

We are not fully certain this is just from experience. Major changes are going to have to be 2025 though because we run on a tik/tok cycle where one year we do major changes and the next we try to keep them smaller.

There is now fortunately at least an open source ball design where the shell is printed on an SLA printer and the PCB can cheaply be ordered at e.g. PCBway, Aisler or similar sources.

While that is correct making both leagues the same would also be pointless.

The weight limit may be a good discussion point. I will put up a separate discussion thread for that. Proper kickers might also benefit from a couple extra grams and it could reduce difficulty for new teams coming in.

I don’t have fully cohesive thoughts on this yet, maybe other people (I’d particularly be interested in reports from mentors with inexperienced LWL teams as to where the difficulties are).


Hi David,
hi everybody,

thanks for your input David.
I didn’t knew about this cycle of rule changes. I am happy to see some of my points being discussed in other threads and I would love to reopen this discussion for the 2025 rules.

Robotics Club of the Lessing Gymnasium Neu-Ulm [Germany]

Hi Elias,

in saying that we’re not looking to make major changes in 2024 I did not want to postpone the discussion immediately. We are on a relatively short timeline between the competition and releasing “beta” rules (i.e. draft rules that won’t get any more big changes) and having the discussion now and continuing it over the course of the year so we have somewhat settled ideas by the time the next set of rules needs to be created is probably the only way we are going to arrive at a cohesive set of rules with changes that major. As there are >1000 soccer teams globally from hundreds of institutions (schools and clubs mostly) we have to be careful not to make it very hard on teams and schools with little resources by making lots of major changes all the time, this is where the “not big changes every year” scheme comes from.

Could you maybe describe the effect you would expect these changes to have some more? @remosgro what do you think of this proposal?


Hi Elias,
I can see all your points and I agree to most of them.
But a drop of the IR Ball (including the drop of all ir-sensor restrictions)
would make the lightweight league almost the same as the open league with the only difference
that if the robot is light enough it could start at lightweight and if not it would start at open.
So sticking to the IR ball will keep the lightweight league placed beneath the open league and keeps the “gap” from 1vs1 small enough for teams to go the step to 2vs2.

The next idea is definitely not for 2024 but for 2025 and if we want to apply this change we have to announce it this year:
If we invent and build a new IR ball which would be at least partly DIY, why should we stick to the size of the old ball?

What about an golf-ball sized IR ball?
Possibly with a blurred surface that you do not have spotlight IR beams but an IR shining ball.
This would offer lots of rule changes for the next years like diameter and size changes.

As far as I know (and I have seen Jakubs IR Ball in Varazdin) it is probably easier to produce this kind of IR ball than to try copying the existing one.
With a blurred surface we do not need so many IR-LEDS and we could also use small Lipo batteries instead of AAA batteries.

It would keep the simplicity of detecting the ball but offers lots of inventions.
And as you mentioned in your post, teams could not simply recycle their old robots if the IR ball is smaller and the diameter of the robot is reduced as well.

What do you think?

Hi everyone,

I substantially agree with proposal, except perhaps regarding Wifi permission.

I think it’s time to change Lightweight rules, a major change should normally produce two main effects:

  • raising the technical level.

  • to restart game, so that the new teams have the same chance as the old ones to compete successfully

There are two main points under discussion:

  • type/color/dimension of the ball

  • dimension of the robot

The first affect the second one. If we want to reduce the robot’s dimension, and I think is a god idea, similar to what was done in the Open category, the effect is to enlarge the game field, we have to reduce ball dimension. Last year I suggested to use the previous orange ball from the Open. However, if we still want to use IR ball we have to try to redesign a smaller one.

Raimondo Sgrò

IIS Cobianchi - Italy

We are somewhat hesitant of raising the technical level because it is currently fairly hard for new teams to join. Do you think raising the weight limit (thread here) would help to reduce the advantage gained from lots of experience? We were thinking of going to 1400g in the 2024 season for reasons explained int he other thread.

In principle we agree that an LWL overhaul is probably due but before we commit to going to cameras we need more mentors/teachers’ experience to show that it is not just also practical but actually easier for new teams to get started on cameras, particularly to make sure we get a good transition into 2v2 from the 1v1 Entry LW and Entry Standard Kit leagues that are running in many regions. Any ideas would be greatly appreciated

This could also be an option but would require producing and distributing that ball at hundreds/thousands scale, would require hundreds of schools to acquire the new ball and to do a bunch of completely new parts. Also: Big ball for Entry still probably?

With Lego now not being an option for beginners in LWL and the availability of the IR ball dwindling, should we seriously consider how the leagues progress?

With cameras now being on a similar level to the HiTechnic IR Tracker in both price and complexity, it seems feasible to make entry and the sub-league designed for novices use a passive ball (I have the opportunity test out starting a rookie group of students with Open this season but would like to hear what others think). If the golf ball is too small for beginners, we could start entry with an orange street hockey ball similar to what it was originally. The higher weight limit makes it easier to select cheaper motors and batteries but the size constraint may need to be swapped with LWL.

The advance sub-league could then use an active ball that may require construction (e.g. they are given PCB designs and 3D models) along with having tighter constraints on weight and dimensions.

I bring this up here to see if suggestions for changes to LWL may change this season if for 2025 Open became the beginner’s league and LWL is now the advanced league. We could also delve into this more in a separate thread if there is significant interest here for this change.


The increasing of technical level should be combined with “restarting game”.

Yes, I concur with the 1.4kg limit for LWL; it’s a good solution (and aid) for newcomers. However, I remain convinced that we also need to implement some substantial changes.

You’re right, we do. The reason we’re not doing that this year is two-fold:

  • We did a major change requiring field rebuilds etc. last year and always try not to do major changes in back-to-back years.
  • We would like to develop those major changes over a longer period of time together with the community. Therefore we’ll take the time to keep this discussion going throughout the season so we can get as wide a spectrum of inputs as possible and everybody can be forewarned that bigger changes are coming for next season. I’ll suggest we put a note into the rules that we are working on major changes for 2025 to encourage feedback from everybody reading the rules.

Hi everyone who is following this thread, we’re having an open committee meeting on the topic of 2025+ developments Sep. 13th, see Soccer Rules Open Meetings #soccer-rules-2024

We will post stuff talked about on the call back to the forum because we know not everybody will be able to make it to the meeting and please do continue discussing here, there have been a lot of good ideas already and we’ll continue developing 2025+ changes throughout the season.

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