An interview with Nicolai Ommer: the RoboCupSoccer Small Dimension League

Kick-off in a Small Dimension League match. Picture credit score: Nicolai Ommer.

RoboCup is a global scientific initiative with the objective of advancing the state-of-the-art of clever robots, AI and automation. The annual RoboCup occasion is because of happen from 15-21 July in Salvador, Brazil. The Soccer element of RoboCup includes quite a few Leagues, with one in all these being the Small Dimension League (SSL). We caught up with Govt Committee member Nicolai Ommer to seek out out extra in regards to the SSL, how the auto referees work, and the way groups use AI.

May begin by giving us a fast introduction to the Small Dimension League?

Within the Small Dimension League (SSL) now we have 11 robots per group – the one bodily RoboCup soccer league to have the total variety of gamers. The robots are small, cylindrical robots on wheels they usually can transfer in any course. They’re self-built by the groups, so groups should do each the {hardware} and the programming, and a whole lot of issues should work collectively to make a group work. The AI is central. We don’t have brokers, so groups have a central laptop on the area the place they’ll do all of the computation after which they ship the instructions to the robots in numerous abstractions. Some groups will simply ship velocity instructions, different groups ship a goal.

We have now a central imaginative and prescient system – that is maintained by the League, and has been since 2010. There are cameras above the sector to trace all of the robots and the ball, so everybody is aware of the place the robots are.

The robots can transfer as much as 4 meters per second (m/s), after this level it will get fairly unstable for the robots. They’ll change course in a short time, and the ball will be kicked at 6.5 m/s. It’s fairly quick and we’ve already needed to restrict the kick pace. Beforehand we had a restrict of 8 m/s and earlier than that 10m/s. Nonetheless, no robotic can catch a ball with this pace, so we determined to scale back it and put extra concentrate on passing. This provides the keeper and the defenders an opportunity to truly intercept a kick.

It’s so quick that for people it’s fairly obscure all of the issues which are happening. And that’s why, some years in the past, we launched auto refs, which assist quite a bit in monitoring, particularly issues like collisions and so forth, the place the human referee can’t watch the whole lot on the identical time.

How do the auto refs work then, and is there a couple of working on the identical time?

Once we developed the present system, to maintain issues truthful, we determined to have a number of implementations of an auto ref system. These unbiased techniques implement the identical guidelines after which we do a majority vote on the choices.

To do that we would have liked a center element, so some years in the past I began this undertaking to have a brand new sport controller. That is the consumer interface (UI) for the human referee who sits at a pc. Within the UI you see the present sport state, you’ll be able to manipulate the sport state, and this element coordinates the auto refs. The auto refs can join and report fouls. If just one auto ref detects the foul, it gained’t depend it. However, if each auto refs report the foul throughout the time window, then it’s counted. A part of the problem was to make this all visible for the operator to know. The human referee has the final phrase and makes the ultimate choice.

We managed to ascertain two implementations. The purpose was to have three implementations, which makes it simpler to type a majority. Nonetheless, it nonetheless works with simply two implementations and we’ve had this for a number of years now. The implementations are from two completely different groups who’re nonetheless lively.

How do the auto refs take care of collisions?

We will detect collisions from the info. Nonetheless, even for human referees it’s fairly arduous to find out who was at fault when two robots collide. So we needed to simply outline a rule, and all of the implementations of the auto ref implement the identical rule. We wrote within the rulebook actually particularly the way you calculate if a collision occurred and who was at fault. The primary consideration relies on the speed – beneath 1.5m/s it’s not a collision, above 1.5m/s it’s. There may be additionally one other issue, regarding the angle calculation, that we additionally have in mind to find out which robotic was at fault.

What else do the auto refs detect?

Different fouls embody the kick pace, after which there’s fouls regarding the adherence to regular sport process. For instance, when the opposite group has a free kick, then the opposing robots ought to preserve a sure distance from the ball.

The auto refs additionally observe non-fouls, in different phrases sport occasions. For instance, when the ball leaves the sector. That’s the most typical occasion. This one is definitely not really easy to detect, notably if there’s a chip kick (the place the ball leaves the taking part in floor). With the digicam lens, the parabola of the ball could make it appear like it’s outdoors the sector of play when it isn’t. You want a strong filter to take care of this.

Additionally, when the auto refs detect a objective, we don’t belief them utterly. When a objective is detected, we name it a “attainable objective”. The match is halted instantly, all of the robots cease, and the human referee can examine all of the accessible information earlier than awarding the objective.

You’ve been concerned within the League for quite a few years. How has the League and the efficiency of the robots advanced over that point?

My first RoboCup was in 2012. The introduction of the auto refs has made the play much more fluent. Earlier than this, we additionally launched the idea of ball placement, so the robots would place the ball themselves for a free kick, or kick off, for instance.

From the {hardware} facet, the principle enchancment in recent times has been dribbling the ball in one-on-one conditions. There has additionally been an enchancment within the specialised abilities carried out by robots with a ball. For instance, some years in the past, one group (ZJUNlict) developed robots that would pull the ball backwards with them, transfer round defenders after which shoot on the objective. This was an surprising motion, which we hadn’t seen earlier than. Earlier than this you needed to do a move to trick the defenders. Our group, TIGERs Mannheim, has additionally improved on this space now. But it surely’s actually tough to do that and requires a whole lot of tuning. It actually will depend on the sector, the carpet, which isn’t standardized. So there’s slightly little bit of luck that your particularly constructed {hardware} is definitely performing effectively on the competitors carpet.

The Small Dimension League Grand Ultimate at RoboCup 2024 in Eindhoven, Netherlands. TIGERs Mannheim vs. ZJUNlict. Video credit score: TIGERs Mannheim. Yow will discover the TIGERs’ YouTube channel right here.

What are a few of the challenges within the League?

One huge problem, and in addition perhaps it’s an excellent factor for the League, is that now we have a whole lot of undergraduate college students within the groups. These college students have a tendency to go away the groups after their Bachelor’s or Grasp’s diploma, the group members all change fairly frequently, and that implies that it’s tough to retain data within the groups. It’s a problem to maintain the efficiency of the group; it’s even arduous to breed what earlier members achieved. That’s why we don’t have massive steps ahead, as a result of groups should repeat the identical issues when new members be part of. Nonetheless, it’s good for the scholars as a result of they actually study quite a bit from the expertise.

We’re repeatedly engaged on figuring out issues which we are able to make accessible for everybody. In 2010 the imaginative and prescient system was established. It was an enormous issue, which means that groups didn’t should do laptop imaginative and prescient. And we’re at present taking a look at establishing requirements for wi-fi communication – that is at present executed by everybody on their very own. We need to advance the League, however on the identical time, we additionally need to have this nature of with the ability to study, with the ability to do all of the issues themselves in the event that they need to.

You really want to have a group of individuals from completely different areas – mechanical engineering, electronics, undertaking administration. You additionally should get sponsors, and you must promote your undertaking, get college students in your group.

May you discuss a few of the AI parts to the League?

Most of our software program is script-based, however we apply machine studying for small, delicate issues.

In my group, for instance, we do mannequin calibration with fairly easy algorithms. We have now a selected mannequin for the chip kick, and one other for the robotic. The wheel friction is kind of sophisticated, so we give you a mannequin after which we accumulate the info and use machine studying to detect the parameters.

For the precise match technique, one good instance is from the group CMDragons. One yr you would actually observe that they’d skilled their mannequin in order that, as soon as they scored objective, they upvoted the technique that they utilized earlier than that. You could possibly actually see that the opponent reacted the identical approach on a regular basis. They had been in a position to rating a number of targets, utilizing the identical technique repeatedly, as a result of they realized that if one technique labored, they might use it once more.

For our group, the TIGERs, our software program may be very a lot based mostly on calculating scores for the way good a move is, how effectively can a move be intercepted, and the way we are able to enhance the state of affairs with a specific move. That is hard-coded generally, with some geometry-based calculations, however there may be additionally some fine-tuning. If we rating a objective then we observe again and see the place the move got here from and we give bonuses on a few of the rating calculations. It’s extra sophisticated than this, in fact, however basically it’s what we attempt to do by studying in the course of the sport.

Folks typically ask why we don’t do extra with AI, and I believe the principle problem is that, in comparison with different use instances, we don’t have that a lot information. It’s arduous to get the info. In our case now we have actual {hardware} and we can’t simply do matches all day lengthy for days on finish – the robots would break, they usually must be supervised. Throughout a contest, we solely have about 5 to seven matches in whole. In 2016, we began to report all of the video games with a machine-readable format. All of the positions are encoded, together with the referee choices, and the whole lot is in a log file which we publish centrally. I hope that with this rising quantity of knowledge we are able to truly apply some machine studying algorithms to see what earlier matches and former methods did, and perhaps get some insights.

What plans do you’ve on your group, the TIGERs?

We have now truly gained the competitors for the final 4 years. We hope that there will probably be another groups who can problem us. Our defence has not likely been challenged so now we have a tough time discovering weaknesses. We truly play in opposition to ourselves in simulation.

One factor that we need to enhance on is precision as a result of there may be nonetheless some guide work to get the whole lot calibrated and dealing as exactly as we would like it. If some small element is just not working, for instance the dribbling, then it dangers the entire match. So we’re engaged on making all these calibration processes simpler, and to do extra computerized information processing to find out the perfect parameters. In recent times we’ve labored quite a bit on dribbling within the 1 vs 1 conditions. This has been a extremely huge enchancment for us and we’re nonetheless engaged on that.

About Nicolai

Nicolai Ommer is a Software program Engineer and Architect at QAware in Munich, specializing in designing and constructing sturdy software program techniques. He holds a B.Sc. in Utilized Laptop Science and an M.Sc. in Autonomous Techniques. Nicolai started his journey in robotics with Workforce TIGERs Mannheim, taking part in his first RoboCup in 2012. His dedication led him to affix the RoboCup Small Dimension League Technical Committee and, in 2023, the Govt Committee. Captivated with innovation and collaboration, Nicolai combines educational perception with sensible expertise to push the boundaries of clever techniques and contribute to the worldwide robotics and software program engineering communities.