RoboCupJunior Soccer Rules 2024

RCJ Soccer games consist of two teams of robots playing soccer against each other. Each team has two autonomous robots. The game will consist of two halves. The duration of each half is 10-minutes. There will be a 5-minute break in between the halves.

The game clock will run for the duration of the halves without stopping (except when a referee wants to consult another official). The game clock will be run by a referee or a referee assistant (see Rule 7.1, “Referee and referee assistant” for more information on their roles).

Teams are expected to be at the field 5 minutes before their game starts. Being at the inspection table does not count in favor of this time limit. Teams that are late for the start of the game may be penalized one goal per 30 seconds at the referee’s discretion.

The final game score will be trimmed so that there is at most 10-goal difference between the losing and the winning team.

At the start of the first half of the game, a referee will toss a coin. The team mentioned first in the draw shall call the coin. The winner of the toss can choose either which end to kick towards, or to kick off first. The loser of the toss chooses the other option. After the first half, teams switch sides. The team not kicking off in the first half of the game will kick off to begin the second half of the game.

During the pre-match meeting the referee or their assistant may check whether the robots are capable of playing (i.e., whether they are at least able to follow and react to the ball). If none of the robots is capable of playing, the game will not be played and zero goals will be awarded to both teams.

Each half of the game begins with a kick-off. All robots must be located on their own side of the field. All robots must be halted. The ball is positioned by a referee in the center of the field.

The team kicking off places their robots on the field first.

The team not kicking off will now place their robots on the defensive end of the field. All robots on the team not kicking off must be at least 30 cm away from the ball (outside of the center circle).

Robots cannot be placed out of bounds. Robots cannot be repositioned once they have been placed, except if the referee requests to adjust their placement to make sure that the robots are placed properly within the field positions.

On the referee’s command (usually by whistle), all robots will be started immediately by each captain. Any robots that are started early will be removed by the referee from the field and deemed damaged.

Before a kick-off, all damaged or out-of-bounds robots are allowed to return to the playing field immediately if they are ready and fully functional.

If no robots are present at a kick-off (because they have moved out-of-bounds Rule 1.8, “Out of bounds” or are damaged Rule 1.9, “Damaged robots”), the penalties are discarded and the match resumes with a Rule 1.3.1, “Neutral kick-off”.

A goal is scored when the ball strikes or touches the back wall of the goal. Goals scored by any robot have the same end result: they give one goal to the team on the opposite side. After a goal, the game will be restarted with a kick-off from the team who was scored against.

A robot cannot hold a ball. Holding a ball is defined as taking full control of the ball by removing all of degrees of freedom. Examples for ball holding include fixing a ball to the robot’s body, surrounding a ball using the robot’s body to prevent access by others, encircling the ball or somehow trapping the ball with any part of the robot’s body. If a ball does not roll while a robot is moving, it is a good indication that the ball is trapped.

The only exception to holding is the use of a rotating drum (a "dribbler") that imparts dynamic back spin on the ball to keep the ball on its surface.

Other players must be able to access the ball.

The ball needs to stay within the bounds of the field, as defined by the walls. If a robot moves the ball outside of the field (that is, beyond the walls or above their height), it is deemed damaged. (Rule 1.9, “Damaged robots”)

Any robot must approach and touch the ball when it is placed on the nearest neutral spot. It must do this before lack of progress is called. When on its own side of the field, any robot must be able to move the ball from the nearest neutral spot to the opponent’s side of the field. If a specific robot does not act this way, referees may deem it damaged at their discretion. (See Damaged Robots.) This rule does not apply if the robot is hindered from detecting or playing the ball by the opponent.

No robots are allowed to be fully inside the penalty area. As the penalty areas are marked with a white line, the Out of Bounds and Out of Reach rules apply as well. (Rule 1.8, “Out of bounds”)

If two robots from the same team are at least partially in a penalty area, the robot further from the ball will be moved to the furthest unoccupied neutral spot immediately. If this happens repeatedly, a robot may be deemed damaged at referee’s discretion. (Rule 1.9, “Damaged robots”)

If an attacking and a defending robot touch each other while at least one of them is at least partially inside the penalty area, and at least one of them has physical contact with the ball, this may be called "pushing" at the referee’s discretion. In this case, the ball will be moved to the furthest unoccupied neutral spot immediately.

If a goal is scored as a result of a "pushing" situation, it will not be granted.

Lack of progress occurs if there is no progress in the gameplay for a reasonable period of time and the situation is not likely to change. Typical lack of progress situations are when the ball is stuck between robots, when there is no change in ball and robot’s positions, or when the ball is beyond detection or reach capability of all robots on the field.

After a visible and loud count ^[2], a referee will call lack of progress and will move the ball to the nearest unoccupied neutral spot. If this does not solve the lack of progress, the referee can move the ball to a different neutral spot.

If a robot touches a wall or moves completely into the penalty area it will be called for being out of bounds. When this situation arises, the robot is given a one-minute penalty, and the team is asked to remove the robot from the field. There is no time stoppage for the game itself. The robot is allowed to return if a kick-off occurs before the penalty has elapsed.

The one-minute penalty starts when the robot is removed from play. Furthermore, any goal scored by the penalized team while the penalized robot is on the field will not be granted. Out-of-bounds robots can be fixed if the team needs to do so, as described in Rule 1.9, “Damaged robots”.

After the penalty time has passed, robot will be placed on the unoccupied neutral spot furthest from the ball, facing its own goal.

A referee can waive the penalty if the robot was accidentally pushed out of bounds by an opposing robot. In such a case, the referee may have to slightly push the robot back onto the field.

The ball can leave and bounce back into the playing field. The referee calls out of reach, and will move the ball to the nearest unoccupied neutral spot when one of the following conditions occurs:

If a robot is damaged, it has to be taken off the field and must be fixed before it can play again. Even if repaired, the robot must remain off the field for at least one minute or until the next kick-off is due.

Some examples of a damaged robot include:

Computers and repair equipment are not permitted in the playing area during gameplay. Usually, a team member will need to take the damaged robot to an "approved repair table" near the playing area. A referee may permit robot sensor calibration, computers and other tools in the playing area, only for the 5 minutes before the start of each half.

After a robot has been fixed, it will be placed on the unoccupied neutral spot furthest from the ball, facing its own goal. A robot can only be returned to the field if the damage has been repaired. If the referee notices that the robot was returned to the field with the same original problem, they may ask the robot to be removed and proceed with the game as if the robot had not been returned.

Only the referee decides whether a robot is damaged. A robot can only be taken off or returned with the referee’s permission.

If both robots from the same team are deemed damaged at kick-off, gameplay will be paused and the remaining team will be awarded 1 goal for each elapsed 30 seconds that their opponent’s robots remain damaged. However, these rules only apply when none of the two robots from the same team were damaged as the result of the opponent team violating the rules.

Whenever a robot is removed from play, its motors must be turned off.

Except for the kick-off, human interference from the teams (e.g. touching the robots) during the game is not allowed unless explicitly permitted by a referee. Violating team(s)/team member(s) may be disqualified from the game.

The referee or a referee assistant can help robots get unstuck if the ball is not being disputed near them and if the situation was created from normal interaction between robots (i.e. it was not a design or programming flaw of the robot alone). The referee or a referee assistant will pull back the robots just enough for them to be able to move freely again.

In principle, a game will not be stopped.

A referee can stop the game if there is a situation on or around the field which the referee wants to discuss with an official of the tournament or if the ball malfunctions and a replacement is not readily available.

When the referee has stopped the game, all robots must be stopped and remain on the field untouched. The referee may decide whether the game will be continued/resumed from the situation in which the game was stopped or by a kick-off.

A team must have more than one member to form a RoboCupJunior team to participate in the international competition. Team member(s) and/or robot(s) cannot be shared between teams.

Each team member needs to carry a technical role.

Each team must have a captain. The captain is the person responsible for communication with referees. The team can replace its captain with another team member during the competition. Each team is allowed to have at most two members beside the field during gameplay: they will usually be the captain and an assistant team member.

Each team is allowed to have at most two robots for the full tournament. The substitution of robots during the competition within the team or with other teams is forbidden.

Robots are not allowed to be colored orange, yellow or blue in order to avoid interference. Orange, yellow, blue colored parts used in the construction of the robot must either be occluded by other parts from the perception by other robots or be taped/painted with a neutral color.

Robots must not produce magnetic interference in other robots on the field.

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”

The referee can interrupt a game in progress if any kind of interference from spectators is suspected (IR emitters, camera flashes, mobile phones, radios, computers, etc.). However, robots are expected to be capable of dealing with any visible colors above the walls (e.g. blue, yellow, green or orange shirts) either in hardware (e.g. limiting the field of view from looking up) or in software (e.g. masking the input image).

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 the tournament organizers if a claim is placed by the other team.

The use of remote control of any kind is not allowed during the match. Robots must be started and stopped manually by humans and be controlled autonomously.

Robots are not allowed to use any kind of communication during gameplay unless the communication between robots is via Bluetooth class 2 or class 3 ^[4] or via any other device that communicates using the 802.15.4 protocol (e.g., ZigBee and XBee).

Teams are responsible for their communication. The availability of frequencies cannot be guaranteed.

For only the World Championships, starting in Brazil 2025, use of a Communications Module is required for referees to control the robots. See Rule 9.2, “Competition Gameplay”

Robots must be constructed and programmed in a way that their movement is not limited to only one dimension (defined as a single axis, such as only moving in a straight line). They must move in all directions, for example by turning.

All robots must have a stable and easily noticeable handle to hold and to lift them. The handle must be easily accessible and allow the robot to be picked up from at least 5 cm above the highest structure of the robot.

The dimensions of the handle may exceed the robot height limitation, but the part of the handle that exceeds this limit cannot be used to mount components of the robot.

The weight of the robot includes that of the handle.

A robot must have markings in order to be distinguished by the referee. Each robot must have a white plastic circle with a diameter of at least 4 cm mounted horizontally on top. This white circle will be used by the referee to write numbers on the robots using markers, therefore the white circles must be accessible and visible. The top markers do not need to be within the size limit of the robot.

Before the game, the referee will designate the numbers for each robot and will write them on the top white circle. Robots not carrying the top white circle are not eligible to play.

Robots that do not abide by the specifications/regulations (see Rule 8.2, “Regulations”) are not allowed to play, unless these rules specify otherwise.

If violations are detected during a running game the team may be disqualified for that game.

If similar violations occur repeatedly, the team may be disqualified from the tournament.

See Appendix A, Technical Specification For Soccer Field.

See Appendix B, Technical Specification for pulsed Soccer Ball.

Starting in 2026, Lightweight Soccer will be moving to a new IR Ball. The key difference with this ball is the size change from 74mm to 42mm diameter, which is the same size as the Open League’s Passive ball. More information will be released during the 2025 season by the Committee. This ball is Open-Source, so anyone can produce one from the files & instructions on the GitHub Page here: https://github.com/robocup-junior/ir-golf-ball

See Appendix C, Technical Specification for passive Soccer Ball.

Balls for the tournament must be made available by the tournament organizers. Tournament organizers are not responsible for providing balls for practice.

It is expected that the aim of all teams is to play a fair and clean game of robot soccer. It is expected that all robots will be built with consideration to other participants.

Robots are not allowed to cause deliberate interference with or damage to other robots during normal gameplay.

Robots are not allowed to cause damage to the field or to the ball during normal gameplay.

A robot that causes damage may be disqualified from a specific match at the tournament organizer’s discretion.

Humans are not allowed to cause deliberate interference with robots or damage to the field or the ball.

Teams that do not abide by the rules are not allowed to participate.

All participants are expected to behave themselves. All movement and behavior is to be of a subdued nature within the tournament venue.

Mentors (teachers, parents, chaperones, and other adult team-members including translators) are not allowed in the student work area unless it is explicitly but temporarily permitted by tournament organizers. Only participating students are allowed to be inside the work area.

Mentors must not touch, build, repair, or program any robots.

The understanding that any technological and curricular developments should be shared among the RoboCup and RoboCupJunior participants after the tournament has been a part of world RoboCup competitions.

It is expected that all participants, students, mentors, and parents will respect the RoboCupJunior mission.

It is not whether you win or lose, but how much you learn that counts!

Teams that violate the code of conduct may be disqualified from the tournament. It is also possible to disqualify only single person or single robot from further participation in the tournament.

In less severe cases of violations of the code of conduct, a team will be given a warning. In severe or repeated cases of violations of the code of conduct a team may be disqualified immediately without a warning.

The referee is a person in charge of making decisions with regards to the game, according to these rules, and may be assisted by a referee assistant.

During gameplay, the decisions made by the referee and/or the referee assistant are final.

Any argument with the referee or the referee assistant can result in a warning. If the argument continues or another argument occurs, this may result in immediate disqualification from the game.

Only the captain has a mandate to freely speak to the referee and/or their assistant. Shouting at a referee and/or their assistant, as well as demanding a change in ruling may be penalized by a warning at the referee’s discretion.

At the conclusion of the game, the result recorded in the scoresheet is final. The referee will ask the captains to add written comments to the scoresheet if they consider them necessary. These comments will be reviewed by the tournament organizers.

Rule clarification may be made by members of the tournament organizers and the Soccer League Committee, if necessary even during a tournament.

If special circumstances, such as unforeseen problems or capabilities of a robot occur, rules may be modified by the tournament organizers, if necessary even during a tournament.

Each RoboCupJunior competition may have its own regulatory statutes to define the procedure of the tournament (for example the SuperTeam system, game modes, the inspection of robots, interviews, schedules, etc.). Regulatory statutes become a part of this rule.

According to rule 3.8 of the RoboCupJunior Soccer Rules, each league has its own additional regulations. They become a part of the rules.

For RoboCupJunior , there are two sub-leagues as follows ^[5]:

All team members need to be within the age range specified in the RoboCupJunior General Rules which can be found at http://junior.robocup.org/robocupjunior-general-rules/.

As described in Rule 5.1, “Specification for Soccer Lightweight Ball” and Rule 5.2, “Specification for Soccer Open Ball”, the matches in the Soccer Open sub-league are conducted using a passive ball, whereas the matches in the Soccer Lightweight sub-league are played using the IR ball.

Maximum team size is 4 members for RoboCupJunior Soccer.

This rule has been removed from 2025 onwards. ^[7]

Starting from the 2025 International Competition in Brazil, the Soccer League Committee will provide each team with a Communication Module. This allow for easier co-ordination of games and referee control of robots during matches. Each team will be expected to interface with this module using a single 2.54mm GPIO pin at present to start and stop the robots. The Soccer League Committee plans on extending this to using UART or I²C for more complex applications in future years. Please see the GitHub page for more information on the module: https://github.com/robocup-junior/soccer-communication-module

During the international competition, the tournament organizers will arrange to interview teams during the Setup Day of the event. This means that the teams need to be already present early on this day. Teams must bring robots, the code that is used to program them and any documentation to the interview.

During an interview, at least one member from each team must be able to explain particularities about the team’s robots, especially with regards to its construction and its programming. An interviewer may ask the team for a demonstration. The interviewer may also ask the team to write a simple program during the interview to verify that the team is able to program its robot.

All teams are expected to be able to conduct the interview in English. If this poses a problem, the team may ask for a translator to be present at the interview. If the tournament organizers are not able to provide a translator, the team is required to do so. During the interview, the team will be evaluated using so called Rubrics, which are published on the website mentioned in the beginning of these rules.

The Soccer League Committee recommends the implementation of interviews in regional competitions as well, but this is not mandatory.

Inspired by the major leagues and the need for further technological advancement of the leagues, the Soccer League Committee runs what are called Technical Challenges. New challenges are added each year, and are unknown until during the International Competition.

The idea of these challenges is to give the teams an opportunity to show off various abilities of their robots which may not get noticed during the regular games. Furthermore, the Soccer League Committee envisions these challenges to be a place for testing new ideas that may make it to the future rules, or otherwise shape the competition.

Any RoboCupJunior Soccer team will be eligible to try to tackle these challenges. Unless otherwise stated, any robot taking part in these challenges needs to abide by these rules in order to successfully complete it.

All teams qualified to the international competition must share their designs, both hardware and software, with all present and future participants. These teams are also required to send a digital portfolio before the competition. Further details on how will be provided by the Soccer League Committee which acts as the tournament organizers for the international competition.

During the competition days of the international competition (as well as before the event) the team members are responsible for checking all relevant information published by the Soccer League Committee or any other RoboCup official.

There will also be a SuperTeam competition, in which various teams from around the world share their robots in one "SuperTeam" and play against other SuperTeams on a so called "Big Field". Teams could utilise different camera lenses or sensors optimised for the larger playing fields to improve their performance. The full rules of this challenge can be found at https://robocup-junior.github.io/soccer-rules/master/superteam_rules.html

Teams competing in the international competition can receive awards for their performance. These awards are decided and introduced by the Soccer League Committee, which publishes all necessary details well before the actual event. In the past years they were awarded for best poster, presentation, robot design, team spirit and individual games.

Note that as stated in Rule 6.5, “Spirit”, it is not whether you win or lose, but how much you learn that counts!

The playing field is 158 cm by 219 cm. The field is marked by a white line which is part of the playing field. Around the playing field, beyond the white line, there is an outer area of 12 cm in width.

The floor near the exterior wall includes a wedge, which is an incline with a 10 cm base and 2 +/- 1 cm rise for allowing the ball to roll back into play when it leaves the playing field. Note that the goal should not contain the wedge.

Total dimensions of the field, including the outer area, are 182 cm by 243 cm.

Walls are placed all around the field, including behind the goals and the out-area. The height of the walls is 22 cm. The walls are painted matte black.

The field has two goals, centered on each of the shorter sides of the playing field. The goal inner space is 60 cm wide, 10 cm high and 74 mm deep, box shaped.

The goal "posts" are positioned over the white line marking the limits of the field.

The interior walls and of each goal are colored matte, one goal yellow and the other goal blue. It is recommended that the blue be of a brighter shade so that it is different enough from the black exterior.

The floor consists of green carpet ideally of darker shade on top of a hard level surface. Teams should be prepared to adjust to different levels of contrast between the green carpet and lines as some events may be restricted to using lighter shades of green. All lines on the field should be painted, marked with tape, or installed as white carpet and be somewhat resistant to tearing or ripping. Lines should have a width of 20mm (±10%).

It is impractical to set international constraints on carpet other than it being green. In the spirit of the competition, teams should design robots to be tolerant or adaptable to different fibers, textures, construction, density, shades, and designs of carpet especially when competing amongst different regions. Teams are encouraged to visit regional resources or reach out to Local Organization Committee for suggestions if desiring to build their own practice field(s).

There are five neutral spots defined in the field. One is in the center of the field. The other four are adjacent to each corner, located 45 cm along the long edge of the field. They align with the sides of the penalty areas. The neutral spots can be drawn with a thin black marker. The neutral spots ought to be of circular shape measuring 1 cm in diameter.

A center circle will be drawn on the field. It is 60 cm in diameter. It is a thin black marker line. It is there for Referees and Captains as guidance during kick-off.

In front of each goal there is a 25 cm wide and 80 cm long penalty area with rounded front corners (15cm radius).

The penalty areas are marked by a white line of 20 mm (±10%) width. The line is part of the area.

The tournament organizers will do their best to limit the amount of external lightning and magnetic interference. However, the robots need to be constructed in a way which allows them to work in conditions that are not perfect (i.e. by not relying on compass sensors or specific lightning conditions).

Answering to the request for a soccer ball for RCJ tournaments that would be more robust to interfering lights, less energy consuming and mechanically more resistant, the Soccer League Committee defined the following technical specifications with the special collaboration from EK Japan and HiTechnic.

Producers of these balls must apply for a certification process upon which they can exhibit the RCJ-compliant label and their balls used in RCJ tournaments.

Balls with these specifications can be detected using specific sensors but also common IR remote control receivers (TSOP1140, TSOP31140, GP1UX511QS, etc. - on-off detection with a possible gross indication of distance).

Currently, there is one ball that has been approved by the Soccer League Committee:

Note that this ball was previously called RCJ-05. While you may not be able to find a ball with this name anymore, any IR ball produced by EK Japan/Elekit is considered to be approved by the Soccer League Committee.

In order to push the state of the art in the Soccer competition forward, while also trying to bridge the gap between the Junior and Major leagues, the Soccer League Committee chose a standard orange golf ball as the "passive" ball. This is the same choice as the Small Size League makes ^[10] and since these balls are standardized, they should be cheap and easy to get anywhere around the globe.