Mini Sumo

These rules may not be the final ones, the organizers have the right to modify them as they see fit. If there are any changes we'll let you know at once.

    Two robots compete on a circular ring (dohyo). Before the start, they are placed to a predefined position. When the match is started, they try to push one another out of the ring. If a robot or any part of it touches the ground outside of the ring, the robot loses. This also applies in case any part of the robot falls and is pushed by the opponent out of the ring or falls off the ring by itself. The first robot who wins two rounds, wins the match.

    1. General Requirements
      1. Autonomous Sumo robots are self-propelled and self-controlled. After positioning and starting the robot, no remote control, power, positioning, or other help can be provided. The robot must care for itself until the round ends. As long as all requirements are met, sumo robots can be made out of any material. They can use any type or size of electric motor or electric-powered locomotion. They can contain any kind of processor, electronics, sensors, or batteries desired. The robot may be altered between matches (not rounds) as long as the rules are followed. Any physical alteration of the robot must be reported to the referee for approval before its next match. Alteration of the software does not have to be reported;
      2. Robots must be equipped with a start/stop system controlled by a remote control( you will find details about this start/stop system in the Start/ Stop documentation). It is the responsibility of the team to implement such a system which will be verified by the referee at the inspection phase. If the robot does not have such a system the team will be disqualified.
    2. Restrictions
      1. Parts that could break or damage the ring are not allowed. Do not use parts that are intended to damage the opponent’s robot or its operator. Normal pushes or bangs are not considered intent to damage;
      2. Devices that can store liquid, powder, gas or other substances for throwing at the opponent are not allowed;
      3. Any flaming devices are not allowed;
      4. Do not use anchoring devices such as vacuum fans, magnets or suction cups;
      5. Devices that throw things at the opponent are not allowed;
      6. During inspection (and at any time during the event), the referee may require safety changes or other modifications to meet the harmlessness requirement. Possibly harmful robots are either not allowed to compete at all or are later disqualified if potential harmful issues are proven in battle;
      7. The referee also examines to see if a robot’s design is sufficient to survive the expected pushing, shoving, and physical rigors of competition.

    1. The sumo ring is a round board called dohyo, with a diameter of 82 cm (820 mm), including the white border;
    2. The border line is marked as a white circular ring with a width of 2.5 cm (25 mm);
    3. The surface is painted matt black, except for the white border;
    4. Around the arena, on a range of at least 100 centimeters the space must not contain any foreign object, any people, lights or anything else;
    5. Thickness: 18 mm.

    1. Robots must have a total mass of 0.5 kg or less and 10 centimeters or less in width and 10 centimeters or less in depth in the conventional start position. There is no height limit;
    2. The teams that cannot prove the functionality of the robot in the given conditions are disqualified.

    1. General aspects
      1. A round is never more than 3 minutes long, unless extended by the referee. If no robot leaves the course before the time is up the round is declared a draw;
      2. One match will consists of 3 rounds. The team who wins two rounds will win the match;
      3. When the match is not won by either team within the time limit, an extended match may be fought. Alternatively, the winner of the match will be the robot with the lower weight. If the weights are equal the winner will be decided by the referee;
      4. If the robots get stuck, they will be stopped after 10 seconds and the game will be restarted. If at the second attempt the robots get stuck, the match will end in a draw;
      5. If one of the two robots won’t start, a restart will be done. If at this restart the same robot won’t start, the match will be won by the robot that moves.
    2. Competition
      1. Course of the Competition
        • Mini Sumo will work by the rule of single-elimination (the loser of each match-up is immediately eliminated from the competition);
        • Robots will compete against each other in groups. Depending on the number of participants, rounds may be divided in eighth-finals/quarter-finals/semifinals/finals;
        • Each match will be supervised by the referee. The decisions of the referee are final, questioning those decisions leads to disqualification;
        • The order of the robots in the groups will be made random and it will be made after the official opening of the competition. The ones that pass the groups will play quarter/semifinals/finals. If the number of the participants will not be enough for the groups the competition will be played from the beginning using pyramidal system. The position in the pyramid will be random;
        • During the whole contest, a team has the right at 2 interruptions for reprogramming, 5 minute each. Other breaks are allowed only for mechanical problems and only with referee’s approval. This rule is applied only during a running match. Besides the matches, the changes and reprogramming are allowed. The teams are required to be at the start in maximum 1 minute from the request, otherwise they will lose the match;
        • During a match, only one representative from each team is allowed to manipulate the robot, the rest of the members of the team will follow the game from the audience.
      2. Inspection
        The first inspection made by the referee happens at the beginning of every match.
        • The referee has the right to do additional inspections of the robots at any time they see fit during the competition;
        • The referee will verify if the robot has a start/stop system by testing it. If the robot does not have such a system the team will be disqualified;
        • The referee has the right to demand changes to the robot if it does not fit with the rules;
        • If the contestant cannot perform the changes that are required, he may lose the round, the match or in extreme cases may be disqualified from the competition;
        • For width and depth, a measured box is placed over the robot.
      3. Positioning
        At the Instructions of the referees, both teams are approaching the ring to put robots on the contest area. A cross with two opposing arrows placed in the middle, divides the sumo ring into four quadrants . Robots always must be placed in two opposite quadrants. The robots must be placed at the edge assigned quadrant. Robots must cover at least partially the white edge. After positioning the robots, the cross is removed, and then robots cannot be moved anymore.
      4. Start. Stop. Continue the match
        For safety reasons, the robots must be equipped with a sensor off (IR) which will be operated by the judges. When the referee will send a stop signal, the supplying of the engines must be cut. The sensor will be used also to power simultaneous both robots, by the referee. The specifications for the sensor on/ off are in the Start/Stop documentation.
        Start, interruption or continuation of the match are announced by the referee.
      5. Out
        • A robot loses a round when any portion (including touch sensors, whiskers, scoops, or skirts) of the robot touches outside of the ring. It doesn’t matter if the robot falls out on its own or is pushed out;
        • The first robot touching outside of the ring loses, even if the second robot subsequently touches outside of the ring. If the referee determines that both robots touched outside of the ring at the same time, the round is nullified and started over;
        • Touching the raised edge of the wall itself is also considered out;
        • If any piece of the robot, no matter how small or even if detached, touches outside of the ring, the robot is considered out. For example, if a nut drops off a robot within the ring, the robot doesn’t immediately lose. However, if the nut is then pushed out or rolls out, the robot loses.
        • Starting to fall or breaking the plane of the ring isn’t considered out. Some portion of the robot must actually touch outside the ring for it to be considered out.
      6. Contestant stoppage
        • At any time a contestant may choose to enter the exterior space or otherwise signal stoppage to the referee. That contestant’s robot loses the round;
        • If the robot is malfunctioning or in a position in which damage could occur, it might be in the contestant’s interest to halt the round and take the short-term loss;
        • A contestant that communicates with a robot, attempts to distract (such as with an IR or laser emitter), or in any way attempts to interfere with the outcome is also considered signaling stoppage.
      7. Referee stoppage
        At the referee’s discretion, the referee may choose to restart a round if:
        • Three minutes have expired;
        • No progress has been made in some period of time;
        • The robots fail to touch each other for some period of time;
        • The robots are hopelessly entangled or otherwise deadlocked;
        • Both robots fail to start or both contestants signal stoppage;
        • At the referee’s discretion, the referee may choose to end a round and choose the round winner if:
          • Smoke, fire, damage, or any other violation has occurred;
          • No progress is likely to be made even if the round is restarted.
      8. Repairs, modifications, unpredicted interruptions
        • If a robot gets broken during a match, the referee will assign a repair within 5 minutes. The repairs will be supervised by the one referee, to avoid changing the robot modules with other unapproved ones;
        • If a robot can not be repaired within the range specified, the match is won by the opponent robot, but the broken team can continue repairs until the next match involved, in this case being supervised by a referee / member of the organizing committee;
        • Replace defective parts can be made and the batteries can be recharged during the competition, if necessary;
        • If there any modification made to the robot after inspection, the robot must pass again the inspection stage.
      9. End of Match
        • The first robot to win two rounds, wins the match.
        • A match may also end if a contestant or robot is disqualified or otherwise unable to compete.
        • The contestants leave the ring area to prepare their robots for any additional matches in the contest.


    The kill switch is used to cut the power of the robot motors. When the referee sends the stop command, the power to the motors has to be cut. The robot builder is responsible for adding such a kill switch on the robot, however the prebuilt module can supply the signal for activating the kill switch.

    The prebuilt module takes care of all the communication and it is very easy to implement. The robot only needs to wait for the start pin on the module to go high and then it should start. The module accepts supply voltage (VCC) 3.3 - 5V. The VCC GND Start has a standard of 2.54 mm pitch. The prebuilt module can be ordered from the organizer, having a surcharge, during the online registration.

    The figure below illustrates the modes of operation of the module. To be less sensitive to noise and disturbances, the module will save its current state into a non - volatile memory and if it resets, it will return to the last known state. This means that each match will end with the referee sending the stop command.
    If the LED on the module is “on” before the referee has sent the start command, it means that the module is in the “Started” state. Then, the stop command has to be sent and the robot needs to restart for the module to go back to the “Power ON” state. To be able to run multiple matches next to each other, each dohyo will have its own unique identifier. The prebuilt module can be re-programmed to listen to a new identifier. This is done by the referee, by sending a special programming command which updates this identifier.

    The module has an option of usage without the special remote control. On the back of the module there are two large pads- Home and GND. If one of them attaches an 1 Kohm resistance between the two pads, the module will accept signal from a standard TV remote control (the remote control that uses RC-5 coding and was developed by Philips, but there are many other companies that use the same protocol). Sony and Nec have their own protocol and the remote control will not work. The best way to test if the remote control works, is to test it with the module. Pressing the 1 button from the TV remote control will be START and 2 will be STOP.

    You can find detailed information about the usage of the start modules on:
    How to implement Kill switch circuit using a relay:
    How to implement Kill switch circuit using an optocoupler: