The rules are based on the official Japanese rules and are based on fair play, and good will. The robot must be active, no cinder blocks allowed.

The robot must initially fit into a 30cm x 24cm cm square, but can expand beyond this limit after it has been activated. The robot must remain still and be activated by the sound sensor before any motion occurs, to allow the operator time to move away. The robot must not be designed to damage the ring, or the other robots. Battery power only. The robots must be totally autonomous (brains on board) meaning, no remote control or human intervention of any kind, and no tethered, IR, or RF connection to a host computer. The sumo class is as follows:



Lego Sumo / 3 Kg Limited Class

30cm x 24cm size limit, no height limit. (not official size)
3 Kg Max (1 Kg = 2.2lbs) weight limit.
Will use a 150 cm ring
Parts are limited to those Lego pieces in your NXT kit only.

 

All you have to do is make sure your robot can push the opponent out of the ring... The official rules as they pertain to judging and officiating can be viewed below.

To inspire you I have embed a video: Enjoy.

Specifications For Robot
  1. A robot must be in such a size that it can be contained in a box of 30cm x 24cm x free(height). (Free shape)
  2. Robot's Weight must be under 3 kg (Heavyweight class) including all the parts/attachments.
  3. Models of robots must be autonomous. - No assistance
  4. Stand-alone robot must start moving autonomously, without operator's manual operation. Robots must use a sound sensor that triggers the bot to start after hearing a sound louder than 90db.
  5. Any senors can be used to control stand-alone robots.
  6. Give a Shikona (Name) to your robot.
Specifications of the Ring Ring for Robot Sumo Diameter - 1m50cm Material - White Ring - Yellow Shikiri line - Black Tawara Ring - Black
 

Software Design Advice

1. Organization. Plan the layout of your program.

2. Navigation. You must solve two issues:

a. Path Planning: You may want to position your robot as close to the center as possible. Ensure your robot does not drive outside of the ring by itself.

b. Opponent Identification: You must locate your opponent's position so that you can either push him out of the ring or topple him.

Rules for Sumo Matches

Section 1. Definition of the Sumo Match

Article 1. (Definition) The match shall be fought by the two robots according to these Rules for Sumo matches (hereafter called "these Rules"), with each team's robot made by each team (a standalone model) competing to get the effective points (hereafter called Yuhkoh), within the perimeter of the defined Sumo Ring. The judges will decide which team wins.

Section 2. Requirements for Ring Area

Article 2. (Definition of Ring Area) The Sumo Ring consists of the Inner Area inside the Tawara Ring and the space outside the Ring. Anywhere outside the Tawara Ring is called Outer Area.

Article 3. (Sumo Ring)

  1. The Ring shall be in circular shape with its diameter 154cm (including the outside of the line that divides the inside of the Ring from its outside). The Tawara Ring shall be 4cm wide and constructed of black tape.
  2. Shikiri lines (where robots stand at the beginning of the match) are the two parallel lines with 20cm distance between the lines, drawn in the center of the Ring. The Shikiri lines yellow tape, 2cm wide and 20cm long.

Section 3. Requirements for Robots

Article 5. (Specifications)

  1. A robot must be in such a size that it can be put in a box of 30cm x 24cm. A robot can be of any height. A robot must not be in such a design that its body will be physically separated into pieces when a match starts. The robot with such a design shall lose the match. The design to stretch a robot's body or its parts shall be allowed. Small pieces falling off from a robot's body during the match shall not cause the loss of match (unless they interfere with the operation of the competitors robot).
  2. The weight of a robot must be no more than 3Kg or 6.6 pounds including the attachments and parts
  3. Stand-alone models must be so designed that a robot starts operating after the start sound has been detected.

Article 6. (Don'ts in manufacturing a robot)

  1. Do not use devices that throw things at your opponent.
  2. Do not design your robot to intentionally damage/break another robot.
  3. Hammer bots are not allowed.
  4. All sensors must be protected from impact (except for touch sensors)

Section 4. How to Carry Sumo Matches

Article 7. (How to Carry Sumo Matches)

  1. One match shall consist of 3 games.
  2. The team who received two "Yuhkoh" points first, within the time limit, shall win the match. When the time limit is reached, and one of the teams has received only one Yuhkoh point, the team with one Yuhkoh point shall win.
  3. When the match is not won by either team within the time limit, the extended match shall be fought during which the team who receives the first Yuhkoh point shall win. However, the winner/loser of the match may be decided by judges or by means of lots, or there can be a rematch.
  4. One Yuhkoh point shall be given to the winner when the judges' decision was called for or lots were employed.

Section 5. Start, Stop, Resume, End a Match

Article 8. (Start) With the chief judge's instructions, the two teams bow in the Outer Ring and go into the Ring Area, place a robot on or behind the Shikiri line or the imaginary extended Shikiri line. (A robot or a part of a robot may not be placed beyond the Shikiri line toward the opponent.). A match starts with the following rules:

  1. For stand-alone robots, be ready to press a start switch. Press the switch when the chief judge announces the start of the match. The robots must wait until they hear a sound greater than 85 dB created by the chief judge before the robot starts operating, before which players must clear out of the Ring Area.

Article 9. (Stop, Resume) The match stops and resumes when a judge announces so.

Article 10. (End) The match ends when the chief judge announces so. The two teams bring the robots out of the Ring Area, and bow.

Section 6. Time of Match

Article 11 (Time of Match) One Match will be fought for 3 minutes, starting and ending by the chief judge's announcements. For stand-alone robots, the clock shall start ticking immediately  after the start signaled by the head judge.

Article 12. An extended match shall be for 3 minutes.

Article 13. The following are not included in the time of the Match:

  1. The time elapsed after the chief judge announces Yuhkoh and before the match resumes. 30 seconds shall be the standard before the match resumes.
  2. The time elapsed after a judge announces to stop the match and before the match resumes.

Section 7. Yuhkoh

Article 14. (Yuhkoh) One Yuhkoh point shall be given when:

  1. You have legally forced the body of your opponent's robot to touch the space outside the Ring.
  2. A Yuhkoh point is also given in the following cases:
    1. Your opponent's robot has touched the space outside the Ring, on its own.
    2. Either of the above takes place at the same time that the End of the Match is announced.
    3. When judges' decision is called for to decide the winner, the following points will be taken into considerations:
      1. Technical merits in movement and operation of a robot
      2. Penalty points during the match
      3. Attitude of the players during the match
    4. The match shall be stopped and a rematch shall start when:
      1. Both robots are in clinch and stop movements for 30 seconds, or move in the same orbit for 30 seconds.
        1. Both robots move or stop for 30 seconds without touching each other.
        2. If one robot stops it's movement for 30 seconds, or has been rendered unable to fight, he shall be considered not having the will to fight, and the opponent shall receive a Yuhkoh.
        3. Both robots, at the same instance, touch the space outside the Ring.

Section 8. Violations

Article 15. (Violations) If the players perform the deeds as described in Articles 6, 16, and 17, the players shall be declared as violating the rules.

Article 16. The player utters insulting words to the opponent or to the judges.

Article 17. A player:

  1. Enters into the Ring during the match, except when the player does so to bring the robot out of the Ring upon the chief judge's announcement of Yuhkoh or stopping the match. To enter into the Ring means:
    1. A part of the player's body is in the Ring, or
    2. A player puts any mechanical kits into the Ring to support his/her body.
  2. Performs the following deeds:
    1. Demand to stop the match without appropriate reasons.
    2. Take more than 30 seconds before resuming the match.
    3. Start operating the robot before the chief judge announces the start of the match.
    4. Do or say that which should disgrace the fairness of the match.

Section 9. Penalties

Article 18. (Penalties) Those who violate the rules with the deeds described in Articles 6 and 16 shall lose the match. The judge shall give two Yuhkoh points to the opponent and order the violator to clear out. The violator is not honored with any rights.

Article 19. Each occasion of the violations described in Article 17 shall be accumulated. Two of these violations shall give one Yuhkoh to the opponent.

Article 20. The violations described in Article 17 shall be accumulated throughout one match.

 

Section 11. Declaring Objections

Article 25. (Declaring Objections) No objections shall be declared against the judges' decisions.

Article 26. The lead player can declare objections to the Committee, before the match is over, if there are any doubts in exercising these rules.

Section 12. Requirements for Identifications for Robots

Article 27. (Identifications for Robots) Identifications for robots shall be of Green color for the East players, Yellow for the West. Two seals for identification (2cm in diameter) must be adhered to a body of a robot. (You will put a piece of coloured tape on your robot).

Section 13. Miscellaneous

Article 28. (Flexibility of Rules) As long as the concept and fundamentals of the rules are observed, the rules shall be so flexible that they will be able to encompass the changes in the number of players and of the contents of matches.

Article 29. (Change in Rules) Any changes to or obsolescence of these rules shall be decided head judge.

Last modified: Monday, 12 January 2026, 4:45 PM