Mini-Sumo Robot Competition Rules


  • Encourage on-going interest in building robots with an annual showcase event.
  • Encourage design of autonomous robots
  • Encourage participation of all age groups in design competitions.
  • Allow maximum number of entrants (from inside and outside of the club).
  • Generate excitement from participants and audience during the competition.
  • Have Fun!

Note: Rules Summary is intended as a brief overview. Refer to the Full Specifications and Rules contained later in the document.

Mini-Sumo Match: Two robots compete one-on-one in a best two of three rounds match. The winner either pushes the opponent out of the ring or the opponent leaves the ring on its own. Each round has a 3-minute time limit with a mandatory five-second start delay.

Robot Specification: Robot must weight under 500 gm and not exceed 10 cm x 10 cm. In size. There is no height restriction. The robots must be autonomous. Radio Control is not allowed.

Competition Ring: Robots compete on a 77 cm diameter ring with flat black surface and a 2.5cm white rim.

Qualification: All competing robots must be able to push a wood block, 250 grams in weight, off the ring 2 out of 3 attempts. Qualifications will be performed at the contest prior to competition with the oversight of the Judge (Gioji) or an assigned witness. Robots may be quarantined after qualification until the scheduled competition.

Contest Format: Robots will compete in a series of one-on-one elimination matches until the top robot is the winner. Robots will be assigned to the first round of competitions based on a random draw prior to the contest. Some robots may be awarded a BUY during the elimination as a part of the assignment process. Each match consists of three rounds.

Disallowed: Jamming devices; parts that could inflict damage to the Ring or to the other robot; devices that can store and throw objects, liquid, powder, or air, at the opponent; flammable devices; and devices that adhere a robot to the Ring are not allowed.

Conduct: Sumo wresting is an honorable competition. The two teams bow in the Outer Ring at the beginning and end of each round. Actions that disgrace the fairness or honor of the match may be penalized at the discretion of the contest Judge (Gioji).

ELIGIBILITY: There are no requirements. We encourage all hobby robot builders to enter. All entries will be judged according to the rules of the contest. Groups or teams are allowed to enter as a single entry.

Video Tape: Makerspace Forsyth reserves the right to Video Tape and offer for sale any portion or all of the contest or program.

REGISTRATION: For competitions will appear on the regular club meeting notification emails when they come up.



Specifications For Robot

  1. A robot must be in such a size that it can be contained in a square tube of 10 cm (width) x 10 cm (depth) x any (height).  The robot can be any shape within this tube.
  2. Robot’s Weight must be under 500 gm including all the parts and attachments.
  3. The robots must be autonomous. Radio Control is not allowed.
  4. The robot must start moving, without the operator’s manual operation, 5 seconds after the operator pushes the start button when Gyoji announces the start of the match.
  5. Any mechanism can be used to control autonomous robots.
  6. Give a Shikona (Name, or number) to your robot, for registration purposes.  Display this name or number on your robot to allow spectators and officials to identify your robot.

Qualification and safety

  1. All competing robots must be able to push a wood block, 250 grams in weight, off the ring 2 out of 3 attempts.
  2. A safety inspection also must be passed, which involves evaluation for sharp edges and wheel treads that can catch a finger, etc. Officials have final say in regards to safety.

Specifications of the Ring

Ring for Robot Sumo

  • Diameter  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 77 cm
  • Material  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  Painted surface
  • Color
    • Inside the ring  .  .  .  .  .  .  .  .  .  .  . Flat Black
    • Shikiri line  .  .  .  .  .  .  .  .  .  .  .  .  .  Brown or grey, no more than 20% reflectivity of white for IR and visible light
    • Tawara  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  White
  • Illumination on the Ring surface  .  .  .  .  Under 1,000 lux

Rules for Sumo Matches

Section 1. Definition of the Sumo Match Article 1. (Definition)  The match shall be fought by two teams (At the event, one team consists of one robot with two team members, one of which is a leader.  Other team members must watch from the audience), according to these Rules for Sumo matches (hereafter called “these Rules”), with each team’s robot made by each team competing to get the effective points (hereafter called Yuhkoh), within the perimeter of the defined Sumo Ring.  The judges will decide which team wins.  A single person can also compete with a Robot Sumo, with the same rules that apply to teams.

Section 2. Requirements for Ring Area

Article 2.  (Definition of Ring Area)  The Ring Area means the Sumo Ring and the space outside the Ring.  Anywhere outside this Ring Area is called Outer Area.

Article 3. (Sumo Ring)

  1. The Ring shall be in circular shape with its height being 2.5 cm and its diameter 77 cm (including the outside of the line that divides the inside of the Ring from its outside).
  2. Shikiri lines (where robots stand at the beginning of the match) are the two parallel lines with 10 cm distance between the lines, drawn in the center of the Ring.  The Shikiri lines are 1 cm wide and 10 cm long They are painted brown or grey and shall have less than 20% of the reflectivity of the white outer ring.
  3. The Ring shall be marked by a white circular line of 2.5 cm thickness.  The Ring is within the outside of this circular line.

Article 4. (Space)  There should be the space of more than 50 cm wide outside the outer side of the Ring.  This space can be of any color except white, and can be of any materials or shape, as long as the basic concept of these rules are observed.  This area, with the ring in the middle, is to be called the: “Ring Area”.  If there are markings or part of the ring platform outside these dimensions, this area will also be considered in the Ring Area.

Section 3. Requirements for Robots

Article 5. (Specifications)

  1. A robot must be in such a size that it can be put in a square tube of 10 cm wide and 10 cm deep.  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, but must remain a single centralized robot.  Screws or nuts or other robot parts, with a mass of less than 5 grams total,  falling off from a robot’s body shall not cause the loss of match.
  2. The mass of a robot must be under 500 grams including the attachments and parts.
  3. Any autonomous control and sensor mechanisms can be employed.
  4. Robots must be so designed that they start operating a minimum of  five seconds after a start switch is pressed (or any method that invokes the operation of a robot).
  5. Microcomputers in a robot can be of any manufacturer and any memory sizes can be chosen.

Article 6. (Don’ts in manufacturing a robot) Jamming devices, such as an IR LED intended to saturate the opponent’s IR sensor, are not allowed. (Note: Passive materials used for stealth, deception or camouflage which remain attached to the robot are not considered jamming devices.)  Do not use parts that could break or damage the Ring.  Do not use parts that are intended to damage the opponent’s robot or it’s operator.  Normal pushes and bangs are not considered intent to damage.

  1. Do not put into a robot’s body devices that can store liquid, powder, or air, which are intended to be thrown at the opponent.
  2. Do not use any inflaming devices.
  3. Do not use devices that throw things at your opponent.
  4. Do not stick a robot down onto the Ring, using sucking devices or glue, or use any type of sticky tires (such as double sticky foam tape) or any  device to assist in adding more down force (such as a vacuum device).

Section 4. How to Carry Sumo Matches Article 7. (How to Carry Sumo Matches)

  1. One match shall consist of 3 rounds, within a total time of 3 minutes, unless extended by the Judges.
  2. The team who wins two rounds or receives two “Yuhkoh” points first, within the time limit, shall win the match.  A team receives a “Yuhkoh” point when they win a round.  If the time limit is reached before one team can get two “Yuhkoh” points, and one of the teams has received  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 (Gioji’s) instructions, the two teams bow in the Outer Ring (For example, stand facing each other, outside the ring platform or “ring area”, with ring between),  go up to the Ring,  and 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 front edge of the Shikiri line toward the opponent.).  A match starts with the following rules: Press the switch when the chief judge announces the start of the round.  After 5 seconds, the robot is allowed to start 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 (Gioji) 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 a total of 3 minutes, starting and ending by the chief judge’s announcements.  The clock shall start ticking 5 seconds after the start is announced.

Article 12.  An extended match shall be for 3 minutes, if called by the Judge.

Article 13.  The following are not included in the time of the Match: The time elapsed after the chief judge announces Yuhkoh and before the match resumes.  30 seconds shall be the standard before the match resumes.

  1. 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: You have legally forced the body of your opponent’s robot to touch the space outside the Ring, which includes the side of the ring its self.

  1. 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.
  2. When a robot has fallen on the Ring or in similar conditions, Yuhkoh will not be counted and the match continues.
  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 5 seconds, or move in the same orbit for 5 seconds, with no progress being made.  If it is not clear if progress is being made or not, the Judge can extend the time limit for a clinch or orbiting robots up to 30 seconds.
    2. Both robots move, without making progress,  or stop (at the exact same time) and stay stopped  for 5 seconds without touching each other.  However, if one robot stops it’s movement first, after 5 seconds, he shall be considered not having the will to fight, and the opponent shall receive a Yuhkoh, even if the opponent also stops.  If both robots are moving and it isn’t clear if progress is being made or not, the Judge can extend the time limit up to 30 seconds.
    3. If both robots touch the outside of the ring at about the same time, and it can not be determined which touched first, a rematch is called.

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 or puts voice devices in a robot to utter insulting words or writes insulting words on the body of a robot, or any insulting action.

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, unless the Judge announces a time extension.
    3. Start operating the robot within 5 seconds after 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 10. Injuries and Accidents during the Match

Article 21. (Request to stop the Match)  A player can request to stop the game when he/she is injured or his/her robot had an accident and the game cannot continue.

Article 22. (Unable to continue the Match)  When the game cannot continue due to player’s injury or robot’s accident, the player who is the cause of such injury or accident loses the match.  When it is not clear which team is such a cause, the player who cannot continue the game, or who requests to stop the game, shall be declared as the loser.

Article 23. (Time required to handle injury/accident)  Whether the game should continue in case of injury or accident shall be decided by the judges and the Committee members.  The decision process shall take no longer than five minutes.

Article 24. (Yuhkoh given to the player who cannot continue)  The winner decided based on Article 22 shall gain two Yuhkoh points.  The loser who already gained one Yuhkoh point is recorded as such.  When the situation under Article 22 takes place during an extended match, the winner shall gain one Yuhkoh point.

Section 11. Declaring Objections

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

Article 26.  The lead person of a team  can present objections to the Committee, before the match is over, if there are any doubts in exercising these rules.  If there is no Committee member present, the objection can be presented to the Judge, before the match is over.

Section 12. Requirements for Identifications for Robots

Article 27.  (Identifications for Robots)  Some type of name or number, to identify the robot (as registered in the contest) must be easily readable on the robot’s body, while the robot is in competition..

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 by the General Committee Meeting based on the Sumo Match Committee Rules.

Article 30.  (Posting of Rules) A copy of these rules will be present at all competitions and will be available for perusal by any judge, official, or contestant before any competition.