Sumo Rules
Spend a happy Sunday afternoon at the San Francisco Exploratorium watching tiny Sumo robots compete by pushing each other out of a 5 foot diameter ring using brute strength, brilliant programming, sensors, etc.

Official FUJI All Japan Rules for Sumo Matches

The Rules have been modified for SFRSA contests to accommodate the local conditions of the SFRSA contests. These changes are noted in red italics in the relevant rules.

Section 1. Definition of the Sumo Match

Article 1. The match shall be fought by the two teams (one team consisting of one robot with two players, one of which is a leader), according to these Rules for Sumo matches (hereafter called "these Rules"), with each team's robot made by each team (either a radio-controlled model or a stand-alone 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. (SFRSA Note: There are no RC contests held in SFRSA SUMO)

Section 2. Requirements for Ring Area

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

Article 3.

1. The Ring shall be in circular shape with its height being 5cm and its diameter 154cm (including the outside of the line that divides the inside of the Ring from its outside.) The Ring shall be of black hard rubber (made by Toyo Linoleum: long vinyl sheet NC HR289) adhered on top of aluminum plate.

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 fines are painted in brown. 2cm wide and 20cm long.

3. The Ring shall be marked by a white circular line of 5cm thickness. The Ring is within the outside of this circular line.

Article 4. There should be the space of more than 100cm wide outside the outer side of the Ring. This space can be of any colour except white, and can be of any material or shape, as long as the basic concept of these rules are observed.

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 20cm wide and 20 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. Screws or nuts (each within one cubic centimeter) falling off from a robot's body shall not cause loss of a match.

2. The weight of a robot must be under 3000 grams including the attachments and parts, but excluding the weight of a proportional system (hereafter called "Prop") for radio controlled models.

3. The radio frequencies for radio-controlled robots must be either 27MHz (1-6 bands) or 40MHz (61, 63, 65,69 bands). 40 MHz (71-83 bands) cannot be used.
(SFRSA Sumo is autonomous robots only - no remote control)

4. The Prop must be one of Fubata's, JR's, Sanwa's or Kondo Kagaku's. Only one Prop can be used for one robot.

5. For stand-alone robots, any control mechanisms can be employed.

6. Stand-alone models must be so designed that a robot starts operating five seconds after a start switch (or any switch that invokes the operation of a robot) is pressed.

7. Microcomputers in a robot can be of any manufacture and any memory size can be chosen.

"Don'ts" in manufacturing a robot

Article 6.

1. Do not disturb your opponent's radio-control by putting into a robot's body such devises as a jamming device.

2. Do not use parts that could break or damage the Ring.

3. Do not put into a robot's body devices that can store liquid, powder, or air and throw it to the opponent.

4. Do not use any inflaming devices.

5. Do not use devices that throw things at your opponent.

6. Do not stick a robot down into the Ring, using sucking devices or glue.

Section 4. How to Carry Sumo Matches

Article 7.

(SFRSA Rules: The contest consists of a series of round-robin matches in which every robot is matched against all other robots. One point is assigned to the winner, zero to the loser. One-half point is assigned to each contestant in a tie. After all matches, the best score wins. In the event of a tie, an elimination round is played among the tied robots until one winner results)

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 the 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. 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 fine or the imaginary extended Shikiri line. (A robot or a part of a robot may
not be placed beyond the Shikiri fine toward the opponent.) A match starts with the following rules:

1. For radio-controlled robots, starting operating a Prop when the chief judge announces the start of a match.

2. For stand-alone robots, be ready to press a start switch. Press the switch when the chief judge announces the start of a match. After 5 seconds, the robot starts operating, before which players must clear out of the Ring Area.

(Stop, Resume)

Article 9. The match stops and resumes when a judge announces so.


Article 10. 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

(Time of Match)

Article 11. 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 5 seconds after the start switch is pressed.

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 (Scoring)

Article 14. One Yuhkoh point shall be given when:

1. You have legally forced the body of your opponent's robot to touch the spare outside the Ring.

2. A Yuhkoh point is also given in the following cases:

(1) Your opponents robot has touched the space outside the Ring, on its own reasons.

(2) Either of the above takes place at the same time that the End of the Match is announced.

3. When a robot has fallen on the Ring or in similar conditions. Yuhkoh will not be counted and the match continues.

4. When judge's decision is called for to decide the winner, the following points will be taken into consideration:

(1) Technical merits in movement and operation of a robot.

(2) Penalty points during the match.

(3) Attitude of the players during the match.

5. The match shall be stopped and a rematch shall start when:

(1) Both robots are in clinch and stop movement for 30 seconds, or move in the same orbit for 30 seconds.

(2) Both robots move or stop for 30 seconds without touching each other. If one robot stops its movement for 30 seconds, 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. 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, put voice device in a robot, or write insulting words on the body of a robot, for the same effect.

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 the Ring means:

1 .

(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 (for stand-alone robots).

(4) Start operating the robot within 5 seconds after the chief judge announces the start of the match (for stand- alone robots).

(5) Do or say that which should disgrace the fairness of the match.

Section 9. Penalties

Article 18. 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 honoured 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

(Request to stop the match)

Article 21. 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.

(Unable to continue the match)

Article 22. 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 a loser.

(Time required to handle injury/accident)

Article 23. 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.

(Yuhkoh given to the player who cannot continue)

Article 24. 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. 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

(Identifications for Robots)

Article 27. Identifications for robots shall be of red colour for the East players, blue for the West. Two seals for identification (2cm in diameter) must be adhered to the body of a robot.
(Not applicable to SFRSA competitions)

Section 13. Miscellaneous

(Flexibility of Rules)

Article 28. 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.

(Change in Rules)

Article 29. Any change to or obsolescence of these rules shall be decided by the General Committee Meeting based on the Sumo Match Committee Rules.

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Copyright 1998 San Francisco Robotics Society of America
Last modified: September  17, 1998