Mega Sumo — Official Rules

1. Definition of the Sumo Match

1.1 Definition

A match is fought between two teams, each with one or more members. Only two team members may approach the ring: the operator and the assistant. Others must watch from the audience. Under these rules, each team competes on a sumo ring with a self-built robot meeting Section 2. The match starts on the judge’s command and continues until a contestant earns two points. The judge determines the winner. After the match, the operator and assistant return to their assigned room and await the next game.

2. Requirements for Robots

2.1 General Specifications

• Any design is allowed unless limited by Section 2.2.
• Robot must fit within a 200 × 200 mm square at start.
• Total mass at start must be under 3000 g.
• The robot may expand after the match begins, but may not separate into multiple parts and must remain a single centralized robot. Feet must not expand during the match. Components with a total mass < 5 g falling off do not cause a loss.
• Robots are fully autonomous. All control must be onboard; no external systems may influence operation.
• A visible competition number (provided by organizers) must be affixed to the outer shell.
• The minimum allowed size for robots in this category is 150 × 150 mm.
• Robots that fall within the dimensions of a lower category (e.g., Mini, Micro, or Nano) are not eligible to compete in the Mega Sumo 3 kg Auto category.

2.2 Restrictions

• Robot must be equipped with an IR kill/start interface operable by the judge. On kill, motor power must shut down. Teams may implement their own receiver or use an organizer module. The IR start module must function during inspection and all matches; non-function or absence results in disqualification.
• Jamming devices (e.g., IR LED flooders) are prohibited.
• No parts may damage the ring or opponent. Normal pushing is allowed; intentional damage is not.
• No liquids, powders, gases, or other substances may be deployed.
• No flames or projectile devices.
• Sticky traction is prohibited. Any contact surface must not pick up and hold an A4 sheet (80 g/m²) for more than 2 s.

3. Sumo Ring

3.1 Interior

The  interior of the ring is the playing surface including the border line. Everything outside is the exterior of the ring.

3.2 Specifications

• Ring: circular, steel 5 mm (or equivalent rigid surface) painted black, diameter 1540 mm.
• Border line: white circular ring, width 50 mm.
• Platform height: 50 mm nominal.
• Dimensional tolerance: ±5%.
• Starting lines: 200 × 20 mm.

3.3 Exterior

A suitable safety area surrounds the ring (color/material optional) and will be referred to as the “ring area”.

3.4 Match format on the ring

• One match: best of 3 rounds within 3 minutes total unless extended by judges.
• First team to earn two points wins the match.
• If time expires with one team holding one point , that team wins. Otherwise, an extended match may be fought; first point wins. Judges may also decide by lots or order a rematch.
• If robots get stuck, see 6.1.
• If a robot fails to start, one restart is allowed. If it fails again, the point is awarded to the opponent.
• If a hand-held repeater is used to point at the start sensor, no restart will be given for failure to start; responsibility lies with the team.

3.5 Course of the Competition

Important: One person may be operator for a maximum of 2 robots for the entire contest.

• Robots are split into groups. Competition proceeds via groups → quarterfinals → semifinals → finals. Group matches are best-of-3; finals may be best-of-5. Three referees supervise (one principal, two assistants). Ref decisions are unanimous and final; disputing may lead to disqualification.
• Robots from the same team that meet in playoffs must play; no advancement by arrangement is permitted.
• Group order is randomized after the opening; brackets/schedule are posted on the website.
• If participants are too few for groups, a pyramidal (knockout) system is used; positions are random.
• No breaks are allowed during a match. Between matches, changes, repairs, and reprogramming are allowed.
• Teams remain in their assigned room and only leave when called to the waiting area near the competition area.
• Homologation (tech check) is performed for robots about to start; they remain in the waiting area.
• Follow the posted schedule. Do not be late. If called and you do not arrive within 5 minutes, the robot is disqualified.
• Each team has one operator and one assistant allowed in the waiting/game area.
•  Missing gear may yield a point  for the opponent or disqualification.
• Up to 1 minute between rounds for cleaning and configuration (without touching the placed robot).
• Once placed in the ring, robots may not be touched until instructed by the judge after the fight ends.

3.6 Homologation (Technical Inspection)

At event start

• Verify competition number on the robot shell.
• Take a photo with the number visible.
• Dimension check with a bottomless 203 × 203 mm frame.
• Weighing: ≤ 3005 g.
• Verify IR start/kill operation.

Before every match

• Dimension check with 203 × 203 mm frame.
• Weighing: ≤ 3005 g.
• Verify visible number and protective gear.

After homologation, the first queued teams remain near the arena; others return to their room.

4. Start, Stop, Resume, End

4.1 Robot placing

• On the judge’s instruction, operators place robots simultaneously on the ring.
• All robot parts must be behind the starting lines. No part may cross toward the opponent.
• Placement must be within the vertical projection of the starting lines. Incorrect placement → re-positioning.
• After placement, operators retreat to the marked safe area.

4.2 Start

The judge starts each round by sending an IR start signal. Upon receiving it, robots start immediately with no delay. Start occurs only after operator/assistant are in the safe area. Leaving the safe area without approval may cost a point or cause disqualification.

4.3 Stop / Resume

The judge alone stops and resumes the match and announces when robots may be placed, when to retreat, and when to collect robots.

4.4 End

The match ends when the judge declares so. Teams recover robots. After recovery, the decision is final; no objections are accepted.

5. Time of Match

• Duration: up to 3 minutes per match.
• Extension: if called by the judge, up to 3 minutes.

6. Scoring

One point shall be given when:

• A team legally throws the opponent robot outside the ring.
• The opposing robot touches outside on its own.
• The opposing robot leaves the ring surface completely, even if the attacker later exits.
• The opposing robot is damaged and cannot continue and this is announced by its representative.
• If both exit together, the first one robot that leaves the ring loses the round.

Judges’ decision factors (if required)

• Technical merit in movement and operation.
• Penalty points incurred.
• Players’ attitude and fair play.

6.1 Stoppages & Rematches

• If one robot does not start: one restart. If it still fails, the point goes to the opponent.
• If robots are entangled/orbiting with no progress for ~10 s: one restart. If repeated, the robot that moves more and shows will to fight wins.
• If a fast robot is stuck in a slow robot > 5 s: one restart. If repeated, the faster attacking robot wins the round.
• If a robot has 1 point and the next round has no winner, only 2 rematches are allowed. If still no winner, the robot with 1 point wins the match.
• If both move without progress or both stop simultaneously for 5 s and are not touching, the first to stop is deemed lacking will to fight and the opponent receives a point  (even if it later stops). Judge may extend up to 30 s to assess progress.
• If both touch outside at about the same time and first contact cannot be determined: rematch.

6.2 Repairs & interruptions

• No repairs during a match.
• No battery change/charge during a match.
• No blade change during a match.
• No reprogramming during a match (pre-fight tactic selection is allowed).
• If the blade detaches during a round, it may not be reattached; continue without it.
• A. The robot must start and finish the entire match without modification (except tactic selection) and may not leave the competition area.
• B. Max 1 minute between rounds to clean and configure.
• C. Battery/service/part replacement allowed only after the match and before the next match.
• D. If a robot breaks during a match and cannot continue, the opponent wins; no repair allowed.

7. Violations

7.1 General

Performing any deeds described in Sections 2.2, 7.2, or 7.3 constitutes a violation.

7.2 Insults

Insulting opponents or judges in speech, via robot audio, or written on the robot, or any insulting action, is a violation.

7.3 Protective Gear & Safe Area

• Operator/assistant not wearing mandatory gear during a match.
• Operator/assistant failing to retreat to the safe area or disobeying referee instructions.
• Missing or non-functional start/stop module → disqualification.

7.4 Minor Violations (warnings)

• Entering the ring during a match (except after a point and instructed by the referee). “Entering” means any body part in the ring or inserting tools to support the body.
• Asking to stop the match without valid reason.
• Taking > 60 s to resume without judge-granted extension.
• Actions contrary to fair play.
• Leaving the waiting area without informing officials/referee.

If a team accumulates 2 warnings, one point is awarded to the opponent, or the team may be disqualified depending on severity.

8. Penalties

• Violations under 2.2, 7.2, 7.3 → match loss; opponent receives two points; violator must leave the area.
• Minor violations under 7.4 accumulate; two such violations → one point to the opponent.
• Accumulation applies within a single match.

9. Objections

• No objections against judges’ decisions.
• Rule-application doubts may be raised by the operator to the Committee before the match ends. If no Committee is present, raise to the judge before match end.

10. Flexibility of Rules

As long as the core concepts are observed, organizers may modify or abolish rules provided changes are published prior to the event and applied consistently.

11. Liability

• Teams are responsible for their own safety and that of their robots and are liable for any accidents they cause.
• The Relativity Robotics Challenge organization and staff are not responsible or liable for incidents/accidents caused by teams or their equipment.

Addendum 1 

• Protective Eyewear: Designed to provide lateral and frontal protection against minor mechanical impacts. Features translucent lenses and allows use over corrective eyewear. Compliant with safety standards for eye protection against low-energy hazards.

  Gloves: Engineered to protect hands from mechanical hazards, thermal risks (heat and cold), flame exposure, moisture, and contact with toxic substances. Suitable for use in environments with multiple physical and chemical hazards.

  Exclusions from Personal Protective Equipment (PPE): Sunglasses, medical-grade latex gloves, standard textile gloves, and ski gloves are not considered effective protective equipment under applicable safety regulations.

Addendum 2 

• Robot Identification Numbers – Unique numbers assigned to each robot.

• Participation Certificates – Diplomas awarded to all participating teams.

• Team Member Badges – Identification badges for all team members.

• Team Room and Competition Area Information – Details regarding assigned team rooms and a map of the competition areas.

• Promotional Materials – Flyers, brochures, and other informational or marketing items.

• Group Formation Guidelines – Instructions and criteria for forming teams or groups.

• Maps of Team Rooms and Competition Areas – Detailed layout maps to navigate team rooms and competition zones.

Addendum 3

Remote Start & Stop

Details about start modules can be found at: startmodule.com

The Start/Stop Module

• Powered by 5V or 3.3V. Four pins: VCC, GND, Start, Kill.
• Kill pin may be monitored to cut motor power on stop (recommended for safety).
• Green LED indicates start/stop reception or error state.
• On power-up the green LED must be OFF (ready). If ON, ask the referee to press Stop and power-cycle the robot.

Signal semantics

• Start pin: 0 on power-on; goes 1 on start; returns 0 on stop.
• Kill pin: 1 on power-on/start; goes 0 on stop (use to disable motor power path if implemented).

Pseudocode (template)

robot_ready = false
initial = digitalRead(START_PIN)
if initial == 1:
  # Error: should be 0 at power-on
  while True:
    pass  # lockout until power-cycle
else:
  robot_ready = True

# Wait for start
state = 0
while state == 0:
  state = digitalRead(START_PIN)

# Run until stop
if state == 1 and robot_ready:
  while digitalRead(START_PIN) == 1:
    # fight logic
    pass
  # On stop, halt safely and lock out
  while True:
    pass