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Lego Sumo Bot Rules (updated 08/19/15)

Lego Sumo Bot Rules

Next Event:

Saturday, February 27, 2016 @ Bret Harte High Multipurpose Room, next to school theater.


Registration/calibration starts 9:00 AM. No entry fee.

Competition starts between 10:00-10:30 AM


Students will have access to Bret Harte laptop computer prior to competition for any needed programming changes for calibration of robots.

Students should strongly consider bringing their program(s) on flash/thumb drives, and are welcome to bring their own laptops.


Note: the 2015 Rules are the same as last year except robots cannot have tank treads or caterpillar tracks. Plus the referee shall balance starting times for robots not properly programmed with 5 second delay.


2015-16 Cybullfrogs Sumo Bot Competition

The Cybullfrogs Sumo Bot Competition will be conducted in accordance with the following guidelines:



Prior to competition, all robots must be checked in, measured, examined and photographed by

Cybullfrogs staff.


Robot teams of maximum four students for each robot shall sign in and complete registration forms.


Match Procedure

A match consists of a series of individual bouts between the two autonomous robots until one side

earns five or more bout points to win.


Each bout win is worth 3 points, each bout draw is worth 1 point, and each bout loss is worth 0



Note: after three straight draws, the side with more bout wins will be declared the match winner. If

neither side has a bout point advantage, the match will be declared a draw.


Prior to the start of each match, the contestants will shake hands with each other outside the playing field.


At the conclusion of the match, both contestants shall shake hands and thank each other for a fair

and competitive match after removing removing their robots.


Beginning of a Bout

At the referee's directive, one contestant from each team will enter the playing field and

simultaneously and place their robots behind their respective starting lines facing away from the line.

No part of the robot placed shall be placed in front of the starting line.


At the referee’s signal, the contestants will press the start buttons on her/his robot and exit the ring.


The robots are be programmed to begin action no earlier than five seconds after the contestant

presses the robot’s start button. The contestants must exit the playing field during this 5 second

period. Should robots have been programmed to not hesitate five seconds before action, then the referee shall take suitable actions to neutralize differences to balance the robots start, and the non-conforming robot should have its software modified for future battles.


At any time after the start of any bout, the robot can expand outside qualifying 9 by 9 inch



End of the Bout

The referee declares a bout winner:


  • when a robot ejects its opposing robot from the ring with a fair action. The robot is considered ejected the moment more than half of the of the robot touches beyond the edge of the ring. A robot with more than half on the ring and the edge of the ring is not considered ejected, and is still in play.
  • when the opponent’s robot goes out of ring on its own for any reason.
  • when the opponent's robot stops moving on the playing field for more than 10 seconds.
  • when an opponent's operator interferes with either robot during the match.

The referee declares a bout draw:

  • if neither robot moves or is pushed outside the ring within 3 minutes.

Restarting a Bout

A bout will be stopped and restarted under the following conditions:

  • the robots are locked together or entangled in such a way that no progressive action appears to be possible for both sides, i.e. they have no movement or have rotated in circles several times.
  • both robots exit the exterior of the ring at the same time.
  • parts of a robot fall off within the ring. At the referee's directive, the operator will be given 45 seconds to repair the robot. A second part loss by the same robot will result in a bout loss. (The referee may ignore this infraction if the offending side is at a positional disadvantage during the bout.)
  • any other conditions under which the referee judges that merits a stop and restart.

In case of a restart, maintenance of competing robots is prohibited except as directed by the referee.


If continual restarts occur, the referee may set both bots in more confrontative starting positions.


Robot Specifications


The following restrictions shall apply to the robot design:


The robot must:

  • be able to fit inside a square template with inside dimensions 9 by 9 inches prior to the start of a bout. There is no height limitation.
  • weigh no more than 32 ounces.
  • be made solely of components from Lego NXT/EV3 retail or educational kits with the only exceptions being shorter "NXT/EV3 cables" with the exception of tank treads or caterpillar tracks.
  • be autonomous. All actions must be totally pre-programmed. The use of any form of remote control (infrared, bluetooth, etc) is prohibited.

        The robot may:

  • use any motors and sensors (light, touch, ultrasonic, color, gyro, etc) included in Lego robotic kits.
  • use a maximum of one NXT/EV3/RCX “brick” for control and 3 motors for movement/actuation. There is no restriction on operating system or programming environment.

The robot will not:

  • comprise of any third-party or non-Lego parts.
  • include any attachments or exhibit any behavior whose purpose is to damage the opponent's robot.
  • present a hazard to event competitors, officials, or spectators. Such robots deemed by the judges to be hazardous will not be allowed to compete.
  • include any parts that might damage or deface the sumo ring.
  • include any part that fixes the robot to the ring surface and prevents it from moving (such as suckers, glue, etc).


Sumo Ring Specifications

The sumo ring is defined as the white circular area within a radius of 18 inches. The sumo ring

includes a black border line of width 1.25 inches. Within the ring will be two symmetrically placed red

starting lines of length 4 inches.


Number of Matches

The format (round robin, double elimination, etc.) and number of matches will depend on the number

of entrants. Efforts will be made to maximize competition.