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Tug of War Rules

Tug of War Rules (UPDATED 10/31/18)

2018 Cybullfrogs Tug of War Competition

The Cybullfrogs Tug of War 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

Prior to the start of each match, the contestant(s) will shake hands with each other outside the playing field.

At the conclusion of the match, contestant(s) shall shake hands and thank each other for a fair and competitive match after removing their robots.

  • Both robots will have opposite ends of a string of approximate length 12 inches attached at the same vertical height.
  • The robots will be placed facing opposite directions with the middle of the string placed on the marked centreline labled on the floor/ground.
  • At the command by the official, both contestants will start their robots. Robots must be pre-programmed to move forward with no time delay.
  • If any part of a robot crosses the centerline, or any part comes off a robot, that robot loses that round.
  • A robot must win 2 out of 3 bouts to win the match.
  • After 1 minute, if neither robot has crossed the centerline, the bout is to be considered a draw.
  • In the case of a draw, where neither robot is successful in pulling the other across the centerline, the winner is determined by holding a tie-breaking bout in which the winner is determined by measuring the distance of each robot from the centerline at the end of the time limit. The robot closest to the line loses.

Robot Specifications

The following restrictions shall apply to the robot design for the Tug-of-War competition.

The robot must:

  • be able to fit its base 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 including tank treads or caterpillar tracks.  The shorter NXT/EV3 cables may be used.
  • 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 “brick” for control and 4 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 part that fixes the robot to the floor and prevents it from moving (such as suckers, glue, etc).

Some online resources include:


Inferno Lab