Robots must be constructed of ONLY Lego bricks. The computer must be either an RCX or an NXT. Each robot is limited to one computing device, three motors, and four sensors of any type. Each person may build up to two robots.

Robots must be programmed for autonomous operation, and no human interference is allowed after a match is started.

Robots must be less than a 18" long, although height is unlimited.

Robots may not purposefully injure the sumo ring. Robots may not spray anything onto the ring. Robots may not interfere with other robots programs. You are allowed to try to damage the other robot.

The Ring is several feet in diameter with a black outside perimeter line and white inside.

Each competition uses double-elimination rules.  (You need to loose two matches before you are eliminated).

Each match is between two robots.  A match lasts for either three bouts or three minutes, whichever comes first.

To start a bout, two robots are placed back to back in the center of the ring. Each robot must have a five second delay on it after the run button is hit. No motors are allowed to move during this five seconds.  No remote starts are allowed.  The robots must move forward 8 inches before turning.

A bout ends when one robot is no longer able to move under its own power for at least 5 seconds, a robot touches the outside of a ring for more than five seconds, the robots are deadlocked for more than thirty seconds, both builders agree on a draw, or when the match time runs out.  A robot is declared unable to move under its own power when it cannot cause its position within the arena to change by more than 5 mm through its own efforts.

(Typical sumo competition rules are that a robot is out as soon as it touches the floor outside the ring.  However, these bouts are usually held on wooden arenas that are a half inch or so off the floor, so that bots can often briefly leave the ring without tipping enough to touch the floor.  Our 5 second rule is to accomodate the fact that our arenas are printed on paper, so any brief excursion from the ring results in touching the floor.)

Each bout is scored by two points for a win, one for a draw, and zero for a loss.

The match is over when three bouts have ended or the three minutes are up. If the robots have the same number of points, a sudden death round is played.

The robot with the most points at the end of a match wins the match.  If the losing bot has lost one other round, it is then out of the competition.

A maximum of one minute of repairs can be made between bouts. You are not allowed to reprogram during the competition. Longer repairs can be made after the end of a match.