Contents: GameGame Rules General Contest RulesRobot Construction

The public is cordially invited to:

The 2007 Rice LEGO Robot Contest

Sunday, December 2, 2007


McMurtry Auditorium, Duncan Hall


Past Games and Winners

The Year 2007 Game: Robo Basketball

Two robots compete to earn the most points within a 90 second game. The robots first have to get balls from dispensers at the end of the board, and then earn points by depositing them in one or more goals located on the game board. The various goals have different levels of difficulty and point values. They can earn bonus points by shooting balls through a hoop goal from the other side of the table. Good strategy, skillful ball handling, and especially reliability will be important.


  • Fame, Glory, and Bragging Rights.
  • The winning robot will be kept for display next year, so you do not have to disassemble it.
  • A modest gift for winning team members; some assembly may be required.
  • The contest is for motivation, for demonstration of your accomplishment, and, most of all, for fun. Your grade in the course does not depend on your robot's placement in the contest. Top

Game Board, Objects, & Rules

General Contest Rules

Robot Structure Rules


The Game Board & Rules


The game board is a 6 foot by 8 foot flat surface. The red stars represent starting lights embedded in the board; a robot starts at each location, just in front of its hoop goal. The ball dispensers (BD) are at the far end of the table. There are two additional goals for each robot, one at the edge of the board, one in the center. At each end of the board, on the center line, are four 3" high posts or bollards extending 12" out into the playing area. One half of the board is painted flat black and has white lines to aid navigation; the other half is painted flat white and has black lines. The lines, indicated in the drawing by dark dashed lines, are 3/4 inch wide. The board has 5 inch high walls at all four sides; the inner side of all the walls are painted flat white. The drawing of the board is reasonably to scale, but the official dimensions are those of the physical game board. Since the board is constructed in parts, there may be small surface and wall misalignments; these should be less than 1/8 inch.


  • The balls are Hasbro Ballzooka Nerf Ballistic Balls, approximately 1.73 inches in diameter, with a slightly fuzzy, flat yellow surface. The balls are light weight, slightly resilient, and bounce reasonably well. All balls are inert and have identical mechanical properties.
  • The two ball dispensers each contain 7 balls at the start of the game. Balls are released by illuminating a light sensor located 4 inches above the table surface, in the wall at the edge of the table. When the sensor is activated the dispenser will release 4 balls. After a delay of 3 seconds, the dispenser may be triggered again to release 3 more balls.
  • Balls will be dispensed from a height of approximately 6 inches above the table surface, at the edge of the table, directly above the activating light sensor.
  • Although each ball dispenser is located on a particular side of the table, no dispenser "belongs" to a particular robot, and either robot may get balls from either dispenser; all balls have equivalent status in the game for each robot.
  • The balls may not be punctured, altered, or modified in any way.


The one-point goals are located on the sides of the board and consist of a 12 inches wide by 7.5 inches deep bin. The floor of the bin is at the table surface. The walls of the bin are 4 inches high.

The three-point goals are centered on the table, straddling the black/white division of the table. Each goal has a holding area of 5.5 inches by 23 inches. The floor of the bin is about 1/8 inch above the table surface. The common wall of the two goals is 3 inches high, the opposite wall is 1.5 inches high, and the other two sides are 2.5 inches high

Two 12 inch diameter circular hoop goals are located at the end of the table, 18 inches from the side walls. The plane of the hoop is perpendicular to the table surface and at the edge of the table. The center of the hoop is about 12 inches above the surface. An IR beacon, shining out toward the center of the table, is located below the center of the hoop, about 5.5 inches above the table surface. The beacon is modulated at either 100 Hertz (white side) or 125 Hertz (black side) with a 40,000 Hertz carrier. The robots can use these beacons to locate a particular goal from a distance. The back of the hoop is made out of net so that balls projected into the goal will tend not to bounce out. A ball remaining in the hoop goal/net at the end of the game is worth 5 points. A bonus of 5 points is awarded if the ball is shot through the hoop as described under Scoring. Top


Period of Play

  • The two robots for each game, and the side they will start on, will be chosen by random from those robots that have not played in the current round. (See Format, below.) This information will be announced during the previous game so teams may prepare their robot. The starting position of a robot defines its side of the table for scoring purposes. The contestants will have 60 seconds to place their machines on the game board from the time the judges call them to set up.
  • During the Set Up time, the start lights will be ON to aid in robot alignment. When both teams are ready, and/or the preparation time is over, the start lights will be turned off and the teams will have a few seconds to prepare their robot (typically by pushing the Choose button) to start the game when the start lights come on again.
  • The game will be started by the judges turning on the starting lights, located in the surface of the table, for the first two seconds of the game.
  • False Start Rule: A robot that fails to start as expected will be awarded a False Start, and the round will be repeated immediately. Two False Starts constitute a loss, and the robot will be removed from the table. The remaining robot will be allowed to play without opposition.
  • The powered portion of a game will last 90 seconds. Software will be provided to cut off power at the end of 90 seconds, and any machine that continues to supply battery power after 90 seconds will lose the game.
  • The game ends when both robots and all balls come to rest.
  • The judges will propose to terminate a game early if neither robot appears to be making any progress. Top

The appropriate number of points, 1, 3, or 5, will be awarded for each ball that remains in one of your goals at the end of the game. It does not matter which robot caused the ball to enter your goal. A robot's goals are those on the side of the board from where it starts, e.g. the goals for a robot starting on the white side of the board are on the white side of the board. The coloring of the goals on the diagram indicates this relationship.

A bonus of 5 points will be awarded for shooting a ball into your hoop goal at the end of the table. To receive the bonus points, your robot must cause a ball to go through the hoop while all its contact points with the board, wheel, skid or tread, are behind the centerline of the game board (away from the goal).

The machine with the most points wins the game. If there is a tie, the judges will decide the winner based on which robot that has more balls nearer to its goals, or declare a double win. If no points are scored a double loss will be awarded. Top


General Contest Rules


The Judges Rule

Contestants should ask the instructor about possible designs or strategies that may be questionable under any of the rules.

Contest rules and procedures, or even the game, may have to be altered during the semester. As much notice as possible will be given.

The judges are the instructor and any others he may designate.

The judges may alter or eliminate any rule, or add rules, at any time.

The judges will decide any discrepancies in the contest play.

All decisions of the judges are final. Top


The contest is a double elimination competition held over two days. On the first day a machine must "beat the brick" —win a game played against an inert opponent (or no opponent)— in order to qualify for the competition. Qualified machines will then play one competition round, arranged by lottery. The result of these exhibition games will be recorded but not counted for the main contest. At the end of the first day, the qualified machines will be impounded.

The main competition will take place the second day. For each round of the contest, two robots will be matched by random drawing for each game, so that at the end of the round each robot will have a recorded Win or Loss. Robots with a total of two Losses will be removed from next round and the contest. Rounds are played until only one robot remains: the Winner. For any game the judges may declare a double loss, a double win, or no result, as appropriate. See Period of Play, above, for detailed game rules. Top


Teams are encouraged to seek advice and help from any source, but the design, robot construction, and control code must be exclusively their own work.

All entries must be solely controlled by their onboard computer. There can be no human intervention once the game begins. A robot that is touched by a team member during a game will be disqualified for that round. Also, team members touching the game board during play risk disqualification of their robot.

Teams may qualify only one robot, and only that robot may play in the final round. Significant changes in robot structure or code following qualification must be approved by the judges.

Contestants may not alter the essential structure of their entry, or add/subtract significant parts, once the competition has begun, but may repair broken components between rounds if time permits.

Teams may possess only one RoboBoard controller at any one time.

A robot cannot be designed primarily to destroy the physical structure of its opponent. In particular, machines are not allowed to destroy their opponent's microprocessor board, or sensors. However, blocking, pushing, turning, overturning, or confusing an opponent is allowed.

No parts or substances may be deliberately dumped, deposited, or otherwise left to remain on the game board surface. A machine that appears to have been designed to perform such a function will be disqualified. Pieces which accidentally fall off robots may be removed from the board during a game by a judge at his discretion.

No adhesives or sticky substances (such as on tape) may be applied to any part of the game board or to a game piece (ball, block, goal, other robot, etc.)

Any machine that appears to be a safety hazard will be disqualified from the competition. Top

Robot Structure Rules

LEGO PartsOther Parts$15 RuleTop

Your robot must be constructed using the parts in your kit, with a few exceptions as detailed below (in particular see The $15 Rule). All kits contain exactly the same components, except that some LEGO parts may be colored differently in different kits. You may request additional sensors, wire, wheels, gears, and other small parts as required. After mid-term recess, the instructor will entertain requests for extra LEGO parts necessary to implement unique design features.

Some parts in the ELEC 201 kit are considered tools and may not be used on the robot. Examples are the large plastic parts container, the small rectangular parts container, the soldering iron, the sponge, etc. If there is any question about whether an object is a ``kit part'' or a ``tool part,'' ask the instructor.

The dimension of the machine may not exceed 12 x 12 x 12 inches high at the start of each round. Entries may, however, expand once the round has begun. The start light sensor must be within 3 inches of the geometrical center of your robot.

Only LEGO parts and connectors may be used as robot structure. All structurally separate parts of the robot must be connected by LEGO beams, plates, axles, etc., specifically not by rubber bands, LEGO chain links or track. Rubber bands may be used to provide stored energy, but not as primary structural elements or as linking elements between LEGO parts. Top

LEGO Parts

LEGO pieces may not be glued together, nor altered in any way, with the following exceptions:

The LEGO baseplate may be altered freely.

LEGO pieces may be modified to perform a function directly related to the operation or mounting of a sensor or motor. For example, holes may be drilled into a LEGO wheel to make an optical shaft encoder; sensors may be glued to LEGOs.

Rubber bands may be glued to LEGO wheels or gears to increase the coefficient of friction.

A maximum of five (5) LEGO parts may be cut or modified at will, or glued to non-LEGO parts other than sensors and motors. Top

Other Parts

Cardboard, other paper products, and tape may be used to create optical shields for light sensors, to line bins, or to form ramps or other elements that are not primarily structural.

Purely decorative items may be added at will, within the size limits and good taste.

Cable ties may not be used for structural purposes.

String may not be used for structural purposes.

Tape may not be used for structural purposes.

Wire may only be used for electrical purposes, not structural.

No lubricants may be used. Top

The $15 Rule

To encourage creativity, contestants may spend up to $15 of their own funds for the purchase of additional components used in their design. The following conditions apply to all non-kit additions:

No single part may cost more than $5.

Resistors rated less than 1 watt and capacitors valued less than 100 microF may be used freely, without counting toward the $15 total.

LEGO parts not issued in the standard kit but obtained outside of class, must be documented under the $15 rule.

The following components, categories of components, or varieties of circuitry are disallowed: any additional batteries; motor driver circuitry, including relays, power transistors, or any other replacements or modifications to the standard motor driver circuitry.

All non-kit parts used must be documented in a short report that includes a description of the part, or schematic of any added circuitry, and receipts for parts purchases. A part that has been obtained through means other than retail purchase will be assigned a value by the instructor. This Extra Parts Report must be signed by the instructor prior to the first round of competition, and should be kept by the team in case of a challenge. Any machines found with added parts that have not been documented in this fashion will be disqualified. Top