Competition Rules

Overview

2005 marks the third year that the BYU Robot Soccer competition will have multiple players per team. We'll adopt many of the rules of the RoboCup Smallsize (F-180) league, particularly those for the size of robots and the field, and we'll try to be consistent with their style of play. Over time, the continuing improvements in play in our senior project competition may help us create a competitive team that can represent BYU in the smallsize league.

This document describes the rules of our competition for Winter Semester 2005. Differences from the rules of the RoboCup Smallsize league will be highlighted.

The equipment

Our competition will be held on the playing field located in the senior project room (498 CB). The field is green with black markings and is not to be modified by participants in any way without prior approval. Unlike the current RoboCup fields, ours will continue to use the side ramps and side walls that keep the ball in play. The length of the field is 2900 mm and the width is 2400 mm. All walls will be painted black and the tops of the goals will be clear. No penalty markings will be painted on the field and standard RoboCup rules regarding placement of the ball during penalties will not be followed. Unless the class votes otherwise, a standard orange golf ball will be used as the soccer ball. The ball is approximately 46 g in mass and 43 mm in diameter.

During competition, each team will have one dedicated workstation on which all their team and vision code must run. A single camera suspended over the field will be connected to one of the workstations to allow for image processing. Each team will be provided with a single wireless transmitter and multiple receivers to send commands from the workstation to your robots. Different types of RF hardware may not be used; each team must make sure they are operating on a unique frequency. During competition, only the two teams playing should have their transmitters turned on. Jamming of the other team's RF communications is prohibited.

Each team is responsible for the physical design and construction of their robots. A MagiccBoard for each robot will be provided to each team to provide control on board each robot. (The number of robots per team is limited to the number of MagiccBoards provided.) In addition, each team will be supplied with a fixed number of high-quality motors and batteries. Other components may be selected from available equipment in 416 CB; you are not allowed to remove equipment from old robots for your own use, but you are free to examine their hardware and to purchase or build your own. (With recent expenditures to make the necessary MagiccBoards and to buy new smaller motors, we have little money left to reimburse you for any major purchases. In the interest of keeping the competition fair, please use the equipment provided whenever possible.) Low cost items such as wheels, wiring, connectors, and the vehicle chassis should be paid for by each team. Note that all hardware additions made by teams are turned over at the end of the semester for future Robot Soccer competitions.

Before a game, each of the two teams has a color assigned, namely yellow or blue. Each team must be able to use either yellow or blue markers. Square markers of the assigned color must be mounted on top of the robots. The center of the marker must be located in the visual center of the robot when viewed from above. The markers must be at least 40 mm square. Robots may use black and white coloring on the top without restriction. Robots may also use green and pink markers. Only the colors provided by the TAs may be used in the construction of the tops. With the exception of the top of each robot, everything that is visible to the overhead camera (including the robot sides when on the edge of the field) must be black – i.e. no shiny metal.

Each robot must fit inside a 180 mm diameter cylinder; the maximum height is 150 mm, including the colored markers on the top. At no time during competition can anything (e.g., a kicker, dribbler, or other movable part) extend beyond this 180 mm limit.

Competition format

The final tournament will consist of a sequence of head-to-head matches or games. Each match will consist of two three-minute halves; the clock for each half will be stopped by the referee only for timeouts and in the event of something outside the normal scope of play (at the sole discretion of the referee). The clock will continue to run when goals are scored and when fouls are called. The halftime period separating the two periods of play will not exceed two minutes. Once a game is over, the teams playing the next match will have up to three minutes to prepare before their game begins.

Each team will have two timeouts per match, each lasting just 30 seconds. Timeouts can be called only when play is stopped after a goal, after a foul, or if the ball leaves the playing surface (assumed to be rare). During a timeout, robots may be touched and lifted by team members. Except during a timeout, robots may not be touched once play begins. Each team is limited to two members in the immediate vicinity of the playing field (even when play is stopped) to avoid congestion. (During play, everyone should move back to keep from obstructing the view of others.)

The team at the top of the bracket is the home team. The home team starts the game defending the south goal with the yellow top markers unless both teams agree otherwise. In addition, the home team will be the first to kickoff. Before play begins, teams are responsible for ensuring that they are using different transmission frequencies. Unless both teams agree otherwise, teams will change directions and colors for the second half and the team that did not kickoff to start the game will kickoff to start the second half.

At the start of each half, the ball will be placed near the middle of the center circle. All robots must be on their own side of the field. Robots on defense can be no closer to 300 mm from the ball until the Play command is issued; robots on offense can be placed anywhere on their side of the field. Once placed, robots are free to move, but they must stay on their own side and cannot contact the ball until the referee signals the start of play. In an effort to make the competition format spectator-friendly, we need to stick to strict timing constraints. (The exact details will be worked out as needed.) Failure to place a robot in the allotted time may require your team to begin play without that robot on the field. Robots taken off the field for any reason may be replaced on the field to resume play only during a stoppage of play: after a goal or after a foul has been called.

Once play begins, it continues (under normal circumstances) until a goal is scored, a foul is called, or time expires. To handle notification of goals and fouls, we have implemented a simplified version of the RoboCup Referee Box that will send your team code a message with the details. When you are notified that a goal has been scored, your robots must move (autonomously) back to your side of the field to prepare for the kickoff. (You will be notified if you will be on offense or defense.) When you are notified that a foul has occurred, your robots must move themselves into position after the ball is placed by the referee. Failure to do so in a timely fashion may require the removal of the offending robot from the playing field, at the direction of the referee. Specifically, once a kickoff, foul, or goal command has been sent, robots have 5 seconds to position themselves. If any robot is in violation of the rules after the 5 seconds have expired, it will be removed from the field. A player removed in this way cannot reenter the field until there is a stoppage in play (typically a goal or a foul). If the referee places the ball and a robot makes contact with the ball while repositioning itself for a kickoff or a penalty kick, the offending robot will be removed from the field of play until the next stoppage of play. This is admitted a severe penalty, but it is easily avoided; make sure your team responds appropriately to all referee box directives and avoids the ball when repositioning itself.

When a goal is scored, the referee will place the ball near the center of the field by hand; in case of a foul, the referee will place the ball for a free kick wherever he deems appropriate. In either case, once the ball is placed, defensive robots must immediately move at least 300 mm from the ball. The clock continues to run, but play will not resume until signaled by the referee (through the referee box). On free kicks, offensive robots can move to any desired location. (No off-sides calls will be made in our competition at any point.) For simplicity, all free kicks will be considered direct kicks, allowing the robot taking the kick to score directly without another robot touching the ball. All referee calls concerning goals and fouls are final.

With the walls on our soccer field, the ball should go out of play only rarely, so we will not implement RoboCup's throw-ins, corner kicks, and goal kicks. Play will be stopped if the ball ever leaves the playing surface, in which case it will be placed back on the field in a neutral position (most likely near the center). If one team repeatedly causes the ball to leave the field of play (say because its robots have powerful kickers that are not well controlled), fouls may be called at the sole discretion of the referee, including an arbitrary placement of the ball to resume play. In the event that the ball becomes stuck on the playing field in such a way that neither team can make progress, the referee may move the ball or temporarily stop play at his discretion.

In matches ending in a tie after regulation where a winner must advance, the teams will play sudden-death overtime periods of 3 minutes until a goal is scored. Between each overtime period, there will be a short 90-second break.

Playing rules

Robots are not allowed to "carry" or "hold" the ball. The ball cannot be controlled in such a way that opponents would be unable to flip it away if they were well positioned. Nothing can be used to physically attach the ball to the robot (e.g., adhesive, suction). Concave openings in the perimeter of robots that allow unfair control of the ball are prohibited. According to RoboCup rules, 80% of the diameter of the ball must be visible from directly above and outside the convex hull of the robot; from any perspective (including a side view) 80% of the diameter of the ball must be visible.

There will be no designated goalies in our competition so RoboCup rules specific to the goalkeeper will not apply. We will, however, enforce RoboCup rules prohibiting multiple players of either team inside the "defense area", defined to be the rectangular box in front of each goal. At most one robot of each team can be entirely within the defense area. (Some leniency will be given to defensive robots if the violations are temporary and do not substantially change the outcome of the current play.) This rule prevents teams from employing a defensive strategy of positioning all robots side-to-side directly in front of the goal.

Unless the teams vote to enforce it, we will not enforce the RoboCup rules of unsporting behavior for robots on the field that are not capable of moving.

Soccer is a contact sport, and physical contact with other players is unavoidable, but we wish to promote a finesse game that focuses on individual skills and well-executed teamwork. Like RoboCup, we emphasize the no-contact principle and encourage you to pay particular attention to obstacle avoidance algorithms that will allow you to avoid collisions with other robots. In particular, aggressive or uncontrolled movement that could result in damage to any robot or the playing field is unacceptable and inconsistent with the spirit of our competition.

Within the defense area, fouls will be called if an offensive robot makes contact with any defensive robot where the point of contact is within the defense area. Outside the defense area, fouls will be called on a robot making "substantial contact" with an opposing robot. The RoboCup rules committee gives this definition:

Substantial contact is contact sufficient to dislodge the robot from its current orientation, position, or motion in the case where it is moving. When both robots are moving at similar speeds, and the cause of contact is not obvious, the referee will allow play to continue. This law is designed to protect robots which are slow moving or stationary at the time of the contact, and as such should be detected by obstacle avoidance systems.

To this we add the following: if a robot is moving and has the ball in its control (steady contact with the ball) and an opposing robot runs into the ball in such a way that the robot with the ball takes the energy of the collision, a penalty will be called as if the opposing robot had collided directly with the robot with the ball. In other words, if an opposing robot is moving downfield with the ball, your robot cannot cause a head-on collision by moving into the ball in the opposite direction. However, your robot may get in front of the robot with the ball and wait for the ball to come to it. (Think basketball here: you can draw a charge but you can't be moving into the offensive player.) Another legal option for your robot is to flick the ball away (perpendicular to the direction of travel of the robot with the ball), but this would be difficult since both robots are moving and your robot must avoid making substantial contact with the other robot as it steals the ball.

Robots repeatedly committing such fouls may be carded and ejected. If aggressive or uncontrolled play causes damage to an opposing robot, the fouling team may be penalized by loss of match or (depending on the severity of the damage) disqualification from the entire tournament. Penalties and disqualifications will be assessed at the sole discretion of the referees.

Any aspect of play not covered in this document and any interpretation or clarification of these rules must be directed to the referee for validation. All referee decisions are final.

Referee Box Commands

Referee Commands will be issued to teams over a TCP/IP network connection. The score, the time remaining in the half, which half is being played, and an integer indicating the state of the referee will be sent every second. The following commands can be sent:

Halt
TimeoutHomeTeam
TimeoutAwayTeam
FoulHomeTeam
FoulAwayTeam
GoalHomeTeam
GoalAwayTeam
KickoffHomeTeam
KickoffAwayTeam
Play

Halt

Whenever the Halt command is issued, the robots on both teams are required to cease movements. This command will always be issued before any of the other commands (with the exception of the Play command).

TimeoutHomeTeam, TimeoutAwayTeam

Timeouts can only be called after the ball is dead – i.e. when a foul is called or a goal is scored. This command will be issued after the Halt command. It will be followed by the appropriate goal or foul command depending on what stopped the match in the first place. TimeoutHomeTeam means that the home team has called a timeout. A timeout will stop the clock.

FoulHomeTeam, FoulAwayTeam

Foul commands will be issued when the referee has determined that a foul has been committed. FoulHomeTeam means that the home team has committed the foul. The clock will not stop for fouls. A Halt command will be issued before the Foul command is sent. The Foul commands will not be sent until after the referee has placed the ball in the place to be kicked from. When the Foul command is sent, the robots should set up for a foul kick. The Foul commands will be followed by the Play command, at which time, the kicking team should kick the placed ball.

GoalHomeTeam, GoalAwayTeam

When a goal is scored, the Halt command will be sent to both teams. After the referee has placed the ball back in the center of the field, the appropriate Goal command will be sent. GoalHomeTeam means that the home team has scored a goal. The Goal commands should instruct the robots to set up for a kickoff where the team that has just been scored against is kicking off. The Goal commands will be followed by the Play command, indicating that the match should resume. The clock will not stop for a goal.

KickoffHomeTeam, KickoffAwayTeam

These commands will be issued at the start of the halves. KickoffHomeTeam indicates that the home team is to kickoff. The Kickoff command will be followed by the Play command, at which time the kickoff should occur.

Play

The only time the robots should be playing soccer is when the Play command is being sent. All other commands are setup commands and will be followed by this command.