Rules

Robot Combat Rules

Robot combat has several organizations that develop rules of play. The rules cover both robot construction and match procedures. However, in the USA there is no national league or governing body defining local rules. The sport is still young, and each event can choose its own rules, experiment, and innovate.

Good rules ensure fair fights, impartial judging decisions, and most of all, uniform standards of safety.

Standardized rules

Here are some of the organizations which have published rules and guidelines for robot combat events. You can freely download and read any of these rules.

• Standardized Procedures for the Advancement of Robot Combat (SPARC), publisher of the most commonly used rules in the USA, covering robot construction, match procedures, judging, arena construction, and more. See SPARC rules below.
• Northeast Robotics Club, a prominent competitive organization - NERC Rules
• Midwest Robot Combat Association, an expanding network of USA Midwestern events - MRCA Rules
• Fighting Robot Association is centered in the UK - most events in Europe use their FRA Rules
• National Havoc Robot League have their own NHRL Rules
• BattleBots is a TV show with 250 pound fighting robots - BattleBots Rules are reviewed yearly

(National Robotics League is not on this list because only students on authorized teams may participate.)

SPARC rules

SPARC (Standardized Procedures for the Advancement of Robot Combat) publishes the most commonly used reference rules for robot combat events in the USA, free to download at sparc.tools. Rather than a single rulebook, SPARC is a set of documents that any event can adopt as-is or adapt. The documents point out the rules that events most often change and offer common alternatives, and an event that changes them is expected to publish its changes before the event. Event organizers discuss SPARC rule changes regularly, and the documents are updated from time to time.

The current SPARC documents are:

• Tournament Procedures – weight class names, re-weighing, unsportsmanlike conduct – SPARC Tournament Procedures v1.2
• Match Rules – activation, match length and formats, un-sticks, knock-outs, pins, emergencies – SPARC Match Rules v1.6
• Judging Guidelines – how judges score a match – SPARC Judging Guidelines v1.3
• Robot Construction Specifications – safety and build rules, weight bonuses – SPARC Robot Construction Specifications v1.7
• Restricted Class Regulations – Sportsman and Plastic classes – SPARC Restricted Class Regulations v1.0
• Arena Construction Best Practices – building a safe arena – SPARC Arena Construction Best Practices v1.1

Previous versions are kept on the SPARC archive page.

Local rules

For many bot builders, travel to multiple locations to compete isn't practical. Multi-city leagues are unusual, and unlike football, the arena of play is not standardized. So when building your robot, decide which events you plan to compete in, and check for changes to the rules from one event to another. Most events are locally run, and their rules adapt to the local requirements and situations:

• Arenas - Some arenas have metal floors, some wood; some will have pits or fences, while others do not; some arenas have thick, heavy polycarbonate windows while others can safely contain only bots with lower total weapon energy.
• Venues vary as well; in many event spaces, open flame isn't allowed, preventing the use of fire weapons. The use of power tools may be restricted to a safe area or even banished to the outdoors.
• When Volunteers are scarce or unavailable, the event may be streamlined in various ways, such as simplified judging (see below).
• Match time is most typically 3 minutes; however, if there are many competitors or other event time restrictions, two-minute matches are common.

Judging Systems

There are several different methods to judge a robot combat match.

Generally, if a robot is disabled, thrown out of bounds, or unable to travel normally on the arena floor, that the robot has lost the match.

If neither bot is disabled or disqualified, judges must render a decision. This is usually done with a point system weighted to bring out the best in bot designers and drivers, but designed never to result in a tie. For example, under the Damage and Engagement criteria in the SPARC Judging Guidelines, judges give points for Damage (4 points) and Engagement (5 points), with each shared between two opponents.

Suppose both robots appear to have suffered equal damage; each would receive 2 points using the SPARC rules. The judges must then weigh which driver better controlled the flow of the match to break the tie.

Edge cases

Event organizers may make exceptions for specific issues caused by the arena itself. For example, if bots gets jammed against the walls due to a design flaw or normal arena wear and tear, judges may direct opponents to stop the match and free a bot that gets stuck instead of counting that bot out of play. The bot's driver is expected to avoid that situation in the future.

A "one free unstick" rule may also apply to bots that have become entangled or locked together.

Damage, Control, and Aggression variant

The SPARC Judging Guidelines also offer an alternative system, the Damage, Control, and Aggression criteria (Aggression 5 points, Control 6, Damage 6). It scores control of the match situation separately from aggressive behavior toward the other bot, with Aggression, the willingness to pursue and engage the other bot, being the tie-breaking factor.

Judge's Call variant

Many events have done away with the detailed scoring system and simply have each judge indicate which bot they felt won the overall match. While this may lead to more consistent results, some builders get frustrated without scores to indicate why they won or lost the match. Different events also have different allowances for judges to talk with each other when making decisions. Some events want each judge to come to their own conclusions independently, while others think it better to have judges compare notes and discuss the results.

Outcome variant

Matches can also be judged by a simplified system based solely by the state of the robots at the end. For example:

• 2 points awarded to the survivor when the other bot is knocked out, disabled, or falls into a pit (Win)
• 2 points awarded if the opponent is disqualified or forfeits the match before it starts (Bye)
• 1 point awarded to each bot remaining in play after time expires and the match is over (Tie)
• 0 points for a bot that is knocked out, disabled, or falls into a pit (Loss)
• 0 points awarded to a bot that is not ready for combat or is disqualified (Forfeit)

This system is fine for informal matches and usually doesn't require impartial judgment. However, it's important that the term "disabled" is clearly defined and understood by all participants.

Since all types of bots must be able to disable their opponent, it's best if this variant is played in an arena with pits or other hazards that will potentially allow wedge bots and partially damaged bots a chance to win.