NHRL Open Rules - 2025

The Spirit of The Rules

NHRL Open is a competitor-centric event that prioritizes creativity, safety, and entertainment. Our rules are designed to foster innovation while ensuring a safe and enjoyable event for all participants and spectators, and are written with our core principles in mind. As the rules have been substantially modified for the 2025 season, we have created a separate page elaborating on the intent and spirit of some of the changes here: Introduction to the NHRL Open 2025 Ruleset

Core Principles

• Safety: Our paramount concern is the well-being of competitors, audience, and crew. While we aim for minimal restrictions, safety measures are non-negotiable.
• Fun: We strive to create exciting and enjoyable events for competitors and spectators.
• Competitive Integrity: We require competitors to uphold principles of fair play and sportsmanship to ensure that victories are earned through honest effort, skill, and ingenuity, rather than exploitation or non adherence to the rules.
• Innovation: We encourage and celebrate novel, interesting, and unconventional ideas in robot design and strategy. We encourage competitors to push the limits of robotic combat, provided it's done safely and enhances the enjoyment of the event.
• Inclusivity: NHRL is meant for builders of all experience levels, from newcomers to seasoned veterans. We strive to welcome and celebrate builders of all backgrounds,  providing a platform for learning and high-level competition.

Expectations for Competitors

Hosting an event in accordance with the principles above is only possible with the cooperation of an immense community of amazing competitors who are willing to help. In pursuit of hosting the best possible events, we ask the following of every member of the NHRL competitor community:

• Be excellent to fellow builders, NHRL staff, and members of the audience.
• Come to events prepared to compete in accordance with the rules.
• Take a proactive approach to safety - model safe behavior and best practices and encourage it in others. Communicate any safety concerns with NHRL staff.
• Express your passion, personality, and creativity freely, but maintain enough decorum to keep the events family-friendly and welcoming to all.
• Design and compete in good faith, with the Spirit of the Rules in mind. We encourage competitiveness and innovation in robot design and strategy, but discourage the exploitation of rule loopholes or ambiguities.
• Ask proactive questions! If you are uncertain of how something works, unsure of the intent of a rule, have suggestions on how to improve an event, or if you want to do something fun that doesn’t fit within our normal competition, reach out to NHRL as early as possible by sending your questions and ideas to hello@nhrl.io

Builder Conduct Policy

It is a privilege to be part of the Havoc Robotics and National Havoc Robot League (collectively, “NHRL”) community. Everyone who is associated with NHRL must refrain from illegal, violent, dangerous, or irresponsible conduct that is detrimental to the integrity of and public confidence in the league. We must show respect for others inside and outside our community and we must strive to conduct ourselves in ways that favorably reflect on ourselves, our sport, our teams, the communities we represent, and NHRL. As such, NHRL has established this Builder Conduct Policy (BCP), which applies to existing and former builders, builders who have registered to compete, prospective builders, and members of our social media community (collectively, “Builders”).

The BCP is intended to address and sanction conduct detrimental to the league and sport. In order to uphold our high standards, when violations of this BCP do occur, appropriate disciplinary action must follow.

Expectations and Standards of Conduct

Builders must conduct themselves in a way that is responsible, promotes the values of NHRL, and is lawful. Builders that NHRL determines have engaged in conduct that violates these rules or the values of NHRL including, but not limited to, any of the following (“Prohibited Conduct) will be subject to discipline.

• Actual or threatened physical violence against another person, including dating violence, domestic violence, child abuse, and other forms of family violence;
• Assault and/or battery, including sexual assault or other sex offenses;
• Violent or threatening behavior toward any person in any NHRL setting;
• Stalking, harassment, or similar forms of intimidation;
• Illegal possession of a gun or other weapon (such as explosives, toxic substances, and the like) in any NHRL setting;
• Illegal possession, use, or distribution of alcohol or drugs;
• Crimes involving cruelty to animals as defined by state or federal law;
• Crimes of dishonesty such as blackmail, extortion, fraud, money laundering, or racketeering;
• Theft-related crimes such as burglary, robbery, or larceny;
• Disorderly conduct;
• Crimes against law enforcement, such as obstruction, resisting arrest, or harming a police officer or other law enforcement officer;
• Conduct that poses a genuine danger to the safety and well-being of another person; and conduct that undermines or puts at risk the integrity of NHRL, its facilities, or its personnel.
• Conduct that undermines the integrity of NHRL events and competitions or violates the letter or intent of the BCP.

“NHRL setting” means any physical or virtual location or conveyance used in connection with NHRL activities, including but not limited to event facilities, offices, private or off-site events, workshops, and social media platforms.

Reporting Misconduct

If you have witnessed Prohibited Conduct by a Builder, or are aware of any incident which, if the allegations were true, would constitute a violation of the BCP, you are obligated to promptly submit a report to NHRL’s Commission.

Reports must be sent via email to complaints@nhrl.io, and must contain:

• Your full name
• Your phone number
• Date(s) and time(s) of the incident(s), as applicable
• Any relevant information or context about the nature of the incident, identity of any all parties involved (including the legal first and last name of any individual(s) and contact information, as known or available)
• Any supporting evidence, like photographs, social media activity, emails, complete and unedited screenshots or transcripts, a news article, a police report, or other materials as applicable

Upon receipt of an incident report, the Commission will review it in a timely manner, and open an investigation. The investigation may include conducting interviews with the complainant, the accused, witnesses, and/or may include contacting the authorities if the Commission deems it necessary. The timing and scope of any investigation will be based upon the particular circumstances of the matter. In conducting investigations, the Commission will make reasonable efforts to safeguard requests for confidentiality from complainants or others with information. In addition, the Commission will not tolerate, and will discipline, any retaliation, threats of retaliation, intimidation, harassment, or any other adverse action against anyone who in good faith reports a possible violation or provides truthful information during an investigation.

In certain cases when further investigation is warranted, the Commission may choose to temporarily ban or restrict any individuals who are subject to said investigation until it has concluded, at which time the temporary ban may be lifted or extended or augmented with additional discipline.

Discipline

In the event where a Builder has been found in violation of the BCP, either by being formally charged with a crime or through the course of the Commission’s investigation, the Commission will determine what, if any, disciplinary action will be taken, and communicate its decision with the necessary parties involved. This decision is final and cannot be appealed.

Depending on the nature of the violation and other circumstances, discipline may be a suspension for a fixed or an indefinite period of time, or banishment from the league and/or its digital platforms. Discipline may also include a probationary period and conditions that must be met for reinstatement and to remain eligible to participate in the league. Repeat offenders will be subject to enhanced and/or expedited discipline.

Bot Design Rules

Overview and General Requirements

In order to compete at NHRL, all robots must:

• Meet weight limits for their class
• Meet the functional requirements for movement and weaponry
• Possess the required safety features
• Obtain approval for restricted systems before competing at an event
• Be free of forbidden features

Weight Requirements

NHRL offers 3 different weight classes to compete in: 3lb, 12lb and 30lb. All robots must be at or below the maximum weight listed for their respective weight class at the start of the fight. In any given class, additional weight bonuses and exemptions may be allotted to entrants that meet certain criteria set out in this section of the rules. Competitors may not stack weight bonuses, although a single robot may qualify for both a weight bonus and one or more weight exemptions.

If a builder elects to make use of a weight bonus, they must do so before an event begins. Their robot will be locked into that weight bonus for the duration of the event.

Locomotion Based Weight Bonuses

Robots fall within one of three locomotion type categories: Traditional Locomotion, Non-Traditional Locomotion, and True Walker Locomotion. Non-Traditional Locomotion and True Walker Locomotion are given weight bonuses summarized in the following table.

Locomotion Weight Bonus Table

Weight Class	Non-Traditional Locomotion Bonus	True Walker Bonus
3 lb	1.5 lb	3 lb
12 lb	6 lb	12 lb
30 lb	15 lb	30 lb

If a robot qualifies for both a locomotion based weight bonus and a multibot bonus, the builder must choose one bonus or the other. In order for a multibot to qualify for a Non-Traditional Locomotion weight bonus, all of the segments must feature either Non-Traditional Locomotion or True Walker Locomotion. In order for a multibot to qualify for a True Walker Locomotion weight bonus, all segments qualify for True Walker segments for mobility.

NHRL has sole and final discretion on how Locomotion Based Weight Bonuses are awarded, and True Walker Locomotion weight bonuses must be approved before a robot is registered for an event.

Non-Traditional Locomotion Definition

Any robot that falls outside the definition of a “Traditional Motion System” qualifies for the Non-Traditional Locomotion Bonus. NHRL classifies Traditional Motion Systems as a robot that relies on rotational motion of a component in contact with the ground as its method of locomotion around or orientation within the arena. This includes all forms of wheels (round, non-circular, spoked, or offset axis) even if those wheels are parallel or near parallel to the arena floor. It also includes continuous tread, track or belt driven systems. This also includes vertical or near vertical spinning shafts in contact with the ground, such as weapon live shafts or similar design features.

Non Traditional Locomotion Systems may not use unpowered rotating objects (wheels, drums, rollers, ball bearings, etc.) as a means of friction reduction with the ground. They are also forbidden from using powered or unpowered wheels or wheel-like design features to ease rotation or to orient their robot within the arena. This requirement applies even when a robot is inverted or in other orientations that differ from their default orientation.

Examples of Non Traditional Locomotion Include:

• Shuffling
• Bristle Bots
• Flying Systems
• Gyroscopic Precession
• Torque Reaction
• Jansen Linkages
• Hovercrafts

True Walker Definition

True Walkers are robots with one or more legs that allow the robot to move around the arena. Legs are defined as articulating design features which contact the arena floor, which can move with two or more degrees of freedom. In order to qualify as a True Walker, locomotion must not be possible solely through the continuous rotation of one or more motors. True Walkers must also meet all the requirements for Non-Traditional Locomotion.

The total weight of spinning weapon components of a True Walker bot cannot be more than 150% of the nominal weight of their weight class - i.e. 4.5lb for 3lb class, 18lb for 12lb class, and 45lb for the 30lb class. Exceptions may be made on a case by case basis for Melty-brain designs, although lower tip speed limits may be required to maintain competitive balance.

Competitors who wish to use the True Walker Bonus *must* have their design approved by NHRL staff before registering their robot for an event. NHRL reserves the right to approve or deny any robot the True Walker Bonus at its sole discretion at any point in the season.

Multibot Weight Bonuses

A single robot entry may be divided into up to 4 segments. Robots with multiple segments may qualify for the multibot bonus, which allows for the combined weight of all segments to exceed the normal weight class limit.

Each segment of a robot using the multi-bot bonus is allotted an equal portion of the increased combined maximum weight. Unused weight from one segment may not be applied to other segments of the multibot.

Alternatively, an entry may have multiple segments without making use of the multibot weight bonus system, in which case the robot’s weight may be distributed in any way between segments. With or without a multibot weight bonus, all segments of a multibot must individually meet the mobility and weapon function requirements for their base weight class.

While not strictly required, it is strongly encouraged that multibots have a cohesive visual theme. This helps referees, judges, and spectators alike in understanding and enjoying the match.

The weight allowances for multibots making use of the Multibot Weight Bonus are summarized in the following table:

Multibot Weight Bonus Table

Weight Class	2 Part Multibot Max Segment Weight	3 Part Multibot Max Segment Weight	4 Part Multibot Max Segment Weight
3 lb	2 lb	1.33 lb	1 lb
12 lb	8 lb	5.33 lb	4 lb
30 lb	20 lb	13.33 lb	10 lb

Note that segments receiving a multibot weight bonus cannot be further subdivided - e.g. you may not have a 30lb entry with one 20lb segment and two 10lb segments.

Multibots making use of a multibot weight bonus may not begin a match physically connected to one another.

Weight Exemptions

Any bots with flamethrowers, hydraulic, pneumatic, or ICE-powered systems will be weighed “dry” (without fuel or stored operating liquids). This extends to any approved system that makes use of stored liquids or gasses, including lighter-than-air robot systems such as chambers filled with low pressure helium.

Flamethrower bots will be weighed with an empty tank installed. Competitors should bring an empty tank for weigh-in purposes.

Pneumatic and ICE-powered robots will remove their tank(s) for weigh-in. Any pneumatic tanks must be commercially available.

Competitors who bring hydraulic systems must declare in advance how much hydraulic fluid is in their system and how much it weighs. The fluid weight will be subtracted from the robot’s scale weight. These bots may be subject to random inspections, where the hydraulic fluid will be removed and measured.

Electronic components such as computer systems and sensors dedicated solely to the function of discrete autonomous systems (weapon, drive, self righting) do not count towards a robot's weight. Systems such as stability control and meltybrain directional process do not qualify. These systems must be easily removable for weight and inspection, or a competitor must be able to show the presence of these components on the robot during inspection and bring identical spare components for weigh -in purposes. These components must be approved by NHRL before an event.

Any active cameras or recording equipment on the bot do not count towards the robot’s weight but must be approved during bot inspection by a Bot Inspector. Camera systems that appear to confer a competitive advantage via additional weight will not be approved, at NHRL’s sole discretion.

Functional Requirements

Movement

Robots must be able to demonstrate controlled movement at a sufficient speed.

Robot mobility will be demonstrated during the robot inspection process. In the 3lb class, robots must be able to move at a speed of at least 10 feet per minute. In the 12lb and 30lb classes, robots must be able to move at a speed of at least 20 feet per minute. They must also be able to navigate between corners of the test box or arena. Robots that do not appear to be sufficiently mobile or controlled may be asked to complete the "Movement" portion of the NHRL Functionality Test. Robots are only required to pass a mobility test at the beginning of an event.

In a multibot, each segment must independently meet the mobility requirements.

Drones and other flying robots can compete at NHRL as long as they adhere to all other design rules. Flying robots must be able to begin matches in contact with the arena floor while all moving systems are idle or deactivated. Any competitor that operates a drone must comply with local, state and federal regulations.

Weapon Systems

All robots must have an active weapon. An active weapon is defined as a weapon or mechanism that operates independently from the robot’s drive-train or means of locomotion and is clearly designed to negatively influence the opposing robot. In a multibot, all segments must include an active weapon.

Certain robot sub-types are exempt from the requirement that the weapon system operates separately from the drive train.

• “Meltybrains”, (bots that can show controlled movement while spinning at rapid speeds)
• “Gyro Walkers” and “Torque Walkers” (bots that use spinning masses or weapons to generate inertia to induce translational motion)
• "Bristle Bots" (bots that move in part or in whole based on vibrations caused by spinning masses)

Other inventive weapon systems may be approved on a case by case basis.

"Thwackbots,” (robots which use momentum created by the robot’s drive-train to ‘actuate’ an otherwise unpowered weapon) do not qualify as having an active weapon.

NHRL strongly encourages competitors designing a non-conventional active weapon to share their plans with NHRL in advance so confirmation can be given if the weapon is deemed active or not. In the event that a ruling on a weapon is required at a NHRL tournament, the robot in question will be required to complete the "Weapon" portion of the NHRL Functionality Test.

Competitors must approach the testing process in good faith. If a robot is able to pass the weapon test but it appears (through lack of use) that the weapon was never intended to be used as tested, Tournament Stewards will be notified. Builders will be warned that they appear to be intentionally skirting weapon functionality requirements, and the robot may be disqualified or not allowed to compete at subsequent events.

Modular Weapon Systems

Modular weapon systems are defined as component assemblies that drastically change a robot’s weapon type, and that are interchangeable between fights. For example, a modular weapon system may allow a competitor to choose between a horizontal spinner and a vertical spinner configuration between fights.

Modular weapons should be designed as modules, meaning they can be bolted or otherwise attached to a robot chassis as a unit. Builders may be asked to demonstrate that they can effectively swap between modules within the minimum repair time allotted to their weight class. A modular design may be required to complete the NHRL DUMMY Test separately for each module.

All modules must be declared during Bot Inspection at the beginning of an event. Alternative modules must be presented during robot inspection (although they do not need to be installed unless requested by an inspector). Competitors may be asked to show any applicable weapon locks for the module as well.

Weapon modules may weigh no more than 50% of the maximum weight allowed for a given robot, inclusive of applicable weight bonuses.

Safety Requirements

Master Power Cut-Off Requirements

Bots must have one or more easily accessible power cutoffs that can remove power from all weapon and drive systems. Power cutoffs can be in the form of a switch or removable link. 3lb robots may use a battery connector as a removable link, but removable links on 12lb and 30lb entries must have a dedicated removable link with adequate strain relief on its wiring.

Power cut-offs must be able to be deactivated within 15 seconds. Power cut-offs must be accessible without disassembling the robot, with the exception of a small amount of tape to cover or help retain a removable link. The use of zip-ties to secure the removable portion of a removable link is not permitted.

Power cut-offs must be easily accessible. For 12lb and 30lb robots, power cut-offs must be located such that they are accessible when the robot is in its primary fighting orientation.

Power cut offs must be able to be accessed and actuated with one hand (although competitors are allowed to use both hands during the event).

Generally, it is best that power switch(es) remove all power from all systems. This avoids situations where lights or sounds make an inactive robot appear active to competitors or staff. Non-active systems (dedicated RX batteries, lighting effects, sound effects, etc) may be allowed, but competitors must disclose this during inspection for review, and must be proactive in alerting cage staff.

Battery Limitations

Nominal battery voltage may not exceed 75 volts without explicit approval from NHRL. It is understood that a fully charged battery pack will have an initial voltage above its nominal voltage.

Any robot system that produces voltages above the robot’s battery voltage limit must be approved by NHRL prior to participating in any competition and may require additional inspection. Email safety@nhrl.io to discuss your design.

Robot Control Systems

Robot controls and communication systems must pass a failsafe test overseen by a Bot Inspector at Bot Inspection in order to compete. In the event of signal loss or transmitter power-down, the bot’s drive system must stop within 30 seconds and weapons must come to a complete stop within 60 seconds.

All robots and multibot components must have a dedicated receiver(s).

Autonomously controlled robots are allowed, but they must still retain a radio control module that can remotely activate and deactivate the robot.

Size Limitations

Robots must be able to easily fit within the NHRL fire safety cart in the event of a fire or other safety emergency. The approximate inside dimensions of the fire-safety cart are 23” x 23” x 44”. NHRL will be working to expand these dimensions during the 2025 season.

Larger robots may be approved if they can be easily and immediately modified to fit into the cart - e.g. a portion of the robot can immediately be bent or removed such that the robot easily fits within the cart. Approval should be obtained before an event, and is subject to change if NHRL staff feels the robot cannot be safely enclosed in the event of an emergency.

A robot’s size and design must not be used to interfere with the procession or filming of a match. For example, you may not release umbrellas into an arena that obstruct the view of the fight.

Weapon Locks

All weapon systems must have a lock that stops their actuation, extension, expansion, rotation, ignition, etc. Weapons that move or rotate must have a lock or be constrained such that movement is restricted in all directions. This includes designs such as CAM lifters.

Weapons that shoot projectiles must have a physical means to prevent the expulsion of the projectile.

Weapons that shoot gasses, such as flamethrowers, must have their safety lock system approved before an event. Flamethrowers and similar systems must also include covers for any exposed hot surface ignitors or spark gaps.

Weapon locks that force the competitor’s fingers to be in the path of the weapon for an extended period of time will not pass bot inspection.

Weapon locks MUST be marked by an easily visible and well marked tag. Tags must be marked with “Weapon Lock”, “Remove Before Fight”, or other similar language, and must be at least 1” x 4” in size. Tags must be sturdy in construction - they cannot be paper or cardboard.

Additional information on acceptable and unacceptable weapon locks is available in Appendix B.

Restricted Robot Systems

Restricted robot systems are design features that are permitted at NHRL, but require either extra care and may require pre-approval by NHRL staff before being allowed to compete.

Internal Combustion Engines

Robots may use internal combustion engines, including piston engines, jet turbines, and other designs. Combustion engines may be manually or electrically started during load in, provided they do not cause the weapon or robot to move.

Consumable fuels and their tanks do not count towards your overall robot weight. Fuel tanks will be removed for weigh-in.

Fuel tanks containing liquid fuel must be meaningfully protected, and robots are limited to carrying only enough fuel to last for 5 minutes of runtime.

Under no circumstances is a robot permitted to intentionally eject liquid fuel into the arena. In the event of large amounts of leaked fuel, a match may be halted and the robot may be disqualified if the leak cannot be quickly and safely addressed.

Any bot that uses internal-combustion engines must go through the NHRL Design Approval Process and be approved by NHRL staff no later than three weeks before an event. NHRL strongly encourages that new designs be reviewed with NHRL staff before a robot’s design is finalized and before a robot is registered for an event.

Flame-Based Systems

Robots with flame-based systems must be able to self-light and self-extinguish. In the case of signal/communication loss with the transmitter, flame and heat-based weapons must self-extinguish in 30 seconds.

Fuel tanks containing flame system fuel must be meaningfully protected. Air gaps can be used to enhance the protection of fuel tanks, but cannot be the only means of protection. A suggested starting point for meaningful protection is ¼ inch of PLA with 30% infill for 3lb robots, and ½” of the same for 12lb and 30lb systems.

NHRL allows the use of propane, butane and other fuel sources that are gaseous at STP (standard temperature and pressure). Fuels cannot be self-oxidizing and flame systems must not include additional oxidizing systems (e.g. oxy acetylene torches and similar). Robots may use compressed air, fans, or similar means to aid in combustion, but air and fuel cannot be mixed within sealed enclosures. Matches may be stopped and your robot disqualified if, at the discretion of NHRL Staff, cage equipment, cameras or safety gear, is being excessively damaged by fire.

NHRL currently approves the following fuels for flame based weapons, with the following fuel limits for each robot weight class:

Weight Class	Fuel Limit for Propane, Butane, Isobutane
3lb	6 Ounces
12lb	16 Ounces
30lb	16 Ounces

Additional fuel types may be approved with advance notice. Currently, MAP-Pro and Plaslode fuel are under review. All means of fuel storage must be designed to default to the closed position if removed from the robot.

Any bot that uses flame based systems must go through the NHRL Design Approval Process and be approved by NHRL staff no later than three weeks before an event. NHRL strongly encourages that new designs be reviewed with NHRL staff before a robot’s design is finalized and before a robot is registered for an event.

Heat Based Systems

Heat based systems such as heat guns and soldering iron lances are allowed. Electrically heated surfaces such as glow-plugs, nichrome wire, or hot surface igniters do not require special approval or inspection processes.

Combustion based heating systems must go through the NHRL Design Approval Process and be approved by NHRL staff no later than three weeks before an event.

Plasma based systems may be approved on a case by case basis, and must go through the NHRL Design Approval Process and be approved by NHRL staff before registering for an event.

Projectile Systems

A fired projectile’s maximum speed may not exceed 300 miles per hour. Additionally, a tethered projectile must not be designed in a way that is likely to become entangled with the opposing robot.

Projectile based systems may not use ramset charges, blanks, or similar devices in their design.

Inductive Systems

Inductive systems are allowed, but may not be used to directly attack opponents. For example, you may inductively heat the tip of your own hammer, but you may not attempt to attack your opponent by inducing magnetic fields in their robot’s armor or electrical components. Competitors may be asked to demonstrate that their inductive systems do not pose an EMF based risk to their opponent and do not pose an excessive risk to arena systems like cameras.

Magnetic Systems

Externally mounted permanent magnets intended to adhere to opponents are not permitted. Permanent magnets intended for other purposes (attachment of ablative armor for instance) are allowed as long as they do not introduce an excessive risk of entanglement.  

Electromagnetic systems are allowed, but must be approved by NHRL Safety Staff, and may be required to have protective Weapon Lock style covers for use outside of matches.

Other Restricted Systems

Robots with the following systems must go through the NHRL Design Approval Process and be approved by NHRL staff no later than three weeks before an event.

• Pneumatic Systems
• Hydraulic Systems
• Any robot with components (such as spinning weapons) with speeds over 300mph.

The NHRL Design Approval Process

Any restricted feature listed in this section as requiring NHRL approval must be approved by NHRL Safety Staff.

To begin the process, competitors must email NHRL at safety@nhrl.io. Competitors should begin the process as early as possible, and no less than 3 weeks prior to the competition so that a review of the design can be conducted by NHRL Safety Staff. You will be asked to provide documentation of your design and a description of your safety processes, and NHRL staff will review the required safety procedures relevant to your design.

We cannot guarantee that any proposal sent less than 3 weeks before an event will be approved in time for the competition. Robots with unapproved designs will not be allowed to compete using their restricted systems and may not be allowed to remain in the competition venue.

Forbidden Robot Features

Rocket motors (also referred to as rocket engines), fireworks, and airbags are not allowed.

Electrical and weapons intended to directly destroy or interfere with electrical systems through electric currents or magnetic fields are not permitted. This includes EMPs, radio jammers, and tasers.

Weapons (or other robot systems) that primarily act by obstructing visibility are not permitted.

However, weapons that produce smoke or fog as a by-product of their attack are allowed.

Any system that directly targets or that may result in harm to those outside the cage is not permitted.

This includes, but is not limited to high intensity lasers, high luminosity or strobing lights, or excessively loud noises.

Entanglement devices are not permitted.

An entanglement device is defined as a component, subsystem or armor configuration that is designed to be entangled in the rotational or moving parts of an opponent.

Fabric, foam, and other ablative armor is allowed, but ablative armor must not be designed in such a way that it presents a likely entanglement risk. The decision of what is a likely entanglement risk is up to the discretion of NHRL Tournament Stewards. NHRL reserves the right during an event to require that design features be removed from a robot if those features unexpectedly prove to be major entanglement risk.

Separable features designed for intentional passive high-centering are not permitted.

Separable high-centering features encompass objects like caltrops and door stops. Also included in this ablative design features that are very obviously designed to create arena debris likely to impede robot motion. This subsection is applicable to all passive objects as well.

Design features that may present a minor risk of high centering may be allowed on a provisional basis if they have other obvious primary uses. The decision of what is a likely a passive high-centering risk is up to the discretion of NHRL Tournament Stewards. NHRL reserves the right during an event to require that design features be removed from a robot if those features unexpectedly prove to be major high-centering risk.

Liquids expelled from the robot are not permitted with the exception of bubbles made.

However, liquids expelled from a robot that become gaseous or solid shortly after leaving the robot and/or before hitting the opponent are permitted. Expelled liquids must be gaseous or solid at STP conditions.

Arena fouling systems are not permitted.

Arena fouling is defined as the release of items or materials that are excessively difficult to remove from the arena that would impede subsequent matches. A non-exhaustive list of fouling materials includes:

• Large numbers of BBs
• Gravel
• Nails shot into arena floors
• Foodstuffs or other materials that may cause issues with rotting, odor, or insects

Exceptions may me made for reasonable amounts of these materials that are actively used in weapon systems.

Most hazardous materials are not permitted.

Hazardous materials are generally not allowed within the arena, aside from those outlined elsewhere in the rules. A non-exhaustive list of disallowed materials includes:

• Strong alkali metals such as metallic potassium or sodium
• Corrosive or noxious gases such as chlorine, fluorine, or hydrogen sulfide
• Meaningfully radioactive materials

Additional Design Rules

Spare Robots

Bringing multiple copies of your robot is allowed at NHRL. Spare robots must be as close to exact copies of the original as possible. If a robot design features interchangeable parts of modular systems, all of those parts must be compatible with all spare robots.

The identity of a spare robot is defined by its chassis - the structure around which a robot is built. Spare chassis must be presented during initial Bot Inspection and will be marked by a small colored sticker. Spare robots must complete Bot Inspection before being allowed to compete. Builders that wish to switch to a spare robot must notify the Pit Desk.

Robots that do not feature a central chassis must contact NHRL before an event to determine a reasonable alternative means of distinction between spare robots.

Passive Components

Competitors may place non-robot objects within the arena with their robot at the start of a match as passive components. The combined weight of the object(s) and the robot must be below the relevant class weight limit and the segment must not conflict with entanglement or safety rules. Robots with passive components are not eligible for multibot or NTL weight bonuses.  

Passive components can be intended to break apart from robot segments, or be intended to be dropped, launched, or otherwise ejected from a segment. These components cannot be designed to act as independently operating segments of a multibot.

If a passive component is involved in an entanglement, high centering, or other circumstance that prevents the movement of an opponent, the interaction will be considered a pin. The operator(s) will be required to unpin if possible, and the situation will be handled in accordance with the entanglement rules.

Open Tournament Format

Tournament Format Summary

For each weight class, there are two separate stages: Qualifying and the Bracket. Not all bots will make it to the Bracket.

Qualifying

To qualify for the Bracket, a bot needs to win two fights over a maximum of three rounds.

The top 50% of the bots (by NHRL ranking) entered will be seeded. For seeding purposes, the number of bots will be rounded up to the next multiple of 8. For example, if 83 bots are participating in a weight class, we will seed the top 44 (half of 88). If there are fewer ranked bots than seeds, the lowest (highest-numbered) seeds will be filled by random unranked bots. All other bots will be unseeded. Seeded bots will not fight another seeded bot in the first round of the qualification stage.

In the first round, each seeded bot will fight a random unseeded bot.

After the first round, the bots that won their first fight will fight another bot that won its first round. The winner of that fight advances to the single-elimination bracket.

Bots that lose their first-round fight will fight another bot that lost its first-round fight. The loser of that fight is eliminated.

All bots that went 1-1 in the first two rounds of qualifying will then fight one more time. The winner advances to the single-elimination bracket, and the loser is eliminated.

The Bracket

The Bracket phase will be a straight single-elimination bracket ending with a final and a champion. If Qualifying is using a half-bracket (12, 24, 48, 96 bots) the top seeds for the Bracket will receive a first-round bye.

Bots are seeded into the bracket based on what fight they advanced to the bracket in. A bot that went 2-0 will get the highest seed, based on the highest possible seed that could have participated in that fight. For example, the second-round fight that would have featured the #1-seeded bot (assuming they won their first fight) would see its winner advance to the #1 seed in the bracket. Same for the #2 seed, and so on.

For bots that go 2-1, they are seeded into the bracket in a way that guarantees that a bot that lost its second-round fight will not face its opponent in the bracket, unless they both make it to the bracket final. This makes an immediate rematch for the bot that won its second-round fight impossible. Other than this restriction, they will go into the bracket in the same way that the 2-0 bots go in, by general order of the highest-possible seed likely to participate in that fight (assuming higher seeds win previous fights).

There will be no 3rd Place Playoff. Bots that lose in the semi-final can agree to fight each other but this fight would not impact World Championship qualification and would not result in ranking points.

Bots from the Same Team

During Qualifying, bots from the same team will not face each other as long as the team comprises less than one eighth of the bots in that weight class. This effort only applies for a team bringing 2-4 bots per weight class. If a team brings more, they may choose subteams, but one subteam may fight another.

Qualification for the NHRL World Championships

The semifinalists at each Norwalk tournament will qualify for the NHRL World Championships. If a semifinalist has already qualified, the quarterfinalist with the highest pre-tournament ranking will take that qualification spot.

The qualification rules for tournaments outside out of Norwalk will be communicated before those tournaments.

NHRL Freestyle Fights

Freestyle fights are a series of grudge fights run throughout the day that ensure that every builder gets to fight as much as they can. Freestyle fights do not award NHRL rankings points. All bots that participate in the Freestyle fights must pass safety.

Event Discipline

Tournament Stewards

There will be two Tournament Stewards at each event. One will be a member of NHRL staff and the other will be an experienced competitor. The Tournament Stewards’ job is to make rulings on any possible rules infractions or ambiguous rules related decisions that need dedicated attention. Any resolution needs to be agreed to by both Tournament Stewards. If the Tournament Stewards disagree, no action will be taken against the bot team.

As far as possible, the identity of the Tournament Stewards for the event will be kept hidden so that they will not receive external pressure.

In the event of a clear conflict of interest between the builder Tournament Steward, both stewards will work together to select a more objective third party to act as a temporary Steward for that specific situation.

Referees

Referees are empowered to issue warnings, TKO points, and single-point demerits. If a Referee feels that a bot team should face greater disciplinary sanctions, the Referee will report that to the Tournament Stewards.

If a referee deems that a driver is deliberately ignoring Referee or Cage Manager instructions or is fighting in the cage contrary to the spirit of the sport, they will call for a Tournament Steward to come to the cage. The fight will continue. The Tournament Steward will determine the course of action on what they have seen from the fight, from talking to the cage crew and the drivers and from reviewing fight footage, if needed. A decision will be made cageside.

Demerits

To ensure that events run safely and fairly, NHRL has a disciplinary system called Demerits. Any bot that receives 3 Demerits will be disqualified from the event. A disqualified bot is immediately removed from the tournament. Its next opponent receives a bye. In addition, a disqualified bot is not allowed to enter Freestyle fights.

Demerits will be applied to the bot and not individuals. It is the Main Driver’s responsibility to ensure that their team stays safe and within NHRL rules.

In addition to issuing Demerits, Tournament Stewards can disqualify individual bots, and decide that individual competitors must leave the building or the pits. If a bot is disqualified but individuals are not made to leave, those individuals can continue to compete with any other teams that they are registered with for the event.

Single-Point Demerit Infractions

Single-point Demerit can be given by any Referee or tournament director. These can only be given for the following listed infractions:

• Leaving a lipo battery charging unattended.
• Weapon not locked when away from the designated pit table, workshop, bot inspection area, hazard area or inside the cage (unless with express permission from NHRL staff).
• Controlling the bot or activating the weapon before cage doors are closed.
• Working with hazardous materials outside of the Hazard Area.
• Using grinding tools outside of the grinding tent or machine shop.
• Touching a functional, unlocked weapon with a hand or any other human body part.
• Appear cageside with a bot but without a bot badge or wristband.

Any potential infraction not on this list must be sent to the Tournament Stewards for an investigation. The infractions on the list can be updated by the Commission.

Tournament Steward Investigations

An investigation can be triggered by any NHRL member of staff. Competitors cannot trigger an investigation but if they observe something that should be investigated, they should inform the nearest member of NHRL staff they can find.

A Referee or Tournament Director cannot issue a single-point Demerit if this would result in the bot’s disqualification. Instead, an investigation will automatically be triggered that will review all Demerits given to the bot up to that point.

Once the Tournament Stewards receive an investigation request, they will investigate in any way they see fit. This may or may not include talking to builders as part of the investigation. When the tournament stewards have reached a decision, they will inform a member of NHRL staff to relay the decision to the relevant builder. Tournament Stewards can decide to issue any number of Demerit points, disqualify the bot, request individuals leave the pits or the entire premises, retract Demerit points, or do nothing.

To prevent unsettling competitors unnecessarily, competitors will not be informed they are under investigation unless this is strictly necessary. If the Tournament Stewards decided that no action should be taken, the competitors will not be informed that they were under investigation.

Further Disciplinary Sanctions

In extreme cases, further sanctions beyond an event disqualification may be warranted. If this is the case, the Commission will meet to decide. In line with current NHRL policies, these investigations, along with the sanctions, will be kept private between the builder and NHRL.

Fight Rules

Objective

Utilize your robot to disable your opponent’s robot by any means allowable by the tournament and design rulesets. The duration of each fight is 3 minutes, if both entrants are still mobile at the end of the 3 minute timer, the winner will be declared by judges’ decision.

Fight Start

The beginning of a fight is signaled by a countdown followed by the words “Fight, Robots, Fight!” The fight officially begins at the enunciation of the first “F” in “Fight.” During the countdown, robots must be at a full stand-still.

Robots must start the fight in their assigned corner of the arena and must be oriented such that they fit within the constraints of their classes' respective bounding box size.

Fight Results

A fight can be decided in these ways:

Knockout

Any robot that is unable to demonstrate motion will receive a 10 second count-down started by the Referee. If the countdown is completed, the robot will be considered knocked out and the fight ends.

If the robot successfully demonstrates any self-propelled motion during the 10 seconds or the robot is directly engaged by their opponent, the count-down ends and the fight continues.

For a multibot, a knockout countdown will start if more than 51% of the robot is immobile.

A knockout ends the fight immediately. Any further engagement or attacks may be referred to the Tournament Stewards.

Tap Out

All competitors have the option to “tap out” of their fight. This immediately ends the fight, giving their opponent the victory. Tap outs are considered knockouts in NHRL statistics.

Competitors tap out by hitting the TAP OUT button on their side of the cage. If the button doesn’t work, they should inform the Referee immediately that they are tapping out.

A tap out ends the fight immediately. Any further engagement or attacks may be referred to the Tournament Stewards.

Judges’ Decision

If a fight runs the full 3 minutes without a knockout or a tap out, or if the fight is stopped early (in the case of a difficult entanglement or an arena failure), the winner of the fight is determined by a panel of judges. Competitors must immediately stop engaging their opponent. The Referee will conduct a functionality check to assess each bot’s drive and weapon systems. Every multibot component will undergo the check. The Referee will determine whether the system:

• Appears fully functional
• Appears damaged but operational
• Inoperable or severely damaged

Any multibot components that do not have an active weapon will only have their drive system checked.

The referee will be determining system functionality at the time of the check. The status of the system at the time the fight ends will not be taken into account.

The winner of the fight will be determined by a panel of judges following the NHRL Judging Criteria set out in Appendix A. The judges’ decision is final and cannot be appealed.

Technical Knockout

A Technical Knockout (“TKO”) will be issued when a bot has received 3 TKO Points at a single Open Tournament. TKO Points do not roll over to other Open Tournaments. TKO Points are issued by Tournament Stewards, Referees, and Pit Crew only. If a bot receives a TKO but is not eliminated from the tournament, 3 TKO points are deducted from their total. All remaining TKO Points are still scored against the bot.

Forfeit

If a bot refuses to fight its opponent, this is a forfeit. A forfeit is considered a loss in NHRL statistics while the opponent receives a win in NHRL statistics.

Double Knockout

If neither competitor is engaging after their unstick attempts, then both bots will be counted out. If the count-out is completed and the bots engaged at any point during the fight, then the judges will decide the winner.

If neither bot engaged at all during the fight, the Referee will determine the fight winner via a coin flip.

Fight Stopped

The Referee can stop the fight before the full 3 minutes is over if both bots are stuck together and cannot be easily separated, or there is a safety issue like an arena failure. In this case, the fight will be treated as a Judges’ Decision. The Referee has the final decision on all competitor conduct during a fight.

False Starts

At the start of the match, all parts of all robots must be completely stationary. Any non-kinetic and internal systems should remain in their unpowered and stationary failsafe states until the fight officially begins. For example, flame ignitors should be at roughly ambient temperature and internal flywheels should be stationary.

The only exception to this rule is that ICE systems can be in an “idle” state until the fight begins.

Systems that utilize springs, onboard air compressors, or other potential-energy based systems are permitted to “charge” their system before the match begins, but the charge systems must be inactive at the beginning of the match.

Any bot component that moves out of its unpowered and stationary failsafe state before the fight starts will be deemed to have committed a false start. If no contact is made with the opponent bot, one TKO Point will be given to the offending bot. If contact is made with the opponent bot, the offending bot will receive three TKO Points and an automatic TKO.

Fight Resets

A fight reset may occur at the Referee, event organizer, or production team’s discretion.

When a fight reset is called, robots must stop fighting immediately. Both robots are then re-positioned to their starting corners, and the fight timer is reset.

Unstick Attempts

During the course of a fight, robots may get flipped or stuck in an orientation such that they cannot demonstrate self-propelled motion. In each match, competitors are entitled to one unstick attempt from the housebot. However, in the event that the housebot is unable to perform an unstick whether by faults or malfunctions internal or external to the housebot, the referee will notify the competitors and their allotted unstick attempt will be waived.

There is no guarantee that an unstick attempt will be successful. Additionally, it is possible that either robot may get damaged or end up in a less favorable position than they started when the unstick attempt was called.

When an unstick attempt is called, the housebot will drive to the impaired robot and try to right/free/reorient it. The effort will start slowly and deliberately, then gradually become more forceful.

Calling for an unstick attempt does not pause the match, or mandate that your opponent stop attacking.

Unstick attempts must be called for using the button box on the side of the cage. Verbal unsticks can be requested if the button box is not working correctly.

An unstick attempt officially starts at the time of the request and will generally last no longer than 25 seconds.

In the event that a competitor’s opponent has impeded a housebot’s unstick attempt, the housebot driver may spend additional time performing the unstick at their discretion. Additionally, the housebot may retaliate against any robot that takes aggressive action against it, regardless of whether it is with the intent of delaying an unstick.

Pins

A pin occurs when a robot is actively preventing their opponent from moving. This includes, but is not limited to lifting, grappling, blocking, or forcing against a wall. Pins are used by Judges to help score fights.

A pin is counted as a pin when it is held for 5 seconds but it must not last more than 10 seconds. At the end of the pin, the pinning robot must release their opponent by giving them sufficient space to escape.

If the pinning bot does not release the pin within 10 seconds, the Judges will disregard the pin. If the pin results in an entanglement (see below), the Judges will disregard the pin.

In the case of a flame robot pinning an opponent, the flame robot must disengage its flame system for the pin to be considered released. This can be accomplished by turning the flame system off, creating a large amount of distance between robots such that the flames become obviously ineffectual, or by pointing the flame system away from the opponent until the referee indicates the aggressing robot may reengage.

Disentanglements

Though NHRL prohibits the design and use of entanglement devices, it is still possible that robots may become entangled with each other by accident. The Referee determines if bots are entangled. Multibot components from the same bot that are entangled with each other are not considered an entanglement.

If a housebot is able to successfully separate two stuck robots, it will not be ruled a disentanglement, nor will it count for either robot’s unstick attempt.

If entanglement lasts more than 10 seconds and cannot be rectified by the house bot, the match will be paused, and the referee will attempt to separate the robots manually.

If the referee is unable to safely separate the robots, or if either robot is unable to drive at the end of the disentanglement, the match will end, and the winner will be determined by judges’ decision.

Any unpowered “props” that a competitor includes in their robot must not be made with the intention of high-centering their opponent. If a prop high-centers its opponent during a fight, and its design is such that NHRL staff determines that it was an intended outcome, this may be considered deliberate entanglement.

If a bot is ruled by NHRL to have deliberately entangled its opponent, then it will be considered to have lost that fight by TKO.

A bot that is ruled to have accidentally or unintentionally entangled its opponent may win its fight. However, our judging criteria states that any damage caused by entanglement is disregarded by our judges and not considered for damage scoring.

Props that are deemed to be likely of causing additional entanglement will not be allowed in future matches.

Hazardous robots and behavior

If the Referee or Tournament Stewards deem a robot to be a hazard to the crowd, crew or competitors, or if a robot is inflicting considerable damage to the arena, the Referee may elect to end the fight early. In this case, the winner is determined by judges’ decision.

If a bot fouls the arena in such a way that the arena’s condition is materially impacted and there is no reasonable application of the fouling material, the bot will be immediately disqualified by the Tournament Stewards and there will be potential for further punishments. Glitter, bubbles, and confetti are not materials that can foul the arena.

Event Rules

Entering the Pits

All competitors must sign a NHRL Waiver Form. All competitors must have a valid wristband to enter the Pits.

Match Readiness

All bots are guaranteed a certain amount of repair time between the end of any given fight and the start of the next fight. 3lb bots get 20 minutes, 12lb bots get 25 minutes, and 30lb bots get 30 minutes.

Any bot that is not ready to fight 10 minutes before its scheduled fight time can use a single-use repair extension of 15 minutes. This extension can only be used once per event and any unused minutes cannot be used later at the same event. The bot will receive 1 TKO point for using the extension.

If the bot is still not ready after the 15 minute extension, or if the extension has already been used, the bot will receive 3 TKO points and an immediate TKO.

The repair extension cannot be used for the Quarterfinals, Semifinals of Finals of the Bracket in any weight class.

Bot Inspection

Before a robot’s first fight at an event, it must pass a bot inspection, during which a Bot Inspector will ensure the bot is in compliance with all design and safety rules. Robots must pass bot inspection before they are able to fight. If the bot has not passed bot inspection before it is due to fight, it will receive 3 TKO points and an immediate TKO.

The bot inspection process consists of:

• Weapon lock/weapon cover check.
• Checking that sharp edges are adequately covered when not fighting.
• Radio fail-safe testing for weapon and drive systems.
• Demonstration of general design requirements.
  • Active weapon and controlled motion.
  • Switch/removable link operation.
  • Any other functional, weight or design requirements specific to the robot’s design or weapon type.
• Multibot segment check.
• Deceleration of any additional weapon modules
• Robot weigh-in (including weapon modules).
• Arena fouling material check.
• Camera equipment approval (if needed).

If a Bot Inspector is not confident that a Bot’s drive or weapon meets minimum functionality standards, they may be required to run a functionality test on the bot. A bot that fails its functionality test may not fight in the tournament unless they are able to improve their bot to the point that it passes the test. Bots that do not pass functionality tests may stil fight in Freestyle fights.

Robots will not pass bot inspection if they are overweight.

All weapon modules a team wishes to use at a given event must be inspected. Any weapon module that has not passed bot inspection before that robot's first fight will not be eligible to fight at the event. Passive configuration changes (like unpowered forks/wedges, fireproof tape, or anti-drone poles) do not need a full bot inspection but can be put through bot inspection to confirm they are not considered an entanglement device.

If material that could foul the arena is found, the Bot Inspector will warn the Main Driver, but the bot will still pass bot inspection.

Design Changes and Check-ins

When a team checks into the Pit Desk with a bot, they must bring it in the state that they intend to fight it in. They may not change the design, switch between weapon modules, alternate multibot segments, or change components like forks, wedges, or armor after checking in at the desk before their fight. Similarly, bots cannot be replaced with spared after they get to the Pit Desk.

Pre-Fight Weight Checks

All competitors will be required to weigh their bots before each fight.

If a bot is overweight by up to 2.5oz it will be given 1 TKO point. If the team can quickly reduce the weight, they will be allowed to fight assuming the bot has not received 3 TKO points.

If a bot is over 2.5oz it will receive 3 TKO points and an immediate TKO.

A set of official calibrated NHRL scales will be made available in the pits for builders to use at any time to check their bot weight.

Cage Load-In

Competitors must arrive at the cage with their bot unpowered and with weapon lock installed. The must have their transmitter(s), wristbands and bot badge for the team.

When cage-side, all competitors must follow directions from Referees and Cage Managers. Bots cannot use their drive or weapons systems at any time when the doors of the cage are open.

After the doors close, cage staff will direct competitors to demonstrate the functionality of their drive and weapon systems. Robots must display the ability to move within the arena, and they must show that their weapon is at least partially functional. Robots do not need to meet the standards set out by the functionality test at this point, but they must be meaningfully functional.

Bots will be able to perform any additional tests inside the cage that they wish as long as the test can be completed within 1 minute. If it takes longer than 1 minute, this will incur one TKO point. If it takes longer than three minutes, three TKO points and an immediate TKO will be issued.

If, during load-in or during the functionality demonstration, a bot needs more work done to it than removing the weapon lock, powering it on, or performing a power cycle, the team will receive 1 TKO point and a maximum of one minute to get the bot ready to fight. If the bot is unable to fight after one minute, it will receive 3 TKO points and an immediate TKO. If more than half the multibot segments fail to function then an immediate TKO will be issued.

In the case of multibots, if half or fewer of the multibot segments are not working, the team can fight with the remaining functional segments. They can choose to include the non-functional segments in the match, but this will have a significant impact on judges’ scores.

If a competitor leaves the cage area for any reason, they are not permitted to return to the cage area until after the fight has finished.

Safety Rules

NHRL and the NHRL community works hard to create a safe environment for competitors, staff, and fans. The following rules are a starting point, but builders are encouraged to learn and follow best practices modeled by the community and are required to follow any additional safety direction given by NHRL staff.

Battery Charging

• Any time a battery is charging, it must be attended by a builder or team member.
• Any lithium-chemistry battery must be charged using balance leads.
• If a battery catches fire or presents a safety hazard, make the situation as safe as possible and alert NHRL staff immediately.

Hand and Power Tools

• Safety glasses and other appropriate PPE must be worn while working with power tools in the pits or machine shop.
• Power tools that produce sparks, dust, or shrapnel may only be used in the workshop or in the designated “cutting and grinding” area in the pit.
• Power tools that produce flames or lasers may only be used in the workshop.
• 3D printers must not be left running overnight.

Weapon Locks

A weapon lock is defined as a mechanism or component that will keep your weapon from being dangerous when your robot is not in the cage.

Generally, a weapon lock must be used whenever your robot’s weapon system and batteries are installed. Weapon locks may only be removed:

• Immediately before a match
• During the photo portion of bot inspection
• During weight checks
• At the direction of a Referee, Cage Manager, Bot Inspector, or other NHRL safety official.

When your weapon system battery is disconnected or removed, or the weapon system is disassembled to the point of non-functionality, weapon locks are not required. Weapon locks should be installed as quickly as is feasible after final assembly..

While not strictly required, it is best practice that a weapon lock be installed when an assembled robot is left unattended, even if the batteries are not installed.

Robot Testing

All robot weapon and drive testing must be done in a test box. The only exception to this rule is ‘Wheels-up’ testing for robots with a second dedicated switch for their weapon systems.  

Robots may not be driven on the floor of the pits, around the competition venue, or outside the test box, regardless of their weapon status.

Disassembled weapon and drive power systems may be powered on and bench tested at low speed provided they are fully disconnected from the weapon - i.e. you may bench test bare motors or servos. Use best practices and ensure motors are properly secured.

Robot Hazard Station

The Robot Hazard Station is an extension of our pit safety efforts. It ensures that potentially hazardous processes are done in a controlled and safe environment outside of the pits. Failure to use the hazard station appropriately may result in demerit points.

The Robot Hazard Station must be used for the following:

• Loading and unloading fuel for internal combustion engines
• Loading and unloading fuel for flame based systems
• Pressurizing or depressurizing all pneumatic systems
• Post-fire robot inspection and clean-up in the event that a robot is rushed out of the building after a fight.

Robot Hazard Station Rules:

• No more than 3 teams with 2 representatives each in the station at a time.
• Use appropriate PPE when working in the station.
• Do not charge batteries in the Robot Hazard Station.
• If recovering from a fire, talk to the hazard station attendant for a check-in

Alcohol and Intoxication

Though alcohol is served at NHRL, it is never allowed in the pits or workshop, nor is any active competitor or team member allowed to drink alcohol during a competition. Team members may not arrive intoxicated to an event, and may be subject to disciplinary action if they do so.

Appendix A: Judging Criteria

This criteria covers judging for head-to-head matches for full-combat bots.

Each judge rates the competitors across 3 categories: Aggression, Control and Damage. A judge allocates 6 points to the competitors for each of Control and Damage, and 5 points for Aggression. The bot with the most points is that judge’s choice. If there is a panel of 3 judges, the bot that is chosen by at least two judges wins the match.

When a judges’ decision is required, a recording of the fight will be watched by a panel of 2 judges. If both judges choose the same winner, that bot will win the fight. If the judges choose different winners, a third tiebreaker judge will watch the same recording of the fight and choose the winner.

For the quarterfinals of the single-elimination bracket onwards, a panel of three judges will watch the fight live and each will choose a winner. The bot that is selected as the winner by at least two of the judges will win the fight.

The judging process and number of judges on each panel will only vary from these two scenarios if there are technical issues requiring the activation of contingency plans.

All judges' decisions are final.

For example, consider a match between bots Foo and Bar that goes to a panel of 3 judges:

Judge	Aggression	Control	Damage	Winner
A	Foo 2, Bar 3	Foo 4, Bar 2	Foo 1, Bar 5	Bar 10-7
B	Foo 2, Bar 3	Foo 5, Bar 1	Foo 2, Bar 4	Foo 9-8
C	Foo 2, Bar 3	Foo 3, Bar 3	Foo 2, Bar 4	Bar 10-7

The winner of the match would be Bar, by split decision.

Aggression

Aggression is the intensity and frequency of intentional attacks, preferably with an active weapon. To score points here, the bot needs to make attacks that could conceivably affect the opponent.

Gaining Aggression Points

The key to aggression is attacking intensely and/or frequently with an active weapon, and an intention to affect the opponent. Missed attacks do not count toward aggression.

Whether the attack actually affects the opponent through damage or control is not important when scoring aggression. However, the intent to affect the opponent is important.

For example, a bot that uses a powered lifter to attempt to tilt its opponent against the wall will score aggression points, as they are attacking with an active weapon with an intent to affect them.

If a bot’s weapon is disabled, but it is still attacking with intent, it scores aggression points as if the weapon were working.

A bot that attacks consistently over the length of an entire match should score more aggression points than a bot that clumps all its attacks into a short duration of the match but spends significant portions of the match not attacking.

Losing Aggression Points

If a bot attacks without intent to do damage, even with a functional weapon, it should score even fewer aggression points. For example, striking an opponent’s armor repeatedly with a tapping stick would score very few to no aggression points, as there is no intent to affect the opponent. However, attempting to jam the tapping stick into an opponent’s spinning weapon would score aggression points, as there is an intent to affect the opponent’s weapon systems.

If a bot declines to engage its opponent, does not use its active weapon, or is technically unable to engage for a significant period of time, it should lose aggression points. This includes robots that spend a significant portion of the fight avoiding physical contact. Bots that are clearly attempting to use their active weapon but are unable to due to the actions of their opponent should not be penalized. Note that a bot that drives away from contact briefly to prepare its weapon should not lose aggression points, nor should a bot that shows willingness to attack its opponent but is circling briefly to find an opportunity.

Tiebreaker Considerations

In the case of effectively equal aggression the judges shall slightly favor the robot with the still functional weapon if one bot has lost weapon functionality.

If both bots have seemed to use active weapons equally as frequently, then consider how often they each used passive weapons like fixed wedges as a tiebreaker.

If both bots spend a significant portion of the fight not using their active weapon to attack, then attacks with passive weapons should be considered when determining aggression during those portions of the fight.

A bot that consistently waits for its opponent to engage or otherwise relies on its opponent creating engagements will be treated as less aggressive than a bot that actively searches for attack opportunities. This should only be factored into scoring when the aggression score is effectively at the midpoint between levels in the aggression matrix.

Other Factors

If both bots hit each other with their active weapons simultaneously and one gets sent in the air, both are showing equal aggression.

A bot being faster does not inherently make it the aggressor. A slower bot may demonstrate aggression by consistently moving toward its opponent in an attempt to attack even if the speed differential between the two bots makes this difficult.

Bots do not get aggression points for interfering with the house bot.

When scoring a fight with a multibot entry, consider the aggression of each segment of the multibot. If any portion of a multibot spends a significant portion of the fight avoiding engagement this should negatively impact the entries overall aggression score. This would not apply to a multibot segment that was rendered non-functional. Additionally, a multibot segment without a weapon being used as part of an attack involving an active weapon counts as aggression for the entry as a whole. To the degree practical the overall aggression score for a multibot should be the average of the scores you would assign to each individual segment. For segments that were rendered non-functional during a match their weighting should be balanced based upon the portion of the fight in which they were functional.

Aggression Judging Matrix

• 5-0:
  • This bot used its active weapon to attack its opponent with intent for almost the entire match. The opponent spent almost all of the match not actively attacking with an active weapon using intent.
  • The opponent spent almost the entire match actively avoiding engagement.
• 4-1:
  • This bot frequently used its active weapon to attack its opponent with intent. The opponent occasionally used its active weapon to attack its opponent with intent.
  • This bot often used its active weapon to attack its opponent with intent, but only for part of the match. The other bot rarely or never used its active weapon to attack its opponent.
  • The opponent spent a significant portion of the match actively avoiding engagement.
• 3-2:
  • This bot used its active weapon to attack with intent slightly more than its opponent.
  • Both bots’ active weapons were at least partially disabled, but this bot tried to attack more with its disabled weapon than its opponent.
  • This bot attacked consistently throughout the match with its active weapon. Its opponent bunched its attacks over a shorter period of the match but spent long portions of the match not attacking.

Control

Control is how well a bot dictates the flow of the match. To score points here, a bot will be putting its opponent in a bad spot, like pinning it or getting it stuck.

Gaining control points

The key to control is seeing your opponent put in a bad position. This could include:

• Inverting them
• Pinning them
• Getting them stuck against the wall
• Getting them stuck on a rough patch on the floor
• Getting them stuck on a side that the bot was not capable of self-righting from
• Getting them stuck on debris

Pinning a bot should not count as much as leaving them in a stuck position.

A bot that unsticks its opponent demonstrates more control than a bot that lets the house bot do the unstick. A bot that unsticks itself demonstrates more control than a bot that needs the house bot to unstick it.

If Bot A is able to use Bot B’s weapon against itself, then Bot A is considered to be showing control.

If Bot A acts in a way which prevents Bot B from successfully attacking with their weapon, then Bot A is considered to be showing control.

Following a weapon to weapon impact a robot should only gain control points if the outcome is one of the robots being put in a bad position once the bots have stabilized following the impact.

Losing control points

If a bot successfully pins their opponent but is unwilling to release the pin prior to the completion of the refs 10 count does not gain control points. A bot that is unable to release a pin without house bot intervention does not gain control points.

If a bot sticks itself, that counts as if it was stuck by its opponent (although see the tiebreaker rule below).

A bot should be stuck or inverted long enough to affect the flow of a match in order to lose control points. A brief period of being stuck (e.g. getting a fork stuck in a divot for a second or two) or inverted should not count against a bot for control.

Tiebreaker considerations

If bots seem to control the match equally, shift your focus to each driver’s control of their bot as a tiebreaker. Was the driver in control of their bot, or did they seem to frequently lose control of it? If one bot stuck itself, then the other bot should get more control points.

Other factors

Bots do not get control points for interfering with the house bot.

Long periods of neither bot maintaining control should be considered when determining the final score spread. Frequent, extended periods of no clear controlling bot should bring the overall score closer to an even split.

When scoring a fight with a multibot, focus on the overall control of the entry as a whole. A robot facing a multibot that uses one of the segments of the multibot against another segment of the multibot counts positively for the singular bots control score. Similarly, a multibot entry where the segments regularly interfere with each other counts negatively toward the multibot’s control score.

If a multibot segment is unwilling or unable to interact with the opposing robot this should negatively impact their control score.

In a situation where Bot A pins one multibot segment of Bot B it would gain control points. If another segment of Bot B were to attempt to pin Bot A into the already pinned portion of Bot B that does not gain control points. In this circumstance, if the second segment of Bot B prevents Bot A from releasing a pin this will not count as Bot A being unable to release their pin.

Control judging matrix

• 6-0:
  • This bot pushed the other bot around the cage at will, repeatedly putting them into bad situations while never itself being put in a bad situation.
  • The other bot got stuck far more often.
• 5-1:
  • This bot was able to get the other bot in bad positions in the cage several times, while it got put in bad positions occasionally, but less frequently.
  • The other bot got stuck somewhat more often.
• 4-2:
  • This bot got the other bot in bad positions slightly more often than it was put in bad positions.
  • The other bot got stuck slightly more often.
  • Both bots were stuck in bad positions about the same amount, but the other bot stuck itself in bad positions more.
• 3-3:
  • Both bots seemed to control the match equally.
  • Neither bot seemed to take control of the match.

Damage

Damage is the condition of the opponent’s bot at the end of a match compared to how it started. To score points here, a bot needs to hurt its opponent’s critical systems.

Gaining damage points

Damage is the relative state of the bot at the end of a match, as compared to at the start of the match. The highest damage score is awarded to the complete destruction/disablement of a subsystem, followed by the reduced effectiveness of a subsystem, damage to critical structural components, damage to ablative components, and lastly aesthetic or cosmetic damage.

Self-damage is weighted as being equal to damage from the opponent.

If a bot’s active weapon does not work from the very start of the match, or if its drive is compromised at the very start of the match, this will count as damage.

To score damage points, a bot must alter the state of their opponent’s bot. When scoring damage, consider this chart, where the most damage points is at the top (Class F), and least is at the bottom (Class A). The more damage a bot sustains, the higher its damage class, and the more damage points its opponent will score.

• Class F: At least half of the drive system and all weapon systems on the bot are disabled.
• Class E: At least half of the drive system or all weapon systems on the bot are disabled. This includes removing a spinner’s weapon belt so it no longer spins. An articulated weapon, like a hammersaw, must be completely disabled to count here; that is, both the saw and the arm must be disabled.
• Class D: Reduced effectiveness of drive or weapon systems. This includes at least one wheel removed or damaged such that the bot's ability to drive in a straight line is significantly compromised, disabled powered stabilization features like internal flywheels, a partially-disabled articulated weapon (disabling either the saw or the arm, but not both), or a cut flamethrower line so that the bot sprays fire on itself.
• Class C: Structural damage, like a damaged frame, significant damage to non-ablative armor, removed forks/wedglets, or a wheel damaged in a way that moderately changes a bot’s function. Examples of this would include a wheel being damaged such that the robot is consistently bouncing as the wheel rotates or the robot has some difficulty driving in a straight line, large gouges in a wedge that expose what it was protecting to attack, or wheel guards being removed.
• Class B: Most ablative armor removed from at least one side, small gouges/holes in non-ablative armor that doesn’t significantly hinder function, or a wheel or wheels damaged in a way that doesn’t noticeably change a bot’s mobility. Examples of this would include chunks of the wheel being removed or torn but not impairing the ability of the wheel to spin freely or causing noticeable driving issues.
• Class A: No more than cosmetic damage, like scratches against paint or some ablative armor removed.

Ablative armor is any non-structural component intended solely to absorb damage by being consumed.

Completely running out of fuel (i.e. flamethrower fuel and ICE fuel) does not count as damage, even though it would disable a weapon. Running out of electrical or pneumatic power does count as damage.

For multibots, average out the difference of damage classes between the multibots, rounding towards a higher damage class.

Multibot scoring

For any multibot segments without an active weapon class E damage will be scored as class F damage.

If a multibot segment avoids participating in the fight it will be excluded from the damage calculation.

Example 1: If one half of a multibot finished at class C and the other half finished at class F, consider the bot at class E (Class C is the 3rd damage tier, class F is the 6th damage tier. 3+6=9, 9/2=4.5, rounded up that’s 5 and the 5th damage tier is Class E).

Example 2: For a 3 part multibot consisting of Segment 1 at class B, Segment 2 at class A, and Segment 3 at class F, consider the bot at class C (A+B+F=9, 9/3=3, making the overall damage class C). The same approach applies for a multibot consisting of any number of segments.

Other factors

Bots do not get any damage points for damaging the house bot.

In most cases, any damage done to a bot is considered damage against it, whether it was dealt by its opponent, dealt by a house bot, or self-inflicted. The only exception to this is if a weapon has been stopped through entangled debris in its mechanism from an opponent. In that case, damage is not counted against it.

Damage judging matrix

• 6-0:
  • There are at least 4 classes separating the two bots. For example, one bot is at class F, and the other bot is at class B.
• 5-1:
  • There are 3 classes separating the two bots. For example, one bot is at class D, and the other bot is at class A.
• 4-2:
  • There are 1-2 classes separating the two bots. For example, one bot is at class E, and the other bot is at class F.
• 3-3:
  • Both bots are in the same damage class.

Appendix B: Weapon Lock Examples

A good weapon lock is clearly obvious as a weapon lock, has a sole purpose of being a weapon lock, does not fall out easily (even if the bot is dropped), and can be inserted and removed with one hand.

NHRL may test to see if a weapon lock is sufficiently secure by shaking the robot in different orientations to see if the lock remains in place.

Here are some good weapon locks (note that weapon locks now require weapon lock tags in line with the design rules section: