SCAR 2025 Ruleset​

Based on SPARC Robot Construction Specifications v1.5
Updated February 2025
Text colored in red are under review and are defaulted from existing SPARC Rules.
​Please contact SCAR if your robot uses any of the system outlined in the red text.

​
  
All participants build and operate robots at their own risk. Combat robotics is
inherently dangerous. There is no amount of regulation that can encompass all the
dangers involved. Please take care to not hurt yourself or others when building,
testing and competing.

If you have a robot or weapon design that does not fit within the categories set
forth in these rules or is in some way ambiguous or borderline, please contact the
event organizer. Safe innovation is always encouraged, but surprising the event
staff with your brilliant exploitation of a loophole may cause your robot to be
disqualified before it ever competes.

Each SCAR event has safety inspections. It is at the sole discretion of SCAR’s safety inspectors and volunteers that your robot is allowed to compete. As a builder you are obligated to disclose all operating principles and potential dangers to the inspection staff.

At SCAR events, all robots are required to have their name visible in some form on the robot.  This is to help the event run smoothly with having robots that are easy to find and inform them of upcoming matches and scheduling.  This can be done in a cosmetically pleasing fashion, or, SCAR can provide a sticker during event registration and check-in.


Cardinal Safety Rules
Failure to comply with any of the following rules could result in expulsion or worse, injury and death.

Radios that do not operate using spread spectrum technology may not be turned on at or near events for any purpose without obtaining explicit permission from the event. SCAR solely recommends 2.4ghz transmitter/receivers at this time.

Proper activation and deactivation of robots is critical. Robots must only be activated in the arena, testing areas, or with expressed consent of the event and it's safety officials.

All robots must be able to be fully deactivated, which includes power to drive and weaponry, in under 60 seconds by a manual disconnect.

Locking devices/ “Weapon Safety” 
Moving and spinning weapons that can cause damage or injury must have a clearly visible locking device in place at all times when not in the arena. Locking devices are encouraged to be highly visible from a distance. These devices must be clearly capable of stopping or otherwise preventing harmful motion of the weapon. Locking devices must securely remain in place on the robot such that they cannot easily come loose or fall off without intent.  

Weapon locking pins must be in place when weapon power is applied during a robot’s power-on procedure. This includes all powered weapons regardless of the power source or weight class.

It is expected that all builders will follow basic safety practices during work on the robot at your pit station. Please be alert and aware of your pit neighbors and people passing by.


Weight Classes and Weight Bonuses
SCAR offers a number of weight classes for competitors to compete in, from Fairyweight (150 grams) to Featherweight full combat (30lb) depending on the event. All weight classes are allowed up to a 5% weight bonus for on-board video camera/streaming devices, and these devices must be able to be removed if requested by the opponent prior to a match. The standard, or “base,” weight for each division is defined by a wheeled drive system.

SCAR has chosen to combine multiple categories of alternative-locomotion into the broad category, eligible for up to 150% weight bonus, as “Non-wheeled Motion” which includes but is not limited to the following methods for motion:

  • Gyro Walkers (Kitten Mittens, Rickety Cricket) - Gyroscopic forces used in conjunction with a rotating arm that tilts a portion of the robot to generate motion
  • Torque-Reaction (Droopy, Ditto) - Torque reaction of a powered system to generate motion
  • Bristle Drive (Depth Charge) - Vibration of a powered system to generate motion

A 125% weight bonus is available for robots who use a "Shuffler" or "Shuffling" mechanism, or rotational cam operated legs
Fairyweight
150g - Base Weight
187.5g - Shuffler
225g - Non-Wheeled Motion

Antweight
1lb / 454g - Base Weight
1.25lb / 567g - Shuffler
1.5lb / 681g - Non-Wheeled Motion

Plastic Antweight
1lb / 454g - Base Weight
1.25lb / 567g - Shuffler
1.5lb / 681g - Non-Wheeled Motion

Beetleweight
3lb / 1362g - Base Weight
3.75lb / 1701g - Shuffler
4.5lb / 2043g - Non-Wheeled Motion

Hobbyweight
12lb - Base Weight
15lb - Shuffler
18lb - Non-Wheeled Motion

Featherweight
30lb - Base Weight
​37.5lb - Shuffler
45lb - Non-Wheeled Motion

Plastic Antweights
The spirit of these classes is to have an easy entry point for new builders and to encourage creative designs by limiting materials to plastics that are easy to work with, commonly used in 3D printers and don’t have strength characteristics common in the standard classes. Components used for structure, armor, and weapons must be 3D printed.

PET, PETG, ABS, ASA, PLA, or PLA+ are the only materials that can be used for the chassis and weapons. No other types of plastics or materials allowed (ie. metal, carbon fiber, UHMW, etc).

At their discretion, event organizers may allow additional plastics or disallow that meet the spirit of the rules.

Non-plastic parts such as motors, electronics, axles, fasteners and adhesives can be any material, but cannot be used in such a way to enhance the structural integrity, armor the robot, or enhance any weapon. 

Magnets to enhance traction or downforce are prohibited from Plastic Antweights. Foam is allowed for wheels and
padding of electronics.

Robots may be disqualified at the Event Organizer’s discretion if it is deemed to violate the spirit of the class. Contact the event organizer ahead of time if you are not sure your robot meets the above definition.

For more details about Plastic Antweights, please visit the Plastic Ant FAQ

Mobility
All robots must have easily visible and controlled mobility in order to compete. These methods of mobility include but are not limited to:
  • Rolling (wheels, tracks or the whole robot)
  • Non-wheeled (no perpendicular rolling elements in contact with the floor)
    • Shuffling (rotational cam operated legs)
    • Ground effect air cushions (hovercrafts)
    • Gyro Walkers (Usage of rotating a spinning assembly for its gyroscopic forces for motion)
    • Torque Reaction (Accelerating or braking one or more spinning masses for motion)
    • Bristle (Similar to Torque Reaction but with a continuous rotation for motion)
    • Jumping and hopping may be allowed at some events, contact the event organizer if you’re intending on using this as a method of locomotion.
    • Please contact the event organizers if you have any questions about weight bonuses.

Sportsman Class
.A robot may be entered in the “Sportsman” class if it complies with the additional rules in this section. Any robot may be entered in the “standard” class of the same weight.
  • Active Weapon Required.
    • Your bot must include an active weapon or device. These include but are not limited to lifters, hammers, clamps, spinning weapons (within limitations, see below), etc. Weapons such as a fixed spike that require the movement of the bot to function do not qualify as active weapons.
  • Limitations on Spinning Weapons.
    • All devices rotating more than 360 degrees are allowed to operate with a tip speed at or below 20ft/s.
    • (Approximate tip speed = no load RPM * diameter in inches * 0.00436) Weapon rpm may be measured by tachometer prior to the start of the event. Specific weapons of sufficiently high mass or moment of inertia (MOI) may be limited to lower speeds or disallowed by officials if they deem the weapon to be too destructive. Officials may require submission of specifications including motor voltage, gearing ratio, weapon weight and dimensions prior to the event.
    • Sawing, drilling and other spinning weapons will be allowed to exceed the 20ft/s limit so long as they meet the following requirements:
      • The effective tooth pitch for the saw or saw like weapon is ≥5. (Effective pitch = tooth count / diameter) For example, a 10” saw blade with 60 teeth would meet this requirement. A 10” saw blade with 40 teeth would not. For abrasives the grit size will be used to determine if the requirements are met. (T ooth count = grit * circumference.
    • Saws and saw like weapons are limited to the manufacturer's rated RPM. If you are using a custom blade it will be limited to the rated rpm of an equivalent commercial blade. (± 5% on tooth count, diameter , thickness)
    • Additionally, the maximum spinning mass for saws and saw-like weapons is 15% of the total bot mass. This includes any mounting hubs, shafts, flywheels, pulleys, and other structures mechanically linked to the rotation of the saw blade. For Sportsman Beetles this limit is 7.2oz / 204g. for Sportsman Feathers this limit 4.5lb.
    • Wheel-like and rubber spinning weapons are allowed without a specific tooth density requirement. Excessively destructive implementations may be restricted at the event organizers discretion.
    • All weapons operating above the 20ft/s limit must be submitted to the event organizer for approval during the registration period.
  • Wedge Limitations.
    • Active wedges are allowed with no restrictions. A robot may only have a single passive wedge.
    • An active wedge is defined as a wedge that articulated and actuated independently of the drive system.
    • A passive wedge is any wedge or wedge like object (forks, series of small, hinged, independent wedges along the same face of the robot) that does not meet the requirements for classification as an active wedge.
    • At the event organizers discretion any weapons being primarily used as a passive wedge may be required to undergo modifications to reduce or remove this potential prior to continuing in a tournament should this use result in the robot being in violation of the restriction on the number of passive wedges permitted.
  • Excessively Destructive Weapons.
    • Weapons deemed too destructive by virtue of their mass, MOI or other characteristics may be further limited or disallowed at the discretion of the event. Please contact the event organizer concerning your design to avoid problems.
  • Standard SCAR Rules Apply 
    • Unless otherwise stated, all other standard SPARC rules will apply. This includes Shuffler and Non-Traditional weight bonuses. However, a walker that uses the weight bonus for a spinning (or other) weapon that is too destructive will be disqualified.



Robot control requirements
All combat robots must be radio controlled. At this time 2.4gHz is the primary frequency used, and any other method of control must be approved by the event organizer before the event.

Tethered control is not allowed.

Radio systems that stop all motion in the robot (drive and weapons), when the transmitter loses power or signal, are required for all robots. This may be inherent in the robot’s electrical system or be part of programmed fail-safes in the radio.

All robot radio systems must have a way to change frequencies or coded channels to prevent radio conflicts. Digital spread-spectrum radios that use frequency hopping or automatic channel selection qualify under this rule.

Toy radio systems (27mhz, 49mhz, or Bluetooth) are not allowed.

SCAR does not require a separate power switch for the radio.

Autonomous/Semi-Autonomous Robots:
Any robot that moves, seeks a target, or activates a weapon without human control is considered autonomous. If your robot is
autonomous or semi-autonomous you are required to contact this event before registration for approval.  There are specific guidelines for autonomous robots which can be provided and must be met in order to compete, and if these are not met the robot will not be entered into the tournament.

Batteries and Power
The only permitted batteries are ones that cannot spill or spray any of their contents when damaged or inverted. This means that standard automotive and motorcycle wet cell batteries are prohibited. Examples of batteries that are permitted: gel cells, Hawkers, NiCads, NiMh, dry cells, AGM, LIon, LiFe, LiPoly, etc. If your design uses a new type of battery, or one you are not sure about please contact the event you’re planning to attend.

All onboard voltages above 48 Volts or 12S LiPo require prior approval from this event. (It is understood that a charged battery's initial voltage state is above their nominal rated value.)

All electrical power to weapons and drive systems (systems that could cause potential human bodily injury) must have a manual disconnect that can be activated within 15 seconds without endangering the person turning it off. (E.g. No body parts in the way of weapons or pinch points.) Shut down must include a manually operated mechanical method of disconnecting the main battery power, such as a switch (Fingertech, Whyachi, etc) or removable link. Relays may be used to control power, but there must also be a mechanical disconnect.

All efforts must be made to protect battery terminals from a direct short and causing a battery fire.

If your robot uses a grounded chassis you must have a switch capable of disconnecting this ground. ICE robots are excepted from this rule if there is no practical way to isolate their grounding components. You must contact this event for this exception.

All Robots must have a light easily visible from the outside of the robot that shows its main power is activated. This can include lights from speed controllers or other electronics through translucent plastics in robots 3lb or less, regardless of whether the robot has a weapon.

Pneumatics
Pneumatic systems on board the robot must only employ non-flammable, nonreactive gases (CO2, Nitrogen and air are most common). It is not permissible to use fiber wound pressure vessels with liquefied gasses like CO2 due to extreme temperature cycling.

You must have a safe and secure method of refilling your pneumatic system.

9.2.1. SPARC recommends the use of standard paintball fill fittings available at
many retail outlets and online. For specs see Part#12MPS from Foster,
http://www.couplers.com.
9.3. Exemptions
9.3.1. Robots 12 lbs and under and systems with gas storage of 2 fl oz or less are
exempt from the remaining rules in this section provided that the maximum
actuation pressure is 250 PSI or less and all components are used within the
specifications provided by the manufacturer or supplier. If the specifications
aren't available or reliable, then it will be up to the EO to decide if the
component is being used in a sufficiently safe manner.
9.3.2. Pneumatic systems with pressures below 100 PSI, small volumes (12-16g
CO2 cartridges), single firing applications, or pneumatics used for internal
actuation (as opposed to external weaponry) may also be exempted from the
remaining pneumatic rules. You are required to contact this event if you would
like an exception.
9.4. All pneumatic components on board a robot must be securely mounted. Particular
attention must be made to pressure vessel mounting and armor to ensure that if
ruptured it will not escape the robot. (The terms 'pressure vessel, bottle, and source
tank' are used interchangeably)
9.5. All pneumatic components within the robot must be rated or certified for AT LEAST
the maximum pressure in that part of the system. You may be required to show
rating or certification documentation on ANY component in your system.
9.6. All pressure vessels must be rated for at least 120% of the pressure they are used
at and have a current hydro test date. (This is to give them a margin of safety if
damaged during a fight.) If large actuators, lines, or other components are used at
pressures above 250psi these will also need to be over-rated and are to be pre-
approved for this event.
9.7. All primary pressure vessels must have an over pressure device (burst/rupture disk
or over pressure 'pop off') set to no more than 130% of that pressure vessels
rating. (Most commercially available bottles come with the correct burst assemblies,
use of these is encouraged)
9.8. If regulators or compressors are used anywhere in the pneumatic system there
must be an (additional) over pressure device downstream of the regulator or
compressor set for no more than 130% of the lowest rated component in that part
of the pneumatic system.
9.9. All pneumatic systems must have a manual main shut off valve to isolate the rest of
the system from the source tank. This valve must be easily accessed for robot de-
activation and refilling.
9.10. All pneumatic systems must have a manual bleed valve downstream of the
main shut off valve to depressurize the system. This bleed valve must be easily
accessed for deactivation. This valve must be left OPEN whenever the robot is not in
the arena to ensure the system cannot operate accidentally.
9.10.1. It is required to be able to easily bleed all pressure in the robot
before exiting the arena. (You may be required to bleed the entire system if it
is believed that you have any damaged components.)
9.11. All regulated pneumatic systems must have an appropriate gauge scaled for
maximum resolution of the pressure on the low-pressure side of the system. HPA
(air, nitrogen, or inert gas) systems must have gauges on both the high AND low-
pressure sides of regulators. A gauge or other clear visual indication that the system
is charged is strongly recommended for all pneumatic systems. Whether specifically
required or not.
9.12. If back check valves are used anywhere in the system you must ensure that
any part of the system they isolate can be bled and has an over pressure device.
9.13. Any pneumatic system that does not use a regulator, or employs heaters or
pressure boosters, or pressures above 2500psi must be pre-qualified by the event
you’re planning to attend.


Hydraulics10.1. Robots in the 12 lb class or lighter are exempt from the remaining rules in
this section, but good engineering and best practices must be used in all hydraulic
systems. However the pressure for 12 pound or less robots is limited to
250psi and there must be an easy way to determine this pressure. Contact
the event with any questions.
10.2. All hydraulic components onboard a robot must be securely mounted.
Particular attention must be made to pump and accumulator mounting and armor to
ensure that if ruptured direct fluid streams will not escape the robot.
10.3. All hydraulic components within the robot must be rated or certified for AT
LEAST the maximum pressure in that part of the system. You may be required to
show rating or certification documentation on ANY component in your system.
10.4. Any accumulators or large reservoir must be rated for at least 120% of the
pressure they are used at. (This is to give them a margin of safety if damaged
during a fight)
10.5. All hydraulic systems must have an over pressure by pass device set to no
more than 130% of the lowest component rating. It must be rated to bypass the full
volume of the hydraulic pump.
10.6. All hydraulic systems must have a(n) accessible manual bypass valve(s) to
easily render the system harmless.
10.7. All hydraulic systems must have appropriate gauges scaled for maximum
resolution of the pressures in that part of the system.
10.8. All hydraulic systems must use non-flammable, non-corrosive fluid and must
be designed not to leak when inverted.
10.9. Any hydraulic system using pressure boosters, or pressures above 5000psi
(without accumulator) or pressures above 2000psi (with accumulator) must be pre-
qualified by the event.
10.10. Please note that some simple low pressure and volume hydraulic systems,
like simple braking, may not need to adhere to all the rules above. You are required
to contact the event if you would like an exception.
11. Internal Combustion Engines (ICE) and liquid fuels are typically not allowed, however
some events/venues do allow them.
SPARC Robot Construction Specifications v1.4
8 October 2023
Copyright © 2023 SPARC
SPARC Standard Ruleset v1.4
11.1. Fuel and Fuel Lines
11.1.1. All commercially available grades of automobile or RC hobby fuel are
allowed. Alcohol, Nitro-methane, jet fuel and other specialty grades of fuel
require prior approval.
11.1.2. Fuel lines and tanks must be made of high quality materials and all
ends must be clamped securely.
11.1.3. All fuel tanks and lines must be well protected and armored from all
sides including moving parts and heat sources inside the robot.
11.2. Fuel tank volume, on any robot, shall not be greater than the amount
required to operate the engine for more than 1 minute longer than the match
time at combat power plus a reasonable pre-match warm-up period. Total fuel
volume, including fuel for both ICE and flame weapons (if allowed) may not exceed
20 oz unless prior approval is granted from this event.
11.3. The output of any engines connected to weapons or drive systems must be
coupled through a clutch which will decouple the motor when it is at idle. (This does
not include motors used for generators and hydraulic pumps.)
11.4. Any engine connected to a weapon must be capable of being started while
the weapon locking pin is in place (see 3.4.6).
11.5. All engines must turn off or return to idle at loss of radio signal and turn off
at loss of radio receiver power.
11.6. All engines must have a method of remotely shutting off.
11.7. Any robot with liquid fuel and oil must be designed not to leak when inverted.
(Minor oil leakage may be tolerated, however if it affects the other robot or becomes
a large cleanup issue you may be called and the leaking robot will forfeit.)
11.8. Use of engines other than standard piston engines (i.e. turbines etc.) require
prior approval for any event.

Spinning Weapons
Spinning weapons must come to a full stop within 60 seconds of the power being removed using a self-contained braking system.

Spinning weapons cannot exceed 250 miles per hour at the weapon tips. If competitors are found to be exceeding this limit, they risk immediate disqualification. This limit can be imposed with software limits within a radio or controller settings.

Springs and flywheels
13.1. Springs used in robots in the 12 lbs class or smaller and those loaded simply
by the weight of the robot(eg. suspension systems) are excepted from the rules in
this section. However safe operation and good engineering are always required.
13.2. Any large springs used for drive or weapon power must have a way of loading
and actuating the spring remotely under the robot’s power.
13.2.1. Under no circumstances must a large spring be loaded when the robot
is out of the arena or testing area.
13.2.2. Small springs like those used within switches or other small internal
operations are excepted from this rule.
13.3. Any flywheel or similar kinetic energy storing device must not be spinning or
storing energy in any way unless inside the arena or testing area.
13.3.1. There must be a way of generating and dissipating the energy from
the device remotely under the robot’s power.
13.4. All springs, flywheels, and similar kinetic energy storing devices must fail to a
safe position on loss of radio contact or power.


Forbidden Weapons and Materials
The following weapons and materials are absolutely
forbidden from use:
  • Weapons designed to cause invisible damage to the other robot. This includes  but is not limited to:
    • Electrical weapons
    • RF jamming equipment, etc.
    • RF noise generated by an IC engine. (Please use shielding around  sparking components)
  • EMF fields from permanent or electro-magnets that affect another
         robot’s electronics.
  • Entangling Weapons or defenses 
    • These are weapons or defenses that can reasonably be expected to stop drive train and/or weapon motion by being wrapped around rotating parts. This includes nets, tapes, strings, and other entangling materials or devices.
  • Weapons or defenses that that can reasonably be expected to stop combat completely of both (or more) robots.
  • Weapons that require significant cleanup, or in some way damages the arena to require repair for further matches. This includes but is not limited to:
    • Liquid weapons. Additionally a bot may not have liquid that can spill out when the robot is superficially damaged.
    • Foams and liquefied gasses
    • Powders, sand, ball bearings and other dry chaff weapons
    • Un-tethered Projectiles
  • Fire is forbidden as a weapon in all weight classes at the time of this document. This includes, but is not limited to the following:
    • Flammable liquids or gases
    • Explosives or flammable solids such as:
    • DOT Class C Devices
    • Gunpowder / Cartridge Primers
    • Military Explosives, etc.
    • Light and smoke based weapons that impair the viewing of robots by an entrant, Judge, Official or Viewer
  • Hazardous or dangerous materials are forbidden from use anywhere on a robot where they may contact humans, or by way of the robot being damaged (within reason) contact humans. Contact the event you plan to attend if you have a question.

Special weapon descriptions allowed at some SCAR events:
Heat-based weapons ar allowed at SCAR events. The subsequent rules in this section apply when heat is allowed. Flame and Heat weapon rules are subject to change to comply with local fire regulations and fire officials. Please check with SCAR Directors before registering to compete with these type of weapons.
15.2.1. Fuel must exit the robot and be ignited as a gas. It cannot leave the
robot in a liquid or gelled form or use oxidizers.
15.2.2. Fuel types allowed are propane and butane, the maximum quantity
allowed is 4 fl oz in robots up to 30 lbs, 8 fl oz for robots 60 lbs and above.
15.2.3. The fuel tank must be as far from the outer armor of the robot as
practicable and be protected from heat sources within the robot.
15.2.4. The ignition system must have a remotely operated shut-off that
allows the operator to disable it using the radio control system.
15.3. Smoke Effects are not allowed at this event.
15.3.1. Small smoke effects may be used, please contact the event if you plan
on using it.

​