Please join us at our next meeting on ???.


CIRC collaboration is enhanced by the CIRC Yahoo Group

Magazines we read:


Stores we frequent:

  logo_pololu   logo_labjack AutonomouStuff           AM6inch-01    


Packt Logo


Donations in any amount are gratefully accepted. Thanks!


Central Illinois Bot Brawl RC Combat Rules

The following rule set has been adapted from the RFL and SPARC guidelines.

Last Updated: 4/16/17


  • 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.
  • This rule set is designed for adjustment by each event depending on its safety concerns.
  • If you have a robot or weapon design that does not fit within the categories set forth in these rules or is in someway ambiguous or borderline, please contact this event. 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.
  • Compliance with all event rules is mandatory. It is expected that competitors stay within the rules and procedures of their own accord and do not require constant policing.
  • Before the competition all competitors must complete a safety inspection. It is the event organizer’s sole discretion that your robot be allowed to compete. As a builder you are obligated to disclose all operating principles and potential dangers to the inspection staff.

Match Rules

  • Matches will be 2 minutes in length
  • Once both robots are loaded in the arena and the doors are closed, competitors will be provided a short duration (<20 seconds) to test their weapon and drive system before the match starts
  • Any competitor that moves their robot before the start of match countdown finishes will be given a warning and the robots and timer will be reset. If the competitor violates the countdown again they will be disqualified and the other competitor will be awarded a win for the match.
  • The arena trap door will open 30 seconds into the match
  • Any robot that fall into the trap door pit or is immobilized across the opening will be considered incapacitated
  • If both robots fall through the trap door simultaneously which ever robot passes through the plane of the opening first will be considered incapacitated first. If it’s not obvious which robot fell in first the decision will be made by the event judges.
  • Tap-Out buttons will be provided for competitors to signal if they wish to stop the match and for confirming they are ready before the beginning of the match. We also recommend shouting “TAP-OUT” to alert your competitor as quickly as possible.
  • If a robot has ceased moving in a controlled manner but has not tapped out the referee will begin a 10 second countdown. If the robot is unable to demonstrate controlled translation movement before the countdown ends it will be declared the loser by KO.
    • Controlled translational movement is defined as being able to traverse in a manner such that the net movements of the robot are in a linear direction.
  • Competitors must cease operation when the timer expires, their opponent taps out, or the judge signals a pause.
    • If a competitor fails to cease operation when required they will be given a warning then disqualified on their second offense.
  • Competitors will be responsible for removing their own robots from the trap door pit.
  • Competitors can only immobilize or capture their opponent for 10 seconds at a time. After this time they must release and separate but can capture their opponent again after at least 10 seconds has elapsed. Examples of immobilization scenarios include:
    • Pinning your opponent against the arena wall
    • Capturing the other robot with an active weapon such as a clamp or grabber mechanism
    • Trapping your opponent between your robot and the pit opening
  • If both robots are simultaneously made immobile the match may be temporarily paused to restart the robots at the judges discretion.
  • If a robot becomes stuck under the arena’s inner barrier wall, on a floor seam, or another scenario where the arena was to blame for the stick and is unable to free themselves they are allowed one “un-stick” per match. Competitors must notify the event organizers if they wish to make use of their one “un-stick” at which point the match timer will be paused. If the robot becomes stuck on the arena as a result of the opponent then an “un-stick” cannot be requested.
  • Robots that are trapped on top of the arena wall or between the inner and outer walls will not be unstuck are are considered immediately knocked out. Competitors must power off their weapons and stop all robot motion in this scenario. This rule is intended to minimize arena damage and potential risk to spectators/competitors.
  • If the match timer elapses and neither robot is disabled nor has either competitor tapped-out, the winner will be determined by a judge’s vote utilizing the SPARC Simplified Judging Criteria.

Rumble Rules

  • Unless otherwise stated below all of the standard match rules apply to the rumbles
  • Combat rumbles will be 4 minutes in length
  • The arena trap door will open 30 seconds into the rumble
  • Antweights are allowed to participate in the Beetleweight rumble
  • There are no “tap-outs” during the rumble but competitors are expected not to intentionally attack immobile robots
  • There are no “un-sticks” available during the rumble either between robots or robots and the arena
  • When only one robot is still capable of controlled translational movement the match is ended and they are declared the winner
  • If multiple robots are still operational at the end of the rumble all robots still capable of controlled translational movement will be presented to the audience for a vote to decide the winner
  • Competitors must wait until the rumble is over before retrieving their robot from the pit

Cardinal Safety Rules:

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

  • Radios may not be turned on at or near events for any purpose without obtaining the appropriate frequency clip or explicit permission from the event.
  • 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 .
  • All robots with active weapons must have a light easily visible from the outside of the robot that shows its main power is activated. This is highly recommended but not required for weapon-less robots as well.

Locking Devices/Safety Covers

Moving 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 must be clearly capable of stopping, arresting or otherwise preventing harmful motion of the weapon .

  • 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.

Any sharp edges or points must have safety covers to avoid injury. These must only be removed once the robot is inside the arena and reinstalled before removing the robot from the arena. Some examples include:

  • Spinning weapons with pointed “teeth”
  • Spikes and needles
  • Wedges with very sharp edges

Weight Classes

  • This event offers tournaments for 1lb (antweight) and 3lb (beetleweight) combat robots.
  • At this time, fully-autonomous robots are not allowed entry.
  • Multi-Bots are allowed in all weight classes. When 50% or more of the total robot weight is incapacitated the entire multi-bot is considered incapacitated.
  • There is no weight bonus for shufflers or other forms of locomotion.
  • If fans, lighter-than-air devices, or anything else is used to generate lift or additional down force during the match these will not be included when measuring robot weight during the initial check-in.
    • The CIRC arena employs a wooden floor so magnets will not provide any benefit to robot down force.

Size Limitations

Robots must be no larger than 12″ X 12″ X 12″. This is to insure that robots can pass through the arena door and trap door openings without issue. If a robot becomes immobile over the pit opening but does not fall through the trap door they will be considered incapacitated.

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.
  • CIRC event organizers may also deny entry to a robot if its weapon causes excessive damage to the arena during normal operation. Some damage is expected in the course of combat but we wish to avoid robots that damage the arena whenever their weapons are active or very frequently without contacting their opponent. Please contact the event organizer concerning your design to avoid problems.


All robots must have easily visible and controlled mobility in order to compete. Methods of mobility include:

  • Rolling (wheels, tracks or the whole robot)
  • Non-wheeled: non-wheeled robots have no rolling elements in contact with the floor and no continuous rolling or cam operated motion in contact with the floor, either directly or via a linkage. Motion is “continuous” if continuous operation of the drive motor(s) produces continuous motion of the robot. This excludes “shufflers” but linear-actuated legs and novel non-wheeled drive systems may qualify.
  • Shuffling (rotational cam operated legs)
  • Ground effect air cushions (hovercrafts)
  • Jumping and hopping
  • Flying (airfoil using, helium balloons, multirotors, etc.)

Robot control requirements:

  • Tele-operated robots must be radio controlled, or use an approved custom system. Radio controlled robots must use approved ground frequencies including 27/49/50/53/75/900/2400 for the United States or 2.4Ghz.
  • Any robot with an active weapon must use 2.4Ghz radio systems.
  • Tethered control is not allowed.
  • Pre 1991 non-narrow band radio systems are not allowed.
  • Radio systems with fail-safe protection that stops all motion in the robot (drive and weapons), when the transmitter loses power or signal, are required for all robots with active weapons and recommended for those without active weapons. This may be inherent in the robots electrical system or be part of programmed fail-safes in the radio. A weapon is considered “active” if it is powered by a source other than the drive system.
  • All robot radio systems must have a way to change frequencies or coded channels to prevent radio conflicts. Having at least two frequencies or coded channels available is required . Lack of extra frequencies may result in a forfeit. Digital spread-spectrum radios that use frequency hopping or automatic channel selection qualify under this rule.
  • If you are using a home built control system, or a control system not covered here, you must first clear it with this event.
  • Toy radio systems are allowed at this event for robots with no active weapons.
  • RC systems on the AM band are allowed at this event for robots with no active weapons.
  • This event does not require a separate power switch for the radio, but it is encouraged.
  • This event reserved frequencies/channels for testing and safety.
  • The event organizers will not be responsible for mitigating any interference issues encountered due to the arena design. We encourage all builders to extensively test their system before the event and make sure it will work reliably inside the combat arena.

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: Alkalines, NiCads, NiMh, dry cells, AGM, LIon, LiPoly, etc. If your design uses a new type of battery, or one you are not sure about please contact this event .
  • All onboard voltages above 22 Volts (6 cell Lithium pack) 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 (Hella, Wyachi, FingerTech, 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 which could lead to a battery fire.
  • If your robot uses a grounded chassis you must have a switch capable of disconnecting this ground.
  • All robots with active weapons must have a light easily visible from the outside of the robot that shows its main power is activated. This is also highly recommended but not required for weapon-less robots.
  • If the robot’s battery becomes exposed during the match, event organizers reserve the right to declare the robot incapacitated and end the match scoring a victory for their opponent. This rule is intended to avoid the possibility of fires due to battery damage.

Rotational weapons or full body spinning robots:

  • Spinning weapons that can contact the outer arena walls during normal operation must be pre-approved by the event. (Contact with an inner arena curb, or containment wall is allowed and does not require prior permission. Inner barrier walls are approximately 6in tall and the outer wall is 1.5in behind the barrier)
  • Spinning weapons must come to a full stop within 60 seconds of the power being removed using a self-contained braking system.

Forbidden Weapons and Materials.

The following weapons and materials are absolutely forbidden from use:

  • Weapons that cause excessive damage to the arena during normal operation such as spinning weapons with insufficient ground clearance.
  • 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.
  • Weapons or defenses that stop combat completely of both (or more) robots. This includes nets, tapes, strings, and other entanglement devices.
  • 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
    • Inks and other marking materials
  • Heat and fire are forbidden as weapons. This includes, but is not limited to the following:
    • Heat or fire weapons
    • 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. (You are allowed to physically engulf your opponent with your robot however.) This includes, but is not limited to the following:
    • Smoke weapons
    • Lights such as external lasers above ‘ class I’ and bright strobe lights which may blind the opponent.
  • 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 this event if you have a question .