Robot combat

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Not to be confused with Military robots.

Robot Combat is a hobby/sport in which two or more radio-controlled machines use varied methods of destroying or disabling the other robot. The machines are referred to as robots, though some will argue that they are not 'robots' as they are not autonomous. Robot Combat enjoyed a period in the public eye when several television shows broadcast the robot fights. Either the public or the TV network administrators lost interest, and the shows dropped from the airwaves. The most well-known of these shows were Battlebots, Robot Wars, and Robotica. Combat robots have received mention in the press and entertainment shows from time to time as well.

Robot builders may be of any age and come from any walk of life. The robots themselves can range from modified remote controlled toys weighing less than a pound to three-hundred plus pounds of exotic metallurgy and sophisticated electronics. Although building a combat robot can cost thousands of dollars and hundreds of hours, some schools use the construction of combat robots in their courses to teach mechanical design and technology. For schools that shy away from the violence of combat robots, there are robotic competition alternatives such as the cooperative competitions FIRST and BEST Robotics.


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[edit] Weight classes

Robots come in all shapes and sizes, but there are certain defining lines that robots rarely stray across, thanks to official rules and practicality. The standard by which all combat robots are measured is weight; the everyday dilemma of the robot builder is to cram as much power into as little weight as possible. Robots can be as small as the 75 gram 'Fleaweight' class, and as large as the 340-pound 'Super Heavyweight' class. The common weightclasses are as follows:

  • 75g- Fleaweight
  • 150g- Fairyweight (UK - Antweight)
  • 1 pound (454 g) - Antweight
  • 1 kilogram (2.2 lbs) Kilobot (Canada)
  • 3 pound (1.36 kg) - Beetleweight
  • 6 pound (2.72 kg) - Mantisweight
  • 12 pound (5.44 kg) - Hobbyweight
  • 15 pound (6.80 kg) - BotsIQ Mini class
  • 30 pound (14 kg) - Featherweight
  • 60 pound (27 kg) - Lightweight
  • 120 pound (54 kg) - Middleweight / BotsIQ Large class
  • 220 pound (100 kg) - Heavyweight
  • 340 pound (154 kg) Super Heavyweight

There are some international variations in weight class - for example, UK robot builders define the Antweight class limit as 150g and the Featherweight class limit as 12kg (26 pounds).

Weight is a precious asset for robot builders. For the sake of diversity of design, the rules often give an extra weight allotment for robots that can walk rather than roll on wheels. Such robots are more difficult to construct and their drive mechanisms are heavier. Some builders opt to build walking robots, taking advantage of the extra weight to add more powerful weaponry at the expense of greater complexity and fragility.

Given the violent nature of robot fighting, safety is always the most important issue at robot events. Robot fights take place in a sturdy arena, usually constructed of steel, wood, and bulletproof clear Lexan plastic. The size of the arena varies by the weightclass of the robots that are fighting in it. Some large competitions that entertain many different weightclasses have more than one arena, because 1 pound antweights don't need 50 foot (15 m) wide arenas in which to fight, but 220 pound heavyweights do. Having multiple arenas allows the event to progress more quickly.

Competition rules set limits on construction features that are too dangerous or which could lead to uninteresting contests. Strict limits are placed on materials and pressures used in pneumatic or hydraulic actuators, and fail-safe systems are required for electronic control circuits. Generally off-limits for use as weapons are nets, liquid, radio jamming, high-voltage electric discharge, untethered projectiles, and usually fire.

The Robot Fighting League (RFL) was created in 2002 when several builders decided that robot combat needed standardization of rules and judging criteria. The majority of robot combat events in the U.S. have become RFL members and have adopted their ruleset, but some event organizers oppose the direction in which the RFL is taking the sport and remain independent. The topic of event standardization has lent itself to a healthy amount of controversy since the RFL's inception.

The sport continues today despite the lack of television coverage. The size of the events has diminished, but there are scores of tournaments scattered throughout the United States, Canada, United Kingdom and Iran.

[edit] Combat robot weaponry and design

An effective combat robot must have some method of damaging or controlling the actions of its opponent while at the same time protecting itself from aggression. The tactics employed by combat robot operators and the robot designs which support those tactics are numerous. Although some robots have multiple weapons, the more successful competitors concentrate on a single form of attack.

  • Rammer - Robots employing high-power drive trains and heavy armor are able to use their speed and maneuverability to crash into their opponent repeatedly with hope of damaging weapons and vital components. Their pushing power may also be used to shove their opponent into arena hazards. Rammers (AKA ‘Bricks’) typically have four or six wheels for traction and stability and are often designed to be fully operational when inverted. Robot Wars champion Tornado was an effective rammer.
  • Wedge - Similar in concept to a rammer, the wedge uses a low-clearance inclined wedge or scoop to move in under an opponent and break its contact with the arena floor – decreasing its mobility and rendering it easy to push off into a wall or hazard. The wedge is also useful in deflecting attacks by other robots. Wedges are also used to lift an opponent up to make the attack of another weapon more effective. A small wedge may be attached to the rear of a robot with other weaponry for use as a ‘backup’ in case the main weapon fails. The 1995 US Robot Wars middleweight champion La Machine was an early and effective wedge design.
  • Spinner - Continuously rotating weapons are popular and varied. These use a dedicated motor to spin up a heavy bar, studded disc, or toothed cylinder (drum/eggbeater) and use it to strike the opponent with the kinetic energy stored in the rotating mass. The mass may spin on either a horizontal or vertical axis, although vertical spinners may have maneuverability problems due to the gyroscopic action of the weapon. The destructive potential of a well designed spinning weapon requires robust arena containment to prevent shrapnel being thrown into the audience. Three-time BattleBots middleweight champion Hazard was a horizontal bar spinner.
  • Full Body Spinner - Taking the concept of the spinner to the extreme, a full body spinner (AKA shell spinner or tuna can spinner) rotates the entire outer shell of the robot as a stored energy weapon. Other robot components (batteries, weapon motor casing) may be attached to the shell to increase the spinning mass while keeping the mass of the drive train to a minimum. An FBS robot takes several seconds to spin the heavy shell up to effective speed, and they must evade their opponent while waiting for that speed. The 1995 US Robot Wars heavyweight co-champion Blendo was the first effective full body spinner.
  • Thwackbot - A narrow, high-speed, two-wheel drive train attached to a long boom with an impact weapon on the end creates a robot that can spin in place at a high speed, swinging the weapon in a horizontal circle. The simplicity and durability of the design is appealing, but the robot cannot be made to move in a controlled manner while spinning without employing sophisticated electronics. The 1995 US Robot Wars lightweight champion Test Toaster 1 was a thwackbot, as were T-Wrex and Golddigger from the BattleBots series.
  • Torque Reaction - A variant on the thwackbot is the torque reaction hammer. These robots have two very large wheels with the small body of the robot hanging in between them. A long weapon boom has a vertically oriented hammer, pick, or axe on the end. On acceleration, the weapon boom swings upward and over to the rear of the robot to offset the motor torque. When the robot reverses direction, the weapon will swing forcibly back over the top and hopefully impact the opponent. These robots are simple and can put on a flashy, aggressive show, but their attack power is relatively small. BattleBots 2.0 middleweight champion Spaz was a torque reaction pickaxe robot.
  • Lifter - Using tactics similar to a wedge, the lifter uses a powered arm, prow, or platform to get underneath the opponent and lift it away from the arena surface to remove its maneuverability. The lifter may then push the other robot toward arena hazards or attempt to toss the opponent onto its back. The lifter is typically powered by either an electric or pneumatic actuator. Two-time US Robot wars and four-time BattleBots heavyweight champion Biohazard was an electric lifter.
  • Flipper - Although mechanically resembling a lifter, the flipper uses much higher levels of pneumatic power to fire the lifting arm explosively upward. An effective flipper can throw opponents end-over-end thru the air causing damage from the landing impact or, at Robot Wars, toss it completely out of the arena. Flippers use a large volume of compressed gas and may have a limited number of effective attacks before their supply runs low. The two-time Robot Wars champion Chaos 2 and BattleBots super heavyweight champion Toro were flippers.
  • Clamper - Another lifter variant, the clamper adds an arm or claw that descends from above to secure the opposing robot in place on a lifting platform. The entire assembly then lifts and carries the opponent wherever the operator pleases. Two-time BattleBots super heavyweight champion Diesector was an electric clamper.
  • Dustpan - An uncommon variant on the clamper, the dustpan simplifies the design by replacing the lifting platform with a wide box open at the front and top. An opponent maneuvered into the box may then be restrained with an arm or claw from above. Some designs use only the box with no restraining claw.
  • Crusher - Related to the dustpan, the crusher uses a hydraulic cylinder attached to a sharp piercing arm to pin and penetrate the usually weak top armor of the opponent. Enormous strength and careful engineering is required to build an effective crusher, which may be why there have been only two successful crushing combat robots: two-time Robot Wars world champion Razer and two-time Robot Wars Annihilator champion Kan-Opener.
  • Overhead Axe - Swinging an axe, spike, or hammer down onto your opponent offers another method of attacking the vulnerable top surface. The weapon is typically driven by a pneumatic actuator via a rack and pinion or direct mechanical linkage. The attack may damage the opposing robot directly, or may lodge in their robot and provide a handle for dragging them toward a hazard. BattleBots heavyweight runner-up and Robot Wars competitor Killerhurtz was armed with an overhead axe.
  • SRiMech - Some robot and weapon designs are not compatible with inverted operation. A Self Righting Mechanism is an active design element that returns an inverted robot to mobility in the upright state. The SRiMech is typically an electric or pneumatic arm or extension on the upper surface of the robot which pushes against the arena floor to roll or flip the robot upright. Some carefully designed flipping or lifting weapons can perform double-duty as SRiMechs. Even a vertical spinning weapon may be used as a crude self-righting device. Team Nightmare's lightweight vertical spinner Backlash was designed such that when flipped it would hit the ground with the spinning disc and kick back upright.[1] The first successful unaided use of a SRiMech in competition was at the 1997 U.S. Robot Wars when the immobilized Vlad the Impaler used a dedicated pneumatic device to pop back upright in a match against Biohazard.

[edit] Prohibited weaponry

Since the first robot combat competitions, some types of weapons have been prohibited either because they violated the spirit of the competition or they could not be safely used. Prohibited weapons have generally included:

  • Radio jamming
  • High voltage electric discharge
  • Liquids (glue, oil, water, corrosives…)
  • Open combustion (fire, explosives…)
  • Un-tethered projectiles
  • Lasers above 1 milliwatt
  • Visual obstruction
  • Halon - a specific fire extinguishing gas effective as a weapon in stopping internal combustion engines. Note that current rules do not specifically ban Halon as it is no longer commercially available.

Individual competitions have made exceptions to the above list. Notably, the Robotica competitions allowed flame weapons and the release of limited quantities of liquids on a case-by-case basis.

Arena hazards have also been granted exceptions to the list of prohibited weapons. Robot Wars in particular used flame devices both in the stationary hazards and on some of the roaming "House Bots".

[edit] Unusual weaponry

A very wide variety of unusual weapons and special design approaches have been tried with varying success and several types of weapons would have been tried had they not been prohibited.

  • Entanglement Weapons - Several early US Robot Wars competitors sought to immobilize their opponents with entangling weapons. Nets and streamers of adhesive tape were both tried with mixed success. Entangling weapons were prohibited in Robot Wars and BattleBots from 1997 onward, but the Robotica competitions allowed nets, magnets, and other entangling devices on a case-by-case basis.
  • Flame Weapons - Although prohibited in Robot Wars and BattleBots, Robotica and current Robot Fighting League rules allow flame weapons under some circumstances. RFL super heavyweight competitor Alcoholic Stepfather and Robotica competitor Solar Flare employed gaseous flamethrower weapons. Flamethrowers are not effective weapons, but are audience favorites.
  • Smothering Weapons – The BattleBots and Robot Wars lightweight competitor Tentoumushi used a large plastic sandbox cover on a powered arm to drop down over opposing robots, covering and encircling them. Once covered, it was difficult to tell what the opponent was doing and who was dragging whom around the arena. One version of the robot had a circular saw concealed under the cover to inflict physical damage.
  • Tethered Projectiles – Although tethered projectiles are specifically allowed and discussed in major rules sets, their use is quite rare. Neptune fought at BattleBots 3.0 with pneumatic spears on tethers, but was unable to damage their opponent. During a friendly weapons test, Team Juggerbot allowed the builders of Neptune to use their weapon against their bot. The result was the tethered spears being able to puncture good sized holes in thick armour.
  • Multibots (clusterbots) – A single robot that breaks apart into multiple, independently controlled robots has appealed to a few competitors. The Robot Wars heavyweight Gemini and the BattleBots middleweight Pack Raptors were two-part multibots that had some success. The rules concerning clusterbots have varied over the years, either stating that 50% of the clusterbot has to be immobilised to eliminate the robot from the tournament, or that all of a multibot's segments have to be incapacitated before a knock-out victory can be declared. Current Robot Fighting League match rules[2] require the latter to be achieved.
  • Halon Gas – Rhino Halon fought at the 1997 U.S. Robot Wars event with a halon gas fire extinguisher, which was very effective at stopping internal combustion engines. Gas weapons of this nature were promptly prohibited from future competitions.

[edit] Unusual propulsion

The great majority of combat robots roll on wheels, which are very effective on the smooth surfaces used for typical robot combat competition. Other propulsion strategies do pop-up with some frequency.

  • Tank Treads – Numerous combat robots have used treads or belts in place of wheels in an attempt to gain additional traction. Treads are generally heavier and more vulnerable to damage than a wheeled system, offer no particular mechanical advantage, and as such are mostly used for their striking appearance. The RobotWars competitor 101 and the BattleBots super heavyweight Ronin used treads.
  • Walking – The spectacle of a multi-legged robot walking across the arena into combat is a big audience favorite. Robot combat rules typically have given walking robots an additional weight allowance to encourage their construction. What the event organizers had in mind was something like the spider-legged robot Mechadon, but what most often was produced were simple rule-shaving propulsion systems that attempted to save as much of the extra weight allowance as possible for additional weaponry. Attempts at more restrictive definitions of “Walking” have effectively eliminated walking robots from competition. BattleBots heavyweight champion Son of Whyachi used a controversial cam-driven “Shufflebot” propulsion system, which was promptly declared ineligible for additional weight allowance at subsequent competitions.
  • Suction Fan – Several competitors experimented with the use of fans to evacuate air from a low-clearance shell to suck the robot down onto the arena surface and add traction. Robotica competitor Armorgeddon used a suction fan to increase traction and pushing power, and Robot Wars UK robot TerrorHurtz used a suction fan to counter the forces from its hammer/axe weapon. Similar designs have appeared in robot-sumo competitions where traction is a key factor.
  • Magnet Wheels – Another approach to gaining traction and stability involves the use of ring-shaped rare-earth magnets as wheels. This is, naturally, only effective in arenas which have magnetic metal surfaces. Due to the expense of large ring magnets, this trick has been used almost exclusively in three-pound and under “insect class” robots, although a lightweight battlebot General Gau tried implementing them. Heavyweight Robotica competitor Hot Wheels attempted to use a large chassis-mounted magnet to gain traction and apparent weight, and Beta Hurtz unsuccessfully attempted to use an electromagnet to counter the reaction forces of its massive hammer weapon at the BattleBots competition. The result ended in the robot being completely stuck to the floor.
  • Mecanum Wheels – The previously mentioned RFL super-heavyweight competitor Alcoholic Stepfather uses Mecanum wheels and specialized motor control systems that allow it controlled motion in any direction without turning. This is eerie to watch, and disruptive of attack and defense maneuvers by opponents. Root Canal implemented a similar design at BattleBots using Omni wheels angled at 45 degrees.
  • Translational Drift - Also known as Melty Brain or Tornado Drive, this sophisticated system supplements the twackbot drivetrain with electronic rotation sensors and rapid speed controller switching that allows a rotating twackbot to move in a controlled manner while spinning. Several robots have implemented this complex design, but none with particular success. Herr Gerpunden, a lightweight robot, has shown successful use of the Tornado Drive and has used it successfully in smaller competitions. The drive is implemented with an LED light system that tells the driver it's current position, indicating where the robot should be driven to.
  • Flying – The 1995 US Robot Wars event had a flying competitor: S.P.S. #2 was a lighter-than-air craft buoyed by three weather balloons and propelled by small electric fans. It attempted to drop a net on the opponent. Nearly invulnerable to attack, it won the first match against Orb of Doom (see reference below), but ventured too close to the arena floor in the second match and was dragged down and "popped".
  • Rolling Sphere – The afore-mentioned Orb of Doom was a featherweight competitor at the 1995 US Robot Wars. It consisted of a remote-controlled toy car inside a hollow papier-mâché sphere. It was able to roll around the arena in a controlled manner, but was incapable of effective offense. A similar robot named Psychosprout appeared in the UK Robot Wars.
  • Rolling Tube -Snake competed at Battlebots and the US Robot Wars using a series of actuators to bend its triangular cross-section tubular body to roll, writhe, and slither across the arena.
  • Shuffling - refers to the movement of robots that are propelled by a cam-driven system. See Walking

[edit] References

  1. ^ RobotCombat.com Robot Combat History - San Francisco 2001
  2. ^ http://www.botleague.net/doc/rfl-match-rules-0-03.pdf

[edit] See also

[edit] External links

[edit] Combat robot parts suppliers

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