Robot combat

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Robot Combat is a hobby 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 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 competition FIRST.

Tombstone is launched by Megabyte at Combots

1 Weight Classes
2 Combat Robot Weaponry and Design
3 Prohibited weaponry
4 Unusual Weaponry
5 Unusual Propulsion
6 References
7 Images
8 Building a Combat Robot
9 See also
10 External links

[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
3 pound (1.36 kg) - Beetleweight
6 pound (2.72 kg) - Mantisweight
12 pound (5.44 kg) - Hobbyweight
15 pound BBIQ weightclass
30 pound (14 kg) - Featherweight
60 pound (27 kg) - Lightweight
120 pound (54 kg) - Middleweight
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. Plus, tiny robots look awfully out of place and are hard to see in a giant arena. 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, unteathered 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, and the United Kingdom.

[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 is 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 (shell spinner/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.

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 has been only one successful crushing combat robot: two-time Robot Wars world champion Razer.

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]. Although UK Robot Wars competitor Cassius is credited with the first demonstration of a SRiMech in competition at the Second Wars (1998), the 1996 US Robot Wars champion Biohazard was capable of self-righting via its highly extensible lifting arm (Biohazard's self-righting ability was lost when the hinged side skirts were added in 1997).

[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

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.

[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 middleweight 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 who around the arena.
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.
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.
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 and have no particular advantage. 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 “Sufflebot” 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.
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 uses almost exclusively in three-pound and under “insect class” robots, but the heavyweight Robotica competitor Hot Wheels attempted to use a large chassis-mounted magnet to gain traction and apparent weight.
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.
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 paper-maché 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 which competed as a superheavyweight at the 2000 Las Vegas Battlebots tournament used a series of actuators to bend it's tubular body and roll across the arena.