Robot combat

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Chaos 2, a combatant robot from the Robot Wars TV series. Its weapon is a CO₂-powered pneumatic flipper

 

Robot combat is a form of robot competition in which two or more custom-built machines use varied methods of destroying or disabling the other. The machines are generally remote-controlled vehicles rather than autonomous robots, though not exclusively. 

Robot combat competitions have been made into television series, including Battlebots in the US and Robot Wars in the UK. These shows were originally broadcast in the late 1990s to early 2000s and experienced revivals in the mid-2010s. As well as televised competitions, smaller robot combat events are staged for live audiences such as those organised by the Robot Fighting League. 

Robot builders are generally hobbyists and the complexity and cost of their machines can vary substantially. Robot combat uses weight classes, with the heaviest robots able to exert more power and destructive capabilities. The rules of competitions are designed for safety of the builders, operators, and spectators while also providing for an entertaining spectacle. Robot combat arenas are generally surrounded by a bulletproof screen. 

Competitor robots come in a variety of designs, with different strategies for winning fights. Robot designs typically incorporate weapons for attacking opponents, such as axes, hammers, flippers and spinning devices. Rules almost always prohibit gun-like weapons as well as other strategies not conducive to the safety and enjoyment of participants and spectators.

History

Critter Crunch in 1991, at the moment when "Agent Orange" beat Bill Lewellyn's critter to win the event.

 

Among the oldest robotic combat competitions extant in the United States are the "Critter Crunch" (founded about 1987) in Denver and "Robot Battles" (founded in 1991) based in the southeastern U.S. Both events are run by members of the "Denver Mad Scientists Society".

• 1987 - The "Denver Mad Scientists Society" organized the first Critter Crunch competition at Denver's MileHiCon science-fiction convention.
• 1991 - Kelly Lockhart organized the first "Robot Battles" competition at Atlanta's DragonCon science-fiction convention.
• 1994 - Marc Thorpe organized the first Robot Wars competition in San Francisco. Four annual competitions were held.
• 1997 - Rights to the Robot Wars name is transferred to British TV production company who produce the Robot Wars television series. Early seasons feature competitive games and obstacle courses as well as simple combat. The series aired 151 episodes across 12 series from 1997 to 2003. Special series were produced for the United States and the Netherlands.
• 1999 - Former Robot Wars competitors in the U.S. organize a new competition named BattleBots. The first tournament was shown as a webcast, with the second tournament shown as a cable 'Pay-per-view' event.
• 2000 - BattleBots is picked up as a weekly television program on Comedy Central. It would span five seasons ending in 2002.
• 2001 - Robotica appears on The Learning Channel as a weekly series. The format features tests of power, speed and maneuverability as well as combat. The show ran in three series, ending in 2002.
• 2002 - Foundation of the Robot Fighting League, a regulatory body composed of the organizers of robot combat events in the United States, Canada, and Brazil. The body produces a unified set of regulations and promotes the sport.
• 2004 - Robot Combat is included as an event at the ROBOlympics in San Francisco, California, with competitors from multiple countries.
• 2008 - ROBOlympics changes its name to RoboGames and, while most events are not combat related, Robot Combat is significantly featured.
• 2015 - BattleBots returns to television as a summer series on the ABC television network; it would be renewed for a second season which aired in the summer of 2016.
• 2016 - Robot Wars returns to British television on BBC2, with two further series in 2017 and 2018.
• 2018 - BattleBots returns to television after a year hiatus on the Discovery Channel and The Science Channel. King of Bots, Fighting my Bot, This Is Fighting Robots and Clash Bots are held and broadcast in China.

Rules

Robot combat involves remotely controlled robots fighting in a purpose-built arena. A robot loses when it is immobilized, which may be due to damage inflicted from the other robot, being pushed into a position where it cannot drive (though indefinate holds or pins are typically not permitted), or being removed from the arena. Fights typically have a time limit, after which, if no robot is victorious, a judge or judges evaluates the performances to decide upon a winner.

Weight classes

Combat robots in the pit area at the 2007 Robot Battles competition in Atlanta, Georgia.

 

Similar to human combat sports, robot combat is conducted in weight classes though with maximum limits even in the heaviest class. Heavier robots are able to exert more power and have stronger armour, and are generally more difficult and expensive to build. 

Class definitions vary between competitions. The below table shows classifications for two organizations: the UK-based Fighting Robots Association (FRA) and the North American SPARC. 

Maximum weight per class

Class	FRA	SPARC
Fairyweight	N/A	0.15 kg (0.33 lb)
Antweight	0.15 kg (0.33 lb)	1 lb (0.45 kg)
Beetleweight	1.5 kg (3.3 lb)	3 lb (1.4 kg)
Mantisweight	N/A	6 lb (2.7 kg)
Hobbyweight	N/A	12 lb (5.4 kg)
Dogeweight	N/A	15 lb (6.8 kg)
Featherweight	13.6 kg (30 lb)	30 lb (14 kg)
Lightweight	30 kg (66 lb)	60 lb (27 kg)
Middleweight	55 kg (121 lb)	120 lb (54 kg)
Heavyweight	110 kg (240 lb)	220 lb (100 kg)
Alternative Heavyweight Class	N/A	250 lb (110 kg)

Most televised events are of heavyweights. Currently Battlebots has a weight limit of 250 lb (113 kg). To encourage diversity of design, rules often give an extra weight allotment for robots that can walk rather than roll on wheels.

Safety precautions

The Robot Wars arena

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 smaller, lighter classes compete in smaller arenas than the heavyweights.

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, liquids, deliberate radio jamming, high-voltage electric discharge, untethered projectiles, and usually fire.

Robot fighting associations

The sport has no overall governing body, though some regional associations oversee several events in managerial or advisory capacities with published rulesets. These include:

• Robot Fighting League (RFL), primarily U.S.. Operated 2002—2012.
• Fighting Robot Association (FRA), U.K., 2003–
• Standardised Procedures for the Advancement of Robot Combat (SPARC), U.S., 2015

The major televised competitions have operated outside of these associations.

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. This is a list of most of the basic types of weapons. Most robot weaponry falls into one of the following categories:

• 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. Because modern rulesets require all robots to have a moving weapon, modern rammers are equipped with other weapon types. Robot Wars Series 6 champion Tornado and Series 7 runner-up Storm II were effective rammers.
• 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. Like rammers, modern wedges must be combined with some other weapon in order to be legal. The 1995 US Robot Wars middleweight champion La Machine was an early and effective wedge design as was Robot Wars Series 1 champion, Roadblock (1997), and the deceptively simple 2018 BattleBots competitor DUCK!
• Saw Blades - A popular weapon in the early years of robotic combat, these robots use a dedicated motor to power either a modified chainsaw or circular saw, or a custom-built cutting disc, usually at high speeds (up to 10,000 RPM). The serrated blade is used to slice through an opponent's armour to try and reach its internal components. These weapons can create spectacular showers of sparks, and are easy to combine with other designs, but can be ineffective against robots with tougher armour. The aforementioned Robot Wars champion Roadblock had a rear-mounted circular saw in addition to its wedge, while Series 4 runner-up Pussycat had a custom cutting disc with four serrated blades.

Robot Wars competitor Aftershock uses a vertical spinning flywheel to attack opponents

• Spinner - Spinners are generally larger and heavier than saw blades, and spin at a lower RPM. Rather than cutting through the opponent, spinners use a heavy bar, studded disc, or toothed cylinder (drum/eggbeater) 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, while Robot Wars Series 3 runner-up Hypno-Disc was a flywheel spinner. As an alternative to the vertical-axis "full-body spinner" in destructive capability; the horizontal-axis drum spinner, exemplified by the 2017 and 2018 BattleBots-fielded Brazilian entry Minotaur, can easily spin its up-to 35 kg (77 lb) lobed drum at upwards of over 10,000 rpm., at times literally "launching" a vulnerable component of an opponent skywards with considerable force.
• 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. Full body spinners require time to spin the weapon up to speed, typically cannot self-right, and can be unstable — the original (2000-2005) BattleBots competitor Mauler being an infamous example, with the more recently fielded Captain Shrederator (which competed in all three ABC/Discovery/Science Channel 2010s seasons) having somewhat more success. The 1995 US Robot Wars heavyweight co-champion Blendo was the first effective full body spinner. A variant, the ring spinner, features a narrower spinning ring surrounding the robot; these designs have the advantage of being invertible. BattleBots 2016 competitor The Ringmaster is an example of a ring-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, also known as axlebots. 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 and, like thwackbots, they can be hard to control. BattleBots 2.0 middleweight champion Spaz was a torque reaction pickaxe robot, whilst Robot Wars Grand Finalist Stinger opted for a disc, later replaced with a bludgeoning mace.
• 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.

Robot Wars competitor Apollo, armed with a flipping weapon

• Flipper - Although mechanically resembling a lifter, the flipper uses much higher levels of pneumatic power to fire the lifting arm or panel explosively upward. An effective flipper can throw opponents end-over-end through the air causing damage from the landing impact or, in Robot Wars, toss it completely out of the arena. Flippers use a large volume of compressed gas and often have a limited number of effective attacks before their supply runs low. The two-time Robot Wars champion Chaos 2 and original, 2000s-era BattleBots superheavyweight champion Toro and middleweight competitor T-Minus were flippers, as is the same Team Inertia's more recent heavyweight robot Bronco, with both T-Minus and Bronco capable of self-righting with their powerful pneumatic flippers. While most flippers operate with the pneumatic arm hinged at the machine's rear, Robot Wars' Firestorm achieved remarkable success with a front-hinged flipper, placing third in Robot Wars on three separate occasions (Series 3, 5, and 6) and never failing to advance to the series' semifinal rounds.
• Stabber - Mechanically similar to the flipper is the stabber, which throws or stabs opponents forward instead of upward. An effective stabber can penetrate into the opponent, damage vital inner parts. When they fail to penetrate, they throw their opponent back across the arena into walls or hazards. Stabbers typically use a large volume of compressed gas, which limits the number of times they can fire their weapon in a fight. BattleBots super heavyweight Rammstein was a stabber.
• 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. BattleBots middleweight runner-up S.O.B. used a dustpan in conjunction with a sawblade mounted on an arm, with the more recent 2018 BattleBots competitor SawBlaze using a 180º pivoted-arm-mounted circular saw on their trident-style dustpan design to cut downwards into an opponent.
• Crusher - Like flywheels, crushers can be separated into horizontal and vertical variants. Vertical crushers use a hydraulic cylinder attached to a sharp piercing arm to pin and slowly penetrate the top armor of the opponent. Robot Wars Series 5 Champion and two-time world champion Razer was the first vertical crusher, and by far the most successful. Horizontal crushers feature two of these arms, which act like pincers to crush robots between them. Two-time Robot Wars Annihilator champion Kan-Opener is one example of a successful horizontal crusher.
• Overhead Axe - Swinging a high-speed axe, spike, or hammer forcefully 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. Some axes are double-sided, and can strike opponents both in front of and behind the robot; Killerhurtz' successor Terrorhurtz, and Robot Wars Series 2 Grand Finalist Killertron, were examples of this. The heavyweight pneumatically powered, bifurcated-armed pickaxe of Chomp from the 2016 and 2018 Battlebots competitions also incorporated short metal "wing" levers at the pickaxe-arms' rear ends to upright its bulky chassis if knocked onto its side during combat, and pioneered a hardware design that autonomously turned Chomp to always face its opponent during a match.
• SRiMech - Many robots are incapable of running inverted, due to their shape, weaponry, or both. A SRiMech (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. Most flippers, some lifters, and even some carefully designed axes can double 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. 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.

Many modern rulesets, such as the rebooted versions of BattleBots and Robot Wars, require robots to have an active weapon in order to improve the visual spectacle, thus eliminating certain designs such as torque-reaction axlebots and thwackbots, and requiring other designs such as wedges and rammers to incorporate some other kind of weapon.

Interchangeable weaponry

It is increasingly common for robots to have interchangeable weaponry or other modular components, allowing them to adapt to a wide range of opponents and increasing their versatility; such robots are often referred to as "Swiss army bots", in reference to Swiss army knives. Arguably the earliest example was Robot Wars Series 1 contestant Plunderbird, which could change between a pneumatic spike and a circular saw on an extendable arm. Successful Swiss army bots include Robot Wars Series 6 champion Tornado, BattleBots 2016 runner-up Bombshell, and top-ranked US Beetleweight Silent Spring. 

Sometimes, robots that were not originally Swiss army bots have had their weapons changed or altered on the fly, typically due to malfunctions. In BattleBots 2015, Ghost Raptor's spinning bar weapon broke in its first fight; builder Chuck Pitzer then improvised new weapons for each following fight, including a "De-Icer" arm attachment which it used to unbalance and defeat bar spinner Icewave in the quarter-finals.

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…)
• Fire (except in BattleBots)
• Explosives
• Un-tethered projectiles
• Entanglement devices (except in Robot Wars from series 10 onwards)
• 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.^[22] The modern series of BattleBots also permits the use of flamethrowers and, as of 2016, untethered projectiles, provided that the latter are merely for show. Competitions may also restrict or ban certain otherwise legal weapons, such as banning spinners and other high-power weapons at events where the arena is not able to contain these weapons. A well-known example of this is the Sportsman ruleset. 

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 one of the roaming "House Robots".

Unusual weaponry

A robot housed in a dog house uses flame against a full body spinner opponent.

 

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, and Robot Wars is set to allow limited use of entanglement devices from Series 10 onwards. The sixth season of BattleBots in 2015 failed to explicitly exclude entanglement devices, which resulted in at least one controversial decision.
• Flame weapons - Although prohibited for use by competitors in Robot Wars and the first edition (2000-05) of BattleBots, the rules for Robotica, the Robot Fighting League and the post-2015 version of BattleBots do allow flame weapons under some circumstances. RFL super heavyweight competitor Alcoholic Stepfather (unique for using mecanum wheels for movement around an arena) and Robotica competitor Solar Flare, as well as the later BattleBots series competitors Free Shipping and overhead pneumatic-pickaxe armed Chomp employing gaseous flamethrower weapons. Flamethrowers are seldom effective weapons, but are audience favorites.
• Smothering weapons – The BattleBots and Robot Wars lightweight competitor Tentoumushi used a large plastic sandbox cover shaped like a ladybug ("tentoumushi" being Japanese for ladybug) 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, another had a small grappling hook.
• 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 its opponent. During a friendly weapons test, Team Juggerbot allowed the builders of Neptune to take a couple shots against their bot. One of two shots penetrated an aluminum panel below the main armor, while the other bounced off the top armor.
• 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 (in the Dutch version of Robot Wars, there was a 3-part multibot named √3, and although one of its parts was tossed out of the arena by Matilda, the robot as a whole was still deemed mobile, and the other 2 parts of √3 did enough to win the match), 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 require the latter to be achieved.
• Minibots (nuisancebots) - Similar to the concept of multibots, minibots are small robots, typically no larger than a featherweight, that fight alongside a larger main robot with the aim of harassing or distracting opponents. They are often sacrificial in nature and have minimal weaponry. BattleBots 2015 competitor Witch Doctor was accompanied by a featherweight minibot named Shaman that was equipped with a flamethrower, and which gained significant popularity for its spirited performances during battles. Other Battlebots competitors also successfully used minibots such as Son of Whyachi in 2016, and 2018 fan favorite WAR Hawk and their beetleweight minibot WAR Stop, which was equipped with a wedge.
• Halon gas – Rhino 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.
• Air Cannon - First implemented by Season eight Battlebots competitor Double Jeopardy, the robot fired off a 5-pound "slug" at 190mph, exerting 4,500 pounds of force upon impact. This robot, however, did not perform well during its competition, as it only had one shot at landing a good hit: from there, it would have to rely on pushing its opponents, at which it failed.

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 offer no particular traction advantage on the types of surfaces common in robot combat. Most uses of treads are for their striking appearance. The Robot Wars competitors 101 and Mortis along with the BattleBots super heavyweight Ronin used treads. Biteforce, the winner of the 2015 Battlebots Competitions, used magnets embedded in its treads in an attempt to gain extra downforce without extra weight.
• 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 offset their slower speed, the complexity of the mechanism, and 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.
• Gyroscopic precession – Used in the Antweight robot Gyrobot, as well as the Battlebots competitor Wrecks, this system uses a gyroscope and stationary feet that lift as the entire robot rotates due to gyroscopic precession when the gyroscope is tilted by a servo motor. This design can use the gyroscope as a spinning weapon (horizontal or vertical) which allows for efficient double-usage of the gyroscope mass. Although Gyrobot and Wrecks appear to be walking as it translates across the arena, they're not classified as walking robots under current rules. This unusual drive train produces strange and often unpredictable movements, though has shown to be successful in combat.
• 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.
• Magnetic Wheels – Another approach to gaining traction and stability involves the use of rare-earth magnets, either ring-shaped as wheels or simply attached to the robot's base. 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. A multibot named Hammer and Anvil would later use magnets in the lightweight category, with some success. Heavyweight Robotica competitor Hot Wheels attempted to use a large chassis-mounted magnet to gain traction and apparent weight, and Beta unsuccessfully attempted to use an electromagnet to counter the reaction forces of its massive hammer weapon at the BattleBots competition. This resulted in the robot being completely stuck to the floor.
• Mecanum wheels – Together with a specialized motor control system, mecanum wheels allow controlled motion in any direction without turning, as demonstrated by Alcoholic Stepfather in a 2004 match.
• Translational drift - Also known as Melty Brain or Tornado Drive, this sophisticated system supplements the thwackbot drivetrain with electronic rotation sensors and rapid speed controller switching that allows a rotating thwackbot to move in a controlled manner while spinning. Several robots have implemented this complex design, but few with particular success. Herr Gepoünden, a lightweight robot, has shown successful use of the Tornado Drive and has used it successfully in smaller competitions. Additionally, Nuts 2 utilized this technology with tremendous effect on Robot Wars and managed to finish third overall in Series 10 in 2017. The drive is usually implemented with an LED light system that indicates to the driver the direction the robot will move when commanded to move forwards.
• 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". Starting in 2016, BattleBots permitted the use of quadcopter drones as "nuisance bots"; these typically proved hard to control, and one was memorably swatted out of the air by a rake that competitor HyperShock had attached to its lifting forks.
• Rolling sphere – The aforementioned Orb of Doom was a featherweight competitor at the 1995 US Robot Wars. It consisted of a lightweight, rigid shell made of carbon fiber-kevlar cloth and polyester resin, applied over a foam core pattern. Inside was an offset-weight mechanism made from a battery-powered electric drill. A similar looking 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
• Brush Drive - Similar to Gyroscopic precession, brush drive uses brushes affixed to the bottom of the robot. These work in tandem with a pair of vertical spinning weapons to make the robot slide across the arena.
• Magnets and Rapid Deceleration - While it has never been done, an entrant to Battlebots' seventh season, titled Bad Penny, had planned on using a magnetic system combined with a braking system to move their robot around the arena. Six magnets would pull down on the floor with over 2000 pounds (~909 kilograms) of force. To move, the robot would rely on rapidly braking its spinning ring, which was around the entire robot, while simultaneously turning off five of the six magnets. This, in turn, would force the robot to pivot around the one magnet still on.
• Hopping - Using pneumatic legs or spikes, robots such as the featherweight Spazhammer were capable of moving around the arena by repeatedly stabbing the floor.

Robot-sumo

Robot-sumo is a related sport where robots try to shove each other out of a ring rather than destroy or disable each other. Unlike remote-controlled combat robots, machines in these competitions are often automated.

NASA Deep Space Network

From Wikipedia, the free encyclopedia

Deep Space Network

Insignia for the Deep Space Network's 40th anniversary celebrations, 1998.
Alternative names	NASA Deep Space Network
Organization	Interplanetary Network Directorate (NASA / JPL)
Location	United States of America, Spain, Australia
Coordinates	34°12′3″N 118°10′18″WCoordinates: 34°12′3″N 118°10′18″W
Established	October 1, 1958
Website	https://deepspace.jpl.nasa.gov/
Telescopes
Goldstone Deep Space Communications Complex Barstow, California, United States Madrid Deep Space Communications Complex Robledo de Chavela, Community of Madrid, Spain Canberra Deep Space Communication Complex Canberra, Australia

The NASA Deep Space Network (DSN) is a worldwide network of U.S. spacecraft communication facilities, located in the United States (California), Spain (Madrid), and Australia (Canberra), that supports NASA's interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the Solar System and the universe, and supports selected Earth-orbiting missions. DSN is part of the NASA Jet Propulsion Laboratory (JPL). Similar networks are run by Russia, China, India, Japan and the European Space Agency.

General information

Deep Space Network Operations Center at JPL, Pasadena (California) in 1993.

 

DSN currently consists of three deep-space communications facilities placed approximately 120 degrees apart around the Earth. They are:

• the Goldstone Deep Space Communications Complex (35°25′36″N 116°53′24″W) outside Barstow, California. For details of Goldstone's contribution to the early days of space probe tracking, see Project Space Track;
• the Madrid Deep Space Communications Complex (40°25′53″N 4°14′53″W), 60 kilometres (37 mi) west of Madrid, Spain; and
• the Canberra Deep Space Communication Complex (CDSCC) in the Australian Capital Territory (35°24′05″S 148°58′54″E), 40 kilometres (25 mi) southwest of Canberra, Australia near the Tidbinbilla Nature Reserve.

Each facility is situated in semi-mountainous, bowl-shaped terrain to help shield against radio frequency interference. The strategic placement with nearly 120-degree separation permits constant observation of spacecraft as the Earth rotates, which helps to make the DSN the largest and most sensitive scientific telecommunications system in the world.

The DSN supports NASA's contribution to the scientific investigation of the Solar System: It provides a two-way communications link that guides and controls various NASA unmanned interplanetary space probes, and brings back the images and new scientific information these probes collect. All DSN antennas are steerable, high-gain, parabolic reflector antennas. The antennas and data delivery systems make it possible to:

• acquire telemetry data from spacecraft.
• transmit commands to spacecraft.
• upload software modifications to spacecraft.
• track spacecraft position and velocity.
• perform Very Long Baseline Interferometry observations.
• measure variations in radio waves for radio science experiments.
• gather science data.
• monitor and control the performance of the network.

Operations control center

The antennas at all three DSN Complexes communicate directly with the Deep Space Operations Center (also known as Deep Space Network operations control center) located at the JPL facilities in Pasadena, California. 

In the early years, the operations control center did not have a permanent facility. It was a provisional setup with numerous desks and phones installed in a large room near the computers used to calculate orbits. In July 1961, NASA started the construction of the permanent facility, Space Flight Operations Facility (SFOF). The facility was completed in October 1963 and dedicated on May 14, 1964. In the initial setup of the SFOF, there were 31 consoles, 100 closed-circuit television cameras, and more than 200 television displays to support Ranger 6 to Ranger 9 and Mariner 4.

Currently, the operations center personnel at SFOF monitor and direct operations, and oversee the quality of spacecraft telemetry and navigation data delivered to network users. In addition to the DSN complexes and the operations center, a ground communications facility provides communications that link the three complexes to the operations center at JPL, to space flight control centers in the United States and overseas, and to scientists around the world.

Deep space

View from the Earth's north pole, showing the field of view of the main DSN antenna locations. Once a mission gets more than 30,000 km from Earth, it is al­ways in view of at least one of the stations.

 

Tracking vehicles in deep space is quite different from tracking missions in low Earth orbit (LEO). Deep space missions are visible for long periods of time from a large portion of the Earth's surface, and so require few stations (the DSN has only three main sites). These few stations, however, require huge antennas, ultra-sensitive receivers, and powerful transmitters in order to transmit and receive over the vast distances involved. 

Deep space is defined in several different ways. According to a 1975 NASA report, the DSN was designed to communicate with "spacecraft traveling approximately 16,000 km (10,000 miles) from Earth to the farthest planets of the solar system." JPL diagrams state that at an altitude of 30,000 km, a spacecraft is always in the field of view of one of the tracking stations. 

The International Telecommunications Union, which sets aside various frequency bands for deep space and near Earth use, defines "deep space" to start at a distance of 2 million km from the Earth's surface.

This definition means that missions to the Moon, and the Earth–Sun Lagrangian points L₁ and L₂, are considered near space and cannot use the ITU's deep space bands. Other Lagrangian points may or may not be subject to this rule due to distance.

History

The forerunner of the DSN was established in January 1958, when JPL, then under contract to the U.S. Army, deployed portable radio tracking stations in Nigeria, Singapore, and California to receive telemetry and plot the orbit of the Army-launched Explorer 1, the first successful U.S. satellite. NASA was officially established on October 1, 1958, to consolidate the separately developing space-exploration programs of the US Army, US Navy, and US Air Force into one civilian organization.

On December 3, 1958, JPL was transferred from the US Army to NASA and given responsibility for the design and execution of lunar and planetary exploration programs using remotely controlled spacecraft. Shortly after the transfer, NASA established the concept of the Deep Space Network as a separately managed and operated communications system that would accommodate all deep space missions, thereby avoiding the need for each flight project to acquire and operate its own specialized space communications network. The DSN was given responsibility for its own research, development, and operation in support of all of its users. Under this concept, it has become a world leader in the development of low-noise receivers; large parabolic-dish antennas; tracking, telemetry, and command systems; digital signal processing; and deep space navigation. The Deep Space Network formally announced its intention to send missions into deep space on Christmas Eve 1963; it has remained in continuous operation in one capacity or another ever since.

The largest antennas of the DSN are often called on during spacecraft emergencies. Almost all spacecraft are designed so normal operation can be conducted on the smaller (and more economical) antennas of the DSN, but during an emergency the use of the largest antennas is crucial. This is because a troubled spacecraft may be forced to use less than its normal transmitter power, attitude control problems may preclude the use of high-gain antennas, and recovering every bit of telemetry is critical to assessing the health of the spacecraft and planning the recovery. The most famous example is the Apollo 13 mission, where limited battery power and inability to use the spacecraft's high-gain antennas reduced signal levels below the capability of the Manned Space Flight Network, and the use of the biggest DSN antennas (and the Australian Parkes Observatory radio telescope) was critical to saving the lives of the astronauts. While Apollo was also a US mission, DSN provides this emergency service to other space agencies as well, in a spirit of inter-agency and international cooperation. For example, the recovery of the Solar and Heliospheric Observatory (SOHO) mission of the European Space Agency (ESA) would not have been possible without the use of the largest DSN facilities.

DSN and the Apollo program

Although normally tasked with tracking unmanned spacecraft, the Deep Space Network (DSN) also contributed to the communication and tracking of Apollo missions to the Moon, although primary responsibility was held by the Manned Space Flight Network. The DSN designed the MSFN stations for lunar communication and provided a second antenna at each MSFN site (the MSFN sites were near the DSN sites for just this reason). Two antennas at each site were needed both for redundancy and because the beam widths of the large antennas needed were too small to encompass both the lunar orbiter and the lander at the same time. DSN also supplied some larger antennas as needed, in particular for television broadcasts from the Moon, and emergency communications such as Apollo 13.

Excerpt from a NASA report describing how the DSN and MSFN cooperated for Apollo:

Another critical step in the evolution of the Apollo Network came in 1965 with the advent of the DSN Wing concept. Originally, the participation of DSN 26-m antennas during an Apollo Mission was to be limited to a backup role. This was one reason why the MSFN 26-m sites were collocated with the DSN sites at Goldstone, Madrid, and Canberra. However, the presence of two, well-separated spacecraft during lunar operations stimulated the rethinking of the tracking and communication problem. One thought was to add a dual S-band RF system to each of the three 26-m MSFN antennas, leaving the nearby DSN 26-m antennas still in a backup role. Calculations showed, though, that a 26-m antenna pattern centered on the landed Lunar Module would suffer a 9-to-12 db loss at the lunar horizon, making tracking and data acquisition of the orbiting Command Service Module difficult, perhaps impossible. It made sense to use both the MSFN and DSN antennas simultaneously during the all-important lunar operations. JPL was naturally reluctant to compromise the objectives of its many unmanned spacecraft by turning three of its DSN stations over to the MSFN for long periods. How could the goals of both Apollo and deep space exploration be achieved without building a third 26-m antenna at each of the three sites or undercutting planetary science missions?

The solution came in early 1965 at a meeting at NASA Headquarters, when Eberhardt Rechtin suggested what is now known as the "wing concept". The wing approach involves constructing a new section or "wing" to the main building at each of the three involved DSN sites. The wing would include a MSFN control room and the necessary interface equipment to accomplish the following:

1. Permit tracking and two-way data transfer with either spacecraft during lunar operations.
2. Permit tracking and two-way data transfer with the combined spacecraft during the flight to the Moon.
3. Provide backup for the collocated MSFN site passive track (spacecraft to ground RF links) of the Apollo spacecraft during trans-lunar and trans-earth phases.

With this arrangement, the DSN station could be quickly switched from a deep-space mission to Apollo and back again. GSFC personnel would operate the MSFN equipment completely independently of DSN personnel. Deep space missions would not be compromised nearly as much as if the entire station's equipment and personnel were turned over to Apollo for several weeks.

The details of this cooperation and operation are available in a two-volume technical report from JPL.

Management

The network is a NASA facility and is managed and operated for NASA by JPL, which is part of the California Institute of Technology (Caltech). The Interplanetary Network Directorate (IND) manages the program within JPL and is charged with the development and operation of it. The IND is considered to be JPL's focal point for all matters relating to telecommunications, interplanetary navigation, information systems, information technology, computing, software engineering, and other relevant technologies. While the IND is best known for its duties relating to the Deep Space Network, the organization also maintains the JPL Advanced Multi-Mission Operations System (AMMOS) and JPL's Institutional Computing and Information Services (ICIS).

Harris Corporation is under a 5-year contract to JPL for the DSN's operations and maintenance. Harris has responsibility for managing the Goldstone complex, operating the DSOC, and for DSN operations, mission planning, operations engineering, and logistics.

Antennas

70 m antenna at Goldstone, California.

 

Each complex consists of at least four deep space terminals equipped with ultra-sensitive receiving systems and large parabolic-dish antennas. There are:

• One 34-meter (112 ft) diameter High Efficiency antenna (HEF).
• Two or more 34-meter (112 ft) Beam waveguide antennas (BWG) (three operational at the Goldstone Complex, two at the Robledo de Chavela complex (near Madrid), and two at the Canberra Complex).
• One 26-meter (85 ft) antenna.
• One 70-meter (230 ft) antenna.

Five of the 34-meter (112 ft) beam waveguide antennas were added to the system in the late 1990s. Three were located at Goldstone, and one each at Canberra and Madrid. A second 34-meter (112 ft) beam waveguide antenna (the network's sixth) was completed at the Madrid complex in 2004.

In order to meet the current and future needs of deep space communication services, a number of new Deep Space Station antennas need to be built at the existing Deep Space Network sites. At the Canberra Deep Space Communication Complex the first of these was completed October 2014 (DSS35), with a second becoming operational in October 2016 (DSS36). Construction has also begun on an additional antenna at the Madrid Deep Space Communications Complex. By 2025, the 70 meter antennas at all three locations will be decommissioned and replaced with 34 meter BWG antennas that will be arrayed. All systems will be upgraded to have X-band uplink capabilities and both X and Ka-band downlink capabilities.

Current signal processing capabilities

The Canberra Deep Space Communication Complex in 2008

 

The general capabilities of the DSN have not substantially changed since the beginning of the Voyager Interstellar Mission in the early 1990s. However, many advancements in digital signal processing, arraying and error correction have been adopted by the DSN. 

The ability to array several antennas was incorporated to improve the data returned from the Voyager 2 Neptune encounter, and extensively used for the Galileo spacecraft, when the high-gain antenna did not deploy correctly.

The DSN array currently available since the Galileo mission can link the 70-meter (230 ft) dish antenna at the Deep Space Network complex in Goldstone, California, with an identical antenna located in Australia, in addition to two 34-meter (112 ft) antennas at the Canberra complex. The California and Australia sites were used concurrently to pick up communications with Galileo. 

Arraying of antennas within the three DSN locations is also used. For example, a 70-meter (230 ft) dish antenna can be arrayed with a 34-meter dish. For especially vital missions, like Voyager 2, non-DSN facilities normally used for radio astronomy can be added to the array. In particular, the Canberra 70-meter (230 ft) dish can be arrayed with the Parkes Radio Telescope in Australia; and the Goldstone 70-meter dish can be arrayed with the Very Large Array of antennas in New Mexico. Also, two or more 34-meter (112 ft) dishes at one DSN location are commonly arrayed together. 

All the stations are remotely operated from a centralized Signal Processing Center at each complex. These Centers house the electronic subsystems that point and control the antennas, receive and process the telemetry data, transmit commands, and generate the spacecraft navigation data. Once the data is processed at the complexes, it is transmitted to JPL for further processing and for distribution to science teams over a modern communications network. 

Especially at Mars, there are often many spacecraft within the beam width of an antenna. For operational efficiency, a single antenna can receive signals from multiple spacecraft at the same time. This capability is called Multiple Spacecraft Per Aperture, or MSPA. Currently the DSN can receive up to 4 spacecraft signals at the same time, or MSPA-4. However, apertures cannot currently be shared for uplink. When two or more high power carriers are used simultaneously, very high order intermodulation products fall in the receiver bands, causing interference to the much (25 orders of magnitude) weaker received signals. Therefore only one spacecraft at a time can get an uplink, though up to 4 can be received.

Network limitations and challenges

70m antenna in Robledo de Chavela, Community of Madrid, Spain

There are a number of limitations to the current DSN, and a number of challenges going forward.

• The Deep Space Network is something of a misnomer, as there are no current plans, nor future plans, for exclusive communication satellites anywhere in space to handle multiparty, multi-mission use. All the transmitting and receiving equipment are Earth-based. Therefore, data transmission rates from/to any and all spacecrafts and space probes are severely constrained due to the distances from Earth.
• The need to support "legacy" missions that have remained operational beyond their original lifetimes but are still returning scientific data. Programs such as Voyager have been operating long past their original mission termination date. They also need some of the largest antennas.
• Replacing major components can cause problems as it can leave an antenna out of service for months at a time.
• The older 70M & HEF antennas are reaching the end of their lives. At some point these will need to be replaced. The leading candidate for 70M replacement had been an array of smaller dishes, but more recently the decision was taken to expand the provision of 34-meter (112 ft) BWG antennas at each complex to a total of 4.
• New spacecraft intended for missions beyond geocentric orbits are being equipped to use the beacon mode service, which allows such missions to operate without the DSN most of the time.

DSN and radio science

Illustration of Juno and Jupiter. Juno is in a polar orbit that takes it close to Jupiter as it passes from north to south, getting a view of both poles. During the GS experiment it must point its antenna at the Deep Space Network on Earth to pick up a special signal sent from DSN.

 

The DSN forms one portion of the radio sciences experiment included on most deep space missions, where radio links between spacecraft and Earth are used to investigate planetary science, space physics and fundamental physics. The experiments include radio occultations, gravity field determination and celestial mechanics, bistatic scattering, doppler wind experiments, solar corona characterization, and tests of fundamental physics.

For example, the Deep Space Network forms one component of the gravity science experiment on Juno. This includes special communication hardware on Juno and uses its communication system. The DSN radiates a Ka-band uplink, which is picked up by Juno's Ka-Band communication system and then processed by a special communication box called KaTS, and then this new signal is sent back the DSN. This allows the velocity of the spacecraft over time to be determined with a level of precision that allows a more accurate determination of the gravity field at planet Jupiter.

Another radio science experiment is REX on the New Horizons spacecraft to Pluto-Charon. REX received a signal from Earth as it was occulted by Pluto to take various measurements of that systems of bodies.