Walkerbots

Walkerbots
Anarchy enters the arena
Robots
Pioneer(s)	Bloodletter Jr., Rex & Roach (1996 US competition) Jim Struts (televised series)
Notable Robots	Anarchy

Walkerbots (also known as Walkers, Walking Robots or Legged Robots) are robots which use legs and/or feet as locomotion instead of traditional wheels or tracks. In televised Robot Wars series, they first appeared in The Second Wars, with Jim Struts competing in - and winning - the Reserve Rumble at the end of that series. The most successful walkerbot to have ever competed in televised versions was Anarchy, which reached the Heat Final stage and won the 'Best Engineered' award in Series 6.

Walkerbots were relatively uncommon, with fourteen traditional walkers having appeared across all televised versions. They also proved largely unsuccessful in combat, with only Anarchy and Clawed Hopper having progressed beyond the first round in the main UK Series.

In the original US competitions, walking robots first began competing at the 1996 event, in both the main championships (Roach, featherweight) and one-off exhibition battles (Bloodletter Jr. and Rex, heavyweights). Of these early walkers, Christian Carlberg's Buzzcut and Pretty Hate Machine would earn tournament match wins in 1997, with the latter reaching the Face-Off Quarter-Finals and the Melee Final in the lightweight category.

Definition

Jim Struts, the first walkerbot to appear in Robot Wars

Clawed Hopper slowly pushes Twister towards the pit

As their name implies, walkerbots use 'legs' and/or 'feet' as their sole method of locomotion, which enable them to 'walk' across the arena floor. The 'legs' and 'feet' can assume a variety of forms, including metal beams, bars, box-sections or pipes, and can be powered by a variety of walking mechanisms, such as gears (Anarchy), cranks (Stomp) or hydraulic actuators (Jim Struts, Eleven).

To encourage innovation and creativity, walkerbots were initially allowed to enter one weight class below their actual weight, or weigh more than conventional robots in the main heavyweight category. Both of these breaks also ensured allowances for the extra weight of the walking mechanisms they used. For example, heavyweight walkerbots were allowed to weigh up to 136kg/300lbs between Series 1 and 4, 350lbs/160kg in US Season 1-2 and 200kg between Series 5 and 7. However, some walkerbots competing in these series, such as Jim Struts and Series 4 entrant Millennium Bug, weighed substantially more than the maximum heavyweight walkerbot limit.

The original rules for walkerbots in televised series were derived from the rules first established in the 1995 US competition. Here, the upper weight limit for heavyweight walkers was initially set at 200lbs, a rule carried over into the 1996 iteration. For 1997, the upper heavyweight limit was increased to 300lbs, as later adopted by Series 1-4 of the UK show. A further increase to 350lbs was proposed for the 1998 and 1999 US competitions, though neither of these would take place.

Between Series 8 and Series 9, the maximum weight limit for walkerbots was reduced to 135kg - only 25kg higher than the limit for conventional heavyweights - somewhat discouraging them from those series of the rebooted Robot Wars. Stricter rules for walking mechanisms also applied, stating that legs were required to have 'at least 2 degrees of freedom' in order for robots to be eligible for the new walkerbot weight allowance. An example of an eligible mechanism given by the build rules and Robot Wars: The Official Handbook was one featuring legs operated by linear actuators. 'Jumping and hopping' robots were also allowed for the first time, but no such designs are known to have been attempted.

For Series 10, the weight limit for heavyweight walkerbots was increased to 145kg, in order to encourage more robots of their kind to be entered. However, no traditional walkerbots would appear in Series 10, and it is currently unknown whether any attempted to apply for that series.

Weight Classes

Weight Category	US 1995-1996	US 1997	Series 1-4	Series 5-7/ Extreme/ International	US Season 1-2	Series 8-9	Series 10
Featherweight	N/A	N/A	11.4kg	Unknown	N/A	N/A	17.6kg
Lightweight	N/A	N/A	22.7kg	Unknown	N/A	N/A	N/A
Middleweight	N/A	N/A	45.4kg	Unknown	N/A	N/A	N/A
Heavyweight	200lbs	300lbs	136kg/300lbs	200kg	160kg/350lbs	135kg	145kg

NOTE: Walkerbots participating in Series 1-4, US Season 1-2 and the 1995-1997 US events were allowed to enter one class below their actual weight.

Shufflebots

Shufflebots
Drillzilla, a highly successful US shufflebot
Robots
Pioneer(s)	Drillzilla

A variant of the walker, the shufflebot (alternatively shuffler), substitutes legs for long sections, or 'banks', of feet positioned in line with each other. The 'feet' move in an elliptical pattern, guided by a camshaft mechanism, enabling the robot to 'shuffle' across the arena.

Although no shufflebots ever competed in the UK Championship, robots from international series, such as the American Drillzilla, the German Ansgar and the Dutch Scarab utilised this 'shuffling' mechanism with varying degrees of success. Of these, Drillzilla was the most successful, winning the US Season 1 Annihilator and Tag Team Terror competitions, as well as finishing runner-up in The Second World Championship. Unlike traditional walkerbots, shufflebots tended to be much faster and have more room for tougher armour and more efficient weapons, as well as being much more successful in competition.

Shufflebots were originally classified as walkers and allowed double the weight limit in the heavyweight classes. However, in 2001, the distinction between them and walkers was officially recognised in the American robot combat show BattleBots, after a shufflebot, Son of Whyachi, won the Season 3.0 heavyweight division there. By Season 4.0, shufflebots using camshaft mechanisms were among the designs no longer eligible for the weight advantage formerly shared with traditional walkerbots. A similar rule would thus come into effect in later versions of Robot Wars starting with UK Series 6.

Despite the weight increase being abolished, the 200kg shufflebots Ansgar's Revenge and Ansgar 3 were still allowed to compete in German Robot Wars and The Third World Championship, which were filmed around the same time as Series 6 and Series 7 respectively.

Shufflebots were given further handicaps from Series 8 onwards, with the heavyweight limit for the new series being 120kg; a mere 10kg heavier than a wheeled or tracked heavyweight robot, and 15kg less than a conventional heavyweight walker. The heavyweight shufflebot limit was further amended to 125kg for Series 10 - although one robot, Apex, entered the latter series as a shufflebot, it was converted to its original two-wheel drive system shortly before filming began.

Weight Classes

Weight Category	Series 1-4	Series 5/ Extreme 1/ International	US Season 1-2	Series 6-7/ Extreme 2/ International	Series 8-9	Series 10
Featherweight	N/A	N/A	N/A	N/A	N/A	15.1kg
Heavyweight	136kg/300lbs	200kg	160kg/350lbs	100kg	120kg	125kg

NOTE: Shufflebots were classified as walkerbots prior to UK Series 6.

Advantages and Disadvantages

The primary advantage of walkerbots is their additional weight over conventional robots, while their primary disadvantage is their slower speed. Shufflebots like Drillzilla often achieved a compromise which enabled them to gain a weight advantage without sacrificing speed.

Advantages

Anarchy's weight prevented Judge Shred 2½ from completely flipping it over

Drillzilla rams Firestorm 3 into the pit release button

With the Series 5-7 weight allowance, Anarchy was able to employ a pneumatic flipper and axe of equal efficiency to those employed by wheeled or tracked designs

• Extra weight could make walkerbots much more difficult to flip than conventional robots. Notably, Anarchy was considerably heavier than the maximum lifting capacity of Judge Shred 2½'s flipper, and proved difficult to flip over when both robots fought each other in Series 6.
• Walkerbots could offer exceptional pushing power with their greater weight - even early walkerbots like Clawed Hopper were able to easily outpush opponents such as Hammer & Tong and Twister.
  • Shufflebots combined this extra pushing power with faster and lighter cam-driven mechanisms. Drillzilla was especially notable for its pushing power and high top speed, which ensured its success in The Second World Championship and numerous competitions in Extreme Warriors.

"...it's going to be mayhem on legs. Robot 101 is good, it's very reliable, but let's face it, despite its pneumatic stabber, it's not nearly nasty enough. Anarchy on the other hand is a walking weapon! Twice the weight limit means 4 times the weapons capability..."

— Mike Franklin, explaining the benefits of the walkerbot weight allowance on Anarchy's damage output

• Especially under the Series 5-7 build rules, the walkerbot weight allowance could still enable competitors of those designs to employ effective and damaging weapons. Team 101 captain Mike Franklin conceived Anarchy as a more potent successor to their previous machine 101, at one point quoting its high-pressure pneumatic axe as being equally powerful as the flipper of two-time UK champion Chaos 2.

Disadvantages

The gyroscopic motions of Clawed Hopper kept it on its feet even as its slow speed made it vulnerable to getting flipped in the first place

Anarachnid's (right) slow speed ensured that it took over forty seconds to approach Mammoth (left) during their Series 3 Walker Battle

Millennium Bug has one of its leg guards flicked off by Judge Shred 2

"Don't make any plans for next summers holidays, 'cause... Clawed Hopper will still be here. Err, very probably."

— Jonathan Pearce on Clawed Hopper's lack of speed

• Walkerbots generally tended to be considerably slower and less manoeuvrable than conventional wheeled or tracked designs, as a result of their more complex, cumbersome and generally inefficient walking mechanisms. Clawed Hopper was easily outmanoeuvred by Bigger Brother during their Series 4 eliminator, and was unable to turn front on in time to prevent it from being flipped by the latter.
• Earlier walkerbots had a tendency to become unstable while walking, as a result of their heavier weight and lack of balance. Ian Inglis of Team EyeEye discovered these issues while testing Jim Struts, and acknowledged them in an interview shown before the Series 2 Reserve Rumble.

"It's not very stable. It keeps on falling over in the garden, we've crashed a few rose bushes and things like that."

— Ian Inglis explains Jim Struts' stability issues to Philippa Forrester

• If exposed, the 'legs' of a walkerbot can be easily damaged or destroyed by most weapons. Millennium Bug in particular had its legs damaged by Judge Shred 2 and X-Terminator 2 during its Series 4 eliminator, while Black Widow's legs were smashed by Hypno-Disc.
• Most early walkerbots featured minimal or no weaponry, making them largely or fully incapable of damaging opponents. Some, such as Jim Struts and Stomp, were capable of using their walking mechanisms as weapons in spite of this, although their effectiveness was limited.
• While more difficult to achieve, walkerbots with a high ground clearance and/or centre of gravity are still susceptible to being toppled or flipped over. The featherweight Mammoth's defeat to DTK in the Series 7 Featherweight Championship was indicative of this.

List of Walkerbots/Shufflebots

Robots are listed alphabetically.

DESKTOP MODE ONLY: Walkerbots which are not heavyweight entries are listed with a green background. Shufflebots are listed with a blue background. Walkerbots from the 1996-1997 US competitions are listed with a purple background.

Robot	Sub-Type	Series Appearances	Notes	Image
Anarachnid	Traditional	Series 3	Walker Battles only; middleweight. Six pairs of legs driven by rotary mechanisms.
Anarchy	Traditional	Series 6	Eight legs made out of hardcoat-anodized 6082 T6 aircraft-grade aluminium, operated by gears, sprockets and chains. Rubber feet made from hose cuts. Armed with a pneumatic flipper and axe operating at 800psi. Series 6 Heat Finalist and winner of the 'Best Engineered' award in the same series.
Ansgar's Revenge	Shufflebot	Series 6, German Series
Ansgar 3	Shufflebot	Series 7	Competed exclusively in The Third World Championship. Armed with a horizontal spinning blade.
Apex	Shufflebot	Series 10	Arrived at Series 10 as a shufflebot and qualified on these grounds, but only one side of the shuffling system worked in testing. Following this issue, Apex was hastily reverted to its original two-wheel drive system before filming began.
Black Widow	Traditional	Series 5	Armed with a 180-degree axe and spikes.
Bloodletter Jr.	Traditional	1996 US Championship	Heavyweight. Very large six-legged machine claimed to weigh over the then-maximum 200lb limit, powered by two 'huge gearmotors'. Square aluminium tube frame; armed with '2 projecting spikes'. Fought a one-off exhibition battle against Rex.
Buzzcut	Traditional	1997 US Championship	Featherweight; one of the first two robots built by Christian Carlberg. Eight-legged walker incorporating steel rod frames, spring-loaded legs, aluminium 'cups' with racquet ball 'feet' and CNC-machined aluminium linkages. 'Split tapped' crankshafts, chains and clamps enabled a 'rowing motion', tank-like steering and independent drive on both sides. Powered by 14.4V Makita drill motors and batteries. Armed with two banks of four cutting saws - one on each end - powered by a 1.5hp weedeater motor. First walker considered to have won a battle in a main Robot Wars championship.
Clawed Hopper	Traditional	Series 4-5	Walking mechanism consisted of a rectangular frame moving in an elliptical pattern, and a turntable for turning round with a zero-degree circle. Frame equipped with spikes and steel claws. First walkerbot to win a battle in the main UK Series championship.
Drillzilla	Shufflebot	Extreme 1, US Season 1	Banks of four cam-driven 'feet' running on four 20hp electric motors. Top speed of 30-40mph; armed with cutting jaws and a rear drill. Second World Championship runner-up, US Season 1 Annihilator and Tag Team Terror co-champion.
Eleven	Traditional	Series 5	Four legs powered by hydraulics. Armed with a set of lifting/grabbing jaws.
Jim Struts	Traditional	Series 2	Reserve Rumble winner. First walkerbot to appear – and win a battle – in Robot Wars. Four legs operated by hydraulics and featuring 'ski-lift' feet. Feet were used to lift and clamp opponents.
Mammoth (46kg)	Traditional	Series 3	Walker Battles only. Though weighing 0.6kg over the standard middleweight limit, the eight-legged Mammoth was still likely considered as one due to the 'one class below' rule in place at the time.
Mammoth	Traditional	Extreme 1-2	Used two strips of metal as 'feet' and tubes as stabilisers. Entered into the Middleweight Championship in both series of Extreme despite being a lightweight.
Mammoth (Featherweight)	Traditional	Series 7	Featherweight Championship only.
Millennium Bug	Traditional	Series 4	Eight legs made from scaffolding pipes.
Miss Struts	Traditional	Series 3	Walker Battles only. Four legs powered by actuators.
NAMAZU	Traditional	Dutch Series 2	Eight legs. Armed with a vertical crushing arm.
Neoteric	Traditional	Extreme 2	Featherweight Championship only. Armed with a large vertical cutting disc.
Pretty Hate Machine	Traditional	1997 US Championship	Lightweight. Built by Christian Carlberg as a scaled-up version of Buzzcut, incorporating a similar eight-legged mechanism and design features. Driven by wheelchair motors rated at up to 24V. Armed with two banks of three cutting saws, each powered by its own 1.5hp weedeater motor. 1997 Lightweight Face-Off Quarter-Finalist and Lightweight Melee Finalist.
Rex	Traditional	1996 US Championship	Heavyweight. Large wooden and square metal tube construction; locomotion provided by rotary crank mechanisms with spiked 'blocks' gripping the floor. Fought and won a one-off exhibition battle against Bloodletter Jr. Shared its 'drive module' with Up & Over.
Roach	Traditional	1996 US Championship	Featherweight. Eight chain-driven legs powered by four 'kiddie car motors'. Steel frame; surrounded by various entanglement devices. Frequently suffered reliability and radio interference issues in combat.
RT 81	Traditional	Extreme 2	Chassis made out of a lorry tyre. Armed with an electric hammer mounted on a 360-degree rotating turret.
Scarab	Shufflebot	Dutch Series 2	Armed with large front pincers.
Snake	Traditional	1997 US Championship	Extraordinarily large and unusual heavyweight from Mark Setrakian, modelled on the limbless reptiles. Moved through armature controls and eight independently-controlled segments within its 'welded steel skeleton', each connected by linear actuators. Armed with '3-way' front jaws and a rear power drill. Recipient of the 'Strangest' award in 1997.
Stomp	Traditional	Series 3	Walker Battles only; middleweight. Pair of box-sectioned 'feet' designed to move together at the end of three cranks. Turntable used to turn the robot round and hit opponents with its 'feet' as it spun.

Trivia

• Although robots such as Anarchy were considered to be walkers in the original series, it would nowadays be classified as a shufflebot due to lacking a certain degree of freedom with its purely horizontal leg system.
• Each of the three international versions of Robot Wars featured one shufflebot in their domestic championships - Drillzilla in Robot Wars: Extreme Warriors, Scarab in Dutch Robot Wars, and Ansgar's Revenge in German Robot Wars. If Apex had competed as a shufflebot in Series 10, this would have represented every domestic championship with one shufflebot.