Sit-and-spin

Sit-and-spin
Nuts 2's flails sever Carbide's weapon chain
Weapon Category	Thwackbot
Robots
Pioneer(s)	Tiny Tim (1994 US competition) Spin Doctor (televised series)
Notable Robots	Test Toaster One, Bob Smith (1994-1997 US competitions) Stinger, Dantomkia, Nuts 2, Lizzard (televised series)

Sit-and-spin robots are one of two forms of thwackbot to appear in Robot Wars. They work under the same principle as a full-body spinner, in that the entire robot is designed to act as a heavy spinning object which makes contact over a small surface area.

The first instances of robots performing sit-and-spin tactics occurred in the original 1994 US competition. Heavyweights Tiny Tim and The Beetle were among the competitors documented to employ these in Face-Off and Melee events, the former through optional side spikes intended for this purpose. The House Robot from this event was also seen performing similar attacks on competitors, albeit with a damaged weapon.

1995 saw three competitors designed primarily with sit-and-spin attacks in mind - the middleweight Scorpion, and the lightweights Sonic and Test Toaster One. Test Toaster One was also the first to achieve notable success, winning the 1995 Lightweight Face-Off championship outright. Another successful sit-and-spin robot from this era was 1997 featherweight Bob Smith, which reached the Face-Off quarter-finals and Melee Final in its weight class.

Series 2 competitor Spin Doctor was the first UK machine to employ a sit-and-spin design, with robots of this kind occasionally achieving major success in televised series. Among the most notable and successful of these include Series 10 joint-third place finisher Nuts 2, Series 6-7 Semi-Finalist Dantomkia (although it mainly relied on its rear-hinged flipper to succeed) and Dutch Series 1 runner-up Lizzard. Some axlebots with torque reaction weaponry also possessed sit-and-spin capabilities, a notable example being Series 4 third-place finisher Stinger.

Definition

• Sit-and-spin refers to any robot whose only method of attack is to spin on its own axis in hope of damaging opponents when they drive close to it. In order to inflict damage, most robots of this kind were armed with a sharp or blunt weapon (e.g. spikes), usually along the ends or edges of their main body. Some designs featured a circular body with spikes, blades or sharp edges along the sides. Others incorporated static weaponry (e.g. small hammers or pickaxes) as part of a 'tail' attachment, with the intention of swinging the damaging point directly into opponents.

Meltybrain

"A "Meltybrain" controller works by measuring how fast the robot is spinning, and then stopping each motor for a section of the rotation. Repeating this over and over causes the robot to move forward whilst spinning. By having the drive system power the weapon as well, it reduced the cost and made the robot more reliable by having fewer moving parts."

— Rory Mangles explains the Meltybrain concept in Robot Wars: Build Your Own Robot

CycloneBot, a US pioneer of modern Meltybrain-equipped robots

Sit-and-spin designs waned in popularity as more advanced and effective spinning weapons became more commonplace. However, an innovative approach to the concept was discovered and developed by various US roboteers, taking the form of a control system allowing sit-and-spin robots to move and spin at the same time. The system, dubbed Meltybrain, involves equipping a sit-and-spin robot with LEDs and a motion detection system, enabling the robot to calculate its rotational speed and move across the arena in a controlled manner while spinning. The latter is achieved by programming one drive motor to stop at certain parts of any given rotation, the resulting action being described in the wider robot combat community as translational drift.

Though known to have been first attempted by original BattleBots middleweight Blade Runner, the Meltybrain concept would not be utilised by a Robot Wars competitor until Nuts 2 in Series 10, with outstanding success.

Advantages and Disadvantages

Advantages

Lizzard uses its tail and sit-and-spin tactics to attack Project Two: Hex'em

Spin Doctor's design enabled it to break off one of Matilda's tusks and prevent her from pushing it

• Since the sit-and-spin design works under the same principles as those of full-body spinners, robots built this way could theoretically be as damaging as the latter weapon type. A notably effective sit-and-spin robot is inaugural Dutch Robot Wars runner-up, Lizzard, which used its tail to severely damage Neater's lifting forks during their Heat Final in the second series.
  • The damage potential of a sit-and-spin design can be greatly increased with Meltybrain technology. With this installed, Nuts 2 was able to damage Concussion's wheels and side panels, rupture Androne 4000's hydraulic lines and break Carbide's weapon chain with its flails during its Series 10 run.
• The sit-and-spin design provides a great degree of protection from various attacks - including ramming - since such attacks will often result in opponents being deflected away upon contact. This was best shown in Spin Doctor's performance in the Series 2 King of the Castle Trial, where its shape and sit-and-spin tactics consistently prevented Matilda from being able to push it off the platform.
• Due to a sit-and-spin robot requiring no powered weaponry, robots of this nature were very easy to produce, and some robots such as Dantomkia could resort to sit-and-spin tactics if they could not rely on their primary, powered weapons.

Disadvantages

Carbide removes Nuts' rotating ring

• While it can be effective at damaging other robots in its range, a conventional sit-and-spin robot cannot usually move and attack at the same time; to attack, it must spin on the spot.
  • Spinning in place is not considered to be an aggressive tactic, a factor which can count against a conventional sit-and-spin robot in the event of a Judges' decision.
    • Both of these problems can be rectified with a Meltybrain. However, heavyweights generally do not use this technology, and Nuts 2's Meltybrain was very slow due to poor traction on the floor.
• If a sit-and-spin robot loses drive to one or more wheels on either side through any method, both its locomotion and main weapon will become incapacitated, as the robot relies purely on its drive system to attack. Nuts 2, for example, was unable to attack at all after one of its drive motors failed seconds into its Series 9 Group Battle.
• Series 7 and the three reboot series implemented a rule which required all robots to possess an active weapon, which sit-and-spin robots would technically violate. Nevertheless, robots such as T-Wrecks and Nuts 2 still qualified for the televised series regardless.
• Certain sit-and-spin robots were necessarily fragile, and their weapons could easily be damaged. This happened most infamously during Nuts' Head-to-Head battles with Carbide and Terrorhurtz in Series 8; in each battle, Nuts' opponents were able to remove the rotating ring, leaving it without any means to damage them in response.
  • Nuts 2's ring was broken by Carbide again in the Series 10 Grand Final. However, Team Nuts later stated that the ring was not welded properly, and would not have broken so easily otherwise.

List of Sit-and-Spin Robots

Robots are listed in alphabetical order.

DESKTOP MODE ONLY: Robots which are not heavyweight entries are listed with a green background. Robots from the original 1994-1997 US competitions are listed with a purple background.

Robot	Series Appearances as Sit-and-Spins	Notes	Image
Abaddon	Series 3	Whipping tail with hardened steel chisels. Originally supported by a repurposed bowling ball, the tail was modified to roll on a castor before combat.
Ajjay	Extreme 1	Was intended to be a full-body spinner, but instead resorted to sit-and spin tactics.
Armour-Geddon	Series 3	Primarily a torque reaction thwackbot; the end of the main swinging arm featured pairs of side-facing spikes.
Bluemax	Dutch Series 2	Whilst its primary weapon was a pincer, Bluemax was also equipped with a rear ball-and-chain which it utilised in a sit-and-spin manner during its only battle.
Bob Smith	1997 US Championship	Featherweight. A 'jointed spring-loaded tail' tipped with a small hammer head, capable of denting opponents' armour. 1997 Featherweight Melee Finalist and Featherweight Face-Off Quarter-Finalist.
Brawler	US Season 2	Armed with two static weapons - a diamond-edged spear on one end and a sledgehammer on the other. The robot itself was capable of spinning on the spot at 200rpm, with the intention of hitting opponents as they came into contact with either of its weapons.
Coyote	Series 10	Coyote's 10kg minibot Roadrunner uses a birdlike sit-and-spin design.	Roadrunner
Crasha Gnasha	Series 3	Featured a swinging tail concealing a hinged 4lb sledgehammer.
Dantomkia	Series 6-8, Extreme 2	The robot was capable of spinning on the spot at 450rpm (500rpm in Series 8); its front wedges could be used as spikes to damage opponents as its spun round. Limited usage; Dantomkia instead mainly relied on its rear-hinged flipper.
Dee	Series 9	Stock Robot. Effective at both torque reaction and sit-and-spin tactics. Later rebranded as Rabid M8.
Destructomatic	1997 US Championship	Featherweight. Two red chains attached to either side. Devised as a backup weapon when the robot's originally-planned claw proved too cumbersome in testing.
Fuzzy	1997 US Championship	Featherweight. Pair of swinging chain flails with metal weights and grey plastic tubing; the tubing was later replaced with duct tape. Quoted by Will Wright as capable of spinning at around 300rpm.
IDO	Dutch Series 2	Equipped with a static, horizontally-mounted pickaxe at the rear, used to damage opponents when spinning in place.
Impact	Dutch Series 2	The hammer was covered in fur that was often set alight.
Lizzard	Dutch Series 1-2	A swinging, articulated 'swan tail', with 'agricultural steel' cutting blades in Dutch Series 1 and a tip-mounted mace in Dutch Series 2. Dutch Series 1 runner-up, also reaching the Grand Final in Dutch Series 2.
Marvin	1996 US Championship	Centrally-hinged 'lifting beam' was fitted with a front spike and rear chains; the chains were used for sit-and-spin and entanglement strategies.
Micro Mute	Extreme 2, Series 7	Featherweight Championship. Relied more on its speed and wedge shape to win battles.
Mini-Maul	Series 7	50cm rear spike originating from a garden fence, facilitating sit-and-spin tactics.
Nuts	Series 8-10	Outside ring originally turned vertically independently, giving the robot a moving weapon. The ring is fitted with chain flails which are designed to swing outwards and hit opponents. Returned to Series 9 as Nuts 2, with planned Meltybrain technology and interchangeable rings, with the Meltybrain technology utilised in Series 10. Third place finisher in Series 10.
Rabid M8	Series 10	A loanerbot which previously competed as Dee. Effective at both sit-and-spin and torque reaction tactics.
Rhino	1997 US Championship	Sharp 'points' at the front and rear were used for ramming and sit-and-spin attacks. Also equipped with a Halon gas system for disabling internal combustion engines.
Scorpion	1995-1996 US Championships	Middleweight; 1995 incarnation alternatively referred to as StingRayBot. A double-ended pickaxe was incorporated into the 'hook-like tail', enabling sit-and-spin capabilities.	Scorpion (StingRayBot) strikes the cutting disc of Have a Nice Day
Sonic	1995 US Championship	Lightweight. Armed with a horizontal static hammer at the front.
Spin Doctor	Series 2	First sit-and-spin design in televised series. Managed to rip off one of Matilda's tusks.
Stinger	Series 3-6, Extreme 1-2, US Season 1	Primarily a torque reaction thwackbot; the mace used from Series 4 onwards would also be capable of inflicting sit-and-spin attacks. Third place in Series 4.
Stomp	Series 3	Walking robot, used its large box legs as weapons when spinning.
T-Wrecks	Series 7	The only heavyweight robot in Series 7 not to feature an active weapon.
Test Toaster One	1995-1996 US Championships	1995 Lightweight Face-Off Champion. Equipped with a large nail (later replaced by a double-sided metal blade) for impaling or pushing opponents forward.
The Grinch	1997 US Championship	Featherweight. A decidedly 'last minute' build equipped with two horizontally-mounted sledgehammers.
The Swarm	Series 10	One part of the four-part clusterbot, Skye, features a six-spoke 'windmill' structure with tyre sections. The structure is used to hit opponents when the robot spins, and has entanglement features.	Skye
The Tartan Terror	Series 5	Armed with a horizontally-mounted ice pick mounted to the robot's base.
Tiny Tim	1994 US Championship	Small spiked blades attached to the rear corners, used in the multi-class Melee. First competitor with design features intended for sit-and-spin attacks, though primarily armed with a front forklift.
Wizard	Series 2	Equipped with a set of chain flails with drill bit tips.