Self-righting mechanism

The self-righting mechanism (or srimech, derived from the words self-righting mechanism) is something of an essential in Robot Wars. In its simplest terms, it is a device used to flip a robot back onto its wheels if it gets flipped over. Although the first attempt to self-right in the UK Series was by Chaos, after being flipped over by Matilda in Series 2, the first successful srimech in the UK Series was used by Cassius also in Series 2, where it used its flipper to right itself after being overturned by Sir Killalot.

Powering
Usually, self-righting mechanisms are powered by either pneumatics (usually as part of a flipping weapon, Chaos 2 and Cassius were some of the first robots to have utilised these systems) or by an electric motor powered by the battery, Hypno-Disc and Panic Attack used these rather rare systems to great effect. However, there are also occasionally self-righting mechanisms powered by other means. Razer's self-righting wings are a good example-they were moved up and down by a steel cable attached to the weapon, allowing it to self-right, as well as give its infamous "salute".

Origins of the Srimech
The origins of the self-righting mechanism lie not only in UK Robot Wars, but in the original US competition, and famous robots Biohazard and Vlad the Impaler.
 * In 1996, Biohazard defeated rival machine Vlad the Impaler by pinning it against the wall for 30 seconds. The match ended and Biohazard released its foe, but Vlad, apparently disappointed at the loss, turned and used its pneumatic lifter on Biohazard to flip and immobilize it. Biohazard was able to self-right by use of its electric lifting arm. This is generally believed to be the first display of self-righting at a tournament, but it took place after the conclusion of a match and had no bearing on the outcome.
 * In 1997, in another match between Biohazard and Vlad the Impaler, Vlad demonstrated its special pneumatic device that could quickly and repeatedly pop Vlad back upright from an inverted orientation. The device was successfully used to self-right from an immobilized position several times, but Vlad lost the match in a judge's decision.
 * In Robot Wars: The Second Wars, Cassius was flipped onto its back by Sir Killalot during the Pinball trial. Despite this, Cassius used its flipping arm to self-right, landing on its wheels and managing to continue the Pinball trial. This was the first recorded time that a srimech had allowed a robot to continue in a tournament.
 * Later in that Series, Cassius was fighting reigning UK Champion Roadblock. Cassius was once again flipped over, but used its righting arm to land back on its wheels and go on to defeat Roadblock in battle. This was the first ever recorded instance of a robot going on to win a battle after being flipped.

The term was coined by Rex Garrod after Cassius self-righted for the first time. All three robots are credited with the evolution of the Self-Righting Mechanism, and are all members of The Combat Robot Hall of Fame.

Types
During the show's history, there were three different sorts of srimech.

Weapons
One of the ways a robot could self-right was through use of its own weapon. This was in fact the original UK Robot Wars srimech, as Cassius used its flipping arm to right itself, and Chaos could also right using its flipping arm (although it failed on TV). After Series 2, more robots began to use their flippers to self-right, and most robots with flippers, like Firestorm, Bigger Brother and Thermidor 2 were all capable of doing so. In Series 4, Iron-Awe became the first robot to self-right using an axe, and this was followed by others such as Dominator 2 and Terrorhurtz.

The advantage of self-righting through use of a weapon, such as flippers or axes, is that focus can be put on the weapon itself without having to make room for a secondary feature to right the robot. The main disadvantage, however, is that it depleted the effectiveness of the weapon after a while, and if the weapon power ran out, the robot would no longer be able to self right. This ultimately cost robots like Chaos 2 and Tsunami.

Separate Mechanisms
Not every weapon was able to right the robot, so often an alternative mechanism was used for robots that did not possess flippers or axes. A huge range of features were used across the show's history.

These srimechs had advantage in that they did not detract from the robot's weapon, but at the same time they could often be easily targeted and were prone to failure if enough damage had been caused. This was of particular relevance to Panic Attack, whose self-righting lid broke after Refbot tried to free it from the arena wall in the Commonwealth Carnage in Extreme Series 2. 13 Black's side-bar srimech was also susceptible to failing, as it did in both of its battles in Series 7.

Body Shape
A third, rarer form of self-righting came from the robot's body. Some robots, such as Velocirippa and The Morgue were designed so that no matter how much it was flipped, it would always be able to roll back onto its wheels, in a similar manner to the rollcage feature. The first robot that had this feature was Ivanhoe in Series 2, but it failed to work.

Although extremely effective if designed right, it was difficult to get that right design. It was also possible to become stranded if the robot was flipped over in just the right position (as Robochicken proved in Series 7, flipping Mega Morg straight into its back after a frontal attack), or there was not enough momentum behind the flip (which cost Ivanhoe as it was lifted onto its side by G.B.H.).