Robot Arena > Tutorials and Tips

IRL - A Beginner's Guide

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I've always been irked by the fact that there's no real one-stop shop that new members can come to to learn about exactly what IRL building is all about, as I think it would allay a lot of the confusion about exactly what is and isn't IRL legal that we sometimes see from new members. This guide will aim to solve that.

To start at the very beginning, there are three main building styles in Robot Arena 2. One is Unrealistic. This ruleset encourages players to create the most effective robot that they possibly can in Robot Arena 2, with no regard for appearance or realism. This build style is most often seen in Stock, unmodified Robot Arena 2.

Then there is what’s known as “Standard”. This ruleset introduces some elements of realism, but has the main aim still being effectiveness. Robots in this ruleset are not allowed to break the laws of physics like in Unrealistic, but are still allowed to do things that wouldn’t be possible in the real world in the name of effectiveness. This is most often seen in DSL or Ironforge.

Then, there is the style that this guide will cover. IRL. The main aim in this style is to create something that looks like what you might see on shows such as Battlebots or Robot Wars, and also to create something that just overall looks cool. Effectiveness isn’t totally eliminated from consideration in IRL. But it should come after realism and looks in this style of building. Generally this style is done in DSL-IRL 2.5, a link to which can be found here:;down=594

As a result of this, IRL has fairly strict rules about what is and is not allowed when building. There is one EXTREMELY important thing to note before I start going over the rules of IRL building though:


This subjectivity stems from the fact that IRL as a build style is as much about following the ‘spirit’ of the ruleset as it is about following the letter of the law. Hosts may reject a robot, even if it could technically be done in real life, if they feel it doesn’t follow the spirit of the rules by focusing on looks and realism before effectiveness. If effectiveness is your main goal, then Standard or Unrealistic building may be more your cup of tea.

Now that that's out of the way we'll start with the most basic tenets of IRL building. Some of these may seem like common sense to more experienced builders of IRL but it's totally understandable if a new member doesn't pick them up straight away.

Component Choice:
One of the first things new players to DSL (and by extension IRL) must learn, is that certain components are suitable for certain jobs. Nowhere is this more true than with motors. Compared to stock Robot Arena 2, DSL splits motors into two categories: weapon motors, and drive motors. Builders must use motors which are suitable for the job in hand if they are to make an efficient and effective robot. Using say, a weapon motor for drive, or vice versa will result in either a slow, sluggish robot, or an underpowered weapon, so this is something that builders must commit to memory to guide their motor choices when building. Below is a table containing all of the spin motors in DSL, and whether they fall under the drive, or weapon motor categories.


Below is an example of a motor being used incorrectly. Motors such as the piglet are often attractive as drive motors to new players due to their light weight which allows them to spend more weight on armour and weaponry, but in actuality this usage of piglet motors is extremely inefficient, and will result in a sluggish robot which struggles to defend itself against machines which use proper drive motors. Likewise is true for using drive motors to power a weapon such as a disc, though this is less commonly seen.


DSL 2.5 also adds a new type of weapon motor: overvolted motors. These motors provide much improved power to spinning weapons, often enabling robots to hit their opponents considerable distances if paired with a sufficiently heavy weapon setup. This extra power comes at a cost however. The overvolted motors weigh more than their standard counterparts, and you are also only able to use one per robot, as using multiple will cause the robot's control board to short-circuit and cause the bot to be unable to move. The voltages available for each motor depend on the size and stats of the base motor, with the largest motors such as the Perm 132, Etek or 4 Mag being available in voltages up to 72V, which represent the most powerful weapon motors available in the game.


Above are examples of overvolted motors available in DSL 2.5. They can be distinguished from standard motors from the voltages listed in the name (E.g. 24V, 48V, 72V)

Spinner Supports:

In IRL building, there is also the rule that all spinners, vertical or horizontal, must have adequate supports for the weapon axle. This is one of the most commonly overlooked rules of IRL building by newbies, but is also one of the few rules in IRL that can have little argument over it. Below are examples of a properly supported VS and HS by RedAce:


As you can see, both bots have rigid, triangular supports for their weapons made out of extenders. It's also important to note that the axle of the motor that he has used is supported by these extenders. This is possible thanks to component freedom, which is widely legal in IRL tournaments, and allows for the collision mesh of the extender and the motor axle to intersect, enabling the creation of proper supports.

Below are two examples of inadequate supports that would not be legal in IRL building. In the left example the motor has no supports at all as the axle is floating in mid air supported only by the motor chain (which obviously would not provide any support were this real life). In the right example the weapon has SOME support, but it is not at all adequate. The single extender would buckle as soon as the weapon hit anything in a real combat scenario, which means that this setup would not be legal.


It is also important to note that weapon motors must also be adequately protected and supported. RedAce's VS has some of its weapon motor exposed, but it is mounted well out of the way of any potential hits from opposing machines, and has a majority of it placed within the chassis, providing protection to it.

Wedge Design:
Wedge design is another point of contention in IRL building. An effective wedge can be absolutely crucial for bot designs like flippers and certain vertical spinners, so creating a wedge that is effective, but also realistic is of paramount importance. The kind of wedges which are often seen in Standard and Unrealistic building are very effective, but are generally not allowed in IRL building. Below is an example of a type of wedge which would be perfectly legal in Standard or Unrealistic, but is not allowed in IRL building


This wedge is very effective at getting under opponents, but it makes use of extremely thin, totally unsupported sheets of metal, which would buckle on first contact with an opposing machine in a real life combat scenario. We can apply some of the principles of wedge design used in Standard or unrealistic building to achieve similar wedge effectiveness while remaining IRL legal through various means. One popular method is to use wedgelets, as in the example below.


We can see in this example that the robot has 2 wedgelets extending out of the front of the robot in order to assist in getting under other machines. It is important to note that while obviously different from the example of an illegal wedge, it does use many of the same principles. For example, the wedgelets are each mounted on a metal hinge, and said hinge has been mounted in such a way that it is very low down in the robot, and the angle of the wedgelets are minimised. The reason that this setup for a wedge is legal where the previous example is not is because the wedgelets are sufficiently thick that they would not bend on contact with another machine like the wedge in the first example would.

An advantage of using wedgelets is that their small size can allow them to exploit tiny gaps in an opponent's ground clearance in order to get underneath them where other wider wedge setups may struggle to. The fact that they extend out the front of the robot can also allow a machine to "turn in" on an opponent and hook a wedgelet round to their side where they will likely have a higher ground clearance that is easier to exploit.

That said, there is one scenario where thin sheets such as those in the first example are legal in IRL building. This scenario is a "dustpan" wedge, which has been seen on real robots such as S.O.B from Battlebots. Below is an example of a dustpan in Robot Arena 2


Here, Hoppin has used the thin skirt panels, but has used armour panels on the side to provide support and stiffness to them. This means that this setup is legal, as it mirrors setups seen on real life bots such as S.O.B


Another popular method that has recently gained traction for wedges is the use of a panel and a wedge edge. This method trades some durability possessed by wedgelets for potentially better wedging ability if done right. Another advantage of a panel and wedge edge over wedgelets is that if covers the whole front of a robot with a highly effective wedge, whereas wedgelets can sometimes be negated by an opposing machine with longer wedgelets being able to bypass them completely to get under the main chassis without ever having to touch your machine's wedgelets An example of a robot that uses a panel and wedge edge effectively can be seen below:


Again, this method should use the same principles of wedge design mentioned earlier:

-   Mounting the hinge low down in the robot (but not so low down that it pokes out of the bottom of the machine and raises its ground clearance)

-   If using the skirt hinge, only using the centre attachment point (especially applicable if using wedgelets, where the two outer attachment points may look tempting to allow you to get 2 wedgelets while only having to use a single hinge component), as the outer attachment points have terrible wedging ability and will prevent you from getting under opponents effectively.

-   Minimising the angle of your wedge piece so that opponents don't have to climb up a steep slope when you get under them. You should still have sufficient angle on the wedge that the panel (or wedgelets or any other wedge you may be using) is pressed into the ground, however.

If done correctly all of this should result in a highly effective wedge, regardless of whether you use wedgelets, a panel and wedge edge, a dustpan, or even some other design. The best test of a robot's wedge is to enter it into some tournaments and see how it fares against other machines. You can then tweak it as needed to ensure that you're able to get under opponents as best as possible

Weapon Restrictions:
This is an extremely contentious point in IRL building, and is the source of much of the debate that surrounds the meta. There are some restrictions placed on both weapon types and quantities in IRL building, though these restrictions vary from tournament to tournament. In general though 'weapon spam' as it is known, is either disallowed, or looked down upon in IRL building, as it goes against the spirit of the ruleset that was mentioned at the start of this guide. Peoples' definitions of what constitutes 'weapon spam' vary. Some tournaments will place a hard limit on the number of teeth that a weapon such as a spinner can have. It is best to simply try to follow the rules of any tournament you enter, and make your own mind up about what you feel constitutes weapon spam over time.

Additionally, we do see some limitations on bot types that are allowed in IRL building. The "popup" bot type which aims to hit an opponent from below with a large number of weapons attached to burst motors or pistons, and is extremely popular in both Standard and Unrealistic building, is generally not allowed in IRL, as such a weapon setup would cause next to no damage in a real-world scenario.

Finally, there is the matter of flippers, and how many burst motors they're allowed to have. The number of burst motors allowed on flippers varies from tournament to tournament, like the limits on teeth, but these days the most common limits are 2 bursts for a flipper. Above 2 bursts on a flipper is extremely rare to be allowed.

Additionally there are often arc limits placed on flippers in modern tournaments. This is for two reasons. One is that almost every pneumatic flipper in real life has a flip angle of 90 degrees or less, so, considering the goal of this build style is to try to mirror real robot combat as best as possible, tournaments also place this restriction on RA2 robots. Additionally, in RA2, flipper power is quite heavily tied to the arc of the burst motor, and having over a 90 degree burst arc can allow flippers to be unrealistically powerful, which is prevented for balance reasons. The arc of the flipper is measured from the resting position, as can be seen in the image below.


You may think that as long as your bot looks realistic from the outside then you are good-to-go, but this is not the case. There are important restrictions placed on a robot's internals just as there are on the externals. Many new players assume that since component freedom is generally legal in IRL building, that it is also legal to intersect all components inside each other to create the most compact bot possible. This is untrue. IRL follows similar rules to Standard building in this regard. A component may only intersect with another where a slot could feasibly be cut in real life. This means that components such as motors, batteries, air tanks and control boards may not intersect with one another. However, static, non-electrical/mechanical components such as extenders may intersect with other components, including control boards, motors etc, so long as a slot/hole could be cut to accommodate them in real life. Additionally, moving parts may under no circumstances intersect with other moving parts.

Below is an example of a weapon setup which would not be legal. From the outside of the bot, all looks fine, but when we look inside, we can see that the weapon bar will cut straight through the weapon motor as soon as it spins, which renders this setup illegal in IRL building.


Here is another example of unacceptable clipping in IRL building. Here, we can see that the drive motors intersect with the weapon motor. While this may help get a more compact bot, it is not acceptable in IRL building, as there is no way a slot could be cut through the weapon motor in order to accommodate the drive motors.


Below is an example of clipping that would be deemed acceptable in IRL building. The extender is colliding slightly with the weapon motor, but because an extender is simply a solid hunk of metal, unlike a motor, a slot could be cut out of the extender to accommodate the clipping with the motor were this a real robot, which means that clipping of this nature is deemed acceptable in IRL building.


Extenderbots and OBJ2RA2:
These are two terms that may be confusing to new members, but that are growing ever more prevalent in IRL building. An extenderbot is a robot which has little to no chassis (often they will make use of a "pixel chassis" which is contained within an extender anchor, which provides a base to build off of. This chassis is available here:;pic=5769), and is made up almost entirely out of extenders and armour plates, making use of the component freedom mod to break the "rule of 7" (in default Robot Arena 2 you can only have a maximum of 7 components in a chain) and to place extenders and panels in places that you would otherwise not be able to. This has several advantages and disadvantages. An advantage of extenderbots is that you can achieve shapes that would be impossible to achieve with the default chassis creator in Robot Arena 2. Below is an example of an extenderbot with such a shape:


Furthermore, the fact that extenderbots are made out of breakable components allows for more realistic destruction than traditional robots (or chassisbots as they are also known), with chunks of robots being able to be ripped off, and internals such as motors becoming exposed. Such destruction comes with a major drawback though. Damaging extenderbots places a lot of strain on the outdated physics engine of Robot Arena 2, which can lead to crashing or 'havok explosions', especially when they are used in rumbles (The third and fourth slots in a fight are far more unstable, so fights that make use of them such as rumbles and tag team matches are far more likely to havok or crash than regular 1 vs 1 fights)

Another option to minimise crashing and havoking is OBJ2RA2. This is a technology pioneered by Apanx, and enables you to import any .obj file as a chassis into Robot Arena 2. This allows for similar complex chassis shapes to extenderbots (though it lacks the more realistic destruction) while placing less strain on the physics engine. Because it is such a new development it has lacked the widespread adoption that extenderbots have seen, and it is also somewhat complicated and difficult to grasp for many members, but those who do make use of it have produced some fantastic results


Component Legality and Cheatbot2:
Many IRL tournaments allow the use of 'cheatbot2' components. cheatbot2 (commonly known simply as CB2) is a feature in Robot Arena 2 where you can name your robot 'cheatbot2' in order to access a plethora of hidden, sometimes extremely powerful components. Many IRL tournaments only allow certain cheatbot2 components, as many of them are extremely unbalanced and not suitable for tournament use. Make sure to read each tournament's rules on cheatbot2 components carefully before using them in order to ensure your robots are not rejected.

Bot File Editing:
The last point I will touch upon in this guide is bot file editing. Despite the daunting name this process is relatively easy, with guides how to perform various tasks using bot file editing (commonly referred to as BFE) here: , here:'s-guide/ and here:'s-burst-motor-have-an-180-degree-arc/msg646794/#msg646794 .

BFE allows builders to do a plethora of things that are not normally possible in the game, such as create a chassis lower than the normal minimum height achievable, move components around after they have been placed, or change the colour or material of a component after it has been placed. BFE is often legal in IRL tournaments, though some limit what it can be used for. Again, be sure to read the rules of the tournament before building your robot to avoid getting rejected.

I hope this guide proves useful in at least dispelling some of the myths around IRL, and cluing new members in on exactly what it's about so that there's less confusion when new people join. Many thanks to RedAce, Hoppin and Tashic for allowing me to use some of their bots as examples in this guide.


--- Quote from: TheRoboteer on November 09, 2018, 09:58:14 AM ---Many new players assume that since component freedom is generally legal in IRL building, that it is also legal to intersect all components inside each other to create the most compact bot possible.

--- End quote ---

Kix also believes this. :dumb)


--- Quote from: Hoppin on November 09, 2018, 10:19:32 AM ---
--- Quote from: TheRoboteer on November 09, 2018, 09:58:14 AM ---Many new players assume that since component freedom is generally legal in IRL building, that it is also legal to intersect all components inside each other to create the most compact bot possible.

--- End quote ---

Kix also believes this. :dumb)

--- End quote ---
Remember new players, never be a Kix

It's an actually great guide. Nice job TR

croat bashing aside, this is a great guide. definitely one of the best ones I've seen for building


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