Antweight arena designs

[Tufty]

Hi all,

There's the potential that I might be getting a windfall in the semi-near future (yay, paralysis ) and I figure why not invest in something we can all enjoy/destroy together. Knowing arenas are pricey and deceptively difficult to build, I was wondering about people's feelings on a few potential design features. Having read through the most recent arena questions thread I can find - https://robotwars101.org/forum/viewtopi ... =10&t=2640 - I figure a 1m^2 arena floor will probably be sufficient, with a roughly 20cm trench on two sides.

So far, all normal. But aside from the obligatory gaps in the arena wall for pitting purposes, are there any rules against arena hazards? I was thinking of something like low-ish speed spinners in the corners, in theory not up to battle-ending strength but an extra tactical headache all the same. My original thought was to have one dead centre of the arena, but I can see that causing a lot of issues and just generally getting in the way. I similarly considered a floor spinner as the BBC tried for the 6th wars, but ants are hard enough to control without a portion of the floor suddenly getting drunk.

The floor itself would ideally be metal, most likely 3mm aluminium, which I realise could cause traction issues but it'll be the same for everyone. Plus both the BBB and custom-made tyres/tracks tend to be pretty grippy regardless of the surface. I thought about plastic or wood but both are easily damaged, and having just watched AWS62, I feel like wood and plastic are definitely not going to survive unscathed if a spinner hits them! I'd rather avoid running repairs mid-tournament.

As with the aforementioned 2018 discussion, I'm thinking of ways to get the cameras as close as possible to the action without them also becoming cannon fodder. They'll still need some sort of protection, but I think I can work around that easily enough. It would mean videos taking longer to be edited (multiple angles = more cutting, after all) but could potentially be worth it. I'd likely buy a set of the BBB playable kits and set up a mock tournament to see how viable that level of work would be.

In terms of accessibility, the two sides with pits would be hinged and triple bolted (better safe than sorry, even if I'm sure the third bolt would be overkill) which in theory should prevent any machine ending up out of reach.

Where do people stand on minimum roof height? I'd aim to go higher, naturally, but that sort of thing is useful as a starting point. The verts and flippers really need to get air!

The big safety question of course is what thickness of polycarb I need to get for the walls and roof. I've read various numbers on this topic, but I'm also acutely aware that spinners will continue to get more powerful and greater tolerance than, say, 5 years ago needs building into this.

That's everything I can think of for the moment, but if there's anything else people want to add that I've missed or perhaps haven't considered, by all means throw it at me.

[MySolderIsOlder]

One thought on floor material is that while aluminium may sound more durable than softwood, a hardox or titanium disk will still take big divots out of it and leave nasty gouge marks that would quickly make life difficult for low wedges/acetate. Then you've got the challenge of filing/burnishing out the damage.

With a wood floor, it's a 30 second job to scrape away splinters and high-spots between fights - then you can apply wood filler, sand and repaint after the event. With an aluminium floor, running repairs are going the be a lot harder. For my spinner test box I initially used a polycarbonate floor but that also proved difficult to repair, so in the end I went back to plywood.

If I were building a competition arena, I'd make a replaceable floor out of relatively thin birch ply (e.g. 4-6mm) that can sit on top of the main floor. Hold it down with edge clips or small patches of dbl-sided tape. Provided you have one to use as a template, you can then cut a few spare 'false floors' and even swap them out mid-tourny if the damage is bad.


As for arena hazards, personally I'm not a fan. All the antweight events I've attended have been more than exciting enough without them - and they just increase the likelihood of a weaker bot/drive winning by chance. Drop-offs are more than enough of a hazard for me! Still, if you did go the plywood false-floor route described above, that leaves you with the option of making 'slot-in' arena hazards for special events, without them getting in the way for regular AWS contests.

[minionhunter]

There is a guy on here from Australia who uses a stainless steel floor for his arena and likes it a lot. He said he first went with harder steel but then everyone started using magnets for down force and it because a big problem and that was the only way to win. Stainless doesn't have that problem.

I thought about metal and it seems desirable, but I think it will suffer and in the long run using a replaceable plywood floor (for ants) is the way to go. I also thought about hazards, but I really like the pits only as the hazards (in the rules for AWS). I don't really like the flipper BBB uses, but it is OK I guess. I'm a BIG fan of Peter Waller's arena, it is almost perfect IMHO (not too big, not too small). I'm still working on mine.

You might want to check out some of the Australian arenas which are designed much more around trapdoor pits and knockouts, but there is a cool black floored one and the guy's with the stainless steel.

I also like the arena that, I'm blanking on his name, has that is much bigger that has sliding doors. It is very posh. I think a combo of Peter's stage with the bigger box with sliding doors is my dream arena that I'm working towards here in the US.

Good luck!

[Tufty]

Thanks both.

In terms of hazards, it's a fair point about being able to switch them in and out depending on the competition. That's something I forgot about with the AWS rules. Obviously for different tournaments I've got more freedom in that regard, but if the prevailing opinion is they're unpopular then I'll put that aspect on the back burner for now.

I notice neither of you mentioned size so I'm assuming what I'm thinking is already acceptable, although obviously at the planning stage that's probably one of the easiest things to change, it just scales everything accordingly. As for material, if plywood is the generally accepted smart choice for the above reasons, I'll adhere to the wisdom of it. I hadn't considered how much damage an antweight spinner might do to metal!

I believe it was Peter's arena used at AWS61 (and I agree, it's a beautiful arena, even if a slight steering issue meant I went straight into one of those corner pits!) and the only thing about it that I didn't like was the need to lift the entire polycarb box to get robots in and out. Hinged doors to me seem the simplest and most convenient, but I don't think there's a definite right or wrong there.

The main outstanding question then is the ideal thickness of polycarb from the safety angle.

[minionhunter]

Thanks both.

In terms of hazards, it's a fair point about being able to switch them in and out depending on the competition. That's something I forgot about with the AWS rules. Obviously for different tournaments I've got more freedom in that regard, but if the prevailing opinion is they're unpopular then I'll put that aspect on the back burner for now.

I notice neither of you mentioned size so I'm assuming what I'm thinking is already acceptable, although obviously at the planning stage that's probably one of the easiest things to change, it just scales everything accordingly. As for material, if plywood is the generally accepted smart choice for the above reasons, I'll adhere to the wisdom of it. I hadn't considered how much damage an antweight spinner might do to metal!

I believe it was Peter's arena used at AWS61 (and I agree, it's a beautiful arena, even if a slight steering issue meant I went straight into one of those corner pits!) and the only thing about it that I didn't like was the need to lift the entire polycarb box to get robots in and out. Hinged doors to me seem the simplest and most convenient, but I don't think there's a definite right or wrong there.

The main outstanding question then is the ideal thickness of polycarb from the safety angle.

I think Peter's thread on his lists it.

I think BBB built theirs as a modified version of Peter's with the hinged side panels. They have a YT of them building it in timelapse fashion.

I think that they used two, 2mm thick sheets of polycarb for the wrapped ceiling/top to get 4mm.

Kyro commented in my thread that you need 4mm if you are going to have spinners.

Here is the response for the arena with the stainless steel floor from my thread. He seems to have had good success and doesn't have to replace the floor each event. You might not want to discount the stainless option, just think about what he's learned.

Re Antweight arena design ..
I designed and built the Ant arena that we use here.
It has a fighting floor area of 1100mm x 1400mm with pits at each end.
Originally there were low pit walls, with 250mm wide openings/drop offs, but later 150mm high pit walls and sliding pit "gates" were added.
The floor is 0.5mm thick galvanised sheet steel laminated onto MDF. It has held up really well, with no maintenance required.
The battle box is "frameless" 3mm polycarbonate, hinged on one side for access. It provides really good optics. (Credit this concept to Peter Waller)
Easily detached legs mean it is not reliant on available tables.
When I built it in 2017 there was no scene here, so I was guessing how things might pan out.
I tried to incorporate the best aspects of what I saw in the UK arenas.
If I was to design it again, knowing what I know now, I would consider ..
- Making the floor area a bit smaller (My original thoughts anticipated the possibility that 1 lbers may have been a thing here)
- Make the floor from 0.5mm austenitic stainless steel, as magnets have become fairly dominant here and are a bit contentious.
- Make the battle box collapsible for transport, as the bulky nature of the present one limits the transport options.
You can see several shots of the arena in action in the videos here .. https://www.youtube.com/channel/UCI1ZSy ... VYA/videos
Mike.

Re magnets on the Antweights becoming contentious here ..

I initially made the floor with galvanised sheet steel as it seemed to be cost effective and likely durable.
But after a while it occurred to me to build a bot with magnets to see if there was much benefit.
Of course, not being able to help myself , I developed a method for casting silicone tyres with magnets around the circumference.
This turned out to be very effective, and provided enough traction to stall N20s.

Then several builders started mounting magnets under their bots.
Some of them so strong that the bots could barely drive.
As a few builders figured out the right balance of magnets, often to compensate for otherwise uncontrollable spinners, they became fairly dominant, so much so that it looked too intimating for newbies to even build and compete.
Our scene has not been established for very long, and I am keen to encourage as many new participants as possible.

Then there was talk about rules to restrict the use of magnets.
For me, making and obeying rules should be a minimalist activity.
I far prefer creating an environment to encourage the results you want, rather than offering temptation but telling people its not allowed.

So I fitted the stainless floor.
Surprisingly, the stainless sheet didn't cost a lot more than the galvanised mild steel.
The only problem so far has been that I used polished stainless (mirror finish, came with a plastic protective film), thinking it would look pretty flash for a while, but the light refection was so bad that it impeded the video recordings.
I have now fixed this by scuffing it all over with fine sandpaper.

On the question of wedges/wedglets, I would have thought they are as basic to most combat bots as carrying a gun is for a soldier, and should be accepted as a natural component.
So, to the most effective wedge developer should go the spoils.

Mike.

[minionhunter]

Other things to think about

1. How are you going to transport this beast?
Can you disassemble it easily and set it up easily?
If keeping it in one piece, can you easily fit it in your vehicle?
Peter designed his to perfectly fit into his car.

How much is this thing going to weigh? Every step up in wall thickness adds to the weight of the arena (this will factor in transportation and storage).
How and where are you going to store this? These things take up space no matter where you put them, especially if always assembled. If you are putting it in a basement or other dusty area, make sure you have a sheet to cover it and protect the polycarb. If you are disassembling it, how are you protecting the polycarb during storage and transport? If disassembling it how much to the panels weigh and will they fit into your vehicle?

2. Arenas to think about
Peter Waller's (likely best overall, at least it is IMHO)
Chris Malton's (Posh, large, expensive, did I mention large and expensive?, it is really cool)
BBB (Waller clone with flap entry, slightly smaller, air ram hazard)
Ant Freeze arena
IPO's arena (stainless floor)
ARC in Australia arena (cool lights and trapdoors that open on trigger, but no pits)
Team Just Cuz Robotics arena plans from YT video

There is an arena build guide around somewhere, US site, that describes from tiny to battlebots sized.

3. You asked about size. My notes on size:
Think about the size of the panels and the size of commonly available sheets of polycarbonate. Since these are ants you are fighting you don't want it too large and you don't want it too small. So if you can get at least two of your sides to be the small dimension of a sheet, you can save yourself money and use one sheet for two ends, instead of needing to buy a sheet for each side. So in the US if the size is 4'x8' can you get the ends to be 4' (48") so that you can make two ends from one sheet of polycarb? This should save you some money.

Some reference sizes
Chris Malton's
1500x1500x750mm
stage 1290x1067mm (estimated based on YT, could be a little bigger)
Peter Waller's
1290x980x600mm (estimated height based on his drawings)
stage 1260x960mm

If using prefab aluminum pieces like 80/20 can the polycarb "float" in the pieces (not be solidly fixed) so that can take up more kinetic energy from the hits to it. You might think you want to have it rock solid like window glass, but since it is supposed to absorb hits, you want the KE dispersed as much as possible and loose fitted will be better than solidly fixed (you want the rattle). [PLEASE ANYONE correct me if I'm wrong about this, I've read it multiple places, but it could be wrong.]
If sliding doors, make sure you get the grooved channels for the floor so it slides easier (less contact so less friction)

4. How will you secure the floor to the arena? Some designs no brainer, but others will require thought.
Corollary, will it have legs? Do you want short or long legs? Will they have casters? Will you sit it on a table or two tables or stand it totally on it's own legs?

5. Learn from others and remember the arenas that work, they might not be your ideal design, but there is a reason why they have been around for a long time and are frequently used. Do you want a simple one that you can get through doors easily and into your car? Do you want a heavy one that requires a couple of people to transport the parts and you have to set up each time?

[minionhunter]

More thoughts.

Make sure you know which doors your arena will fit through. Don't think standard doors are an option unless it is disassembled....

Ant Freeze arena I forgot this one in my original list (I'm working off the top of my head)

Sacrificial walls - make sure you protect the lower 4" of the arena box by having sacrificial poly walls that take the brunt of the damage and can be cheaply replaced frequently (to avoid replacing the expensive large thick sheets frequently).

Also, think about your pits.

AWS rules require X% of surface area of Y total be open/pits which is a significant chunk of the sides.

The Malton arena deals with this differently than Waller arena.

The Malton arena has open ledges for most of the long sides, but also high walls that can be flipped over and out. This is a standard approach, but is very perilous and easy to push bots out.

The Ant Freeze arena has pits like the Waller arena but they are square and until recently (I think) they didn't have the 1" tabs. For whatever reason it seems like this results in quicker push outs than the curved pits. Maybe the sharp angles create more falls than the smooth curves?

The Waller arena (very cleverly) deals with this by having curved open pits. Two pits have a low 1" wall which represents a small barrier to being run out, the other two opposite pits are completely open, but have 1" tabs which prevent bots from being driven into the main wall then pushed into the pit (which can be far to easy/difficult to recover from). The 1" tabs allow similar strategy but it is not instant death, there is slight protection but not much. It is enough to make it competitive and not an instantly over fight. The convex pits allow maximizing the surface area for push outs, while not taking up precious wall space. For whatever reason, this seems to work really well (balanced between enough space to push bots out, and not taking up so much perimeter with open pits). It also does not have a "moat" around it, so bots which are flipped into the air will land back in the arena or a pit, they aren't immediately out.

The Waller arena is deceptively clever in many mechanisms. There is SO MUCH goodness packed into that design it is difficult to capture it all.

[Ocracoke]

Surprised the BotFest arena doesn't get a mention here.

4mm is the minimum thickness as alluded to and yes, something like 20 or 30mm wide/6mm thick polycarb for sacrificial walls would help. The BotFest arena collapses, that is all held together with 8x M5 bolts and the floor sits in between the uprights and a pair of pins at the front with a 15mm MDF floor at the moment. Originally, the arena had a completely open side to the pit but in BotFest 4, this was changed to have a low (~25mm) wall covering about 2/3rds of that opening. There was also the gap at the back end which was filled in due to popular demand.

The arena is light, much lighter than a fully assembled arena. I had to make the arena capable of being dismantled for storage and for transport (I use a 2001 Smart CDi 450 as my robotics transport these days). The headache is the roof which just sits there which is not ideal. That will be changed in a future version where it is cut to side and have removable hinges on one side so it opens up and can be locked properly. Floor size is 810mm x 810mm square.

[MySolderIsOlder]

Personally I'm a huge fan of the low wall options. They greatly reduce the chance of accidental drive-offs but still allow flippers, spinners, and even a well-driven wedge to knock their opponent over the edge.

[minionhunter]

Surprised the BotFest arena doesn't get a mention here.

4mm is the minimum thickness as alluded to and yes, something like 20 or 30mm wide/6mm thick polycarb for sacrificial walls would help. The BotFest arena collapses, that is all held together with 8x M5 bolts and the floor sits in between the uprights and a pair of pins at the front with a 15mm MDF floor at the moment. Originally, the arena had a completely open side to the pit but in BotFest 4, this was changed to have a low (~25mm) wall covering about 2/3rds of that opening. There was also the gap at the back end which was filled in due to popular demand.

The arena is light, much lighter than a fully assembled arena. I had to make the arena capable of being dismantled for storage and for transport (I use a 2001 Smart CDi 450 as my robotics transport these days). The headache is the roof which just sits there which is not ideal. That will be changed in a future version where it is cut to side and have removable hinges on one side so it opens up and can be locked properly. Floor size is 810mm x 810mm square.

Can you please post a link or two to videos of BotFest. I haven't seen this arena and would like to. Maybe it is because I'm in the US or maybe I'm not using the right keywords, but I can't find it.