Leveling of fields

How about using plywood?
Laying some thin sheets of plywood on the floor below the foam tiles?

It should be cheap enough. But it might be a problem for transporting though.


Plywood can get really warped, especially with transporting (and often even starts a bit warped).

Has anyone tested the cubes for angling issues? When we first took them out of the box, the team was stacking them up crazy high and carrying them around and I thought they stayed together surprisingly well. It might be that the angle has to be much steeper than the typical 1" allowance to make a big difference? If fields were off significantly over that, I’d definitely be considering questioning the local RECF rep. 4"?!? Crazy!


I think the field would actually have to be way over the 1” tolerance to have a major effect on stacking.

I’m surprised no one has responded to this yet. 4 degrees would mean one side of the field was a full 10 inches lower than the other. Unless you were outside in a parking lot or grass field that seems rather unlikely. What venue was this?


Skyrise was also the first year at worlds which they used the new field risers from IFMI, instead of the old designs Paul released to the public. The way they are built it would be almost impossible to be that far off, the field would have holes because the plates would be completely missing the gravity holding points.

@Dave_Flowerday I was sleeping, you beat me to it…

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This problem occured in Skyrise with team 62A. They had a killer 7 skyrise section auton that would have guaranteed them worlds finalists. At home on their flat floor they had it working consistently and even had a backup 6 section auton if something were to happen.

Despite their amazing robot, programming, and general preparedness the raised fields at worlds became a huge obstacle. The weight of skyrise robots was enough to tilt the field slightly where no supports were present and made them miss most every skyrise section in auton and struggle to stack in driver.

Unlevel fields are a huge issue to say the least.

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done a quick, basic test…

This is at 1" - max tolerance limit.

And we loaded the cubes manually, one by one and also as an entire stack - the results are similar.
(But do note that I believe robot doing the stacking will probably fair worse than manual stacking).

And this is at 1" tolerance limit, and the situation when it was 5 cubes high.
The stack toppled at 6-cube high.


We then moved it up to 1.5"… just half an inch above the limit, and the highest stack dropped to 4-cube high.


You’re right- I just did the math and got 10.07" which seems really extreme. It’s fully possible their measuring instruments were off or that only a small part of the field was tilted this much. I also remember him saying nearly 4 degrees so it would have been a little less extreme than we’re talking about. Still, you’re right, a consistent 4 degree tilt on a worlds field would have been taken care of.

Regardless of the exact amount of tilt, even tilt within the legal limit is a detriment to game-play, as Meng just demonstrated. How can we be sure the fields will be flat?


@meng’s demonstration is extreme, yes. Has anyone actually seen that in a competition? It looks like that setup is a 1" bump under one edge of a tile while the other edge is on the ground - i.e. 1" rise over 24". Such a bump would cause other issues with the field perimeter and such. I think if anyone saw that extreme of a condition they should politely ask the EP if it can be mitigated.

I don’t think you’re going to find conditions that bad in nearly any venue though. Most events are held in gymnasiums - which I believe typically have very level floors for basketball and such. Convention centers like Worlds have very flat concrete floors as well. If you have a specific concern about a field (especially at Worlds) the best thing to do is start asking questions. Maybe bring a level if you’re that concerned about it (but it has to be long enough to take decent measurements).

As for “how can we be sure the fields will be flat”? Well, at local events you could volunteer to help set up and ask to be put in charge of field leveling.

But first I’d start by identifying specific issues and measuring. It seems like so far this is all based on a “what-if” scenario rather than any real-world problem.


Nope. It is not over 1 tile.

I inserted a large piece of polycarbonate below the foam tiles.
Granted that it did not stretch all the way to the centre of the field (I didn’t have such a large sheet), but it went about 3 tiles in.

Let’s call a spade a spade, tilted field will definitely affects game play, and some games will be affected more than others, eg. Skyrise vs starstruck.

But still, as Long as it is within the specified +/- 1”, I really think teams can’t complain about that.

I mean, teams will need to design their robots and plan their gameplay within the expected tolerance limit.
But anything more than the specific limits will be unfair to the teams.

Edit: think the zoom-in view (I.e. 1st pic) makes it looked extreme, but when looking at the 2nd pic, the tilt is not exactly noticeable. And the stacked cubes actually slowly slided off. It took a while for the cubes to reach equilibrium positions.
So it was definitely not an extreme tilt.

But that said, if we are looking at max limit, think it is not wrong to look at 1” rise over 24” (1 tile) as well.


What I have found is the ANSI building standard for a level floor in the US is 0.25 inches (6.35 mm) over ten feet (3 m) which is 0.12 degrees. If a field had a 1 inch variation between parallel walls then the angle would be 0.4 degrees. Even in that situation the bubble on a construction level would still show between the lines.

It would have to be a very poorly constructed surface for it to play a significant role in block stacking.


Well, we’re way down in the weeds now regarding what “1 inch tolerance” means with respect to the field being level. I doubt anyone official has really thought it through specifically in that context. Without any further official clarification, I would take it as “no more than 1” rise over the length of the field", hence 0.4 degrees as @Hudsonville_Robotics said.

Your demonstration is 1" rise over significantly less than the full field width, meaning if the whole floor was tilted that much it would be more than 1" over the length of the field which I would say was out of spec. But again like @Hudsonville_Robotics said I doubt you’d find any venue floor sloped that much.

But, then there’s the question of bumps and whatnot. I have no idea how to compare those to the “1 inch tolerance” spec.

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Well… my initial idea of maximum tilt was based on one side of the field +1”, and the other side -1”.
This will give a 1” rise over half of the playing field.

But it just occured to me (I.e in the previous post) that this is not extreme.
Like you mentioned, the bumps and humps will be the true test of maximum tolerance limit.

So I would say that the maximum tilt within tolerance limit will be like having a 1” bump with the edge of the field resting on it - so that will be similar to having a 1” rise over 1 tile? Agree?

Of course you can argue that it is unlikely to find a 1” bump on the floor, but we are talking about extreme tilt within tolerance limit.

Anyway, the original intent of my post is to raise the awareness of how extreme tilt can affects this game, and so that EPs will take note of it during setup and teams will design and plan accordingly.

I would rather EPs have these awareness than to just brush this issue aside.


I think a steeper tilt could be achieved while still staying ‘within the 1” tolerance’:

If the center of the field were 1” above the reference plane, and a point in the center of one edge was 1” below the reference plane, then that would create a rise of 2 inches over 6 feet, or ~1.6 degrees of tilt.

But I think this particular geometry is pretty unlikely to appear in any environment where VRC fields are likely to be set up.

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You are right.
This will give an even greater tilt.

Oh well… think we just need the EPs to be aware and choose an as flat as possible area to lay the fields :slight_smile:


So you must adapt your strategy. Expecting volunteers to level a floor is just outrageous. If nothing else consider it a life lesson that some days suck. Guess what?? There will be far worse things in life then a lost game. Besides, you CAN adjust strategy.

Maybe you have not read all my earlier posts…
So let me said it again - i am all for students learning how to deal with real life situations, etc.
So yes… they should plan and design their robots and strategise with the +/- 1" tolerance limit in mind.

But if the field setup is beyond the tolerance limit, then i will be concerned if the EPs still choose not to do anything about it.
And as many has stated, it has to be very drastic to go beyond this limit.

And no… i am not a competitor, just an ex-competitor/mentor/teacher/sometimes EP that has been involved in robotics for the past… 20+ years.
So i do think i know what is too demanding and what is unfair to both the EPs and students.


I’ve been an EP for years, and supported many new and veteran EPs at their events. In my experience it is normal for an EP to try to make the fields as close to spec as possible, with our RSM doing his part to fix issues as the come up. The ±1" tolerance is a catch-all to deal with variations that come up due to all sorts of things, but I mostly see it as a safety net to make sure that the natural movement of things during matches doesn’t throw a field out of spec and question the validity of a match. The goal is always to set up a field as close to perfect as possible and make adjustments as needed throughout the event. I for one, and I don’t think I am unique among EPs, would not be satisfied with seeing a field that is 1" out of level at any event I ran or helped with.

All that being said, while not directly a “level” issue, I am wondering if the stability/rigidity of raised play surfaces is going to become an issue, especially with the REC pushing for raised fields at Championship and Signature events. I could see a bigger issue than a non-level field is a field that has too much give due to using unsupported 3/8 plywood over a 4’ span or something similar. The raised fields we will use at events will almost certainly be rented commercial staging, but I could see circumstances where the least expensive solution is deployed and it ends up being pretty bad. It’s already been discussed that a cube can be dislodged from a high tower by hitting the pole - imagine a field with enough floor flex that a robot simply driving away from a tower bends the field surface enough to have the cube fall out. Or a goal zone flexes and a nice stack of cubes falls.


I agree

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