Cheesecaking a Defensive Robot

Is there anything against the rules for adding parts onto a robot to block shots? For example, adding chains so the ball hits it and falls down, something like that which shouldn’t violate rules regarding blocking vision tracking. We are thinking about bringing parts to cheesecake our third alliance partner (assuming we are a captain again), and want to make sure there is nothing against the rules for adding a blocking attachment to a breaching style robot.

Our alliance 2122 & 125 decided to add some rails and fabric to our robot for the finals at Arizona North regional to try and block the vision tracking of our opponent. Its didn’t work well but we did have to get re inspected and re weighed before returning to the field.

Essentially, as long as it either fits within some team’s 30 pound withholding allowance or is built in the pits (or official machine shop) during the competition from COTS parts and doesn’t break any other rules (e.g. having mercury), it’s OK; see sentences I emphasized in R18 below. As noted above, the receiving robot will have to be reinspected (and more specifically re-weighed).


Here’s another example of not meeting another rule. If the rails and fabric were intended to block vision tracking, they would have violated R9, particularly as amplified in Q953. If they were intended to block shots and just happened to block vision, that would be OK.

We cheesecaked our 3rd alliance member in playoffs at both Sacramento and Central Valley Regionals.

Out of 1678’s 12 playoff matches to-date, our opponents have only captured the tower a total of once. We’ve had fantastic 3rd alliance members in 3970 and 5274 that have contributed many points to our win margin through solid defense.

Defense, when played right, can be brutal. Many top-scoring teams can be shut down by some solid cheesecake.


Famous last words!

Okay, thank you for the help! I was either thinking of creating a kit that we could cut up and use that (so it doesn’t count as withholding) that either contains a t shape of aluminum with chains hanging, or a sheet of lexan.

Lexan seems more viable to me since the amount of robots with enough spare weight to add a lexan shield on top seem to greatly exceed the amount of robots with enough spare weight for a metal chain setup. Good luck, in any case, with your defensive cheesecaking endeavors!

If you’re going to use chains, make sure that they don’t have the ability to go beyond the 15" extension limit.

Be very careful when you design said kit so that it is purely COTS pieces that are to be modified on site. This means in your case, it would have to be a full rectangular sheet of aluminum or lexan that you would cut into a T shape, unless you can provide documentation of a place that regularly stocks precut T shaped sheets.

So I wouldn’t be able to bring like a 5ft piece of aluminum then cut it down to like 3ft and 2ft? It may be worth it to drill a bunch of holes into the lexan to cut down the weight even more.

You can cut and drill into it all you want, you just have to do that on-site and on-the-weekend-of. You can bring in all the COTS materials you can fit into your pit, but that’s the rub - it’s all COTS. By technical definition, once a product is past “[an] unaltered, unmodified state [from point of purchase],” it’s no longer a COTS part and would be part of your withholding allowance. Arguably, no one is going to ask for an invoice for each piece of metal you brought in, but if it’s obviously already been cut you might be inviting a few questions from an RI.

If you can find a place where you can purchase a 5 ft piece of aluminum, you’re golden in the situation you describe (assuming the holes are drilled at competitiion).

We (and many other teams as I understand it) bring in “random” lengths and areas of various metal and other material stock that are left over from previous construction. Our general rule as a team is that all cuts on these items shall be square (no bevel or miter cuts) and that nothing shall be cut to a length that is meaningful on our robot. (E.g. if we have arms made of 29" lengths of 1"x1" aluminum, a 29" length is a “fabricated” length, and a 33" length is a “random” length. However, if our arms were 33" long, the reverse would probably be true.) While this may stretch the letter of the rules a bit, we feel it honors the full spirit of the rules, in that we must do just as much cutting on the COTS items we bring in as if they really were “full size” COTS parts.

As it turns out, very little of our metal stock is delivered to our workshop in entirely “COTS as we bought it” condition. Apart from our Versaframe, we get most of our angle and c-channel from a local company (Bayou Metals) that sells in 20 foot lengths; we usually carry it the two or three miles to our workshop in roughly 10 foot lengths, because it is carried on top of an SUV or small pickup that is only about 14-16 feet long.

If you want to be really strict on this, cut your “random” pieces to multiples of 12", and you can almost certainly justify your pieces to be COTS-equivalent as available from or a similar website.

The common way of doing it is to design your cheesecake using something like VersaFrame that can then be assembled with COTS fasteners. This means that, when you get to the competition, you simply must drill the holes (if you used any that aren’t already drilled, an advantage of the VersaFrame is that it already has many holes that may be used for mounting) and cut the pieces to length before assembling it as desired.

Actually there is a blue box in section 4.1 of the game manual that specifically deals with items that are neither COTS nor fabricated parts and the example is a 20 foot piece of raw material that has been cut to 5 foot lengths for ease of transport.

Use last year’s pool noodles (the ones you didn’t stick in your bumpers). And plenty of duct tape. Just make sure that you go through inspection with them on.

No, I’m not joking. 1452 sprouted a full head of green (pool noodle) hair between L.A. Finals 1 and L.A. Finals 2. Blocked a few shots… and that wasn’t the part that failed when they needed it most.

So the weekend of Greater Toronto Regional East, my team was hosting a public Raspberry Pi robotics workshop at our local library. Toward the end we gave a quick demo of our FRC robot. Meanwhile, the live stream from GTRE was running on a projector on the other side of the room.

While everyone was watching our demo, I saw that a finals match had just started. I shushed the crowd and said “everyone please turn around and look behind you, this is a live competition match happening right now!”

Everyone turned around - JUST in time to catch a close up of 3710’s robot drive by - complete with a blocker made of a clear bag draped over its “head” and a giant angry-smiley face made of tape!

My team was actually just looking at that last night, we were trying to find video proof to show our Coach that we are able to cheesecake partners.

Thank you all for the help! I think I understand what I can do better to get parts ready for defensive cheescaking.

It appears that some robots have already been “cheesecaked”…literally.