Shooter inconsistency due to worn-out power cells

While prototyping we noticed a difficult problem. After agressive shooting, or being crushed by drivetrains(should happen pretty often) the “skin” of power cells would start to disconnect from the foam insides. For ease of visualization we call these power cells “plasmolyzed”. image
While our shooter prototype is very consistent when shooting the same ball, new balls and “plasmolyzed” balls shoot quite differently,enough to miss the 3-point goal. The new balls would always fly a bit shorter. If this is a common issue, then shooting consistently could be very hard, assuming that "plasmolyzed“ balls wouldn’t be removed.
Has anyone else also experienced this and are there any solutions?

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We have noticed the same “Plasmolyzed” damage to our power cells, however don’t have enough data to tell if it has affected our shooters. It didn’t take us a lot of use for this damage to appear.

Do you mind sharing what kind of shooter setup you are using?

Not sure which prototype has been damaging the balls, perhaps a combination of both;

  • 2 wheels spinning around 4500RPM, feeding the ball between them.
  • 1 wheel pressing the wheel against a ramp as a hooded shooter (Same RPM).

How much “squish” are you using? I’m wondering now if we’ll see a “watch your squish” ruling soon…

If I recall correctly, somewhere between 0.5" - 1.0".

I volunteer as Field Reset and am attending a Week 1 event to volunteer. I will update, if I remember the give and takeness. I started volunteering 2018. For Deep Space, we had 3 rings to measure cargo size. One would be the perfect size, one would be max tolerance (inflation wise) and the other would be min tolerance. We didn’t really replace the balls because the worst ones would’ve popped. I’ll see what the tolerance is this year but plan to be adjustable and attempt to tolerate small differences. If you notice they have an issue, tell Field Reset and we’ll bring it to our Field Supervisor.

Are there any guidelines to replacing “plasmolyzed” balls? This type of damage seems to be a condition that is hard to quantify, unlike the size of cargo.

@Alan and @bsimmons does it matter if only part of the skin is disconnected or loose? Does the loose skin eventually tear?

Even if there are guidelines, it is likely that not all balls with loose skin would be replaced. For instance, the balls that are already on the storage racks at the loading station are likely to be left in place unless those guidelines require the field reset people to check them.

IIRC previously, unless field reset noticed, it was up to the teams to notice (or check without causing delay) that field elements were damaged before their match started.

For fear of damaging all our power cells too early, we opted to test less aggressively at this stage, so can’t say how much it actually affects our shooters, or how common further damage is.

Q&A has answered one question about how cells will be replaced:

I have no idea as Field Reset gets trained on the spot. I’ll need to see at my first competition (Durham College)

EDIT: Please see @scottgoering’s response (i.e. the Q&A link)

Our first power cell, received at kickoff, has a noticeably much higher compression level (hard) than any of the others we got later on. The shipment we got later the cells were more consistent.

You may need your HP to test and organize the power cells to give similar compression level cells to the long range bots and give the extra high and low compression cells to the close shooting bot.

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This won’t be such an issue for those teams who are only aiming for 2 points, I expect.

Thanks for confirming what I suspected would happen, based on experience with previous ball games.

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In a team update there was a clarification that the seal of the ball should be popped, so it vents air. Our KOP ball was much harder because it wasn’t venting. All of our balls from AM were consistent and vented air properly.

From a grumpy old timer who played Aim High: deal with it. The balls will be run over repeatedly. They’ll be sucked up and shot out by mechanisms that do all sorts of horrible things to them. By the end of a competition, their squishiness will change, they’ll be plasmolyzed, there will even be chunks missing from the occasional ball. (And we’ll not even going to talk about off-season events.) You might get to trade with your alliance partners so you can preload a few of the better ones, but otherwise you should just expect high variability and seriously sub-par balls on the field. Don’t expect FIRST to issue a ruling about how much you can squish a ball or provide tight tolerances on how the balls will behave. This uncertainty is part of the game.

The question is whether your shooter design can handle this variability. Anyone can spin up a flywheel and put balls in the air; the challenge is doing so reliably given highly variable conditions.


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