How Driver Skills can be Impacted based on Robot Design

This thread is mostly being made due to a side conversation that occurred in this post regarding how different robot styles can impact its efficiency in driver skils. I’m personally making this thread to help others understand as well regarding how an automated ejector can vary in strategy compared to more generic conveyor setup.


well in terms of skills, a pooper is undeniably better.
it allows you to discard the blue balls while you score the red ones, which saves time. and it also spits the blue balls behind your robot where they don’t get in the way of the red balls you need to aim for, which is especially good for prog skills.

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What is preventing you from simply running the conveyor more to discard the blue balls held within the robot? I can get the incentive to be able to discard the balls into a corner that will not be accessed by programming skills, but the same could be said for running a conveyor. There isn’t a reason to go back to the same goal twice.

If anything, a ball ejector should be more detrimental in skills due to the balls being forced out towards the center of the field. You could make the argument of simply turning around and ejecting the balls into the corner, but would that not be slower than cycling the conveyor again given its pointed in the same direction?

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So I guess lets use some math to calculate the time needed to cycle balls in each cases, I’ll be basing my math on a 270rpm base (5:3 200, 3.25") as this and 257rpm (3:7 600, 4") is probably going to be the most common speed this season. I’ll set the cycle time to about 1 seconds, which is what I see in most 600 rpm roller bots.

A robot will be about 18" in length. This along with the velocity of the balls from the roller will probably set the ball at about 40" away from the goal. The linear velocity of the 270 rpm robot will be 113.3 in/s, meaning it will take 0.35 seconds will travel from the ball to the goal. At this point the ball will already be 35% through the cycle, while the ball which wasn’t pooped haven’t been cycled yet, and will take another second to do so. The 0.35 second time save might not look significant, but if in late season teams start to implement 1800 rpm rollers, the ball will already be ready to score when they reach the goal, creating a huge time save.

The main advantage in this situation is that you can cycle balls while traversing the field, which saves cycle time when you reach the goal. To make this advantage as small as possible, you’ll want the ball to be as close to the goal as possible, meaning the most optimal position will be when the ball is zero inches away from the goal - when balls aren’t removed by the pooper

TL;DR - the Achilles heel for poopers is that it will poop opponent balls somewhat close to the goal. The team can literally come over and intake the ball, pre-index it while driving over, and instantly deposit it, creating a huge time save to own goals. You might be giving some free points to your opponent at the during the match, but you can gain an advantage while cycling and owning rows by doing so.


The ejector could always be tuned down to spit the balls out at a slow velocity. Even if the balls do reach the center, the robot can sort the difference between the types of balls.

I see your point though. If the balls move from their position then thats the problem, unless the robot can track them.

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look at these 2 different driver skills runs:

97963a has a pooper, 10955m does not.

I think its very safe to say that 10955m has a faster cycle time, but both skills runs are of the same length, just under a minute. you can see many moments in 10955m’s run where they have to stop and spit blue balls out the front, making sure they don’t get in the way of the red balls they need to go for next. 97963a is able to just poop while they score, which saves them a few seconds overall, allowing them to get an equal run to a robot that is faster but lacks a discarder.


This could be a possibility, but then the discarded ball would end up being right behind the robot. Say for instance you were cycling on a corner goal, the ball that would be discarded at a low velocity would end up right behind you. When moving away from the goal, the ball would come along with it, eventually ending up in the center of the field and potentially clogging up any pathways for heading towards other goals.

This is true, however, 10955m’s movements aren’t what I’m trying to get at. They were trying to spit out balls while turning and moving, resulting in them ending up near a side of their robot or in front of them. My vision for this method would instead be to drive backwards slightly and outtake then, allowing the balls to end up in front of the goal instead of in front of the robot.


also, there’s another option that isn’t being considered:
a pooper with a one ball hoarder.

this allows you to discard an opponent’s ball while not letting them access it immediately after.

and it just reduces the number of opponents balls by one, which isn’t a lot but it’s something.

also, notice how 97963a uses their pooper. not while they are at the goal, but rather as they collect balls for the next goal. you could do this in a match as well, in order to better disperse opponent balls and prolong the time they don’t have access to them.

and in terms of skills, this allows them to safely discard blue balls in a way that doesn’t interfere with red balls, which is handy in driver skills, and crucial in prog skills.

I think the difference is purely due to the strategy the teams use in the skill run. In the 10955M run, they chose to intake the ball then instantly discard the blue balls from the goal. What teams can do instead is either to discard blue balls while driving to the next goal, or do it along with intaking red balls: blue balls will be always be on top in a skills due to the nature of a snail bot.

It is still pretty early season, and teams are still trying to figure strategies out, it is probably possible to find a route which can make you discard blue balls while intaking red ones, which can make the difference between pooper and non pooper a lot smaller.


if you do that you’ll be chucking blue balls at the red balls you need to pick up. you have to turn away from your next destination to safely dispose of blue balls without a pooper, which will always slow you down.

This might just depend on intake design - we keep the balls in the rollers only and the intake can’t outtake balls by itself. Why not spin the rollers backward in this case and hit the blue balls out of the way.

if nothing else, a pooper definitely gives you some level of versatility while having no real downsides, so I don’t see any good reason to explicitly not build a pooper other than the slight added complexity. (but robots this year are so simple its really not an issue tbh)

I think poopers definitely provide more than just a little extra versatility, and I think they’re comparable to cube locks of last year. necessary? no. but advantageous, especially at high levels of play.


not sure I follow this, what do you mean?

Run the intakes in an reverse direction (outtake) so the front sprocket rollers can hit the ball away from you, meaning it will no longer be in the way

Personally speaking, I think both methods should be fairly viable for driver skills and programming. I can see the appeal now based on 97963A’s skills run alongside tweaks that can be made for 10955M’s skills run as well.

What I personally think will make the difference between both methods will be the intakes for gathering the balls themselves. In both videos the teams spend an especially long time to gather balls on the field, resulting in slower runs.

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This would be a good thing to write in the engineering notebook of a team building and finding the math behind each design.

I fail to understand how this would save you from having to face away from your destination for a second and discard blue balls. maybe I’m missing something, but I don’t see any way that a pooperless bot can be faster than one with a pooper in skills.

I can agree with this, intakes are very important. you need to be able to field balls as quickly as possible, and you need to be able to descore balls as fast as you can score them to keep up with your launcher’s cycle time.

To be fair, there have been fairly low public videos regarding skills runs on both designs.

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