I have heard stories that some groups of people have found that power cells don’t react well when rolling against other power cells (particularly with some sort of moving belt on one side and a static floor on the other). We have been unable to test this ourselves since we are still waiting for our order of power cells to arrive but it is pretty critical to design so I’m curious if those who have multiple Power Cells (the real deal, not the off-brand ones) and have tested this would be willing to share some insight on their experiences with this situation.
Tagging @Ben_Martin and @Connor_McBride because iirc Team Capital had a similar setup and would love to hear if they ever had problems similar to the ones described.
Yeah the’re probably the worst game piece I’ve ever experienced when interacting with other game pieces – they are extremely sticky against each other and quickly compress into tight spaces. We quite literally had a game piece stuff itself in a <2" space between a powered roller and idler roller. Check out our early videos, several of them highlight this issue.
Also pinging @anon24941552 and @SJaladi because they spent a ton of time with this system.
Would highly suggest teams do what they can to make the game pieces not touch each other when indexing them.
Yes. They are bad. Worse than the 2012 basketballs - and I thought those were pretty bad. If you have rolling contact between balls in your system, it’s likely you’ll have problems. If you’re trying to ‘consolidate’ rows of balls into a single row to your shooter - you’re likely to have problems. They are sticky enough that if they come in sideways to a urethane belt they will happily push the belt right off the pulley. Like on an intake.
Be very careful. They will stick to anything they rub on while moving.
I think this will bite a lot of people.
Also note - these things absolutely LOVE to roll under your robot as you drive forward. Watch videos of 2016 to see what happens after that.
We were able to get every other subsystem working on our Ri3D in between 1-5 iterations. The intake that brought the balls into the robot in a single file line took 50+ (with maybe 25 being rapid micro iterations like same dimensions with different wheels). We pulled our hair out on this one.
Any time you’re rolling the ball through spaces on your robot, such as rolling the ball with belting on one side and polycarb on another, you’re liable to jam. That rolling action immediately stops when two balls come into contact because of their surface texture.
The best example I can make is meshing two spur gears and trying to spin them both clockwise.
If you’re trying to center a ball at all, make sure the ball is centered before it contacts your polycord/polybelt/conveyor run. The balls will pull any of this (except maybe timing belts? we did not test) off their track. We had to switch to “hot dog rollers” on our intake because it was too close to our vectored intake wheels to use polybelt like in the rest of the system.
Highly recommend not using urethane belt anywhere you’re centering a ball. Highly recommend transmitting power with belts on TWO sides of a ball so they don’t ever rotate inside your robot.
In that case, you want the ball to stick to the bumper. It will help the ball to climb up and over as it rolls, as opposed to just spinning in place against the bumper. You might want to look into a chin bar - a bar attached to your intake going across just below the bumper. This will promote the ball going up rather than under
If two balls contact each other in a double-conveyor system (contact on both sides, no rolling), does a similar problem occur, or does the lack of rolling mitigate the issue?
I was being “bad mentor” this week, and every time we got to discussing how balls might move through the robot, or a pickup mechanism, and someone suggested an angled plate or something to move them sideways, I said “it won’t work”.
I’m generally in the camp of “letting students fail in order to learn something” when it doesn’t make a major impact on their competitive success/budget/happiness in the program.
I do not think learning how to manipulate these balls from scratch has any learnable lessons worth the headache. Sarath and I will be taking what we learned at FIRST Capital Ri3D and directly teaching our students our lessons learned. There are plenty of other challenges in this game for them to own from ideation to execution. Ball manipulation they can just own the execution.
This is the worst game piece in any game I have ever played.
We received a bunch of the balls today so we played with them during the brainstorming meeting. Several of us tried rolling one ball while gently pushing a second one against the first. In all cases, the second ball acted like a brake on the first ball and prevented it from rolling.
We concluded it was not worth prototyping any sort of ball transport mechanism with a belt on only one side.
I was watching Kettering’s Ri3d and it didn’t look like they were having issues with them sticking together with a one sided roller. Granted, not a lot of video and possible video production. I wonder if it had anything to do with them rolling on PVC tubes nad not on a flat surface. One sided would be nice but don’t want to risk the problems.
My guess is they were careful to space the balls out as they pulled them into the conveyor. Something that can easily be done on a controlled practice or video, but not so easy in a match.
