Was there a reason the two flywheel / two wheel design was not very popular last year?

Our team is looking at developing a new flywheel shooter for the at home challenges is there any reason we should avoid the two wheel design? From the view videos we found of it last year some teams seamed get them to work well. How ever it seams that the majority of the teams decided to go with the single wheel design. What made your team go with one design over the other?

What design did your team chose
  • Single Flywheel
  • Dual Flywheel
  • Low port only
  • Other

0 voters

2 Likes

We experimented with a two wheeled design early on in the season and we found that it was just less consistent than a one wheeled shooter without any noticeable benefits.

3 Likes

Extra moving parts, weight and robot real estate not required to meet the game challenge

7 Likes

Nobody built dual-turret robots in 2017, either.

Nope.

But in all seriousness, less complexity in design tends to leads towards more effective and consistent robots.

2 Likes

Did you mean a particular kind of “two wheels”? We saw a few teams with two wheels – one on each side of the ball. And we had two side-by-side wheels on our hooded shooter. We were initially unsure how much width we would need due to ball compression, and it seemed to work well so we left it that way.

2 Likes

To keep the balls from bouncing out, you want a lot of backspin. A single-wheeled hood shooter provides that backspin.

Fewer parts, less complexity, more desired outcome = no-brainer[ish] choice.

3 Likes

I was talking about something similar to 971’s 2016 robot where the ball is propelled by both sides instead of one wheel and dragged along a hood

3 Likes

Oops, then I voted wrong, sorry,

2 Likes

The biggest thing for our team is that we found that the single wheel shooters added backspin to the ball, increasing stability and accuracy when in the air.

7 Likes

The main reason they did that way is probably packaging, as a double flywheels shooter has a lower profile, but is wider, this year you could fit a hooded shooter without much problem even in a lowbot
(we did a double flywheel tho https://grabcad.com/library/bs-04-2)

2 Likes

No I think most people did it because it is easier to get working “good enough” (minimal tuning/repeatability needed) and the backspin is advantageous. I saw robots that used a double wheeled shooter that produced minimal spin and the balls were hitting the back of the upper port and bouncing out.

1 Like

Standard reminder that this poll will be biased and not a great representation of the “average” FRC team.

14 Likes

Also there’s a distinction between vertical dual wheel and horizontal dual wheel that is missing from the poll.

17 Likes

I would also add that historically for every past small ball shooting game (2006, 2009, 2012, 2016, 2017 and 2020) the single flywheel shooter is by far the most prevalent type of shooter due to the aforementioned themes in simplicity and backspin. There are also many examples of top tier robots which used this design in each of those games.

Suffice it to say, the two flywheel design has not been “very” popular any year.

11 Likes

3309 used a double flywheel for our 2020 season with … mixed results.

Some of our matches:
Successfully shooting three consecutive powercells into the high goal from behind the control panel (but failing a few other attempts to do so): Qualification 58 - 2020 Los Angeles North Regional - YouTube
Shooting some powercells from right in front of the power port: Qualification 10 - 2020 Los Angeles North Regional - YouTube

We did not suffer too many problems with the flywheel itself. Most of the issues we had with the shooter were either with software or other subsystems. We had no vision code, the power cell conveyor/indexer slipped a lot (which is why we only scored one preload in auto of match 10), and the arm had a lot of backlash (you can see it jiggle around in the matches). Those factors are what made our 2020 shooter miss a lot, so I do not think you should judge all double flywheels based on our robot.

It is also worth mentioning that our unorthodox robot design lent itself to a double flywheel and that backspin (or topspin!) can be adjusted slightly if the top and bottom flywheels are controlled by different motors.

3 Likes

987 has a side-by-side dual, dual wheel shooter. It is beautiful. HIGHROLLERS - Team 987 (2020) - The Blue Alliance

3 Likes

Did your team test the horizontal arrangement of the two fly wheels or only the vertical arrangement? Our team viewed the vertical arrangement as most likely the most worth prototyping.

I think we tested both. The vertical orientation can control backspin and was easiest to integrate into our robot design, so we went with that.

2 Likes

Is there a location to find some pictures of 987’s shooter for 2020? I watched a couple of their matches and they looked impressive.

Thanks,

Kevin