Adjustable hood vs dual flywheels on a shooter

Our team is currently deciding to use either an adjustable hood or 2 independently powered flywheels. What are the pros and cons of each?

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Each are of course great in their own right. Independently powered flywheels will give you less versatility in your adjustment for each shot, since the only thing you can change is the speed and spin at which the ball exits the shooter, so you get a good amount of adjustment for a small to medium range of super fine tuned shots. Whereas with an adjustable hood you have the option to design it to make every shot possible on the field, fender to launchpad to HP station and all in between.

There is always of course the case of resources as well, adjustable hoods are an investment of not only money, but as well programming. That is if nothing else, a lot of effort that someone has to put in to get it functioning to its full capacity. Just be sure your entire team is up for making one or the other.

Both have some great cad examples out there already, from this year I’d suggest looking at 1678’s for an adj hood, and for 2 independently powered flywheels I’ll be lazy and use a friend of mine’s cad for an offseason bot.

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Why not an adjustable dual flywheel shooter?

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I’d say complexity is a pretty big reason.

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Catapult, on a turret, but the catapult launches 10 inches into a independently powered flywheel shooter with an adjustable hood.

Ignore Complexity. Embrace Absurdity.

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image

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Yep.

In our experience, go with a hood first. There are loads of ways to construct adjustable hoods, each with their own benefits. The biggest deal with hood is that really only recently did it become more relevant to have control of the direction and magnitude of spin on a ball, which necessitates having dual rollers. Hoods are much more versatile and do a good job in most any other shooting game. Only start worrying about dual rollers if your complexity budget allows for it.

Follow the KISS principle - keep it simple. We’ve used a hooded shooter for Rapid React and Infinite Recharge. During this offseason we are exploring an adjustable hood. We are using pneumatics and having only two positions on the hood. We’ve seen some amazing teams (2056) be incredibly successful with a similar strategy. We’ve also seen teams with infinitely adjustable hoods struggle. Taking the time to test and adjust is crucial. Good luck!

I like 2 wheel shooters. Like this one

Here is a video of a bench test shooting

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This one has elevation and works as an intake and shooter. The azimuth you get by turning the robot left or right but no reason why you couldnt mount it on a turret. Max distance in the current config is about 40 feet to hit into the upper hub so you should hit it from anywhere on the field even in less than optimal conditions like something binding or low battery

C shooters - to shoot you need to compress the ball after it leaves the wheel it decompresses and bounces away from the wall it was compressed against So the inflation level (which you dont control) of the ball will influence its trajectory. Now a 2 wheel shooter compresses too but on both sides 100% equally so the ball will come out straight as to the center of the 2 shooting wheels.

With this system in past years we did cross court (alliance wall to alliance wall) shots (in games where it was allowed). As they are very predictable (free fall formula) programming is quite easy. its just using the physics formulas times a factor (<1) to account for mechanical loss due to friction etc. You also have the benefit of having the power of both motors

Here is a little video from the 2019 edition
Targetpractice_s

As you can see in this test the direction was accurate and there only was a slight degradation between shots which was/is easily fixed by feeding the balls a little slower to allow the motor some recovery time to get back up to rpm

Aiming in the past was usually done with a camera and with a cross hair drawn on something with adjustments for elevation for distance - kinda like on a gun telescope. So low tech - no programming. This particular shooter was fixed angle and distance was changed by changing the rpm

Unfortunately this one never saw live action due to COVID

From personal experience, it can be difficult to get consistent results using dual independently powered flywheels, even with a well-tuned PID. Adjustable hoods provide far more accuracy and consistency and are relatively simple to make work well. Also, as others have pointed out, you tend to have far less shot variability using dual independently powered flywheels than you do with an adjustable hood.

I’ll also second the suggestions dual-wheel adjustable hoods, at least for games like this years where eliminating backspin is important (in 2020/2021 it didn’t matter as much), though I personally prefer both wheels to be driven from the same motors to ensure consistent speeds between the wheels.

Did you find all that mass on the top wheel necessary or do you think you could have gotten away with less?

It was needed to get accurate speed regulation. I agree the better approach would have been a single motor to drive both upper and lower wheels; reduced flywheel inertia/mass would have been among the benefits. However, adjusting both hood orientation and upper wheel speed independently was seen as a potential advantage. We had accurate shots from all ranges, when everything was working.

Complexity.

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