Out team is trying to build a single flywheel shooter. Currently we are using a 4" colson performa wheel that is 2 inch wide. Despite Pid control and trying various compression, our shots are all over the place. Any suggestion on the wheel choice and the amount of compression that may improve our consistency will be greatly appreciated.
Thanks
Have you tried putting a second, identical wheel on the same axle? Or, how about splitting the 2" wheel into two 1" wheels? The resulting “groove” should allow a straighter track through the shooter. It’s not an uncommon setup for FRC shooters.
Thanks for the suggestion. We will try that tomorrow.
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Colson’s are too hard this year. Try a soft rubber wheel for your flywheel.
We are starting to think along those line too. I think my team build a reasonably good cage and hood for the flywheel and we have done everything we knew to tweak it. We will look at a softer wheel.
I really want to see slow motion footage of a ball leaving a shooter that has a soft rubber wheel. I’d guess that at the speed the shooter wheel spins at, there is enough centripetal force pulling outward on the wheel that it acts like a hard rubber wheel rather than a soft one.
Try rolling the balls through the shooter by hand, putting them in the bottom and spinning the wheel with the robot powered off. This is a pretty subjective and variable thing, but you want the ball to resist going through somewhat without really getting stuck or sliding by freely. (There also should not be one spot early in the ball’s path that is much tighter than elsewhere.) This is a rough indication of whether you have a dearth or excess of compression. If you have too little compression, some balls will probably not catch well and receive less energy than others. Conversely, if you have too much compression, the aggressive deformation the balls are undergoing can make their trajectories hard to predict upon exit.
The equalizing factor, as Clint said, may well be trying a softer wheel that allows more compression to come from the forgiving wheel rather than the balls.
The flywheel has to grab the fuel consistently and bring it into the shooting mechanism, the colsons slip a lot before actually taking the fuel into the shooting mechanism, resulting in inconsistent velocity and distance.
YMMV, just some results from our tests.
Which wheel will you recommend?
The new andymark wheels.
Space and weight allowing, more massive flywheels can be more easily regulated using PID. Through conservation of momentum, a large mass flywheel will transfer less of its momentum to the fuel than a less massive flywheel for each shot. It will take longer to reach optimal shooting angular velocity, but will maintain that angular velocity much more easily. If it’s possible you may look into that in addition to different wheel surfaces
Just for clarity, I assume Anthony is referring to these, as well as the other compliant wheels AndyMark has released this past season.
To the OP, a picture of your current setup would help us all dig into the minutia of your design and offer advice, if you so choose.
Not much has changed, really.
This is why I love the** laws of physics**. Everyone has to obey them all the time. They don’t care who has been elected police commissioner, president, or dogcatcher.
Our initial prototype used the 4" traction wheels that have come in the KoP in the past (very hard). It worked well enough, but even with only a moderate amount of compression you could hear/see the CIM motor powering it practically stall when a ball went through. Switch that out to the AndyMark compliant wheels, and now with the same setup (same compression, same motor, same gear ratio, literally the only difference is changing one 4" wheel for another) we can feed in a whole row of balls without any noticeable slowdown with the motor. The compliant wheels really do make a difference.
Two banebots blue wheels, 3-7/8", seem to have good inertia. And they grip well. Only issue is the already talked about “film” build up on the wheels after shooting a lot of fuel.
Varying the compression even an eighth of an inch had a big impact, so make sure you’re not using a narrow flywheel. The holes in the fuel will ruin all your planning.
This is what we are using. https://www.mcmaster.com/#2497k16/=16a565k
Or conversely, not enough compression mixed with small wheels will be ruined by the holes.
Didn’t realize there are two type of 4"wheel with 50a durometer
I order the stealth wheel and then see people talking about the compliant wheel.
Does anybody know how different they are
Should I buy the compliant wheel instead
There is a world of difference. The stealth wheels, while great for quick intakes and grippiness, have a lower moment of inertia and are not at all compliant. I would not suggest using stealth wheels as your shooter wheels.