My team got the idea of making a claw that ejects the ball with wheels around the centre. Is that even possible??
A great many things are possible. This is one of them.
Whether or not they are practical is another story. Some prototyping will help to determine whether they are practical–and many a team doesn’t like giving away prototyping ideas.
You’ll find out whether it’s possible one of two ways:
Do the relevant calculations regarding projectile motion and wheel speed, and compare.
Prototype it yourself and see.
As for how you’ll figure out whether it’s possible for your team, well, only you have those requirements.
Wheels around the center of a claw. Sounds enticing, if not a little vague, too.
Lots of catapults out there, I’m interested in seeing some wheeled shooters. In fact I might just get students to prototype this Saturday.
I would be worried about damaging the ball fabric. Since this is kind of a heavy and big piece to shoot with some high speed wheels, you’re gonna need something with enough inertia to not slow down too much while in contact with the ball during shooting. If you need something with a good amount of power to launch this ball more than 5 feet in the air, you might run into problems with damaging, or even tearing the fabric, which is against the rules, and the referees will have to address this during a match. We ran into this problem in 2012 with our shooter since the foam basketballs kept getting shredded up.
This is just my speculation, and I haven’t tested this, so take what I say with a grain of salt and don’t limit your possibilities. I say try it out if you think it’s worth doing, and you’ll have your answer soon enough.
taking ball damage and inertia into consideration, perhaps an hour-glass shaped roller, with a good mass would be better on each side rather than 2 wheels.
The asymmetrical nature of the ball is also an issue.
Lots of the 3 day robots had the intake with wheels, and team O-RYON used the wheels to also score in the low goal. They had another mechanism for the high goal. Wheels will work depending on what your goals are.
Hourglass roller would be more likely to damage a ball since the surface speed is different at the different diameters. So you’re guaranteed to have slip and scuffing.
Good point there
Just read this thread about ball damage. Caution will be the name of the game.
Launching the balls with wheels is very possible. Check out this video.
Are any teams not planning on shooting over truss or for high goal?
What we can’t see in the video is what those wheels are doing to the fabric of the ball.
…and damage to the balls is a FOUL (blue box for G10)
More than just TechHOUNDS have a working prototype for a wheeled shooter.
Here is a video from 2383 the Ninjineers and their design:
If you pause the video at about 18 seconds (close up of the ball), you can see some scuff marks but nothing more
Seems to me like a good way to approach the game
Scuffs from a high speed wheel shouldn’t be taken lightly.
Scuff marks in Ultimate Ascent turned into gouges in discs.
Scuff marks in Rebound Rumble turned into chunks of foam missing from basketballs.
That said, it still works really well as a directed shooter. I’d like to see some different wheels tested.
Yup, we are using a wheel shooter.
So far the ball hasn’t popped haha. We’re using plastic treaded wheels and have found that each tread kind of scuffs the ball. But I think this could be solved by a smooth wheel.
If the ball gets a lot more damage, we’ll try smooth wheels.
But all in all, wheels are a viable option!!
Be sure to read the blue box at the bottom of G10 regarding ball damage.
Just out of curiosity how many teams got called for fouls last year for marking discs?
DISCS are expected to undergo a reasonable amount of wear and tear as they are
handled by ROBOTS, such as scratches and occasional marks. ROBOTS that gouge,
tear off pieces, or** routinely mark DISCS will be considered in violation of G14**.
All of our test discs have the rims marked up and a lot of them are blue. We were never talked to by the ref or field crew.