Prototype Small Wheeled Shooter

[AllenGregoryIV]

We just posted a blog entry about our current prototype shooter. It uses much smaller diameter wheels than many teams that we have seen post of CD. We're hoping this idea might inspire some teams that are struggling to package their large shooters.

Blog Entry with full specs on the shooter configuration.

Youtube Video

[frcchile]

Good shooter!! what motors do you have?

[AllenGregoryIV]

Originally Posted by frcchile

Good shooter!! what motors do you have?

The blog entry has the full specs for the prototype. The two motors are a BB550 and a BAG motor.

[James1902]

Well...this is kinda awesome.

[dodar]

Originally Posted by AllenGregoryIV

We just posted a blog entry about our current prototype shooter. It uses much smaller diameter wheels than many teams that we have seen post of CD. We're hoping this idea might inspire some teams that are struggling to package their large shooters.

Blog Entry with full specs on the shooter configuration.

Youtube Video

You sir, have just lightened up alot of robots.

[Ether]

Originally Posted by AllenGregoryIV

Blog Entry with full specs on the shooter configuration.

Try slowing that second motor down (the BAG motor) . Try running it at ~10 volts.

See what happens. Easy enough to do.

[EricLeifermann]

So you're actually spinning the 2nd wheel slower than the 1st. What made you decide to do that? Seems everyone is making the 2nd wheel spin faster than the 1st.

[Ether]

Originally Posted by EricLeifermann

So you're actually spinning the 2nd wheel slower than the 1st.

Read the blog again. He is spinning the 2nd wheel FASTER than the 1st.

1st wheel 550 geared 10:1 = 1,930 free rpm

2nd wheel BAG geared 1:1 = 14,000 free rpm

[EricLeifermann]

Originally Posted by Ether

Read the blog again. He is spinning the 2nd wheel FASTER than the 1st.

1st wheel 550 geared 10:1 = 1,930 free rpm

2nd wheel BAG geared 1:1 = 14,000 free rpm

You are correct, I read the 14000 on the chart provided by FIRST as 1400.

I withdraw my question.

[ParkerF]

Allen,

This is great work! I admire your lack of hesitation to give away this information. Shows you and your team's true colors.

Thanks and good luck at making it even better!

-Parker

P.S. - Have you tried shooting from the floor? What kind of angle do you expect to have to pitch the shooter to for the 3pter?

[AllenGregoryIV]

Originally Posted by dodar

You sir, have just lightened up alot of robots.

We hope so.

Originally Posted by Ether

Try slowing that second motor down (the BAG motor) . Try running it at ~10 volts.

See what happens. Easy enough to do.

Thanks for the recommendation; we still have a lot of work to do to optimize the whole setup. With the versplanetaries we can swap around motors and gear combinations so quickly that we plan to test a large number of them. We're also going to try to standardize on voltage as well, but that will take a bit more programming (since we don't have any type of speed feedback we can't do Bang Bang yet). We'll take your advice and test it. We agree that the last wheel is spinning too fast and is most likely slipping.

Originally Posted by ParkerF

Allen,

This is great work! I admire your lack of hesitation to give away this information. Shows you and your team's true colors.

Thanks and good luck at making it even better!

-Parker

P.S. - Have you tried shooting from the floor? What kind of angle do you expect to have to pitch the shooter to for the 3pter?

Thanks for the compliments. That really depends on how high we end up shooting from and our distance away from the goal. I'm not sure we could give a number. That height was less than 5 feet so in theory we could just shoot from there.

Originally Posted by Robo Hamsters

Just wondering how you set the one gearbox to be a 1:1 ratio?

Also, anyone have any ideas as to how you mount the banebots wheels directly to a CIM?

Thanks

We took the ring gear, sun, and planets out of a 10:1 versaplanetary. I'm not sure if you can do the same with the other gearboxes. Paul Copioli can probably expand on that. If I remember I'll post pictures in tonight's blog update. We'll probably have to swap around a few of the gear ratios during testing anyway.

Originally Posted by Robo Hamsters

Also we were wondering how you direct drive the banebots wheels with a CIM.

My thought would be to get an AM 8mm Hub and drill out the Banebots wheels for that and bolt them to it. I think it would work better than the 8mm to 1/2 hex adapter (It's not very long).

Originally Posted by Tom Line

Locking a stage in a planetary gear is fairly simple - look up how people did it with globe motors. It involves glueing the sun gear and planetaries together with something, then dremeling off the teeth of the planetaries so they don't touch the ring gear.

It's much easier than that. The spline on the output shaft is the same as the one on the sun gear. You just remove the whole 10:1 stage and bolt the front and back of the gearbox together.

[Ether]

Originally Posted by AllenGregoryIV

We're also going to try to standardize on voltage as well...

If you want to do speed control, your voltage at the desired shooting speed has to be a bit less than the lowest voltage you expect to see from your battery while you're shooting -- in order to allow headroom for you control algorithm to work.

[Shu]

Did you or are you going to try the larger diameter (3.875" or 4.875") Banebot wheels?

[AllenGregoryIV]

Originally Posted by Shu

Did you or are you going to try the larger diameter (3.875" or 4.875") Banebot wheels?

We didn't and we aren't planning too. We don't have any, and we like the small form factor. We did have a 4in RC Buggy wheel you can see in previous prototype videos on the blog that worked very well but it was too big for us.

[Kevin Sevcik]

Better question is whether there's anything to be gained adding a third wheel to the setup so you can make a smother transition up to the final wheel speed. Something like starting with the BB550 in a 10:1 then BB550 in a 5:1, then the 1:1 BAG. I'm pretty sure the higher initial velocity your final wheel sees, the farther you'll shoot and faster you'll recover.