Ball Launchers? Ideas?

[sometimestommy]

Hey there. Today we discussed various launchers.
Spring Loaded
Throwing Arm
Pnuematics?

Any ideas? Pro/Cons?

Thanks!
Thomas 1939

[the man]

I want to see the animation robot with the plunger to pick up balls and the boots that spin to kick them. Could you do that please. It would be very awesome.

[Anupam Goli]

I'm actually thinking of a conveyor belt going from an intake roller all the way up to 2 wheels that spin like pitching machine wheels to launch the ball. 45 degree angle for maximum distance, adjustable speed on the wheels for height.

[Starke]

Originally Posted by the man

I want to see the animation robot with the plunger to pick up balls and the boots that spin to kick them. Could you do that please. It would be very awesome.

Check out 1771 on FRC Designs Gripper page (See Link Below). This arm used a suction system to grab the ball and then used a device to launch the ball.

http://frc-designs.com/html/grippers.html

Matt

[Grim Tuesday]

Originally Posted by Starke

Check out 1771 on FRC Designs Gripper page (See Link Below). This arm used a suction system to grab the ball and then used a device to launch the ball.

http://frc-designs.com/html/grippers.html

Matt

I wish FRC Designs had some stuff from '06...

[seg9585]

As a 2006 FRC participant (Aim High) who built a robot using the pitching machine launcher design, I have a few comments about it:

First off, calibrating the wheels ended up being a little more annoying than expected. Even though we used encoders to measure and even out the speed between each wheel, we found the release angle was still inconsistent -- the balls needed to be squeezed by the wheels a bit to get the traction needed to accelerate the ball, and the balls would end up flinging a bit to the right or left depending on which wheel made contact with the ball first and how the ball re-expanded.
For Aim High this wasn't a big deal because the target was relatively large, but with baskets this year we need a lot more precision.

Also, the ball originally came out without spin, so the balls flew like a knuckleball, making scoring unpredictable. We changed the speed of one wheel to add spin, but then had to apply a directional bias since the spin did induce lift on one side of the ball (still better than a knuckleball)!

Lastly, we had to run those large softball wheels with CIM motors to get them spinning fast enough, but when they were on all match it quickly drained our battery. In later matches we had to turn off the spinner during collection periods just to save power, then wait for the wheels to spin up to speed again.

I did see effective single-wheel launchers against a static surface that took out a lot of the multi-wheel variable issues we had, and they seemed to work well.

[PayneTrain]

Originally Posted by seg9585

As a 2006 FRC participant (Aim High) who built a robot using the pitching machine launcher design, I have a few comments about it:

First off, calibrating the wheels ended up being a little more annoying than expected. Even though we used encoders to measure and even out the speed between each wheel, we found the release angle was still inconsistent -- the balls needed to be squeezed by the wheels a bit to get the traction needed to accelerate the ball, and the balls would end up flinging a bit to the right or left depending on which wheel made contact with the ball first and how the ball re-expanded.
For Aim High this wasn't a big deal because the target was relatively large, but with baskets this year we need a lot more precision.

Also, the ball originally came out without spin, so the balls flew like a knuckleball, making scoring unpredictable. We changed the speed of one wheel to add spin, but then had to apply a directional bias since the spin did induce lift on one side of the ball (still better than a knuckleball)!

Lastly, we had to run those large softball wheels with CIM motors to get them spinning fast enough, but when they were on all match it quickly drained our battery. In later matches we had to turn off the spinner during collection periods just to save power, then wait for the wheels to spin up to speed again.

I did see effective single-wheel launchers against a static surface that took out a lot of the multi-wheel variable issues we had, and they seemed to work well.

Maybe I'm just a little slow in the head after the flow of information today, but why didn't you set up the robot so you could have identical gears underneath the wheels that would allow them to turn at the same rate?

[the man]

I think our ball launcher should have the wheels spinning around 80mph. But that's a rough estimate we'll see what actually happens.

[Sean Raia]

Can you clarify that? Rotational speed typically isnt measured in mph.

[Marc S.]

Originally Posted by the man

I think our ball launcher should have the wheels spinning around 80mph. But that's a rough estimate we'll see what actually happens.

What is 80 mph converted to rpm? Or are you planing on shooting your wheels at a speed of 80mph.

[the man]

Well I estimated what the cim speed would be because I have no idea. I converted it in to mph to make it more easily recognized. But Yeah I have absolutely no idea how fast a cim would actually be spinning but. I took the diameter of the wheel in ft, .5, multiplied it by pi. multiplied it by rpm which I just put in 4500 because I have no idea. Oh yeah the Cim motor would be directly connected to the shaft through the wheels. Then I divided by 60 to give me ft per second. and converted it to mph.

Does any one have any rough ideas as to how fast a cim motor would be spinning under a load of a 6in wheel that is free spinning?

[davidthefat]

This looks cool: http://www.chiefdelphi.com/media/photos/33185

[Mark Sheridan]

Originally Posted by davidthefat

This looks cool: http://www.chiefdelphi.com/media/photos/33185

If a team is going to store rotation energy to launch the ball, this is the way to go. Many teams have had some success with this style including me when I was on 766. It generates a lot of backspin, which improves accuracy and creates a shallower bounce of a backboard.

I am really curious what is the limit of accuracy for this design. Shooting a basket is much harder than 2006's game. Hopefully next weekend we will get a prototype running to see if this is practical.

[Trez]

Originally Posted by seg9585

As a 2006 FRC participant (Aim High) who built a robot using the pitching machine launcher design, I have a few comments about it:

First off, calibrating the wheels ended up being a little more annoying than expected. Even though we used encoders to measure and even out the speed between each wheel, we found the release angle was still inconsistent -- the balls needed to be squeezed by the wheels a bit to get the traction needed to accelerate the ball, and the balls would end up flinging a bit to the right or left depending on which wheel made contact with the ball first and how the ball re-expanded.
For Aim High this wasn't a big deal because the target was relatively large, but with baskets this year we need a lot more precision.

Also, the ball originally came out without spin, so the balls flew like a knuckleball, making scoring unpredictable. We changed the speed of one wheel to add spin, but then had to apply a directional bias since the spin did induce lift on one side of the ball (still better than a knuckleball)!

Lastly, we had to run those large softball wheels with CIM motors to get them spinning fast enough, but when they were on all match it quickly drained our battery. In later matches we had to turn off the spinner during collection periods just to save power, then wait for the wheels to spin up to speed again.

I did see effective single-wheel launchers against a static surface that took out a lot of the multi-wheel variable issues we had, and they seemed to work well.

Why didn't your team just use one motor with some gears to run both wheels?

[slijin]

Originally Posted by Trez

Why didn't your team just use one motor with some gears to run both wheels?

Discrepancies in wheel inflation/material necessitated that they offset the speed of one, and consequently introduced a need to change the final shooter direction - at least, that's how I'm reading it. No matter how well you gear it - to say nothing of the difficulty of such a setup - there's going to be enough leeway in the wheels themselves, let alone the leeway given by the gears and sprockets to introduce significant error into the equation.