Vacuum Pickup

[Ty Tremblay]

I helped design 190's 2008 suction cup. A neat thing we learned is that current goes down significantly when the ball is captured. This is because there is less air getting in the way of the impeller blades.

Additionally, we learned that rate of removal is more important than the actual vacuum you draw. Those fabric covers are mighty porous.

[nuggetsyl]

You can use a model airplane prop to pull a ball in. Then just turn it off and kick the ball.

[Nathan Streeter]

In 2010 we also used a vacuum to hold the soccer ball. It had an excellent grip on the soccer ball (combination of suction force, area applied on ball, and "mechanical advantage" of how wide your grip on the ball is).

We used a two-stage system to pull a stronger vacuum, both stages were identical, using an impeller and impeller housing from a hand-held mini-vac with the stock motor replaced by a Fisher Price. That year we used a large, soft toilet plunger as the suction cup... I'd recommend something comparable in size to the bucket used in this video though.

Some design recommendations:
- Make sure your method of getting the cup to the ball is effective... even if the vacuum works perfectly, it will help you little if your drivers are always fumbling to acquire the ball. Iterate this, and don't underestimate it.

- Use a "suction cup" with a large diameter, but minimize the volume inside it so the vacuums don't have to evacuate as much air to get a good grip

- Find some cheap vacuums (shop vac or hand-held, probably) which you can salvage the impeller and impeller housing from. Carefully disassemble them and press your own motor on (RS550 would be my recommendation, given the high free speed, stall-less application, and excellent power-to-weight ratio).

A vacuum should be pretty low-power... Ours used two Fisher Price motors, but each drew only a few amps if I recall correctly. Don't worry much about the current draw... it won't require hundreds of watts.

[Kevin Thorp]

Thanks for all the great tips. We've found large diameter (=>10") vacuum cups online, but they seem to be for flat surfaces.

We have access to a 3D printer. In past years we've made molds with it & cast urethane wheel treads. I suppose we could do the same for a big vacuum cup.

[BotDesigner]

What does anyone think about using a vacuum for a pick-up this year in Stronghold? My team was discussing it it yesterday, so I am wondering how (or if) we should go about developing a vacuum pick-up for a low goal bot.

[Taylor]

Originally Posted by BotDesigner

What does anyone think about using a vacuum for a pick-up this year in Stronghold? My team was discussing it it yesterday, so I am wondering how (or if) we should go about developing a vacuum pick-up for a low goal bot.

For large game objects on a high visibility field, vacuums could be fine.
For smaller objects on a very limited visibility field, vacuums would require quite a bit of precision.

[inorbert]

My team tested it with low results

[Kevin Thorp]

We had good results in 2014 (https://youtu.be/tPNvIXTAd4s), but decided not to use vacuum because adapting a FIRST-legal motor to a small shop vac was beyond our resources at the time. But another team won our regional with a vacuum pickup. That was Aerial Assist & the game piece was a giant yoga ball with a fabric covering.

I recommend high flow/low vacuum like a small shop vac produces, rather than low flow/high vacuum, as you would get from a venturi-type vacuum generator. Those things are small and light but require a LOT of pressurized air to work.

To prototype just cut a hole in the bottom of a plastic pail or bowl & duct-tape a vacuum hose to it. Even a cheap vacuum can generate ~60" of H20 vacuum (about 2psi). With a 6" diameter bowl: 2 psi x 3 x 3 x pi = 56 lbs lifting force! Even at 50% loss due to leakage, etc. that's still 28 lbs. You might need to vent your system to keep from collapsing the boulder.

Happy prototyping!

[Ryan Dognaux]

We've included a vacuum in our puncher prototype mechanism. So far using a shop vac we've found that the boulder lends itself well to vacuum suction for maintaining control. Also if you get the vacuum over the pinhole, it sucks all of the air out of it and makes your boulder look like a brain or a raisin. https://youtu.be/f24bk-4sZCo?t=54s So that's fun.

[BoilerMentor]

Vaccuum repair shops are quick to give you their broken motor assemblies if you ask.

I'd agree with Taylor's assessment about the relative size of the game pieces and visibility.

It worked pretty well in 08 for 1741.

http://www.thebluealliance.com/match/2008in_qf2m1