Legal ways of providing suction?
 

A number of the example robots in the game animation seemed to be possessing the ball using suction. I just mocked up a rig with a small shop-vac and a 5-gallon bucket, and it grabs and holds a ball (with cover) very well. Now I'm wondering: how can I legally provide that suction?

Rule R29 lists the allowed motors, and includes the following category: "Drive motors or fans that are part of a motor controller or COTS". In the glossary, COTS has very few limitations beyond "off-the-shelf", so could I buy and use a small 12VDC vacuum cleaner, driven by a Jaguar? (I'm dubious, because if this is covered by COTS then it seems like an enormous loophole for powered devices.)


Thanks,
Dan

Re: Legal ways of providing suction?
 

In the past, we made a custom duct around the turbine thing (I'm bad at explaining, I had very little to do with it's construction). It was powered with a legal motor (IIRC, it was a banebots).

Re: Legal ways of providing suction?
 

Take your vacuum apart, remove the motor from the suction device, and replace it with a legal motor as close as possible to the suction motor.

You could also use a venturi device off the pneumatics system, but that's not going to work nearly as well.


Where you went astray was cutting off the rest of that line about COTS. The full line reads, "Drive motors or fans that are part of a motor controller or COTS computing device", which a vacuum is NOT.

Re: Legal ways of providing suction?
 

You could also use an airbed inflator, in reverse, using a curved shield with a good rubber seal.

Re: Legal ways of providing suction?
 

You can always disassemble the cots vacuum and remove the factory motor, replacing it with a first legal motor. Then it should be 100% ok. Might be a lot of work though.

Eric Ninjad me, darn. serves me right for not clicking submit reply

Re: Legal ways of providing suction?
 

Spend some time on repair sites looking at different shop vacs. Some 12 Volt (rechargeable) ones use 550 motors - we experimented with these in 2010 for holding the soccer balls.

Re: Legal ways of providing suction?
 

Oh, my goodness, is that confusing. In the decrypted PDF, the table in rule 29 ends at the bottom of page 17 with "Motor Name" given as "Drive motors or fans that are part of a motor controller or COTS", and "Max Qty Allowed" given as "Unlimited".

Then, at the top of page 18, "Motor Name" is given as "computing device", and "Max Qty Allowed" is given as "". Nasty, nasty, nasty. (And good catch, EricH. Thanks.)

Re: Legal ways of providing suction?
 

I'm using the PDF off the Manual site--clicking "Save As PDF"--and it's a LOT cleaner. I recommend you give it a try.

Re: Legal ways of providing suction?
 

Following this thread. Could be interesting.

Re: Legal ways of providing suction?
 

Hmm... if only teams had a 3D printer they could make their own impeller design.

What's that? You've got a 3D printer you say?

http://www.thingiverse.com/thing:29623/#instructions

http://www.thingiverse.com/thing:7273

http://www.thingiverse.com/thing:13188

Might help get you started.

Jason

Re: Legal ways of providing suction?
 

Excellent idea: thanks.

Re: Legal ways of providing suction?
 

Reading this reminds me of a seine in StarWars Phantom Menace during the pod race and the little robot got sucked in the turbine. :D

Re: Legal ways of providing suction?
 

I think it's time for some machining :D. You could build a compressor-based suction-cup. However, that would generate a lot of suction, so you should really have a manual release valve.

How it works:

So you have a reciprocating piston, with an intake (suction) and an outtake (the atmosphere)


^=Output v=Suction intake
---^---v---
| Piston |
|====== |
| | |
| |----------------Pushrod
| | |
| |||\ |
| ||| \ |
| ===\ |
/ \
Motor Crankshaft




Hopefully you guys liked my ASCII Art :D
I don't know if CD likes ASCII art :(

Re: Legal ways of providing suction?
 

Won't work for any extended amount of time, because air leaks past the ball covering. You'd need continuous suction to maintain your hold for more than a couple of seconds.

Try the [code] tag; it will render using monospace fonts, e.g.

Re: Legal ways of providing suction?
 

I'll try the code tag.

Also, the idea of the compressor is that it will continuously run when you want the ball to be held!

Re: Legal ways of providing suction?
 

Could said shop-vac be disassembled and modified to use a CIM/Banebots/other legal motor?

In 2010 we went to Goodwill and bought a vacuum cleaner that we tore apart and used. The trick is interfacing an FRC legal motor. The best setup we could muster was a 1:1 direct drive setup running off very small timing belts. Those vacuum impellers need to spin at like 15k rpm to function properly.

I like the idea above about finding a vacuum that runs off a 500 series motor. That could make mounting an RS-550 or AndyMark 9015 somewhat trivial.

Re: Legal ways of providing suction?
 

It seems as though a compressor sucker may be the easiest because they will get high pressures and are easier to build. You have more leeway when working with these! Also, you don't need the 15k RPM which only those tiny motors can offer!

Re: Legal ways of providing suction?
 

Can you speak from experience? In MY experience, spanning years including 2004, 2008, AND 2007 (when suction cups were included in the KOP), the compressor-based systems didn't do very well. 2008 was particularly bad, given the cloth cover of the ball--which, I might add, is a larger version of this year's ball. In 2007, very few teams could get the KOP suction cups (Venturi devices) to work right--on inner tubes that were just about made for grabbing by suction. In 2004, if you couldn't get a good seal, you were not picking up the ball. OTOH, I saw at least one good suction cup that was a converted vacuum in 2004, and heard about another in 2008.


Different vacuums and impellers need different speeds. Maybe you don't need a 15K RPM impeller. Maybe a 4K one will do--but the impeller won't be the same as for the 15K one, I'll bet you that.

Re: Legal ways of providing suction?
 

You don't need high pressures. Using a 5 gallon paint bucket for a grabber, that's a 12" diameter circle, or about 110 square inches (sorry, I'm an Imperial thinker). Say you want a 30 pound force to hold the ball in place: that's about 1/4PSI, or about a 6" head of water.

What you need is a significant flow of air to pull the ball into place and establish the seal. Without that, you'll have to trap the ball against a surface before you'll be able to pick it up.

Re: Legal ways of providing suction?
 

any brand name suggestions for the 550-bearing models? Found coleman and itek pumps in 12v models. Maybe a $20 sacrifice will be worth it. :yikes:

Re: Legal ways of providing suction?
 

In 2010, we used a Black and Decker "Dustbuster" with good success.

You don't actually need for the donor vacuum to be 12V, as long as it has a 550 motor inside, as you'll be replacing the motor anyway. You'll need to take out the original motor and replace it with a 2014-legal motor. The BaneBots RS-540 / RS-550 or AndyMark 9015 motor (am-0912) would all be good choices.

The trick is that it will be very hard to guess what has a 550 motor without actually disassembling the vacuum. Buy a few until you find one that works. If nothing else, you'll have a clean build area! :-)

In any case, we disassembled the B&D "Dustbuster", keeping only the impeller and chamber around the impeller, and throwing everything else away.

It worked great for holding soccer balls in 2010. Initially, we used just a single stage with one motor/impeller. We later added a second stage with another motor/impeller.

We even tried out our 2010 vacuum on a 2008 trackball. (See photo.)

If it's not obvious from the photo, it worked!

Re: Legal ways of providing suction?
 

In 2008, the Red Barons used the suction unit from a whole house vacuum system. We powered it with a large CIM. And a large potato chip bowl was the suction cup. The suction aspect worked pretty well, but it was slow to acquire a ball.

Re: Legal ways of providing suction?
 

We used a 120 VAC "bucket vac", designed to fit atop a 5 gallon bucket, bought from Lowe's for $23. The motor was removed and replaced by a CIM, to excellent effect.

So long at you use an FRC-legal motor, you should be OK.