Off season T-Shirt Launching Tank Robot
 

As an off season robot, 3647 is making a Tank bot that shoots T-Shirts!

So far we've caded up the entire base and the turret is still being worked on

https://imgur.com/pwvzBGG

Side view: https://imgur.com/2hWbAKr

Yes, that is TWO batteries you are seeing, we've made a parallel battery connector to power the whole thing

Turret

https://imgur.com/WhsL0UQ

Each shell falls down and after the t-shirt is shot, there is a small piston on the side to shoot it out of the ejection cover.

Shooting test with only a air tank, valve, and barrel

https://youtu.be/LVJDTHKDO3s

Shooting Specs:

110 psi (though we will probably shoot at a lower psi)

1inch sprinkler valve

1 gallon tank (When shooting at 80 psi it drops to about 60)

For air storage there is a huge 5( I think) gallon tank

Some actual build pictures:

VHB Tape is apparently really, really strong!
http://imgur.com/Bp3wYWq

Wiring looking nice
http://imgur.com/p9hF0ec

Storage tank mounted
http://imgur.com/xmi4PFv

PWM Cables routed
http://imgur.com/5MvsXxP
http://imgur.com/bq1Qzzo

Big thanks to hectorcastillo for the retention clip CAD (https://grabcad.com/library/roborio-...tention-clip-1)

General overview
http://imgur.com/FqQkIrm

Specs:

6 CIM West coast drive for Treads ( no tank drive as the drivetrain is just too long to be powered like that)
10 Victor 888s
Roborio controller
Frame size: 23w x 35l

still have a ways to go!

Re: Off season T-Shirt Launching Tank Robot
 

Looks like a lot of great work has already gone into it! Have you looked at the possibility of using a scuba tank to supply air? They are a lot higher pressure, but the standard first stage scuba regulator (the part that attaches to the tanks) brings it down to around 100psi which you can use a standard regulator to handle. The only think that was tricky on ours was an adapter to go from the scuba fitting to 1/4 npt I believe. It was nice to have the pressurized volume to shoot hundreds- if not thousands of shirts before worrying about running out of air. Overkill-- maybe, not having to worry about compressors-- priceless.

We also are using a vex cortex and controller to control the robot. It takes less time to boot and connect, and conserves roborio's for competition or practice bots. We continued to use the blue pdp like yours though.

Re: Off season T-Shirt Launching Tank Robot
 

That looks expensive, but I'm sure it will be AWESOME when it's done! I look forward to seeing more pics of this!

Re: Off season T-Shirt Launching Tank Robot
 

Cue argument over PVC barrel

Re: Off season T-Shirt Launching Tank Robot
 

Translation: It'll be pressurized-air-rated material X barrel before long. Or else encased in a Lexan box. I might suggest ABS if it's got the proper ratings.

Just one of those things that need to be thought about early rather than late. OTOH, barrels aren't all that hard to swap out if needed...

Re: Off season T-Shirt Launching Tank Robot
 

We thought about it but it is fairly expensive. We also have a very fast air compressor that will fill the entire thing in about 1ish minutes.

We already have the stuff do we don't really want to buy anything more, and if we need the roborio we'll just take it off.



I've read quite a bit about this, and we've decided to use the regular pneumatic tubing from the storage tank to the shooting tank, metal pipe from the storage tank to the valve, and for the barrel we'll either use some stiffer drain pipe stuff (which is fairly soft and appears to be made of polycarbonate sheet) or metal.

though cue my signature "this is safe... right?"

Re: Off season T-Shirt Launching Tank Robot
 

Air is MUCH more compressible than water. This means that compressing a volume of air to 120 PSI takes several thousand times more work than compressing the same volume of water to the same pressure. As a consequence, there is MUCH MUCH MUCH more energy to be released.

In general, only use devices rated for air pressure (not water pressure) to handle air. In particular: DO NOT USE A "SPRINKLER VALVE" to control air pressure. While the pressure/force is no greater, the stored energy in air is three or four orders of magnitude higher than that stored in water at the same pressure. Do not use PVC or other random plastic containers to store air.

For a T-shirt launching air cannon, I recommend at least a 3/4" (and preferably a 1") AIR-rated solenoid, and that all hoses be of similar diameter. With a 3/4" solenoid valve, 3/4" tubing, and 60 PSI pressure, we have thrown t-shirts and foam footballs over our press box onto 9th street; it is unlikely that you will need greater pressure to get t-shirts into the top levels of your stands.

Re: Off season T-Shirt Launching Tank Robot
 

Have you thought about what the scrub from the tank treads are going to do to your football field?

Looks like a cool project with a lot of thought

Re: Off season T-Shirt Launching Tank Robot
 

I REALLY want to see how your auto loader design works! is it sealed on the edges in any way?

I was playing around with a quick load breach design for a "Man Portable" multi shot cannon, and this might be the solution to pull it off smoothly!

Re: Off season T-Shirt Launching Tank Robot
 

Really good string here. We built a t-shirt cannon a few years ago and only used it once.

Team pays about $18 for our t-shirts (yes, seems high to me too) and we'd shoot them to kids at a football game that didn't even want them.

Turned out to be a fun project, but not such a good idea.

Gotta figure out a way to shoot t-shirts that someone else pays for.

Re: Off season T-Shirt Launching Tank Robot
 

We recently finished our own shirt cannon bot, and (like other posters have said) I'd recommend trying to get your hands on a SCUBA tank. We asked a local dive shop if they were willing to donate on (it's a good cause) and they gave us an old one AND a first-stage regulator, too. The capacity is enormous; I'd estimate about 80-100 shots at our usual 70 psi. The only hassle is getting it refilled, but we know in advance when it needs to make an appearance and can plan accordingly.

In addition, you're definitely going to want to grab an air-rated valve. We found a good one for <$25 on amazon (even has free shipping) that is rated for well beyond any pressure you're going to shooting with, and is also very quick to open and close.

Looking pretty great so far though, the turret mechanism and tracks are going to be a hit when you unveil it.

Re: Off season T-Shirt Launching Tank Robot
 

You can buy shirts for <$5.00 in qty. Maybe not what you want for your team shirts, but for giveaways, they work. Buying overstocks, seconds, and having your school's graphics art department print them is a possibility as well. Talk to the football booster club. They can get shirts from their sponsors. Sponsors like for there shirts to be shot into the crowd.

Re: Off season T-Shirt Launching Tank Robot
 

Actually a great idea, shooting sponsor shirts.

Another ironic problem we had was we didn't really have any robotics kids that wanted to go to the football games.

But it does give your team more visibility in the school and might help some of the sports-people tolerate you.

Might dust off the old robot and try that....

Re: Off season T-Shirt Launching Tank Robot
 

This concept reminds me a lot of this one I posted a few months back. I hope when it's finished you'll post a video of the feed system running.

On the note of scrub that was brought up earlier, if you offset the centermost rollers of the tank drive the resulting wedge functions much like a typical dropped center 6wd.

Re: Off season T-Shirt Launching Tank Robot
 

We have a few pep rallies during the year (which includes throwing t-shirts into the crowd) and also many sports events which we can probably get the school to give us t-shirts.

Our football field is turf instead of grass so it won't rip stuff up. We would also probably prefer to do these things in the gym instead.

Thanks for the reminder! I'll be sure to remember to put a center drop. Luckily we still have not made the two side panels!



We still have quite a bit of stuff to buy like the metal side panels (which also need to be sent off to be cut!) , some more tank pulleys so the chassis might be a bit of time but we'll probably start on the turret very soon!

Re: Off season T-Shirt Launching Tank Robot
 

Small update

https://i.imgur.com/SX6I1hK.jpg

Side panels came in and we mounted them on the robot. The ones pictured are only the inside ones, there are also a pair of outside ones for more strength.

Turret is mostly done but there is still a lot to do with the shooting and loading mechanism.

Also notice he parallel battery connector :ahh:

Night pic with it all together

https://i.imgur.com/SNBZ4A0.jpg


Closeup of turret angle mechanism

https://i.imgur.com/zBtOJYK.jpg

Earlier stage of turret

https://i.imgur.com/iWklG63.jpg

Partially finished turret on robot

https://i.imgur.com/lDK5GSd.jpg

Should be about another week or so until it is all finished!

Re: Off season T-Shirt Launching Tank Robot
 

Looking good! Are there any plans to paint it once it's done?

Re: Off season T-Shirt Launching Tank Robot
 

We originally wanted to paint it but taking it all apart is too much work especially since a lot of wires are zip tied to the boards.

Re: Off season T-Shirt Launching Tank Robot
 

Almost done!

Here's a short video of our shooting test on the robot. Still have to get some code on the robot to run it. The turret is also on backwards but we're too lazy to run some code to turn it around haha.

https://www.youtube.com/watch?v=vC1d51Z6fuY

Now we just have to finish the pneumatics, loading mechanism, 3D print a ton of wheels, and finish the drive train.

Some more pictures: https://imgur.com/a/iF3vY

Re: Off season T-Shirt Launching Tank Robot
 

Two questions:

1. What type of storage tank are you using for your accumulator, what pressure does it operate at, and where did you get it from?
2. What type of hose are you using between the accumulator and the cannon?

It's looking great so far, can't wait to see the finished product! :)

Re: Off season T-Shirt Launching Tank Robot
 

looking great!
what is the max firing rate?

Re: Off season T-Shirt Launching Tank Robot
 

1. The shooting tank is a metal storage tank that operates at anywhere from about 70 psi if we're low on air to 110 when we're full on air. It is rated of 220 psi I think. The big black tank is just another metal tank that holds 120 psi and slowly feeds into the shooting tank. Not actually sure where we got either from sorry!

2. 3/4 inch pvc hose. It is rated for up to 120 I'm pretty sure.

Right now the magazine isn't done so we don't really know the firing rate, but it should be fairly fast as after it shoots it just unlocks the shell, ejects the shell, then lets the next shell fall down and finally seals the shell and it is ready to shoot.

Re: Off season T-Shirt Launching Tank Robot
 

As an Ex-3647 student... i remember that tank...

The smaller grey tank was obtained from McMaster-Carr and is stupidly heavy/overbuilt for FRC competition uses (like 300+ PSI).

The bigger black one looks like it's an off-road compressor tank used by off-roaders for air reserves. IE http://www.walmart.com/ip/42279947?w...590128&veh=sem

We have used the later on 2485 to good success.

Re: Off season T-Shirt Launching Tank Robot
 

The smaller tank was the one I was interested in because of the large output port, almost every other tank I've found has much smaller (1/8" typically) ports which makes adapting to a 1" sprinkler valve (or non-plastic functional equivalent) much harder.

EDIT: Is this similar to what you have? http://www.mcmaster.com/#9908K19