View Full Version : Pneumatic Ball Puncher
Dr.Gusta
09-01-2014, 13:15
Okay so I am apart of a rookie team this year, we are team 5107 The Neurotoxoins. We have the idea of using a pneumatic piston to literally punch the ball and propel it. The only issue is none of us have worked with pneumatic before. What we were wondering is if the piston would extend fast enough and with enough force to propel the ball. Thoughts? Ideas?
Thank you,
Brenden Geary
Ty Tremblay
09-01-2014, 13:26
The problem most teams are running into (you can find their posts with a quick search) is that the solenoids used to control the pneumatic cylinders do not allow the air to flow through them fast enough. You'll get the cylinder to move, but it won't be the punching action you're thinking of.
You could try using the cylinder to move a lever to increase the speed of the ball.
Personally, i would recommend using surgical tubing to power your shooter. You got some in your kit and it's easy to find online.
No.
Well, its not quite that simple.
Generally speaking, no, a pneumatic piston that is otherwise FIRST-legal will not be able to impart enough energy to the ball quickly enough to "punch" it to a sufficient height to clear the TRUSS or the HIGH GOAL.
There ARE ways you can build a pneumatically powered firing mechanism that WILL do the job. Prototype your ideas and see what works and what doesn't.
First of all welcome to FIRST and Chief Delphi!
There are many thread on this subject started already. I would suggest that you do a search and join in on those conversations.
Good luck.
Agreed, from our testing, punching, using surgical tubing , say like 8 seperate rubber bands, should do the trick, especially at a 45 degree launching angle, from a predetermined sweet spot.
Brandon Zalinsky
09-01-2014, 13:43
No.
I guarantee at least one robot on Einstein will use a pneumatic punch, either one large cylinder or 3-4 smaller ones.
Look at the Simbotics robot from 2008. It uses what appears to be one cylinder to propel a much larger and heavier ball over the overpass.
Ty Tremblay
09-01-2014, 13:50
Look at the Simbotics robot from 2008. It uses what appears to be one cylinder to propel a much larger and heavier ball over the overpass.
They used surgical tubing and a winch to shoot in 2008. (simbotics.org/files/pdf/Simbotics_GM_Display.pdf)
JohnSchneider
09-01-2014, 13:57
I guarantee at least one robot on Einstein will use a pneumatic punch, either one large cylinder or 3-4 smaller ones.
Guarantee is a really strong word... On what basis can you be 100% certain of the types of robots that will be on Einstein?
themccannman
09-01-2014, 14:17
I guarantee at least one robot on Einstein will use a pneumatic punch, either one large cylinder or 3-4 smaller ones.
I seriously doubt that. Maybe pneumatics attached to a lever arm to throw the ball, but absolutely not to punch it.
Dr.Gusta
09-01-2014, 14:41
After looking at symbotics I really like their winch idea and would incorporate very well into the design and Claw we have at the moment. Are we allowed to "steal" their wench design from 2008.
AdamHeard
09-01-2014, 14:42
After looking at symbotics I really like their winch idea and would incorporate very well into the design and Claw we have at the moment. Are we allowed to "steal" their wench design from 2008.
I wouldn't recommend stealing their wench, but I'm sure they wouldn't mind others using that winch design.
lgphoneeric
09-01-2014, 14:56
After looking at symbotics I really like their winch idea and would incorporate very well into the design and Claw we have at the moment. Are we allowed to "steal" their wench design from 2008.
Yes, you can borrow their design. You can steal from the best and invent the rest. Look at any game and look at how many robots are based off the same design, you would be very surprised.
theCADguy
09-01-2014, 14:59
Team 20 has prototyped pneumatic system to propel the ball. We had absolutely no luck. The system barely got the ball in the air. :(
thinker&planner
09-01-2014, 15:05
I guarantee at least one robot on Einstein will use a pneumatic punch, either one large cylinder or 3-4 smaller ones.
I can almost guarantee that there will not be a successful robot that uses one giant piston for this reason: You are extremely limited to the amount of air that you can get into a giant piston by tubing and fitting size, not even accounting for valve size.
That being said, I believe that it will be possible to use multiple smaller pistons to launch the ball at a decent rate.
Ed Sparks
09-01-2014, 15:12
Look at the pneumatic rules very closely. There are deliberate specs in these rules to slow down the transfer of energy from the holding tank to the actuators (small valves, small id tubing, 60 PSI working pressure). At some point, given the mass of whatever were tossing, the physics just doesn't work out. If we were allowed to use 1" actuated ball valves and 1" tubing ...... well ...... we could be having some chunk'n fun.
Keep in mind, that using a punch, similar to Team 1114 from 2008, also allows you to shoot straight ( towards an alliance partner for an assist ) &
tilting forward ( to harvest a ball from the field ). Plus, if designed with some reinforcement, could make somewhat of a mitt, for catching.
Keep in mind, that using a punch, similar to Team 1114 from 2008, also allows you to shoot straight ( towards an alliance partner for an assist ) &
tilting forward ( to harvest a ball from the field ). Plus, if designed with some reinforcement, could make somewhat of a mitt, for catching.
This was exactly my teams idea before we prototyped. In theory, yes it would be the perfect design. After actually prototyping it, we found that the air flow through the required tubing was not high enough to actually move the ball more than a few inches off the stand. We did try many different cylinders with similar results.
Not sure what cylinders you used but we tested with 2 3/4 inch cylinders of about 8 inches of throw hooked up back to back and triggered with 2 separate valves and got about 4 ft of throw.
Gonna try 3 pairs of 9/16 cylinders tonight.
Zealii, sorry, I wasn't implying pneumatic cylinders, I was implying using stretched surgical tubing to provide the punching force.
Kevin Sevcik
09-01-2014, 17:00
Not sure what cylinders you used but we tested with 2 3/4 inch cylinders of about 8 inches of throw hooked up back to back and triggered with 2 separate valves and got about 4 ft of throw.
Gonna try 3 pairs of 9/16 cylinders tonight.What were you using for valve, tubing, etc.? Are you certain this was an FRC legal setup?
Brandon Zalinsky
09-01-2014, 19:27
I seriously doubt that. Maybe pneumatics attached to a lever arm to throw the ball, but absolutely not to punch it.
Mark my words.
One cylinder got our team an undefeated qualifications in 2008. I'm loving your "absolutely not" certainty- our punch prototype shoots 25 feet. I repeat my guarantee- at least one team on Einstein will have a linear pneumatic punch shooter.
bbradf44
09-01-2014, 19:54
Mark my words.
One cylinder got our team an undefeated qualifications in 2008. I'm loving your "absolutely not" certainty- our punch prototype shoots 25 feet. I repeat my guarantee- at least one team on Einstein will have a linear pneumatic punch shooter.
Can I ask what your setup is? Like what kind of piston and flow rate? Despite warnings from others on here my team is planning on a punch shooter but we don't have enough materials to build a full working prototype then another one for the robot
our punch prototype shoots 25 feet
Are you using the cylinder end cap as the hard stop?
martin417
09-01-2014, 20:28
I was about to get up on my soapbox, but the topic seemed so familiar that I looked at some of my old posts and found this one from 2008. (http://www.chiefdelphi.com/forums/showthread.php?t=66496&highlight=impossible)
The post atarts with this quote:
"When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong."--Arthur C. Clarke
When you act as an expert and tell people that that "it wont wok", you are not inspiring them, you are preventing them from exploring and learning.
By the way, after that post was made, the team was invited to attend championships, played in the quarterfinals there, and won the Xerox creativity award.
Please read the post and think before you stifle creativity.
PANTHERPROJECT
09-01-2014, 20:30
Team 2064 made prototypes for a pneumatic catapult instead of the ball puncher because we had absolutely no luck with the puncher, however the catapult is making progress. We're trying out different solenoids to see which one works best and I suggest that you do the same.
We have tested with four 3/4" X 10" stroke cylinders with a festo solenoid valve per cylinder and an accumulator feeding each valve at 60psi and have been able to get about 7 feet straight up from the ball resting on top of the cylinders that are spaced evenly around a 4" diameter tube. We were getting 4' with three. We plan to use 6 and hold with vacuum next test. Will let you know how it works... Not a punch -- more of a put (like shot put).
Brandon Zalinsky
09-01-2014, 22:06
Can I ask what your setup is? Like what kind of piston and flow rate?
We're using multiple 3/4", 12" stroke cylinders which each have their own solenoid and dedicated accumulator on the 60psi side.
Are you using the cylinder end cap as the hard stop?
[I]
Yes
Are you using the cylinder end cap as the hard stop?
Yes
May I ask, what is the part number of the cylinder?
themccannman
10-01-2014, 01:17
Mark my words.
One cylinder got our team an undefeated qualifications in 2008. I'm loving your "absolutely not" certainty- our punch prototype shoots 25 feet. I repeat my guarantee- at least one team on Einstein will have a linear pneumatic punch shooter.
The only way you could get a decent shot is if you manually stopped the piston from extending, and allowed the pressure to evacuate form the decompressing side before releasing it. I'm not even sure if that's legal though.
Wren Hensgen
10-01-2014, 05:57
With regards to allowing the pressure to evacuate, why bother? Just leave the top of the cylinder disconnected, and allow the weight of the rod to return it to rest when the solenoid is fired.
arizonafoxx
10-01-2014, 09:06
I think some people might want to look at some of the soccer kickers from 2010. Many of the kickers that year were surgical tubing assisted by pneumatics. Kicker was drawn back and latched with pneumatics which stretched the surgical tubing. Then the solenoids were actuated in the other direction and then the latch was released. It was discovered that lots of energy was stored and released this way. So I tend to agree that there is a possibility that a punch using pneumatics could end up on Einstein.
Kevin Sevcik
10-01-2014, 09:18
The only way you could get a decent shot is if you manually stopped the piston from extending, and allowed the pressure to evacuate form the decompressing side before releasing it. I'm not even sure if that's legal though.It was legal in 2010 and a fairly popular method of powering kickers.
jacqlecl772
10-01-2014, 09:42
well my team original idea was to use pneumatic but we simply could not get the piston to extend fast enough to push the ball far enough. We even called are pneumatic guy to ask him if he had any cylinders that could open with such speed and force but he told us that he could not think of any way to do it. So i would say that to my knowledge there is no way of using pneumatic to shoot the ball in to the high goal, however it may be possible in the low goal.
Your best bet is to prototype some different shooters and pick the best one !
I am continuously surprised by the discouraging comments, especially by adults and mentors on this forum. FIRST is about encouraging these students to TRY things, think outside the box, see whats possible, yet this thread is full of the opposite.
There is a big difference between "we have not been able to figure out how to do it." and "it's impossible" or "don't even bother." Let's be constructive not discouraging.
DELurker
10-01-2014, 11:32
Team 20 has prototyped pneumatic system to propel the ball. We had absolutely no luck. The system barely got the ball in the air. :(
1370 did some testing last night. the 1-1/2" cylinder (1.7 factor) moved too slowly to launch and the 9/16" cylinder (0.2 factor) didn't have enough thrust. The students are interested in splitting the difference and going for a 1-1/16" bore cylinder (0.9 factor), but we would have to get one. :(
Right now, we're putting air punches on a back burner pending the outcomes of other ideas.
Sarakiro
10-01-2014, 13:01
If you are looking at a linear "punch" (actuation), your best bet (if you intend to use pneumatics) will likely be to use a wide bore piston to reset a highly tensioned plunger mechanism on guide or track. Just a thought.
Al Skierkiewicz
10-01-2014, 13:06
Brandon et al,
During inspection, launchers may have to demonstrated for "dry firing" to see if they are in fact safe with no ball present. Having no external hard limit for cylinders quite frankly scares me. While the working pressure is only 60 psi, a cylinder can impart quite a bit of force on the piston and the end assy with no system resistance. I have seen enough catastrophic failures to worry about this design choice. Please prototype with extreme safety in mind.
Brandon et al,
During inspection, launchers may have to demonstrated for "dry firing" to see if they are in fact safe with no ball present. Having no external hard limit for cylinders quite frankly scares me. While the working pressure is only 60 psi, a cylinder can impart quite a bit of force on the piston and the end assy with no system resistance. I have seen enough catastrophic failures to worry about this design choice. Please prototype with extreme safety in mind.
While a 3/4" cylinder with good flow to it moves pretty quick, and we always make strong efforts to work and design safely, I would be amazed if an unmodified COTS piston operated at less than 50% max psi recommended by the manufacturer (125psi max, operated at 60psi per FIRST rules) failed due to dry firing. This would be a major design flaw by the manufacturer. Now if we dry fired it at 125+ psi many times and it failed that's another thing. We will of course exercise caution but a failure of this type with no other damage or modification seems implausible especially given the reliability of our product manufacturers.
martin417
10-01-2014, 13:25
well my team original idea was to use pneumatic but we simply could not get the piston to extend fast enough to push the ball far enough. We even called are pneumatic guy to ask him if he had any cylinders that could open with such speed and force but he told us that he could not think of any way to do it. So i would say that to my knowledge there is no way of using pneumatic to shoot the ball in to the high goal, however it may be possible in the low goal.
Your best bet is to prototype some different shooters and pick the best one !
I can guarantee that it is possible to launch the ball into the high goal using only unassisted pneumatic cylinders. In 2008 we were able to fire the ~8 pound, 40" diameter trackball way farther than would be required for this 2 1/2 pound 24" diameter version
Al Skierkiewicz
10-01-2014, 13:51
While a 3/4" cylinder with good flow to it moves pretty quick, and we always make strong efforts to work and design safely, I would be amazed if an unmodified COTS piston operated at less than 50% max psi recommended by the manufacturer (125psi max, operated at 60psi per FIRST rules) failed due to dry firing.
Mike,
125 psi is the working pressure at which integrity with pressure is guaranteed. It does not relate to mechanical failure of the device with no load.
themccannman
10-01-2014, 13:56
I am continuously surprised by the discouraging comments, especially by adults and mentors on this forum. FIRST is about encouraging these students to TRY things, think outside the box, see whats possible, yet this thread is full of the opposite.
There is a big difference between "we have not been able to figure out how to do it." and "it's impossible" or "don't even bother." Let's be constructive not discouraging.
Most of us aren't trying to discourage students, were trying to save you from wasting your build season. 6 weeks is not enough time to try every possible method and pick your favorite. A large portion of the design process is brainstorming what is feasible and what isn't so you don't waste your time. We will be ready by week 1, and I hope we can get as many other teams as possible ready by then too.
LH Machinist
10-01-2014, 14:14
One method of shooting using pneumatics.
One method of shooting using pneumatics.
can you Explane how this works
Mike,
125 psi is the working pressure at which integrity with pressure is guaranteed. It does not relate to mechanical failure of the device with no load.
Hi Al, i understand that 125 psi is the working pressure at which integrity with pressure is guaranteed. I have never seen any documentation from the manufacturer or anyone else for that matter suggesting that this guarantee is under the condition that there is a minimum load applied to the cylinders. A mechanical failure of the cylinder, operated as intended and within the specified psi, unmodified and undamaged/not worn, would be a product or design failure by the manufacturer. These cylinders are designed to be operated under the specified pressure and are not subject to the condition of a minimum load to be safe. Yes they will actuate very fast (especially smaller diameter cylinders) but especially when restricted to 60psi (again less than 50% working pressure) we are well within the scope of intended and safe use specified by the manufacturer.
Animal Control
10-01-2014, 16:08
If you punch it too hard with too much pressure and not enough padding between the cylinder and ball you will puncture the ball.
cmrnpizzo14
10-01-2014, 16:14
can you Explane how this works
Essentially what you do is actuate the larger piston so that the air travels through the solenoid into the cylinder. The smaller cylinder is acting like a latch and is blocking the large cylinder from extending. Once the air is in the cylinder and the cylinder is supposed to be extended you retract the smaller cylinder out of the way ("unlatching" the large cylinder. Then the large cylinder will extend much more rapidly than it would have without the latch because the extension speed will not be dependent upon the air flow through the solenoid. It is basically a way to get around the air flow problem that many people experience with the solenoid.
If you want a more detailed explanation we did something like this on our 2010 bot. PM me and I can try to explain it better.
Dr.Gusta
10-01-2014, 17:17
Okay would something like the rough drawing below work? A ram is pulled back by a pneumatic piston, the surgical tubing wants to pull the ram back. To fire it the pressure in the pneumatic piston would be released allowing the surgical tubing to pull the ram out and hit the ball. The only thing I am really kind of worried about is the sergical tubing will loose a lot of force trying to pull the piston out even though there is no pressure. Thoughts? Ideas?https://docs.google.com/file/d/0B7jEnc-gvsaxRjhNTkxfVld2aEE/edit?usp=docslist_api
Dr.Gusta
10-01-2014, 17:39
There it should be fixed now. Sorry I forgot to make it public.https://drive.google.com/file/d/0B7jEnc-gvsaxRjhNTkxfVld2aEE/edit?usp=sharing
Steven Smith
10-01-2014, 18:04
If I understand the drawing correctly, you would essentially have an outer tube to contain both a pneumatic cylinder and a firing pin. The firing pin is mounted to both the end of the pneumatic cylinder, and a bolt that travels in a slotted groove in the outer cylinder. The pneumatic cylinder compressed, extending the latex, and then is "triggered" by allowing the pneumatic cylinder to extend again (possibly driving it back into the firing pin, but with the assist of the latex tubing). This essentially looks like a pinball launcher to me.
As noted before, two issues you may struggle with are:
-Insufficient speed on your ramming arm, as larger cylinders can often move more slowly
- Too much speed on a relatively small ramming head, which at best will lead to lower accuracy, or at worst could damage the ball.
I'd mock up something simple and see where it gets you (prototype). If you like the idea of the pinball tube, I think you may get more "oomph" from actuating it from the outside, with a mechanism that can run the bolt connected to the latex tubing backwards until it reaches a breaking point... slip off to allow the shot, then catch it back at the starting point.
I do think you would be wise to consider a few other designs that might be simpler (backup plan), but it might still be worth prototyping your original design to see what comes of it.
Steven
Dr.Gusta
10-01-2014, 18:11
I think you slightly miss understand but you have the basics down. The piston will pull the surgical tubing tight and the ram into the arm. In order to fire both sides of the piston will be opened thus causing the sergical tubing to actually pull the piston open. So all of the firing power comes from the tubing and none from the piston. Hope that makes more sense.
Dr.Gusta
10-01-2014, 18:29
So the pneumatic piston will have no pressure in it at all allowing the sergical tubing to retract and fire the ball.
Steven Smith
10-01-2014, 19:31
I might be missing your intent again, but I think you might be underestimating the impact that keeping your cylinder connected will have.
PIC (http://imgur.com/TzlFGg3)
When you compress that cylinder down to (edit lol: umm "Rooster") your firing mechanism, you will have ~60psi (or less if you regulate it further down) holding it in that position until you go to fire it. When you fire it, yes the latex tubing will pull it out, but it is forced to exhaust the entire contents of that piston chamber either back through the solenoid valve (worst case) or through a seperately actuated solenoid valve Tee'd in at the cylinder. Either way, you are limited to an 1/8" valve size, which means it takes a non-zero amount of time to exhaust it.
Essentially, your piston will act as an air damper for your firing mechanism. This is why many people considering pneumatics as a way to store energy in a spring (or otherwise) are looking to use a "trigger" that will allow the latex tubing to fire without the cylinder slowing it down.
Thanks,
Steven
Dr.Gusta
10-01-2014, 19:41
So ay that makes a lot of sense. That is what I was kind of worried about. So like a Solenoid will be needed to "pull the pin" and fire it then the piston will extend again and the pin put back in to the shooter again. I like that. Time to prototype a surgical tubing launcher then incorporate pneumatics later.
Al Skierkiewicz
13-01-2014, 10:30
Essentially what you do is actuate the larger piston so that the air travels through the solenoid into the cylinder. The smaller cylinder is acting like a latch and is blocking the large cylinder from extending. Once the air is in the cylinder and the cylinder is supposed to be extended you retract the smaller cylinder out of the way ("unlatching" the large cylinder. Then the large cylinder will extend much more rapidly than it would have without the latch because the extension speed will not be dependent upon the air flow through the solenoid. It is basically a way to get around the air flow problem that many people experience with the solenoid.
If you want a more detailed explanation we did something like this on our 2010 bot. PM me and I can try to explain it better.
Cam,
The cylinder moves out to the machanical stop but it doesn't have any higher pressure air or greater volume. When the mechanical stop is removed, air still needs to flow behind the piston and that air passes through the fittings as if the primary valve was opened. Or am I missing something?
jijiglobe
13-01-2014, 10:48
Someone on my team talked about using multiple solenoids to actuate a single piston. This would bypass the problems of solenoids not letting enough air through in enough time. Does anyone know if this is a thing you can do? It seems a little sketchy.
MechEng83
13-01-2014, 10:57
Someone on my team talked about using multiple solenoids to actuate a single piston. This would bypass the problems of solenoids not letting enough air through in enough time. Does anyone know if this is a thing you can do? It seems a little sketchy.
R90: The outputs from multiple valves may not be plumbed together.
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