# Pneumatics Issues + Progress Update!

So we’ve been working on the pneumatics for a while, but we’ve ran into a couple of issues. If anyone could help (including @Got a Screw Loose )… basically the code doesn’t work and the pneumatics dont shoot in far/ strong enough

First of all we can’t get the code working (WE’RE USING ROBOT C AND WE STILL HAVE VEX LEGACY CORTEX). You see our pneumatic cylinder doesn’t have a spring that pulls the piston back so we need to use code to do so. We used the following video (code is at the end) and basically copied the code to see if it worked on ours it didn’t… we also did the same hardware setup (hardware worked)… why didn’t the code work though?

So at least the hardware was working, so i just decided… well let me fill it up with air with an bicycle-pump and then manually toggle the switch to stop or let airflow and thus shoot the piston … However, the ball doesn’t fly very far (SEE Video 2 below)… I think its because there is a very small point of contact?.. or is there not enough pressure because we’re using a hand-pump?.. whats the reason you think??
We have to use a bicycle pump because even if we have those electronic generators that can fill it with air we cant take that to the competition because it uses 240v and you can’t exactly use a portable battery for that or use an outlet at the competition (we compete in Japan it is 120v in outlets i think)… so if you think pressure is a problem then how can we use an bicycle pump but have adequate pressure up to 100psi limit.

If the problem is the point of contact how do you suggest we fix that… we added a thick high strength gear to the end of the pneumatic piston to have a wide area of contact, but that did literally nothing.
I recall there is a formula for force… (Cross Sectional Area of Cylinder) x (Internal Air Pressure) = Force

Video 2 (is in SLOW MOTION) (video of our pneumatic system): https://drive.google.com/file/d/1IsO1F2RNu43qAaf-hqNiM7_QIDlh_Mlv/view?usp=sharing

@Got a Screw Loose

I dont think the punchers are strong enough to launch a ball. I dont have any experience with them, but from what I understand they are very underpowered.

This was my concern from when I spoke to you guys early season. The pneumatic pushers are kind of slow, and I don’t think there’s a legal way to increase their output.

This could go back to my idea of increasing the contacting pushing surface. Giving this surface a single layer of rubber bands or antislip might help with the elastic collision we are going for. Might.

The only other real solution I see is to make some sort of linkage to increase the speed of the contacting point, and then have the pneumatics power that. However, I would have no idea what that would look like, nor do I know how bulky it would be. It would almost just be easier to build a traditional puncher and put that in place of your pneumatic piston.

I’ll be thinking about this, but I’m not sure there is really a good way to make this viable.

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Okay, the only linkage I could come up with. I modeled it with IQ pieces, but you get the point. It would take up about 1.7x the amount of space you currently have in the arm, I think.
I spaced stuff out more than necessary for clarity.

The first two pictures are of the side with the pneumatic cylinder. That’s the thing I encased with the black pieces. The last one is of the side with the striker. I’m sure someone else can probably improve on this, but it’s all I’ve got right now.

As far as the code, can you just wire it up and do a Dgtl(x)==1 command? I’m not sure of the exact syntax, but it’s about the simplest line you could do to give it the command.

Does anything on the robot work? Dovthe wheels drive? Maybe there’s an issue with the Cortex or the port you have it wired into. Move the wire to a port you know works, then try again.

Is the latest firmware on the Cortex? I would try to do a Firmware Download, because there might be some operating system bug.

Before any dramatic rebuilds, let’s make sure you have a way to actually power the thing.

I may be the only one, (besides TitanRey15) but I really want to see this work. I dug up the first thread on this topic for others to get more information to help. https://vexforum.com/t/pneumatic-shooting-system-doubts/50048/1

@Got a Screw Loose Cortex is fine and firmware is updated. Have you seen the code at the end of the video1 i put up… we have copied that code so where do you want us to add what you think we should add? Also when you say make the surface elastic which surface do you mean the ball or the puncher? obviously the puncher right? Can the speed be adjusted in the code by the way?

@Gameoa Also punchers should be strong enough as 11 people are using them according to a poll done on the vex forums on what type of shooting system peeps are using (i dont know where cant remember)… and see the formula down below the force can be quite high if there is enough pressure and contact point
My coach insists it is strong enough and that we have either not wired it up correctly or we need to first do the code for it to work properly??

Do you remember if that poll specified pneumatic puncher? A lot of teams are using slip gear punchers because of 574C’s awesome tutorial.

I have not had a chance to look at the pneumatic tutorial vid. I’ll take a look at that later when I have the block of time to do so.

The seeing as you can’t modify the ball in any way shape or form, the puncher’s surface, obviously. I think @callen has a better grasp of the physics behind it, if he’s willing to help.

What I built is big and bulky. I’m not sure if you have the space for it, but it would ideally go inside of your angling arm. That linkage, in equivalents, will multiply your speed by 7. But I don’t think you can adjust the speed of the pneumatic cylinder. Don’t add what I built yet and let’s try to get the code and wiring figured out. I’ve never played with pneumatics, (as you know) so I might not be that huge of a help.

Edit: I looked at the code in the video and don’t see any major problems. I take it you’ve obviously checked for random things such as missing a semicolon, not opening/closing the while loop, etc. I would have used the same syntax and stuff when coding mine. Maybe post your code so that we can take a look at it for something you might’ve missed? Do you have diffierent apparatus you can test it with and it’s not just a bad solenoid?

How about replacing the solenoid with an LED light? I think it would behave the same way, and therefore you might be able to differentiate between the code being the problem and the pneumatics being the problem.

Maybe try to take the bump switch out of the equation. Delete that command and the while loop, and just set the solenoid to 1, wait a couple of seconds, then set it to 0. Remove as much error as possible.