MY team is thinking about using pneumatics this year, but doesen’t know how to operate it.
Our question is how do we regulate, or control the amount of air it gives out at a given time?
I’m assuming you are using single acting pistons so you you can either have it extend or retract, no in between. You can regulate the speed but not the amount.
Delta
Are you asking if you want say only 50psi to go to a cylinder instead of 100psi?
If so i think you can use the regulator that comes with the kit there should be a knob that you can turn to adjust the pressure.
If you are asking how to control the solenoid valves we use EasyC V4 and all you need to do is use the
“Joystick to Digital Output” block in “Joystick” and drag it into operator control. Then plug the solenoid driver wire into a port from 9-12 (this is your digital output ports on both the PIC and Cortex unless you changed it in the program)
What do you mean by regulate speed?
Just pretend if I used a button to activate the pneumatics so it will either go extend or retract. Is there a way to program the pneumatics so when I press the button that it extends the same amount every time, and retracts the same amount?
So you’re asking if theres a way that you can extend a pneumatic cylinder say one inch instead of the full 2inch stroke?
Yes that is what I am asking.
Yes there is a way, However I forget how it all works. So I’ll get back to you on that tomorrow.
Pistons are either getting air from the tank through the solenoids or they aren’t. You can use hard stops or pressure regulators to limit movement and force, but a solenoid is just open or closed.
this is possible, but it is easier to just mount the piston differently to suit the distance needed (have a gap between end of piston and what firing at). hard stops mounted on the piston are possible, but annoying to make
Ok I have deliberated and I might have an answer for you, However with VEX materials stopping a cylinder proves problematic if you want an accurate position.
Ok so to get started I’ll list Materials
For this method of stopping the cylinder mid stroke you will need: (per cylinder for each separate system)
1 accumulator
2 pressure regulators
2 solenoids
fittings
tubing
and as many double acting cylinders you can/want to use or afford
The image above is a quick sketch of what you would have to do to stop the cylinder, however there is a catch.
On the bottom end of the cylinder you have to regular the pressure to a lower PSI and the top end of the cylinder
So if you look at the drawing R1 would have to be something like 90 psi and R2 would have to be the full 100 psi
This would push the cylinder back and if you had a bit of patients you could probably set find the distance you wanted it to extend by playing with the pressure after it settles. Now this is all theoretical so don’t take my word on it but it should work. How reliably is also a different story but it does basically stop the cylinder mid-stroke if done correctly.
If you have any more questions just go ahead and ask.
- Andrew
The main way to get a cylinder to have less throw (1 inch instead of 2) is to put a spacer on the piston so it only goes “back in” one inch.
that is definately the easy way to do it
I think Andrew’s system should work…but
there are lots of mechanical ways to reduce 2 inches of movement to one inch of movement…
less work and theoretically more force …
and of course the other direction works too…
you can make something move much further than the two inches if your desigh doesn’t need the full force.
We use several sets of pneumatics here and the biggest limitation often turns out that you only have a limited number of “movements” before you run out of pressure…