pneumatic cylinder position control

[Simo91]

Bye to all,
sincerely I am a little acerbo in the pneumatic systems (small systems with Boolean logic, but beyond that zero), and therefore I look for advice:

My problem is to make the system "dynamic" in the photo (Annex), in fact placing 2 identical opposing cylinders you create the balance in the middle.

an idea (if feasible) is to control in place the 2 stems of the cylinders, so as to make it dynamic, but it is not propius that fishes plow:frown:

Thank you in advance

 

[cacciatorino]

an idea (if feasible) is to control in place the 2 stems of the cylinders, so as to make it dynamic, but it is not propius that fishes plow:frown:

Forget it.

if you have no particular reasons to use the tire (esplisive environments?) uses an electrocylinder.

As the air is highly compressible, what you want to do is very difficult. It's easier to control the force with a servovalve, but to control the position I find it impossible.

 

[Simo91]

Okay, at least now I know what way I can take.
I have searched for information about electrocylinders, and if I have not misunderstood the inside is composed of a ball recirculation screw, which is electrically controlled and can perform dynamic shifts, (in practice controlled in position).

I had noticed the compressibility of the air, but my colleagues insist on the tire.

Thank you so much!

 

[cacciatorino]

and if I have not understood badly the inside is composed of a screw recirculation of spheres, which is electrically controlled and can perform dynamic movements, (in practice controlled in position).

That's right!

on a machine we have mounted automationware material, have the flanges of attack equal to those of the corresponding tire cylinders of equal size.

 

[Fulvio Romano]

Bye to all,
sincerely I am a little acerbo in the pneumatic systems (small systems with Boolean logic, but beyond that zero), and therefore I look for advice:

My problem is to make the system "dynamic" in the photo (Annex), in fact placing 2 identical opposing cylinders you create the balance in the middle.

an idea (if feasible) is to control in place the 2 stems of the cylinders, so as to make it dynamic, but it is not propius that fishes plow:frown:

Thank you in advance

I wouldn't call "dynamic" a system like that. in control theory a dynamic system has a very precise meaning, that its output is not uniquely determinable from the input.

That said, the double pneumatic cylinder seems to me a design error. You want to do the same with the tire you need a pneumatic cylinder and a spring on the other side. or better still a single-stable cylinder (so with integrated spring). more obviously a position sensor on the stem. you can use a pid for control.

the pid (with zero drift to suppress the noise and integral hypersmorzate on the proportional to avoid oscillations, at least in the first approximation) takes the difference between the position setpoint and the position sensor value, and in the pilot output a proportional valve on the air supply.

if instead of a proportional use an open/closed valve you need a bang bang control...you can do it, but it takes a little more sophisticated control tools.

 

[stefanobruno]

If you don't specify what you have to do, your real application, I think we're gonna disappear a bunch of cretins.

if your application were this: http://www.cad3d.it/forum1/showthread.php?t=30058, apart from the good rule not to duplicate the questions, a pneumatic cylinder with passing stem could be enough, used only as a dampener with the two connecting chambers between them.
If it works, badly and in one way, the spring, with the cylinder you are fine.

 

[Simo91]

stefano you are right the purpose is that in the link, I apologize for repeating.

I've never seen the cylinder, I know how it works normally, but I don't understand the operation well with the 2 connecting rooms, would you explain it to me for pleasure?

I understood the concept, and if I'm not mistaken is that of a retroactive system. the purpose is that of the compensation system, and the operators working on this system identify the working pressure. the question is, would it be feasible to perform the system retroacted with pressure instead of position? ?

Thank you all, you're giving me a big help! !

 

[Fulvio Romano]

I understood the concept, and if I'm not mistaken is that of a retroactive system. the purpose is that of the compensation system, and the operators working on this system identify the working pressure. the question is, would it be feasible to perform the system retroacted with pressure instead of position? ?

It doesn't make much sense. Maybe I didn't understand the problem well, but if you have to control the position by acting on the pressure, then you can use a control system, but if you have to control the pressure by acting on the pressure itself... the control is useless, right?

 

[stefanobruno]

I've never seen the cylinder

I'll attach you a cylinder figure.
If you connect the two chambers of the cylinder by putting flow control valves, you get a device that damps the movement both in one sense and in the other, like the two opposing springs but with a fairly constant force throughout the race.
He's a ground regulator.
There are also those who are born specifically for this activity: http://www.diottalevi.it/330-regolatori-idraulici.htmlciao.

 

[cacciatorino]

Sorry, but at this point I'm in doubt about what you're looking for.

1) if you need to check the location:
electrocylinder or assimilar

2) if you have to control the force:
cylinder + servovalve or cylinder+pressure regulator + tank in line

 

[Simo91]

the original idea was to use a controlled cylinder in position (electrocylinder), to be used as a mobile wagon and through a control that uses as an input signal the working pressure of the arm and controls the position of the cylinder.
I have performed tests today with an electrocylinder sent in record times but for the processing we do (swimming and deburring) the control is too slow.

with the cylinder I should find the way to do it also advance.