PID block turn off anti windup

[Jason93]

I’m using the pid block in lab view for controls education. I’d like to demo anti windup and with and without it. However I think it knows my mydaq isn’t +-10v so it always has antiwindup enabled. Do I need to make a home made pid block?

thanks

jason

[aputman]

Let me preface this by saying I'm not a PID expert.

But looking around the web and in the help file, the anti-windup is applied thru the output range.

Looks like you're going to need a custom PID VI. 

If my understanding of this is correct, it should just be a matter of enabling/disabling the InRange and Coerce functions. 

[GerdW]

Hi Jason,

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However I think it knows my mydaq isn’t +-10v so it always has antiwindup enabled. Do I need to make a home made pid block?

---

Who is "it" and what exactly does "it" know?

What is your myRIO when it is not "±10V"?

LabVIEW comes with a plain/simple "PID" and with a "PID Advanced" function.

Which one are you using?

Which one has a problem with "enabled anti-windup"?

(I'm using mostly the PIDAdvanced and I'm very happy with it.)

@aputman:

The Anti-Windup uses the OutputRange to limit the internal integral error value, so it's not "just an InRangeAndCoerce" applied on the PID output.

[Jason93]

"it" is the PID block. I'll investigate more when I get to the lab. But it seems to know that my myDAQ has a +-10volt output range so it automatically will do integrator antiwindup when the commanded output goes above 10v. I am a PID expert but what I'm not is a Labview expert and don't know always what is going on "under the hood"  I'd prefer to let the integrator windup to 100v if that is what the gains and error do. But I do recognize in real practice there is no reason to do that.  But I'm trying to teach a student the difference and how the actual antiwindup algorithm works.  I can make my own custom block but I figured I'd ask the community who have more experience with the Labview blockset.

JAason

[GerdW]

Hi Jason,

what have you set as output range? This is what is used for anti windup...

It would be easier to help when you would attach your VI!

[Jason93]

thanks

The VI isn't on the PC. I'm pretty sure if I set it above +-10V the VI will yell at me claiming my DAQ device cannot go above 10V (I'm trying to recall). I'd like it to set it to +-INF and let it windup, even though it cannot output greater than 10V.

Jason

[GerdW]

Hi Jason,

the PID function alone will not "yell" at you as it doesn't know you are using a certain DAQ device.

So the VI around the PID function has to handle this ±10V limitation…