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From: Dan Stephenson on 11 Nov 2008 00:15
LabVIEW has lots of built-in controls and filters, but I want my own.

I want to send data I collect through a transfer function of my own
specification, such as a second order where I can specify frequency and
damping. Or even something much higher-order.

But I cannot figure it out. I played with the H(z) discrete transfer
function, but there is no output from it, even when I specify just a
1/z lag. And the H(s) doesn't even drag out of the palette.

Please help, I'm new to LabVIEW. I ultimately want to implement a
feedback control systems on a motor with a rate loop and outer position
loop. I should be able to easily implement such a super-simple thing,
but heck if I can figure it out.

Please post or email,
--
Dan Stephenson
Photos, movies, panos from the Europe, USA, plus N.Z.:
http://homepage.mac.com/stepheda

(remove nospam from email address to reply via email)

From: hrh1818 on 11 Nov 2008 11:41
On Nov 10, 11:15 pm, Dan Stephenson <stephedanos...(a)mac.com> wrote:
> LabVIEW has lots of built-in controls and filters, but I want my own.
>
> I want to send data I collect through a transfer function of my own
> specification, such as a second order where I can specify frequency and
> damping.  Or even something much higher-order.
>
> But I cannot figure it out.  I played with the H(z) discrete transfer
> function, but there is no output from it, even when I specify just a
> 1/z lag.  And the H(s) doesn't even drag out of the palette.
>
> Please help, I'm new to LabVIEW.  I ultimately want to implement a
> feedback control systems on a motor with a rate loop and outer position
> loop.  I should be able to easily implement such a super-simple thing,
> but heck if I can figure it out.
>
> Please post or email,
> --
> Dan Stephenson
> Photos, movies, panos from the Europe, USA, plus N.Z.:http://homepage.mac..com/stepheda
>
> (remove nospam from email address to reply via email)

If you have a recent version of a full Labview Development System you
can use a Mathscript node to implement transfer functions. A
mathscript node can execute most Matlab functions. Labview's built in
help provides a lot more information on Mathscript nodes and you can
also search the examples that come with Labview for examples that use
mathscript nodes.

Howard
From: Dan Stephenson on 11 Nov 2008 21:04
On 2008-11-11 10:41:24 -0600, hrh1818 <hrhan(a)att.net> said:

> If you have a recent version of a full Labview Development System you
> can use a Mathscript node to implement transfer functions. A
> mathscript node can execute most Matlab functions. Labview's built in
> help provides a lot more information on Mathscript nodes and you can
> also search the examples that come with Labview for examples that use
> mathscript nodes.
>
> Howard

Thanks Howard I've thought of that and for low order it would be easy.
You mean it'll just handle all the states for you?

But I still find it hard to believe LabVIEW cannot implement such as
super basic capability like sending the data acquisition signal through
a transfer function of my own specification.

--
Dan Stephenson
Photos, movies, panos from the Europe, USA, plus N.Z.:
http://homepage.mac.com/stepheda

(remove nospam from email address to reply via email)

From: hrh1818 on 11 Nov 2008 22:52
On Nov 11, 8:04 pm, Dan Stephenson <stephedanos...(a)mac.com> wrote:
> On 2008-11-11 10:41:24 -0600, hrh1818 <hr...(a)att.net> said:
>
> > If you have a recent version of a full Labview Development System you
> > can use a Mathscript node to implement transfer functions.  A
> > mathscript node can execute most Matlab functions.  Labview's built in
> > help provides a lot more information on Mathscript nodes and you can
> > also search the examples that come with Labview for examples that use
> > mathscript nodes.
>
> > Howard
>
> Thanks Howard I've thought of that and for low order it would be easy.  
> You mean it'll just handle all the states for you?
>

Your terminology has me confused. What do you mean by it will handle
all the states for you?

> But I still find it hard to believe LabVIEW cannot implement such as
> super basic capability like sending the data acquisition signal through
> a transfer function of my own specification.

But that is exactly what you can do with a Mathscript Node. You can
put a transfer function that meets your specification in a Mathscript
Node, send your data acquisition signal to a Mathscript Node and get a
filtered signal at the output. Labview also has the capability to
implement FIR and IIR Filters. You really should think about using
either a FIR or a IIR filter as your data acquisition signal is a
sampled signal. It is not a continuous signal. The full version of
Labview comes with a lot of examples of FIR and IIR filters.
Note by transfer function I mean your filter is specified as a ratio
of the powers of S in the numerator and denominator. By FIR and IIR I
mean you filter is specified as the ratio of the powers of Z^-1 in the
numerator and denominator.

Howard

>
> --
> Dan Stephenson
> Photos, movies, panos from the Europe, USA, plus N.Z.:http://homepage.mac..com/stepheda
>
> (remove nospam from email address to reply via email)

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