Simulation/Software

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Toro's Avatar (by Gravatar)Toro posted on
May 27, 2008, 11:04 pm
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Hello to all.

In a previous project I captured plenty of process data, like setpoints,
measurements, PID output, Lead/Lag output, and many more points. I import
selected data points in Excel, I generate similiar algorithms in Excel
(like PID or Lead/Lag and etc.) that simulate a loop or two similiar to the
logic that generated the data, and run a macro. I compare it to the
captured data and when outputs match I know the code is a match. I then
inject a transient by increasing the measurement or setpoint or other and
monitor output initial behavior. I also use it to change PID gains and to
get a an idea of how controller will initially behave or how output behaves
at steady state.

Question, doing this in Excel is very tedious because PID controller and
others require previous data and the worksheet gets big. Is there software
out there tailored for this? I want a software that will allow me to
generate my own code and inject data from a text file and also capture the
calcualted data? I don't want to spend much time putting this test
together, I want to spend most of my time evaluating the data. Any help is
greatly appreciated.

Thanks

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pnachtwey's Avatar (by Gravatar)pnachtwey posted on
May 27, 2008, 11:51 pm
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Re: Simulation/Software



try Scilab.  It is free.
http://www.scilab.org/
There is a user group
http://groups.google.com/group/comp.soft-sys.math.scilab/topics?lnk=srg


There are other scientific or engineering software math packages.
Octave is free too.
Matlab, Maple, and Mathematic cost money

Peter Nachtwey

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Rich Webb's Avatar (by Gravatar)Rich Webb posted on
May 28, 2008, 9:25 am
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Re: Simulation/Software



On Tue, 27 May 2008 20:51:44 -0700 (PDT), pnachtwey


See http://www.scientificweb.com/ncrunch/ncrunch5.pdf  for a comparison
of several packages. Octave was not included in the latest run.

--
Rich Webb     Norfolk, VA

pnachtwey's Avatar (by Gravatar)pnachtwey posted on
June 1, 2008, 5:45 pm
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Re: Simulation/Software




That article was interesting but not as informative as it good be.
There were some very important comparisons that I think are important
and not addressed in the article.
1. How the programming is done.  To be fair the article done mention
the programming style but it doesn't really show the difference.
2. No mention is made of symbolic processing.  I can't do without
symbolic processing.  Mathcad can do symbolic processing but even a
free package like Maxima can out perform Mathcad.
3. Output.  It is nice is the output can be used to generate books or
magazine articles.  The file type is important but the quality of the
output is even more important.  Mathcad claims to generate html but
the idiot that generated the html used Microsoft \ instead of unix //
in the file paths so the Mathcad generated html files must be hosted
on a Microsoft server.  Linux servers can't find the image files.  To
fix this I must use and editor to replace the \ with /.

I have Mathcad now but I have "out grown" it and am looking to buy
Maple or Mathematica.  Mathematica looks like the more full featured
product but the programming looks awful compared to the Pascal like
Maple.  However, I like the Mathematica Viewer.  The user must
download a player but then the Mathematica program variables can be
changed by the user.  I am still investigating Maple to see if it has
these features.  I am torn between the two.  On the sci.math.symbolic
use group there is a person that finds bugs in both Mathematica and
Maple with equal ease.   I don't want to be trading Mathcad flaws for
Maple or  Mathematica flaws.

The point is that the table based evaluation doesn't tell the whole
story.

Peter Nachtwey



Kelvin Hales's Avatar (by Gravatar)Kelvin Hales posted on
May 28, 2008, 3:21 am
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Re: Simulation/Software



..Is there software

<http://www.mathworks.com/products/matlab>




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Freelance Embedded Systems Eng's Avatar (by Gravatar)Freelance Embedded Systems Eng posted on
May 28, 2008, 9:53 am
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Re: Simulation/Software



Toro wrote:

Scilab and Scicos are open source packages that first come to mind.
However, if you are comfortable with using Excel for analysis, then
you could use VBA macros to interface to a DLL and then do all of
the tedious work in another language like "C".  Either way, you still
have to do your own development.


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