arx modelling: where to start

[rina]

Hi everybody,

I'm a beginner in modelling with Labview (before I had done it in Matlab under syst ident tool box). Where should I start in Labview? I was trying study example Estimate Polynomial Models.vi. But it seems like I dont undertsnd. I hope someone can help me.

Thanks!!!

[Bob_Schor]

Sounds like you need to learn some LabVIEW.  There are numerous Tutorials (you'll need to spend a little time, but I'm sure, from your MatLab experience, you know that there will be a learning curve).  Do as many of the exercises as you can -- you need to get used to programming "graphically".  Try to study "good programs" to see what makes them tick.  Don't be afraid to look at the Examples that ship with LabVIEW, including the Templates that can be found in the Getting Started with LabVIEW initial Splash Screen (they may be a little more complicated than you need, but they do represent NI's attempt to embody Good Practices).

One list of tutorials can be found in the upper right corner of the LabVIEW Forum's main page.  Another, from the "Unofficial Forum Rules" is shown just below this line:

Looking For Free Training

Many times new users of NI hardware or software just don't know where to start.  They will ask a question but without knowing the terms, or the intended purpose, they will not be able to form a proper question.  Here are some free training tools primarily focused on LabVIEW and NI hardware to help get started.

NI Learning Center

NI Getting Started

-Hardware Basics

-MyRIO Project Essentials Guide (lots of good simple circuits with links to youtube demonstrations)

-LabVEW Basics

-DAQ Application Tutorials

-cRIO Developer's Guide

Learn NI Training Resource Videos

3 Hour LabVIEW Introduction

6 Hour LabVIEW Introduction
Self Paced training for students
Self Paced training beginner to advanced, SSP Required
LabVIEW Wiki on Training

The best way to learn, is to follow the tutorials, then ask lots of questions. 

Bob Schor

[nyc_(is_out_of_here)]

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@Bob_Schor wrote:

Sounds like you need to learn some LabVIEW. 

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He/she has been "learning" LabVIEW since 2010.  That's a long time.

[rina]

Sorry..very sorry. Some misunderstanding here.

Yes, I used to use the labview before but not system identification tool box. And now I want to generate ARX model. Seems like I can produce the model  but now I have new problem. Anyway MANY THANKS for your suggestions.

my questions are:

1. how to identify the best coefficients?(in matlab they produce the best fit and FPE value for this purpose)

2. Do I have to use "SI Estimate Orders of system model.vi" instead of "SI Estimate ARX Model.vi " ?

many thanks!!

[Bob_Schor · Accepted solution]

I've done some modelling (typically fitting transfer functions and using models to suggest the system producing the observed system response), but was not familiar with ARX Modelling.  However, a little Web searching led me to several LabVIEW references (probably more are in LabVIEW Help), including this one.  I don't happen to have the System Identification Toolbox installed on my machines -- presumably this is part of your installation (and if it isn't, you need to obtain it!).  How's your math?

Bob Schor