System Identification - LabVIEW and Matlab

[Pablo Guevara]

Buenas a Todos, miren Comunidad NI Necesito un favor grandísimo... trataré de redactarlo en Español y en Ingles, aunque aclaro que soy colombiano y obviamente mi lengua materna es Español.

//Español//

Alguno de Uds. me puede ayudar a hacer una Identificación y Estimación de Parámetros, de unas plantas (que son básicamente filtros pasa bajas a frecuancias muy bajas, diseñados a 3 Hz.), con entradas de cada una de estas plantas de señales Escalón o Paso, Impulso y Seno (en un Barrido de Frecuencia de 1 Hz hasta 17 Hz). Estoy trabajando con la USB 6008 para generar y adquirir los datos más fácilmente.

Para la Identificación de los parámetros me baso a la par de LabVIEW con Matlab, ya que ambos programas pueden rabajar muy bien simultaneamente. Envio la señal de LabVIEW y recibo de las salidas de las plantas con el Simulink de Matlab, en el Toolbox Data Adquisition la caja Analog Input. En el Modelo de Simulink capturo cada uno de los datos en una caja llamada To Workspace en un Array. Todo trabaja muy bien!!!

La ayuda era para ver si alguien podía colaborarme y ayudarme a sacar cada uno de los aspectos para la correcta Identificación de los parámetros:

Ganancia

Polos

Función de Transferencia

Tiempo Muerto

Sincronización entre la señal y la captura de datos, etc.

No es sencillo ... pero como hay gente tan brillante, se que lo podemos desarrollar.

// In English//

" I need is basically it is to do one - Identification and Estimation of Parameters, for a few Plants of First and of The Second Order (Low Pass Filters) in Real  Time - to each of these plants, I deposit three types of signs Step, Impulse and Sine (with a sweep of frequency of 0.5 Hz up to 17 Hz).  

Now, I am working with the National Instruments Ref. USB 6008 (for facility of generating the sign and of acquiring it). Up to the moment I generate very well three signs in a program Implemented in LabVIEW, these signs come to the plants... of the exit of the plants I get for a port of the Card of Acquisition of Information USB 6008, and am employed without any problem at Matlab and Simulink.

Matlab with the Simulink facilitates everything to me:

1. It recognizes me the external device (Data Adquisition Toolbox, with the option Analog Input).

2. The idea is that across the To Workspace, I store the information in an Array.

The problem and the complex thing of this, it is the part of the program that across the Arrangement of the To Workspace, could come to the Function of Transfer and that of here it transports (the poles, gain, death time, synchronized between device signal and program, transfer function, etc...) ".

[Barp]

Pablo,

First of all, please verify with your university that you have access to a LabVIEW toolkit called System Identification Toolkit and the Control Design Toolkit.

If you have this toolkit, all those parameters that you are looking for could be easily obtained. Depending of the version that you have (latest is System Identification 4.0 for LabVIEW 8.2 and later), you can just acquire the signal from the DAQ board and pass it through a specific VI and your system will be identified; it provides you with a transfer function using the "SI Estimate Transfer Function Model.vi" and could obtain the parameters using another toolkit call Control Design Toolkit, which can give you the . It also has grey box identificaition that allow you to obtain specific coefficients. Notice that all can be done within LabVIEW, making it easier to work the results. Below is a simple example to what kind of code you would need if you had System Identification and the Control Design Toolkit.

Notice that you just need to obtain the Stimulus and the Response signal and there is examples in DAQmx that does this operation for you.

Hope this helps.

Message Edited by Barp on 11-16-2007 08:07 AM