Integrator/Derivative in Advanced Control Toolbox

[Sima]

Hello,
I'm trying to implement a nonlinear control problem. I had written it in Matlab/Simulink, but I prefer to have it in LabVIEW, particularly because I'm going to do data acquisition. I thought it should be similar to the way I have my system and controller drawn in Simulink, so I used the Integrator and Derivative VIs, except my code isn't working like it should. The time step "dt" also seems to have all kinds of effects on my system. The output of the system goes all over the place. Any advice would be appreciated! Does anyone have an example VI to share of a nonlinear state-space system implemented in LabVIEW this way - using the Integrator and Derivative VIs?
Thanks,
Sima

[Bassett_Hound]

Sima,

I search the NI Developers Zone and was unable to find any example programs that use the Integrator and Derivative VIs for Non-Linear State-Space Systems.  I did however,  notice there were a few examples in the NI Example finder that might be of use to examine if you have not done so already.  If you launch LabVIEW select Help from the menu and then Find Examples > Toolkits and Modules > Control Design.

If you could describe how your application is not working properly in more detail it would be easier to suggest how you might go about fixing it.  What kind of effects does the dt value introduce and what are you expecting?

Steven B.

[Sima]

Hello Steven, thanks for your reply. I did use the examples as a reference to simulate my system in LabVIEW. Basically all I did was insert the Integrator and Derivative VIs where I needed them. But, what about solvers? In Simulink, you specify which ODE you want to use, like ode45. Am I missing something here? Something in LabVIEW??

[Bassett_Hound]

Sima,

If you are using LabVIEW Full or Professional Development versions there should be a set of ODE solver VIs provided.  I believe the ODE45 provided by Simulink uses a Runge-Kutta method.  There is a LabVIEW ODE solver based on the Runge-Kutta method located in the Analyze > Mathematics > Calculus > Differential Equations as well as several other methods available. 

Steven

[Sima]

Hi Steven, I'm going to try using the Simulation Interface Toolkit and/or the Simulation Module. Maybe I won't have to rewrite all my Simulink models in LabVIEW. Thanks for your suggestions.

[Bassett_Hound]

Sima,

That is another possible option.  Let me know how it goes with either of the toolkits.

Steven B.

[Bassett_Hound]

Sima,

The LabVIEW Simulation Module would be an excellent option and it sounds like it would fit your application.  I have attached a link for a introduction to LabVIEW Simulation Module and the LabVIEW Simulation Users Manual for you as well.

LabVIEW Simulation Module Tutorial
http://techteach.no/publications/labview_simulation/

LabVIEW Simulation Module User Manual
http://digital.ni.com/manuals.nsf/websearch/731861397AA0ACFE862570AB00734862

Hope this helps.

Steven B.

[Sima]

Thanks Steven.