transfer function and error signal

[yaauldgoat]

Hi
I have a transfer function something like (s^2+3s+5 / s^2+s+1 ) which is being generated as a string. however i need to multiply it by a constant number, error signal. Like control where the transfer function is multiplied by the error signal. how can I do this in Labview?

[Steven Bird]

Hello Yaauldgoat,

I have looked into this and the best way bar far is to use the control design toolkit that can be purchased for LV. (See attached screen shot of the toolkit being used to implement such a transfer functon).

You could also build the laplace functions yourself and there is a realize laplace function. You could also do this in matlab but again your will need the simulation toolkit for labview.

If your good with maths, you could possible reduce the transfer function to a difference equation and implement it using shift registers see below:

http://zone.ni.com/devzone/conceptd.nsf/webmain/2f266590b802fefd8625686500609588?OpenDocument


I would purchase the tookit. The cost of the toolkit verses your time in making the functions will pay off. However if your an acedemic assosicate whos university has subscribed to NI's Acedemic package then this is included as apart of the bundle.

Hope this helps.

Kind Regards

Steven Bird
Applications Engineer
National Instruments