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transfer function + controller + Bode plot and root locus

I am trying to plot Bode plot and root locus for trasfer function
TF = 1/(s^4 + 2s^2)
Then I want to implement Ideal compensators (PI , PD or PID) or lag/lead compensator to get the required stability
I am trying to do this Labview 8.o in control design and simulation loop. (V2.0)
I have done some simulation but I am not understanding as to how implement controller on this.
I need little help.
I am attaching my VI. but you will find rootlocus not there and feed back loop control to implement controllers not there
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Message 1 of 5

      I am a little confused as to what you are asking.  You asked for "how to implement controller on this" Are you trying to run this VI on a Fieldpoint Controller? Also, it doesn't look like your VI got attached when you posted.  If you could provide more information as to what you are trying to do and what the problem is I might be able to help. 


John H
Applications Engineer
National Instruments
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I have one typical controlers question where I am using feedback control
alongwith compensators. My transfer function is like fourth order
TF = 1/S^2(S^2+2)
but  rootlocus and transfer function in labview  do not let me write equation more than 3rd order.
How can I write this 4th order equation.
Next I want to make one feedback control on this transfer function and then want to plot bode and rootlocus.
I have made one vi of fourth order by placing transfer function in series and then for feedback gain I have placed another transfer function with feedback. I have also attached rootlocus vi but it does not show me rootlocus since rootlocus Vi can not take more than fourth order transfer function.
I want to plot my step response, bode, and root locus for step input
I have also tried to  make another VI with tansfer function VI which has feed back terminal in it, but I donot know how to get bode and rootlocus out of that.
I am attaching my both VIs for you.
see my two Vis please.
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Message 3 of 5

      I just wanted to let you know that I am looking into this but have not really figured anything out.  I'll post here as soon as I know something.  Thanks.

-John H
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Message 4 of 5


maybe this vi can help you with implementation of a unity feedback loop with a controller and your plant on the forward loop.


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