Simulation Mode

[TarunAgarwal]

Hello everyone

I want to Calculate the rise time and settling time for a second order control system

What can be the one way is to design Using the Control design and simulation module and then using control design and then going for CD paramaetric time response and all

I want to know if there is any other way around to this . I tried using simulation block and then control and simulation loop. and then created the transfer function.

Now i dont know how should i proceed.

[TarunAgarwal]

Please somebody help me with this how should i proceed...

[Barp]

Have you seen this post?

http://forums.ni.com/t5/LabVIEW/settling-time-rise-time-and-steady-state-error/m-p/2170818#M698532

It shows some 'shipping examples' with the module that could help you in how to calculate those parameters.

[TarunAgarwal]

I got it But its using control Design but what i want is using simulation (Using Control and simulation Loop) .Can u help me in this context.

[Barp]

Then you can use the internal VIs from this function:

This should provide the information you need. Now, notice also that you have to give the response of the system where you had reach the steady-state AND you also have to make your step response to start at zero.

Let me know if you have any more questions.

[Barp]

One more thing. The VIs from Control Design are not exposed on the palette. They are used internally to calculate values from a step response, but it should allow you to calculate the values from a simple simulation. Here is the location of the VIs.

C:\Program Files (x86)\National Instruments\LabVIEW 2012\vi.lib\addons\Control Design\_Dynamic Analysis\Dynamic Analysis.llb\Dynamic Analysis subVI\cd_Overshoot.vi

C:\Program Files (x86)\National Instruments\LabVIEW 2012\vi.lib\addons\Control Design\_Dynamic Analysis\Dynamic Analysis.llb\Dynamic Analysis subVI\cd_Settling time.vi

And if you have a older version of LabVIEW or your system is not 64-bit, you should be able to find those VIs by just opening the "CD Parametric Time Response.vi" and copy the VIs inside.

[TarunAgarwal]

I was able to calculate settling time but how to calculate rise time and steady state error.

 I try to convert the simulation module tf into control design tf but when i gave this as an i/p to CD Parametric Time Response.vi its not showing the value.

[Barp]

What you did your code is Incorrect. The "Convert SIM SISO Function to TF" converts models in Simulation into Control Design. You are feeding a waveform and the wire did not break because it is similar datatype, but they are different functions.

If you want to do that transformation, you need to use the System Identification Toolkit. It will convert the [X,Y] into a model.

Now, the easiest way to get the steady-state error, you can just get the 'final value' or the 'value at steady-state' and just make (1-steady-state)*100%. This should provide you with the information you need.

Again, as I said you have to allow the simulation to go until you reach steady-state. Right now, you are stopping the simulation before it reaches steady-state. To do that, you just need to increase the final simulation time.

[VASCO-1]

Hi Barp,

I have made a step forward on this topic - in my case I will surely have the transfer function model - but as You know - in the real life applications this is not a case.

My questions are following:

1. Question:  Why do we need the array size for the limit - and why is this 30 (see also graphs on the front panel  ) ?!
2. Question:  Is the proposed conversion OK ?!
3. Question: if the conversion OK - then the timereposne parametric data should be the same as for the CD Analysis : Overshoot ?!

Here are also figures as well as file.

Best regards Vasco