when i run frestimate(mdl,io,in) , it comes out following warnings, what can i do~

??? Error using ==> frestimate>LocalCheckDataTypeAndSampleTime at 532
In "frestimate(modelname,op,io,in)", the input signal "in" is a
frest.Sinestream signal which has parameter values for "Frequency" and
"SamplesPerPeriod" such that it inherently has multiple sample times.
Using such an input signal requires that samples rates belonging to the
Simulink signals where your linearization input and output points are
located are either continuous or fixed in minor time step and the
linearization I/O io(1) does not satisfy this requirement. Consider either
changing the sample time of Simulink signal where io(1) is located to
continuous sample time or using frest.createFixedTsSinestream utility to
create a sinestream signal that has a single sample rate.

Error in ==> frestimate>LocalSetupForSimulation at 379
isVarTs = LocalCheckDataTypeAndSampleTime(table,in,ModelParameterMgr);

Error in ==> frestimate at 94
[parammgr,SimulationPackage] =
LocalSetupForSimulation(model,io,op,in,numout,opts);

Answer 1

[Arnaud Miege]

The error message suggests two things, have you tried them?

1. Change the sample time of the Simulink signal where io(1) is located to a continuous sample time
2. Use frest.createFixedTsSinestream to create a sinestream signal that has a single sample rate

Without seeing the model and the code, it's difficult to be more specific.

HTH,

Arnaud

[James Zhao]

hello,Arnaud Miege,i tried using 'frest.createFixedTsSinestream',and it came out following warning.and i have no idea how to "Change the sample time of the Simulink signal where io(1) is located to a continuous sample time

", please help me out

"??? Error using ==> frestimate>LocalCheckDataTypeAndSampleTime at 538

In "frestimate(modelname,op,io,in)", it is required for each of the linearization input I/O

points that the sample time of the Simulink signal where it is located is one of the following:

1. It is either continuous or fixed in minor time step.

2. Its sample rate is equal to the sample rate of the input signal "in".

The linearization I/O io(1) does not satisfy this requirement. Consider either changing the

sample time of Simulink signal where io(1) is located to continuous sample time or changing the

sample time of input signal "in".

Error in ==> frestimate>LocalSetupForSimulation at 379

isVarTs = LocalCheckDataTypeAndSampleTime(table,in,ModelParameterMgr);

Error in ==> frestimate at 94

[parammgr,SimulationPackage] = LocalSetupForSimulation(model,io,op,in,numout,opts);"

[James Zhao]

and i upload my mdl, hope you can see it~

http://www.megaupload.com/?d=XSUK152P

[Arnaud Miege]

I can see the model, but I don't know what code you're using to estimate the frequency response. Could you post this as well?

With regards to your other points, maybe you should familiarize yourself with Simulink before attempting advanced manoeuvres like frequency response estimation. Have a look at the Simulink tutorials on the MathWorks website (http://www.mathworks.co.uk/academia/student_center/tutorials/simulink-launchpad.html) and also Working with Sample Times in the Simulink documentation (http://www.mathworks.com/help/releases/R2011a/toolbox/simulink/ug/br09i6c.html).

[James Zhao]

Thank you for your advice, i'm working on it,i use following codes:

>mdl='anynch'

>io=getlinio(mdl)

>linsys=linearize(mdl,io)

>in=frest.Sinestream('Frequency',logspace(-1,1,50),'Amplitude',1e-3)// or >in=frest.createFixedTsSinestream (5e-6)

>sys=frestimate(mdl,io,in)

before i type in such codes, i've already set 'input''output''openloop' in pid controller model.

[Arnaud Miege]

Can you explain about the I/O points? Do you mean the inputs and outputs of the PID controller? Why openloop? What are you trying to get the frequency response of? Shouldn't the I/O points be at the top-level of the model, e.g. w* and w? Also, are you aware that you are using a discrete sample time of 1s for your PID controller, whereas your electrical model has been discretized with a sample time of 1e-5s? Is that really what you intend to do?

Answer 2

[SimTec]

Dear Miege, How can we Change the sample time of the Simulink signal where io(1) is located to a continuous sample time, I right-click on the io and I could not see any parameter related to sample time best regards

[Abdullah Al Masud]

Hello Zhao,

I am also having the same problem. Have you found any solution yet?

[MULTAN007]

Hi,

James Zhao, TarikTech and Abdullah Al Masud, did you get the solution for this issue? I'm having same sitation. Thanks in advance for your response and time.