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system identification command line- impulseest
The "60" refers to the length of the FIR filter. An FIR model typically has larger number of coefficients than a rational transf...

12 years ago | 0

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Answered
system identification gui - fit to estimation data
When the amx3322 model was estimated, it was estimated to minimize the 1-step ahead prediction error. The fit value between the ...

12 years ago | 1

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How to design controller with control toolbox tools
You could try something along the lines of: m0 = idtf(ir, [1 zeros(1, length(ir)-1], 1/48000); m1 = balred(idss(m0), N); %...

12 years ago | 0

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What is the criterion of best fit in system identification toolbox?
Normalized Root Mean Square (NRMSE) criterion is used to generate the fit % number. It is a measure of how much better the model...

12 years ago | 3

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My model output is different with use of Simulink and sim function
For iddata source, it helps to set Tstart to 0 since the simulation in Simulink starts there by default. That is, use: XX = idda...

12 years ago | 0

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Answered
how to use the model which is done by System identification toolbox?
Did you set the initial conditions correctly? See: http://www.mathworks.com/matlabcentral/answers/72338-how-fix-the-problem-...

12 years ago | 0

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how to find parameters (A and B ) for a non linear arx model and how can i convert this non linear arx model into transfer function
"Converting" a nonlinear model into a linear one is an exercise in linearization. See idnlarx/linearize and idnlarx/linapp funct...

12 years ago | 0

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About the underlying principle of the function "predict"
The prediction is based on computing a kalman filter. See chapter 3 in "System Identification, Theory for the User", 2nd ed, Len...

12 years ago | 0

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Model generated by system identification tool when transported into simulink, does not match and is unstable
Hi Saurabh, Could you try running the SIM command in the MATLAB Command Window (e.g. y = sim(pss3, input)) and check if the sim...

12 years ago | 0

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Is there a way to output the final simulated time-response from procest()?
Ah, I see it now: it is the InputOffset that you estimated or supplied during process model estimation but perhaps did not speci...

12 years ago | 0

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Answered
Bode diagram of poor input/output signal
bode(sys,[w1 w2],'.'), where w1 and w2 are your two input frequencies and sys is the identified model.

12 years ago | 0

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Answered
Identification of MISO / MIMO models based on transfer functions: poles multiply contained in resulting model
The repeated poles are probably a result of concatenation; do pole(ss(zpk(rss(2,2,2)))) to check this phenomenon. You can use SM...

12 years ago | 0

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Is there a way to output the final simulated time-response from procest()?
Hi James, If the estimation focus is "simulation", you should not really see this difference. What MATLAB release are you seein...

12 years ago | 0

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How to fit data into nonlinear model
Is there an input/output relationship among the 2 variables? That is, does changing one affects the other in a cause-effect mann...

12 years ago | 0

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What are the 7 states for the model?
Can you elaborate on what you mean by "defining the states"? If you want to calculate the state-trajectory (as a function of tim...

12 years ago | 0

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What is the cost function in the optimization problem of the pem and greyest functions for multiple outputs?
The weighting matrix by default is inverse of noise variance which is simultaneously estimated along with the model parameters. ...

12 years ago | 0

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how fix the problem of the initial state
You have to make sure that in your new simulation environment the model uses the same input data (check any detrending) and init...

12 years ago | 0

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How can I correctly debug a dll project in System Identification Toolbox.
Compilation of estimation commands of System Identification Toolbox is not supported. You can compile only the deployment of the...

12 years ago | 0

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How to find out the options set for armax?
In "auto" search mode, the descent direction can change (among gn, grad, lm and gna) in every iteration. It is not like a fixed ...

12 years ago | 0

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How do you implement an ADL model in Matlab using ARMAX?
You have 2 inputs with minimum lag of 1 sample each. Also you have only one term of each variable. So set up ARMAX orders as: ...

12 years ago | 0

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How to find a system response of armax model for other data set? What e(t) in the system model?
Finding values of y(t) for a given u(t) is *simulation*. Use the SIM command: <http://www.mathworks.com/help/ident/ref/sim.html...

12 years ago | 0

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Errors occur during grey-box modeling
D matrix is 2-by-2 suggesting that the number of inputs (nu) = number of outputs (ny) = 2. However, C is 1-by-2 implying ny = 1....

12 years ago | 0

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Trouble with idgrey constructor in R2012b: Structure object modification slow
Hi Peter, Thanks for your inputs. It will indeed be nice to have some optimized functions that modify a models parameterizati...

12 years ago | 0

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How can I determinate the delay and the time constant from script?
Try impulse response estimation based approaches, assuming you are able to find a good FIR model for data (which you can ascerta...

13 years ago | 0

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how to disable the picture
It is the RESID command that is bringing up the plot. It belongs to System Identification Toolbox. To make it work as documented...

13 years ago | 1

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Failure while using function pem of system identification - plot compare shows step at the beginning of the signal trend
Difficult to say without looking at the data, but try using zero initial conditions for the comparison: compare(z_mittel,P1DI...

13 years ago | 0

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Answered
plotting state space models gives two different results
Not sure what your question is. But some notes: - COMPARE results are in general not reproducible by lsim unless you make sure ...

13 years ago | 0

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How can I get polynomials for MIMO case using iv4?
ARX does work for MIMO case. So does IV4. Can you post an example?

13 years ago | 0

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how to get the parameters of step response?
To elaborate on what Ryan wrote, suppose y is the vector of step response data and Ts is the sampling time. N = length(y); ...

13 years ago | 0

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fitting a transfer function from acquired data with tfest
What do you mean by "nominator"? N or D? Note that IDTF creates transfer functions that have a monic polynomial for the denomina...

13 years ago | 0