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Problem with ident GUI while predicting time-series
When predicting, the results depend upon the initial conditions. The GUI estimates the initial conditions to maximize the fit to...

plus de 12 ans il y a | 0

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Prediction confidence intervals using a state-space model
For discrete-time systems, the forecasting model is same as the simulation (original) model. So you can use commands such as SIM...

plus de 12 ans il y a | 1

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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...

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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 ...

plus de 12 ans il y a | 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); %...

plus de 12 ans il y a | 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...

plus de 12 ans il y a | 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...

plus de 12 ans il y a | 0

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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-...

plus de 12 ans il y a | 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...

plus de 12 ans il y a | 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...

plus de 12 ans il y a | 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...

plus de 12 ans il y a | 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...

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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.

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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...

plus de 12 ans il y a | 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...

plus de 12 ans il y a | 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...

plus de 12 ans il y a | 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...

plus de 12 ans il y a | 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. ...

plus de 12 ans il y a | 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...

plus de 12 ans il y a | 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...

plus de 12 ans il y a | 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 ...

plus de 12 ans il y a | 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: ...

plus de 12 ans il y a | 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...

plus de 12 ans il y a | 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....

plus de 12 ans il y a | 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...

plus de 12 ans il y a | 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...

presque 13 ans il y a | 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...

presque 13 ans il y a | 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...

environ 13 ans il y a | 0

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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 ...

environ 13 ans il y a | 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?

environ 13 ans il y a | 0