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Rajiv Singh

MathWorks

Last seen: etwa ein Monat ago Active since 2011

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Answered
LOES of a high order state space model
You could attempt this in frequency domain. G = frd(OriginalModel,w) % w is a suitably chosen frequency grid ReducedModel = ss...

etwa ein Jahr ago | 1

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Answered
How to build a single input multiple output ARX or ARMAX model with MATLAB
Identification routines want variables to be arranged along the columns, time along rows. Your data "y" is transposed. Also, the...

etwa ein Jahr ago | 0

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Answered
Use of modalfrf for operating measurements
This is essentially a system identification problem. You have non-parametric (tfestimate, spa, spafdr, etfe) techniques and para...

etwa ein Jahr ago | 0

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Answered
How to remove delay from idtf object?
You will need an invertible realization. Try high order transfer function estimations with no delays. Or, if the estimated model...

etwa ein Jahr ago | 0

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Answered
Testing different optimization methods on a state space model by solving ODEs
The closest infrastructure to this style of numerical optimization approach is "grey box identification". See idgrey, idnlgrey, ...

etwa ein Jahr ago | 0

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Answered
nlarx model initial conditions
You can prefix estimation data (both input and output signals) with nd zeros, where nd = maximum lag in the model. Initial condi...

etwa ein Jahr ago | 0

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Answered
How to force tfest to estimate the process with "only real poles" ?
TFEST cannot guarantee real poles. If you can work with <=3 poles and <=1 zero, try PROCEST. This is a process model estimator...

etwa ein Jahr ago | 3

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Answered
What is the difference between FRD and IDFRD
Both FRD and IDFRD are used to store Freqyency Response Data, that is, the complex frequency response vector (Mag.*exp(i*Phase))...

etwa ein Jahr ago | 1

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Answered
How to estimate the parameter in a customized transfer function
Grey-box identification is an option. You will need to write a function that takes K0 and a0 as inputs, and returns state-space ...

etwa ein Jahr ago | 0

Answered
Minimum input data resolution
Look up Nyquist Sampling Theorem. If you are sampling (hopefully with anti-aliasing) at 1Hz then you cannot theoretically captur...

etwa ein Jahr ago | 0

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Answered
Well-identified fitted process model does not behave like data on simulink
You are almost there. Convert the model into state-space form and use it for simulation. For initial conditions, you will need t...

etwa ein Jahr ago | 0

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Answered
How to calculate the transfer function for a 16 input system?
Try also TFEST. Although you might want to reduce the number of inputs by PCA or PLS analysis.

mehr als ein Jahr ago | 0

Answered
nlarx model compare and predict (horizon kept 1) fit totally differs
The difference between (finite-horizon) prediction and simulation is a fundamental concept, something you could read books/artic...

mehr als ein Jahr ago | 0

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Answered
Can nlgreyest() estimate open-loop unstable models?
With greyest, either parameterize K matrix using the ODE function, or choose to esitmate it separately by using the "Disturbance...

mehr als ein Jahr ago | 0

Answered
System Identification of Closed Loop Data and Unstable Plant
The first reference: [1] System Identification — Theory For the User, Lennart Ljung, Section 13.4-13.5, 2nd ed, PTR Prentice Ha...

mehr als ein Jahr ago | 0

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Answered
Accessing the GUI function programatically.
I will repeat Aditya Baru's comment as an answer. The App now supports MATLAB code generation (creating a function from the tas...

mehr als ein Jahr ago | 1

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Answered
How to set parameters of Recursive Polynomial Model Estimator in Simulink
The Recursive Polynomial Model Estimator supports single output estimations only.

mehr als ein Jahr ago | 0

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Answered
System Identification - Frequency Domain
Make an attempt with stability enforced. opt = tfestOptions('EnforceStability', true); model=tfest(f_data,6,opt) Also, you ...

mehr als ein Jahr ago | 2

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Answered
System Identification Toolboox error dialog
What dataset are you using for validation? Does it suply the inputs and outputs that the model needs?

mehr als ein Jahr ago | 0

Answered
Does the order (index) of inputs and outputs matter in MIMO system identification?
Yes the order matters since within a given noise level, there are many models that can explain the data. Settings related to sea...

mehr als ein Jahr ago | 0

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Answered
System Identification Toolbox: How can we modify the starting parameters for the armax-algorithm?
You can set the A, B, C values explicitly, as in estimatedPolymodel.A = ARCoeff Or, call the IDPOLY constructor with A, B, C p...

mehr als ein Jahr ago | 0

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Answered
How to identify a sytem by the System Identification Toolbox that is invertable ?
Tyically yes. If you are estimating state-space model, use "feedthough" name-value pair, as in ssest(Data, order, 'Feedthrough'...

mehr als ein Jahr ago | 0

Answered
how to convert a xls to a data ensemble for import into diagnostic feature app
If the data is not too big to fit into MATLAB memory, I would suggest importing it into MATLAB first as a set of tables or timet...

mehr als ein Jahr ago | 0

Answered
How can I find initial states for simulation?
Initial states show the effect of the environment on the system. They are not a property of the system to be determined uniquely...

mehr als ein Jahr ago | 1

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Answered
System Identification toolbox: how to print estimated ARMA-coefficients for each iteration step in armax-algorithm
Use "full" display option, as in: opt=armaxOptions('Display','full'); estimatedPolymodel=armax(iddata(outputdata,inputdata,tsa...

mehr als ein Jahr ago | 1

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Answered
how to use state space model?
If you want to reproduce the response of "predict" by (manual) simulation, you will need to generate the right prediction model ...

mehr als ein Jahr ago | 1

Answered
how to plot on the same bode plot a manual function plot() with function bode()?
You could try: G = frd(f1(w),w); % assuming f1(w) is a complex numeric vector bode(G,f2)

mehr als ein Jahr ago | 0

Answered
Residual analysis of 100% fit model using system identification toolbox
With simulated data with no noise, it is difficult to read the residual results since there is no baseline noise floor. That is,...

mehr als ein Jahr ago | 0

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Answered
Fitting complex function to measurement values
Let X be your data matrix. [~,I]=unique(X(:,1),'stable'); h=X(I,2).*exp(1i*X(I,3)/180*pi); w=X(I,1)*2*pi; G=idfrd(h,w,'Ts',0...

mehr als ein Jahr ago | 0

Answered
MISO system identification tool box step response
Yes, use LSIM with input: U = [u, u], where u is a step signal.

mehr als ein Jahr ago | 0

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