Hi all
I have done a model using ansys of a fgm plate with two piezoelectric layer in the top and the bottom of it. I get the reponse of the plate when I exited with 100v, now I need to get the space state model of the structures (plate+piezo layer) using system identification can any one help me with that
Your question is a bit vague. Do you have a mass-spring-damper system? Normally you get a 2nd-order vector differential equation of the system, where the mass, spring, and damping coefficients appear as matrices. You need to transform this into state space form (a standard procedure), where your system matrices are (A, B, C, D). Then perform a system identification to get the parameter matrices. However, your data is discrete and the model is continuous. You can do discrete identification, followed by d2c transformation, or you could use CONTSID toolbox to get a continuous time model directly. Note that there are issues with both of these (i.e., ZOH could be a problem). See enclosed thesis I obtained from the internet. It talks about what you want to do. However, I'm assuming you have a physical model in mind.
You can try to develop an mathematical model model like ARMA ,ARMAX, NARX etc to be used for system identification. Then the model parameters or coefficients can be designed in state space with the help of state equation and measurement equation. Then think about number of state variables needed to represent the model in state space form.
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