how to fit a Nonlinear model with multiple input and single output by using dataset in matlab

4 views (last 30 days)
i have input and output measured data for my system and i have ODE model equations which is bilinear and it has 11 states.
i want to fit the model with the measured data and i have to estimate the parmeters of that model, can anyone kindly help me to solve this problem. Thanks in advance.

Answers (1)

Thiago Henrique Gomes Lobato
Without your data nor any code is difficult to specifically help you. Still, a general thing you may do, if you already have the model, is to simply optimize the parameters. An way to do it is:
Par0 = InitialParameters;
[Par,fval] = fminsearch(@(Par)Error(Par,Input,Output),Par0)
function e = Error(Par,Input,Output)
ModelOuput = YourModel(Par,Input);
e = rms(ModelOutput-Output);
end
Just substitute the variables/functions accordingly.
  2 Comments
Padmapritha T
Padmapritha T on 19 Apr 2020
Thank you for your reply sir,
i did this by the following code in matlab.
but the FPE was very high, is there any possibility to reduce the FPE.
data = iddata(Glu,input,Ts);
data.Tstart = 0;
data.TimeUnit = 's';
nx = 11;
in_sys = n4sid(data,nx,'Ts',900);
sys = pem(data,in_sys);
copmare(data, sys);
where Glu is my measured output data and my system has 2 inputs.

Sign in to comment.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!