Bump ---> Identification using invfreqs

Hello all,

I want to fit a model to the data peaks at around 70 Hz and 183 Hz. But for some reason can never fit the peak at 70 Hz.

tol = 1e-7;

frd = 2*pi*F; %frequency in rad/s

[numG,denG] = invfreqs(Txy,frd,15,17,[],1000,tol);

sys = tf(numG,denG);

figure; hold on; semilogx(frd,magdbTxy,'b');

bode(sys,frd,'r'); hold off;

Is there a way to specify which peaks I want to fit a model to?

Thanks a lot.

Answer 1

[Rajiv Singh]

Have you tried using the weight input argument? You can specify higher weights for the frequencies around which you are interested in capturing the response.

See also: tfest and accompanying option set tfestOptions (option called "Focus" in particular). These functions belong to System Identification Toolbox.

[Sheikh]

Thanks Rajiv. I will try that and let you know how it goes.