data to transfer function (idfrd) error

Question

sangwoo ha 2021-7-2

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/870268-data-to-transfer-function-idfrd-error

评论： sangwoo ha 2021-7-2

data = importdata ('C:\Users\sangwoo\Desktop\mash_change_500Hz_tf.mat');
freq = 1:1:500;   % frequency range
w = freq*2*pi; %angle freq
frf = data;   % FRF complex number 
Fs = 500*2*32;
Ts = 1/Fs;
np = 10; %number of poles
nz = 10; %number of zeros
%% 1 iddata 
gfr = idfrd(frf,w,Ts) 
%% 2 system 
sys = tfest(gfr,np,nz)
%% 3 num, den 
num = sys.Numerator;
den = sys.Denominator;
% 
% %% 4 continuous transfer function
% 
G = tf([num],[den]);
figure(1)
bode(G)
figure(2)
semilogx(2*pi*freq,20*log10(abs(frf))) %compare 

left is plot from data right is plot of G ; rad/s and magnitude at resonance is not matched

at tfest process, matlab tell accuracy is 99.7 percent. so i think gfr = tfest. but at idfrd process, some bad think happened. please give me some help to make accurate model