MATLAB: Transfer function from measured input signal and output signal

controlinputmathematicsMATLABmultipleoutputsignalsignal processingsimulinktransfer function

Dear Matlab and Simulink user,

Is there any way with parameter estimation toolbox or any another method to generate transfer function from multiple inputs and multiple outputs Signals?

Best Answer

The sampling interval ‘Ts’ is enough. Note that all your data must be sampled all with the same sampling interval. If they are not, you need to interpolate them to the same sampling interval with the resample function first.

I usually calculate the sampling interval as:

Ts = mean(diff(time));

For iddata, the output signal ‘data2’ is ‘y’, the input signal ‘data1’ is ‘u’, and ‘Ts’ is as I described it.

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Another approach:

data = iddata(rand(1,10)', (0:9)', 0.1);                % Create ‘iddata’ Object
y = data.OutputData;                                    % Get ‘OutputData’ As Double Array
ycs = cellstr(num2str(y));                              % Convert To Cell Array Of Strings

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I would use this syntax (from the documentation):

data = iddata(y,u,Ts) creates an iddata object containing a time-domain output signal y and input signal u, respectively. Ts specifies the sample time of the experimental data.

Specifically with respect to your data, I would do something like this:

time = data(:,1);
Ts = mean(diff(time));
time_data = iddata(data(:,2),data(:,3),Ts);
freq_data = fft(time_data);
freq_units = freq_data.units;
Fr = freq_data.frequency;
sys = tfest(freq_data,2)

NOTE — I do not have your data so this is UNTESTED CODE. I cannot be certain it will work without modification.

Best Answer

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