MATLAB: Best way to resample the output of a Simulink simulation with variable time step into a signal with a fixed sample time

resampletime series

I have a simulation model that runs with a variable timestep:

(I don't want to change this)

For the purpose of system identification it would be convenient to have the output signals sampled at a regular frequency.

This seems to work:

y_resampled = resample(simOut.POW,simOut.POW.Time)

According to the documentation, this resamples the values, simOut.POW, by linear interpolation onto a vector of uniformly spaced instants with the same endpoints and number of samples as simOut.POW.Time.

Not sure if it is the right way to do it or if there is a better function to use.

Best Answer

No, resample() samples the signal at vector specified by simOut.POW.Time. So, in this case, it is not doing anything. I suggest using interp1()

t_equally_spaces = min(simOut.POW.Time):0.01:max(simOut.POW.Time);
y_resamples = interp1(simOut.POW.Time, simOut.POW.Data, t_equally_spaces)

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Sample Time Offset:

http://blogs.mathworks.com/seth/2011/11/20/sample-time-offset/

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Comments

The letter "A" as the name of the variable, which holds the force data, is a poor choice.
There is half a second more acceleration data than force data.
interp1() is older than resample().
to use resample() requires more reading of the documentation

To use interp1() (or resample()) time data is needed.

Try this script to see if it does what you want.

%%


A = load('Acceleration_Data.mat');
F = load('Force_Data.mat');
%%
A.time = linspace( 0, numel(A.B)/2222, numel(A.B) );
F.time = linspace( 0, numel(F.A)/2000, numel(F.A) );
%%
F.resample = interp1( F.time, F.A, A.time, 'linear', nan );

"I guess that the best method is to resample the acceleration data at 2222 Hz ?" I'm not sure what this means.

Do you want to resample acceleration?

A.resample = interp1( A.time, A.B, F.time, 'linear', nan );

Best Answer

Related Solutions

MATLAB: The art of delaying (discrete)

MATLAB: Resampling two signals to the same frequency

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