EMG to activation

[baoping xiong]

Does opensim have a function of converting the EMG signal into activation？If not, where can I find it?

[Dimitar Stanev]

Hi,

OpenSim does not convert EMG to activations, but the process is straightforward. Please see the previous posts for relative answers and suggestions.

viewtopicPhpbb.php?f=91&t=6952&p=18180&start=0&view=
search.php?keywords=convert+emg+&fid[0] ... 3fe7c71218

[baoping xiong]

emg = detrend(emg);
emg = ZeroLagButtFiltfilt((1/Fs), [30,300], 2, 'bp', emg );
emg = abs(emg);
emg = zeroLagButtFiltfilt((1/Fs), 6, 2, 'lp', emg);
I think all those is get excitation u(t) not the activation a(t),I understand is right?

[Dimitar Stanev]

The above algorithm approximates the envelope of your emg data. You would have to normalize this in order to be used as an excitation signal.

The activation can be considered a delayed version of the excitation. Nonetheless you can implement the first order dynamics (http://simtk-confluence.stanford.edu:80 ... n+Dynamics) apply the excitation and compute the activation manually.

[baoping xiong]

thank you