EMG during Walking : On/Off detection
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Marie-Caroline
le 9 Fév 2024
Réponse apportée : Alex Wu
le 25 Mar 2024
I would like to define an accurate threshold to detect ON/OFF bursts.
Please find attached my EMG signal (rectified).
I am able to code when the muscle activity exceeds the double or triple SD rang (i.e. the muscle is defined to be
“On” or activated).
Threshold=std(A(1:800,1)).*(2.5)
if A>Threshold
DataON=A>Threshold
DataONOFF=diff(DataON)
BUT : Because single spontaneous spikes can easily exceed the SD range, I need to define
a minimum time (minimum subperiod duration) that the EMG signal has to constantly stay OVER the threshold
to be accepted as “On” (e.g. 50 ms). So I would like to translate something like that :
if A>Threshold (and data over threshold during 50 ms)
2 commentaires
Star Strider
le 9 Fév 2024
The 'Threshold' value is really low — about 17.5 — with the peaks in the range of 100 to 2000. Also, the sampling frequency is missing, so it’s not possible to determine the activation duration. I would use a differerent approach to this, however I first need to understand what exactly you want to do.
It would also help to know what release you’re using, and if you have the Signal Processing Toolbox.
Réponse acceptée
Alex Wu
le 25 Mar 2024
Hi Marie-Caroline
Please check this example Label High-Amplitude Regions in EMG Signal, where we use sigrangebinmask function to label regions where the EMG amplitude is greater than 0.25 (threshold) for at least 0.5 seconds (minimum subperiod duration).
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