EMG during Walking : On/Off detection
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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 Commenti
Star Strider
il 9 Feb 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.
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Alex Wu
il 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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