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How to use the EMG Raw Data in Myo Armband

I'm working on a project to try to recognize some movements/poses for use in rehabilitation therapy using Myo Gesture Control Armband.

I have three questions:

  1. Which is the maximum and minimum value that EMG Raw Data returns?

  2. How do you interpret the EMG Raw Data?

  3. The minimum value returned by the EMG Raw Data is for a relaxed muscle and the maximum value is a fully contracted muscle?

PS1: Question in Myo Developer Forum

PS2.: The most important to me is learn how interpret the EMG Raw Data. With some didactic sample. I want to create my own gestures.

Solution

  • This is from my looking results and understanding:

    1. EMG Raw Data return value from -128 to 127 (8-bit value).
    2. We don't really know what is EMG Raw Data. We can't say it's mV directly from muscles intensity. Sensors measure mV and convert to 8-bit data.
    3. This is signal. Around 0 is "relaxed muscle" not minimum. But converting from mV to 8-bit data can make strange values too. Soo 2. and 3. question I can't really answer how it's work, because Myo don't show own hardware for converting values (or I don't find that). I recommend visit Myo diagnostic page and see what happend in EMG graphs while you relaxed and contracted muscle.