emg data

[dana damian]

Hi,

for those with experience, do you see some solution by which OpenSim can be used to generate signals like EMG signals?
I can see there are some files which are likely to record muscle excitation through the CMC tool, but it's probably because i'm a newbie that i can't yet figure out how to exploit them to model some data like EMG.

Thanks!
D.

[Daniel Leib]

Howdy,

When you run a forward dynamics simulation, the file "*_states_controls.sto" (as named in the demo, you can name it whatever you like in other simulations) holds the muscle activation data for the simulation. You can either plot it by opening the plot tool -> y-quantity -> load file ->"...\resultsforward\filename" or open the .sto file up in Excel or similar program as a tab delimited document.

I've looked at the data in the walking demo and a cycling simulation; timing looks pretty reasonable, though I can't vouch for magnitude as I haven't incorporated forces into cycling yet.

[dana damian]

Thanks for the reply, Dan.
I followed what you were saying and it worked. But applying this(and not only) for a longer while than the default takes a lot of time for computation behind!
I figure out that it takes so much time also due to the fact that graphics frames are updates after each computation. But isn't there a way to skip the interface, and just let the computation go, so that it finishes faster?

Thanks, again!
Dana

[Daniel Leib]

Hi Dana,

Glad it worked, but I'm not sure about disabling the graphics display. One note on computation speed, however. The program can only take advantage of one processor core while computing things, so a higher frequency single or dual core processor will go faster than a lower clocked quad core or dual core. Hopefully Dr. Habib can chime in on the graphics display!

[Daniel Leib]

*edit - easier than I thought, just close the view pane by clicking the 'x' next to the view tab in the upper left.

Have a good one,

Dan

[Ayman Habib]

Dan,

Confirmed, though I have to say that the contribution of the display overhead is minmal probably except during "forward".

You can also run the tools using command line version without even having to open the GUI. The GUI saves you creating the "setup" files by hand but you can
- Do the configuration in the GUI.
- Save settings from the bottom panel of the tool to a file.
- Run the tool from command line using
"> Toolname -S nameOfTheFileYouSaved"
where toolname is one of {scale, ik, cmc, forward}.
You need to make sure to save the file in the proper directory (same as model) since some path names in the file may not be absolute.

-Ayman