Synergy Implementation in NCP Model

Neuromusculoskeletal Modeling Pipeline is a series of modules to 1. create a highly personalized OpenSim model of an individual patient and 2. simulate potential surgical changes and their resulting outcomes.

At this time the NMSM Pipeline is still in
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Ananya Sundararajan
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Joined: Tue Sep 19, 2023 6:11 am

Synergy Implementation in NCP Model

Post by Ananya Sundararajan » Wed Feb 28, 2024 10:38 am

Hi,

I am interested in understanding how synergies are represented in the model. I was trying to look into where the synergy commands and synergy vectors are located in the code.

When defining the RCNL Synergy Set in the NCP Settings File, a number of synergies per muscle group is specified. Are these the number of synergy commands?

Additionally, I was looking into the synergy weights output file, and was assuming that this would be the synergy vectors. However, it seems like the synergy weights are time dependent, as there seems to be 12 time steps in the file. Is there a different file that contains the synergy vectors per synergy command? If so, what do the synergy weights specify?

I was also wondering if there was a recording reference for the 2023 Grand Stroke Competition powerpoint presentation.

Thank you for your help,
Ananya Sundararajan
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Kayla Pariser
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Joined: Mon Jul 30, 2018 10:35 am

Re: Synergy Implementation in NCP Model

Post by Kayla Pariser » Tue Mar 05, 2024 2:40 pm

Hi Ananya,
Thank you for expressing interest in the NMSM Pipeline and NCP! For starters I want to let you know that we have v1.1 coming out very soon. In v1.1 all of the model personalization and treatment optimization tools are updated for more functionality and we will also include improved examples and tutorials. Specifically we plan to add an example of how to use the synergy commands and vectors to reconstruct the muscle activations. Please be on the lookout for that and make sure you are on the mailing list for this SimTK page so you get the notification when v1.1 of the NMSM Pipeline is officially released! Now to answer your questions:
When defining the RCNL Synergy Set in the NCP Settings File, a number of synergies per muscle group is specified. Are these the number of synergy commands?
Yes! These are the 12 synergies, where we have 6 defined per leg.
Additionally, I was looking into the synergy weights output file, and was assuming that this would be the synergy vectors. However, it seems like the synergy weights are time dependent, as there seems to be 12 time steps in the file. Is there a different file that contains the synergy vectors per synergy command? If so, what do the synergy weights specify?
We are trying to keep the output files in formats that work with OpenSim. To keep the output files from NCP as .sto files that are compatible with OpenSim we have to keep that first column labeled "time". However, you correctly noted that these numbers are not time. The time column is instead the synergies (e.g. 1 = synergy 1) as defined in the RCNL Synergy Set in the NCP Settings File. We understand this is confusing and will try to see what we can do to add in the header of the file that the time column is actually the synergy set.
I was also wondering if there was a recording reference for the 2023 Grand Stroke Competition powerpoint presentation.
We do not have a recording of the powerpoint presentation. Do you have specific questions about the content in the presentation about either the NMSM Pipeline or the Stroke Grand Challenge competition? I am happy to answer any questions you have either via this forum or email (nmsm@rice.edu).

I hope this helps!

Kayla
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