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Date:
2012-11-30 20:49
Priority:
3
State:
Open
Submitted by:
Nobody
Assigned to:
Matthew Millard (mjhmilla)
Summary:
Incorrect default muscle force-length curve used for Schutte1993 model

Detailed description
I've found that when I define a Schutte1993 muscle, but don't specify the passive force length curve, tendon force length curve, or active force length curve in the definition of the specific muscle, but instead define these parameters in the "default" muscle section, I get incorrect values for the passive force generated by the muscle. My test case is a gravity driven simulation of the upper arm with a single muscle and no activation. If I copy the force length parameters from the default section to the defined muscle, the correct force is reported in the plotting tool.

Interestingly, this difference doesn't appear to change the arm trajectory in the gravity driven simulation, therefore, it may just be an issue with the method the plotting tool uses to compute the muscle force from a motion derived from the forward dynamics simulation. Attached is a plot of passive muscle force vs. time for a simulation with the parameters specified just in the default section (red) and defined in both the specific muscle and default sections (green).

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Message  ↓
Date: 2013-01-11 17:06
Sender: Ayman Habib

The bug report doesn't have a user to get more info, but I'm leaving the bug open and assigning to Matt as I don't know the expected behavior especially that Schutte muscle model is deprecated. Matt, please close if you see fit and that the reported issue does not come up with the new muscle models. Thanks,
-Ayman

Attachments:
Size Name Date By Download
32 KiBplot.JPG2012-11-30 20:49Noneplot.JPG
Field Old Value Date By
assigned_tonone2013-01-11 17:06aymanh
File Added488: plot.JPG2012-11-30 20:49None
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