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Ligament Models
Posted: Tue Aug 18, 2009 8:35 am
by ambaus
Hello Forum,
Does anybody have a plugin for ligaments?
Thanks,
Anne
RE: Ligament Models
Posted: Sat Aug 29, 2009 8:50 am
by bunker
Did you received any answer ?
I think you can model a ligament using muscle editor and having specific parameters to simulate a ligament.
Anybody have added ligament to a model ?
Would be very helpful.
Thank you
Andrea
RE: Ligament Models
Posted: Mon Aug 31, 2009 10:25 am
by ambaus
Ajay Seth, a member of the OpenSim team, has a plugin for this. I think it is a modified muscle that doesn't have activation dynamics.
RE: Ligament Models
Posted: Mon Aug 31, 2009 1:17 pm
by aymanh
Anne,
I went ahead and posted some version of the source of our ligament plugin on the Wiki page at:
http://wiki.simtk.org/opensim/SamplePlugins
You can give it a try.
Note that you need to make/change your model to use <Ligament> in-addition-to/in-place-of some of your regular muscle (e.g. <Thelen2003Muscle>) for this to have any effect.
Best,
-Ayman
RE: Ligament Models
Posted: Mon Sep 21, 2009 5:34 am
by twdorn
Hi all,
I went ahead and inserted a ligament into my model using the Ligament plugin. However everytime I try and use CMC, it always fails when trying to find initial conditions. When removing the ligament, CMC works fine. I am not sure if this could be a bug or if anyone has tried this before and has a way around it...
The error is below:
=============================================
rdCMC.computeInitialStates: ti=0.15
=============================================
rdCMC.computeControls: t = 0.15
WARN- small force range for my_lig_r (-0.145283 to -0.145283)
WARN- small force range for my_lig_l (-0.000873351 to -0.000873351)
SimTK Exception thrown at CFSQPOptimizer.cpp:225:
Optimizer failed: CFSQP failed with status = 1
OPTIMIZATION FAILED...
rdCMC.computeControls: WARN- The optimizer could not find a solution at time = 0.150000.
If using the fast target, try using the slow target.
Starting at a slightly different initial time may also help.
RE: Ligament Models
Posted: Mon Dec 07, 2009 12:46 pm
by erkang
Tim,
Did you get the problem associated with CMC and ligament solved.
Thanks,
Kang