Inverse dynamics

[Suresh Chinthakunta]

Hi,

My group and I are working on a musculoskeletal model of the spine in opensim. We are all fairly beginner here and have been running through the tutorials, looking at the confluence web-site etc.

We have a generalized model developed from the literature, and as a result we do not have external load data, such as force plates, etc.

In fact the model does not go to the feet, but stops at the pelvis.

We are attempting to solve an inverse dynamics problem and determing the internal loads/torques at the joints of the spine. We are able to do so, but have left "unchecked" the external load tab, because we do not have external loads.

Is our output of internal forces/torques just junk because we do not have applied forces? Without applied forces how is it even able to solve at all? The only thing I can think of, is that gravity is incorporated through the center of mass and is the applied force.

Any help is appreciated.

Thanks

[Ayman Habib]

Hi Suresh,

Yes indeed, gravity is on by default and would be the only force acting on your model (unless you have forces other than muscles in your model). You might find it useful to check the spine model here as well.

https://simtk.org/project/xml/downloads ... oup_id=567

Best regards,
-Ayman

[Brandon Bucklen]

Thanks Ayman,

That is the spine model we were referring to. We did not see any reaction or ground forces that came with that model.

Thanks,

Brandon

[Filippo Soremic]

Hi, I'm Filippo, a student from University of Pisa.
For my master Thesis I'm studing the load on the spine during lifting.
The study is on firefighter tasks.
I'm trying to use some OpenSim model, lumbar spine and arm26, but I can not add external force...how can I do?

Every help is golden!!!

Thanks to all users,
Filippo