I am wondering what are the Contraints.Reaction.Fout values. As I run my
model with and without muscles, I get different values for those. Therefore,
I conclude that these are not the Reaction Forces, as defined when doing
classical inverse dynamics (reaction forces and moments passed from one
joint to the other), since they should not change with or without muscles.
So my questions:

What are these Constraint.Reaction.Fout value?

How can I get those reaction forces that come directly from the
classic inverse dynamics analysis?

Thanks!

Jean-Olivier

[Non-text portions of this message have been removed]

I have noticed this also, and wonder why they would be different.

Brent

— In anyscript@yahoogroups.com, Jean-Olivier Racine
<jean-olivier.racine.1@…> wrote:
>
> Hello all,
>
>
>
> I am wondering what are the Contraints.Reaction.Fout values. As I run my
> model with and without muscles, I get different values for those. Therefore,
> I conclude that these are not the Reaction Forces, as defined when doing
> classical inverse dynamics (reaction forces and moments passed from one
> joint to the other), since they should not change with or without muscles.
> So my questions:
>
>
>
> 1. What are these Constraint.Reaction.Fout value?
> 2. How can I get those reaction forces that come directly from the
> classic inverse dynamics analysis?
>
>
>
> Thanks!
>
> Jean-Olivier
>
>
>
> [Non-text portions of this message have been removed]
>

Contraints.Reaction.Fout is a menber of any constraint. It is the
force(s) in the constraint. If the constraint is a joint then
Contraints.Reaction.Fout contains the joint reactions just as you
anticipate.

But here is the point of the story: Joint reactions are very
different depending on whether you have muscles in the model or not.
Joint reaction forces in models relying only on joint torques, i.e.
classical inverse dynamics, are hugely under estimated. If you only
have joint torque providers in the model, then the joint reactions
are only what the external forces produce. When you include the
muscles, their contribution to the joint reaction is added and it is
often larger than what the xternal forces provide. A muscle can only
produce torque in a force couple with a joint reaction, so the real
joint reactions are much larger than what you get from a model with
pure joint torques.

In other words, it is correct that you get different joint reactions
depending on whether you include muscles in the model or not.

Best regards,
John

— In anyscript@yahoogroups.com, Jean-Olivier Racine <jean-
olivier.racine.1@…> wrote:
>
> Hello all,
>
>
>
> I am wondering what are the Contraints.Reaction.Fout values. As I
run my
> model with and without muscles, I get different values for those.
Therefore,
> I conclude that these are not the Reaction Forces, as defined when
doing
> classical inverse dynamics (reaction forces and moments passed from
one
> joint to the other), since they should not change with or without
muscles.
> So my questions:
>
>
>
> 1. What are these Constraint.Reaction.Fout value?
> 2. How can I get those reaction forces that come directly from
the
> classic inverse dynamics analysis?
>
>
>
> Thanks!
>
> Jean-Olivier
>
>
>
> [Non-text portions of this message have been removed]
>

Contraints.Reaction.Fout is a menber of any constraint. It is the
force(s) in the constraint. If the constraint is a joint then
Contraints.Reaction.Fout contains the joint reactions just as you
anticipate.

But here is the point of the story: Joint reactions are very
different depending on whether you have muscles in the model or not.
Joint reaction forces in models relying only on joint torques, i.e.
classical inverse dynamics, are hugely under estimated. If you only
have joint torque providers in the model, then the joint reactions
are only what the external forces produce. When you include the
muscles, their contribution to the joint reaction is added and it is
often larger than what the xternal forces provide. A muscle can only
produce torque in a force couple with a joint reaction, so the real
joint reactions are much larger than what you get from a model with
pure joint torques.

In other words, it is correct that you get different joint reactions
depending on whether you include muscles in the model or not.

Best regards,
John

— In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com> ps.com,
Jean-Olivier Racine <jean-
olivier.racine.1@…> wrote:
>
> Hello all,
>
>
>
> I am wondering what are the Contraints.Reaction.Fout values. As I
run my
> model with and without muscles, I get different values for those.
Therefore,
> I conclude that these are not the Reaction Forces, as defined when
doing
> classical inverse dynamics (reaction forces and moments passed from
one
> joint to the other), since they should not change with or without
muscles.
> So my questions:
>
>
>
> 1. What are these Constraint.Reaction.Fout value?
> 2. How can I get those reaction forces that come directly from
the
> classic inverse dynamics analysis?
>
>
>
> Thanks!
>
> Jean-Olivier
>
>
>
> [Non-text portions of this message have been removed]
>

[Non-text portions of this message have been removed]