The rows are each corresponding to one degree of freedom. In principle, you
do not know any more about the rows. It is not like you might imagine that
each row was liked to a certain kinematic property in the model (e.g. a
kinematic measure), at least it does not have to be like this. A row can, in
general, be associated with any combination of kinematics.
However, in the current format, I think that each row is actually associated
with one degree of freedom of a segment; so the first six rows are first 3
translational then 3 rotational degrees of freedom of the first segment and
I cannot recall whether the file also contains a list of segments name, but
if so, this list is ordered like these blocks of 6 rows.
I state it this way because there is no guarantee that it will stay like
this for all model setups. The data are outputted directly for the
computational kernel of AnyBody, so it will reflect whatever algorithm that
is forming the equations of motion.
The columns of Cm each correspond to one muscle and they are ordered like
the list of “Strong Muscles” in the file.
Similarly, each column of Cr corresponds to a component of a reaction force
with Type equal to On. As far as I recall, the names of the reaction force
are not outputted to the file.
Could you explain what kind of information you would like and the task you
need it for?
We are always open for improvements.
If you for instance are using the equations to do your own muscle
recruitment analysis in external software or your own code, we would be very
glad to know what criteria you are looking for (but obviously didn’t find)
Michael Damsgaard, AnyBody Support
From: email@example.com [mailto:firstname.lastname@example.org] On Behalf
Sent: Friday, August 01, 2008 13:11
Subject: [AnyScript] Re: Equations of motion
I have figured out how Cm, Cr, and R are used, but I am unsure about
what the rows and columns correspond to. Is there a way to list out
each row or column name such as which muscle or DOF they correspond to?
— In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com> ps.com,
“chrisjgatti” <cjgatti@…> wrote:
> Check that … R is 1 x 114. Excel combined some cells initially.
> — In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com> ps.com,
“chrisjgatti” <cjgatti@> wrote:
> > I see in the reference manual that the equations of motion can be
> > exported using EquilEqExportFileName inside AnyBodyStudy. I have
> > exported these as a text file and could use some help deciphering what
> > is output.
> > First, all of the segments are listed and I understand that. Then,
> > muscles are listed twice; the first time they are just named ‘Muscles’
> > and the second, they are named ‘Strong Muscles’, but both groups have
> > the same muscles listed (172 in the model including extraneous muscles
> > like th GHReaction muscles…which is more than the 114 in the arm
> > model I am using). What is the difference between ‘Muscles’ and
> > ‘Strong Muscles’?
> > Then there is actual data, with variable names t, Cm, Cr, and R. What
> > are the last three? Cm is 114 x 172 (rows x columns), so I assume has
> > something to do with the 114 real muscles and the 172 muscles listed
> > at the top of the file. Cr is 114 x 79 and I don’t know what the 79
> > corresponds to. R is 1 x 100 and I don’t know what this is either.
> > What is the general form of the equations with respect to the output
> > variables? Any other hints or tips about these equations of motion
> > would be appreciated as well. Thanks.
> > Chris
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