Hi Dieter
I do not know your joint configuration, but if you have muscles spanning
multiple joints it could be, that a muscle creating a flexion moment around
the knee at the same time will create for example a eversion moment of the
ankle. If the momentarm for the eversion is too large there might not be
other muscles around this joint to counter balance it. This may prevent this
muscle from creating a knee flexion moment, so you might see activity only
in muscles spanning one joint.
So the explanation to problem can be related to the ratios between the
moment arms of the different joints, but it could also be that some muscles
are missing in the model.
I think you should try to identify which dof is causing the problem, by
introducing reaction forces.
Then look at the moment arms on the muscles spanning this joint, and the
muscle configuration.
Hope this helps you move on.
Best regards
Søren, AnyBody Support
From: anyscript@yahoogroups.com [mailto:anyscript@yahoogroups.com] On Behalf
Of dieterkassgim
Sent: 15 April 2008 13:08
To: anyscript@yahoogroups.com
Subject: [AnyScript] Re: Only one muscle does all the work
Hi Mark,
I use the basic AnyMuscleModel for all muscles which are linked to
AnyViaPointMuscles.
Regards,
Dieter
— In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com> ps.com, Mark
de Zee <mdz@…> wrote:
>
> Hello Dieter,
>
> Which muscle model do you use?
>
> In case you use the 3-element muscle model, it might be that many
of the
> muscles do not have strength, because of a too long tendon length.
In
> that case a muscle calibration is necessary.
>
> Regards, Mark
>
> dieterkassgim wrote:
> >
> > Hello John and Sylvain,
> >
> > thanks for your answers. I also thought that it has something to
do
> > with the optimization criterion. I already use the default
> > MinMaxSimplex recruitment solver. But I also tried different
methods
> > and “played” with the parameters but it always leads to similar
> > results.
> >
> > Well I turned the knee joint reaction type to {On} and indeed the
> > overreaction has disappeared. But with 81 muscles I still don’t
> > exactly know where to begin with.
> >
> > Regards,
> >
> > Dieter
> > –
> > — In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com> ps.com
<mailto:anyscript%40yahoogroups.com>,
> > “John Rasmussen” <jr@> wrote:
> > >
> > > Hi Dieter,
> > >
> > > Sylvain’s proposal is a good one.
> > >
> > > It just ocurred to me that the behavior you describe is also
> > typical
> > > for a case where the muscles are recruited by a linear criterion
> > > rather than the usual min/max criterion in AnyBody. This can
happen
> > > if you set the variable RecruitmentLpPenalty too large in the
study
> > > section of your model. For more information about this, have a
look
> > > at the tutorial named “A study of studies”.
> > >
> > > Best regards,
> > > John
> > >
> > > > — In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com>
ps.com
> > <mailto:anyscript%40yahoogroups.com>,
> > “dieterkassgim” <dieterkassgim@>
> > > > wrote:
> > > > >
> > > > > Hello everybody,
> > > > >
> > > > > I’m working on a rat model which I’m trying to simulate with
> > > AnyBody.
> > > > > The muscle definitions and motion data base on measurements
on
> > > real
> > > > > rats. The problem that I have is that one calve muscle is
doing
> > > > > almost all of the activity. Its F0 value is highly exceeded
and
> > > > > although there are sufficient muscle connections, the
remaining
> > > > > muscles are near zero. I know it is hard to analyse such a
> > > problem
> > > > > with so little informations but I thought maybe somebody has
> > > already
> > > > > had similar trouble and knows the root of this problem.
> > > > >
> > > > > Regards,
> > > > >
> > > > > Dieter
> > > > >
> > > >
> > >
> >
> >
>
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