Hi Pierre
The example on the user defined muscle is based on the interpolation
functions, but it could also have been equations like yours.
In principle you can write your own equations which are based on muscle
length and velocity.
So something in this direction might solve you problem
AnyMuscleModelUsr1 somemodel={
f0=819;
lmt=somemusclename.Lmt; //length on of the muscle depending on time …
lo = 0.44???; // the initial length of the muscle
eps = (lmt - lo)/lo; // deformation of the muscle
S=fo*exp(-((eps+1).^(-0.4129)-1).^2/(0.105981));
};
I can not give you all the formulas of the three element model that would be
too much… it fact this muscle model contains a numeric solver that solved
the internal dof of the muscles. This internal dof is the tendon length. The
user defined model does not allow you to have a numeric solver but except
from this you can do almost as you like…
We hope to add more info in the documentation on this topic at some point,
but right now it is not there, sorry.
Best regards
Søren, AnyBody Support
From: anyscript@yahoogroups.com [mailto:anyscript@yahoogroups.com] On Behalf
Of Pierre-Olivier Lemieux
Sent: 13 May 2008 03:30
To: anyscript@yahoogroups.com
Subject: [AnyScript] Re: Muscle models two elements linear
Hi guys,
I try to use a new muscle model. Here is the way that I write
it in Matlab :
f0 = 819;
lo = lm(1); % the initial length of the muscle
eps = (lm - lo)/lo; % deformation of the muscle
Sm = f0*exp(-((eps+1).^(-0.4129)-1).^2/(0.105981));
I want to know hot to write it in AnyBody. I checked the exemple
'UserDefinedMuscle.any ', but I think that it’s not exactly what I
need to know.
I have an other question. Can it be possible to know the exact
formulas of the 3 element type model that you propose? I’ve found what
I believe to be the V0 formula for this model and it gives me :
V0 = -Lfbar*(K1 + K2*Fcfast)
But I’m still not sure about the rest of the formulas.
Thank you for your support.
Pierre
— In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com> ps.com,
“AnyBody Support” <support@…> wrote:
>
> Hi,
>
> Yes it sounds reasonable. I understand your 2D model is in the plane
> of the scapula. I think you can use the same value for the deltoid in
> the 2D model.
> It is a good idea to look at the tutorials, lot of things are well
> explained there.
>
> Best regards,
> Sylvain, AnyBody Support.
>
>
>
>
> — In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com> ps.com,
“Pierre-Olivier Lemieux”
> <pothekid@> wrote:
> >
> > Hi guys,
> > thank you for you help. I did the calibration for the two
> > muscle models (2E lin & 3E). However, I’ve seen that in the 3D model
> > of the upper arm, the calibration is done with a 10 degrees
> abduction
> > for the scapular deltoid. I consider that the mean deltoid is
> > representative of the abduction in the plane of the scapula. Thus,
> do
> > you think that I can use the same value for my 2D model
> calibration ?
> >
> > I’ve found added information about the muscle models on the new
> > updated tutorials. Before, I was working with the 2006 versions.
> >
> > Thank you again
> >
> > Pierre
> >
> >
> > — In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com> ps.com,
“AnyBody Support” <support@>
> wrote:
> > >
> > > Hi Pierre Olivier,
> > >
> > > As you understood, the muscle’s neutral position is the position
> (for
> > > a certain movement) where the muscle has is optimal strength.
> That
> > > mean at this position the muscle is able to provide his maximum
> force
> > > F0. This position is typically the one where you need the more
> your
> > > muscle during the movement. For example if you lift some weight
> with
> > > your arm using your biceps, you will feel the position you are
> > > stronger is for an elbow flexion of approximately 90 degrees.
> This is
> > > where your biceps has his optimal strength. We use this
> assumption
> > > for the calibration. You may see the calibration sequence drive
> the
> > > body in different positions, they are chosen so that for each
> > > position a set of muscle is in the position where they are
> supposed
> > > to be the strongest.
> > >
> > > The aim of the calibration is to adjust the tendon length so that
> the
> > > muscle (the contractile element) has is optimal length
> (corresponding
> > > to his optimal strength) at the neutral position explained above.
> The
> > > two elements model also takes into account the tendon length and
> the
> > > contractile element length. So the problem is the same as for the
> > > three elements model: unless you already know the appropriate
> tendon
> > > length, you should run a calibration sequence. If you don’t run
> it
> > > you take the risk to get over stretched muscles without strength.
> > >
> > > Best regards,
> > > Sylvain, AnyBody Support.
> > >
> > >
> > >
> > >
> > > — In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com>
ps.com, “Pierre-Olivier Lemieux”
> > > <pothekid@> wrote:
> > > >
> > > > Hi guys,
> > > > I’ve an other question regarding the muscle models. What
> is
> > > the
> > > > muscle’s neutral position ? I know that it is related to the
> > > > calibration and I know that at this position, the muscle has is
> > > > optimal strength, but does it means that’s because it does not
> > > develop
> > > > any force ? What about the calibration, do I need to do it for
> the
> > > > “two elements model” also ?
> > > >
> > > > Thank you for the support.
> > > >
> > > > Pierre
> > > >
> > > > — In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com>
ps.com, “Pierre-Olivier Lemieux”
> > > > <pothekid@> wrote:
> > > > >
> > > > > Hi John,
> > > > > thank you for your advices. Yes, eventually I will
> come to
> > > the
> > > > > 3-elements model soon, but before I have to review the 2
> elements
> > > to
> > > > > prove that its not sufficient for what I need. Also, my
> > > supervisors
> > > > > asked me to explain them the way that these models works. At
> the
> > > same
> > > > > time, it allow me to know a little bit more about the
> software.
> > > > >
> > > > > I saw that in the tutorial, they put a minimal value of -0.3
> m/s
> > > for
> > > > > the V0 parameter, is it a good value to use for the deltoid
> > > muscle for
> > > > > instance ? In my model, the velocity is very reduced and I
> think
> > > that
> > > > > it would not have any effect on the strength of the muscle,
> but I
> > > > > still want to know what is the limit of contraction velocity
> for
> > > the
> > > > > muscle. If you don’t know, it’s ok, I will find a estimated
> value
> > > by
> > > > > doing some tests.
> > > > >
> > > > > For the slow and fast twitch, it seems to have some
> differences
> > > > > between the divisions of the deltoid muscle, from the new
> study of
> > > > > Gorelick and Brown (2007). However, the ‘Fcfast’ of all the
> > > divisions
> > > > > in AnyBody are set to 40%. Maybe it should have some
> improvement
> > > to
> > > > > the model by considering this article.
> > > > >
> > > > > Here is the complete reference, if you didn’t read it
> already :
> > > > >
> > > > > Gorelick, M., et J. Brown. 2007. « Mechanomyographic
> assessment of
> > > > > contractile properties within seven segments of the human
> deltoid
> > > > > muscle ». European Journal of Applied Physiology, vol. 100,
> no 1,
> > > p.
> > > > > 35-44.
> > > > >
> > > > > Thank you for your support and have a great summer.
> > > > >
> > > > > Pierre
> > > > >
> > > > > — In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com>
ps.com, “John Rasmussen” <jr@>
> wrote:
> > > > > >
> > > > > > Hi Pierre-Olivier,
> > > > > >
> > > > > > Fast twitch fibers are fast and slow twitch fibers are
> slow. So
> > > if
> > > > > > the lateral deltoid mostly has slow twitch fibers then it
> is
> > > likely
> > > > > > to be MORE sensible to velocity and you should consequently
> use
> > > a LOW
> > > > > > value of V0. Remember, V0 is the velocity at which the
> muscle
> > > > > > completely loses its strength.
> > > > > >
> > > > > > Have you considered using the three-element muscle mudel
> > > instead? It
> > > > > > allows you to input fiber length and the ratio of fast to
> slow
> > > twitch
> > > > > > fibers, and you do not have to worry about what V0 is. The
> > > muscle
> > > > > > model works that out automatically.
> > > > > >
> > > > > > Best regards,
> > > > > > John
> > > > > >
> > > > > >
> > > > > > — In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com>
ps.com, “Pierre-Olivier Lemieux”
> > > > > > <pothekid@> wrote:
> > > > > > >
> > > > > > > Hi guys,
> > > > > > > I’m working on muscle models of Anybody and I try
> to
> > > explain
> > > > > > > how they work for an abduction of the arm as an example.
> For
> > > the
> > > > > > > simple model, I’ve no problem. However, for the two
> elements
> > > linear
> > > > > > > model (2Elin), I have difficulties to find a reasonable
> value
> > > > > > for ‘V0’
> > > > > > > parameter for the deltoid muscle. There is not a lot of
> > > litterature
> > > > > > > for this model. From what I know, the lateral part of the
> > > deltoid is
> > > > > > > responsible for the abduction and it is composed mostly
> of
> > > slow
> > > > > > twitch
> > > > > > > fibres. Can i put a high value of ‘V0’ because of that ?
> I
> > > mean, if
> > > > > > > this part of the muscle is composed of slow twitch
> fibres,
> > > does it
> > > > > > > make it not sensitive to contraction velocity ? I’m not
> very
> > > sure to
> > > > > > > understand well this parameter.
> > > > > > >
> > > > > > > Thank you for you help
> > > > > > >
> > > > > > > Pierre
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>
[Non-text portions of this message have been removed]