Questions on "Muscle Modeling Webcast"

Hi,

In the following webcast:
Muscle Modeling (Dr. John Rasmussen, 6. March, 2006)
Presentation (3mb), Playback (17mb)

The slide at the bottom on page 8 (PDF note), there is a
“Length/velocity plot” surface plot.

I would like to know how did you set up the model in order to
obtain the result?
Would it be possible that you post the file here so that we
can have a look?

Another question: From my understanding, Anybody does not
consider the Mass of the muscles as part of the ‘multi-body’ system,
the mass of a ‘body part’ e.g. upper arm is lumped into the ‘upper arm
segment’. Is this correct? Or you have assume some mass properties
that you approximate using the defined muscle’s properties?

Thanks,
Leng-Feng

Hi every one,

I am facing a problem i can not open and run this file and i got an error
message:

ERROR(SCR.SCN1) : C:\Program Files\AnyBody
Technology\AnyBody.2.0\Repository.6\ARep\Aalborg\FreePostureMove\Mannequin.any(3
5) : Cannot open file : PelvisThoraxExtension.any
Model loading skipped

uf any one can help me and tell me what is the problem i will appreciate it.

thanks

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

Hi

Hi Nesreen

The error you are getting, SCR.SCN1
ERROR(SCR.SCN1)

The file may not exist, your access permission may be limitted, or it
may be locked by another operation or application (sharing
violation).

Could you check the permissions on the file?

Best regards
Christian, AnyBody Support

— In anyscript@yahoogroups.com, “Nesreen Aboulkhair”
<nesreen.aboulkhair@…> wrote:
>
> Hi every one,
>
> I am facing a problem i can not open and run this file and i got an
error message:
>
> ERROR(SCR.SCN1) : C:\Program Files\AnyBody Technology\AnyBody.2.0
\Repository.6\ARep\Aalborg\FreePostureMove\Mannequin.any(35) :
Cannot open file : PelvisThoraxExtension.any
> Model loading skipped
>
> uf any one can help me and tell me what is the problem i will
appreciate it.
>
> thanks
>
>
>
> [Non-text portions of this message have been removed]
>

Hi,

I posted the following question last friday. A guy posted another
question by reply to my question. His question is being answered. I
wonder if my question is missed in this case?

Please post your own question by posting a new message instead of hit
“reply” on others message and ask your question.

Thanks,
Leng-Feng

— Leng-Feng Lee <lengfenglee@yahoo.com> wrote:

> Hi,
>
> In the following webcast:
> Muscle Modeling (Dr. John Rasmussen, 6. March, 2006)
> Presentation (3mb), Playback (17mb)
>
> The slide at the bottom on page 8 (PDF note), there is a
> “Length/velocity plot” surface plot.
>
> I would like to know how did you set up the model in order to
> obtain the result?
> Would it be possible that you post the file here so that we
> can have a look?
>
> Another question: From my understanding, Anybody does not
> consider the Mass of the muscles as part of the ‘multi-body’
> system,
> the mass of a ‘body part’ e.g. upper arm is lumped into the ‘upper
> arm
> segment’. Is this correct? Or you have assume some mass properties
> that you approximate using the defined muscle’s properties?
>
>
> Thanks,
> Leng-Feng
>
>
>
>
>


Do You Yahoo!?
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Hi Leng-Feng,

Sorry about the delay. I did in fact miss the question in the first
place.

The figure in question is made with Matlab - not with AnyBody. We
initially implemented the muscle models in Matlab before we coded
them into AnyBody. I believe the figure is using the data of an
anatomical muscle, but I do not remember which one. We usually try
muscles at both ends of the spectrum to Fiber Length / Tendon
Length, where the muscles with small values of this ratio are the
more challenging to model.

The surface shows the different forces at some given activation
level depending on fiber length and contraction velocity. You cannot
make this directly in AnyBody because it is an inverse dynamics
system and activation is output rather than input.

However, you can set up a parameter study in AnyBody where you
suspend a single muscle between two segments and subsequently drive
the distance and velocity between the segments using a SimpleDriver.
You must also load one of the segments and fix the other one to give
the muscle something to carry.

You can then vary distance and velocity in the parameter study and
collect values for Fp, Ft, Fm and Activation. You should be able to
plot Fp directly and obtain the Fp surface from the figure.

Fm must be normalized by the activity, and Ft must be recomputed as
the normlized Fm plus Fp. If you plot those I believe you should be
able to get a similar surface in AnyBody’s AnyChart view.

Best regards,
John
The AnyBody Research Project

— In anyscript@yahoogroups.com, Leng-Feng Lee <lengfenglee@…>
wrote:
>
> Hi,
>
> I posted the following question last friday. A guy posted another
> question by reply to my question. His question is being answered. I
> wonder if my question is missed in this case?
>
> Please post your own question by posting a new message instead of
hit
> “reply” on others message and ask your question.
>
> Thanks,
> Leng-Feng
>
>
>
> — Leng-Feng Lee <lengfenglee@…> wrote:
>
> > Hi,
> >
> > In the following webcast:
> > Muscle Modeling (Dr. John Rasmussen, 6. March, 2006)
> > Presentation (3mb), Playback (17mb)
> >
> > The slide at the bottom on page 8 (PDF note), there is a
> > “Length/velocity plot” surface plot.
> >
> > I would like to know how did you set up the model in order to
> > obtain the result?
> > Would it be possible that you post the file here so that we
> > can have a look?
> >
> > Another question: From my understanding, Anybody does not
> > consider the Mass of the muscles as part of the ‘multi-body’
> > system,
> > the mass of a ‘body part’ e.g. upper arm is lumped into
the ‘upper
> > arm
> > segment’. Is this correct? Or you have assume some mass
properties
> > that you approximate using the defined muscle’s properties?
> >
> >
> > Thanks,
> > Leng-Feng
> >
> >
> >
> >
> >
>
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
>

Hello Dr. John,

Thanks for your reply. That is what I am trying to do: regenerate the
graph in AnyBody to better understand the muscle model’s reponse, and
the model you mentioned is what I have set up-I’ll take your
suggestions and see how it turns out.

Is it possible that you post the Matlab m-file(s) that you used to
generate the plot? I would like to know how you have formulate the
muscle force as a function of Lm, Lmtdot, Lmdot,etc. (and the
activation force). I am able to generate the muscle force response
given in the literature(s), but having difficulty to generate the
same result using AnyBody - which gives me some difficulty in
relating the muscle model in the literature and how AnyBody has
implemented it.

[I understand that there is a ‘dilemma’ to get the muscle force in a inverse dynamic settings as you pointed out in the tutorials and webcast-and AnyBody have adopted a way to overcome this].

Or, if you have the papers that describe the muscle model that
AnyBody implement, could you point me to the PDF file?

Thanks for your time!

Thanks,
Leng-Feng

— AnyBody Support <support@anybodytech.com> wrote:

> Hi Leng-Feng,
>
> Sorry about the delay. I did in fact miss the question in the first
>
> place.
>
> The figure in question is made with Matlab - not with AnyBody. We
> initially implemented the muscle models in Matlab before we coded
> them into AnyBody. I believe the figure is using the data of an
> anatomical muscle, but I do not remember which one. We usually try
> muscles at both ends of the spectrum to Fiber Length / Tendon
> Length, where the muscles with small values of this ratio are the
> more challenging to model.
>
> The surface shows the different forces at some given activation
> level depending on fiber length and contraction velocity. You
> cannot
> make this directly in AnyBody because it is an inverse dynamics
> system and activation is output rather than input.
>
> However, you can set up a parameter study in AnyBody where you
> suspend a single muscle between two segments and subsequently drive
>
> the distance and velocity between the segments using a
> SimpleDriver.
> You must also load one of the segments and fix the other one to
> give
> the muscle something to carry.
>
> You can then vary distance and velocity in the parameter study and
> collect values for Fp, Ft, Fm and Activation. You should be able to
>
> plot Fp directly and obtain the Fp surface from the figure.
>
> Fm must be normalized by the activity, and Ft must be recomputed as
>
> the normlized Fm plus Fp. If you plot those I believe you should be
>
> able to get a similar surface in AnyBody’s AnyChart view.
>
> Best regards,
> John
> The AnyBody Research Project
>
> — In anyscript@yahoogroups.com, Leng-Feng Lee <lengfenglee@…>
> wrote:
> >
> > Hi,
> >
> > I posted the following question last friday. A guy posted another
> > question by reply to my question. His question is being answered.
> I
> > wonder if my question is missed in this case?
> >
> > Please post your own question by posting a new message instead of
>
> hit
> > “reply” on others message and ask your question.
> >
> > Thanks,
> > Leng-Feng
> >
> >
> >
> > — Leng-Feng Lee <lengfenglee@…> wrote:
> >
> > > Hi,
> > >
> > > In the following webcast:
> > > Muscle Modeling (Dr. John Rasmussen, 6. March, 2006)
> > > Presentation (3mb), Playback (17mb)
> > >
> > > The slide at the bottom on page 8 (PDF note), there is a
> > > “Length/velocity plot” surface plot.
> > >
> > > I would like to know how did you set up the model in order to
> > > obtain the result?
> > > Would it be possible that you post the file here so that we
> > > can have a look?
> > >
> > > Another question: From my understanding, Anybody does not
> > > consider the Mass of the muscles as part of the ‘multi-body’
> > > system,
> > > the mass of a ‘body part’ e.g. upper arm is lumped into
> the ‘upper
> > > arm
> > > segment’. Is this correct? Or you have assume some mass
> properties
> > > that you approximate using the defined muscle’s properties?
> > >
> > >
> > > Thanks,
> > > Leng-Feng
> > >
> > >
> > >
> > >
> > >
> >
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Tired of spam? Yahoo! Mail has the best spam protection around
> > http://mail.yahoo.com
> >
>
>
>
>
>


Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com

Hi Leng-Feng,

> Is it possible that you post the Matlab m-file(s) that you used to
> generate the plot? I would like to know how you have formulate the
> muscle force as a function of Lm, Lmtdot, Lmdot,etc. (and the
> activation force). I am able to generate the muscle force response
> given in the literature(s), but having difficulty to generate the
> same result using AnyBody - which gives me some difficulty in
> relating the muscle model in the literature and how AnyBody has
> implemented it.

We are right now in the process of writing a publication about this
muscle model so we will keep the Matlab files to ourselves for the
time being. I hope you understand this.

I can give you the main references, though:

Daxner, T. (1997, August). Simulation von beuge- und
streckbewegungen des menschlichen knies mit dads. Ph.D.
dissertation, Institut f¨ur Mechabik der Technischen Universit
¨at Wien, A-4810 Gmunden Hochm¨ullergasse 22,
Wien. Matr.Nr.: 8825624.

Gföhler, M., T. Angeli, T. Eberharter, and P. Lugner
(1999). Dynamic simulation of cycling powered by lower
extremity muscles activiated by functional electrical simulation.
In XIIth Biomechanics Seminar, Högfors C, Editor,
pp. 101–122. vol. 12 (ISSN 1100-2247). G¨oteborg.

Unfortunately they are both difficult to get and the first one is in
German. You may check Pubmed to see what else you can find from the
same authors.

> Thanks for your reply. That is what I am trying to do:
> regenerate the
> graph in AnyBody to better understand the muscle
> model’s reponse, and
> the model you mentioned is what I have set up-I’ll take your
> suggestions and see how it turns out.

This we can help you with. If you need any help on setting the model
up, then please upload what you have and I will be happy to take a
look at it and help you get the right results out. It seems like it
could be a good model to use in our muscle modeling tutorial.

Best regards,
John