Hi Sylvain and Mark,
i modified my Human Jaw model with 6 muscles on each side (2
temporalis,1 masseter,medial and lateral pterygoid and digastrics). I
am able to run the model with your motion capture
data(ChewingRight.txt). However i have created my own motion capture
data “HumanJaw.txt” which causes error halfway through the simulation.
I get same error message “Muscle recruitment analysis failed”. I
beleive this time i got both the jaw closer and opening muscles
modeled. Please provide valuable suggestions to improve it. Also can
you please tell me that parameters that should be scaled while
modeling for different subjects and how they should be done ( for
instance how to determine fiberlength, strength etc given in
“scalingstandard.any”). Could you please explain me how scaling file
works? Please find attached folder “HumanJawModel.rar” and
jawmodel2.any file in files section.
If you look at the model view when the analysis stops you will see
the digastrics muscles become a blue line. They are too short and
cannot pull anymore. So there are no longer forces to open the
mandible and the analysis fails. This happens because the jaw opens
too much regarding to the muscular structure. The solution is to
decrease the jaw range of motion or change the attachment point of
the digastrics muscles to be further from the mandible, or both
solutions at the same time.
About scaling: there are several parameters in the ScalingStandard
file. This file is normally used to give the standard values to the
model. To change those values we usually use different scaling file
like ScalingUniform or ScalingLengthMassFat. However those files
exist for the body but not for the jaw. So you can just modify the
ScalingStandard file that you have. The parameter MassScaling allows
you to scale the mass of the segments using the coefficient as a
percentage of the standard mass. Same thing for the Strength and
FiberLenght, the coefficient controls directly the value of the
parameters of the muscles. The GeometricalScaling has to be slightly
modified, you have to replace the AnyFunTransform3DIdentity by an
AnyFunTransform3DLin, then enter the coefficients to scale the
segment in the three dimensions. You can look at the other scaling
files of the repository (ScalingUniform or ScalingLengthMassFat) to
have an example of how to do it.
Of course you need to collect data from the subject you want to model
to input the correct values in the scaling file.
Best regards,
Sylvain, AnyBody Support.
— In anyscript@yahoogroups.com, “K Srikanth”
<srikanth_kannan84@…> wrote:
>
> Hi Sylvain and Mark,
> i modified my Human Jaw model with 6 muscles on each side (2
> temporalis,1 masseter,medial and lateral pterygoid and digastrics).
I
> am able to run the model with your motion capture
> data(ChewingRight.txt). However i have created my own motion capture
> data “HumanJaw.txt” which causes error halfway through the
simulation.
> I get same error message “Muscle recruitment analysis failed”. I
> beleive this time i got both the jaw closer and opening muscles
> modeled. Please provide valuable suggestions to improve it. Also can
> you please tell me that parameters that should be scaled while
> modeling for different subjects and how they should be done ( for
> instance how to determine fiberlength, strength etc given in
> “scalingstandard.any”). Could you please explain me how scaling file
> works? Please find attached folder “HumanJawModel.rar” and
> jawmodel2.any file in files section.
>
> thanks
> srikanth
>
In the case of a Human Jaw model in AnyBody repository, first case is
to perform chewing action with simulated chewing force data. Can
anybody please tell me how to simulate chewing force? From the model
it seems for case 1 they are not real measurements. are we supposed to
use any function to generate the text file SimulatedForceChewing.txt.
In Case 1 in the repository kinematics are measured, but indeed the
chewing force input is constructed, because I was not able to measure
the forces during chewing. It is really just for demonstration and the
simulated chewing forces are probably not really realistic.
I used the the z-coordinate of the measured incisor position for
constructing the SimulatedForceChewing.txt in such a way that the force
was minimal at maximum gape and maximum at minimum gape.
Regards,
Mark de Zee
K Srikanth wrote:
>
> In the case of a Human Jaw model in AnyBody repository, first case is
> to perform chewing action with simulated chewing force data. Can
> anybody please tell me how to simulate chewing force? From the model
> it seems for case 1 they are not real measurements. are we supposed to
> use any function to generate the text file SimulatedForceChewing.txt.
>
> thanks
> srikanth
>
>
Hi Mark
I am guessing that you have used F=ma principle and calculated the force based
on the acceleration of the incisor point? Is this assumption right? But the
forces seem to be reaching a value of about 170N which looks like really large
acceleration. i know that this is just for demo purpose but has some sort of
realism. Even i have the position, velocity and acceleration data of the
incisor point but i am getting less force based on above principle. It would be
great if you can clarify the procedure of creating the simulated force.
thanks
srikanth
Srikanth Kannan
Teaching & Research Assistant
Automation Robotics & Mechatronics Lab
State University of New York at Buffalo
Buffalo,NY,USA-14221
----- Original Message ----
From: Mark de Zee <mdz@hst.aau.dk>
To: anyscript@yahoogroups.com
Sent: Thursday, 31 July, 2008 3:32:58 AM
Subject: Re: [AnyScript] Human Jaw Model
Dear Srikanth,
In Case 1 in the repository kinematics are measured, but indeed the
chewing force input is constructed, because I was not able to measure
the forces during chewing. It is really just for demonstration and the
simulated chewing forces are probably not really realistic.
I used the the z-coordinate of the measured incisor position for
constructing the SimulatedForceChewi ng.txt in such a way that the force
was minimal at maximum gape and maximum at minimum gape.
Regards,
Mark de Zee
K Srikanth wrote:
>
> In the case of a Human Jaw model in AnyBody repository, first case is
> to perform chewing action with simulated chewing force data. Can
> anybody please tell me how to simulate chewing force? From the model
> it seems for case 1 they are not real measurements. are we supposed to
> use any function to generate the text file SimulatedForceChewi ng.txt.
>
> thanks
> srikanth
>
>
Connect with friends all over the world. Get Yahoo! India Messenger at
Hi Mark
I am guessing that you have used F=ma principle and calculated the force based
on the acceleration of the incisor point? Is this assumption right? But the
forces seem to be reaching a value of about 170N which looks like really large
acceleration. i know that this is just for demo purpose but has some sort of
realism. Even i have the position, velocity and acceleration data of the
incisor point but i am getting less force based on above principle. It would be
great if you can clarify the procedure of creating the simulated force.
thanks
srikanth
Srikanth Kannan
Teaching & Research Assistant
Automation Robotics & Mechatronics Lab
State University of New York at Buffalo
Buffalo,NY,USA-14221
----- Original Message ----
From: Mark de Zee <mdz@hst.aau.dk>
To: anyscript@yahoogroups.com
Sent: Thursday, 31 July, 2008 3:32:58 AM
Subject: Re: [AnyScript] Human Jaw Model
Dear Srikanth,
In Case 1 in the repository kinematics are measured, but indeed the
chewing force input is constructed, because I was not able to measure
the forces during chewing. It is really just for demonstration and the
simulated chewing forces are probably not really realistic.
I used the the z-coordinate of the measured incisor position for
constructing the SimulatedForceChewi ng.txt in such a way that the force
was minimal at maximum gape and maximum at minimum gape.
Regards,
Mark de Zee
K Srikanth wrote:
>
> In the case of a Human Jaw model in AnyBody repository, first case is
> to perform chewing action with simulated chewing force data. Can
> anybody please tell me how to simulate chewing force? From the model
> it seems for case 1 they are not real measurements. are we supposed to
> use any function to generate the text file SimulatedForceChewi ng.txt.
>
> thanks
> srikanth
>
>
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Your assumption is not right. The chewing force is dependent on how hard
you chew on the food bolus inside the mouth. It is this force we would
like to have as an external input force in our inverse dynamics based
model. Ideally you would like to measure it, but that is almost impossible.
In chewing and clenching one can reach high forces, the jaw muscles are
very strong. I have just used the z-coordinate of the incisor for the
timing of the chewing force assuming that the amplitude of the chewing
force has some direct relation with opening and closing.
I just want to stress, that I don’t know if my constructed chewing force
has any realism. I do know that the amplitude of 170 N is definitely in
the range what you could expect in chewing some hard stuff.
Regards, Mark
Srikanth Kannan wrote:
>
> Hi Mark
> I am guessing that you have used F=ma principle and calculated the
> force based on the acceleration of the incisor point? Is this
> assumption right? But the forces seem to be reaching a value of about
> 170N which looks like really large acceleration. i know that this is
> just for demo purpose but has some sort of realism. Even i have the
> position, velocity and acceleration data of the incisor point but i am
> getting less force based on above principle. It would be great if you
> can clarify the procedure of creating the simulated force.
>
> thanks
> srikanth
>
> Srikanth Kannan
> Teaching & Research Assistant
> Automation Robotics & Mechatronics Lab
> State University of New York at Buffalo
> Buffalo,NY,USA-14221
>
> ----- Original Message ----
> From: Mark de Zee <mdz@hst.aau.dk <mailto:mdz%40hst.aau.dk>>
> To: anyscript@yahoogroups.com <mailto:anyscript%40yahoogroups.com>
> Sent: Thursday, 31 July, 2008 3:32:58 AM
> Subject: Re: [AnyScript] Human Jaw Model
>
> Dear Srikanth,
>
> In Case 1 in the repository kinematics are measured, but indeed the
> chewing force input is constructed, because I was not able to measure
> the forces during chewing. It is really just for demonstration and the
> simulated chewing forces are probably not really realistic.
>
> I used the the z-coordinate of the measured incisor position for
> constructing the SimulatedForceChewi ng.txt in such a way that the force
> was minimal at maximum gape and maximum at minimum gape.
>
> Regards,
> Mark de Zee
>
> K Srikanth wrote:
> >
> > In the case of a Human Jaw model in AnyBody repository, first case is
> > to perform chewing action with simulated chewing force data. Can
> > anybody please tell me how to simulate chewing force? From the model
> > it seems for case 1 they are not real measurements. are we supposed to
> > use any function to generate the text file SimulatedForceChewi ng.txt.
> >
> > thanks
> > srikanth
> >
> >
>
> Connect with friends all over the world. Get Yahoo! India Messenger at
> http://in.messenger.yahoo.com/?wm=n/
> <http://in.messenger.yahoo.com/?wm=n/>
>
> [Non-text portions of this message have been removed]
>
>