Forums Anyscript.org  

Go Back   Forums Anyscript.org > Self-Supported Forum > AnyBody Model Repository

Notices

Reply
 
Thread Tools Display Modes
  #11  
Old 04-18-2013, 08:26 PM
sip0sip sip0sip is offline
Junior Member
 
Join Date: Feb 2013
Posts: 28
Default condyles on a plane

Hi,
I have a question concerning the definition (restrictions) of the condyles node movement on a plane (still the Mark de Zee’s mandible model from the repository). It was partially mentioned in an older post here http://forum.anyscript.org/showthrea...light=mandible. If I understand it right, the only part of the code that it supposed to govern the movement of the condyles on a plane is in the seg.any file: AngleY, AngleX, and subsequently TransY, TransX_R, TransX_L. The transformations (Trans) are then used to rotate the condyles’ nodes around the axis X and Y (mirrored for left and right condyle). And as I understand, in a newer AnyBody version the function RotMat could be used instead (only an easier way of writing down the transformation matrix).

However, I don’t see, how such a „plane“ transformation can keep the points‘ movement on a plane. I would expect some constraints „node on a plane“ as it was once demonstrated in an example (I don’t remember anymore where) - a plane was defined by three points, some of them can move, and the movement of one point was constrained to the plane. This I don’t see from Mark’s definition. What am I missing?

Thanks for any comment
Michala
Reply With Quote
  #12  
Old 04-19-2013, 03:49 PM
msan00 msan00 is offline
Member
 
Join Date: Apr 2009
Posts: 58
Default

Hi Michala,

The joints are defined in the Jnt.any file (found in the body part of the repository next to the Seg.any file). The remaining drivers and constraints are defined in the JointsAndDrivers file next to the main file.

Best regards
Michael Skipper Andersen
Associate Professor
The AnyBody Research Group
Reply With Quote
  #13  
Old 04-19-2013, 04:58 PM
sip0sip sip0sip is offline
Junior Member
 
Join Date: Feb 2013
Posts: 28
Default

Hi Michael,
Thank you for your answer. However, it did not help me much. I went through the files even before and the problem is that the temporomandibular joint is kind of loose joint, by which I mean that there is none of the “classic” joints useful (rotation, spherical, etc.). If I did not miss anything, in the seg.any only the nodes for the condyles, incisor points and muscle attachments are defined (together with the transformations) on the skull and mandible.

And then in the Jnt.any the drivers for the “joint” are defined. So maybe here I don’t fully understand what is going on. Here, for the left and right joints the drivers and constraints are defined in the same way.

First AnyKinLinear TMJ_JntR (or TMJ_JntL) measures the translation (in 3D) between the TMJ_Node on the Skull and on the Mandible.

Than the AnyKinMeasureOrg TMJ_JntR_Z (TMJ_JntL_Z) just „picks“ the z-coordinate from the above mentioned kinematic measure (MeasureOrganizer={2}).

Finaly, the drive AnyKinEqSimpleDriver TMJ_JntR_Z_Constraint (TMJ_JntL_Z_Constraint) constraints the movement in z-direction (DriverPos = {0.0};
DriverVel = {0.0}; Reaction.Type = {Off};).

Here, I am not really sure what the AnyGeneralMuscle does (control the force direction?)

AnyGeneralMuscle ReactionForceTMJ_R= {
AnyMuscleModel &ref=.ArtificialMuscle;
AnyKinMeasure &ref2=.TMJ_JntR_Z;
ForceDirection=-1;
};

So all this was actually only about the constraint in the z-direction. Here to be sure – the z-direction means up, right? In the beginning I thought that this is the mediolateral constraint of the joint, but now, at least after the visualization of the global coordinate system, it looks like the constraint in the vertical direction (and also from the results the movement of the condyle in y-direction is zero). But maybe here I did not fully get what the AnyKinEqSimpleDriver TMJ_JntR_Z_Constraint is doing. The variables DriverPos = {0.0} and DriverVel = {0.0} do not mean that this is constantly zero, but these are the initial position and velocity (?).

Than in the file JointsAndDriversChewing.any the movement and constraints in the mediolateral direction are stated. Here the 3D movement of the incisor point in time is loaded. And the movement of the left TMJ is set to 0 (AnyKinMeasureOrg TMJ_JntL_Y, AnyKinEqSimpleDriver TMJ_JntL_Y_Driver).


So, to get back to my question – how those Z-constraints ensure, that the movement of the condyles is on a plane?

Thanks for your time
Michala
Reply With Quote
  #14  
Old 04-19-2013, 05:35 PM
msan00 msan00 is offline
Member
 
Join Date: Apr 2009
Posts: 58
Default

Hi Michala,

What is in the Jnt.any file are exactly the drivers (also constraint equations) that specify that the condyles are moving on a plane. The
AnyKinEqSimpleDriver TMJ_JntR_Z_Constraint driver specifies that the z-component of the vector between the two points should be zero. The DriverPos={0.0}; and DriverVel={0.0}; do mean that the values should be constantly zero. Only case where this is not true is when the kinematic driver is specifed as force-dependent, but that is not used in this model.

Normally, active reactions related to kinematic constraints are bilateral. However, in this model, Mark de Zee wanted the reaction forces to be unilateral, representing the contact forces of the joints. That is why the reaction force of the kinematic constraint equations are switched off and instead replaced by a general muscle that only can provide a force in one direction.

The constraints in the JointsAndDrivers file specify the medial/lateral direction (which is just fixed at a given position) and the mouth opening.

I would recommend that go through the tutorial "The mechanical elements" for a better understanding of kinematic measures and drivers.

Best regards
Michael Skipper Andersen
Associate Professor
The AnyBody Research Group
Reply With Quote
  #15  
Old 04-19-2013, 09:42 PM
sip0sip sip0sip is offline
Junior Member
 
Join Date: Feb 2013
Posts: 28
Default

So one more silly question. When I compare the TMJ_JntL_Y_Driver and TMJ_JntL_Z_Constraint they both are basically the same – AnyKinLinear (for the left joint). Then the difference is that for the TMJ_JntL_Y the MeasureOrganizer={1} and for TMJ_JntL_Z it is MeasureOrganizer={2} (makes sense). The AnyKinEqSimpleDriver for both is the same (calling the appropriate AnyKinMeasure): DriverPos = {0.0}; DriverVel = {0.0}; Reaction.Type = {Off}. So what still surprises me is that in the end the displacement/movement of the condyles in y (TMJ_JntL_Y_Driver) is zero, while z-displacement of the condyle changes (TMJ_JntL_Z_Constraint) in time. Or does the AnyGeneralMuscle applied on the TMJ_JntL_Z plays here a role?

Regards
Michala
Reply With Quote
  #16  
Old 04-19-2013, 10:12 PM
msan00 msan00 is offline
Member
 
Join Date: Apr 2009
Posts: 58
Default

Hi Michala,

When the kinematics is solved, both the y-component (due to the driver in the JointsAndDrivers file) and the z-component of the driver for each of the condyles (due to the drivers in the Jnt.any file) will be zero. I think what you have missed is in which reference frame these coordinates are expressed. If you look in the Jnt.any file then you will see that the linear measure for both condyles have Ref=0:

//The right TMJ
AnyKinLinear TMJ_JntR={
AnyRefNode &SkullRef = ..Seg.Skull.TMJ_NodeR;
AnyRefNode &MandibleRef = ..Seg.Mandible.TMJ_NodeR;
Ref=0;
};

This means that the vector between the two nodes is expressed in the first mentioned reference frame. In this case the Skull.TMJ_NodeR reference frame for the right side and the Skull.TMJ_NodeL for the left side. If you plot both reference frames of the TMJ on the mandible and on the skull, you will see that the right condyle remains in the x-y plane of the Skull.TMJ_NodeR reference frame. Similarly for the left condyle.

I hope this helps.

Best regards
Michael Skipper Andersen
Associate Professor
The AnyBody Research Group
Reply With Quote
  #17  
Old 04-24-2013, 02:35 PM
sip0sip sip0sip is offline
Junior Member
 
Join Date: Feb 2013
Posts: 28
Default

Hi Michael,


Thank you for your comments. I finally see what is going on. Among others I also had problem to realize, that I am turning the “coordinate system” of the TMJ nodes and not the whole mandible. And after realizing this together with your note about the AnyKinLinear in the local coordinate system (Ref=0) it all make sense.


Thanks a lot.
Michala
Reply With Quote
  #18  
Old 02-25-2015, 03:08 AM
aahmadi aahmadi is offline
Junior Member
 
Join Date: Feb 2015
Posts: 4
Default mandible force

Dear members,

I want to model the different reconstruction of mandible. So I need that for example by considering biting force on molar teeth, How I can get the muscle forces. Actually is there any posibility to get muscle forces by Anybody software?

Regards,
Reply With Quote
  #19  
Old 02-25-2015, 01:06 PM
aalmunajjed aalmunajjed is offline
Senior Member
 
Join Date: Mar 2011
Posts: 633
Default

The AnyBody Modeling System will compute the muscle activations and forces when you have the biting forces and the motion.

The basis model is in the repository.
__________________
Best regards, Amir

__________________
Amir Al-Munajjed, AnyBody Support

Please provide AMMR and AMS version numbers in case you send a debug model. The folder structure should follow the standard in the AMMR. This makes it a lot easier for us to answer your questions faster.

Consider to subscribe to a forum, click the 'ForumTools' link above the list of threads then select 'Subscribe to Forum'.
Reply With Quote
  #20  
Old 02-27-2015, 11:34 PM
aahmadi aahmadi is offline
Junior Member
 
Join Date: Feb 2015
Posts: 4
Default mandible force

Quote:
Originally Posted by aalmunajjed View Post
The AnyBody Modeling System will compute the muscle activations and forces when you have the biting forces and the motion.

The basis model is in the repository.
Thank you for the response.
What do you mean by the motion? I only have the biting force?
another question is that if I consider the dynamic force< can I also have muscle forces too? Is there any article or documents until I can be aware about the procedure?

Regards,
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +2. The time now is 06:13 AM.