Position and orientation of cervical vertebrae

[nevermind9687]

Hi!

I’m a new anybody user and am currently working on a model of a car driver which is based on the airline passenger from AMMRV1.2. So far I added a steering wheel to it and connected the person’s hands to it. During my analysis I want to look at muscle activity during several movements of the cervical spine and would need to determine the motion of each vertebra. Obviously C1-C7 are defined (HumanModel.BodyModel.Trunk.SegmentsCervicalSpine) but when changing the neck extension (either in JointsAndDrivers or JntPos), only the skull is moving relative to C1. I was not able to find where to define the 3D position of all other vertebrae. Could anyone tell me where to find it in this model? And how do I define the position over time? Do I just give it a starting and an end point?

I’m looking forward to readin some thaughts about this!

Thank you very much in advance!

[sdendorfer (Sebastian Dendorfer)]

Hi,
You have to include the TrunkNeck Model, this can be done in the BodyModel file. Then you may have to change some drivers, please have a look at the Freeposture model. In this model a lot of standard drivers (also for the SkullTrunk) are included. The motion can be specified with a simple driver stating start position and velocity of the motion or with more advanced markers like interpolation drivers using data sets (see e.g. http://wiki.anyscript.org/index.php/Tips_and_tricks#Use_a_simple_text_file_to_drive_a_model). But there are even more options, please have a look at the tutorials and the reference manual.
Best regards,
Sebastian

[nevermind9687]

Dear Sebastian!

Thank you for your quick and informative reply to my question. The only thing which is not clear to me is where I find the TrunkNeck Model. I wasn’t able to find it in the repository (AMMRV1.2 and version 1.0 of AMMR).

Thank you very much!
Ilka

[toerholm (Søren Tørholm)]

Dear Ilka,

The TrunkNeck model has been part of the repository for a long time.

For an example on who to include it please see the SeatedHumanFullwithNeck model it includes it.

Normally it is included into the model by setting a switch in the BodyPartSetup.any file.

Best regards
Søren

[sdendorfer (Sebastian Dendorfer)]

@nevermind9687

Hey Sebastian,

sorry for my late reply this time. I wtill didn't get much further wit the issue as I have to admit. I had a look at the Trunk/Neck model (AMMRV1.2/Body/AAUHuman/TrunkNeck/SegmentsCervicalSpine.any) but am still not sure about how to change the position/orientation of the vertebrae over time. As I understand it right from the tutorials I need to define an initial position (r0) and an initial velocity (rDot0) in order to do that. Is that correct?

In the file mentioned above I get the following for each vertebra:

AnySeg C2Seg = {

r0= .C3Seg.C3C2JntNode.sRel*.C3Seg.Axes0'+.C3Seg.r0-C3C2JntNode.sRel*Axes0';

AnyFunTransform3D &Scale =..ScalingTrunk.Cervical.ScaleFunction;

AnyVar MassS = ..Scaling.MassScaling.Cervical.MassScale;

AnyVar MassStandard = ..StandardParameters.CervicalSpine.Mass*0.153;

Mass = MassS*MassStandard;           
Jii = {0.00025,0.00048,0.00025};

sCoM = Scale({0.034-0.008,0.561,0.0});
  JaboutCoMOnOff = On;
AnyRefNode C3C2JntNode = {sRel = .Scale({0.031,0.543,0.0});};

AnyRefNode C2C1JntNode = {
  sRel = .Scale({0.035,0.574,0.0});
  AnyDrawNodes DrwNode = {
    ScaleXYZ = {0.003,0.003,0.003};
    RGB = {1, 0, 0};
  };
};

I don't understand the entry of r0 to be honest. I would have expected it to be in a regular (x, y, z) format. Do I need to add rDot0 here in order to make the vertebra move over time?

I'm sorry for asking you those basic questions but for some reason this issue is quite unclear to be at the moment.

Kind regards,
Ilka

[quote=sdendorfer]Hi Ilka,
sorry, I was travelling, has this been resolved now?
Best regards,
Sebastian

[/QUOTE]

Hi Ilka,
no, you don't have to define the r0. The r0 values are used for inital positioning of the segments. So it may be overruled be any other kinematic contraints you set. What you have to do is to include some more drivers for the Cervical spine. I modified the Airline Passenger model - included the TrunkNeck and some Drivers. You can set the motion of the Cervical spine now in the Mannequin file. I hope this helps.
Best regards,
Sebastian

[nevermind9687]

Dear Sebastian,
thank you very much for sending me the modified file. However, I do get an error when trying to load the file:
ERROR(SCR.PRS9) : F:/A…y/A…2/A…n/E…s/A…w/JointsAndDrivers.any : ‘SkullThoraxFlexion’ : Unresolved object
Kind regards,
Ilka

[sdendorfer (Sebastian Dendorfer)]

Hi Ilka,
please have a look at the BodyModel file (included in the main file. Here you have to set Trunk to 0 and TrunkNeck to 1.
Best regards,
Sebastian