VirtuelSeg for measuring the Abdominal Volume

Dear AnyBody Team,

I have a question about abdominal pressure. As far as I understand, the VirtuelSeg is used to measure the volume change of the cylinders. The VirtuelSeg is connected to the transversus. Thus, when the transversus contracts, there is a linear displacement of the VirtuelSeg, which changes the radius of the cylinder.

In the AnyKinMeasureLinComb, the measurement of the AnyPrismaticJoint "VirtuelSegDiscJnt" is referenced.

AnyKinMeasureLinComb AbdominalVol= {

``````AnyKinMeasure& L1=.Disc1.Disc.VirtuelSegDiscJnt;
AnyKinMeasure& L2=.Disc2.Disc.VirtuelSegDiscJnt;
AnyKinMeasure& L3=.Disc3.Disc.VirtuelSegDiscJnt;
AnyKinMeasure& L4=.Disc4.Disc.VirtuelSegDiscJnt;
AnyKinMeasure& L5=.Disc5.Disc.VirtuelSegDiscJnt;

AnyKinPLine&ref7=.JointsAndDrivers.H;
``````

However, a driver is defined immediately afterwards, which sets the degree of freedom of the VirtuelSegDiscJnt.

AnyKinEqSimpleDriver drv={
AnyPrismaticJoint &ref=.VirtuelSegDiscJnt;
DriverPos={0.001};
DriverVel={0.0};
Reaction.Type={Off}
};

When I run the inverse, you can also see that L1 to L5 remain constant at 0.001 and only ref7 changes. So the volume measurement is only dependent on that of ref7.

Why is a driver used here? The contraction of the transversus no longer has any influence on the abdominal pressure?

Kind regards

Nikolas

Hi Nikolas,

Since this is inverse dynamics all DOF needs a driver of some kind, in this case the a constant position driver, note that the driver do not deliver any force due to the line.

``````Reaction.Type={Off}
``````

So the driver sets the position, but something else is needed to balance the forces in this direction, in this case this is the balance between pressure which can push it outward and and transversus contraction.

Hope it made it more clear.

Best regards
Søren

Hello Søren,

thank you for your answer. I understand that the driver must be set to determine the system kinematically. Perhaps I have not yet fully understood the principle for applying the abdominal pressure. Here again how I understood it and what my questions are:

1. the buckle segment serves as the attachment point for the abdominal muscles (EO, IO,RA).

2. Five rigid artificial discs form the structure for the transversus muscle.

3. the buckle segment and the disks are controlled by the kinematics of thorax, lumbar spine, and pelvis

4. The abdominal muscles (EO, IO, RA) and the five supporting muscles connect the artificial disks and buckle and are responsible for keeping the buckle segment in balance.

5. the supporting muscles push the artificial disks which activates the transversus muscles to maintain the equilibrium of the buckle
--> How are the supporting muscles activated? Are they present in the normal recruitment process of the muscles? and what forces that really occur in the body should be represented by the supporting muscles?

6. the activated transversus muscles attached to the artificial disks will control the anterior-posterior movement of the artificial segments. I thought that this movement should now be used to determine the radius changes of the respective 5 cylinders and thus, together with the height measurement, to be able to determine the abdominal volume?

AnyKinMeasureLinComb AbdominalVol= {

``````AnyKinMeasure& L1=.Disc1.Disc.VirtuelSegDiscJnt;
AnyKinMeasure& L2=.Disc2.Disc.VirtuelSegDiscJnt;
AnyKinMeasure& L3=.Disc3.Disc.VirtuelSegDiscJnt;
AnyKinMeasure& L4=.Disc4.Disc.VirtuelSegDiscJnt;
AnyKinMeasure& L5=.Disc5.Disc.VirtuelSegDiscJnt;

AnyKinPLine &ref7=.JointsAndDrivers.H;
``````

However, since the measurement of L1-L5 is fixed by the driver, does it not affect a change in abdominal volume that it remains constant during the total movement? Or are these measures only integrated to finally apply the abdominal pressure for the AbdominalPressutreMuscle1?

Basically, I would like to use the abdominal pressure to identify the load in the direction of the pelvic floor.

I hope you understand what I currently have problems understanding.

Kind regards

Nikolas

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