Hello,
I am having difficulties applying a moment to simulate the passive extensor
moment of the
torso in the standing model. I applied a positive moment to the Z coordinate
(global ref) L5-
Sacrum joint node using AnyMoment3D. The muscle activities of the inverse
dynamic
analysis show that the muscles are working against the added moment. How can I
apply a
moment that helps the muscles? Am I applying to the wrong point?
Brent
Hello Brent
I have been thinking a bit of your problem. Is it a static or a
dynamic model? As I understand it you are trying to help the muscles
by applying a force. But if the muscle are working against the force
it doesn’t really work, right?
Best regards
Christian, AnyBody Support
— In anyscript@yahoogroups.com, “blulrey” <blulrey@…> wrote:
>
> Hello,
> I am having difficulties applying a moment to simulate the passive
extensor moment of the
> torso in the standing model. I applied a positive moment to the Z
coordinate (global ref) L5-
> Sacrum joint node using AnyMoment3D. The muscle activities of the
inverse dynamic
> analysis show that the muscles are working against the added moment.
How can I apply a
> moment that helps the muscles? Am I applying to the wrong point?
>
> Brent
>
Hello Christian,
I have spent some more time on this and I think I have it figured out. I built
a small test
model so that I could see what was going on.
I have uploaded TestModel.zip with the files. There are 2 segments connected
with a
spherical joint, 4 muscles, and 1 ligament. To make it easy on myself, the
model is
stationary, but I have also tried it while the upper segment is moving.
If the ligament force is set to -5, it creates a moment of -2.5 at the joint.
So by
commenting out the ligament and inserting this:
AnyMoment3D PassiveMoment = {
M = {0, 0, -2.5};
//Mlocal = {0, 0, 0};
AnyRefFrame &Seg1Seg2JntNode =
Main.TestModel.Segments.Segment1.Seg2JntNode;
};
it generates the same muscle forces. However, the reactions are different at
the joint
because there is no ligament force.
So going back to the standing model:
If I apply a moment at the L5-S1 joint node, will it help that joint rotate, and
help the back
muscles that act in the direction of the moment? From the results of my test
model, I
think it will, but please let me know if I’ve misunderstood anything. Also, it
seems that the
muscle activations would be accurate, but the joint reactions may not be.
Thank you,
Brent
— In anyscript@yahoogroups.com, “AnyBody Support” <support@…> wrote:
>
> Hello Brent
>
> I have been thinking a bit of your problem. Is it a static or a
> dynamic model? As I understand it you are trying to help the muscles
> by applying a force. But if the muscle are working against the force
> it doesn’t really work, right?
>
> Best regards
> Christian, AnyBody Support
>
> — In anyscript@yahoogroups.com, “blulrey” <blulrey@> wrote:
> >
> > Hello,
> > I am having difficulties applying a moment to simulate the passive
> extensor moment of the
> > torso in the standing model. I applied a positive moment to the Z
> coordinate (global ref) L5-
> > Sacrum joint node using AnyMoment3D. The muscle activities of the
> inverse dynamic
> > analysis show that the muscles are working against the added moment.
> How can I apply a
> > moment that helps the muscles? Am I applying to the wrong point?
> >
> > Brent
> >
>
Hi Brent
Good explaining model you made there. Well I believe you understand it
correct. Was it the standing model you worked on? The only thing I can
think of is that the model wants to keep a certain posture and there
fore the muscles are working against you moment? If this is not the
case could you maybe upload the model?
Best regards
Christian, AnyBody Support
— In anyscript@yahoogroups.com, “blulrey” <blulrey@…> wrote:
>
> Hello Christian,
> I have spent some more time on this and I think I have it figured
out. I built a small test
> model so that I could see what was going on.
>
> I have uploaded TestModel.zip with the files. There are 2 segments
connected with a
> spherical joint, 4 muscles, and 1 ligament. To make it easy on
myself, the model is
> stationary, but I have also tried it while the upper segment is moving.
>
> If the ligament force is set to -5, it creates a moment of -2.5 at
the joint. So by
> commenting out the ligament and inserting this:
>
> AnyMoment3D PassiveMoment = {
> M = {0, 0, -2.5};
> //Mlocal = {0, 0, 0};
> AnyRefFrame &Seg1Seg2JntNode =
Main.TestModel.Segments.Segment1.Seg2JntNode;
> };
>
> it generates the same muscle forces. However, the reactions are
different at the joint
> because there is no ligament force.
>
> So going back to the standing model:
> If I apply a moment at the L5-S1 joint node, will it help that joint
rotate, and help the back
> muscles that act in the direction of the moment? From the results
of my test model, I
> think it will, but please let me know if I’ve misunderstood
anything. Also, it seems that the
> muscle activations would be accurate, but the joint reactions may
not be.
>
> Thank you,
> Brent
>
> — In anyscript@yahoogroups.com, “AnyBody Support” <support@> wrote:
> >
> > Hello Brent
> >
> > I have been thinking a bit of your problem. Is it a static or a
> > dynamic model? As I understand it you are trying to help the muscles
> > by applying a force. But if the muscle are working against the force
> > it doesn’t really work, right?
> >
> > Best regards
> > Christian, AnyBody Support
> >
> > — In anyscript@yahoogroups.com, “blulrey” <blulrey@> wrote:
> > >
> > > Hello,
> > > I am having difficulties applying a moment to simulate the passive
> > extensor moment of the
> > > torso in the standing model. I applied a positive moment to the Z
> > coordinate (global ref) L5-
> > > Sacrum joint node using AnyMoment3D. The muscle activities of the
> > inverse dynamic
> > > analysis show that the muscles are working against the added moment.
> > How can I apply a
> > > moment that helps the muscles? Am I applying to the wrong point?
> > >
> > > Brent
> > >
> >
>
Christian,
That may be what is happening. I have uploaded StandingModel_Copy.zip. I added
a
moment to the L5-S1 joint (just below the body models in Main). With the moment
active,
the max muscle activity is around 0.96, but without the moment, the max muscle
activity
is around 0.68. The moment should make the muscle activity lower since it is
helping the
thorax extension.
Perhaps I need to simulate a passive moment with a different method?
Brent
— In anyscript@yahoogroups.com, “AnyBody Support” <support@…> wrote:
>
> Hi Brent
>
> Good explaining model you made there. Well I believe you understand it
> correct. Was it the standing model you worked on? The only thing I can
> think of is that the model wants to keep a certain posture and there
> fore the muscles are working against you moment? If this is not the
> case could you maybe upload the model?
>
> Best regards
> Christian, AnyBody Support
>
>
> — In anyscript@yahoogroups.com, “blulrey” <blulrey@> wrote:
> >
> > Hello Christian,
> > I have spent some more time on this and I think I have it figured
> out. I built a small test
> > model so that I could see what was going on.
> >
> > I have uploaded TestModel.zip with the files. There are 2 segments
> connected with a
> > spherical joint, 4 muscles, and 1 ligament. To make it easy on
> myself, the model is
> > stationary, but I have also tried it while the upper segment is moving.
> >
> > If the ligament force is set to -5, it creates a moment of -2.5 at
> the joint. So by
> > commenting out the ligament and inserting this:
> >
> > AnyMoment3D PassiveMoment = {
> > M = {0, 0, -2.5};
> > //Mlocal = {0, 0, 0};
> > AnyRefFrame &Seg1Seg2JntNode =
> Main.TestModel.Segments.Segment1.Seg2JntNode;
> > };
> >
> > it generates the same muscle forces. However, the reactions are
> different at the joint
> > because there is no ligament force.
> >
> > So going back to the standing model:
> > If I apply a moment at the L5-S1 joint node, will it help that joint
> rotate, and help the back
> > muscles that act in the direction of the moment? From the results
> of my test model, I
> > think it will, but please let me know if I’ve misunderstood
> anything. Also, it seems that the
> > muscle activations would be accurate, but the joint reactions may
> not be.
> >
> > Thank you,
> > Brent
> >
> > — In anyscript@yahoogroups.com, “AnyBody Support” <support@> wrote:
> > >
> > > Hello Brent
> > >
> > > I have been thinking a bit of your problem. Is it a static or a
> > > dynamic model? As I understand it you are trying to help the muscles
> > > by applying a force. But if the muscle are working against the force
> > > it doesn’t really work, right?
> > >
> > > Best regards
> > > Christian, AnyBody Support
> > >
> > > — In anyscript@yahoogroups.com, “blulrey” <blulrey@> wrote:
> > > >
> > > > Hello,
> > > > I am having difficulties applying a moment to simulate the passive
> > > extensor moment of the
> > > > torso in the standing model. I applied a positive moment to the Z
> > > coordinate (global ref) L5-
> > > > Sacrum joint node using AnyMoment3D. The muscle activities of the
> > > inverse dynamic
> > > > analysis show that the muscles are working against the added moment.
> > > How can I apply a
> > > > moment that helps the muscles? Am I applying to the wrong point?
> > > >
> > > > Brent
> > > >
> > >
> >
>
Hi Brent
I have been looking at your model, I can see there must be something
wrong. I haven’t figured out what it is yet… but I am still looking
at it. Please update me if you make any progress.
Best regards
Christian, AnyBody Support
— In anyscript@yahoogroups.com, “blulrey” <blulrey@…> wrote:
>
> Christian,
> That may be what is happening. I have uploaded
StandingModel_Copy.zip. I added a
> moment to the L5-S1 joint (just below the body models in Main).
With the moment active,
> the max muscle activity is around 0.96, but without the moment, the
max muscle activity
> is around 0.68. The moment should make the muscle activity lower
since it is helping the
> thorax extension.
>
> Perhaps I need to simulate a passive moment with a different method?
>
> Brent
>
> — In anyscript@yahoogroups.com, “AnyBody Support” <support@> wrote:
> >
> > Hi Brent
> >
> > Good explaining model you made there. Well I believe you understand it
> > correct. Was it the standing model you worked on? The only thing I can
> > think of is that the model wants to keep a certain posture and there
> > fore the muscles are working against you moment? If this is not the
> > case could you maybe upload the model?
> >
> > Best regards
> > Christian, AnyBody Support
> >
> >
> > — In anyscript@yahoogroups.com, “blulrey” <blulrey@> wrote:
> > >
> > > Hello Christian,
> > > I have spent some more time on this and I think I have it figured
> > out. I built a small test
> > > model so that I could see what was going on.
> > >
> > > I have uploaded TestModel.zip with the files. There are 2 segments
> > connected with a
> > > spherical joint, 4 muscles, and 1 ligament. To make it easy on
> > myself, the model is
> > > stationary, but I have also tried it while the upper segment is
moving.
> > >
> > > If the ligament force is set to -5, it creates a moment of -2.5 at
> > the joint. So by
> > > commenting out the ligament and inserting this:
> > >
> > > AnyMoment3D PassiveMoment = {
> > > M = {0, 0, -2.5};
> > > //Mlocal = {0, 0, 0};
> > > AnyRefFrame &Seg1Seg2JntNode =
> > Main.TestModel.Segments.Segment1.Seg2JntNode;
> > > };
> > >
> > > it generates the same muscle forces. However, the reactions are
> > different at the joint
> > > because there is no ligament force.
> > >
> > > So going back to the standing model:
> > > If I apply a moment at the L5-S1 joint node, will it help that joint
> > rotate, and help the back
> > > muscles that act in the direction of the moment? From the results
> > of my test model, I
> > > think it will, but please let me know if I’ve misunderstood
> > anything. Also, it seems that the
> > > muscle activations would be accurate, but the joint reactions may
> > not be.
> > >
> > > Thank you,
> > > Brent
> > >
> > > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
wrote:
> > > >
> > > > Hello Brent
> > > >
> > > > I have been thinking a bit of your problem. Is it a static or a
> > > > dynamic model? As I understand it you are trying to help the
muscles
> > > > by applying a force. But if the muscle are working against the
force
> > > > it doesn’t really work, right?
> > > >
> > > > Best regards
> > > > Christian, AnyBody Support
> > > >
> > > > — In anyscript@yahoogroups.com, “blulrey” <blulrey@> wrote:
> > > > >
> > > > > Hello,
> > > > > I am having difficulties applying a moment to simulate the
passive
> > > > extensor moment of the
> > > > > torso in the standing model. I applied a positive moment to
the Z
> > > > coordinate (global ref) L5-
> > > > > Sacrum joint node using AnyMoment3D. The muscle activities
of the
> > > > inverse dynamic
> > > > > analysis show that the muscles are working against the added
moment.
> > > > How can I apply a
> > > > > moment that helps the muscles? Am I applying to the wrong
point?
> > > > >
> > > > > Brent
> > > > >
> > > >
> > >
> >
>
Hi Christian,
I added moments at all the other lumbar joints, and it seems to be working as
expected:
with a lower max muscle activity with the help of the applied moments. I think
that only
one moment at L5-S1 is not close enough to what the body is really doing. (The
new files
are in the same zip file.)
Brent
— In anyscript@yahoogroups.com, “AnyBody Support” <support@…> wrote:
>
> Hi Brent
>
> I have been looking at your model, I can see there must be something
> wrong. I haven’t figured out what it is yet… but I am still looking
> at it. Please update me if you make any progress.
>
> Best regards
> Christian, AnyBody Support
>
> — In anyscript@yahoogroups.com, “blulrey” <blulrey@> wrote:
> >
> > Christian,
> > That may be what is happening. I have uploaded
> StandingModel_Copy.zip. I added a
> > moment to the L5-S1 joint (just below the body models in Main).
> With the moment active,
> > the max muscle activity is around 0.96, but without the moment, the
> max muscle activity
> > is around 0.68. The moment should make the muscle activity lower
> since it is helping the
> > thorax extension.
> >
> > Perhaps I need to simulate a passive moment with a different method?
> >
> > Brent
> >
> > — In anyscript@yahoogroups.com, “AnyBody Support” <support@> wrote:
> > >
> > > Hi Brent
> > >
> > > Good explaining model you made there. Well I believe you understand it
> > > correct. Was it the standing model you worked on? The only thing I can
> > > think of is that the model wants to keep a certain posture and there
> > > fore the muscles are working against you moment? If this is not the
> > > case could you maybe upload the model?
> > >
> > > Best regards
> > > Christian, AnyBody Support
> > >
> > >
> > > — In anyscript@yahoogroups.com, “blulrey” <blulrey@> wrote:
> > > >
> > > > Hello Christian,
> > > > I have spent some more time on this and I think I have it figured
> > > out. I built a small test
> > > > model so that I could see what was going on.
> > > >
> > > > I have uploaded TestModel.zip with the files. There are 2 segments
> > > connected with a
> > > > spherical joint, 4 muscles, and 1 ligament. To make it easy on
> > > myself, the model is
> > > > stationary, but I have also tried it while the upper segment is
> moving.
> > > >
> > > > If the ligament force is set to -5, it creates a moment of -2.5 at
> > > the joint. So by
> > > > commenting out the ligament and inserting this:
> > > >
> > > > AnyMoment3D PassiveMoment = {
> > > > M = {0, 0, -2.5};
> > > > //Mlocal = {0, 0, 0};
> > > > AnyRefFrame &Seg1Seg2JntNode =
> > > Main.TestModel.Segments.Segment1.Seg2JntNode;
> > > > };
> > > >
> > > > it generates the same muscle forces. However, the reactions are
> > > different at the joint
> > > > because there is no ligament force.
> > > >
> > > > So going back to the standing model:
> > > > If I apply a moment at the L5-S1 joint node, will it help that joint
> > > rotate, and help the back
> > > > muscles that act in the direction of the moment? From the results
> > > of my test model, I
> > > > think it will, but please let me know if I’ve misunderstood
> > > anything. Also, it seems that the
> > > > muscle activations would be accurate, but the joint reactions may
> > > not be.
> > > >
> > > > Thank you,
> > > > Brent
> > > >
> > > > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
> wrote:
> > > > >
> > > > > Hello Brent
> > > > >
> > > > > I have been thinking a bit of your problem. Is it a static or a
> > > > > dynamic model? As I understand it you are trying to help the
> muscles
> > > > > by applying a force. But if the muscle are working against the
> force
> > > > > it doesn’t really work, right?
> > > > >
> > > > > Best regards
> > > > > Christian, AnyBody Support
> > > > >
> > > > > — In anyscript@yahoogroups.com, “blulrey” <blulrey@> wrote:
> > > > > >
> > > > > > Hello,
> > > > > > I am having difficulties applying a moment to simulate the
> passive
> > > > > extensor moment of the
> > > > > > torso in the standing model. I applied a positive moment to
> the Z
> > > > > coordinate (global ref) L5-
> > > > > > Sacrum joint node using AnyMoment3D. The muscle activities
> of the
> > > > > inverse dynamic
> > > > > > analysis show that the muscles are working against the added
> moment.
> > > > > How can I apply a
> > > > > > moment that helps the muscles? Am I applying to the wrong
> point?
> > > > > >
> > > > > > Brent
> > > > > >
> > > > >
> > > >
> > >
> >
>