Hello Soren,
Thank you for the inputs. As you suggested, I did simple checks.
First, I checked a fixed posture (i.e., 70 degree flexion) without
hand loads. Jointmuscle outputs for the L5/S1 are about 75 Nm. The
values are a bit lower than what I got from 3DSSPP. Yet, they are
acceptable.
Then, I repeated the same model with only one change in the motion
driver. I drove the trunk with measured angles (roughly flexion
angles range from 0 to 70 degree). For simplicity, lateral bending
and axial rotation were set to be 0. Then, Jointmuscle outputs for
the L5/S1 are found to be about 10 Nm.
I applied the same marker dirvers used in Gait3D. So, the reaction
type for marker drivers are set to be “off”.
I am not sure if driving posture with markers could cause this kind
of problem, since it appears that AnyBody gives acceptable values for
the static posture. I think I need more of your advice on this
problem to solve it.
Sincerely,
Sunwook
— In anyscript@yahoogroups.com, “AnyBody Support” <support@…>
wrote:
>
> Hi Sunwook
>
> I am not sure what was the size of you hand load so i can not
judge
> if the moment of 39Nm is ok or not. If the way you have applied the
> forces are correct this moment should be ok, you should not need to
> add extra stuff to read out the moment.
>
> To check your model, you could try expluding your hand loads and
> just add a AnyForce3D to the hands. This will create a constant
> force vector and you will be able to check if the moments of the
> joints are resonable. You may exclude gravity to get a more clear
> picture if needed.
>
> In principle it should be possible to load the hands in the same
way
> as the feet in the Gait3D model.
>
> I hope this helps you move on
>
> Best regards
> S?en, AnyBody Support
>
>
>
>
> — In anyscript@yahoogroups.com, “ninegu_sun” <ninegu_sun@>
> wrote:
> >
> > Thank you for the quick response.
> >
> > I just checked JointMuscles folder to see positive and negative
> > muscle outputs for L5SacrumJnt, using the No_Muscle model.
> > The values appear to be still small (-39 Nm is the max value in
> all
> > DOFs), while compressive forces fall in a reasonable range.
> >
> > Currently, I use the SpineTwoArms\BodyModel_NoMuscles.Any and
> apply
> > external forces on the hands (measured from loadcells).
> >
> > Is it possibly because of external loads applied on the hands? I
> use
> > the same method for applying forceplate forces in Gait3D to apply
> > external forces on the hands.
> >
> > Does this mean that I need to include a seperate folder to
compute
> > L5/S1 moments?
> >
> > Sincerely,
> > Sunwook
> >
> >
> > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
> > wrote:
> > >
> > > Hi Sunwook
> > >
> > > I think the joint you are looking for is the L5Sacrum joint in
> the
> > > model.
> > >
> > > You are correct that joint reactions in the spine are the
> reaction
> > > forces in the three directions, since spherical joints are
being
> > used.
> > >
> > > If you are looking for the moment, you need to use a model
> without
> > the
> > > ordinary muscles on. so choos a bodymodel version
> > > names “_NoMuscles.any”. This model have each dof equipped with
> > moment
> > > generating muscles, and you may read out the monments.
> > >
> > > The reason why we have a SacrumPelvis reaction is because there
> are
> > no
> > > muscles to carry this reaction.
> > >
> > > Please ask again if you have further questions.
> > >
> > > Best regards
> > > S?en, AnyBody Support
> > >
> > >
> > > — In anyscript@yahoogroups.com, “ninegu_sun” <ninegu_sun@>
> wrote:
> > > >
> > > > Dear AnyBody Team,
> > > >
> > > > I’d like to get L5/S1 joint moments from an AnyBody standing
> > model.
> > > > Joint reactions appear to give compressive forces, and there
> is
> > > > Sacrumpelvis reaction folder.
> > > > I though that sacrumpelvis reaction may be equivalent to
L5/S1
> > joint
> > > > moments, yet values from sacrumpelvis reaction seem to be too
> > small.
> > > >
> > > > Is there a simple way to obtain L5/S1 joint moments?
> > > >
> > > > Sincerely,
> > > > Sunwook
> > > >
> > >
> >
>