Thanks for the answer.
-
I’ll try to work with that*…
-
I cannot create new nodes on the segment because I do not know the
position of the segment. It poses the exact same problem… How can I place a
node on a segment for which I do not know the orientation?
*I could possibly overlap the reference systems using the KitVaughan markers
file, but unfortunately, it looks like the Metatarsal marker isn`t the 5th
metatarsal (looking at the model view). Is it?
Thanks again,
Jean-Olivier
From: anyscript@yahoogroups.com [mailto:anyscript@yahoogroups.com] On Behalf
Of AnyBody Support
Sent: Tuesday, June 19, 2007 6:16 PM
To: anyscript@yahoogroups.com
Subject: [AnyScript] Re: Segment orientations
Hi Jean-Olivier
I am not so sure about these rules for the legs, unfortunately. I
know that the x axis of the foot is parrallel to the footsole and
that the center of mass for the foot is defined according to
Winters.
If you look in the Leg3d/interface.any you will see some rotational
measures. If you prefer to use a specific set of definitions this
is the location to create them. If you create new nodes of the
segments that has the right locations and orientations you can
create your own rotational measures that can co-exist with the
original ones. In this way you would be sure about the definitions.
Best regards
Søren, AnyBody Support
— In HYPERLINK
"mailto:anyscript%40yahoogroups.com"anyscript@yahoogroups.com, Jean-Olivier
Racine <jean-
olivier.racine.1@…> wrote:
>
> Hello Søren,
>
>
>
> I’ll try to explain it better with an example:
>
>
>
> - Winter (table 6.3, p. 63) defines the foot segment’s
longitudinal
> axis as the line formed by connecting the second metatarsal with
the lateral
> malleolus, located at this last landmark.
>
> - Vaughan (fig. 3.6, p. 25) defines the foot longitudinal
axis as
> being a line formed by connecting the heel with the fifth
metatarsal, again,
> located at the malleolus.
>
>
>
> Choosing any of these two definitions gives very different results
because
> anybody defines the ankle as an universal joint that rotates
around the
> common z and y axis of both reference systems. The flexion-
extension angle
> is offset by almost 30 degree and tilted by at least 15. Same
(opposite)
> goes for the abduction-adduction angle. Therefore, if I specify a
> flexion-extension angle to a driver that drives the ankle, I have
no clue
> what 30 degrees means, unless I know the exact local reference
system
> definitions of both the foot and shank.
>
>
>
> What rules were used to defined the local reference systems of the
foot,
> shank, thigh and pelvis?
>
>
>
> Jean-Olivier
>
>
>
>
>
> From: HYPERLINK
"mailto:anyscript%40yahoogroups.com"anyscript@yahoogroups.com
[mailto:HYPERLINK
"mailto:anyscript%40yahoogroups.com"anyscript@yahoogroups.com]
On Behalf
> Of AnyBody Support
> Sent: Sunday, June 17, 2007 7:03 AM
> To: HYPERLINK
"mailto:anyscript%40yahoogroups.com"anyscript@yahoogroups.com
> Subject: [AnyScript] Re: Segment orientations
>
>
>
> Hi Jean-Olivier
>
> If you want the segment axes displayed you can add
> an “AnyDrawRefFrame” in the segments of the leg, this will display
> the segment axis orientations. For the leg this can be done in the
> file Leg3d/Seg.any
>
> Please ask again if this do not answer your questions.
>
> Best regards
> Søren, AnyBody Support
>
> — In HYPERLINK
"mailto:anyscript%40yahoogroups.com"anyscript@yahoogroups.com
<mailto:anyscript%
40yahoogroups.com> ,
> Jean-Olivier Racine <jean-
> olivier.racine.1@> wrote:
> >
> > Hi there,
> >
> >
> >
> > In my model, I would like to constraint my kinematics using
segment
> > orientation. Basically, I would specify the tridimensional
> orientation of
> > all segments using quaternions. To do so, I need to be able to
> know how the
> > current segment axis have been chosen, so I can superpose both
> reference
> > systems. I know that currently the origins of the segments axis
> are the
> > center of mass, but how are the longitudinal, transverse and
> > antero-posterior axis of the pelvis, shank, thigh and foot
defined?
> >
> >
> >
> > Known data:
> >
> > Shank longitudinal: KneeJoint -> AnkleJoint
> >
> >
> >
> > Jean-Olivier
> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
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