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jverrel84
04-01-2007, 11:39 PM
Dear all,

using a VICON system I would like to measure precise 3D kinematics of upper
extremity movements (arms + shoulder girdle).

Two main approaches seem to exist:
1) register 6 DoF rigid body motion (position + orientation) for each body
segment, by means of at least 3 markers per limb
2) place markers close to the joints - these are shared between the segments
and provide (rough) info on joint center locations. The latter are
calculated from appropriate anthropometric data (e.g. wrist width). Only few
addtional markers seem then to be sufficient for accurate measurement of
full 3D kinematics.

1) is likely the more accurate method; in contrast, 2) requires less markers
and thereby seems to be simpler to apply. The VICON system comes with
pre-defined models for 2).

I'd be grateful for comments on the question which kind of model to use, in
particular
- how much precision is lost (if any) in type-2 versus type-1 models
- regarding type-1: where and how to attach the markers

Further suggestions and literature references are welcome as well.

Best regards,
Julius Verrel


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Julius Verrel (PhD student)
Center for Lifespan Psychology
MPI for Human Development
Lentzeallee 94
D-14195 Berlin
+49 30 82406-410