In response to your recent posting on tracking the head position.

We are a Gait laboratory interested in all segmental movements during
walking. Recently, we have added head postion (tilt, lateral flexion,
and rotation) to our list. We are using a Motion Analysis 3-D
high-speed video system with 6 cameras operating at 60 Hz to capture a
full body set of retro-reflective markers. We use 3 markers arranged
on a baseball cap: one anterior, one top, and one posterior on the
midline of the head. We align the hat so that when the patient is
relaxed and looking forward, the line formed by the anterior and
posterior markers is parallel to floor. We call this neutral position.
We then create a coordinate system from the 3 markers and reference the
orientation of this system to our room system and the local system fixed
to the trunk.

We are using a program called Orthotrak 4.1 (Motion Analysis Corp.),
which automatically performs the above calculations.

Hope this helps,


Patrick W. Castagno
Manager/Biomechanist - Gait Analysis Laboratory
duPont Hospital for Children
1600 Rockland Road
Wilmington, DE 19899

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