Applications and Acknowledgements
B6. General Points
-should
foot-line be a fundamental parameter?
-allows for the expression of
step/stride/walking base as a 2D and 3D vector equation.
-“induced
stress” experiments may help in diagnosis
-static analysis of
movements outside points and lines, like lateral knee joint movement and
step-out-line, may be revealing
-the point and line projections must
be purely vertical wrt the plane of interest
-if time profile-some
joint and other rotations give equivalent values in the 2D
-computer
modeling-rigid frame and introduce rotations sequentially
-degrees of
freedom wrt parameter changes
-standard orientation not along
foot-line, but "push-off-line", even though the start and reference foot
models' foot-lines are parallel to the straight line at heel-contact.
-for modeling, show how variations in each fund. parameter affects other
measured distances like, step, stride, etc.
-have to determine how it
fits in, how it can be applied effectively to each area
-the 2D
projection of points other than the minimum 4 may show periodicity with
respect to changes in the primary elements.
-at first, do measure at
heel-strike and heel-point contact, if possible, heel-point not at the bone,
but is contact point with the floor. Any of several choices for heel-point,
but contact with the floor may be best, since that's most easily measurable
without equipment
- for different str in sequential steps, 2 models
at heel-point with the different str values, both in standard orientation,
each the reference for it's appropriate step, heel-points can then be
related like an aberration
-body motions, momentum, etc. have to be
studied to determine effect on parameters
-negative step?, no-no
step, shortened to 0 carry
-there may be some simplifications which
can be applied for quicker analysis, if the required equipment is
unavailable. This would have to be determined.
-there are physical
constraints relevant which may limit the ranges of one or more of the
parameters wrt one or more of the others.
-applied to running - last
heel-point position when rear-foot leaves the ground to the rear-pelvic
joint at the next heel-contact (two snapshots needed per step, step-heel
contact and rear-foot leave ground (ie. the start/stop for aberrations).
- though new, can be immediately applied to all levels of gait analysis
because it can track walking patterns over any period of time, without the
need to compare to standards, since it's only a measurement system. But,
comparison to standards will be important in the full analysis, so a
relevant database would be very useful.
-the orientation of the upper
body greatly confuses the interpretation of direction changes over the path.
But, the upper body pointing "straight ahead" doesn't mean the person is
walking a straight line. And, a person who places each foot on it's
appropriate straight line for every step isn't necessarily walking straight
in each step, and probably usually isn't.
-The lower frame defines
both direction and distance through the varied relationship between the 4
minimum points (and foot-line).
C. Quadrupeds
The biped is the
simplest normal gait system to model. The same general strategy should apply
to quadrupeds, or any multi-ped, but the system is a fair bit more
complicated. Modeling would be much more complicated, but the measurements
very similar.
It may be best to think of the quadruped as two
connected "biped sets". All the parameters would be derived from tracking
the 8 minimum points of quadruped gait, the front and rear would both have
the same minimum 4 points as for biped gait.
The line of connection,
the spine-line, is from the center of the front "shoulder-line" to the
center of the rear pelvis-line. Though this represents the spine, it should
be a straight line connecting the shoulder and pelvis-line centers, and it
may be desirable to define the measures related to this connection as
fundamental parameters.
Spine curvature would be seen as an apparent
rotation of the spine-line, as well as apparent rotation of the shoulder and
/or pelvis-line at the centers, both leading to direction change, as well as
a decrease in apparent spine length.
The development of this
application would be much better using experimental data. It's easy enough
to choose points to track in the 2D plane, but the order of heel-contact may
vary, and organizing the direction relationships more complicated.
Comparison of snapshots at each heel-contact, with identification of the 8
points, as well as the time of each foot contact, will make it much easier
to determine the proper procedure for application. But, it's still just
tracking points in 2D. Each snapshot is a reference grid, and how the
various lines and angles are related to overall gait, within each step and
over sequential snapshots, requires consideration of what factors are
considered important for that study, and what generalizations, standard
positions and/or values are desired or available.
The establishment
of the 2 “standard start positions” should be similar to biped, but there
would be many more “straight lines over the step”, representing sequential
direction changes.
This would be a very challenging area of research
at the beginning. Once standard procedures are established, though, it
should be as easily applied as for biped gait.
D. Acknowledgements
Very many
thanks to Walter Muma, Jean Hurrle and Gammon Earhart for their
contributions to this effort. Jean and Gammon for very productive
discussions to focus and clarify the work on the trapper and clinical sides,
resp, and Walter for putting up with a lot to publish the article and
revisions on his Wildwood Survival web-site.
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© 2008
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