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Brownjohn James (assoc Prof)
09-19-2002, 07:20 PM
Here is a summary of responses to my original request for information.
Many thanks to all who replied and even sent me time series. I'm told it
is customary to post a set of the replies
So I guess I have implicit permission to post these. Trust that's OK.


James brownjohn

Original post:

I'm a civil engineering researcher studying forces induced by
people moving on structures.

Forces due to people on structures are normally modelled as a
sequence of Fourier components obtained from a
sigle footfall trace on a force plate, and this is usually for
vertical forces only.

I have been using a Kistler Gaitway machine to measure 1-miute
series of walking at various speeds to
t study variability of the various parameters i.e. to get more
realistic data.

I am probably not the first to do this so if anyone has studied
this from apoint of view of the forces
generated by the person rather than the forces on the person,
I'd be interested to contact them.

Also the lateral forces are rather harder to measure; a force
plate can only capture one trace and there are
dfficulties using a Gaitway machine for lateral measurements
(according to Kistler and the posts I''ve read).

There are also in-sole pressure measuring devices that people
have used. Again, if anyone has time series data
For lateral/vertical forces in continuous walking I'd love to
hear from them.

Responses:

Dr Brownjohn,

we use a tri-axial force transducer (force and moment) mounted in the
pylon of an artificial leg. From this we can get about 20 seconds of
continuous data. The duration is limited by the length or our cable.
I'm guessing that your colleagues in Singapore may have similar measuing
capability. The walking profile of many below-knee amputees is not that
far off 'normal' people. However, keep in mind that we are not able to
transform the forces to a global coordinate system, since we do not know
the orientation of the leg at all times.

Might I suggest combining an accelerometer mounted on the sacrum with
your present measurements [not that I have tried it, or know anybody who
has]. The shock absorbing capabilities of the body outside the saggital
plane (forward + vertical direction) are not as great. Thus you may get
a reasonable first order estimate of the frequency components.
-- Santosh --

Santosh Zachariah
Research Assistant Professor, Dept. of Bioengineering Prosthetic
Engineering Laboratory

Good luck

........

Dr. Brownjohn;
I'm a podiatrist from Indiana in the U.S.. I use f-scan in shoe pressure
analysis for gait analysis for postural problems. I analyze the force vs
time curves, use a Timing Analysis Module for f-scan and watch the
recordings for changes in Center of Pressure. I have a Power Point
Presentation that explains some of what it is that I do. I'd be happy to
share that with you if you are interested.
What I do primarily, is to modify a temporary orthotic to take
assymetrical function in the feet, and make the function symmetrical.
What ends up happening is that many postural symptoms will improve or
disappear w/ the improvement of symmetry.
sincerely;
Bruce E. Williams, D.P.M.
uwalk4me@attbi.com


........

hello
i'm a french Phd. We use in our lab a new treadmill ergometers (ADAL
treadmill), wich was abble to measure ground reaction forces in three
dimension during gait . It was exactly what you search...
you can be interested by the site http://www.hef.fr
Sincerely
arnaud FAIVRE
Phd
Laboratory of sport science
place st jacque
25000 besancon
FRANCE

........

Prof. Brownjohn, Lateral forces (and anterior-posterior forces) in
continuous walking can and have been measured. Rodger Kram and his
graduate students built a force-measuring treadmill that can measure
all three components of force as well as moments. He is currently at
Colorado State Univ. in Boulder. I am attaching a PDF of the article
on the device.

best,

Young-Hui Chang


.......

Jenny:

Can you please email Dr Brownjohn a
representative dataset for >60 seconds
continuous walking? (Include vertical,
antero/posterior and medio/lateral forces.)

Regards, Brian

Dr. Brownjohn,

Here is the continuous walking data that you have requested it was
collected at 120Hz for 60seconds on a normal subject at a speed of 3.1
km/hr. It has been put in excel format. If you have any questions
please feel free to contact me.

Regards,

Jennifer Kuznicki
Lerner Research Institute
The Cleveland Clinic Foundation
kuznickj@bme.ri.ccf.org
216-445-3236

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