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Pierre Baudin
08-27-1996, 02:15 AM
Forwarded From: Alain Lajoie
Subject: Goniometer

Bonjour Pierre, pourrais-tu soumettre ce courrier au groupe de discussion
Biomech-l

Since I work in the ergonomic field, I think there's is not enough
importance given to the impact of the equipment (mesuring tools) use to
measure working performance on the natural mobility of the subject.

One application problem I see when I look at Marras trunk goniometer is that it
can only be use in laboratories. The cases in the back are quite large and the
harness big. I never got the chance to see it in person but it seems also to
take some space in the back (can't sit down or be close to a wall). This can
generate problems if you'd want to use it in working situation (I know it
wasn't develope for that...)

I think there is a great need in developping tools that can be use in
working situation. The goniometer use by Marras was made from several
potentiometers that mesured one axis each. This make the hardware quite
voluminous.

I was wondering if anyone ever heard about a spherical potentiometer wich
would work like a ball joint. One rod with an spherical shape at the
extremity wich is encased in a just over 1/2 sphere.

The way I think it would calculate the position is by a point representing the
end of the rod. This point would make and electrical contact on the inner
surface of the outer sphere. The contact point with the center of the sphere
would make a line wich coud be position in a three dimensional models. From
this line, horizontal, vertical and lateral coordinates could be calculated.

>From my point of view, this kind of potentiometer would pose great
advantages to the mobility when worn. Ball joint system offer pratticly no
resistance and offer all movement needed.

Any suggestion would be appreciated. We're about to start a project and the
object would be to develope a trunck goniometer that can use in working
condition. But from what has been made and the existing potentiometer, there
seems to be no solution. The only way I see it, is to develope something
different. A spherical potentiomer seems a good one...

but can it be made??? Is my idea way out of line?

Before you answer me, please take note that I have no formation in
engineering, only in ergonomics. I writing this only to share your point of
view from this idea.

Please, be constructive in your answers! (and pardon my english, I'm french)
,,,,,
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Alain Lajoie Tel: 987 4758
CINBIOSE Fax: 987 6183
Universite du Quebec a Montreal Adresse: lajoie.alain@uqam.ca
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