View Full Version : Mechanical work with force platform

05-12-2004, 01:57 AM
Hi everybody,
I am working with 2 large force platforms Kistler, they cover the entire
living area on the ground inside 2 indirect calorimeter rooms.
I want to calculate the energy expenditure due to physical activity of a
human being, living "normally" in this kind of room. I would like to get
some advice or informations from someone who would have already calculated
mechanical work with a force platform.
My reasoning is the following : I collect forces in the three directions
Fx, Fy, Fz (50Hz), so I can get accelerations, ax, ay, az (F=m.a) and then
by integrating Iget the corresponding speeds of the center of mass Vx, Vy,
Vz. T T t
The definition of the work could be the following : W=[ F(t).V(t).dt = [
F(t).{Vo+[a(t').dt' }.dt ; Vo can be forced to zero. T=1 min.
0 0
So my algorithm starts with the integration of the accelerations to get the
speeds at each sample, then I integrate the product F.V on each 1 minute
intervals to get a result in J/min.
Do you think this is correct ? Is there any trap to avoid (because there
are distorsions in the speed curves, and my values of mechanical work seems
to be low, always less than #4kJ/min) ?

Thanks for sharing your background.

__________________________________________________ _____________
Vincent GIGOT
European Centre of Taste Sciences
15 rue Hugues Picardet
21000 DIJON
tel.: +33 (0)3 80 68 16 61 (work)
+33 (0)6 32 41 18 94 (mobile)
fax.: +33 (0)3 80 68 16 21
__________________________________________________ _____________

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