gvcdijon68

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 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

CESG - CNRS

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

http://www.cesg.cnrs.fr/

__________________________________________________ _____________

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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 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

CESG - CNRS

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

http://www.cesg.cnrs.fr/

__________________________________________________ _____________

-----------------------------------------------------------------

To unsubscribe send SIGNOFF BIOMCH-L to LISTSERV@nic.surfnet.nl

For information and archives: http://isb.ri.ccf.org/biomch-l

Please consider posting your message to the Biomch-L Web-based

Discussion Forum: http://movement-analysis.com/biomch_l

-----------------------------------------------------------------