weight on a platform

[certs]

i have a flat rectangular platform with a load cell at each corner. I used that to calculate the weight of an object sitting on top of the platform. I can do that easily. The platform can be angled, how do I calculate the weight of the object now. How do I account for the angled platform. Thanks.

 

[clun]

Reading of platform x cos(platform inclining angle) = total downward force.
When the platform was in horizontal, the angle = cos90 = 1. So just add up all the load cell reading is fine.


If I was wrong, please let me know.

 

[quark]

In either case the force due to weight acts downwards and is equidistributed to the four legs. (if the weight is not sliding down)

Regards,

 

[MintJulep]

The weight will not be equally distributed, but will always be the sum of the four. I(t can't be anything else, other wise the platform would accelerate.

 

[ccw]

Hi Certs,
Just to complicate things a little more. Many load cells have cross coupling sensitivity, that is, they are sensitive to side loads. So, it is important to know if the vertical axis of the load cells are tilted out of plumb with the table when the table is tilted. If the contact between the top of the cells and the bottom of the table is a ball joint, free to rotate, and the vertical axis of the load cells remain plumb even though the table is tilted, then the above arguments are valid, otherwise, not.

For the load cells plumb case, think of it as two people carrying a piano up a flight of stairs. The person on the bottom bears most of the weight, but both people bear the sum total weight of the piano.

 

[MintJulep]

An interesting sort-or related discussion occured here:

thread404-63321