Dave Cartman wrote:
In article ,
downhill wrote:


I'm kidding, that looks super cool. In order to get "accurate" G
force information do you think it matters where and how you affix
to your body?

Yes it matters, in the karts we get a higher g-force reading when the
accelerometer is placed under the faring verses the on the floor.
The recommended place is in the center of gravity and lowest in the
car as possible. One car I run the logging unit with the axis swapped
because in that formula car it interferes with him sitting. In the
software setup I swap the x and y axis. Since you build track maps
based on speed and lateral g-force it looks pretty funny when it
shows a curve on a straight section of the track or braking after a
turn. Spend much of my times chasing variable names as the two major
data acquisition suppliers Pi & motec are from UK and DownUnder are
very creative in the choice of variable names.

In the context of G force accuracy the amount of knowledge gleamed
from the process depends on your method of analysis, if you just
look for big numbers you might be disappointed seems often that
trends become more useful. Or it could turn out all crap because it
is a 3 axis accelerometer and in most automobile cases the z axis is
not present to any degree, but in ski racing the z axis is very
present and a component of your speed

I don't pretend to know anything about this, but I wonder how much the
skilled skier would "dampen" (and I use the word "dampen" casually)
the forces in the upper body vs at the ski.

Substantially. But the G forces at the ski are somewhat meaningless. What really
matters is the G force of the center of mass of the skier and all his gear. The
extreme G's as the skies bounce over rough texture don't significantly affect
the directional changes of the skier as they average out over time.