Face Dipstick 2200 Series, Руководство оператора, Страница: 83 / 107

C
HAPTER
9 - BIAS
9-3
report that it is going “uphill” every step, even though it really is not. The profile
produced by this run will show a pronounced uphill slant because of the artificial tilt.
Of course, you will probably never measure the surface of a beach volleyball court, so the
description above is a gross exaggeration of what really happens when you walk the Dipstick
on pavement. But the principle that is demonstrated in this example is the same as what really
happens on pavement– except that the Bias on pavement is only about 0.001” (0.025 mm) to
0.003” (0.076 mm) per step.
Why can’t we just compensate for that automatically in the software? The reason you can’t do
this is because the amount of Bias varies with the amount of texture and the amount of dust or
grit on the surface. The Bias can be two or more times higher on a rough textured or dirty
surface, and it can be half or less on a smooth, clean surface.
“Moon Feet”
We have conducted experiments with many different types and designs of “feet” for the
Dipstick, to include different configurations and sizes, pointed feet, rounded pointed feet,
different size swivel feet, and different contact surface material. The 2 ½” diameter “Moon”
feet on your Dipstick are designed to minimize the effects of both Surface Roughness Bias and
Bias from grit and dust. These are the best choice for measuring on almost any surface of any
texture.
Start Point
Direction of travel
1 2 3 4 5 6 7
True Profile of Beach Volleyball Court (Sand)
Profile Reported By Dipstick (with Bias)