Page 74 - Lehrbuch Neigungsmessung deutsch 2018.indd

COMPENDIUM INCLINATION MEASUREMENT
WYLER AG, WINTERTHUR / SWITZERLAND

CORRECTION OF CLOSURE ERROR ACCORDING TO PHILIPS

The goal of the correction of the closure error according to PHILIPS is the determination and the correc-
tion of the deviation in height at all the intersections of all the lines other than the reference lines.
Procedure:
The starting point for the corrective actions is the intersection, of the two reference lines and working
its way out to the borders. At every intersection the height difference between the longitudinal and the
transversal line is eliminated by lowering the upper line and lifting the lower line by the same value. The
outbound portion of the same lines will be subject to the same change in elevation at each cross section.
In this way the relation at the outbound cross sections will remain unchanged.
Order of treatment of the various rectangles starting at
A … D (from inside to outside)

For all corrected values, the standard deviation is calculated
and displayed as the index of correction.
Remarks:
• Measurements not done with the required care will lead to excessive corrections, and the index
of correction will be high
• Carefully taken measurements will lead to uniform and minimal corrections and the index of cor-
rection will be quite low
If the measurement has undergone a correction according to PHILPS, this can be seen when the “Index
of correction” is displayed in the graph.
The definition of the flatness error is calculated in the same manner as described previously. Two virtual
flat parallel surfaces making contact with the measured grid surface at the highest and the lowest points
are turned freely in space until the distance between the two virtual surfaces is the minimum. This distance
is the FLATNESS ERROR ACCORDING TO ISO 1101.

Maximum error of the surface
(Flatness error)

Remarks:
The maximum deviation from a completely flat surface (flatness error) is smaller now. It is also quite
possible that due to the correction of the closure error a new distribution of the contact points with the
virtual surfaces has taken place. In the example above there are now two points on top and two points on
the bottom.
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