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XK10 Hardware
XK10 Software
Flatness
Level
Appendix B: Filtering
Filtering vs averaging
XK10 uses a median filter instead of averaging. The reason for this is that
median filters are better suited to smooth sudden fluctuations caused by air
turbulence and random vibrations.
With averaging, when data is captured (for example, 4 second averaging) the
average of all data points over a 4 second period is returned; this means that
noisy data is also included in the result. However, with a median filter, noisy
data points are replaced with the median data point within the sample.
NOTE: Median filtering is part of the reason you may get different straightness
results when compared to laser interferometers.
XK10 alignment laser system
XK10 Applications
Straightness
Parallelism
Coaxiality
Squareness
Spindle direction
Median Averaging
10
8
6
4
2
0
-2
-4
-6
0
5
Straightness data capture
25
20
15
10
5
0
-5
0
1
2
Raw Data
10
15
Time
Bad data point
Averaging result: 2.6
Median result: 0.5
3
4
5
6
7
8
Sample number
www.renishaw.com/xk10
Median Filter
20
25
9
10
11
153
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