![background image](http://html.mh-extra.com/html/sick/lms4000/lms4000_operating-instructions-manual_1263986021.webp)
The maximum range is set to 70° by default. This produces 841 measurement points.
The range can be restricted by increasing the start angle (default setting = 55°) or
reducing the stop angle (default = 125°). Please note that the angle beam is defined
orthogonally in relation to the front at 90° and the direction of rotation of the device is
set to clockwise.
The minimum difference between start angle and stop angle is 1/12°; this is equiva‐
lent to the output of a single measurement point. It is not possible to output multiple
scan ranges (e.g., 55° ... 70° and 90° ... 110°).
3.5.7.2
Edge filter
The edge filter prevents incorrect/extreme distance values at edges which result from it
not being possible to determine a distance value for the previous or next point (e.g., if
the previous or next measurement point was too dark or lay outside the measuring
range) or because of incorrect detection due to too little light remission at the object
itself,
see "Impact of object surfaces on the measurement", page 18
. The filter evalu‐
ates the difference in distance between adjacent points.
When the edge filter is activated, the device sets a distance value of 0 at each edge
(values in
bold
in the table).
Table 4: Example: Measured values with and without edge filter
Angle (distance values in mm)
Scan
1
2
3
4
5
6
7
…
1, not filtered
0
750
1145
1150
1147
1500
0
…
1, filtered
0
0
1145
1150
1147
0
0
…
The edge filter enables points to be entirely suppressed at the outer edges of the
object. In this case, the width of an object is detected by up to 2× angular resolution too
narrow.
3.5.7.3
Median filter
This filter is suitable for excluding individual outliers from the calculation of an average
value.
The values included in the calculation are defined using a 1 x 3 matrix:
3 measured values, consisting of the distance values of a point and its two adjacent
points in the scan, are sorted by size.
The measured value in the middle of this sequence is output as the distance value,
along with its remission value and the original angle correction value.
The median values are determined and output as moving values (median angular incre‐
ment 2 from value 1, 2, and 3; median angular increment 3 from value 2, 3, and 4,
etc.).
A median cannot be determined as the measured value for the first and last angular
increments in a scan. The distance value 0 (= invalid) is always output.
Table 5: Example: Median in angular position 2, 3, and 4
Angle (distance values in mm)
Scan
1
2
3
4
5
…
Unfiltered measured values
1
850
852
851
849
850
…
2
849
851
850
853
852
…
3
850
849
853
851
850
…
…
…
…
…
…
…
…
PRODUCT DESCRIPTION
3
8023198//2018-06-18 | SICK
O P E R A T I N G I N S T R U C T I O N S | LMS4000
21
Subject to change without notice