2
Overview
Counting people with the VL53L1X consists of using the multiple zones of the sensor receiving SPAD area,
and of configuring it with two distinct fields of view (FoV), to alternatively get a ranging distance from them
and consequently recognize the movements of a person. Using this method, the number of people occupying a
meeting room, accessible from a reasonably narrow access, is known at all times by detecting the entrances and
exits of the attendees.
By measuring and analyzing the distances of targets within the FoVs of a front and back zone (see figure below
and
Figure 3. Front and back zones
), a simple algorithm can detect the direction a person crosses the area
under the two FoVs. This algorithm "understands" that someone is under one of the FoV as long as the distance
measured by the sensor under this FoV is between 0 and a threshold value specified in mm.
Figure 1.
VL53L1X FoV divided in two subfields of view
From a timing perspective, the sensor alternatively ranges on each of the two zones, for a very short period of
time in milliseconds. It is possible to determine in which direction a person crosses the area, depending in which
order this person has been detected in the two zones, as shown in the figure below.
Figure 2.
Person counting chronogram
UM2600
Overview
UM2600
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Rev 2
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