Tech Briefs Magazine - June 2022 - Sensor-13

gorithm provides updated people-count
and location data within 1.5 seconds after
an individual moves into a zone defined
by the user during commissioning.
After detecting an individual, the algorithm
needs only 113 ms to provide updated
count and location data.
The DSP uses its universal asynchronous
receiver-transmitter (UART) port
in push mode to transmit occupancy
metadata. Transmitted in JSON format,
this metadata packet includes
occupancy state (occupied or vacant),
people-count, people-location as (x,
y) coordinates, along with other data
(Table 1).
Downstream of the DSP subsystem,
the ADuCM4050 MCU subsystem runs
in the AWS FreeRTOS environment,
supporting the high-level EagleEye application
and connectivity services required
for sensor commissioning and
communication with Analog Devices'
associated cloud-based service.
A set of integrated power management
features including multiple power
modes and clock gating capabilities
enable the device to achieve low power
execution. As a result, the MCU requires
only 41 microamps per megahertz (μA/
MHz) (typical) in active mode and
0.65 μA (typical) in hibernation mode.
During inactive periods, the processor
consumes only 0.20 μA (typical) in its
fast-wake-up shutdown mode, or only 50
nA in full shutdown mode.
How to Quickly Begin People-Counting
In the trial kit, Analog Devices combines
the DSP and MCU subsystems with
a camera sensor, a lens, LEDs, and buttons
in a compact package.
Developers can quickly deploy people-counting
by simply mounting the
sensor unit in a room or indoor space,
directly above a region of interest. The
sensor can use power from a variety of
sources. Users can run a wire to the
unit's DC connector to supply a 5.5 to 36
volt DC source, or power it by supplying
a USB power source using a micro USB
cable, or active USB extension for distances
beyond one meter.
After mounting the sensor unit, users
can visually confirm the sensor positioning
and desired field of view (FOV)
using the companion EagleEye PeopleCount
app (Figure 2).
Sensor Technology, June 2022
After users verify the sensor FOV, they
proceed with the brief device commissioning
process. During commissioning
and later during operation, users can observe
the DSP and MCU LEDs built into
the sensor unit to monitor the current
status of the respective subsystems.
The app walks users through the few
steps required for sensor commissioning.
In this process, users indicate which
areas the algorithm should monitor
within the FOV by marking a series of
inclusive masks, such as the floor mask
(Figure 3, left). Areas to exclude are just
as important for accurate counts. During
the commissioning process, the companion
app allows users to specify different
exclusion masks, for example, windows
and display screens (Figure 3, right).
Once mounted and commissioned,
the sensor unit begins transmitting its
metadata to Analog Devices' cloud. By
logging into the cloud using credentials
provided during registration, users can
examine a series of graphical representations
of occupancy.
The platform can be embedded in
custom designs built with the appropriate
Blackfin processor and suitable
external flash memory. Analog Devices
also makes the EagleEye software package
available for registered trial kit customers.
What
Can Be Done with Occupancy Data?
Once building occupancy sensors are
set up, the data can be used in many
ways:
* During this pandemic age, the data can
be used to see if proper social distancing
is being observed with the " People
ID with Properties " metadata output
listed in Table 1.
* If the EagleEye detects that a room is
occupied, the data can be used by a
smart building system to ensure that
the HVAC environmental settings are
appropriate for the number of people
in the room and that there is proper
lighting.
* If the EagleEye detects that a room is
unoccupied, the data can be used by a
smart building system to set the HVAC
environmental settings accordingly
and turn off the lights.
* If a building evacuation is necessary
due to a fire or some other emergency,
the occupancy sensor could alert
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the proper personnel through a smart
building system that the building is still
occupied and the location of the occupants.
Conclusion
As
companies pay the price of significant
building energy consumption from
office lighting, heating, and cooling, effective
resource management of often
vacant office spaces is driving a need for
more accurate occupancy data. Based
on a proprietary algorithm running on
a low-power digital signal processor, the
Analog
Devices ADSW4000KTZ Trial
Kit provides a comprehensive sensorto-cloud
platform for evaluating and
deploying the real-time occupancy monitoring
with room-level data needed for
more effective building energy management.
This
article was written by Rich Miron,
Sr. Technical Content Developer, Digi-Key
Electronics. For more information, contact
Mr. Miron at rich.miron@digikey.com or visit
http://info.hotims.com/82322-161.
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