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How Radar Sensors Significantly Improve the Energy Efficiency of the Smart Home
Figure 5: Samsung Frame TV 2021 switches from Art Mode to Sleep Mode when no one has been detected for a user-specified time period.
switches the TV from Art Mode to Sleep Furthermore, falling prices for consumer combined with temperature and CO 2 sensors,
Mode when nobody has been nearby for electronics are increasing cost pressure on so the system is activated as needed — for
a user-specified time. This not only saves components. Hence, 3D time-of-flight (ToF) example, when someone is in the room,
energy but also extends display lifetime. and camera sensors are often too expensive when the CO 2 level is too high, or when the
to be implemented for presence detection. temperature exceeds the predefined limits.
RADAR SENSORS ARE THE Even powerful PIR solutions, which not only Whereas other sensing technologies often
MOST SUITABLE SENSING OPTION affect the design of the product housing provide only binary information such as pres-
FOR SMART-HOME DEVICES but also require an additional Fresnel ence or absence, a radar sensor can also check
Of all the available motion-detection solutions, lens, amplifier, controller, etc., increase the number of people in the room and adjust
radar sensors have the highest sensitivity even the bill-of-materials cost. Infineon’s the level accordingly at an early stage, or even
for the smallest movements, some of which are BGT60LTR11AIP radar sensor, by compari- check the people’s positions and distances to
even invisible to the human eye. PIR sensors son, requires only a minimum of supporting control the direction of the airflow.
cannot compete in terms of sensitivity. Also, components, especially in autonomous oper- There are many other possible use cases
radar does not rely on body heat as PIR sensors ation, and therefore has the smallest impact — for example, sound systems that track the
do, because it is an active sensing technology. on system costs. Because of their tiny size, position of the listener and continuously
This ensures that a person is detected even radar sensors can also be incorporated into optimize volume and sound parameters
when they are barely moving or not moving at small and thin electronic devices. accordingly; TVs with child care, which mea-
all. But arguably one of the biggest advantages In addition, radar sensors are robust in sure the viewer’s distance and give a warning
is detection through non-conductive materials. dusty, smoky, or humid environments where if the child’s eyes are too close to the screen;
While infrared, ultrasonic, camera, and other some laser-based ToF sensors or other or devices for the elderly or people in need
image-based sensors must not be covered or image-based sensors might be subject to of care, such as alarm systems that call for
require openings in the product housing, deteriorations in their detection performance. assistance in the event of a fall. Thus, with
a radar sensor can be completely hidden little effort, radar sensors can save energy and
inside a device. As a result, you do not have ADDITIONAL SMART FUNCTIONALITIES contribute not only to people’s comfort but
to make any compromises in the design of ENABLED BY RADAR SENSORS to their personal well-being and safety in a
the product and can avoid additional manu- Poor handling of devices also leads to smart environment. ■
facturing steps and costs for a housing with unnecessary power consumption. Users are
corresponding adaptations. not always aware of this, but they waste REFERENCES
Another possibility is camera-based motion energy unintentionally when they fail to 1 Martani, C., Lee, D., Robinson, P., Britter, R.,
detection — for example, for cameras, TVs, switch off their devices or adjust the settings and Ratti, C. (2012). “ENERNET: Studying the
laptops, and other devices that already have when they are going to be temporarily absent. dynamic relationship between building occu-
a suitable image sensor. Image systems have However, with the aid of radar sensors, this pancy and energy consumption.” Energy and
very high power consumption, though they can be regulated automatically so that users Buildings, 47, 584–591. bit.ly/3utyL73
may need good ambient light conditions, and don’t have to think about it but have the 2 Norford, L., Socolow, R., Hsieh, E., and Spadaro,
there is a need for image processing to detect assurance that they are not wasting energy. G. (1994). “Two-to-one discrepancy between
motion from a video, which further requires Besides being used as a presence or measured and predicted performance of a
a lot of energy. Lack of privacy is often also absence detector, radar sensors can add other ‘low-energy’ office building: Insights from a
cited as a concern, as camera-based systems functions to smart devices — for example, in reconciliation based on the DOE-2 model.”
invade private spaces, so users do not fully air-conditioning systems. In such applica- Energy and Buildings, 21(2), 121–131.
trust them. tions, radar sensors are most efficient when bit.ly/35FRQIB
www.eetimes.eu | MARCH 2022