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Sensors to equip LED streetlights for smart lighting systems

Sensors to equip LED streetlights for smart lighting systems

Oct 17, 2016: It would be hard to imagine today’s world without artificial light – it allows us to continue our activities during the night, helps us feel safe and generally makes life easier. Public lighting lets us to move freely, to do what we want to, whenever we want to, independent of part of the day. Some studies suggest that public lighting lowers crime rates; other studies show that streetlights reduce the number of traffic accidents. The benefits of public lighting are obvious. However, there are also some disadvantages: high energy consumption and light pollution.
Streetlights consume high amount of electric energy. If the energy used for public lighting is not produced from renewable sources, it also increases carbon dioxide emissions, contributing to global warming. With increasing awareness about importance of saving energy and limiting carbon emissions, it is important to optimize the use of electricity in public lights. Recently, the advance in efficient LED lighting technology has somewhat minimized the energy consumption of streetlights. Still, every additional method of lowering the energy consumption saves money and protects our environment.
Light pollution, caused by excessive artificial light, disrupts ecosystems, causes increase in atmospheric pollution and can even have adverse health effects. Reducing light pollution in large urban areas, while preserving street lighting to increase public safety is an important challenge.
A way of solving this challenge is selectively turning on the streetlights when there is – pedestrian or vehicular – traffic present on the street. If the street is empty, there is no need for the streetlight to be turned on. The same method is already used to control the lighting in corridors in business buildings or hotels, and to control the lights in public toilets, but the existing motion sensors used in small confined areas are not suited for outdoor/street use, due to their short detection range, not reliable detection in all weather conditions and inability to precisely determine the location of each moving object.
Geolux has developed high quality radar sensors for outdoor smart lighting systems. The radar is attached on an existing street lamp pole and registers movement at distance up to 150 meters for pedestrians and up to 300m for car size vehicles. The radar sensors then wirelessly (using ZigBee communication) send the location of the detected object to nearby street lamps, so that the lamps closest to the object can be lit up. As detected person or car moves, the radar keeps following him and turning on lights around him. When the street is empty again, the lights gradually dim back to minimum intensity levels.
The recent project involved setting up smart lighting on a street that is 300 meters long. The street lamps are located at 30 meters from one another. To cover the whole street with radar coverage, two radars were placed on a central lamp pole; each radar observing a different direction.Instead of having the lights turn on in the evening, and keeping them fully bright until morning, the lamps were programmed to light up at default brightness of 10% when the street is empty. The two radars are monitoring movement on the street. When a pedestrian or a vehicle enters the street, one of the two radars in the street registers it and sends signal to the first lamp to increase brightness. As the object passes by the first lamp, the second one turns on, etc.

The speed of dimming the lights up, the duration of keeping the lights at full brightness as well as the speed of dimming the lights down can be programmed. This allows system integrators to fine tune these parameters in every setup.

Using Geolux radars to make streetlights smart results in energy consumption reduced up to 80%, prolonged lifetime of streetlights, reduced CO2 emissions and reduced light pollution. Geolux radars are destined to become indispensable building blocks for smart cities of tomorrow.

 Source: Geolux
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