Car-mounted sensors to monitor streetlights

MIT researchers have collaborated with infrastructure contracting company Forrevial in developing a monitoring system for streetlights that is inexpensive and highly automated. Their work aims to replace manual monitoring systems which see inspectors sent out, clipboard in hand, to examine the city’s streetlights one by one.

Ferrovial has contracts with several cities to manage their street-lighting systems, and was looking for more efficient ways of carrying out those tasks. MIT researchers including Sumeet Kumar and Sanjay Sarma came up with the idea to replace manual inspections with a set of cameras and sensors mounted on top of a vehicle, in much the same way that Google uses vehicle-mounted camera systems to generate its street views. Their study has been published in the journal IEEE Sensors.

The team proposed that portable equipment be mounted on the roofs of city-owned vehicles that would already be crisscrossing the city anyway, such as police cars, buses or garbage trucks. The vehicles would prowl the city’s streets at night, picking up the location of streetlights using digital cameras and sophisticated software to distinguish between streetlights and other sources of illumination, and even to estimate the height of each lamp. Other sensors measured the exact level of illumination, in order to determine if lights were failing, or if there were dark areas between lights indicating a possible lamp outage or a need for an additional light pole.

Tying this all together is a system for precisely determining the location of the vehicle as it moves along, thus creating an accurate map and database of positions. This system uses a combination of GPS data and other methods to improve accuracy, and could either record all the data for later downloading or send it in real time to a central facility. Such a detailed survey could provide a literal roadmap for potential upgrades of the lights.

Using efficient and long-lasting LED lights to replace older mercury vapour and other types of lighting could lead to significant savings on the costs of electricity and the maintenance needs for the lights. But without a monitoring system, noted Kumar, “we don’t have good ways of proving whether the upgrade was effective or not”. By comparing quantitative before-and-after data collected by the automated system, the improvements could be analysed with great accuracy.

While the research was specifically aimed at studying streetlights, Kumar said much of the basic work on the system — including the precision mapping system, algorithms for interpreting the information captured from the cameras and ways of capturing and storing data — could also be applied to tracking a variety of other aspects of urban infrastructure, including potholes and other issues in the streets themselves, the location and condition of signs and signals, and so on.

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