Barcelona has over 1500 km of sewage passageways traversing beneath the city and inspecting it can be a very daunting task. The tunnels in the system are very narrow and vary in size. They are also slippery, not well lit, and often contain pungent gases. FCC, a Madrid-based company, has pioneered a project that could address the challenges of sewage inspection.
The Aerial Robot for Sewer Inspection (ARSI) is a drone equipped with multiple sensors to help with assessing the water and air quality. It has a 3D camera for colour and depth which is used for calculating its position and speed. An onboard 2D laser is also used for detecting the walls and helping with calculating its flight path in real time. An infrared sensor is also installed for measuring the distance from the floor and assists with the flight altitude. At the heart of the drone is a small computer that can store and analyze all the data in real time. It has an autopilot used for directing the drone on its flight path by controlling the 4 rotors that power the drone.
The multitude of sensors are needed for the drone because drones normally rely on global positioning system (GPS) for determining its altitude and flight path but because of the subterranean nature of the environment, other sensors are employed to compensate for this shortcoming. This means that the drone has to calculate its position and speed all on its own based on the data that the sensors provide. Because the sewer system is pitch black, the ARSI needs to have its own lighting system. The small spaces that the drones travel through may cause turbulence from the rotor blades which makes flying difficult.
Despite the initial challenges, the advantages of using drone technology for sewer inspection are significant. The can cover more ground than a human team can, and it avoids putting human inspectors at risk from slips, falls, and postural issues. The drones are able to document far more information about the tunnels in a shorter amount of time and they can also be utilized as first responders to tunnel collapses in the sewage system to make a quick inspection of the site without putting any workers at risk.
Papa Sedó, the director of the Eurecat Robotics Unit which is co-developing the project, said: “This is the first time that the profitability of the use of drones in an activity such as the inspection of the sewage system has been analysed…the great flexibility and maneuvering capability of drones makes them ideal vehicles for subsoil inspection.”
The program is set to be fully implemented in Barcelona in 2018.
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