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Cell towers are often taken offline when a natural disaster strikes, and the result is a lack of communication, making it harder for people to call for help and be located. A team of researchers has repurposed a drone to create an aerial cell tower to ping phones in the area and find the missing person. 

The new search and rescue drone was designed to provide first responders with an all-in-one victims localization system capable of working in the aftermath of a disaster without existing network infrastructure support.

As the system uses a drone, it is fully battery powered and could even open up the possibility of creating a makeshift cellular network, allowing emergency services to locate people and people to call their loved ones.

The team built the product using off-the-shelf hardware and called it the search and rescue drone-based solution (SARDO). 

How does it work? To detect and map out the locations of victims, SARDO performs time-of-flight measurements (using the timing of signals emitted by the users’ phones to estimate distance). 

A machine learning algorithm is then applied to the time-of-flight measurements to calculate the positions of victims. The algorithm compensates for when signals are blocked by rubble.

If a victim is on the move in the wake of a disaster, a second machine learning algorithm, tasked with estimating the person’s trajectory based on their current movement, kicks in—potentially helping first responders locate the person sooner.   

After sweeping an area, the drone is programmed to automatically maneuver closer to the position of a suspected victim to retrieve more accurate distance measurements. If too many errors are interfering with the drone’s ability to locate victims, it’s programmed to enlarge the scanning area, as explained by spectrum.iee.org.

The team plans to extend SARDO to emergency indoor localization and assist in any emergency scenario where buildings might not be accessible to human rescuers.