Drones relay RFID signals for inventory control

System could save retailers billions lost through faulty inventory records.

Radio frequency ID tags were supposed to revolutionize supply chain management. The dirt-cheap, battery-free tags, which receive power wirelessly from scanners and then broadcast identifying numbers, enable warehouse managers to log inventory much more efficiently than they could by reading box numbers and recording them manually.

But the scale of modern retail operations makes even radio frequency ID (RFID) scanning inefficient. Walmart, for instance, reported that in 2013 it lost $3 billion in revenue because of mismatches between its inventory records and its stock. Even with RFID technology, it can take a single large retail store three months to perform a complete inventory review, which means that mismatches often go undiscovered until exposed by a customer request.

MIT researchers have now developed a system that enables small, safe, aerial drones to read RFID tags from tens of meters away while identifying the tags’ locations with an average error of about 19 centimeters. The researchers envision that the system could be used in large warehouses for both continuous monitoring, to prevent inventory mismatches, and location of individual items, so that employees can rapidly and reliably meet customer requests.

The central challenge in designing the system was that, with the current state of autonomous navigation, the only drones safe enough to fly within close range of humans are small, lightweight drones with plastic rotors, which wouldn’t cause injuries in the event of a collision. But those drones are too small to carry RFID readers with a range of more than a few centimeters.

The researchers met this challenge by using the drones to relay signals emitted by a standard RFID reader. This not only solves the safety problem but also means that drones could be deployed in conjunction with existing RFID inventory systems, without the need for new tags, readers, or reader software.

“Between 2003 and 2011, the U.S. Army lost track of $5.8 billion of supplies among its warehouses,” says Fadel Adib, the Sony Corporation Career Development Assistant Professor of Media Arts and Sciences, whose group at the MIT Media Lab developed the new system. “In 2016, the U.S. National Retail Federation reported that shrinkage — loss of items in retail stores — averaged around $45.2 billion annually. By enabling drones to find and localize items and equipment, this research will provide a fundamental technological advancement for solving these problems.”