A new inventory management system developed and patented by a Missouri S&T computer engineer virtually eliminates frequency interference issues at facilities that use RFID (radio frequency identification) readers to manage inventories and track products.

“Our system reads and manages inventory in real time with a nearly 99 percent read rate,” says Jagannathan Sarangapani, the William A. Rutledge-Emerson Electric Distinguished Professor in Electrical Engineering. “Previous systems had only a 60 to 70 percent read rate.”

Sarangapani says RFID systems allow goods to be tracked from “cradle to grave,” recording the chain of custody from the point of manufacture of all the product’s components, to the point the consumer receives it.
Facilities that use RFID systems have a network of distributed scanners that read radio frequency chips or tags that are incorporated into or attached to products or materials within them.

A number of factors can affect the ability of RFID readers to successfully read product tags. “Tag interference” occurs when multiple readers attempt to read a tag at the same time. “Reader collision” occurs when multiple readers are used and a carrier signal from one reader interferes with another. Reader collision makes the tags unreadable and lowers overall read rates.

Sarangapani and his associates overcame these challenges by developing software that activates and deactivates adjacent RFID readers within the facility based on the tagged product’s location. The software also queries an inventory database based on information collected from the item’s tag.

“If shelves are empty of a product, or if a product is about to expire, it will alert the system,” Sarangapani says. “Employees can also track when the next shipment is coming.”

An additional benefit of the new system is its ability to read tags on frozen goods. “Many chemicals and medicines must be kept refrigerated or frozen,” Sarangapani says. “Other systems cannot read tags on frozen items, so they have to be thawed first to be inventoried. Thawing sometimes makes the product unusable and it must be destroyed.”

Also named on the patent are Anil Ramachandran, MS ECE’07, Kainan Cha, ECE’04, MS ECE’06, and Can Saygin, a former S&T professor who is now with the University of Texas at San Antonio.