Naval Surface Warfare Center Demos RFID Tool-Tracking Solution for Combat Ships

By Claire Swedberg

The system uses EPC Gen 2 UHF tags and readers to identify items loaded onboard, in cabinets stored within steel containers, enabling the U.S. Navy to reduce inventory-tracking time from 32 hours to two minutes.

The Panama City Division (PCD) of the Naval Surface Warfare Center (NSWC) has developed and demonstrated an RFID-based cargo-tracking solution that it says is poised to provide a 3,000 percent return on investment by eliminating the need to perform manual inventory checks. NSWC supplies research, development, test and evaluation services for surface-ship systems and subsystems. The solution was designed for a littoral combat ship (LCS), a small surface vessel intended for operations close to shore. By affixing passive ultrahigh-frequency (UHF) RFID tags to tools stored in metal cabinets within containers loaded onto such vessels, NSWC PCD was able to capture location data regarding those items in real time—even when a vessel was out to sea—using satellite-communications to transmit RFID data.

Smaller than the U.S. Navy's other frigates, littoral combat ships is serve a variety of functions, including moving cargo to and from port facilities. The two LCS vessels currently in use by the Navy are loaded with steel containers containing cabinets used to store a wide variety of tools, such as wrenches and ropes being moved between other vessels and the port. Without an RFID solution, the Navy—in order to ensure that all tools are accounted for—must assign its sailors to conduct manual inventory counts of all items within the containers, either on the vessel or at the port. This can take as much as 32 hours to complete every time it's done, says Ryan Mabry, the NSWC PCD computer engineer who developed the software for the RFID-based solution.

NSWC PCD's Ryan Mabry

It is not easy work, Mabry notes. Sailors often must stand in a tight enclosure (an 8-foot-by-20-foot container), manually checking items on paper. However, he reports, that time was reduced to approximately two minutes using radio frequency identification.

The solution, known as the Mission Package Automated Inventory Information Inventory System (MPAIIS), consists of EPC Gen 2 passive UHF RFID tags attached to items, as well as readers installed within containers, satellite-communications technology to transmit RFID read data to the back-end system—or a Wi-Fi connection, when a vessel is in the port—and custom-built software to manage read data and issue directives to the interrogators to capture RFID reads remotely.

NSWC PCD began looking into an RFID solution in 2008. Testing, research and development of the system extended to June 2011, when an onboard demonstration was conducted. The researchers are now awaiting funding so they can continue the development for additional containers.

The group conducted a series of tests at NSWC's laboratory facility located in Panama City, Fla., reading 50 different types of active, passive or semi-active tags placed in various areas of the cabinets, as well as moving reader antennas around a prototype container in order to achieve maximum coverage. Instead of creating a system that reads tags attached to tools passing through an RFID reader portal as they are loaded into containers, NSWC wanted readers and antennas to provide real-time information, on demand, by being built directly into the containers. The software was designed in-house to read the tags' ID numbers, link that data to specific inventory items and provide a full list of which items were in a specific cabinet within a particular container, as well as which were missing, whenever a vessel left the port destined for another vessel, returned with a different load or had its cargo swapped out.

Researchers found that the best combination of technology was the use of EPC Gen 2 passive UHF RFID tags attached to tools, with readers mounted inside the containers and antennas installed within the metal cabinets.

"We did lot of experimenting with tags," Mabry says. The researchers utilized a variety of tag makes and models, including those provided by Omni-ID and Confidex. According to Mabry, certain tags work well with metal, others on wood, with both materials present on some tools. The researchers also experimented with ways to ensure that tags are not knocked off while tools are in use. In some cases, the tags were located within a tool's interior.

Of the tags tested, Mabry says, "the highest success for this application came from the Omni-ID Max and Confidex tags in a generic tagging situation. The final choice of tagging for the future implementation has not been decided."

Four Alien Technology ALR 9900 fixed readers were installed inside each container, for a total of 16 antennas mounted within the metal cabinets. The readers can then interrogate each tag's unique ID number, and forward that data to the NSWC software onshore via a satellite connection.

When conducting an inventory count of items stored within a container, a user can open the software and begin a search based on a single item, all assets in a single container or all cargo within multiple containers aboard a particular vessel. The system issues instruction to the readers, and then displays a list of goods that should be loaded into the cabinets. Each item's ID is displayed in red if the RFID tag attached to it had not been read, green if its tag had been interrogated, or blue if an unexpected tool was found within that container. The user can select any item in the software and view a picture of it.

Staff members can then physically proceed to the container and either visually search for a missing item, or utilize a Motorola Solutions MC-9090 handheld reader to locate it, by selecting the specific product on the software loaded onto the handheld device, and then operating the reader as a Geiger counter until that item is located.

"We looked at third-party commercial software, but each time we wanted a change, we would have to go back to the contractor," Mabry says, "so we developed our own software in-house." The software consists of two modules: an inventory application and a management application. The management app allows the setup of readers, and links tag IDs with tool descriptors and photographs, while the inventory app determines whether or not items have been found, based on the RFID read data.

Mabry estimates that the Navy could save up to $14.5 million in inventory labor costs for 500 containers. After 10 years, he says, that would culminate in a 3,000 percent return on its investment.

The solution provides 96 percent inventory accuracy in less than two minutes, Mabry reports, and a 100 percent rate when repeated. The workload to perform inventory counts is thus reduced by 99 percent. What's more, he notes, the software could enable automated replenishment.

The MPAIIS system was demonstrated onboard the LCS Sea Fighter in Panama City, using one prototype container with four readers and sixteen antennas built into cabinets within that container. The solution exceeded its performance goals, Mabry says. Patents are currently pending.

The next step, according to Mabry, will be to test the solution at the Navy's Mission Package Support Facility, and to integrate the software with other Navy automatic-identification technology (AIT) programs.