As sensor, RFID, and GPS-based location systems become increasingly interoperable, manufacturers are better able to monitor the location and condition of incoming and outgoing shipments within the context of the total supply chain. These "sense and respond" networks can help improve the security, quality, and integrity of products moving through the supply chain, including perishable foods, temperature-sensitive high-tech equipment, hazardous materials, and equipment prone to humidity-induced erosion (Figure 1).
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An Evolutionary Process
In the past, sense and respond networks were used primarily by the military and generally referred to RFID and other networks that identified the location and inventory levels of supplies. These networks enabled the armed forces to replenish critical supplies by placing immediate orders via the network, linking factory to foxhole. When homeland security concerns intensified following 9/11, industry accelerated the development of active RFID and sensor technologies to detect and alert personnel of security breaches of cargo containers, which are used to transport 90% of world trade.
 Figure 1. Sense and respond networks automatically track containers via a Web-based information service |
With security as the catalyst, many sensor technologies have been integrated with automatic identification and data collection (AIDC) platforms to evaluate and respond to all manner of environmental changes affecting the container and its contents, providing visibility from the source manufacturer to distribution centers and the final destination. Nanotechnology also is helping to create minute sensors that can gauge changes in levels of vapor or gas fumes, which provide a more granular means for detection and response.
Today, sense and respond networks consist of all types of automated wireless technologies working independently or together to identify, locate, and detect the security or condition of objects as they move through the supply chain. These networks then transmit their data to a centralized information system.
RFID-Based Networks
Modeled after the Defense Department's In-Transit Visibility (ITV) network (the world's largest active RFID-based tracking system), commercial RFID-based networks contain layers of AIDC technologies, especially sensor technologies. The centerpiece of these networks remains the active RFID device, a battery-powered RFID tag or seal that can communicate with fixed or handheld readers over ranges up to 300 ft., an ideal distance for extended supply chains.
Because of the global nature of supply chains, it's critical for the AIDC technologies to be based on international standards accepted throughout the world. The sense and respond supply chain networks gaining the most momentum use active RFID operating at 433.92 MHz and based on ISO 18000-7 standards, which has proven to perform best in metal-rich environments, such as around containers and seaports. The radio waves transmitting data at this frequency can bend around metal, unlike RFID signals using other frequencies, where metal can interfere with the transmission.
Another advantage of active RFID tags is their ability to store and transmit large amounts of data—up to 128 KB, which can encompass not only the entire manifest of a container but also its routing schedule and sensor data, essential in a sense and respond network.
Security Applications
The latest generation of active RFID tags can include sensors that detect container-door intrusions and measure light, temperature, humidity, and shock. In this application, the sensors are embedded in the tag, which is U-shaped and clamps onto the left-side door of an ISO-compliant cargo container (Figure 2). The sensors reside in the tag's compartment inside the container door and can detect environmental changes therein. The compartment also contains the tag's internal power supply and the electronics for memory and programmable read-write instructions. Sensor buses can be incorporated in the tag to handle additional sensors that detect anything from pressure and motion to radiation and hazardous chemicals.
 Figure 2. Sensors embedded in a tag clamped onto the door of an ISO-compliant cargo container |
For security purposes, a spring-loaded lever on the tag is cocked when the right-side door is closed, and it is triggered whenever there is an unauthorized opening of the door. A low-profile plate that encases the tag's RF antenna resides on the outside of the container door. This enables the tag to communicate programmed information as it passes fixed readers or handheld computers. The tags can come with audio alarms that signal potential security breaches.
Fixed readers typically are placed at the key hand-off checkpoints throughout the supply chain, which can number up to 20 or more in a typical journey of a cargo container. For example, many of the consumer goods available in the U.S. are made in China, so readers would be placed at the source manufacturing point, consolidation and deconsolidation points, rail heads and truck transportation transfer points, port gates, staging areas, loading and unloading docks, and distribution centers.
Nested Visibility
In addition to sensor data, active tags can also store data describing the contents of containers and shipments, whether derived from bar codes or passive RFID tags. This provides nested visibility—the capability to scan bar codes or passive RFID labels on boxes and cartons and upload the data to the active RFID tag or software platform—and allows shippers to track containers and goods at the same time.
MEATCO, a supplier of additives for meat and fish products, recently implemented this type of network to track the status of chilled and frozen beef in containers moving from Namibia (southern Africa) to the United Kingdom. In a partnership project, the U.S. Trade and Development Agency, World Customs Organization, SIMTAG (50% funded by the European Union), Savi, and others designed an open network platform to incorporate software applications linked with a variety of AIDC devices, including bar codes, sensors, passive and active RFID, and satellite tracking systems. The beef was monitored from loading facilities in Namibia to unloading facilities in the United Kingdom.
In another example, Mitsui & Co. (USA), a trading and logistics service, worked with Savi Technology to provide a sense and respond network for goods shipped by an international manufacturer of children's products from a factory in Guangdong, China, to the Port of Long Beach and nearby distribution facilities in southern California. Cartons and cases were source-tagged at the factory with EPC-compliant passive RFID labels and packed into containers equipped with active RFID tags. The nested visibility enabled the customer to automatically build a container manifest and then automatically track the container and its contents throughout its journey via a Web-based information service called SaviTrak.
Such a real-time network enables dynamic management by everyone involved because automated event-and exception-alerts allow trading partners—from the manufacturing facility to the end user—to adjust their plans when unforeseen events happen, as opposed to after the fact, when it's too late. This is especially true for temperature-sensitive goods, such as perishable foods, pharmaceuticals, and hazardous materials, where immediate response is necessary to ensure safe passage throughout the supply chain.
Mobility and Agility
RFID–based sense and respond networks are increasingly mobile and agile. Portable deployment kits the size of suitcases, weighing about 55 lb., can be used in remote locations and contain everything from site managers and dual-frequency RFID readers for passive and active tags to label printers, laptop computers, asset management software, and Iridium modems, with GPS to provide satellite links to the appropriate network server. In this way, tracking, sensing, and responding to shipments in transit can occur where there is no fixed-reader infrastructure.
A number of recent studies have shown that such networks are increasingly critical not just for those involved in transportation but also for the other players in the supply chain, including manufacturers. An A.T. Kearney report, "Synchronous and Secure Supply Chains: Application of RFID for Global Container Shipments," found that such networks enable shippers to comply more cost-effectively with RFID mandates from major retailers while gaining significant ROI for themselves, in terms of greater security, reduced inventory, lower transportation and labor costs, and fewer stockouts (Figure 3).
 Figure 3. Inventory management and optimization enabled by sense and respond networks |
A recent ARC Advisory Group report, "Supply Chain Management Worldwide Outlook: Market Analysis and Forecast through 2010," encouraged manufacturers to implement execution software more frequently to better synchronize manufacturing and logistics for improved returns. Good execution software helps manufacturers schedule raw material deliveries to their facilities and enhances control of supply levels and distribution activities.
"As global competition increases, existing manufacturing facilities are under incredible pressure to improve their return on assets," Tom Fiske, a senior analyst at ARC, recently stated. "To achieve higher levels of performance, these plants are adopting more solutions that better link manufacturing operations with business objectives. That increases their flexibility and agility, and that synchronizes their supply chain operations."
Linking execution software and other applications with automated sense and respond networks helps the entire supply chain community to ensure that the trillions of consumer products we use arrive safely, securely, and when we need them.
Chris Stephenson can be reached at Savi Technology, Sunnyvale, CA; 408-743-8000, [email protected], www.savi.com.