Recommendations for automatic identification technology in the Air Force supply chain

Air Force Journal of Logistics, Fall, 2006 by Thomas G. Yeung, Scott J. Mason, Justin R. Chimka, Michael A. Greiner

Introduction

In a white paper published by the Auto-ID Center at the Massachusetts Institute of Technology (MIT), Vivek Agarwal said that, in order to achieve real-time visibility of information, the following are needed: (1)

* Real-time data acquisition methods

* Conversion of acquired data into relevant information using standardized, secure representation

* Instantaneous access to this information

These points could not apply more to the United States Air Force.

All code-reading systems for automatic identification share the following generalized description. There is an item needing to be tracked and its accurate identification throughout the supply chain will be beneficial to the organization. Some form of coding device, such as a label or tag, is affixed to the item so that a wide range of information can be automatically read from the device. The code will be read from the device by any of a number of technologies including an automatic or hand-held bar code reader, optical character reader, magnetic stripe reader, vision system, or radio frequency interrogator. Once the code is read, it will be validated and converted into system-meaningful control and information output. The code reader transmits the output to other technologies (computers and so forth) for data manipulation or communication. (2)

Tags and Readers--Radio Frequency Identification

RFID Defined

Radio frequency identification (RFID) uses a radio frequency transmission to identify a person or object. A RFID transponder or tag responds to a radio signal sent by a reader. Tags store information such as a serial number, model number, color, or any other characteristics that may be of benefit. Tags are read by a compatible reader when they pass through its radio frequency field.

RFID is not a recent discovery. It was first implemented in World War II as a means of identifying friendly aircraft. However, only recently has RFID gained attention as a valuable method of identifying objects on a large scale.

Active Versus Passive RFID

Active RFID and passive RFID technologies are often combined as a whole when referring to RFID; however, they are fundamentally distinct technologies with substantially different capabilities. Effective supply chains do not rely solely on one particular technology, but use both active and passive technologies in complementary ways for complete visibility. (3)

Both active and passive technologies utilize radio frequency energy to communicate between a tag and a reader; however, the technologies differ by the means in which they are powered. Active RFID utilizes an internal power source (battery) for a continuous source of power. Passive RFID utilizes radio frequency energy from the reader to obtain its power. Because passive RFID relies on a reader, a passive tag is only on when it is communicating with a reader.

Applications of Active and Passive RFID to Supply Chain Visibility

Passive RND is best suited for applications where the movement of materiel is conducted in a highly consistent and controlled environment, and where there is not a need for security or sophisticated data storage or manipulation. Active RFID is more appropriate where materiel flow is dynamic and unconstrained, and where there is a need for enhanced security and data capabilities. Savi Technology outlines some of the main tasks of supply chain visibilities and recommends which RFID technology is best for each. (4) These tasks are outlined in the discussion that follows

Area Monitoring

Active RFID is the only practical technology for area monitoring. Because of the continuous nature of monitoring, only active RFID has the power supply for such applications. Savi Technology suggests active RND for the following types of area monitoring: (5)

* Collecting real-time inventory information within a warehouse

* Monitoring the location of empty and loaded air cargo containers across an air terminal or tarmac

* Monitoring the security of ocean containers or trailers stored in a yard or terminal

Spot-Level Locating

One means by which RFID enables visibility is by automatically collecting data on materiel as it flows through the processes. In order to accomplish this, readers must be precisely located at specific points within a process. Savi Technology provides the following examples of spot level location: (6)

* Identifying the exact parking slot of vehicles in a truck yard

* Identifying the specific storage rack of a pallet within a distribution center

* Identifying the specific loading bay in current use by an air cargo unit load device

High-Speed, Multi-Tag Portal Capability

A variety of portals can exist in a supply chain. By definition, a portal is any type of doorway, gate, or opening through which materiel flows. Examples may include dock doors at a distribution center, entry or exit gates at an intermodal terminal, and conveyor checkpoints in a parcel sorting operation.

In order for a reader to identify multiple tags flowing through a portal, it must be able to collect information from multiple tags at high speed, while at the same time differentiating between the tags within the specified portal area and those in surrounding areas. Large-scale application, such as roadside monitoring, is available only with active RFID because it has the necessary range. Passive RFID can handle small to medium size portals such as doorways and conveyor checkpoints, but lacks range and can only read tags moving relatively slowly (5 to 10 mph or less). Dual-range active RFID offers the most versatile means of identifying multiple tags through a portal. It is capable of reading tags at a very high speed (greater than 60 mph) and can handle small, medium, and large scale applications.