Oct 01, 2008Until recently, tool-tracking systems, such as identifying tools with human-readable markings or bar codes, relied on the diligence of the worker, so they were prone to breakdowns. Radio frequency identification brings new efficiencies to tool-tracking systems. These systems are fully automated, so they eliminate human errors and free up workers to perform their primary job of putting things together without worrying about the tools needed to perform the job.
In general, all RFID tool-tracking systems need to be able to:
• Unambiguously identify a tool
• Locate a particular tool on demand
• Track the movement of a tool within a facility and at entry and exit points
• Associate all tools that are part of a set needed to execute a particular job
• Automatically transmit the movements of tools to a system of record
• Record that a tool has been issued to or is in the custody of a particular employee
RFID vendors take different approaches to fulfilling these requirements. The RFID Research Center at the University of Arkansas has had hands-on experience with all of the RFID tool-tracking systems we look at in this article, and has helped several companies investigate and deploy them—from large vehicle manufacturers to small repair facilities. We've found that there's no single "right" solution.
One company, for example, might need to deploy its system in a facility where there's a lot of interference from metal racks and storage bins, while another might want to integrate tool tracking as part of an asset-management system. Other variables include the precision with which the tools need to be located, the openness of the manufacturing space and the potential return on investment—whether you need to locate a $1,000 specialized drill bit or a $50 ladder.
It's important to note that RFID tool tracking is a developing application, and RFID vendors are adding new technologies to their systems to make them flexible. For instance, some manufacturers may need to track tools in large, open spaces as well as in small, confined areas. Many of the systems have been available for less than a year, and while some have been deployed, others are still in the pilot phase. Based on our experience, here's a guide to help you decide which technology will work best in your manufacturing environment.
Identifying and tracking tools with passive Gen 2 UHF tags is a good option for companies that have open manufacturing environments, especially work spaces that don't contain a lot of metal racks or storage bins. That's because UHF tags are susceptible to interference from metals and water. These systems are also good for companies that use disposable tools, such as drill bit kits and saw blades, because UHF tags are relatively cheap, making them more expendable. Since this is passive technology, the range is limited compared with active technologies. Tools can be accurately located anywhere from within 1 or 2 feet to several yards.
Two vendors working in this field are Mojix and RF Controls. Both use phased-array antennas to read tags. Depending on how these systems are implemented and tuned, they can give simple feedback—the tool is inside or outside the current read area—or more precise location information.
Battery-Assisted UHF System
For companies that want the benefits of UHF tags but need a longer read range, Intelleflex offers a battery-assisted UHF tool-tracking system. The tags include a small battery that gives a "boost" to the passive UHF signal, so they can be read from up to 100 feet in open space.
Wi-Fi Systems
If you have a Wi-Fi network in your manufacturing facility, you could save money by opting for a Wi-Fi tool-tracking system. It uses existing Wi-Fi access points to determine the location of tools, and requires minimal, if any, infrastructure to be installed. Wi-Fi systems actually work better in enclosed spaces, with lots of side rooms or hallways, because walls and barriers help to differentiate among various access points.
Typically, a Wi-Fi system does not provide a tool's precise location, but rather identifies a general area within several yards. For example, it may be able to determine the room a tool is in, but not necessarily the shelf or bin in that room where the tool is stored. These systems can be very useful for tracking tool carts, especially in enclosed storage areas or manufacturing facilities where it would be difficult or expensive to install a reader infrastructure. Wi-Fi systems are available from AeroScout and Ekahau.
IPICO offers a dual-frequency system that enables the tags to receive and transmit at different frequencies, reducing susceptibility to interference from environmental factors. The system operates very much like passive UHF systems, with similar locating abilities, and, like UHF, the tags are much cheaper than those used in active systems. So what's the difference between passive Gen 2 UHF systems and dual-frequency systems? Basically, it comes down to which communication protocol you prefer.
AeroScout, Indentec Solutions and WhereNet all have technology solutions that operate in multiple frequency ranges and can coexist to solve various tracking needs. They either have several different systems that work in parallel, or different systems in different areas that don't overlap. Take the example of tracking the tools on a tool cart. One solution could be used to track the cart around a factory, where it only needs to be tracked through chokepoints, such as dock doors into manufacturing areas. A complementary technology that provides more precise tracking could be used to identify and locate the individual tools on the cart.
Ultra-Wideband Systems
If you need to locate tagged tools precisely—to within a few feet—you should consider an ultra-wideband system from Multispectral Solutions, Time Domain or Ubisense. These systems use active technology, so they're less susceptible to interference from metal racks or dividers, and they're especially well suited to large, open areas—they can locate tools within a few hundred feet of linear detection range.
RuBee
Visible Assets is the only company using RuBee technology for tool- and asset-tracking applications. It operates in the low-frequency range, so there are few interference issues with metal, making it a good option in areas with metal storage racks or dividers. RuBee uses a unique, shapeable antenna design that's basically a long metal loop that can be fitted around door portals or floor spaces, so it's easy to configure in a variety of manufacturing environments. Also, the antenna material is cheap, making RuBee a low-cost technology. The system reads tags that move into or out of that portal loop, so it can tell you whether tools are in the room, although not their specific location.
• What kind of tool do I want to track—is it disposable, or do I need to track it for a long period of time?
• What does my manufacturing facility look like—is it open or enclosed, and does it have a lot of metal or other factors that would make it difficult to install a reader and antenna infrastructure?
• How precisely do I need to track my tools—to a single area, or to a specific shelf or drawer in a workbench?
• How important are these tools—do my manufacturing processes require a robust, expensive infrastructure, or will a cheaper, less accurate system satisfy my process requirements?
These four questions should help you narrow down the choices to find a system that's best suited for your needs.
Who's Who in RFID Tool-Tracking Systems
The RFID Research Center at the University of Arkansas has experience working with RFID tool-tracking systems from the following companies. The center does not directly compare equipment from different vendors or endorse any products.
• AeroScout
• Ekahau
• Identec Solutions
• Intelleflex
• IPICO
• Mojix
• Multispectral Solutions
• RF Controls
• SAVR
• Time Domain
• Ubisense
• Visible Assets
• WhereNet