RFID Directionality (i.e. the direction a tag is traveling past the RFID read) has been a sought after capability since RFID was introduced to the commercial market in the 1970’s. While the evolution of RFID technology has made great strides over the years, these technological advancements have for the most part been limited to the packaging, operating environment, standards adoption, and cost elements. The basic function of using RFID technology to identify the existence of an item(s) at a particular location, at a particular point in time has not changed much.
Because of the universal need for passive RFID tag directionality, coupled with the lack of inherent technical capability within the RFID ecosystem, the industry has tried a few “workarounds” to provide this capability. These “workarounds” have included the setup of multiple antennas (essentially along the tag path) and determining which antenna was the first to read the tag which helped determine direction. This “workaround” is expensive and also requires the physical space necessary to set up multiple antennas that will not contain field overlap. Another tactic that some vendors have pursued is to measure the phase of the RFID tag signal which can be returned if a vendor’s reader provides Low Level Reader Protocol (LLRP) data. This method involves measuring the signal phase of a tag at several points in time as it moves through the antenna’s field of view. This “workaround” also has its pitfalls since there are so many variables that are difficult to control in the real world in order to get an accurate determination of direction. (i.e. – the tag direction calculation is based upon a formula that assumes the tag is moving through the antenna’s field of view at a constant velocity, and at a constant height relative to the antenna location, etc.) It’s safe to say that while some of these techniques may be of some use within certain environments, they are certainly not the answer for everyone; especially anyone who requires 99%+ accuracy with their inventory and/or assets.
Within the last year or so, a company called Impinj, has introduced the technology that will finally make this a reality. They call it their xArray Gateway.
This gateway is a ceiling mounted robust RFID reader, is “Always-on” and uses a combination of proprietary antennas within the gateway to track multiple tags in 2 dimensions in pseudo real-time. It can track the identity and location of an item reading up to 1000 tags per second in a 1500 sq. ft. area. It is getting good reviews within the retail industry.
Versona Systems believes that this technology will someday evolve into a production-solid product offering for the manufacturing and distribution industries. However, at this point we would consider this technology (version 1.0) to be a bit immature to be realistically considered for most manufacturing and distribution companies. We think the first adopters of this technology will be retail and healthcare. Impinj believes their “Always-on” gateway is well suited for manufacturing. But we are not aware of any wide-spread use in that environment to date.
Here are a few of its current shortcomings (as we see them):
1. The ideal ceiling height for this product (according to Impinj’s specifications) is between 10-15 feet. Most of the ceiling heights where we work are anywhere from 25-40 feet up. We are not sure what effect that would have on the reader’s ability to track items beneath it.
2. We have not been able to do any testing with this new reader/gateway. This gateway may not detect a tag on a pallet that is buried beneath 30-40 other tags (especially from 40 feet up) much more testing is needed.
3. Again, because of the lack of testing with this new technology, we don’t know if this reader/gateway could read all tags on a pallet 100% of the time. (i.e. – if the forklift is putting a pallet of plastic containers on the trailer and that pallet contains 48 parts, we would want to be absolutely sure that the tracking system has accounted for all 48 parts)
In today’s fast paced market, many businesses are unable to make sound decisions based on inventory data because the updates are not frequent enough for split second decisions with the demand of internet transactions. Understanding RFID tag directionality is important to making decisions on inventory flow and location for an item in real time. As the demand for inventory visibility grows with the internet, the new era of RFID of “Always-on” item intelligence is a must. Versona experts believe this will be a game changer in the RFID space and our team is watching this closely.