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Six Sigma and the Single Tag

How do you achieve flawless read performance from your RFID system? By making sure it interrogates only one tag at a time.
By Pat King
The Answer

The first practical action is to understand how to read one tag reliably. What are the limits—in terms of speed, distance, attenuation, orientation, interference, and so on—of your ability to read a single tag?

Once you have answered that question, you have the raw material for a successful implementation of a Six Sigma RFID system and can look forward to automation with assurance and confidence of high reliability.

"Hold on," you say. "Not so fast. That sounds too naive and simple."

I assure you, the solution really is just that simple. Once you know how to read a single tag, you can then step back a take a look at the bigger picture. This is usually referred to as a site survey and business-case analysis. The problem is, until you understand how an appropriate individual tag and reader perform in this environment, you should not do any kind of site survey and business-case analysis. As you approach the site survey, ask yourself this: What opportunity do I have for singulation? If you find, by some good fortune, that the entire application lends itself to singulation, then you already have the formula for Six Sigma RFID reliability.

Most of you will have more complicated requirements, but maybe you don't. Try to force singulation into your requirements, even as a new or reengineered process. If you can, then you have a solution for Six Sigma RFID and will be the envy of your industry.

For those who need to read further, let me provide a few examples of how this practice can be applied to current manufacturing and supply chain processes. Let's assume you have an over-the-belt application and need to read a large variety of designs of RFID labels on boxes, and that the belt runs at 600 feet per minute. I am sure you are laughing at me right now, and that your current answer is to add more and more readers in all sorts of bombastic orientations to compensate for the infinite number of orientations you imagine likely. Most likely, you are adding triggers and sensors and gauges. Rube Goldberg would be proud of you.

Yes, you will eventually catch the mouse, but if you have ignored singulation, I cannot warrant that you will ever have reliability, much less Six Sigma reliability

At this point, I want to show why RFID is better than bar coding, as I am afraid I may have turned you off by now. If you apply the same singulation principal to bar codes, you will still have the same problem—that the laser must find the bar code, and the bar code optics are limiting. The performance level of modern cameras is unbelievably high, but even if you move to a camera, you will still have endless problems, including maintenance of the optics.

If you are still unconvinced that singulation-base RFID deployment will yield Six Sigma results, here are three case studies:


Sanjay Chawla 2006-01-30 01:36:23 PM
Six Sigma and the Single Tag If reading RFID tags one at a time becomes a requirement for reliability, then barcode is a better solution. It is much cheaper and you can see what your are reading. The case studies, presented in the article, supporting RFID will not be enough to overcome the cost factor.
Damon McDaniel 2006-10-24 12:58:29 PM
Singulation Mr. King, Your performance issues and therefore basis for your article is that RFID reads are NOT reliable (enough) and the only way to get there is to read all cases/items separately. Let me ask a question of you. Might you be referring to Gen 1 tags (class 1 & class 0)? And, at what frequency(ies)? I'm not a RF engineer, so because of that I HAVE to do a ton of reading & researching to keep abreast of the technology. From what I read - most of the relaiability issues have either been solved by Gen 2 developments or were truly site environment circumstances that may have called for a particular solution/frequency and because individuals were rushing to do RFID - were applying the wrong solution attempting to get the reads they were looking for. Apologies if that was confusing - but for example - look at the developments of near-field UHF vs. far. Here - the liquids pose no problem whatsoever and even metals can actually be used to ENHANCE the read ability. I don't think it matters much if you have 1,000 reads per second ability or 400. From a practical perspective - no one has proposed having a scanner sit on top of a truck bay and scan the entire truck contents for item-level tags. You probably would have reliability issues. You'd definitely also have data overload. Anyway - when a forktruck removes a pallet from a truck - usually what is desired is the pallet scan to confirm the ASN & determine it's routing - 100% reliable (if I assume proper function as you did). If the pallet requires "breakdown", then a further scan will usually capture the read on a moving conveyor to obtain the case read (also now 100% reliable in most properly constructed zones). True Six Sigma reliability will only happen when the tags & the rest of the supporting infrastructure are 100% reliable. The readers are almost there today (with proper construct). Think also of the developing RuBee & other technologies and how they will continue to improve performance issues. I felt like you were insuating that bar codes are "Six Sigma" reliable and the scanning process ususally is. But, for item level tracking - how many times have you purchased something like kids' flavored drinks - assorted flavors, yet the scanning clerk says "How many did you get?" - scans 1 and multiplies or repeats that over by your Qty? Item-level Six Sigma just disappeared. So, yes - RFID can & should be more reliable than bar codes and avail much to organizations as they discover creative ways to take advantage of the data as it becomes available. Warm Regards, Damon McDaniel

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