There are several challenges that I have consistently heard about from end users. One involves reading only the tags you want to read while driving a forklift truck around a warehouse. At one time, companies had trouble reading all tags on a particular pallet being carried. Now, passive ultrahigh-frequency (UHF) tags and readers have improved such that the problem is no longer reading tags on a pallet, but rather picking up tags on pallets, cases or items on shelves as a driver rides around.
This problem can usually be resolved by using software to filter out reads. The software must be intelligent enough to distinguish between a tag read as a forklift truck drives by (the tag will be read only a few times) and a tag on a pallet being carried by the forklift. Tags on a pallet being carried by a forklift will be read hundreds of times—maybe even thousands of times—as the vehicle moves around a facility.
Another issue involves associating a tagged pallet or container with an exact rack location. The ideal situation would be to place a tag on a specific rack and then read that tag as the forklift puts away the pallet or container. Software could then associate the tag on the pallet with the one on the rack. However, most companies have found that there are too many stray tags within the read field to accurately and consistently identify each rack tag.
Some firms have embedded transponders in their warehouse floor at each rack location, and have placed a reader antenna under the forklift. When a truck stops at a particular location, the tag in the floor is interrogated and associated with the tag on the pallet being put away. One problem with this system, however, is that it doesn’t tell you whether the tagged object was put on the lowest, middle or highest rack.
A company known as TotalTrax (formerly Rush Tracking Systems) developed a solution that utilizes bar codes on ceilings and a camera to precisely identify a truck’s location, so that a tagged item can be associated with a specific rack location. But like the tag in the floor, the system cannot tell you on which specific rack the tag was placed.
I have heard some companies talk about putting height sensors on a forklift to determine rack location, but I think this will be addressed via vision technology. Video analytics has improved to the point at which a system could be set up so that when a forklift truck puts a pallet away and starts to back up, a camera can capture video of that location and analyze an alphanumeric location plate. This is then associated with the pallet tag, providing an exact location. If that item is moved, the system will update automatically.
There is a great deal of end-user interest in such a solution, so I am surprised that no company has yet put together a complete package of technologies to solve these problems.
—Mark Roberti, Founder and Editor, RFID Journal