Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2000-12-12
2003-07-29
Mullen, Thomas (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S005920, C340S010100, C340S505000, C700S215000, C700S226000, C700S229000, C705S028000
Reexamination Certificate
active
06600418
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to object tracking and management systems and methods, and more specifically to such systems and methods that use a combination of mobile and/or stationary radio-frequency identification tags to identify, monitor the locations of, and direct movements of objects.
BACKGROUND OF THE INVENTION
To achieve highly efficient warehouse operations, it is desirable to accurately track the movements of pallet loads and other objects to be located and/or transferred within the warehouse as they are transported to and from various locations, such as storage locations, stocking locations, staging areas and loading docks. In typical conventional warehouse management operations, the operator of a transport vehicle, such as a fork truck, reach truck, lift truck or pallet truck, receives a set of printed stocking or picking orders, typically generated by a computer, and executes the orders by visually identifying the loads and locations and transporting the loads to and from the locations specified on the orders. In such a system, especially in large-scale warehouses with a large number of locations and loads to handle, there are numerous opportunities for errors.
Some warehouse management operations use bar codes which are affixed to the loads or which mark specific locations. In a typical example of such a system, the operator uses a hand-held bar code scanner to read the bar code on the loads and, in some cases, on the stock locations. Although such a system is an improvement over purely visual processes, it can be difficult to completely implement, due partly to the need for direct line of sight, close proximity, and proper alignment between the scanner and barcodes. It also requires the operator to participate in the load-identification process. In some case, the operator may need to exit the transport vehicle to scan the barcodes manually, slowing down warehouse operations. Certain locations, for example high storage shelves and loading docks, often are particularly difficult places for using bar codes because of the need for close proximity between the codes and the reader. As a result, loads in those areas are often visually identified instead.
Radio-frequency identification (“RFID”) tag systems have been proposed for use in inventory tracking. In such a system, an RFID tag is attached to an object or location, and contains a non-volatile memory for storing information identifying the object or location and electronic circuitry for interacting with an interrogator. RFID tags may be passive or active. In the case of a passive RFID tag, the tag includes circuitry for converting at least a portion of the received RF signals into electrical power needed by the tag for signal processing and transmission. In a typical conventional system, RFID tags containing information associated with the identities of inventory items to be tracked are attached to the inventory items. An RFID interrogator is used to detect the presence of an RFID tag and read the identification information from the tag. A typical RFID interrogator includes an RF transceiver for transmitting interrogation signals to and receiving response signals from RFID tags, one or more antennae connected to the transceiver, and associated decoders and encoders for reading and writing the encoded information in the received and transmitted RF signals, respectively. The interrogator may be a portable device, which can be brought near the tags to be read, or it may be a stationary device, which reads the tags as they are brought to the interrogator, as in the case of tagged library books being returned to a return station that is fitted with an interrogator. RFID tags may also be affixed near a location as a location marker. After detecting both a tag attached to an inventory item and a location marking tag, a processing unit associated with the interrogator may determine that the inventory item is positioned near the tagged location. While these conventional object tracking systems are capable of keeping a record of the inventory items and sometimes their locations, they are not effective for tracking and/or managing the movement of the inventory items.
There also exist warehouse inventory tracking systems that include fixed RFID interrogators at various locations to detect RFID-tagged items when they are positioned near the interrogator-equipped locations. For example, there are warehouses with RFID interrogators positioned at or near the loading dock gates. Such systems are capable of tracking the arrival of tagged items at the various locations, but are not capable of detecting errors remote to these locations. For example, if a fork truck picked up a wrong load because the truck was driven to a wrong pick-up location, the error would not be detected until the load had reached the gate. This delayed error detection negatively impacts the overall efficiency of warehouse operations. Additionally, outfitting each of the numerous loading dock gates with an interrogator is not cost effective.
It is desirable to provide a system that provides full automation to the process of object identification, movement and tracking throughout a warehouse or other similar environment. There is a need for such a system that is adaptable for use with all of the wide variety of locations that are involved in warehouse operations, such as stocking locations, storage racks, floor lanes, and shipping docks. There is a need for such a system that operates in conjunction with a central data repository to direct and track all object movement throughout the entire warehouse.
The present invention is directed to alleviating one or more of the aforementioned problems, and meeting one or more of the above-identified needs.
SUMMARY OF THE INVENTION
The invention provides for an automated object and location identification system, preferably for use in warehouse management operations, without the need to outfit numerous locations with fixed RFID interrogators. In one embodiment of the invention, a transport vehicle, such as a fork truck or reach truck, has mounted thereon an RFID interrogator. RFID tags are attached to objects (such as pallets and loads) and to locations (such as a storage location, pass-through location, or loading dock). In the case of a pallet, the information transmitted from the tag may include the identity of the pallet, the weight of the pallet, and an identification of the items on the pallet. In the case of a location, the information is indicative of the location, such as a location code or coordinates. The RFID interrogator transmits interrogation signals to the RFID tags. Each of the RFID tags transmits a signal encoded with the information particular to the tag in response to the interrogation signals when the vehicle is sufficiently close to the tag, though not necessarily within a direct line of sight.
A processor is operatively linked to the RFID interrogator for processing the signal received from the tags by the interrogator and determining the identity of the load and position of the detected location RFID tag. The processor may be located on board the vehicle, at a remote site, or at a combination of both.
RFID tags are preferably used on both the objects and the locations. Alternatively, an identification marker such as a barcode tag may be attached to the objects, while RFID tags are used at one or more locations. In this case, the interrogator on the transport vehicle also includes a barcode scanner for reading information stored in the barcode tags. Similarly, RFID tags may be used on the objects, while barcode tags are used at locations, such as alongside a loading dock door.
Preferably, the processor provides the operator with feedback information through a user interface on the identity of the object, the location where the object is positioned and the location to which the object is to be moved. For example, the processor may transmit an audible signal (such as a beep) or a visual signal (such as red or green lights or graphical display on a monitor) to the operator to
Francis Robert C.
McGee James P.
Sainati Robert A.
Sheehan, Jr. Richard L.
Tong Sai-Kit K.
3M Innovative Properties Company
Buss Melissa E.
Mullen Thomas
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