Abstract:
A device, which may be mobile, comprises a data reader, scale, alarm indicator, and processor. The reader is capable of reading data encoded on an item within a reading zone, thereby generating read data. The item may be a pallet loaded with bulk articles. The device, if mobile, is positionable such that the item is within the reading zone and on the scale. The scale generates measured weight data of an item placed on the scale. The processor, which is connected to the reader, scale, and alarm indicator, is configured to access the read data and the measured weight data, to determine based on the read data an expected weight of the item, to compare the expected weight and the measured weight data, and to conditionally activate the alarm indicator if the expected weight and the measured weight data differ by at least a threshold amount.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims priority to U.S. Patent Application No. 60/714,543, entitled “RFID Weight Audit,” filed on Feb. 28, 2005, which is hereby incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD  
       [0002]     This disclosure relates generally but not exclusively to data readers such as optical code readers or RFID (radio frequency identification) readers, and more particularly, to object tracking using data readers.  
       BACKGROUND INFORMATION  
       [0003]     An RFID system typically employs at least two components: a “transponder” or “tag,” which is attached to the physical item to be identified, and an “interrogator” or “reader,” which sends an electromagnetic signal to the transponder and then detects a response. A typical tag stores useful information such as an identification code for the item to which it is attached. A typical reader emits an RF (radio frequency) signal that is received by the tag after the tag comes within an appropriate range. In response to the signal from the reader, the tag sends back to the reader a modulated RF signal containing the tag&#39;s information. The reader detects this modulated signal and can identify the tag by demodulating and decoding the received signal. After identifying the tag, the reader can either store the decoded information or transmit the decoded signal to a computer.  
         [0004]     The tag used in an RFID system may be either “passive” or “active.” A passive tag can be a simple resonant circuit, including an inductive coil and a capacitor. Passive tags are generally powered by the carrier signal transmitted from the reader. Active tags, on the other hand, generally include transistors or other active circuitry, and require their own battery source. Moreover, a tag&#39;s memory may be writable, and an RFID reader may transmit data to an RFID tag to overwrite the tag&#39;s memory.  
       SUMMARY OF THE DISCLOSURE  
       [0005]     According to one embodiment, a method reads data encoded on a pallet loaded with bulk articles and determines, based on the data, an expected weight of the pallet and bulk articles. The method weighs the pallet and bulk articles, thereby generating a measured weight, and compares the expected weight and the measured weight. The method conditionally issues a signal if the expected weight and the measured weight differ by at least a threshold amount.  
         [0006]     According to another embodiment, a method moves a data reader within a reading range of a container loaded with articles, reads data encoded on the container by use of the data reader, and determines, based on the data, an expected weight of the container and articles. The method moves a scale underneath the container, weighs, by use of the scale, the container and bulk articles, thereby generating a measured weight, and compares the expected weight and the measured weight. The method conditionally issues a signal if the expected weight and the measured weight differ by at least a threshold amount.  
         [0007]     According to another embodiment, a mobile device comprises a data reader, a scale, an indicator, and a processor. The data reader is capable of reading data encoded on an item within a reading zone, thereby generating read data, wherein the mobile device is positionable such that the item is within the reading zone. The scale generates measured weight data of an item placed on the scale, wherein the mobile device is positionable such that the item is on the scale. The processor, which is connected to the data reader, the scale, and the indicator, is configured to access the read data and the measured weight data, to determine based on the read data an expected weight of the item, to compare the expected weight and the measured weight data, and to conditionally activate the indicator if the expected weight and the measured weight data differ by at least a threshold amount.  
         [0008]     According to yet another embodiment, a device comprises a data reader, a scale, an indicator, and a processor. The data reader is capable of reading within a reading zone data encoded on a pallet loaded with bulk articles, thereby generating read data. The scale generates measured weight data of the pallet and any items loaded on the pallet when the pallet is placed on the scale. The processor, which is connected to the data reader, the scale, and the indicator, is configured to access the read data and the measured weight data, to determine based on the read data an expected weight of the pallet and its loaded items, to compare the expected weight and the measured weight data, and to conditionally activate the indicator if the expected weight and the measured weight data differ by at least a threshold amount.  
         [0009]     Details concerning the construction and operation of particular embodiments are set forth in the following sections with reference to the below-listed drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a drawing of a forklift, according to one embodiment.  
         [0011]      FIG. 2  is a drawing of a pallet, according to one embodiment.  
         [0012]      FIG. 3  is a block diagram of a system according to one embodiment.  
         [0013]      FIG. 4  is a block diagram of a system according to another embodiment.  
         [0014]      FIG. 5  is a diagram depicting a sequence of steps in the handling of the pallet of  FIG. 2 , according to one embodiment.  
         [0015]      FIG. 6  is a flowchart of a method according to one embodiment. 
     
    
     DETAILED DESCRIPTION OF EMBODIMENTS  
       [0016]     With reference to the above-listed drawings, this section describes particular embodiments and their detailed construction and operation. The embodiments described herein are set forth by way of illustration only. Those skilled in the art will recognize in light of the teachings herein that variations can be made to the embodiments described herein and that other embodiments are possible. No attempt is made to exhaustively catalog all possible embodiments and all possible variations of the described embodiments.  
         [0017]     For the sake of clarity and conciseness, certain details of components or steps of certain embodiments are presented without undue detail where such detail would be apparent to those skilled in the art in light of the teachings herein and/or where such detail would obfuscate an understanding of more pertinent aspects of the embodiments.  
         [0018]     As one skilled in the art will appreciate in view of the teachings herein, certain embodiments may be capable of achieving certain advantages, including by way of example and not limitation one or more of the following: (1) better tracking of items; (2) earlier detection of error conditions in item handling; (3) labor saving by, for example, facilitating weighing, data reading, and audit operations during normal item handling and transport operations; and (4) deterrence of theft and encouragement of more careful item handling. These and other advantages of various embodiments will be apparent upon reading the following.  
         [0019]      FIG. 1  is depicts a forklift  100 , according to one embodiment. The forklift  100  is useful to lift and transport heavy items, such as a pallet loaded with bulk (i.e., heavy or numerous or both) items. The forklift  100  comprises a cab section  105  and a mast  110 . A movable element  120  moves vertically in the middle of the mast  110 . Attached to the movable element  120  are two forks  130 .  
         [0020]     Between the moveable element  120  and the forks  130  is a scale  140 , which can weigh a pallet, container, or other load on the forks  130 . For example, the scale  140  may be a forklift truck scale manufactured by Avery Weigh-Tronix, LLC, Fairmont, Minn., such as its model QTLTSC scale.  
         [0021]     The forklift  100  is also equipped with a data reader  150 , which is preferably an RFID reader but may be a data reader of any type, such as an optical code reader (e.g., bar code). The data reader  150  is preferably positioned on the front of the forklift  100  facing forward to enable it to read data from a pallet, container, load, or other item on the forks  130 . For reading pallets, the data reader  150  is preferably positioned low, such as below the movable element  120  and/or the scale  140 .  
         [0022]     The data reader  150  is electrically connected to a computer or other data processor (not shown) on the forklift  100  or a remote computer. Alternatively, the computer may be integrated within the data reader  150 . The computer may display data on an electronic display  320  and/or may communicate the data wirelessly to another computer, such as a central computer in a warehouse, store, or other setting in which the forklift  100  operates.  
         [0023]      FIG. 2  depicts a pallet  200 , according to one embodiment. The pallet  200  comprises a number of top boards  210 , support members  220 , and bottom boards  230 . The support members  220  are spaced apart such that the forks  230  of the forklift  200  fit between the support members  220  to lift the pallet  200  and its contents or load.  
         [0024]     The pallet  200  also has placed on it a tag  240 , such as a code or identification tag, which is preferably placed on or near a side or sides of the pallet  200  that is faced by the forklift  100  during a lifting operation.  FIG. 2  shows several alternative locations for the tag  240 , which may be placed on the top or bottom of a top or bottom board  210  or  230 , or the end or either side of a support member  220 , for example. Depending on the range and spatial constraints of the data reader, proximity of the tag  240  to the data reader may be more or less important. When the tag  240  is an optical code, and the data reader is an optical code reader, then close proximity and a facing orientation of the tag  240  toward the reader is important. For an RFID reader, depending on its reading range and orientation or polarization sensitivity, any RFID tag  240  placed anywhere on the pallet  200  may be acceptable. Nonetheless, there is typically some benefit in terms of signal strength and thus reading reliability to have the tag  240  well placed for optimum reading.  
         [0025]      FIG. 3  is a functional block diagram of a system  300  according to one embodiment. The system  300  comprises a scale  140 , a data reader  150 , a processor  310 , and a number of other components connected to the processor  310 . One embodiment of the scale  1 . 40  was described above as part of the forklift  100  ( FIG. 1 ). Alternatively, the scale  140  may be a generally fixed, non-mobile floor scale, or any other type of scale or weighing means. The scale  140  generates an electrical signal that represents the weight or mass of an object or set of objects.  
         [0026]     The data reader  150  in this embodiment is an RFID reader comprising an antenna  160 , a transceiver  170 , a decoder  180 , and a controller  190 . The antenna  160  may be any suitable antenna that can transmit and receive electromagnetic signals within a reading volume. Typical RFID systems operate in the following frequency bands: 125-134 kHz (kiloHertz or thousands of cycles per second), 13.56 MHz (megaHertz or millions of cycles per second), UHF (ultra high frequency) (400-930 MHz), 2.45 GHz (gigaHertz or billions or cycles per second), and 5.8 GHz. The antenna  160  is typically chosen for a desired performance in one or more of those bands. The transceiver  170  generates an activation/interrogation signal and receives response(s) from one or more RFID tags. The transceiver  170  typically includes a modulator, filter(s), and amplifiers for transmission, as well as an amplifier, demodulator and filter(s) for reception. The transceiver  170  also typically includes a frequency synthesizer or RF oscillator shared by both the transmission and reception circuitry. This data reader  150  also comprises a decoder  180 , which decodes a demodulated signal supplied from the transceiver  170  to determine the data transmitted by the RFID tag(s). Alternatively, the function of the decoder  180  may be incorporated within the processor  310  rather than as part of the data reader  150 . This data reader  150  also comprises a controller  190  that controls the operation of the transceiver  170  and the decoder  180 . The controller  190  also provides an interface to the processor  310  from the data reader  150  for setup, status, command, control, and the like. The data reader  150  or just the antenna  160  may be mobile, removable, handheld, tethered by an electrical cable, etc.  
         [0027]     The processor  310  may be any form of processor and is preferably a digital processor, such as a general-purpose microprocessor or a digital signal processor (DSP), for example. The processor  310  may be readily programmable; hard-wired, such as an application specific integrated circuit (ASIC); or programmable under special circumstances, such as a programmable logic array (PLA) or field programmable gate array (FPGA), for example. Program memory for the processor  310  may be integrated within the processor  310 , permanently connected separately from the processor  310 , or externally removable. The processor  310  executes one or more programs to control the operation of the other components, to transfer data between the other components, to associate data from the various components together (preferably in a suitable data structure), to perform calculations using the data, to otherwise manipulate the data, and to present results and significant conditions to the user or to other equipment. For example, the processor  310  preferably determines an expected weight for an item or set of items based on the data read from one or more RFID tags associated with the item or set of items, compares that expected weight to the weight as measured by the scale  140 , and issues a signal (e.g., raises an alarm) or takes other actions based on that comparison, as described in greater detail below with reference to the flowchart shown in  FIG. 5 .  
         [0028]     Connected to the processor  310  are a display  320 , a speaker  330 , a network interface  340 , a user input device  350 , and a memory  360 . The display  320  may display such information as measured weight; data, such as identification data, read from the RFID tag(s), alarm conditions, such as when the measured weight does not match the expected weight for the item; pickup and drop-off instructions, and any variety of status information. The speaker  330  may be activated to audibly alert the user or other persons of an alarm condition or for other purposes.  
         [0029]     The network interface  340  may be a plug-in port or a wireless communications point. In one preferred embodiment, the network interface is a wireless network interface operating in accordance with a standard wireless network protocol such as the Institute of Electrical and Electronics Engineers (IEEE) 802 standards (e.g., IEEE 802.11 standard for wireless local area networks (WLAN)). In one embodiment, the processor  310  accesses expected weight data stored on another computer, such as a central computer, for comparison with the weight measured by the scale  140 , via the network interface  340 . The processor  310  may also send measured weight data, data read by the data reader  150 , and/or alarm conditions to another computer via the network interface  340 .  
         [0030]     The user input device  350  may be any device used by a user to input data or commands to the processor  310 . Examples of the user input device  350  include keypads, keyboards, pointing devices (e.g., mouse, joystick, trackball), buttons, and a touch screen. The memory  360  may store programs executed by the processor  410 , expected weight data for a set of items, and/or other data. The memory  360  may be permanent or removable.  
         [0031]     As an alternative to what is illustrated in  FIG. 3 , the data reader  150  may operate according to another principle different from RFID. For example, the data reader  150  may be an optical code reader that reads information encoded on an optical code on the item or set of items placed on or near the scale  140 . The most common example of an optical code is a bar code; thus, according to one embodiment, the tag  240  on the pallet  200  or on the items on the pallet  240  is a bar code, and the data reader  150  is a bar code reader.  
         [0032]     As yet another alternative, the system  300  may comprise multiple different types of data readers, such as a combined RFID reader and bar code reader. Such a multiple-technology reader is described, for example, in U.S. Pat. No. 6,415,978, entitled “Multiple Technology Data Reader for Bar Code Labels and RFID Tags,” which is incorporated herein by reference. One example of a multiple-technology reader for use in a weight-audit system is illustrated in  FIG. 4 . In that figure, the weight-audit system  400  is a movable system (preferably configured on a forklift, such as the forklift  100  ( FIG. 1 ) or other mobile item-handling device) for tracking inventory movable to a plurality of locations. The system  400  includes an RFID reader  410  having both a fixed antenna  420  and a portable handheld antenna  430 . The combination of the RFID reader  410  and one of the antennas  420  or  430  is similar to the data reader  150  shown in  FIG. 3 . An advantage of the dual-antenna design is that the fixed antenna  420  requires less manual intervention in most situations, especially when the RFID tags are well placed to facilitate reading by the fixed antenna  420 , whereas the handheld antenna  430  provides flexibility for the user to position that antenna to read otherwise hard-to-read places for tags. In addition, the system  400  comprises a portable handheld barcode scanner  440 , which may be fixed or handheld. Although RFID has some advantages over bar codes in many settings (e.g., “facing” of the reader to the tag may not be require or may be less demanding; the requirements or distance, speed, direction and orientation are generally relaxed; multi-tag reading can be more efficient; and the storage capabilities of RFID tags can be taken advantage of), flexibility, economy, and speed of deployment can be enhanced by providing the capability to work with bar codes. A scale  450  may be any weighing means but is preferably a commercial legal-for-trade scale or electronic load-cell, of which many are known in the pallet-weighing and related arts. A fixed station terminal  460  is also part of the weight-audit system  400 . The fixed station terminal  460  is a computer comprising, for example, the processor  310  and associated peripherals as shown in  FIG. 3 . The fixed station terminal  460  is a portable computer that may be ruggedized for use in an industrial or warehouse setting. Connected to the fixed station terminal  460  is a WLAN adaptor  470  to enable wireless communication. The fixed station terminal  410  interfaces with a host computer  480  either by cable plug-in or wirelessly via the WLAN adaptor  470 . Finally, the system  400  comprises a warning light  490  and/or an alarm  495  to alert a user of missing inventory items from a pallet or defective RFID tag(s) on an RFID-tagged pallet.  
         [0033]      FIG. 5  is a set of drawings pictorially depicting a sequence of steps in the handling of the pallet  200 , according to one embodiment. More specifically,  FIG. 5  depicts an RFID-based weight audit in a supply-chain application to track inventory at a plurality of locations. The sequence of events in this audit is depicted from left to right in the drawing. To begin, a user locates at an origination location an empty pallet  200 , which may have one or more RFID tags  240  attached to it, and loads the pallet  200  at the origination location with inventory items to provide a loaded pallet. The audit then proceeds using a first vehicle movable to a number of pallet origination locations. The first vehicle may be the fork lift  100 , a lift truck, a pallet truck, a cart or any material handling device. The first vehicle includes a scale and an RFID reader, etc., as depicted for example in FIGS.  3  or  4 . (Hereafter the reference numbers appearing in  FIG. 1-3  will be used for the sake of concreteness.) The RFID reader  150  sends and receives RF signals to/from RFID tags  240  located on the pallet  200  and/or the inventory items positioned on the pallet  200 . The user next weighs the loaded pallet  200  and encodes that weight information on the RFID tag  240  that is to be attached to the loaded pallet or already attached to the loaded pallet. That is preferably accomplished by the user reading the pallet weight from the scale  140  and encoding and writing that weight information on the RFID tag  240  by using the RFID reader  150 . The loaded pallet  200  of inventory items is then shipped to one of a plurality of destination locations. At intermediary steps, the loaded pallet  200  may be moved at the origination location before shipping or during shipping merged-in transit with other pallets. At any intermediary step or when the loaded pallet  200  reaches a destination location, a second vehicle movable to a plurality of destination locations and including a scale  140 , an RFID reader  150 , and other equipment interrogates the RFID tags  240  located on the pallets  200  and/or the inventory items positioned on the pallet  200  and weighs the items. For example, at the destination location the received pallet  200  is weighed and interrogated using the second vehicle. If the weight of the pallet  200  of inventory items has changed, then a warning light, flashing display, and/or an audible alarm can be activated to indicate to the user there is a problem. The user can then undertake an appropriate business strategy to deal with the problem. In due course, the pallet  200  cam be moved to a pickup location or a storage location, the items can be de-boxed, or another final action can be taken.  
         [0034]     A change of weight might indicate theft, mislocation of one or more items, or other mishandling. By facilitating more convenient, more frequent, earlier, and more precise detection of those problems, the systems and methods described herein can enable a business to better respond to those problems, thereby lessening their impact on the business.  
         [0035]      FIG. 6  is a flowchart of a method  600  according to one embodiment. The method  600  is performed at the destination location or other location at which an audit operation is needed. The method  600  will be described herein with reference to the devices and structures depicted in  FIGS. 1-3 , but it should be understood that the method  600  is not limited to practice with those devices and structures. For example, reference to a pallet in  FIG. 6  and its following description is simply by way of example; the “pallet” could just as well be a crate, barrel, container of any type, item packaged or unpackaged, or collection of items.  
         [0036]     To begin, the method  600  moves (step  610 ) the data reader  150  within a reading range (or volume) of the pallet  200 . This moving step  610  may occur when the data reader  250  on the forklift  100  or other mobile platform in maneuvered within proximity of the pallet  200 . Alternatively, the moving step  610  may occur when the pallet  200  is transported and placed within the reading range of a stationary data reader  150 . Thus, the moving step may entail moving one or both of the data reader  150  and/or the pallet  200  such that the pallet  200  is within a reading range of the data reader  150 . Once within range, the method reads (step  620 ) the encoded data on the pallet  200  or its loaded items. The data may be encoded in the RFID tags  240 , in optical codes, or by other means. The data may be encoded on the pallet, container, or other carrier, or it may alternatively or additionally be on each item loaded on the pallet or the like. After reading the data, the method  600  determines (step  630 ) an expected weight for the pallet. The determining step  630  may be performed in various ways. For example, the data read in step  620  may comprise the expected weight. As another example, utilizing identification data read in step  620 , the determining step  630  can look up a corresponding expected weight in either a local database or a database on a remote computer. In either case, an advantage of pallet-based encoding is that one read provides the data for the entire pallet. If the data is encoded at a finer level (e.g., item level), then the data reader  150  or the processor  310  may need to sum the multiple weights for each item to get a total weight for the collection.  
         [0037]     The method  600  also moves (step  640 ) the scale  140  underneath the pallet  200 . As with the moving step  610 , the moving step  640  does not necessarily imply motion of the scale  140  with respect to a stationary pallet  200 . For example, by using a stationary scale and by moving the pallet  200  onto the scale, the moving step  640  may also be accomplished. After the moving step  640 , however accomplished, the method  600  weighs (step  650 ) the pallet and compares (step  660 ) the expected weight to the measured weight. The method  600  can then issue (step  670 ) one or more signals as necessary, such as if the measured weight and the expected weight deviate by more than a predetermined threshold. Such a threshold hold may be based on the precision of the scale  140  or business considerations (e.g., how much of a deviation constitutes a financially significant difference given the cost of responding to the alarm and the value of the item). Different items may have different thresholds, and threshold data may be stored in a database with other item data. The signal may be raised locally (e.g., at the forklift  100 ), remotely, or at both locations. The signal may be a message on a display screen, a light that turns on, a light that blinks, a sound, or any sort of alarm.  
         [0038]     The steps of the method  600  may be performed in an order different from what is illustrated, or steps may be performed simultaneously. For example, simultaneously weighing and data reading may provide an efficient sequence. Performing those steps just before, after, or during movement or other necessary handling of the items may also efficiencies. The method  600  may perform other steps not illustrated, such as writing the newly measured weight on the RFID tag  240 , storing the measured weight and other tracking data, etc.  
         [0039]     The algorithms for operating the methods and systems illustrated and described herein can exist in a variety of forms both active and inactive. For example, they can exist as one or more software or firmware programs comprised of program instructions in source code, object code, executable code or other formats. Any of the above can be embodied on a computer-readable medium, which include storage devices and signals, in compressed or uncompressed form. Exemplary computer-readable storage devices include conventional computer system RAM (random access memory), ROM (read only memory), EPROM (erasable, programmable ROM), EEPROM (electrically erasable, programmable ROM), flash memory and magnetic or optical disks or tapes. Exemplary computer-readable signals, whether modulated using a carrier or not, are signals that a computer system hosting or running a computer program can be configured to access, including signals downloaded through the Internet or other networks. Concrete examples of the foregoing include distribution of software on a CD ROM or via Internet download. In a sense, the Internet itself, as an abstract entity, is a computer-readable medium. The same is true of computer networks in general.  
         [0040]     The terms and descriptions used herein are set forth by way of illustration only and are not meant as limitations. Similarly, the embodiments described herein are set forth by way of illustration only and are not the only means of practicing the invention. Those skilled in the art will recognize that many variations can be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the invention should therefore be determined only by the following claims (and their equivalents) in which all terms are to be understood in their broadest reasonable sense unless otherwise indicated.