Patent Publication Number: US-2007119926-A1

Title: Radio frequency identification (RFID) based location tracking system in an airport environment

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      The present application is a continuation of U.S. patent application Ser. No. 11/025,961, filed Jan. 3, 2005, which claims the benefit of U.S. Provisional Application No. 60/620,909, filed Oct. 22, 2004, both of which are hereby incorporated by reference herein in their entirety. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to automated and semi-automated identification and tracking of items in an airport environment using radio frequency identification (RFID) technology.  
      2. Background Art  
      An RFID tag may be affixed to an item whose presence is to be detected and/or monitored. The presence of an RFID tag, and therefore the presence of the item to which the tag is affixed, may be checked and monitored by devices known as “readers.” 
      Airports are required to track large quantities of items/assets, including passenger baggage. These items are checked into the airport by the passengers, and then are transported to the corresponding aircraft. What is desired is the ability to generate an automated manifest of assets being loaded into aircraft transports and containers. Current procedures require the use of manual labor to log each asset as it is being transported and loaded. The ability to identify locations of items within an aircraft or container is not possible with existing systems.  
     BRIEF SUMMARY OF THE INVENTION  
      Methods, systems, and apparatuses for automatically and semi-automatically tracking and managing items with changing locations in an airport environment are described. A radio frequency identification (RFID) tag is used with a material tracking system to enable the identification and locating of aviation assets, such as baggage and cargo. For example, passive (e.g., non-battery) RFID tags are attached to an aviation asset. Antennas with stationary coverage areas are placed at locations where monitoring of assets is necessary. A local controller/RFID reader uses the antennas to communicate with the passive RFID tags to determine the identity and location of the asset.  
      Objects to be tracked are transported by moving conveyor belts, and unit load devices (ULD) are positioned adjacent to the conveyor belts in the stationary coverage area of the at least one antenna. The local reader coupled to the antenna reads the tags as the objects associated with the tags enter the coverage area of the antenna.  
      An object management system (OMS) receives information regarding already read tags from the reader, and stores the information. An operator feedback unit (OFU) enables an operator to interact with the reader. Operators follow defined procedures to ensure objects are both being read by the RFID system and being placed into the appropriate ULD.  
      Implementation of the RFID conveyor baggage handling system of the present invention can be based on a “last seen” logic. In other words, a bag is considered “assigned to” a particular ULD as soon as the reader associated with that ULD reads the bag and until such time as another subsequent reader reads the same bag.  
      These and other objects, advantages and features will become readily apparent in view of the following detailed description of the invention.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES  
      The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention.  
       FIG. 1  shows an example layout of a lateral conveyor with unit load devices (ULDs) position alongside, according to an example embodiment of the present invention.  
       FIG. 2  shows an antenna of a conveyor system reader station having a coverage area adjacent to a conveyor that has an upper conveyor belt and lower conveyor belt, according to an example embodiment of the present invention.  
       FIG. 3  shows an empty, enclosed ULD positioned with a door open in front of a conveyor system reader station, according to an example embodiment of the present invention.  
       FIG. 4  shows a curtained ULD, having opposing first and second sides, each covered by a respective curtain.  
       FIG. 5  shows the ULD of  FIG. 3  after being filled with baggage, according to an example embodiment of the present invention.  
       FIGS. 6A and 6B  show plan views of example coverage configurations with respect to conveyors for empty and full ULDs, respectively, according to an example embodiment of the present invention.  
       FIG. 7  illustrates an example read zone marking scheme, that includes a plurality of reading stations, according to an example embodiment of the present invention.  
       FIG. 8  shows read areas associated with each of six readers on a lateral conveyor, according to an example embodiment of the present invention.  
       FIG. 9  shows a bag being removed from an active read zone of a reader, and carried behind ULDs to another reader, according to an example embodiment of the present invention.  
       FIG. 10  shows an example RFID system architecture to be used with conveyor systems, according to an example embodiment of the present invention.  
       FIG. 11  shows an example flowchart providing baggage handling logic for a conveyor system, according to embodiments of the present invention.  
       FIG. 12  shows a bag being placed in a ULD in an active read area of a reader, according to an example embodiment of the present invention.  
       FIG. 13  shows a baggage handler using a conveyor to move a bag to an appropriate ULD before placing it inside.  
       FIG. 14  shows a block diagram for a reader, according to an embodiment of the present invention.  
       FIG. 15  shows an example flowchart providing steps for operating a conveyor system, according to an example embodiment of the present invention.  
       FIG. 16  shows a flowchart providing an example functional test procedure for a conveyor system, according to embodiments of the present invention. 
    
    
      The present invention will now be described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears.  
     DETAILED DESCRIPTION OF THE INVENTION  
      Introduction  
      As described above, airports are required to track large quantities of items/assets, including passenger baggage. These items are checked into the airport by the passengers, and then are transported to the corresponding aircraft. What is desired is the ability to generate an automated manifest of assets being loaded into aircraft transports and containers. Current procedures require the use of manual labor to log each asset as it is being transported and loaded. The ability to identify locations of items within an aircraft or container is not possible with existing systems.  
      RFID enabled systems, apparatuses, and methods of the present invention allow for the automated collection of asset identities, and for location association for these assets. The present invention is the first to integrate RFID technology into an existing aviation process. The ability for the aviation industry to identify and locate assets in the transportation of goods, according to embodiments of the present invention, reduce cycle times, such as when security procedures require the removal of assets from aircraft.  
      In an example embodiment, a passive ultra-high frequency (UHF) radio frequency identification (RFID) tag is used with a material tracking system to enable the identification and locating of aviation assets in an airport environment. Passive (e.g., non-battery) RFID tags are attached to an aviation asset. Antennas are placed at locations where monitoring of assets is necessary. A local controller/RFID reader use the antennas to communicate with the passive RFID tags to determine the identity and location of the asset.  
      Example embodiments of the present invention are described below with respect to an aviation baggage tracking environment. It is noted that embodiments of the present invention can be adapted to the tracking of any types of objects in a conveyor system, including baggage.  
      Terms and Abbreviations  
      OMS=Object Management System (OMS). An OMS keeps track of objects being transported within an environment.  
      BMS=Baggage Management System (Bag Manager). A system that keeps track of baggage as being transported through an airport. A BMS can include hardware, software, firmware, and any combination thereof. A BMS is an example of an OMS, where the objects being tracked include baggage.  
      HKIA=Hong Kong International Airport. An example airport at which embodiments of the present invention can be implemented.  
      ARS=Aviation Reader Station. An example of a reader described herein.  
      OFU=Operator Feedback Unit. An indicator device that provides one or more indications of reader station operation. Can include any number and any type of indicator devices, including lights, sounds, and display, etc. Also can include any type of operator input devices, including buttons, a keyboard, a mouse, etc.  
      HHT=Hand Held Terminal. A hand held mobile device, such as a palm pilot, handheld computer, etc.  
      ULD=Unit Load Device. Refers to containers, pallets and pallet nets. An example purpose of a ULD is to enable individual pieces of cargo to be assembled into standardized units to ease the rapid loading and unloading of aircraft, and to facilitate the transfer of cargo between aircraft having compatible handling and restraint systems.  
      “Conveyor system” refers to all types of systems for conveying objects, including conveyor belts, conveyors that transport hanging objects, etc. A conveyor system may include one or more conveyors. The conveyors may convey objects in any direction, including horizontally, vertically, and any direction in between. A “lateral” conveyor is an example conveyor type, and refers generally to horizontally disposed conveyors (e.g., a conveyor belt that conveys objects in a direction generally parallel to the ground).  
      Reader System Embodiments  
      Embodiments for RFID reader systems supporting conveyors in a baggage area of an airport are described. Baggage travels along the conveyors, and in ULDs, to and from various airport destinations, such as passenger baggage drop-off, passenger baggage pickup, and aircraft loading/unloading areas. One or more read areas (also referred to as read points, read zones, etc.) are designated along the conveyors. One or more readers are designated to cover each read area. Thus, each read area is dedicated to a specified area of a conveyor and is responsible for monitoring and tracking bags being loaded into/onto a ULD (i.e., any container type, pallet, etc.), or from a ULD, placed in front of it.  
      For instance, an example system may use ARS readers, where each ARS reader has multiple reader units (e.g., antennas) that each have a respective read area/coverage area. In such a system, an ARS reader can control multiple read points along one or more conveyors.  
      When a flight is scheduled to be loaded, an operator uses a computing device, such as a hand-held terminal (HHT), to initially configure the RFID system on the appropriate conveyor. ULDs are logically linked to the read areas, and the system is enabled to start building a bag manifest for the flight. The reader(s) and read area(s) are responsible for capturing bag information and transmitting it to the BMS. The BMS makes a determination of whether or not a particular bag is legal to load into the ULD where the information was captured, and relays this information to the operator via a feedback mechanism called an operator feedback unit, or OFU. One or more OFUs are associated with each read point of the conveyor system. In an example embodiment, at the conclusion of the loading process, an OFU can be reset (if needed) (e.g., a button is pressed on the OFU), and the information collecting process is complete.  
      Conveyor System RFID Coverage  
      Embodiments of the RFID conveyor system uses one or more readers at each station to successfully interrogate tags in a robust manner. The conveyor RFID system accounts for every bag that is loaded into a ULD.  
      Example conveyor RFID system embodiments of the present invention may be enhanced if the following conditions are adhered to, although in not all cases are they required:  
      (a) Appropriate reader radio frequency (RF) signal coverage is provided to each ULD to ensure that bags being placed into the ULD can be read.  
      (b) ULDs are positioned correctly in front of readers so that the reader antennas are directed/located in or near the middle of the ULD opening. In the case of a ULD requiring two antennas, the antennas can be configured in a variety of ways, including being equally spaced across the opening.  
      (c) Baggage handlers follow defined procedures to ensure bags are both being read by the RFID system and being placed into the appropriate ULD.  
      (d) A tag that is placed onto a bag is capable of being read (i.e. has not been removed or damaged, thus making it inoperable)  
      RFID Conveyor Coverage  
      ULD containers and conveyors pose a unique set of challenges with respect to RFID system implementation. For example, on conveyors, RFID tags can approach the reader from a number of directions that are not controlled by a user. Users walking directly in front of a reader antenna may reflect RFID energy onto conveyors thus causing additional unintended bag reads. The RFID coverage pattern of a particular reader can change, sometimes radically, as the loading process takes place.  FIG. 1  shows an example layout  100  of a lateral conveyor  102  with ULDs  104  position along the side (to right side in  FIG. 1 ). In an embodiment, in an example airport, a lateral conveyor system includes an upper and lower conveyor belt, each feeding bags in opposite directions.  
      Conveyor system reader antennas are normally aimed to provide maximum power to the area immediately in front of a ULD, while attempting to minimize any RFID power falling on the actual conveyor belts themselves.  FIG. 2  shows such a configuration, where an antenna  202  of a conveyor system reader station  200  has a coverage area  204  adjacent to a conveyor  102  having an upper conveyor belt  208  and lower conveyor belt  210 .  
      A difficulty arises when a ULD is placed in front of a lateral conveyor. Although ULDs can have a number of different forms and sizes, container-type ULDs can be classified into two main categories: (1) enclosed, meaning loading is performed through a single opening (e.g., a door) on a side of the container, and (2) open, meaning that there are two open sides (typically opposing sides) that utilize curtains to cover the openings rather than metal or hard plastic coverings. Loading of bags can occur through either open side.  
       FIG. 3  shows an empty, enclosed ULD  104   a  (e.g., made of aluminium) positioned with a door  304  open in front of a conveyor system reader station  200 . Reader station  200  directs a read signal at ULD  104   a  to read tags attached to bags held within. As shown in  FIG. 3 , the interior of ULD  104   a  tends to reflect a substantial amount of energy  306  back past reader antenna  202  and onto conveyor  102 , thus allowing reader station  200  to sometimes erroneously read or “see” nearby bags that are not contained in ULD  104   a , such as bags  308  on one or both of belts  208  and  210 . The actual number of bags  308  seen depends on a number of factors, such as size of ULD  104   a , proximity to reader station  200 , and an angle of ULD  104   a  relative to conveyor  102 .  
       FIG. 4  shows a curtained ULD  104   b , having first and second sides  402  and  404 , each covered by a respective curtain. The curtains are partially or fully transparent to the read signal transmitted by antenna  202 . Thus, sides  402  and  404  of ULD  104   b  are considered “open” with respect to RF energy, as there are no sides (e.g., made of metal) to block or reflect RF energy. Curtained ULD  104   b , being open on sides  402  and  404 , does not exhibit the undesired energy reflection caused by enclosed ULD  104   a  of  FIG. 3 . Instead, energy  406  passes directly through, or is reflected through curtained ULD  104   b.    
      As ULD  104   a  of  FIG. 3  is filled with baggage, such as shown in  FIG. 5 , bags  502  inside ULD  104   a  tend to absorb RF energy  504  being directed into and reflected around the interior of ULD  104   a . Thus, less energy is reflected out of a filled ULD  104   a , and RF coverage with respect to conveyor  102  in  FIG. 5  decreases to the point where coverage area  506  is similar to coverage area  204  of  FIG. 2 .  
      Thus, the actual RF coverage over conveyor  102  is dynamic, depending on the type of ULD  104 , and how full is the ULD  104 .  FIGS. 6A and 6B  show plan views of example coverage configurations with respect to conveyors  102  for empty ULDs  104   a  and full ULDs  104   a , respectively. As shown in  FIG. 6A , antennas  202  emit RF energy to ULDs  104   a , over a respective coverage area/volume  602 . Furthermore, as shown in  FIG. 6A , because ULDs  104   a  are empty, energy  604  is reflected back, over conveyor  102 . In contrast, as shown in  FIG. 6B , where ULDs  104   a  contain baggage, substantial RF energy is not reflected.  
      Marking of Read Areas/Positioning of ULDs  
      In order to minimize unwanted bag reads, each conveyor has read areas that are clearly marked, with the expectation that tags on bags entering a read area may be captured by the corresponding reader.  FIG. 7  illustrates an example read area marking scheme  700 , that includes a plurality of reading stations  702   a - f . Each of reading stations  702   a - f  has corresponding reader marking lines  706  applied thereto, to show a read area corresponding to the respective reading station  702 . A coverage area for each reading station  702  is between the respective reader marking lines  706 . Thus, for example, reader marking lines  706  may be applied to the floor, etc., of each reading station  702  to show the corresponding read area.  
      Furthermore, each reading station  702   a - f  can optionally be marked to identify the reading station. For example, a large number identifying each reading station  702  can be used, which can be applied (e.g., painted) directly below each reader, such as on the floor near a curb  704 . For example, each of reading stations  702   a - f  in  FIG. 7  is marked respectively with a  1 ,  2 ,  3 ,  4 ,  5 , and  6  identifying number. At each location, the identifying number can be placed at a center line of the coverage areas for the antenna, for example. The identifying number serves not only to identify the reader to a baggage handler, but serves as an alignment marker for a ULD  104 . When ULDs  104  are positioned at each reader  702 , the center of the ULD  104  lines up with the identifying number on the floor.  
      When a ULD  104  requires two readers, a first reader can be a fixed reader  710  a second reader can be a moveable reader  708 . A moveable reader  708  is a reader that typically has a range of conveyor  102  along which it can be moved. The first and second readers can be positioned to maximize effective coverage of the ULD  104 . For example, the opening of the ULD  104  can be positioned so that a fixed reader  710  is placed one-third of the distance from a side of the opening of the ULD  104 , while a moveable reader  708  is placed one-third of the distance from the other side of the opening of the ULD  104 . Thus, in this manner, two readers can be located between the sides of the ULD  104  to effectively read the ULD  104 .  
      Conveyor Read Areas  
      Implementation of the RFID conveyor baggage handling system of the present invention can be based on a “last seen” logic. In other words, a bag is considered “assigned to” a particular ULD as soon as the reader associated with that ULD reads the bag and until such time as another reader reads the same bag.  FIG. 8  shows read areas  802  and  804  associated with each of readers  702   a - f  on conveyor  102 . For simplicity, RF signal coverage in front of and into ULDs  104  in  FIG. 8  is not explicitly shown, while the area pertaining to the conveyor  102  is shown.  
      In the example of  FIG. 8 , conveyor  102  is shown as having a series of “active” read areas  802   a - f  alternating with “implied” read areas  804   a - f . As a bag travels  810  along conveyor  102 , it will always be in-either an active read area  802   a - f  or an implied read area  804   a - f.    
      Active read areas  802  are those areas covered by a reader  806  (either fixed or moveable), whereby a tag (e.g., attached to a bag  810 ), upon entering the active area, has the potential of being read. Typically, a RFID coverage area for conveyor  102  is configured so that reads of bags  810  on the conveyor belt are kept to a minimum. Because of the nature of RFID, however, bags may occasionally be read on the conveyor (which may be a belt, for example) due to the location of where the operator is standing (e.g., a reflection), how full the ULD is, where the bag is on the conveyor, and where the ULD was parked relative to the reading antenna.  
      Implied read areas  804  are areas not covered by a reader  806 . Bags  810  in an implied read area  804  cannot be read by an antenna. Thus, by using “last seen” tracking logic, bag  810 , when in an implied read area  804 , can be inferred as belonging to the last reader  806  that “saw” (i.e., read) it. Bag  810  will continue to be “owned” or tracked by the last reader  806  until it is “seen” (i.e., read) by a new reader  806 . Therefore, in the case that bag  810  is traveling on a belt of conveyor  102 , and that bags  810  travel in one direction on a particular belt, the implied read area  804  of a particular reader  806  is the belt area in the direction of belt travel (i.e., downstream of the reader), in the portion of the belt from the end of the active read area  802  of the reader to the beginning of the active read area  802  of the next reader.  
      Thus, in an embodiment, a particular bag can be tracked along a conveyor (e.g., by a user and/or computer system) having a known configuration (e.g., location of active read areas, location of active implied read areas, speed and timing of conveyor, etc.), by determining the presence of the bag in an active read area, and implying its location as it moves through implied read areas, until its updated location is determined in subsequent active read areas, etc.  
      In an embodiment, once a bag leaves an active read area  802 , non-read areas are implicitly associated with the reader until the bag moves into another active read area. An example of this is illustrated in  FIG. 9 . In  FIG. 9 , a bag  910  is present in an active read area  802   a , where it is read by reader  806   a . Bag  910  is then removed from active read zone  802   a  of reader  806   a , and is carried behind ULDs (not shown in  FIG. 9 ) to reader  806   e . Thus, in  FIG. 9 , bag  910  is associated with reader  806   a  until read by reader  806   e  in active read zone  802   e.    
      RFID baggage (or other object) tracking systems according to embodiments of the present invention can be configured in a variety of ways. In an example embodiment, similar to the configuration shown in  FIG. 8 , the RF coverage for a conveyor is configured so that when ULDs are positioned in front of readers, six non-overlapping reader areas are established. However, the present invention is not limited to six reader areas, and can have any number of one or more reader areas, any number of conveyors, etc  
      Example Block Diagram  
       FIG. 10  shows an example RFID system architecture  1000  in support of the conveyor system embodiments described above. Architecture  1000  is shown for illustrative purposes, and is not limiting. Architecture  1000  can be modified in various ways, as would be understood by persons skilled in the relevant art(s). These modifications are within the scope and spirit of the present invention. For example, architecture  1000  can be applied to environments other than the baggage management environment described below.  
      In the example embodiment of  FIG. 10 , each conveyor system will have two reader systems  1002   a  and  1002   b  installed. In  FIG. 10 , first reader system  1002   a  includes three antennas  1004   a - c , while second reader system  1002   b  includes three antennas  1004   d - f . Antennas  1004   a - c  are coupled to a baggage management system (BMS)  1008  through reader/local controller  1006   a , and antennas  1004   d - f  are coupled to BMS  1008  through reader/local controller  1006   b . In the current embodiment, antenna  1004   f  is optional, depending on the type of conveyor system being supported.  
      In alternative embodiments, any number of one or more reader systems  1002  may be present in an architecture  1000 , depending on the particular application. Furthermore, any number of one or more antennas  1004  may be present for each controller  1006 , depending on the particular application.  
      BMS  1008  is a system that keeps track of baggage (and/or other objects) as the baggage is being moved through an airport (or other location). BMS  1008  includes hardware, software, and/or firmware, including any combination thereof, to perform its functions. For example, BMS  1008  may be incorporated into a computer system. BMS  1008  includes one or more storage devices for storing location of bags, such as memory components, disc-based storage, magnetic storage devices, optical storage, etc. Furthermore, BMS  1008  can include a user interface, such as including a keyboard, display, graphical user interface (GUI), pointing device, and/or other visual and/or audio indicators, for interacting with the BMS as needed.  
      BMS  1008  receives tag information from, and outputs control information to controllers  1006   a  and  1006   b . Controllers  1006   a  and  1006   b  cause antennas  1004   a - 1004   c  and  1004   d - 1004   f , respectively, to transmit read signals to tags attached to baggage. Antennas  1004   a - 1004   c  and  1004   d - 1004   f  receive tag responses, and transmit them to controllers  1006   a  and  1006   b , respectively. Demodulation of the received signals can occur at antennas  1004   a - f , or can be performed by controllers  1006   a  and  1006   b , depending on the particular system configuration. Thus, BMS  1008  uses controllers  1006   a  and  1006   b  to determine tags that are present at the read areas of antennas  1004 - 1004   f.    
      Each antenna  1004   a - f  is logically associated by BMS  1008  to a ULD  104 . In an example embodiment, each antenna  1004   a - f  has a separate transmit and receive side. To minimize signal loss, each side is serviced by a set of two cables. For example, LMR  400  low loss cable can be run from a respective reader  1002   a  and  1002   b  as far as possible, typically to the beginning of the service loops for any moveable readers. LMR  240  cable, which is more flexible, can be run for the remainder of the distance. However, the present invention is not limited to these particular antenna and cable implementations.  
      At least one interface, referred to as an operator feedback unit (OFU)  1010 , is present for an operator to interact with antennas  1004 . For example, in  FIG. 10 , OFUs  1010   a - c  are coupled to controller  1006   a , and OFUs  1010   d - f  are coupled to controller  1006   b.    
      In the example of  FIG. 10 , each OFU  1010  is shown including a red light indicator, a green light indicator, a yellow light indicator, a buzzer indicator, and a button. These are shown for illustrative purposes, and are not intended to limit the invention. An OFU  1010  can include any type of indicator/input-output device as described elsewhere herein, or otherwise known, as would be understood to persons skilled in the relevant art(s).  
      For example, a button on an OFU  1010  can be pressed to start/stop data capture associated with one or more antennas  1004 . Thus, an OFU  1010  can be used to initiate reading of tags in one or more read areas. For example, an OFU  1010  can be used to initiate reading of tags in a read area, in relation to a ULD  104  present in the read area. When a bag is placed into the ULD  104 , the tag associated with the bag is read, and the information is transmitted to BMS  1008 . BMS  1008  determines which antenna  1004  “saw”/read the tag. Based on this, BMS  1008  determines which ULD  104  is associated with the particular antenna  1004 , and triggers an indicator (e.g., light/buzzer or other) sequence at an appropriate OFU  1010  associated with the antenna  1004 . For example, the indicator indicates whether the bag was loaded into the proper ULD. After a ULD is completely loaded, a button on the respective OFU  1010  can be pressed to close the session and prevent any additional information from being recorded. An example OFU  1010  is described in further detail below.  
      Control Logic for ULD Baggage Handling  
      In an embodiment, each RFID reader  1002  on a conveyor system is equipped with an OFU  1010  which indicates through indicators, such as a series of lights, one or more buzzers, a display such as a light-emitting diode (LED), liquid crystal diode (LCD), cathode ray tube (CRT), etc., or other indicator, whether a bag that a reader  1002  has read belongs in the ULD associated with that particular reader.  
      The following table outlines feedback control logic supporting an OFU, according to an example embodiment of the present invention.  
                                                       Green   Red   Yellow   Buzzer               Light   Light   Light   State       Event   Status   Status   Status   (duration)   Remark                  “Off Duty” Mode (1)   Off   Off   On   Off   Same as “ULD Close”                           event       ULD   On   On   On   On (3 sec)   indicates ULD is       Registration (2)                   ready for loading       Press open ULD       button (3)       Load bag in   On   Off   On   On (1 sec)       correct ULD (4)       Load bag in   Off   On   On   On (3 sec)   indicates bag should       incorrect ULD (5)                   be loaded in a                           different ULD, or                           check with computing                           device       Press close ULD   Off   Off   On   Off       button (6)       System fault (7)   Flash   Flash   On   On (3 sec)   Inform supervisor,                           fallback to computing                           device                 (1) “Off duty mode” is indicated by the OFU when tag reading is not desired, such as when baggage is not being loaded into a ULD.            (2) “ULD registration” can be used to associate a particular ULD with an antenna, for example.            (3) “Press open ULD button”: An operator presses a button of the OFU (or otherwise interacts with the OFU) to logically open a ULD for loading of baggage, for example.            (4) “Load bag in correct ULD” is indicated when a read tag is approved by the BMS as being loaded into the proper ULD.            (5) “Load bag in incorrect ULD” is indicated when a read tag is determined by the BMS as not being loaded into the proper ULD. In such a situation, the bag should be put aside, or should be loaded into a proper ULD.          # Alternatively, the operator&#39;s computing device can be used to check, and correct if necessary, system configuration. In an example embodiment, the computing device communicates with the BMS, by either a wireless or wired connection.          (6) “Press close ULD button”: An operator presses a button of the OFU (or otherwise interacts with the OFU) to logically close a ULD for loading of baggage, for example.            (7) “System fault” may be indicated when a system problem occurs, to alert a system operator, as such.            In embodiments, OFUs may include any one or more of these features and/or alternative features, as desired for the particular application.             
 
      Conveyor System Baggage Handling Logic  
      This section describes baggage handling logic used to support successful reading of tagged bags going into ULDs, according to embodiments of the present invention. Reading of tags is highly dependant on a number of factors. Example conditions that can affect the speed or success of tags reading include:  
      (a) Tags placed on metal cases or other surfaces hostile to RFID environments;  
      (b) Tags read at an angle relative to the reader antenna;  
      (c) Persons standing between the reader and the tag;  
      (d) Location of the ULD relative to the antenna;  
      (e) Type of ULD;  
      (f) Damage to the tag; and  
      (g) Contents of bag being tracked.  
      Thus, to encourage a high read rate, loading procedures should be followed in a systematic and consistent manner. The following example procedures aid in increasing read consistency. In an example environment, the following initial-state assumptions regarding the setup and operation of the overall conveyor system are appropriate:  
      (a) ULDs are positioned in front of the appropriate reader, with the center of the ULD aligned to the center of the reader.  
      (b) ULDs do not have to be connected. However, they maintain a separation distance to avoid misreads into adjacent ULDs.  
      (c) Any reader not servicing a ULD should be turned off, or configured so that it is not feeding information to the BMS.  
      (d) Heavy bags should be handled by two workers for placement into a ULD (e.g., to avoid damage to tags, etc.).  
      When a tag is read on a conveyor, this is not necessarily an error condition or misread, as baggage handlers typically utilize the conveyor to move a bag as close as possible to the ULD prior to loading. Misreading of bags can occur when bags that are placed inside a ULD are visible to reading stations that are not supposed to be covering that particular ULD.  
      An important metric of a conveyor system is to support a 100% correct bag count and accurate manifest generation.  
      As described above, RFID coverage in front of a ULD is dynamic. Tag reads on the conveyor are difficult to entirely eliminate, and will vary depending on how full the ULD is loaded and where the baggage handler is standing.  
       FIG. 11  shows an example flowchart  1100 , providing baggage handling logic for a conveyor system, according to embodiments of the present invention. The steps of  FIG. 11  do not necessarily have to occur in the order shown, as will be apparent to persons skilled in the relevant art(s) based on the teachings herein. Furthermore, not all steps of flowchart  1100  are required in every application, and in some applications, additional or alternative steps occur. These alternative embodiments are also within the scope and spirit of the present invention. Other structural embodiments will be apparent to persons skilled in the relevant art(s) based on the following discussion. The steps of flowchart  1100  are described in detail below.  
      In step  1102 , a hand-held terminal (or other computing device) configures a conveyor. Operation proceeds to step  1104 .  
      In step  1104 , an OFU button is pressed to activate a reader. Operation proceeds to step  1106 .  
      In step  1106 , a bag arrives at the conveyor Baggage arriving at the conveyor system typically arrives via an automated transfer system, which delivers the bag via a metal chute to the head of one of two conveyors. Baggage can also be delivered from areas external to the conveyor, such as “hand carries” or carts of luggage from another conveyor system, or by other procedures. Operation proceeds to step  1108 .  
      In step  1108 , if the bags arrive via manual delivery, operation proceeds to step  1110 . Alternatively, if the bags arrive via conveyor, operation proceeds to step  1112 .  
      In step  1110 , the bags arriving via manual delivery are stopped outside of any readers active read area. Operation proceeds to step  1114 . Baggage arriving from an external area should be placed outside of the active read areas on the lateral conveyor line so that they are not seen/read by the tracking system until they are ready to be placed inside a ULD.  
      In step  1114 , if a single bag is being manually delivered, operation proceeds to step  1116 . Alternatively, if a cart containing a plurality of bags is being delivered, operation proceeds to step  1118 .  
      In step  1116 , the tag of the bag is examined, and the bag is transported to the appropriate ULD. Operation proceeds to step  1126 . For example, the tag may include text information, a bar code, or other information, that would indicate to an operator which ULD is appropriate for the corresponding bag. In an embodiment, a barcode tag on each bag coming from an external area can be examined to determine the appropriate ULD to which the bag is delivered.  
      For example,  FIG. 12  shows a bag  1202  being placed in a ULD  104  in an active read area  802   c  of a reader  806   c . As shown in  FIG. 12 , bag  1202  is transported in a manner to avoid entering active read areas  802   a  and  802   b , to prevent an inadvertent reading. Note that a bag can alternatively be taken in front of ULDs  104  to a desired ULD  104 , such as from an external bag staging area. However, such action may generate extra reads to the BMS from the readers that the bag passes.  
      Bags on a conveyor are selected as appropriate for placement into a ULD. Similar to external bag delivery, a barcode tag on a selected bag can be examined to determine the appropriate ULD it is to be placed in. If the conveyor is full of bags, a bag may be removed from anywhere on the line and carried directly to the appropriate ULD. Note that if the bag is transported to the destination ULD with the tag facing down (away from the readers) interim reads will be minimized. If the conveyor is empty, a baggage handler may use the conveyor to move the bag as close as possible to the appropriate ULD before placing it inside, such as shown in  FIG. 13  for a bag (shown as moving along a path indicated by an arrow  1304  in  FIG. 13 ).  
      In step  1118 , a bag is removed from the cart, and operation proceeds to step  1116  for the removed bag.  
      In step  1112 , if the tag of the bag is visible (e.g., on the top side of the bag), operation proceeds to step  1120  (when present). Alternatively, when the tag of the bag is not visible, operation proceeds to step  1122 . Bags arriving on the conveyor may be checked to see if the RFID tag on the bag is facing up. If it is, baggage handlers have the option of flipping, or otherwise repositioning the bag so that the tag is facing towards the belt. By doing this, extra reads to the BMS will be minimized as the bag travels down the conveyor belt.  
      In step  1120  (when present), the bag is repositioned to move the tag to the bottom side of the bag (e.g., the bag may be flipped over so that the tag is face down on the conveyor). Operation proceeds to step  1124 .  
      In step  1122 , the bag is not repositioned. Operation proceeds to step  1124 .  
      In step  1124 , the bag is selected from the conveyor. Operation proceeds to step  1116 .  
      In step  1126 , the bag is placed in the ULD. Operation proceeds to step  1128 . Regardless of how a bag arrives at a conveyor, when the bag is placed into the ULD, the baggage handlers should try to ensure that the RF tag on the bag is facing up and pointing towards the reader antenna prior to placement in the ULD. Doing this will maximize the read rate of the tags.  
      In step  1128 , if the OFU responds, operation proceeds to step  1130 . Alternatively, if the OFU does not respond, operation proceeds to step  1132 . For example, as the bag enters the capture zone, the tag will be read by the reader, and the OFU will respond with an indicator, such as a light, to indicate whether the bag can be loaded.  
      In step  1130 , if the OFU status is positive (e.g., bag is properly placed), operation proceeds to step  1132 . Alternatively, if the OFU status is negative (e.g., the bag is not properly placed), operation proceeds to step  1116 . For example, in an embodiment, the OFU responds to a bag read with either a red or a green light. The duration of this light response is user definable, and should be long enough for the baggage handler to easily notice, such as for 2 seconds. For example, if the OFU shows a solid green light and presents a short audible tone, the bag is at the correct ULD and should be placed inside. If the OFU shows a solid red light and a long audible tone, the bag is incorrect and should not be loaded into that ULD. In this case, the bag label is re-examined, and the bag is transported to the appropriate ULD.  
      In step  1132 , the bag is placed/allowed to remain in the ULD. Operation proceeds to step  1142 .  
      In step  1134 , the bag is repositioned to attempt to have the associated tag read. Operation proceeds to step  1136 .  
      In step  1136 , if the OFU responds, operation proceeds to step  1130 . Alternatively, if the OFU does not respond, operation proceeds to step  1138 .  
      In step  1138 , the bag is moved aside (e.g., placed back on the conveyor). Operation proceeds to step  1140 .  
      In step  1140 , the bag is processed using a hand-held (or other computing device). Operation proceeds to step  1142 .  
      In step  1142 , if the bag is the last bag to be processed, operation proceeds to step  1144 . Alternatively, if there are further bags to process, operation proceeds to step  1146 .  
      In step  1144 , the manifest is reconciled.  
      In step  1146 , a next bag is selected. Operation proceeds to step  1116  for the next bag.  
      If baggage handlers take a bag to a desired ULD, and thereby pass in front of other OFUs, the interim OFUs may read the tag and respond with a light sequence. This can be a normal part of the operation and any feedback from these OFUs can be ignored. However, care should be taken as bags are taken past intermediate ULDs and their associated read areas, to ensure they are not triggering OFU lights at the same time another bag is being loaded into that particular ULD. To avoid this problem, if a first person is loading a ULD, a second person can wait until the first person has actually loaded the bag before passing through the read area. In another example, a person can place their hand over a tag while in transit to the destination ULD to prevent the tag from being read at intermediate locations.  
      Example Operator Instructions  
       FIG. 15  shows an example flowchart  1500 , describing operation of a conveyor system, according to an example embodiments of the present invention. Other structural embodiments will be apparent to persons skilled in the relevant art(s) based on the following discussion. The steps of flowchart  1500  are described in detail below.  
      In step  1502 , a conveyor system is configured for a departing flight.  
      In step  1504 , reader stations are activated in front of each ULD.  
      In step  1506 , manifest data is captured.  
      In step  1508 , the reader station(s) in front of each ULD are closed.  
      Details relating to the steps of flowchart  1500  with respect to example embodiments are further described below.  
      Configuration of the Conveyor System  
      With regard to step  1502 , configuration of the conveyor system to track bags can be accomplished using a wireless-enabled hand held device, or other device. For example, a hand held device can be used to initially communicate with the BMS to associate/assign the flight to the conveyor, and then assign each conveyor as necessary to a ULD, along with the type of bags that it will contain.  
      Once the device has configured the conveyor system for use, each station can be activated to start the data collection process.  
      Activation of Reader Stations  
      With regard to step  1504 , each station contains an antenna and an OFU. In an embodiment, the OFU includes a set of three lights and a buzzer which are mounted on top of the antenna, and a momentary contact button which is mounted on a box directly below the antenna. Once the hand held device (or other device) has been used to configure the conveyor with the flight and ULD information, a reader station can be activated by pushing the button on the OFU. Once this is done, the antenna is activated, and any RFID tags seen by the reader station will signal an OFU response.  
      Capturing of Manifest Data  
      With regard to step  1506 , bags being processed on the conveyor should each have a valid RFID tag attached to it. The data on this tag is captured and used to generate the bag manifest for the flight. Manifest data is normally captured as bags are placed into the ULD, but can also be captured manually, such as in the case of a faulty or missing tag (such as in step  1140  of  FIG. 11 , described above).  
      Closing of Reader Station in front of each ULD  
      With regard to step  1508 , after the appropriate bags have been loaded into the ULD at a reader station, the ULD can be “closed” from a data collection perspective. Closing a reader station essentially means that the antenna and OFU are disabled, and will not record any more bag information. In an embodiment, to close a reader station at a conveyor, a button underneath the OFU of the desired reader station is pressed.  
      Bill of Materials for an Example Conveyor System  
       FIG. 14  shows a block diagram for a reader  1402 , according to an example embodiment of the present invention. For instance, reader  1402  is an example of a controller  1006  shown in  FIG. 10 . In the example of  FIG. 14 , reader  1402  includes a reader module  1404 , an I/O module  1406 , a serial board  1408 , an Ethernet switch  1410 , and a power unit  1412 .  
      Reader module  1404  includes one or more receiver and transmitter pair signal ports for communications with four corresponding antennas. Four receiver and transmitter pairs are shown in the example of  FIG. 14 . In an embodiment, for example, reader module  1404  can be a special purpose or commercially available reader, such as an AR-400 reader sold by Matrics, Inc., of Columbia, Md.  
      I/O module  1406  has one or more I/O signal ports for communicating with one or more OFUs. Three I/O signal ports are shown in the example of  FIG. 14 .  
      Serial board  1408  provides serial communication functionality and buffering for reader  1402 .  
      Ethernet switch  1410  is used to interface reader module  1404 , I/O module  1406 , and serial board  1408  of reader  1402 . Furthermore, Ethernet switch  1410  may be coupled to a BMS, to allow reader  1402  to communicate with the BMS.  
      Power unit  1412  receives an external input voltage, and converts the input voltage/power to an appropriate output voltage/power for powering the components of reader  1402 . For example, power unit  1412  may convert an input voltage of 220 V AC (alternating current) to an output voltage of 24 V DC (direct current). In an embodiment, all reader stations  1402  are connected to a dedicated and conditioned power circuit to avoid voltage fluctuations from large motors, etc., such as starting and stopping. In an example embodiment, a controller  1006  of  FIG. 10  includes reader module  1404 , I/O module  1406 , serial board  1408 , Ethernet switch  1410 , and power unit  1412 . In an example embodiment, reader module  1404  is an AR400 reader, distributed by Matrics, Inc. of Columbia, Md., or other reader type. In an example embodiment, I/O module  1406  is an I/O module distributed by Acromag of Wixom, Mich., or other I/O module type. In an example embodiment, serial board  1408  is a multiport serial board distributed by Moxa Technologies, Inc., of Brea, Calif., or other serial board type. In an example embodiment, architecture  1000  of  FIG. 10  can be incorporated into a Gantry system. For example, the Gantry system can be commercially available, or custom built to support six reader stations.  
      Fault Management  
      A lateral conveyor reader system can suffer from one or more problems, including those described in this subsection. For example, the system may suffer from excessive reads of tags on conveyor belts. Possible causes for this problem may include an antenna angle that is too sharp, a ULD that is mis-positioned, or one or more bags positioned too far forward on a conveyor belt. Thus, this problem may be corrected, as would be understood by persons skilled in the relevant art(s) from the teachings herein.  
      In another example, a system may suffer from difficult and/or slow tag reads. Possible causes for this problem may include a damaged tag, an operator standing between an OFU and a bag, a tag not oriented properly with respect to an antenna, or a ULD located too far from an antenna. Thus, this problem may be corrected, as would be understood by persons skilled in the relevant art(s) from the teachings herein.  
      In an embodiment, a system may suffer from a problem of not being able to read a bag. Possible causes for this problem may include a damaged tag, a bag already seen by a reader, a reader station that is not registered, or a reader station that is not activated. Thus, this problem may be corrected, as would be understood by persons skilled in the relevant art(s) from the teachings herein.  
      Operation Verification  
      Once a conveyor system has been installed and configured, a test procedure may be followed to ensure that an installed conveyor system is functioning correctly. The test procedure identifies and notes error conditions, which can then be corrected. A test procedure can be repeated until the system operates at 100%.  
      In order to perform the below described example functional test, ULDs and bags are not required, only the tags and information necessary to test the system are used.  
      Example Functional Test  
      A purpose of this example functional test is to verify the operational status of conveyor system components and software.  
      Items used for the example test include: (a) a RFID test tag set consisting of a set of six tags, each assigned to a respective unique ULD position at the conveyor; (b) a test flight manifest linking the RFID test tag set to the six corresponding ULDs; (c) barcode or similar information identifying the six test ULDs to the BMS system.  
       FIG. 16  shows a flowchart  1600 , providing an example functional test procedure for a conveyor system, according to embodiments of the present invention. The steps of  FIG. 16  do not necessarily have to occur in the order shown, as will be apparent to persons skilled in the relevant art(s) based on the teachings herein. Furthermore, not all steps of flowchart  1100  are required in every application, and in some applications, additional or alternative steps occur. These alternative embodiments are also within the scope and spirit of the present invention. Other structural embodiments will be apparent to persons skilled in the relevant art(s) based on the following discussion. The steps of flowchart  1600  are described in detail below.  
      In step  1602 , power to a reader unit is turned on. In an example embodiment, an operator verifies that a yellow light is on for each OFU.  
      In step  1604 , the ULDs are registered, and the OFU registration sequence is verified at each station. For example, a handheld device (or other computing device) can be used.  
      In step  1606 , each OFU is interacted with to register the respective reader. In an example embodiment, a button at each OFU is pushed to register the reader. The OFU is observed to verify that proper feedback is received.  
      In step  1608 , a RFID tag is presented to the reader that should provide a valid load indication. For example, a RFID tag that does match the conveyor position can be presented to test for the valid load indication. The OFU is observed to verify that proper feedback for a valid load is received.  
      In step  1610 , a RFID tag is presented to the reader that should provide an invalid load indication. For example, a RFID tag that does not match the conveyor position can be presented to test for the invalid load indication. The OFU is observed to verify that proper feedback for an invalid load is received.  
      In step  1612 , each OFU is interacted with to close the respective reader. In an example embodiment, a button at each OFU is pushed to close the reader. The OFU is observed to verify that proper feedback is received.  
     CONCLUSION  
      While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.