Abstract:
A system determines real-time locations of railcars in a railroad environment. Railcars are equipped with at least four RFID tags. A RFID reader at a fixed location at every track branch in the environment reads the RFID tags. Railcar locations are updated for the railcars by determining the branches on which the railcars are located.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates generally to tracking railcars, and more particularly to real-time computer systems for tracking railcars in a rail yards and train depots.  
       BACKGROUND OF THE INVENTION  
       [0002]     Rail yards and train depots perform important services such as freight distribution, railcar interchange and termination, and railcar inspection and maintenance. Therefore, management of railcars in the yards and depots is important for efficient railroad operation. Therefore, there is a need for a system that can provide real-time information on the location and status of railcars in the yards and depots.  
         [0003]     U.S. Pat. No. 6,637,703 describes a system for tracking railcars by using an automated equipment identification (AEI) reader, which is also called as radio frequency identification (RFID) reader, and elevated cameras. Railcars in a yard are tracked by recognizing patterns in video images acquired by the cameras, and signals acquired by the readers. In general, it is known that pattern recognition is less accurate and less reliable for moving objects under changing lighting conditions.  
         [0004]     U.S. Pat. No. 6,511,023 describes a system for tracking railcars by using AEI readers and wheel counting stations. A train traveling on a track is identified by the AEI readers. The wheel counting stations are located between the AEI readers to augment the identification locations. However, trains with the same number of wheels cannot be distinguished by that system. This is a particular problem in a rail yard or train depot where most trains are either relatively short, e.g., a single railcar, or the number of railcars in a train is changing dynamically.  
         [0005]     U.S. Pat. No. 6,377,877 describes a system for tracking railcars by comparing a location and an itinerary of a railcar. The location is acquired from a GPS system. Because the railcar is not identified specifically, incorrect information can be collected.  
         [0006]     U.S. Patent Application Publication 2005/0205719 describes a system for tracking a railcar equipped with an on-board communication system, including a location determining system and a transceiver for receiving and transmitting railcar data. The on-board system requires a power source and maintenance, increasing the cost of the system.  
         [0007]     It is desired to provide a railcar tracking system and method that can accurately and reliably locate railcars in real-time in rail yards and train depots.  
       SUMMARY OF THE INVENTION  
       [0008]     One embodiment of the present invention provides a railcar tracking system. Railcars are equipped with automated equipment identification (AEI) RFID tags. AEI readers are arranged in a railroad environment, e.g., a rail yard or train depot, particularly at entry and exit rail branches. An order in which the railcars are identified by the readers can be used to determine the location of trains.  
         [0009]     Another embodiment of the invention distinguishes between single rail cars, and multiple railcars coupled as a train. Each railcar is equipped with at least four AEI RFID tags. The RFID tags are attached approximate to the four corners of the car, e.g., on each side of the railcar near the ends so that AEI readers on either side of the track can read the tags. The alignment and range of the AEI reader can be adjusted so that the tags on the rear of one railcar and the front of a following railcar can be read concurrently only if the two railcars are coupled.  
         [0010]     Another embodiment of the invention provides a system and method for updating train information in real-time. Mobile AEI readers with computing and communication resources are used for synchronizing real operation and a database in a server. Users of the readers read the two RFID tags during coupling and uncoupling operations. The updated train information can be verified automatically when the train is passing a trackside AEI reader.  
         [0011]     Another embodiment of the invention provides a decision support method for yard and depot operation using dynamic railcar allocation and scheduling. The method uses the real-time coupling information to allocate a block of coupled railcars to a train and to reduce operational cost of the coupling and uncoupling operations.  
         [0012]     Another embodiment of the invention provides more accurate identification of railcars in a railroad environment where many AEI readers are close to each other because the tracks are spaced relatively close. The AEI readers are combined with optical components, such as infrared readers or cameras, and photo emitters. This way, a particular AEI reader can be activated by the optical components when the railcar is on a selected track. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a top view of railroad environment including a train, an AEI reader and RFID tags according to an embodiment of the invention;  
         [0014]      FIG. 2  is a top view of rail yard including a train, multiple AEI readers and RFID tags according to an embodiment of the invention;  
         [0015]      FIG. 3  is a side view of two railcars according to an embodiment of the invention;  
         [0016]      FIG. 4  is a top view of a railroad environment including trains on different tracks, an AEI reader, a sensor, and RFID tags according to an embodiment of the invention; and  
         [0017]      FIG. 5  is a block diagram of a railcar tracking system according to an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]      FIG. 1  shows a small portion  100  of a railroad environment, e.g., a rail yard or train depot. The environment includes an automated equipment identification (AEI) reader  5 , AEI RFID tags  11 - 14  attached to a railcar  1 , and AEI RFID tags  21 - 24  attached to a railcar  2 . Every RFID tag includes a unique identification (ID) that can be read by the AEI reader  5 . The RFID tags are placed near the corners of the railcars, e.g., on the sides and near the ends of the railcars. Multiple RFID tags are used to increase reliability of reading the RFID tags.  
         [0019]     The AEI reader  5  is located adjacent to a track  8 . The reader uses radio frequency (RF) signals  6 . A range and direction of the RF signals  6  is adjusted so that the reader  5  can only read one RFID tag at a time, unless two adjacent railcars are coupled by a coupler  7 . In this case, the reader  5  can concurrently read only two RFID tags on abutting comers of the two coupled railcars. When the railcars  1 - 2  move on the track in a particular direction  9 , the reader  5  reads the RFID tags in a corresponding order.  
         [0020]      FIG. 2  shows a larger portion  200  of the railroad environment. The environment includes readers  5  having RF ranges  6  adjacent to tracks. The readers are located at entry, exit, and branch points in the environment. A train  10  with cars A-D is located on track  8 . Additional readers can be located for special purposes. One example is an inspection depot  150  where railcars can be inspected and inspection information can be associated with railcar identifications.  
         [0021]      FIG. 3  shows coupled railcars  1 - 2  and tags  12 - 21  according to the invention. Some railcars have couplers  7  and a key  71 . The key  71  determines if the cars can be uncoupled. A mobile AEI reader  4  can be used to read and confirm the identification of the railcars involved in coupling/uncoupling operations. The identification can be exchanged with a database using a wireless connection.  
         [0022]     One example of the operation flow is described below. 
    1. A central operator requests the uncoupling of railcars  1 - 2  via a computer system.     2. Locomotive and coupling crews are notified of the request.     3. The RFID tags  12  and  21  are read by the system to confirm the railcar locations.     4. The key  71  is removed.     5. The system sends an instruction to the crews to move a locomotive for the uncoupling.     6. The key  71  is reinserted.     7. The system completes the operation and updates the status.     8. The central operator can check all the procedures in real-time in an operation room.    
 
         [0031]      FIG. 4  shows an AEI reader  5  in close proximity to tracks  8 - 9 . It is possible, due to the range  6  of the reader, that the reader can read RFID tag  32  on railcar  3  on track  9 . This can cause errors in the system. According to an embodiment of the invention, the reader  5  can be associated with a sensor  40  to detect the railcar  3  on the correct track. The read IDs can be valid only while the sensor is detecting the railcar, or the reader can stop interrogating the RFID tags until the sensor detects the railcar. Thus, the system can prevent reading RFID tags on the wrong track. The sensor also helps to detect failure of reading the RFID tags on the correct track. The stopping interrogation of the reader can also reduce interference between readers substantially colocated in the environment. Thus the sensor can improve reliability of the AEI system in the yard/depot.  
         [0032]     The sensor  40  can be an infrared-based distance sensor, or a camera and an image-processing unit.  
         [0033]      FIG. 5  is a block diagram of a railcar tracking system  500  according to an embodiment of the invention. A server  510  can be located in a central or distributed operation room. Components of the server  510  can include a communication interface  501 , a railcar location management system  502 , an operation system  503 , and a resource planning system  504 . These components can be implemented in a single computer or multiple computers, which are connected by a network  550  via the communication interface  501 . The network  550  can be implemented using conventional networking equipment, such as Ethernet and a wireless local area network (LAN).  
         [0034]     Readers  5  are interfaced to the server through connections  511 , which can be wired or wireless, and the network  510 . Sensors  40  can be connected to readers  5 , which usually have processors inside and can transmit additional information from the sensor as well as tag IDs to the server. Another embodiment can use integrated readers that embed the sensor so that the installation can be simpler. Mobile readers  4  are connected to the server via wireless connection  512 . The readers  4  also include a display to show tag IDs, and associated information and commands from the system, etc. The associated information can include a name, status, specification, instructions, location and image of the railcar so that the railcar can be identified.  
         [0035]     Terminals  520  are installed in locomotive cockpits and are connected to the server via wireless connection  513 . The terminals  520  can show commands and status sent from the system. Inspection machines  150  can be associated with collocated AEI readers  5 . The inspection machines are connected via wireless connections  514 . In another embodiment, the inspection machine can also have a direct communication to the server, and the result and tag ID are associated in the server. In another embodiment, the inspection machine and the AEI reader are integrated for easier installation. Client computers  530  can also be connected to the system to provide user interfaces. For example, an operator can see the current location and status of the railcars graphically using the railcar location management system, issue commands to the crew and the workers in the yard/depot using the operation system, and plan interactively the resource allocation using the resource planning system.  
         [0036]     When IDs are read by a particular AEI reader  5  from the RFID tags on the railcars, the tag information is sent to the server  510 . The communication interface  501  controls the data flow between AEI readers and application systems in the server. Pre-registered locations of the readers are added to the ID data and sent to the railcar location management system, which updates the location of identified railcars.  
         [0037]     When there are two IDs in a single read event, those IDs are associated with coupled railcars. The railcar location management system can also manage the inspection status sent from the inspection machine and the reader.  
         [0038]     The resource planning system  504  can use information in the location management system to allocate railcars optimally to trains, which are operated on by the operation system. The resource planning system can have an optimization method, which uses the coupling information in order to allocate a block of railcars to a train and to minimize a total cost including re-blocking cost. The optimization method can also consider the inspection status and schedule of each railcar as a constraint, so that a failed or not-yet-inspected railcar is not allocated to a train.  
         [0039]     Because the location management system updates in real-time, the resource planning system can make use of the real-time information and update the resource plan in real-time, and thus the system can reduce the operation cost of the yard/depot and recover the operation flexibly from any accidents or failure.  
         [0040]     Although the invention has been described by way of examples of preferred embodiments, it is to be understood that various other adaptations and modifications may be made within the spirit and scope of the invention. Therefore, it is the object of the appended claims to cover all such variations and modifications as come within the true spirit and scope of the invention.