Abstract:
System, method and program for sensing and controlling spacing between railroad trains. A first train broadcasts its identity and current time of day to an RFID mounted adjacent to a railroad track approximately when the first train reaches the RFID. In response, the RFID records the identity of the first train and the time of day approximately when the first train reached the RFID. The first train proceeds past the RFID. Subsequently, a second train on the railroad track reaches the RFID and reads from the RFID the identification of the first train and the time of day approximately when the first train reached the RFID. Based on a comparison to the time of day approximately when the first train reached the RFID as read from the RFID to a time of day approximately when the second train reached the RFID, a determination is made as to a time-spacing between the first and second trains. If the time-spacing is below a threshold, an operator of the second train may be alerted.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to electronics and methods for sensing and controlling spacing between railroad trains. 
       BACKGROUND OF THE INVENTION 
       [0002]    It is common for different railroad trains to utilize the same railroad tracks with spacing between the different railroad trains proceeding in the same direction, based on different schedules for each train. However, often times, trains are late and occasionally, trains are early. This alters the spacing between different trains proceeding in the same direction, as intended by the schedules, and poses some risk of rear-end collision, depending on the scheduled spacing between the trains and the amount of buffer built into the schedule. 
         [0003]    A TagMaster (tm of TagMaster.com) system tracks a location of a train as follows. A tag identifying the train is mounted directly on a locomotive or other railroad car, and a reader is mounted on the side of the track. When the train passes the reader, the reader records the identity of the train and the time that it passed. Thus, the TagMaster system provides information as to the location of the train. This information can be used to update passenger information displays at railroad stations and terminals. 
         [0004]    An SAIC RailNet Automatic Equipment Identifier System also tracks a location of a train as follows. An Automatic Equipment Identification (“AEI”) reader system identifies rail equipment by reading electronically coded RFID tags mounted to locomotives, railcars, trailers, end-of-train units and intermodal containers. The AEI reader system automatically tracks railcars via the RFID tags, and makes railcar location information available for asset management and other purposes. The RailNet Automatic Equipment Identifier System stores AEI tag data including time, date, train direction and speed. 
         [0005]    Active and Passive RFIDs are well known today. Typically, an Active and Passive RFID includes identification or other information about a device to which the RFID is attached. An Active RFID (as well as an RFID reader) has an internal power source, and the ability to broadcast on its own initiative. An Active RFID can broadcast sufficient RF energy to a Passive RFID nearby to power the Passive RFID. The Active RFID can also write data into the Passive RFID for subsequent broadcast by the Passive RFID. A Passive RFID broadcasts its information when the Passive RFID is powered either by an Active RFID or an RFID reader. It is common to attach Passive RFIDs to goods sold in stores as antitheft devices and/or to assist in check-out. It was also known to replace road signs with RFID tags attached to posts and fences, and embedded in road surfaces. A receiver/advice unit in an automobile&#39;s dash instrument panel informs the driver of traffic advisory warnings, speed limits, obstacles and other things. 
         [0006]    An object of the present invention is to sense and control spacing between railroad trains and delivering this information directly to the operator of the train. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention resides in a system, method and program for sensing and controlling spacing between railroad trains. A first train broadcasts its identity and current time of day to an RFID mounted adjacent to a railroad track approximately when the first train reaches the RFID. In response, the RFID records the identity of the first train and the time of day approximately when the first train reached the RFID. The first train proceeds past the RFID. Subsequently, a second train on the railroad track reaches the RFID and reads from the RFID the identification of the first train and the time of day approximately when the first train reached the RFID. Based on a comparison to the time of day approximately when the first train reached the RFID as read from the RFID to a time of day approximately when the second train reached the RFID, a determination is made as to a time-spacing between the first and second trains. If the time-spacing is below a threshold, an operator of the second train may be alerted. 
         [0008]    According to other features of the present invention, an RFID mounted in a caboose or other last car of the first train broadcasts the identity of the first train and a current time of day to the RFID mounted adjacent to the railroad track. An RFID mounted in a locomotive in the second train reads from the RFID mounted adjacent to the railroad track the identification of the first train and the time of day approximately when the first train reached the RFID. 
     
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0009]      FIG. 1  illustrates a system, including an Active RFID in a caboose of a railroad train, an RFID reader and a control program in locomotive of a railroad train and a Passive RFID in or near a railroad track, for sensing and controlling railroad train spacing according to the present invention. 
           [0010]      FIG. 2  is a flow chart of processing by the Active RFID and Passive RFID when a leading railroad train reaches the Passive RFID. 
           [0011]      FIG. 3  is a flow chart of processing by the RFID reader, control program and Passive RFID sometime later, when a trailing railroad train passes overhead of the Passive RFID. 
           [0012]      FIG. 4  is a schematic diagram of the Passive RFID in or near the railroad track of  FIG. 1 . 
           [0013]      FIG. 5  is a schematic diagram of the Active RFID in the caboose of the leading railroad train of  FIG. 1 . 
           [0014]      FIG. 6  is a schematic diagram of the RFID Reader in the locomotive of the trailing railroad train of  FIG. 1 . 
           [0015]      FIG. 7  is a block diagram of a control unit within the system of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    The present invention will now be described in detail with reference to the figures.  FIG. 1(   a ) illustrates a railroad train  16  with a known locomotive  19 , caboose  17  and other intermediary railroad cars  27  on a railroad track  14 .  FIG. 1(   b ) illustrates another, railroad train  116 , behind railroad train  16 , with a known locomotive  119 , caboose  117  (or other rear car) and other intermediary railroad cars  127  on railroad track  14 .  FIGS. 1(   a ) and  1 ( b ) also illustrate a distributed, train spacing control system according to the present invention. The train spacing control system includes an Active RFID  22  mounted in the caboose  17  (or other last car) of railroad train  16 , a Passive RFID  32   a  mounted adjacent to railroad track  14  such as attached to railroad ties or within a housing or fixture adjacent to the railroad track, an Active RFID reader  33  mounted in locomotive  19  of railroad train  16  and a train spacing control unit  20  mounted in locomotive  19 . 
         [0017]      FIG. 7  further illustrates control unit  20  in locomotive  19 . Control unit  20  includes a known CPU  24 , operating system  25 , RAM  26  and ROM  27  on a bus  28 , and storage  29 . Control unit  20  also includes a train spacing control program  30  according to the present invention. A control unit  120  with a control program  130  in locomotive  119  is similar to control unit  20  and control program  30 . 
         [0018]      FIG. 2  is a flow chart of processing by Active RFID  22  and Passive RFID  32   a  within the train spacing control system when caboose  17  passes overhead of Passive RFID  32   a . Approximately at that time, Active RFID  22  in caboose  17  broadcasts authentication information (such as an identification of train  16  and a password or other shared secret) for train  16 , an identification of train  16  as well as a current time (from a clock  61  or GPS aboard caboose  17 ) (step  100 ). Passive RFID  32   a  receives the broadcast from Active RFID  22  and determines if train  16  is authentic and authorized to broadcast to Passive RFID  32   a  information regarding train  16  (step  104 ). An administrator previously entered authentication and authorization information into Passive RFID  32   a  for train  16 , and Passive RFID  32   a  stored this information in a table  93  in memory. If train  16  is not authentic or authorized (decision  106 , no branch), then Passive RFID  32   a  disregards the rest of the broadcast from Active RFID  22  (or whatever fraudulent device broadcast to Passive RFID  32   a ) (step  108 ). However, if train  16  is authentic and authorized (decision  106 , yes branch), Passive RFID  32   a  stores the identification of railroad train  16  and the current time of day (step  110 ). 
         [0019]      FIG. 3  is a flow chart of processing by control program  130  in control unit  120 , RFID Reader  133  and Passive RFID  32   a  sometime later, when locomotive  119  passes overhead of Passive RFID  32   a  (and presumably train  16  has further advanced along track  14 ). When locomotive  119  of railroad train  116  passes over Passive RFID  32   a , Active RFID reader/writer  133  broadcasts RF power to Passive RFID  32   a  as well as authentication information (such as an identification of train  116  and a password or other shared secret) for train  116  (step  120 ). Passive RFID  32   a  receives the broadcast from RFID Reader  133  (i.e. RFID  32   a  becomes activated) and determines if train  116  is authentic and authorized to receive information from Passive RFID  32   a  regarding train  16  (step  124 ). An administrator previously entered authentication and authorization information into Passive RFID  32   a  for train  116 , and Passive RFID  32   a  stored this information in table  93 . If train  116  is not authentic or authorized (decision  126 , no branch), then Passive RFID  32   a  disregards RFID Reader  133  and does not broadcast the information regarding train  16 , i.e. the identity of train  16  or the time of day it passed over Passive RFID  32   a  (step  127 ). However, if train  116  is authentic and authorized (decision  126 , yes branch), Passive RFID  32   a  broadcasts the information it has stored regarding railroad train  16 , i.e. passive RFID  32   a  broadcasts the identification of railroad train  16  and the time of day that caboose  17  of train  16  passed over Passive RFID  32   a  (and optionally, the geographic location of Passive RFID  32   a ) (step  130 ). RFID Reader  133  receives the information regarding train  16  and forwards this information to control program  130  (step  131 ). In response, control program  130  notes the current time of day (obtained from a clock  195  aboard locomotive  119  (step  132 ), and compares the current time of day to the time broadcast by Passive RFID  32   a  (i.e. the time that caboose  17  passed over Passive RFID  32   a ) to determine how much time has lapsed since caboose  17  passed over Passive RFID  32   a , i.e. the time spacing between caboose  17  of train  16  and locomotive  119  of train  116  (step  134 ). Control program  130  includes in a file  45  an amount of time that should have lapsed since caboose  17  of train  16  passed over Passive RFID  32   a , if both trains were on schedule. Control program  130  also includes in file  45  a minimum amount of time that should have lapsed since caboose  17  of train  16  passed over Passive RFID  32   a , to assure a safe distance between the end of train  16  and the beginning of train  116  at normal speeds. An administrator previously entered the foregoing information into file  45 . If the time lapse is less than a minimum threshold for either the scheduled time-spacing or minimum safe time-spacing (decision  136 , no branch), then program  130  notifies a conductor of train  116  to slow down (step  138 ) and if possible, contact an operator of train  16  or a central station to determine the problem and take corrective action, such as increasing the speed of train  16  or shorten subsequent stops by train  16  to increase the spacing from train  116 . If the time-spacing is greater than a minimum threshold for both the scheduled time-spacing or minimum safe time-spacing (decision  136 , yes branch), then program  130  records that all is well, and the current time and date (and optionally, the location of Passive RFID  32   a ) (step  140 ). 
         [0020]    There are various ways that control program  130  can determine the geographic location of Passive RFID  32   a , and therefore the location where the time-spacing measurement is made. In one embodiment, an administrator previously programmed into Passive RFID  32   a  the geographic location of Passive RFID  32   a  (based on a portable GPS unit deployed during installation of the Passive RFID  32   a ). In this embodiment, Passive RFID  32   a  broadcasts to RFID Reader  133  the geographic location of Passive RFID  32   a  in step  130  so that program  130  knows where the train  116  is located when the information is received from Passive RFID  32   a  regarding train  16 . In a second embodiment, control unit  120  includes a GPS device  195  which supplies current location information to control program  130  so that program  130  knows where the train  116  is located when the information is received from Passive RFID  32   a  regarding train  16 . In a third embodiment, when the conductor receives the notification from control unit  120  in step  138  that the time-spacing is too short, conductor can determine the location of train  116  from visual aids along the railroad track  14  or other knowledge of the train&#39;s location, such as which station is next. 
         [0021]      FIG. 4  illustrates Active RFID  22  in more detail. Active RFID  22  comprises a battery  39  (or other inherent power source), CPU  48 , random access memory  40  to store the authentication information and identification of train  17 , an RF encoding program  50  to supply in a secure manner the authentication information for train  16  and current time of day (and date) to Passive RFID  32   a , and a transceiver  42  and antenna  44  to broadcast the authentication information of train  16  and current time of day to Passive RFID  32   a . An administrator previously broadcast the authentication information for train  16  and identification of train  16  to Active RFID  22  via antenna  44  and transceiver  42  for storage in memory  40 . A clock  61  aboard caboose  17  continuously provides a clock signal  49  indicative of the current time of day (and date) to Active RFID  22 . 
         [0022]      FIG. 5  illustrates Passive RFID  32   a  in more detail. Passive RFID  32   a  comprises an antenna  64  and transceiver  62  to receive broadcast from Active RFID  22  to power Passive RFID  32   a  (by storage of energy in a capacitor  67 ) and receive the authentication information and identification of train  16  and the current time of day from Active RFID  22 . Passive RFID  32   a  stores the authentication information and identification of train  16  received from Active RFID  22  in memory  69  for comparison to the preprogrammed authentication and authorization information in table  91 . Passive RFID  32   a  also includes an RF authentication program  70  to determine whether Active RFID  22  is authentic and authorized to receive the identification of train  16  and current time of day from Active RFID  22 . Passive RFID  32   a  also stores authentication information for train  116 , subsequently receives the authentication information for train  116  from Active RFID  133 , and determines if train  116  is authentic and authorized to receive the identity of train  16  and time of day information from train  16 . 
         [0023]      FIG. 6  illustrates Active RFID Reader  133  in more detail. RFID Reader  133  comprises a battery  239  (or other inherent power source), CPU  248 , random access memory  240  to store the authentication information and identification of train  116 , an RF encoding program  250  to supply the authentication information for train  116  and identification of train  116  to Passive RFID  32   a , and a transceiver  242  and antenna  244  to broadcast the authentication information of train  116  and identification of train  116  to Passive RFID  32   a . An administrator previously broadcast the authentication information of train  116  and identification of train  116  to RFID  32   a  via antenna  244  and transceiver  242  for storage in memory  240 . A clock  195  aboard locomotive  119  continuously provides a clock signal  249  indicative of the current time of day (and date) to RFID Reader  133 . After authentication of train  116  to Passive RFID  32   a , Passive RFID  32   a  broadcasts its stored information regarding train  16 , i.e. the identification of train  16  and time of day (and date) that caboose  17  passed overhead Passive RFID  32   a . In response, RFID Reader  133  receives and stores this information regarding train  16 , and supplies this information to control program  130  in control unit  120  for processing as noted above. 
         [0024]      FIG. 1  also illustrates that railroad track  14  includes multiple other Passive RFIDs  32   b,c,d , etc. spaced along track  14 . The other Passive RFIDs  32   b,c,d  etc. are identical to Passive RFID  32   a ; the only difference is their respective locations along railroad track  14 . Consequently, as caboose  17  passes over each of the Passive RFIDs  32   a,b,c,d  etc., Active RFID  22  authenticates itself to each Passive RFID  32   a,b,c,d  etc. and writes the identification of train  16  and the then current time of day into each Passive RFID  32   a,b,c,d , etc. to indicate the successive times that caboose  17  passed over the respective Passive RFIDs. As locomotive  119  subsequently passes over each of the Passive RFIDs  32   a,b,c,d  etc. and the RFID Reader  133  powers the Passive RFIDs and authenticates itself to each of the Passive RFIDs  32   a,b,c,d  etc., the Passive RFIDs  32   a,b,c,d , etc. broadcast the identification of train  16  and the times that caboose  17  passed over the respective Passive RFIDs  32   a,b,c,d , etc. Consequently, RFID reader  133  in locomotive  12  will detect the times that caboose  17  passed over each of the Passive RFIDs  32   a,b,c,d , etc. Control program  130  includes in file  45  the locations of Passive RFIDs  32   a,b,c,d , etc. or receives from each Passive RFID  32   a,b,c,d  etc. its geographic location, and therefore can compute the average speed of train  16  between successive Passive RFIDs (based on distance between successive Passive RFIDs divided by time lapse between successive RFIDs) and the time spacing between trains  16  and  116  at each Passive RFID  32   a,b,c,d . (An administrator previously entered the foregoing location information into file  45 .) Control program  130  will also use the average speed to determine if train  116  is gaining on or falling behind train  16 , and therefore whether either train should adjust its speed to obtain or maintain a safe time-spacing, and the minimum safe distance for the current speeds of both trains. Passive RFIDs  32   a,b,c,d , etc. can be spaced along the entire railroad track  14 , or selective portions of railroad track  14  such as high congestion areas or inside tunnels where radio communication is limited or not available. 
         [0025]    Although not shown, caboose  117  in railroad train  116  also includes an Active RFID  122  similar to Active RFID  22 , and a locomotive of a railroad train (not shown) behind railroad train  116  includes an RFID reader similar to RFID reader  133  and a train spacing control unit similar to control unit  120 , so that the railroad train (not shown) behind railroad train  116  can determine a time-spacing between it and railroad train  116 . Likewise, locomotive  19  in railroad train  16  also includes an RFID Reader  33  similar to RFID Reader  133  and a train spacing control unit  20  similar to control unit  120 , and a caboose of a railroad train (not shown) ahead of railroad train  16  includes an Active RFID similar to Active RFID  22 , so that railroad train  16  can determine a time-spacing between it and the railroad train (not shown) ahead of railroad train  16 . 
         [0026]    Based on the foregoing, a system and method for sensing and controlling spacing between railroad trains have been disclosed. However, numerous modifications and substitutions can be made without deviating from the scope of the present invention. For example, the control unit may collect “trending” information of the previous train relative to information available locally in order to maintain proper train separation by sensing acceleration and deceleration of the preceding train requiring only accurate clocks on the trains, allowing this system to work within tunnels. 
         [0027]    Therefore, the present invention has been disclosed by way of illustration and not limitation, and reference to the following claims should be made to determine the scope of the present invention.