The invention relates generally to railroad end of train units, and more particularly to an improved method for keeping track of end of train units.
Within the railroad industry, end of train (EOT) units (sometimes also referred to as end of train devices, or ETDs) are typically attached at the rear of the last car on a train. These devices were originally designed to perform some of the functions previously performed by train personnel located in the caboose. Today, EOT units can perform a variety of functions. EOT units monitor air pressure in the air brake pipe and transmit this information to the head of the train (HOT). EOT units also often include an end-of-train marker light. Two-way EOT units can accept a command from the HOT to open the air brake pipe (loss of air pressure in the air brake pipe causes the brakes to activate and stop the train) in an emergency situation. Some EOT units include motion detectors that are used to inform the HOT as to whether, and in some cases in which direction, a train is moving. Other EOT units include GPS receivers that are used to transmit location information pertaining to the end of the train to HOT equipment as discussed in U.S. Pat. No. 6,081,769. EOT units usually communicate with the HOT using radio-based communications.
Supplying power to EOT units is an important consideration. As discussed in U.S. Pat. Nos. 5,267,473 and 6,236,185, it is known to supply power to EOT units using batteries or a combination of batteries and air-powered generators connected to the brake pipe. In order to conserve battery power, EOT units are usually configured to power down when the unit has been in a horizontal orientation for a period of time, such as after being removed from a train by train yard personnel.
Keeping track of EOT units has been a historical problem in the railroad industry. EOT units are expensive and can cost several thousand dollars for a single EOT unit. Because an EOT unit is necessary for each train, railroads are required to buy many EOT units. In addition to being expensive, EOT units are mobile since they are attached to the ends of trains. Unfortunately, this mobility can result in EOT units becoming misplaced. For example, it is often necessary to install and remove EOT units from individual cars in a train yard as consists are reformed. Because the EOT units are often heavy and bulky, yard personnel often simply lay the EOT units by the wayside for collection at a later time. EOT units left by the wayside in this manner often become misplaced or “lost.” Many EOT units are lost this way each year. Even a temporarily misplaced EOT unit can cost a railroad money. For example, rent must be paid for the time when an EOT unit from one railroad is in another railroad's territory. Thus, if another railroad's EOT unit is temporarily misplaced in a railroad's territory, the rent owed to the other railroad is increased as a result.
One solution to this problem is the subject of commonly-owned, co-pending U.S. patent application Ser. No. 10/611,279, filed Apr. 30, 2003, the contents of which are hereby incorporated by reference herein. However, further improvements to the inventions disclosed in that application are possible. What is needed is an apparatus and method for locating EOT units.
The foregoing needs are met to a great extent by a method and apparatus in which an EOT unit periodically reports its position to an EOT unit tracking station using wireless communication. In some embodiments, the EOT unit includes a cellular modem and periodically transmits a location message using a cellular network. In another aspect, the EOT units are equipped with transceivers and have the ability to receive a query message (i.e., a “ping”) and transmit a location message in response.
In some embodiments, the EOT units are configured to periodically reawaken from a low power state (which may be entered when the EOT units are laid on their sides along a wayside or elsewhere) in order to transmit the location message. After transmitting the location message, the EOT unit will revert to the low power state in order to conserve battery power. Some embodiments may also periodically awaken in order to determine whether any query messages have been directed toward the EOT units. This may be done at a more frequent rate than the transmission of the periodic location message. If no query message is received, the EOT unit reverts to the low power state without sending any message. In other embodiments, the EOT units have the ability to accept a “disable” message and enter a “no service” state until a special message is received. This is done to force the return of the EOT unit to the manufacturer, a repair facility, or some other location, for reactivation in order to provide an added degree of control over the EOT units.
In another aspect, an EOT tracking station is configured to receive the messages from the EOT units and display a location of the EOT units to a user such as an employee of the owner of the EOT units. The EOT location may be displayed textually (e.g., in latitude and longitude coordinates), but is preferably displayed graphically over a map. In highly preferred embodiments, the map display is made available over an interactive website in which users may select individual EOT units for positional display on the map or may select a specific region in which the locations of all EOT units present in the region are displayed. In some embodiments, the user of the website is given the option of initiating a query message and/or a disable message directed toward a particular EOT unit from the website.
A more complete appreciation of the invention and many of the attendant features and advantages thereof will be readily obtained as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
a and 1b are perspective and front views, respectively, of an EOT unit according to one embodiment of the invention.
The present invention will be discussed with reference to preferred embodiments of end of train units. Specific details, such as types of positioning systems and power supply subsystems, are set forth in order to provide a thorough understanding of the present invention. The preferred embodiments discussed herein should not be understood to limit the invention. Furthermore, for ease of understanding, certain method steps are delineated as separate steps; however, these steps should not be construed as necessarily distinct nor order dependent in their performance.
a and b illustrate an embodiment of EOT unit 100. The EOT unit 100 includes a housing 110 in which the internal components of the EOT unit 100 (discussed in further detail below) are located. A handle 111 is attached to the housing 110 to facilitate the installation and removal of the EOT unit 100 from a train car. Also attached to the housing is a connector 120 for connecting the EOT unit 100 to an air brake hose 10 which is in fluid communication with the train's air brake pipe (not shown in
A functional block diagram 200 of the EOT unit 100 of
The processor 210 is connected to control an EOT marker light 140 (although a direct connection is illustrated in
Also connected to the processor 210 is an air pressure transducer 240, which is in fluid communication with the air brake pipe 10 and configured to monitor the pressure in the air brake pipe 10. The processor 210 reads the pressure in the air brake pipe 10 and periodically transmits this information to the HOT using the HOT transceiver 250.
An emergency solenoid 280 is also connected to the processor 210 and the air brake pipe 10. When the processor 210 receives an emergency braking command from the HOT via the HOT transceiver 250, the processor 210 controls the solenoid 280 to open, causing a loss of pressure in the air brake pipe 10 and activation of the train's brakes. In some embodiments, another solenoid (not shown in
The processor 210 is further connected to a positioning system 270, which is a GPS receiver in preferred embodiments but may also be an INS (intertial navigation system), LORAN device, or any other positioning system. The positioning system 270 supplies the processor 210 with reports on the position of the EOT unit 100.
The processor 210 is also connected to a cellular modem 260. The processor 210 uses the cellular modem to send reports including an identifier of the EOT unit 100 and location (and preferably time) information obtained from the positioning system 270 to an EOT tracking station at periodic intervals. The processor 210 also receives “page” messages (messages requesting the EOT unit to report its current location) and “disable” messages (messages instructing the EOT unit to enter an non-operational state) via the cellular modem 260.
During normal operation, the processor 210 controls the EOT marker light 140, communicates air brake pipe pressure information to the HOT, activates the emergency solenoid 280 in response to commands from the HOT, and, in some embodiments performs other functions such as monitoring the status of a motion sensor and transmitting this information to the HOT. These normal operations will not be discussed further herein.
In addition to the normal operations discussed above, the processor 210 periodically transmits location messages. In preferred embodiments, the processor 210 transmits these messages even after the EOT unit has gone into a low power state. As discussed above, the low power state is entered into when the tilt sensor 230 indicates that the EOT unit 100 is in a horizontal position and/or the pressure in the air brake pipe has been lost for some threshold period of time, both of which are indications that the train is not in operation and the EOT unit 100 is not needed. In the low power state, no power is supplied to any component other than a counter circuit (not shown in
Both during normal operations and upon reawakening from the low power state as discussed above, the processor 210 periodically enters a “CALL” subroutine illustrated in
The EOT unit may also be programmed to respond to a query message (sometimes referred to as a “page”) in some embodiments. In some embodiments, the EOT units are programmed to respond to pages at all times. In other embodiments, the EOT units only check for pages during certain predetermined time periods (e.g., the ten minutes surrounding the top of each hour). Some embodiments will check for pages even while in the low power state while others will only check for pages when in the normal operational state. A flowchart of the “Answer Page” subroutine periodically performed by the processor 210 is illustrated in
As discussed above, some embodiments of the EOT unit 100 are also responsive to a disable message. The processing for such a message is similar to the processing of
Those of skill in the art will recognize that various modifications to the EOT unit 100 are possible. For example, it is possible to operate the EOT unit 100 solely with battery power rather than using batteries in conjunction with an air powered generator. Cellular modem 260 may be replaced with any type of wireless communication system. Various other modifications to the components of the EOT unit 100 are also possible.
The EOT unit 100 may communicate with any of a number of tracking stations via any of a number of methods. In preferred embodiments of the invention, the EOT unit 100 communicates with a centralized EOT tracking station that maintains a database of information pertaining to the EOT units and that is accessible to users via the Internet. There may be separate EOT tracking stations for individual railroads, or there may be a centralized EOT tracking station that monitors all EOT units. Such a centralized tracking station may restrict the EOT information that various users are able to view. In some embodiments, a user from a particular organization (e.g., a railroad) may only be allowed to view information pertaining to EOT units owned by that organization. In other embodiments, a user from an organization may be allowed to view information pertaining to EOT units that they own and EOT units owned by others that are within territory in which they own the tracks. The latter ability allows a railroad to quickly locate and return EOT units in their territory for which they are paying rent.
The Results window 440 displays the EOT identifier along with a last contact date and time (i.e., the date and time when the EOT device last reported its position). The Results window 440 also includes a Ping checkbox 441 and a History checkbox 442. When the Ping checkbox 441 is selected and the Ping button 436 is pressed by the user, a ping (query) message will be sent to the corresponding EOT unit (in embodiments in which the EOT units only respond to pages during certain time periods, the ping message will be delayed until the next period). Similarly, when the History checkbox is selected and the History button is pressed, a history of dates and times of prior location messages from the corresponding EOT unit will be displayed.
In addition to searching by EOT numbers, it is also possible to perform an area search using the “Near City/State” window 424. As shown in
The user may also focus on a particular EOT unit using the zoom icon 405. For example, unlike most of the EOT units shown in the map 403, EOT unit 77990 appears to be located away from any railroad tracks. After clicking on the zoom icon 405, the user may draw a box around EOT unit 77990. This will result in the display of a map 403 on a smaller scan with EOT unit 77990 at the center as shown in
In addition to the functions described above, the website also provides a Search All button 430 that, when pressed, will result in the display of all EOT units. A download button 438 will download textual information from selected EOT units to a file specified by the user. When the user presses the History button 436, an EOT History window 810 appears. The user can then enter the particular EOT units for which a history is desired in the EOT textbox 820 and a period of time for which the history is desired in the Age textbox 830. When the History button 840 is pressed, a map 910 showing the locations, dates and times of all messages received from the desired EOT units is displayed to the user as shown in
While the invention has been described with respect to certain specific embodiments, it will be appreciated that many modifications and changes may be made by those skilled in the art without departing from the spirit of the invention. It is intended therefore, by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the invention.