A METHOD AND AN ARRANGEMENT FOR MONITORING AND DETERMINING THE COMPLETENESS OF A TRAIN

Abstract

 An arrangement for monitoring and determining the completeness of a train moving along a railway track (3) has a first accelerometer (4) on board a front unit (5) of the train to measure accelerations of this unit. A second accelerometer (6) is arranged on board the last train unit (7) to measure accelerations of this unit. A transmitter (8) is associated with one of the accelerometers to transmit acceleration data measured thereby to a site of collection of such data from both accelerometers (4, 6). A device (11) compares these data and determines that the train is complete if the comparison shows that these data are the same and that at least the last train unit (7) is lost when said data differ.

Description

TECHNICAL FIELD OF THE INVENTION AND BACKGROUND ART

[0001] The present invention relates to a method for monitoring and determining the completeness of a train of a plurality of interconnected units moving along a railway track as well as an arrangement for obtaining this.

[0002] Trains of any conceivable type, such as passenger trains and freight trains mentioned as examples, are considered and the railway track may be a part of a railway of any type, anywhere, for example on main lines and in mining application.

[0003] It is in all railway systems important to keep track of all trains to avoid collisions. It is then not enough to keep track of the locos, because a train can lose one or more cars during the course of a journey. The traditional solution is to divide the track into sections and install track circuits on the ground, one track circuit per section of track. However, such track circuits are expensive, need a lot of maintenance, can be tricky to install, and failures can be very hard to correct.

[0004] Another possibility is to count the wheel axles every time a train enters a section of the track, and the number of axles should always stay the same during the journey. However, also axle counters are expensive. A further possibility is to let the train keep track of its position on the track and monitor its own integrity. This is what the present invention is occupied with. A train can be designed to report its integrity such that a section of the track occupied by the train is only made available to other trains after the train with confirmed train integrity has cleared that section. It is known to install navigation system devices using satellite positioning or inertial navigation on the loco (front train unit) and the last car (last train unit). The geographic location of these two devices should never be further apart than the length of the train. Also, the speed should not differ by more than a certain amount. However, this solution has limitations, such as the availability of satellites, particularly in tunnels.

[0005] Methods and arrangements for monitoring train integrity are disclosed in RU 2591551, DE 19828906, DE 10009324, and DE 10112920. All these methods and arrangements have disadvantages adhered thereto.

SUMMARY OF THE INVENTION

[0006] It is an object of the present invention to suggest an above method and arrangement being improved in at least some aspect with respect to such methods and arrangements already known.

[0007] This object is with respect to the method obtained by providing a method according to appended claim 1. Thus, train unit accelerations are measured by a first accelerometer on board a train unit being at the front of the train and by a second accelerometer on board a train unit being the last as seen in the moving direction of the train, these acceleration data are compared and it is determined that the train is complete if the comparison of acceleration data shows that said data are the same and that at least the last train unit is lost when said data differ. Thus, the method according to the invention is related to a known speed-and-position-based method. But instead of comparing geographic location and/or speed, the acceleration data is compared, i.e. checked for sufficient correlation. A train is not a rigid body, but investigations show that trains are sufficiently rigid to be treated as such. This means that the front of the train has very similar longitudinal acceleration, longitudinal velocity and has travelled the same distance as the back of the train at all times. If the front of the train undergoes the same longitudinal acceleration as the back of the train, then this means that the train integrity is intact. If one or more cars are lost, the acceleration data will start to differ. An advantage of using accelerometers for monitoring and determining the completeness of a train is that they dissipate less power than navigation systems. Another big advantage is a reduction of system complexity. Collection and sending of accelerometer data is much simpler than implementing an inertial navigation system which must keep track of train orientation, integrate measured accelerations continuously to determine speed and periodically correct for drift in the inertial navigation solution. This is important since it is tricky to provide electrical power at the end of for instance a freight train. Furthermore, accelerometers are not dependent on satellites and work fine in tunnels. Another advantage is that accelerometers are much cheaper than inertial measurement units, since high precision gyroscopes are not needed. Furthermore, by comparing acceleration data directly the issue of accumulated errors or "drift", typically of an inertial navigation system, is mitigated. The method is preferably carried out continuously as long as the train is moving for detecting a loss of integrity as soon as it appears, so that then an alarm can be radioed to an interlocking computer that stops all other traffic from coming near and possibly also derailers may be activated. However, it would be possible to intermittently carry out said method when this is done with a frequency being high enough.

[0008] "That said data are the same" does of course not mean that the data has to be identical to the last decimal, but data having a mutual certain deviation are of course to be interpreted as the same for avoiding false determination of an occurrence of a train unit loss, since a substantial data deviation will be detected as soon as a train unit is lost, and this will then be determined to be the case. It can be noted that the design is fail safe. Should one accelerometer fail so that it reports an incorrect value (or none at all), then the train integrity will be judged to be lost and restrictive action will be taken by the interlocking computer.

[0009] According to an embodiment of the invention the acceleration of the last train unit is in step a) measured by two said second accelerometers on board the last train unit, in step b) acceleration data obtained by both said second accelerometers are compared with acceleration data obtained by the first accelerometer, and it is in step c) determined that the train is complete if the comparison shows that acceleration data from one of the second accelerometers are the same as those from the first accelerometer. These types of sensors are cheap and dissipate low power, which makes it possible to provide this type of redundancy. It would of course also be possible to have two first accelerometers for having a redundancy also of the acceleration measurement in the front train unit or only have two first accelerometers and one second accelerometer.

[0010] According to another embodiment of the invention also the acceleration of the second last train unit is measured in step a) by a third accelerometer and in step c) these acceleration data are compared with the acceleration data obtained by the first accelerometer, and it is in step c) determined that when the acceleration data obtained by the third accelerometer differ from the acceleration data obtained by the first accelerometer at least two train units are lost. Such information could under some circumstances be interesting to obtain. It is of course possible to have accelerometers on more than two, such as on all, train units for knowing if more than two train units have been lost.

[0011] According to another embodiment of the invention an alarm is emitted if it is in step c) determined that at least the last train unit is lost. This enables an interlocking computer to stop all other traffic from coming near when deemed to be appropriate.

[0012] The object of the invention is with respect to the arrangement obtained by providing an arrangement with:

• a first accelerometer configured to be arranged on board a front unit of a train as seen in the intended moving direction of the train and to measure accelerations of the front train unit,
• a second accelerometer configured to be arranged on board a last train unit as seen in the intended moving direction of the train and to measure accelerations of the last train unit,
• at least one transmitter associated with one of said accelerometers to transmit acceleration data measured thereby to a site of collection of acceleration data from both accelerometers, and
• a device configured to compare acceleration data collected from the first accelerometer with acceleration data collected from the second accelerometer and to determine that the train is complete if the comparison shows that said data are the same and that at least the last train unit is lost when said data differ.

[0013] The advantages of such an arrangement appear clearly from the above discussion of the method according to the invention.

[0014] According to an embodiment of the invention said device is associated with one of said accelerometers, and said transmitter is configured to send acceleration data from the other accelerometer through a radio link to said unit for said comparison. It is suitable to have said device associated with one of the accelerometers, and it is then also possible to have each accelerometer provided with a said transmitter for bidirectional radio link communication between the accelerometer on the front train unit and the one on the last train unit.

[0015] According to another embodiment of the invention said device is configured to be arranged on board said front train unit in connection with said first accelerometer and the transmitter is associated with the second accelerometer. It may be suitable to have the device for comparing and determining on board the front train unit, i.e. the loco.

[0016] According to another embodiment of the invention at least one of the first and second accelerometers is included in a portable member being moveable from one train unit to another, and it is then advantageous to have the second accelerometer and the transmitter associated therewith included in a said portable member, since the train unit or car being the last unit in a train may change frequently while the front train unit is the same, so that it would at least from the cost point of view be advantageous to be able to move the second accelerometer with transmitter from one car to another when such changes occur.

[0017] According to another embodiment of the invention the arrangement comprises two said second accelerometers configured to be arranged on board a last train unit and to measure accelerations of this train unit, and said device is configured to compare acceleration data obtained by both said second accelerometers with acceleration data obtained by said first accelerometer and to determine that the train is complete if the comparison shows that acceleration data from one of the second accelerometers are the same as those from the first accelerometer.

[0018] Further advantages as well as advantageous features of the invention will appear from the description following below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] With reference to the appended drawings, below follows a specific description of embodiments of the invention cited as examples.

[0020] In the drawings:

Fig. 1

is a schematic view illustrating a train provided with an arrangement according to a first embodiment of the invention,

Fig. 2

is a schematic view illustrating the steps of a method according to an embodiment of the invention, and

Fig. 3

is a schematic view of a train provided with an arrangement according to a second embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0021] Fig. 1 illustrates schematically a train 1 of a plurality of interconnected units 2 (cars) moving along a railway track 3. This train is provided with an arrangement according to a first embodiment of the invention for monitoring and determining the completeness of the train, i.e. that the train has not lost any train unit. This arrangement comprises a first accelerometer 4 arranged on board the front unit 5, i.e. the loco, of the train as seen in the intended moving direction (arrow A) of the train and to measure accelerations of this front train unit 5. A second accelerometer 6 is arranged on board the last train unit 7 as seen in the intended moving direction of the train, and this second accelerometer is configured to measure accelerations of this last train unit. The second accelerometer is together with a transmitter 8 included in a portable member 9 being moveable from one train unit to another, so that this portable member may be applied on the last train unit on different trains, and if for instance the last three cars of the train shown in Fig. 1 would be deliberately disconnected and left in a railroad yard, this portable member 9 may be applied on the train unit 10 then being the last one. The transmitter 8 is configured to transmit acceleration data measured by the second accelerometer 6 to a site of collection of acceleration data from both accelerometers, such as to a device 11 arranged in said first train unit 5. It is shown how radio antennas 12, 13 are arranged on the first train unit 5 and the last train unit 7 for transferring acceleration data between these through a radio link.

[0022] The device 11 is configured to compare acceleration data collected from the first accelerometer 4 with acceleration data collected from the second accelerometer 6 and to determine that the train is complete if the comparison shows that said data are the same and that at least the last train unit is lost when said data differ.

[0023] Fig. 2 illustrates schematically how a method for monitoring and determining the completeness of the train is carried out. The second accelerometer 6 measures accelerations, which may of course also have a negative sign when the velocity of the entire train or of a part of the train lost is reduced, and the acceleration data so obtained is brought to pass through a decimation filter 14 for data compression and filtering of the data therefrom and then sent through a radio link 15 to the device 11 on board the first train unit, where the first accelerometer 4 measures the acceleration of the first train unit 5 and through a decimation filter 16 sends the acceleration data so obtained further to the device 11 where the acceleration data from the first accelerometer 4 are compared in a part 17 with the acceleration data from the second accelerometer 6. Based on the result of this comparison the train integrity is evaluated and determined in a part 18 of the device. The acceleration data so measured by the two accelerometers 4, 6 will be nearly identical as long as the train is complete, but as soon as any of the train units start to drift apart the acceleration data obtained through the second accelerometer will differ substantially from the acceleration data measured by the first accelerometer 4, so that the occurrence of such a loss will be immediately detected.

[0024] Fig. 3 illustrates an arrangement according to a second embodiment of the invention only differing from the first by having two second accelerometers 6, 6' arranged on the last unit 7 of the train. The two second accelerometers are preferably included in the same said portable member, but they may also be separately arranged in a portable member each. These two second accelerometers 6, 6' will then send acceleration data obtained therethrough to said device 11, which will compare acceleration data obtained by these two accelerometers with acceleration data obtained by the first accelerometer 4 and to determine that the train is complete if the comparison shows that acceleration data from one of the second accelerometers 6, 6' are the same as those from the first accelerometer, since would the last train unit be lost no one of the second accelerometers could show the same acceleration data as the first accelerometer even if the second accelerometers were defect. Thus, would one of the second accelerometers be defect, which means that it will show another acceleration than measured by the first accelerometer even if the train is complete, the other second accelerometer may then verify that the train is complete, and when also this accelerometer delivers acceleration data differing from the acceleration data delivered by the first accelerometer it may be determined that the last train unit is lost. The first accelerometer may then also be doubled, since a typical failure mode may be that acceleration measurement is stuck at zero. If the first train unit (loco) has only one accelerometer, letting the cars in the yard when accelerating would then cause a hazard.

[0025] The invention is of course in no way restricted to the embodiments described above, since many possibilities for modifications thereof are likely to be obvious to one skilled in the art without having to deviate from the scope of invention defined in the appended claims.

[0026] It is indicated in Fig. 1 how it would be possible to arrange a said third accelerometer 20 on the second last train unit 19.

[0027] It is pointed out that an arrangement according to the invention may be interesting to use also when track circuits are applied on the track sections for earlier discover that any train unit is lost.

[0028] The acceleration measurement could be complemented with occasional position measurements to detect very slow separations. These position measurements do not need to be frequent, because the lower the acceleration difference is, the longer it takes until a substantial distance between train parts accumulates. For the safe determination of the train position by wayside control devices or other trains, this can be considered, i.e. worst-case separations between position measurements.

Claims

1. A method for monitoring and determining the completeness of a train (1) of a plurality of interconnected units (2) moving along a railway track,
characterized by

a) measuring train unit accelerations by a first accelerometer (4) on board a train unit (5) being at the front of the train and by a second accelerometer (6, 6') on board a train unit (7) being the last as seen in the moving direction of the train,

b) comparing acceleration data obtained by said first accelerometer (4) and relating to the front train unit (5) with acceleration data obtained by said second accelerometer (6, 6') and relating to the last train unit (7), and

c) determining that the train is complete if the comparison of acceleration data shows that said data are the same and that at least the last train unit is lost when said data differ.

2. A method according to claim 1, characterized in that in step a) the acceleration of the last train unit (7) is measured by two said second accelerometers (6, 6') on board the last train unit (7), that in step b) acceleration data obtained by both said second accelerometers are compared with the acceleration data obtained by the first accelerometer (4), and that in step c) it is determined that the train is complete if the comparison shows that acceleration data from one of the second accelerometers (6, 6') are the same as those from the first accelerometer (4).

3. A method according to claim 1 or 2, characterized in that in step a) also the acceleration of the second last train unit (19) is measured by a third accelerometer (20) and in step c) these acceleration data are compared with the acceleration data obtained by the first accelerometer (4), and that it is in step c) determined that when the acceleration data obtained by the third accelerometer (20) differ from the acceleration data obtained by the first accelerometer (4) at least two train units are lost.

4. A method according to any of the preceding claims, characterized in that an alarm is emitted if it is in step c) determined that at least the last train unit (7) is lost.

5. An arrangement for monitoring and determining the completeness of a train (1) of a plurality of interconnected units (2) moving along a railway track,
characterized in that the arrangement comprises:

• a first accelerometer (4) configured to be arranged on board a front unit (5) of a train as seen in the intended moving direction of the train and to measure accelerations of the front train unit,

• a second accelerometer (6, 6') configured to be arranged on board a last train unit (7) as seen in the intended moving direction of the train and to measure accelerations of the last train unit,

• at least one transmitter (8) associated with one of said accelerometers (4, 6, 6') to transmit acceleration data measured thereby to a site of collection of acceleration data from both accelerometers, and

• a device (11) configured to compare acceleration data collected from the first accelerometer (4) with acceleration data collected from the second accelerometer (6, 6') and to determine that the train is complete if the comparison shows that said data are the same and that at least the last train unit (7) is lost when said data differ.

6. An arrangement according to claim 5, characterized in that said device (11) is associated with one of said accelerometers (4, 6, 6'), and that said transmitter (8) is configured to send acceleration data from the other accelerometer through a radio link (15) to said device (11) for said comparison.

7. An arrangement according to claim 6, characterized in that said device (11) is configured to be arranged on board said front train unit (5) in connection with said first accelerometer (4), and that said transmitter (8) is associated with the second accelerometer (6, 6').

8. An arrangement according to any of claims 5-7, characterized in that at least one of the first (4) and second (6, 6') accelerometers is included in a portable member (9) being moveable from one train unit to another.

9. An arrangement according to claim 7 and 8, characterized in that the second accelerometer (6, 6') and the transmitter (8) associated therewith are included in a said portable member (9).

10. An arrangement according to any of claims 5-9, characterized in that it comprises two said second accelerometers (6, 6') configured to be arranged on board a last train unit (7) and to measure acceleration of this train unit, and that said device (11) is configured to compare acceleration data obtained by both said second accelerometers (6, 6') with acceleration data obtained by said first accelerometer (4) and to determine that the train is complete if the comparison shows that acceleration data from one of the second accelerometers (6, 6') are the same as those from the first accelerometer (4).

Drawing