WO1997011872A1

WO1997011872A1 - Method and apparatus for monitoring track condition

Info

Publication number: WO1997011872A1
Application number: PCT/GB1996/002379
Authority: WO
Inventors: Edwin Charles Bovey
Original assignee: London Underground Limited
Priority date: 1995-09-26
Filing date: 1996-09-26
Publication date: 1997-04-03
Also published as: AU7136996A; GB2305796A; GB9519562D0

Abstract

The condition of a route-way, e.g. a railway track is recorded by an apparatus which includes a video camera or cameras (32, 34) which are mounted underneath a vehicle (10) which runs on the track (12, 19). Signals from the video camera are recorded by one or more recorders (28, 26) and the recorded data includes information relating to the tool location associated with the signals. The recorded signal can be processed and analysed subsequently to provide information relating to the track condition.

Description

METHOD AND APPARATUS FOR MONITORING TRACK CONDITION

The present invention relates to a method and apparatus for recording the condition of a route-way on which a vehicle travels. It has particular utility in the inspection of the running rails and associated equipment of a railway.

Hitherto, the inspection of railway lines has been carried out manually by railway personnel. For example, in a suburban rail network, a maintenance crew will walk a given section of track every two to three days, and inspect each rail joint, key, etc. to ensure that it is in good order. This results in track inspection being a time-consuming and costly exercise. In addition, if the inspection is carried out at a time when trains are running along the track or a nearby track, then there is a danger to the maintenance crew both from moving trains and from any conductor rails which are present. These hazards can be avoided by inspecting the track at a time when trains are not running on the tracks. However, this often results in the inspection work being done in unpleasant conditions during unsociable hours. Hence, the cost and duration of the track inspection increases still further. A further disadvantage of known methods of track inspection is that little use is made of the results of previous inspections on a subsequent inspection. For example, a non-critical fault discovered on one inspection may not be specifically re-checked on a later inspection. Hence, the fault can develop into a critical one before it is noticed, and result in a delay in train services operating on the track. Also, a persistent problem at a specific location along the railway may not be recognised as such.

It is the object of the present invention to alleviate some or all of the above-mentioned problems.

According to a first aspect of the present invention there is provided an apparatus for recording the condition of a route-way along which a vehicle travels, said apparatus comprising: one or more video cameras; means for mounting said cameras to the vehicle; means for providing a location signal indicative of the location of said vehicle along said route-way; means for recording each video field output by the camera; means for recording the location signal; and means for processing said location signal so as to attribute a location to each recorded video field; whereby on playing back the recorded signal, a video image of one or more chosen locations on said route-way can be inspected in order to determine the condition of the route-way at that location.

The apparatus of the present invention may be attached to a train which runs in a normal timetabled slot. Clearly, the need to walk along the tracks is obviated. This results in the track inspection being less time-consuming than has hitherto been possible. In addition, the use of an apparatus according to the present invention allows the inspection of the track to be made in comfortable surroundings at a convenient time. This results in a reduction in the cost of the track inspection.

Another advantage of the apparatus is that a 24-hour train service may be provided, there being no requirement for the service to be suspended whilst inspection of the tracks takes place.

Preferably, the apparatus further comprises one or more illumination means for illuminating the field of view of the video camera for a predetermined time interval and a synchronisation means for controlling the illumination means such that illumination is provided during an image-forming time interval of the camera.

This arrangement has the advantage that the image- forming time interval of the camera may be kept short, such that speed of the vehicle does not result in a blurring of the image formed at the video camera.

Advantageously, said predetermined time interval is shorter than the minimum image-forming time interval of the camera and the illumination interval occurs within said minimum image-forming time interval.

This arrangement has the advantage that the image formed at the video camera is not blurred even if the vehicle which carries the video camera moves a significant distance within the minimum image-forming time interval of the camera.

Preferably, said apparatus further comprises one or more microphones for recording acoustic signals, and means for mounting said microphones onto the vehicle, and the means for recording the video signal is also arranged to record the acoustic signal. This has the advantage that a fault which has a more recognisable acoustic effect than visual effect (e.g. a partially loosened bolt) may be more easily identified.

Advantageously, said apparatus further comprises one or more vibration measuring transducer means .

Preferably, said video cameras include one or more thermal imaging cameras .

This has the advantage that any fault which has a more recognisable thermal effect than other physical effect may be more easily identified.

According to a second aspect of the present invention there is provided a vehicle for recording the condition of a route-way along which the vehicle travels including an apparatus as set forth above.

According to a third aspect of the present invention there is provided a method of determining the condition of a route-way along which a vehicle travels, said method comprising the steps of: using a video camera to provide images of said route-way at locations along said route-way; providing a signal indicative of the location of each image; recording said image; recording said location indicating signal; processing said location indicating signal to attribute a location to each video image; and playing-back the image of one or more chosen locations .

Preferably, said method further comprises the steps of illuminating the field of view of the video camera for a predetermined time interval and controlling the illumination such that it is provided during an image- forming time interval of said video camera.

Advantageously, said predetermined time interval is shorter than the minimum image-forming time interval of said video camera and said illumination is provided throughout an illumination interval which falls within said minimum image-forming time interval.

Advantageously, said method further comprises the step of recording an acoustic signal together with said video signal. Other examples of signal types and sources that may be recorded are vibration and automatic train operation (ATO) signals.

Preferably, said method further comprises the step of analysing said acoustic data to recognise an acoustic signature associated with a given type of fault in the route-way.

Advantageously, neural network software is utilised to analyze the visual and/or acoustic data.

This has the advantage that the probability of a correct identification of a fault in the route-way is enhanced.

Advantageously, said method further comprises the step of creating a database containing information giving the location of given types of features along the route- way.

This has the advantage of enabling the selection of those images which contain a given feature.

There now follows a detailed description, given by way of example only, of a specific embodiment of the present invention. This description is given with reference to the accompanying drawings in which:

Figure 1 is a schematic plan view of a train unit carrying an automatic video inspection system;

Figure 2 is a schematic cross-section along line 2-2 of Figure 1;

Figure 3 is a schematic diagram showing the flow of signals between components of the inspection system;

Figure 4 is a chart showing the timing of the operations of the components in the inspection system.

Figure 1 shows the front portion of a train unit comprising a driven car (10) and a first trailer car (11). The driven car (10) has driven axles (6,7,8,9) which run along two running rails (12,14). The trailer car also has four axles, only the leading two of which (19,21) are shown. Power for both driving the unit and for supplying other electrical loads within the unit is supplied between two conductor rails (16,18) which run parallel to the running rails . Appropriate electric pick-up devices (not shown) are used to connect the electrical systems of the unit to the conductor rails (16,18). The driven car has a driver's cab (20) which extends rearwardly from the forward end of the car for about one-tenth of its length.

The cab (20) contains four S-VHS video tape recorders (22,24,26,28) and a PC (30), a synchronisation signal generating circuit (50) and various power supply components (also not shown) . The power supply components include an inverter for converting the train's 50V DC auxiliary supply to 240V AC, a circuit providing 24V DC, and two strobe power supply units, each providing a 2.5kV supply and trigger signals . The remainder of the carriage is arranged to transport passengers in the normal way.

It is the aim of the automatic video inspection system to investigate many different features of the track. Examples include rail joints (11), rail keys (13), rail chairs ( 13A) and the bolts connecting the rail chairs to sleepers (not shown). Other features such as the insulator pots (15) supporting the conductor rails, the expansion joints between sections of rail and greasers for lubricating the gauge face of the high rail on tight bends may also be investigated by the inspection system. The left-hand side of Figure 2 shows a first pair of micro-cameras (32,34) which are mounted directly underneath the trailer car (11) at a position about 1.5m behind the second foremost axle (21) of the trailer car. The cameras (32,34) are spaced and angled so that each camera views a respective side of the left-hand running rail (14). The micro-cameras are substantially cylindrical and have, when placed in their housing, a length of about 200mm and a diameter of about 40mm. Each camera (32,34) contains a Charge Coupled Device and has its image-forming period set to a minimum value, in this case 1ms. The cameras (32,34) are each provided with an external connection which is connected to the synchronization signal generator (50) provided in the driver's cab. The video signals output by each camera are in accordance with the S-Video standard and are fed by means coaxial cables (35) to a respective one of the video recorders (26,28). For reasons to be explained below, each micro-camera (32,34) is provided with an aperture stop.

Three stroboscopic lights (38) are positioned directly underneath the chassis of the carriage. The lights (38) are arranged in a line across the width of the carriage at a position around 1.5m behind the second foremost axle (21) of the trailer car. The stroboscopic lights (38) are connected to a synchronization pulse adaptor (not shown) which is itself connected to the synchronisation signal generator (50) . The strobe lights (38) are arranged to produce a very high light level (approximately 10⁵ lux) for a very short time interval of around 16 to 20μs. The strobe lights (38) all face in the same direction along the rail and are positioned so as to provide illumination for both the left and right pairs of micro-cameras (32,33,34,35).

The central strobe light is connected to one of the two strobe power supply units and, when triggered, is powered at full power. The two outer strobe lights are connected to the other power supply units and, when triggered, are powered at half-power.

The micro-cameras (32) are also provided with microphones (40), acoustic signals from which are recorded on one or more of the video tape recorders (22,24,26,28).

On the right-hand side of the carriage, the second foremost axle (21) is provided with a tachometer (42) which outputs 200 pulses for every revolution of the axle (21). A connection is provided between the tachometer (42) and a respective audio input of two of the video cassette recorders (22,28).

The flow of signals between the components of the apparatus and the operation of the apparatus will now be described with reference to Figures 3 and 4.

As stated above, the strobe lights (38) produce a burst of light of high intensity. However, the amount of light reaching the CCD is limited by the presence of an aperture stop in each micro-camera (32,33,34,35) . The aperture stop substantially prevents the normal light levels present during the remainder of the image-forming interval from affecting the CCD. Hence, the image at the CCD is substantially formed only during the operation of the strobe lights (38).

The advantage of this arrangement is that the image formed at each video camera (32,33,34,35) results only from the light received at the video camera (32,33,34,35) during the short illumination interval referred to above rather than the longer image-forming interval. It will be appreciated that a suburban train typically travelling at 20ms^"1 will move 20mm within a shutter open interval of 1ms, but will only move 0.4mm in the short illumination interval of 20μs. Therefore, by providing the video cameras (32,33,34,35) with an aperture stop, blurring of the recorded image can be avoided.

To initiate the operation of the inspection system, the software on the PC (30) is run and the unit carrying the auto-video inspection apparatus is run along the track to be investigated. On a command being issued to the PC by an operator in the driver's cab, all four video recorders (22,24,26,28) are started simultaneously.

At the same time, the synchronisation signal generator (50) starts to output a "black burst" signal. This signal is simultaneously transmitted to each micro-camera (32,33,34,35) and also to the synchronisation pulse adaptor associated with the three stroboscopic lights (38) . Each camera locks its internal circuits to the black burst signal and through an adjustable delay the synchronisation pulse adaptor provides trigger pulses to the two strobe power supply units. The two strobe power supply units then cause the strobe lights (38) to fire during the image-forming period of the microcameras (32,33,34,35) . It will be realised that the strobes and cameras are triggered at a rate of 50 times a second. Each image captured by each micro-camera (32,33,34,35) is recorded on the video track on one of the video tape recorders. In addition to the video information, the tachometer pulses are recorded on an audio track of two of the video cassette recorders (22,28). It will be realised by those skilled in the art that each recorded video frame will have a frame number recorded with it. This sequence of capturing the image and recording it is repeated until the train stops at a station.

Once the train has stopped at a station the operator presses a key on the PC to indicate that the train has stopped at a station. A message on the screen of the PC (30) suggests a station name selected from stored information representing the route of the train. The operator then confirms or corrects this. The PC stores the video frame number to be associated with that station stop.

The unit is then run to the next station along the line and the above operation is repeated. At the end of the auto-video inspection of track a command is issued to the PC (30) which results in each of the video recorders (22,24,26,28) stopping their recording operation.

Once the unit has been run along the section of track to be investigated, the video tapes are unloaded from the video recorders (22,24,26,28) and are analysed by another computer. This computer counts the tachometer pulses which are associated with each 40ms period associated with each video frame and creates a file which stores the number of tachometer pulses associated with each frame number.

Since the frame numbers associated with each station stop have been recorded by the PC (30) on board the unit, the total number of tachometer counts between two stations can easily be found. Since the distance between any two stations is well known, the tachometer can thereafter be calibrated. This has the advantage that the diameter of the wheel connected to the axle (21) need not be accurately measured in order to calibrate the tachometer.

Alternatively, marker plates placed within the field of vision of the cameras and at accurately known locations along the track may be used to calibrate the apparatus. In this case, the video images containing marker plates are identified and the respective frame numbers recorded. Since the distance between the two marker plates is accurately known, the tachometer can be calibrated. Furthermore, this latter method of calibration has the advantage that the distance between the marker plates is fixed whereas the point at which a driver stops a train within a station may vary slightly.

Once the tachometer has been calibrated, a further file is created by the computer which stores for each frame number, the distance in metres from the previous station.

In order to help analyze the recorded data, the method of monitoring the condition of the track further includes the creation of a computer database which details the location, type and criticality of each railway feature. For example, the database stores the location of all "Monument Blocks" on a given section of track, and identifies the operation of these as being of low criticality. Therefore, on playing back the videotapes recorded during the travel of the carriage, only those frames which include features of, say, a high criticality can be selected for investigation. Hence, a report on the condition of critical railway features can be prepared quickly, investigation of the less critical features being carried out in due course.

One possible implementation of the present system might involve the analysis of the acoustic signals recorded by the microphone or signals recorded by a vibration sensor in order to recognise a fault condition. This type of analysis might be particularly suited to the detection of loose securing bolts which may result in the passage of the train causing a characteristic vibration or noise before visual detection of the looseness of the bolt is possible. In particular neural network analysis techniques might be used in order to enable the acoustic signatures of such faults to be recognised.

Although the above system has been described in relation to suburban trains, it is possible to implement the system for high speed trains. One problem which arises as the train speed increases is that the successive video fields recorded by the cameras will not show overlapping sections of track. This problem may be overcome by increasing the field of view of the cameras, or alternatively, by simply supplying further cameras at a spaced longitudinal position along the carriage.

Claims

CLAIMS ;

1. An apparatus for recording the condition of a route-way along which a vehicle travels, said apparatus comprising: one or more video cameras; means for mounting said cameras to the vehicle; means for providing a location signal indicative of the location of said vehicle along said route-way; means for recording each video field output by the camera; means for recording the location signal; and means for processing said location signal so as to attribute a location to each recorded video field; whereby on playing back the recorded signal, a video image of one or more chosen locations on said route-way can be inspected in order to determine the condition of the route-way at that location.

2. Apparatus according to claim 1, including one or more illumination means for illuminating the field of view of the video camera for a predetermined time interval and a synchronisation means for controlling the illumination means such that illumination is provided during an image-forming time interval of the camera.

3. Apparatus according to claim 2, wherein said predetermined time interval is shorter than the minimum image-forming time interval of the camera and the illumination interval occurs within said minimum image-forming time interval.

4. Apparatus according to any preceding claim, including one or more microphones for recording acoustic signals, and means for mounting said microphones onto the vehicle, and the means for recording the video signal is also arranged to record the acoustic signal.

5. Apparatus according to any preceding claim, including one or more vibration measuring transducer means.

6. Apparatus according to any preceding claim, wherein said video cameras include one or more thermal imaging cameras.

7. A vehicle for recording the condition of a route- way along which the vehicle travels including an apparatus according to any preceding claim.

8. A method of determining the condition of a route- way along which a vehicle travels, said method comprising the steps of: using a video camera to provide images of said route-way at locations along said route-way; providing a signal indicative of the location of each image; recording said image; recording said location indicating signal; processing said location indicating signal to attribute a location to each video image; and playing-back the image of one or more chosen locations.

9. A method according to claim 8, including the steps of illuminating the field of view of the video camera for a predetermined' time interval and controlling the illumination such that it is provided during an image-forming time interval of said video camera.

10. A method according to claim 9, wherein said predetermined time interval is shorter than the minimum image-forming time interval of said video camera and said illumination is provided throughout an illumination interval which falls within said minimum image-forming time interval.

11. A method according to any one of claims 8 to 10, including the step of recording an acoustic signal together with said video signal.

12. A method according to claim 11, including the step of analysing said acoustic data to recognise an acoustic signature associated with a given type of fault in the route-way.

13. A method according to claim 11 or claim 12, wherein neural network software is utilised to analyze the visual and/or acoustic data.

14. A method according to any one of claims 8 to 13, including the step of creating a database containing information giving the location of given types of features along the route-way.

15. Apparatus for recording the condition of a route- way along which a vehicle travels, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

16. A method for determining the condition of a route-way along which a vehicle travels substantially as hereinbefore described.