WO2005118366A1 - Processing of railway track data - Google Patents
Processing of railway track data Download PDFInfo
- Publication number
- WO2005118366A1 WO2005118366A1 PCT/GB2005/001600 GB2005001600W WO2005118366A1 WO 2005118366 A1 WO2005118366 A1 WO 2005118366A1 GB 2005001600 W GB2005001600 W GB 2005001600W WO 2005118366 A1 WO2005118366 A1 WO 2005118366A1
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- WO
- WIPO (PCT)
- Prior art keywords
- data
- sample
- transfer function
- track
- stored
- Prior art date
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B61—RAILWAYS
- B61K—AUXILIARY EQUIPMENT SPECIALLY ADAPTED FOR RAILWAYS, NOT OTHERWISE PROVIDED FOR
- B61K9/00—Railway vehicle profile gauges; Detecting or indicating overheating of components; Apparatus on locomotives or cars to indicate bad track sections; General design of track recording vehicles
- B61K9/08—Measuring installations for surveying permanent way
Definitions
- This invention relates to an apparatus and a method for processing data, in particular data obtained by monitoring a railway track, such data for example being used for assessing the quality of the track.
- Track recording vehicles are known, which are used in surveying a railway track to provide data representing the undulations of the rails in the vertical and horizontal planes, and their curvature.
- Software packages are also available, for example a software product under the trade mark VAMPIRE (from AEA Technology pic) , for predicting how a particular vehicle will respond when travelling at a particular speed along a track; such software packages, which may be referred to as vehicle dynamics simulations, require input data providing an undistorted representation of the track.
- VAMPIRE from AEA Technology pic
- vehicle dynamics simulations require input data providing an undistorted representation of the track.
- the raw data obtained by the sensors on a track recording vehicle provide information about train movement, and can be processed to determine track data, in particular being filtered to distinguish between short wavelength data and long wavelength data. This filtration process may introduce phase differences.
- a method of obtaining data on the quality of a railway track comprising: a) receiving from a track recording vehicle data concerning variations of a parameter, the data comprising samples, obtained in either the spatial or the temporal domain, which have been subjected to a filtration process having an associated transfer function (H) ; b) selecting a transfer function H ⁇ which inverts at least the phase differences of the transfer function H of the filter; c) temporarily storing a multiplicity (N) of sequentially-received samples in a memory, each said sample being stored with an indication of the corresponding position or time; d) generating an output data sample by calculating the integral of the product of the stored data samples with an impulse function (F) , wherein the impulse function is deduced from the selected transfer function H ⁇ according to the equation:
- time (t) is the appropriate variable, or, if expressed in terms of distance (s) :
- the multiplicity (N) is an odd number; and preferably the impulse function is centred on the middle sample of those stored, that is ((N+l)/2) th sample if N is odd.
- the impulse function need not be a symmetrical function; it is ⁇ centred' in the sense that it is a function not of absolute time (or distance) but of the time (or distance) relative to that of a specific stored sample. The method described above enables a series of output data samples to be generated substantially in real-time, the only delay being that taken for the receipt of ((N+l)/2) samples.
- This method may be performed within a track recording vehicle. For example it can enable amplitude and phase distortions of track geometry signals to be removed, so that the corrected signals can be used as input for a vehicle dynamics simulation. Another application is that, once amplitude and phase distortions of track geometry signals have been removed, the signals correctly represent the shape of track features such as dipped rail joints, and so can be used to guide track maintenance.
- the method of the invention can also remove distortions due to anti-aliasing filters.
- the present invention also provides an apparatus for performing this method.
- the method of the invention may be used to provide input data to a vehicle dynamics simulator carried in a track recording vehicle, so that the simulator can deduce the risk of derailment of a particular type of vehicle in substantially real-time.
- the vehicle dynamics simulator could give a warning signal if the corresponding simulated vehicle would be derailed.
- the track survey vehicle can, substantially in real-time, provide warnings of track sections that would give high derailment risk for a particular type of vehicle at a particular speed.
- Warnings might also be given if the simulated vehicle would subject passengers to unacceptable jolts, or if the simulated vehicle would subject the portion of track to unacceptable track forces, and such information could also be reported as soon as the vehicle has passed over that section of the track. This enables track maintenance to be targeted at those sections of track most in need of improvement.
- an apparatus incorporating the present invention is installed in a track recording vehicle 10, that is to say a rail vehicle incorporating transducers monitoring displacements and accelerations of the bogie and/or the body as the vehicle 10 moves along the track 11.
- a track recording vehicle 10 that is to say a rail vehicle incorporating transducers monitoring displacements and accelerations of the bogie and/or the body as the vehicle 10 moves along the track 11.
- transducers monitoring displacements and accelerations of the bogie and/or the body as the vehicle 10 moves along the track 11.
- it might incorporate an accelerometer monitoring vertical accelerations of the bogie, and a displacement transducer monitoring vertical displacement of the axle relative to the bogie; data from such transducers would enable undulations in the vertical plane of each rail of the track to be monitored.
- accelerometers measuring horizontal accelerations, along with a displacement transducer to monitor the wheel relative to the bogie enable undulations of the track in the horizontal plane to be monitored.
- Track recording vehicles normally incorporate several different transducers, data from the transducers being sampled every 1/8 m and digitized, and the output data may involve calculations that combine data from several such transducers.
- the data is subjected to signal processing (represented diagrammatically by box 12) that includes filtration so as to generate track data, which would typically be displayed to an operator, for example using a graphical interface, and stored for subsequent processing.
- signal processing represented diagrammatically by box 12
- the data may also be stored in conjunction with data from other sensors, for example positional data from a GPS sensor.
- the data typically would represent alignment (a measure of the offset of the rails from the required smooth curve, measured in mm) , and curvature (indicating the reciprocal of the radius of the curve followed by the track, measured in km -1 ) .
- the cutoff wavelength is set at 70 m, horizontal displacements of shorter wavelength than this being treated as alignment, and horizontal displacements of longer wavelength being treated as curvature.
- the data typically would represent "top” (a measure of the displacement of the rails from the required smooth curve, measured in mm) , and gradient (indicating the slope of the track, in mm/mm) .
- the cutoff wavelength in this case is typically also set to 70 m.
- the track data streams from the processor 12 representing alignment, curvature, and top (and possibly also gradient) , and possibly other data streams such as positional information are transmitted to a data post-processing server 14, and thence to a reporting server 16, and so to various display interfaces 18 and to a data store 20.
- Data streams representing alignment, curvature, and top (and possibly also gradient) are also supplied by the post-processing server 14 to several different vehicle dynamics modules 22 (three such modules are represented) .
- Each such module 22 consists of a microprocessor arranged to model the dynamics of a particular vehicle travelling along the track 11 at a particular speed. The output of these vehicle dynamics modules 22 is fed back to the data post-processing server 14, and is supplied to the reporting server 16 along with the corresponding track data (processed as described below) .
- the processor 12 is used to separate high frequency (short wavelength) components from low frequency (long wavelength) components.
- Analogue filters or digital infinite impulse response (IIR) filters can perform these tasks efficiently, but they introduce distortion. Methods are known to eliminate this phase distortion, either avoiding it by using finite impulse response (FIR) filters instead of IIR filters, or by back filtering the already distorted data with an identical IIR filter to restore the original phase content.
- FIR finite impulse response
- the server 14 performs signal shaping of the incoming data, and forwards it to the rest of the system for storage and/or further processing.
- the signal processing method can deal with both spatially and temporally sampled data streams. It can also perform 'cross-domain' operations, as well, that is to say to perform temporally defined operations in spatially sampled (taken at equal distances) data, and vice versa.
- the server 14 consists of: - Digital input and output interfaces - A buffer memory to store N samples of the data stream, including the measured value and a time or distance stamp, indicating the time or distance the measurement was taken.
- the type of the stamp data depends on the actual operation: if temporal operation is needed, then time stamp, if spatial operation is needed the distance stamp has to be attached to each measured value.
- the actual sampling method does not affect the operation of the filter. For example, usually the measurements are taken at equal distances, so if the vehicle speed is increasing, then the differences between the consecutive time stamps will decrease, but the system operation will not change.
- - Memory to store the parameters of the calculations.
- Arithmetic processing capability is possible to store the parameters of the calculations.
- the details such as the data transfer protocols, memory type etc. must be adjusted to the system in which the server 14 is used. In certain cases it may be a separate instrument connected to the data bus of the measurement system, in other cases it may be fully integrated into the measurement system.
- the operation of the server 14 is as follows: 1.
- the samples of the incoming data are stored in an N- element first-in-first-out (FIFO) buffer, which is initialized with zeros as measured values .
- FIFO first-in-first-out
- Each new sample enters the first slot of the buffer, moving the previous measurements one slot forward.
- the data that had been in the N th slot is deleted, since it is replaced by the one coming from the (N-l) th slot.
- N is preferably odd.
- Y(T 0 ) is the output data, time stamped as taken at T 0 .
- T 0 is the actual time stamp of the ((N+l)/2) th data in the buffer. In a certain sense, the calculation above is centred on T 0 , and the output data stream is always delayed by (N+l)/2 samples.
- Ti is the time stamp of the oldest (N th ) data in the buffer.
- T 2 is the time stamp of the latest (1 st ) data in the buffer. It is also true, that ! ⁇ To ⁇ T 2 .
- X(t) is the data stream stored in the buffer.
- F(t) is the finite impulse function, derived from the desired restoration.
- F(t) is integratable between any possible t values.
- Equation 1 which is expressed above as an integral (implying continuous functions), must in practice be performed as a summation, by a suitable discrete calculation method. Since each sample is processed separately, and has an associated time stamp, if the time intervals or spatial distances between successive samples vary, or there are randomly missing samples, overall operation is not affected. This is a significant advantage. Eq. 1 is shown in the temporal domain. The formula is still valid in the spatial domain, where the time values have to be replaced with distance values:
- the calculated output is forwarded for further processing.
- the operation clearly depends on correctly determining the impulse function, F(t) or F(s).
- the impulse function is defined from the desired system behaviour, described by a transfer function. Transfer functions are complex equations that describe the system behaviour as a function of the cyclic frequency, ⁇ . If H(j ⁇ ) is the transfer function of a filter, then:
- H(j ⁇ ) I is the ratio of the output to the input amplitude
- ⁇ (H(j ⁇ )) is angle of the phase delay, where j is the square root of -1.
- Example 1 Restoring the original phase content of an anti-aliased signal
- a track recording vehicle 10 will include various transducers which measure aspects of the vehicle movement, such as an accelerometer, gyroscope etc.
- the signal from such a transducer which is an analogue signal
- an anti-aliasing filter is low frequency pass analogue filters, eliminating the undesired frequency content.
- the data processor 12 would then produce digital output signals by sampling the analogue signal at equal distances along the track.
- Anti-aliasing is essential, but it introduces a non-linear phase delay of the incoming signal. This phase delay will distort the shape of the signal, until now back-filtering was only the way to restore the original phase content. However, back- filtering changes the amplitudes in the transition band and cannot be used if the results are needed in real time.
- the transfer function H of the analogue antialiasing filter can be given by the amplitude and phase responses as a function of the cyclic frequency:
- Example 2 Restoring broadband curvature signal from asymmetric versine input
- curvature It is difficult to measure curvature directly, so different indirect methods are used.
- One of them is asymmetric versine; the asymmetric versine, v, is measured by considering a fixed length chord between two points on the rail. The chord is divided by a point Y into two unequal parts, Li and L 2 , and v is the distance of the rail from the point Y measured along a line perpendicular to the chord.
- Asymmetric versine is easy to measure both manually and automatically. It gives a broadband description of the lateral track geometry, recording both short and long wavelengths components in the same output.
- a complicated transfer function is required, which also introduces phase distortion.
- Previously-known methods were unable to give a proper reconstruction of curvature from versine in real time.
- the server 14 can be configured to reproduce broadband curvature from digital asymmetric versine input in real time.
- a track recording vehicle 10 might include several such vehicle dynamics modules 22 operating in parallel, for example twelve rather than the three modules 22 shown here. Operation of this one vehicle 10 is therefore equivalent to running a fleet of a dozen different vehicles that may use this particular route, each at their own speed, and each of the virtual vehicles is effectively instrumented for assessing the risk of derailment, and also other parameters such as passenger comfort, track forces, vehicle kinematic movements etc..
- This information is obtained in real-time, and is reported as part of the data provided to the display interfaces 18 as soon as the track recording vehicle 10 has passed over a portion of the track 11.
- the information is embedded in the same stream of data as the information on track geometry. Hence it can be readily interfaced to track management software .
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP05738223A EP1771327A1 (en) | 2004-06-02 | 2005-04-28 | Processing of railway track data |
CA002573435A CA2573435A1 (en) | 2004-06-02 | 2005-04-28 | Processing of railway track data |
AU2005249761A AU2005249761A1 (en) | 2004-06-02 | 2005-04-28 | Processing of railway track data |
US11/628,311 US20070246612A1 (en) | 2004-06-02 | 2005-04-28 | Processing of Railway Track Data |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0412215.6 | 2004-06-02 | ||
GBGB0412215.6A GB0412215D0 (en) | 2004-06-02 | 2004-06-02 | Processing of railway track data |
Publications (1)
Publication Number | Publication Date |
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WO2005118366A1 true WO2005118366A1 (en) | 2005-12-15 |
Family
ID=32696471
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB2005/001600 WO2005118366A1 (en) | 2004-06-02 | 2005-04-28 | Processing of railway track data |
Country Status (6)
Country | Link |
---|---|
US (1) | US20070246612A1 (en) |
EP (1) | EP1771327A1 (en) |
AU (1) | AU2005249761A1 (en) |
CA (1) | CA2573435A1 (en) |
GB (1) | GB0412215D0 (en) |
WO (1) | WO2005118366A1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3042823A1 (en) * | 2015-01-08 | 2016-07-13 | SmartDrive Systems, Inc. | System and method for aggregation display and analysis of rail vehicle event information |
US9663127B2 (en) | 2014-10-28 | 2017-05-30 | Smartdrive Systems, Inc. | Rail vehicle event detection and recording system |
US9902410B2 (en) | 2015-01-08 | 2018-02-27 | Smartdrive Systems, Inc. | System and method for synthesizing rail vehicle event information |
US9908546B2 (en) | 2015-01-12 | 2018-03-06 | Smartdrive Systems, Inc. | Rail vehicle event triggering system and method |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB0601819D0 (en) * | 2006-01-31 | 2006-03-08 | Aea Technology Plc | Track twist monitoring |
CN102353717B (en) * | 2011-06-28 | 2013-03-13 | 哈尔滨工业大学 | Detection apparatus and method for steel rail failures based on characteristics of non-negative tensor resolution |
AU2018246236B2 (en) * | 2017-03-27 | 2023-11-30 | Harsco Technologies LLC | Track geometry measurement system with inertial measurement |
AT521420A1 (en) * | 2018-07-11 | 2020-01-15 | Plasser & Theurer Export Von Bahnbaumaschinen Gmbh | Method and system for monitoring a track |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
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EP0697672A2 (en) * | 1994-08-19 | 1996-02-21 | MAN Technologie Aktiengesellschaft | Procedure to correct a measurement curve or a signal variation, system for carrying out the method, and use for reconstruction of the error position in railway tracks by means of geometrical relative measurements |
WO2004009422A1 (en) * | 2002-07-19 | 2004-01-29 | Aea Technology Plc | Assessment of railway track geometry |
Family Cites Families (8)
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US4760797A (en) * | 1985-02-20 | 1988-08-02 | Southern Railway Company | Method and apparatus for automated tie detection and tamping |
US5358202A (en) * | 1992-07-21 | 1994-10-25 | Consolidated Rail Corporation | Cab signal track code analyzer system |
US5768317A (en) * | 1995-05-08 | 1998-06-16 | National Semiconductor Corporation | Equalization filter compensating for distortion in a surface acoustic wave device |
US6424150B2 (en) * | 1999-03-17 | 2002-07-23 | Southwest Research Institute | Magnetostrictive sensor rail inspection system |
DE19704598C1 (en) * | 1997-02-07 | 1998-06-18 | Bruker Analytische Messtechnik | Process for obtaining an optical FT spectrum |
US6715354B2 (en) * | 1998-02-24 | 2004-04-06 | Massachusetts Institute Of Technology | Flaw detection system using acoustic doppler effect |
EP1134945B1 (en) * | 2000-03-07 | 2008-05-14 | Alcatel Lucent | Method to determine a channel characteristic and discrete wavelet receiver to perform the method |
TW577207B (en) * | 2002-09-17 | 2004-02-21 | Via Tech Inc | Method and circuit adapted for blind equalizer |
-
2004
- 2004-06-02 GB GBGB0412215.6A patent/GB0412215D0/en not_active Ceased
-
2005
- 2005-04-28 AU AU2005249761A patent/AU2005249761A1/en not_active Abandoned
- 2005-04-28 EP EP05738223A patent/EP1771327A1/en not_active Withdrawn
- 2005-04-28 WO PCT/GB2005/001600 patent/WO2005118366A1/en not_active Application Discontinuation
- 2005-04-28 CA CA002573435A patent/CA2573435A1/en not_active Abandoned
- 2005-04-28 US US11/628,311 patent/US20070246612A1/en not_active Abandoned
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0697672A2 (en) * | 1994-08-19 | 1996-02-21 | MAN Technologie Aktiengesellschaft | Procedure to correct a measurement curve or a signal variation, system for carrying out the method, and use for reconstruction of the error position in railway tracks by means of geometrical relative measurements |
WO2004009422A1 (en) * | 2002-07-19 | 2004-01-29 | Aea Technology Plc | Assessment of railway track geometry |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9663127B2 (en) | 2014-10-28 | 2017-05-30 | Smartdrive Systems, Inc. | Rail vehicle event detection and recording system |
EP3042823A1 (en) * | 2015-01-08 | 2016-07-13 | SmartDrive Systems, Inc. | System and method for aggregation display and analysis of rail vehicle event information |
US9487222B2 (en) | 2015-01-08 | 2016-11-08 | Smartdrive Systems, Inc. | System and method for aggregation display and analysis of rail vehicle event information |
US9902410B2 (en) | 2015-01-08 | 2018-02-27 | Smartdrive Systems, Inc. | System and method for synthesizing rail vehicle event information |
US9981674B1 (en) | 2015-01-08 | 2018-05-29 | Smartdrive Systems, Inc. | System and method for aggregation display and analysis of rail vehicle event information |
US9908546B2 (en) | 2015-01-12 | 2018-03-06 | Smartdrive Systems, Inc. | Rail vehicle event triggering system and method |
Also Published As
Publication number | Publication date |
---|---|
AU2005249761A1 (en) | 2005-12-15 |
CA2573435A1 (en) | 2005-12-15 |
US20070246612A1 (en) | 2007-10-25 |
EP1771327A1 (en) | 2007-04-11 |
GB0412215D0 (en) | 2004-07-07 |
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