EP4251491B1 - Method and system for ascertaining correction values for correcting the position of a track - Google Patents

Description

technical field

The invention relates to a method for determining correction values for a position correction of a track, wherein an actual geometry of a track section is recorded by means of an inertial measuring device arranged on a measuring vehicle while the track is being traveled, and wherein measurement data of the recorded track section is output by the inertial measuring device to an evaluation device. The invention also relates to a system for carrying out the method.

State of the art

In the case of a ballasted track, the position of a track grid stored in the ballast bed is influenced by traffic and weather influences. To check the current geometry (track alignment) and especially before repair work, measurements are therefore regularly taken using a specially designed measuring vehicle. A suitably equipped track construction machine can also be used as a measuring vehicle. The track geometry is usually defined by the horizontal position (direction) and the vertical position (track inclination). To determine an absolute track geometry, the position relative to an external reference system is also required.

Known measuring methods use external reference points located next to the track, which are attached to fixed facilities such as electric masts. Such external reference points can be defined as marking bolts or other marking objects. The intended position of each external reference point on the track is documented in directories. In this way, the absolute track geometry is precisely defined on main railway lines (= design geometry of the track).

In addition, a target geometry of the track can be defined using internal references. The alignment is specified by a sequence of alignment elements in terms of their length and size. For straight lines, specifying one length is sufficient. Transition curves and curves are each specified by specifying a length and a curve size. So-called main track points indicate a change between different alignment elements, in particular for circular and transition curves as well as gradient breaks.

The horizontal position of the track is therefore made up of the track curvature as a sequence of straight sections, transition curves and circular arcs. The vertical position of the track is determined by the inclination and inclination changes including their rounding radii. The track's superelevation is defined by its superelevation sequence including superelevation ramps. When determining the track geometry, the superelevation and direction of the track are coordinated in accordance with the routing guidelines (e.g. EN 13803).

The restoration of a desired track position with high quality can be achieved with the so-called precision method. In this method, the exact, absolute track geometry (design geometry) is known through a sequence of defined alignment elements and the geothetic position of the main track points. Before a maintenance process, the existing track geometry and the track position are measured relative to defined reference points (fixed points). The measurement result is compared with the design geometry, with lifting and guide values for a track position correction being determined from a determined difference. This method is very precise and is suitable for high-speed lines that require optimized maintenance. The geometry parameters must be processed reliably and the geothetic reference points must be remeasured regularly.

For cost reasons, the so-called compensation method is used for routes with lower requirements. This method can be carried out without a known design geometry of the track. For example, a measuring system of a track tamping machine is used, in which Measuring chords (wandering chords) are stretched between measuring carriages guided on the track and serve as a reference system. Various forms of this wandering chord measuring principle can be found, for example, in the DE 10 2008 062 143 B3 or in the DE 103 37 976 A1 . Existing track position errors are reduced in proportion to the span widths of the measuring chords and the longitudinal distance of the measuring carriages. In the 4-point method, the existing relative track geometry is recorded by an additional measuring chord. A corresponding machine and method are described in the AT 520 795 A1 revealed.

In a compensation procedure with prior track measurement, the existing relative actual geometry of the track is measured with a preliminary run of the track tamping machine or a measuring car. For this purpose, a so-called inertial measurement unit (IMU) is used in modern track measuring vehicles. An inertial measurement system is described in the specialist journal Eisenbahningenieur (52) 9/2001 on pages 6-9. The DE 10 2008 062 143 B3 discloses an inertial measurement principle for recording a track position. Based on this measurement, a compensation calculation is carried out in which a previously unknown target geometry is calculated on the basis of the actual geometry.

As a rule, the actual geometry of the track is recorded in the form of a vertical and longitudinal height profile as well as a sequence of superelevation values. Based on this recording, a measuring unit calculates an electronic vertical height compensation, taking into account a previously defined speed class of the track as well as specified upper limits for displacement and lifting values. The measured vertical heights are smoothed in order to obtain a course that is as ideal as possible for the given conditions. The position of the transition points between the alignment elements (main track points) is determined during the compensation calculation.

In a next step, the resulting displacements and elevations are calculated from the verticals by applying a digital filter, by which the track must be corrected so that the calculated vertical progression can be achieved. The results of this further Calculations are therefore lifting and guide values (correction values) for the position correction of the track by means of the track tamping machine.

Repeated application of the compensation method has the disadvantage that the track main points drift away from their original positions (according to the originally defined design geometry). Thus, the aging of a track leads to an increasing deviation from the original design geometry despite corrections using the compensation method.

Minor changes in the position of the main track points are generally unproblematic. The route design often allows sufficient flexibility for determining the track position. However, difficulties arise at so-called constraint points or constraints such as bridges, tunnels or level crossings. There is no flexibility for relocating the track there. Therefore, according to the state of the art, it is common practice to set the displacement values at these points to zero when calculating the compensation.

The WO 2020/037343 A1 and EP 3 358 079 A1 also disclose methods for correcting and optimizing the track position.

representation of the invention

The invention is based on the object of improving a method of the type mentioned at the outset in such a way that correction values for a track position correction can be determined efficiently on the basis of measured values determined by an inertial measuring device. A further object of the invention is to specify a corresponding system.

According to the invention, these objects are achieved by a method according to claim 1 and a system according to claim 8. Dependent claims specify advantageous embodiments of the invention.

It is provided that a virtual inertial measurement of the same track section with a target geometry is calculated by means of a simulation device in order to obtain simulated measurement data for the target geometry, whereby correction values for correcting the position of the track are determined by means of a computing unit by subtracting the simulated measurement data from the measurement data of the inertial measuring device.

With the method according to the invention, correction values are determined directly on the basis of the measurement data of the inertial measuring device with sufficient accuracy. The measurement data of the inertial measuring device are form-accurate measurement data that directly reflect the track position errors. The simulated measurement data provide immediate comparison values for determining the correction data. The simulation according to the invention therefore leads to a significant simplification of the data processing process.

It is advantageous if the simulation facility is given the target geometry as a sequence of geometric alignment elements. For example, a known absolute track geometry (design geometry) is used. Main track points indicate a change in different alignment elements. Such alignment elements are in particular straight lines, circular arcs, transition curves and gradient breaks. To compare the actual geometry with the target geometry, for example, a fixed coordinate system with the starting point of a measurement run as the origin is selected. Of course, other coordinate systems can also be used for georeferencing.

In a further developed variant of the method, the measurement data of the inertial measuring device are filtered using a filter algorithm, whereby the simulated measurement data are filtered in the simulation device using the same filter algorithm. This is particularly useful for inertial measuring devices with integrated data filtering. In these cases, the output data of the measuring device is already available as filtered measurement data. Therefore, the simulated measurement data is also provided as filtered data in order to obtain correction values through a direct data comparison.

A further improvement is that the measurement data in the inertial measuring device are determined on the basis of a virtual regression line with a length between 100m and 300m, in particular with a length of 200m. This data determination allows the method to be used for high-speed lines because long-wave position errors are also reliably detected.

To improve data quality, it is useful to use the inertial measuring device to record measurement data along a measuring path at intervals of between 15 cm and 50 cm, particularly at intervals of 25 cm. This creates an accurate three-dimensional trajectory of the inertial measuring device moving along the track, and even very short-wave position errors are recorded.

For improved georeferencing, it is advantageous if measuring points on the track are recorded as location data using a GNSS receiver installed on the measuring vehicle and if the measurement data from the inertial measuring device are linked to the location data. In this way, location-related measurement data is recorded automatically. This location-related measurement data from the inertial measuring device can be compared with the simulated measurement data without further processing. Recording additional location data (for example using an odometer) is not necessary.

In a further development of the process, horizontal guide values and vertical lifting values of the track are derived from the determined correction values for position correction using the computing unit. These processed correction values can be used directly to control a lifting/straightening unit of a track construction machine in order to bring the track into a specified position.

The system according to the invention for carrying out one of the described methods comprises a measuring vehicle for driving on a track, with an inertial measuring device for detecting an actual geometry of a track section, wherein an evaluation device is set up to process measurement data from the inertial measuring device, wherein a simulation device is set up to simulate a virtual inertial measurement of the same track section on the basis of a target geometry and wherein a computing unit is set up to subtract the simulated measurement data from the measurement data from the inertial measuring device in order to determine correction values for correcting the position of the track. The system enables correction values to be determined directly at high measuring speeds. Measurement inaccuracies and distortions due to Pendulum or chord measurements are avoided. No transfer functions are required to compare the data recorded by the inertial measuring device with the target geometry. There is also no need to calculate trajectory coordinates because the simulated measurement data is subtracted from the original measurement data of the inertial measuring device.

The inertial measuring device includes a so-called inertial measurement unit (IMU), which is arranged on a measuring platform of the measuring vehicle. The exact position of the measuring platform in relation to the rails of the track is determined using non-contact position measuring devices. When using an inertial measuring unit, artifacts can occur in the measurement data, particularly when cornering. These artifacts result from specific characteristics of the inertial measurement method used. If the same inertial measurement method is now applied to the target geometry in virtual form, the same artifacts occur. The artifacts cancel each other out when the measurement data is subsequently subtracted to determine the correction values. This reduces the overall computing power required because the sometimes complex digital filtering of the measurement data is no longer necessary.

An improvement to the system is that the measuring vehicle includes a GNSS receiver for recording location data. In this way, the recorded measurement data can be automatically linked to GNSS data in order to carry out a location-related comparison with the simulated measurement data. Specifically, the GNSS receiver is used to determine the measuring points at which the measurement values are recorded in a geodetic reference system.

In an advantageous development of the system, a communication system is set up to transmit the correction data to a track construction machine, whereby a control device of the track construction machine is set up to process the correction values in order to bring the track into the specified target geometry by means of a controlled lifting/straightening unit. This system includes all components to record an actual geometry, correction values and to correct the track position. In this way, continuous maintenance of a track is possible.

Short description of the drawings

Fig. 1

Messfahrzeug auf einem Gleis

Fig. 2

Blockdiagramm zur Bestimmung von Korrekturwerten

Fig. 3

Diagramme eines Gleisverlaufs und ungefilterte Messdaten

Fig. 4

Diagramme eines Gleisverlaufs und gefilterte Messdaten

The invention is explained below by way of example with reference to the accompanying figures. They show in schematic representation:

Fig. 1

measuring vehicle on a track

Fig. 2

Block diagram for determining correction values

Fig. 3

Diagrams of a track course and unfiltered measurement data

Fig. 4

Diagrams of a track course and filtered measurement data

Description of the embodiments

Fig. 1 shows a measuring vehicle 1 with a vehicle frame 2 on which a car body 3 is built. The measuring vehicle 1 can be moved on a track 5 using rail bogies 4. For better illustration, the vehicle frame 2 including the car body 3 is shown lifted off the rail bogies 4. The vehicle 1 can also be designed as a track construction machine, in particular as a tamping machine. In this case, only one machine is required for measuring and correcting the track 5.

The rail bogies 4 are preferably designed as bogies. A measuring platform 6 is connected to the wheel axles of the bogie as a measuring frame, so that movements of the wheels are transmitted to the measuring frame 6 without spring action. In relation to the track 5, this results in only sideways or pendulum movements of the measuring frame 6. These movements are recorded by means of position measuring devices 7 arranged on the measuring frame 6. These are designed, for example, as laser line cutting sensors.

The position measuring devices 7 are components of an inertial measuring device 8 mounted on the measuring platform 6, which comprises an inertial measuring unit 9. The inertial measuring unit 9 is used to record measurement data of an actual geometry 10 of the track 5 during a measuring run. wherein relative movements of the inertial measuring unit 9 with respect to the track 5 are compensated by means of the data from the position measuring devices 7. Using the measurement results from the position measuring devices 7, the measurement data from the inertial measuring unit 9 can also be transformed to a respective rail 11 of the track 5. The result is an actual geometry 10 for each rail 11.

The measuring vehicle 1 also includes a GNSS receiver 12, with which the current position of the measuring vehicle 1 can be recorded. Due to the known position of the measuring vehicle 1 in relation to the track 5, the location coordinates of the track section currently being traveled can also be recorded. The track sections recorded correspond to a sequence of measuring points at which the inertial measuring device 8 collects measurement data.

For example, the GNSS receiving device 12 is rigidly connected to the vehicle frame 2 via a carrier 13. The GNSS receiving device 12 comprises several GNSS antennas 14 aligned with one another for precise detection of GNSS positions of the measuring vehicle 1. In order to detect pendulum movements of the vehicle frame 2 relative to the track 5, further position measuring devices 7 are arranged on the vehicle frame 2. Here too, laser line cutting sensors, for example, are used. For a simple embodiment of the invention, one GNSS antenna 14 is sufficient. In this way, actual positions on the track 5 or along a coaxial axis 15 are continuously recorded.

Alternatively or in addition, the location is recorded using an odometer, which can be used to determine a kilometerage along the measured track section. In any case, the result is location data that is linked to the measurement data from the inertial measuring device. This location reference can then be used to compare it with a known target geometry 16 of track 5.

For example, a fixed coordinate system is used to georeference the measurement results, which has its origin at the starting point of the measurement run. The X-axis points at the starting point in the direction of track 5 to be measured. The Y-axis is horizontally aligned across it. The Z-axis shows the elevation of track 5. During the During the measurement run, a path s is also recorded, which can be used in addition to a time stamp to synchronize measurement results from the different systems 8, 12. So-called main track points 17 are located along a measured track section. These main track points each mark a boundary between geometric alignment elements (e.g. straight line, transition curve, circular arc or full curve).

The block diagram in Fig. 2 illustrates an example diagram of the system components involved. The measurement data 18 recorded by the inertial measuring device 8 are fed to an evaluation device 19. A data integration algorithm is advantageously set up in the evaluation device 19, by means of which the measurement data 18 of the inertial measuring device 8 and GNSS data or location data 20 of the GNSS receiving device 12 and/or an odometer 21 are linked. It is important to ensure that all coordinates are related to a common coordinate system. A system processor is used to jointly evaluate the signals received by the GNSS antennas 19 and to compensate for the relative movements with respect to the track 5.

In a variant of the invention, the inertial measuring device 8 outputs unfiltered measurement data 18 of the inertial measuring unit 9, wherein relative movements of the measuring platform 6 with respect to the rails 11 are compensated. The location-related measurement data 22 provided by the evaluation device 19 are fed to a computing unit 23.

In addition to this recording of the actual geometry 10, the known target geometry 16 forms the starting point for the further process steps. The target geometry 16 is specified as the optimal virtual track course of a simulation device 24. The simulation device 24 is, for example, a separate computer that is set up to process virtual scenarios. To optimize the hardware, it can also be useful to combine the evaluation device 19, the computing unit 23 and the simulation device 24 in an integrated computer system.

A virtual inertial measuring device is set up in the simulation device 24, which has the same properties as the inertial measuring device 8 installed on the measuring platform 6. This virtual inertial measuring device is used to carry out a virtual measurement of the track course on the basis of the specified target geometry 16. The same track section is used for which the actual geometry 10 is also recorded. The real and virtual measuring devices use the same inertial measuring method. The result of the virtual measurement is simulated measurement data 25, which advantageously have a location reference in order to carry out a direct comparison with the real location-related measurement data 22.

In the computing unit 23, a location-related subtraction of the simulated measurement data 25 from the measurement data 18 of the real inertial measuring device 8 takes place. The result of this subtraction is correction values 26 for the track 5 in order to convert the recorded actual geometry 10 into the desired target geometry 16. It is advantageous if horizontal guide values and vertical lifting values of the track 5 are derived from the correction values 26 using the computing unit 23. For example, the correction values 26 are projected into an XY plane and in a Z direction of the underlying coordinate system. To specify a superelevation, each rail 11 is assigned its own lifting values.

The lifting and alignment values are then used to control a lifting/aligning unit of a known track construction machine, for example a track or universal tamping machine. A wireless communication system is advantageously set up to transmit the correction data 26 determined by the measuring vehicle 1 directly to the track construction machine. In another embodiment, the track construction machine also includes all the functions of the measuring vehicle 1 described here.

To correct the track position, track 5 is driven over using the track construction machine after preliminary measurements. According to the specified correction values 26, the track grid is brought into its desired position using the lifting/straightening unit and fixed there using a tamping unit. A chord measuring system is used to check the track position, which is based on the track construction machine is constructed. In an integrated machine 1, a so-called track geometry control computer (also called automatic control computer ALC) comprises the computing unit 23 and the evaluation device 19. The control computer serves as the central unit for determining the correction values 26 and for controlling the track construction machine.

Fig. 3 The top diagram shows a location map of a track section in a fixed coordinate system. The abscissa corresponds to the X coordinate and the ordinate corresponds to the Y coordinate. The track section shown begins with a straight line and then changes into a transition curve with increasing curvature until the curvature remains constant in a subsequent first circular arc (full arc). The track section then includes a transition curve with decreasing curvature, a second circular arc, another transition curve and a straight line.

The target geometry 16 of the track section specified for the simulation is shown with a thick continuous line. The individual routing elements border on each other at main track points 17. With an absolute location of the main track points 17, this optimal track position is also referred to as the design geometry of track 5. When specifying a relative target geometry 16, it may be advantageous to specify constraint points in order to determine the track position at level crossings, bridges, tunnels or similar constraints. A thin continuous line shows the actual geometry 10 recorded by the inertial measuring device 8.

Below the location image shown, a lateral position of a space curve recorded by the inertial measuring device 8 is shown. This is unfiltered measurement data 18, whereby the course corresponds approximately to a curvature diagram (curvature image). The path s is plotted on the abscissa. The ordinate shows the current amplitude a (curvature) over the path s. A known space curve algorithm is used for data acquisition. This also applies to the inertial measuring system from Applanix, which is described in the article mentioned at the beginning in the The method is described in the specialist journal Eisenbahningenieur (52) 9/2001 on pages 6-9. For example, a 200m long regression line is chosen to calculate an amplitude a at a current measuring point. A new calculation is carried out every 25cm along the track 5, so that an accurate and almost continuous course of the recorded measurement data 18 results.

The bottom diagram shows a lateral position of a spatial curve of the idealized, virtual track 5. The simulated measurement data 25 are plotted on the ordinate, which result from a measurement simulation with the virtual measuring device set up in the simulation device 24. This simulated measurement is also based on a regression line with a length of 200 m and a measurement interval of 25 cm. The virtual track measured in the simulation has the specified target geometry 16.

For the subsequent determination of the correction values 26, measurement data 18, 25 for the same track section are used. A local comparison is carried out either using a kilometerage or on the basis of GNSS data. The correction values 26 are then obtained directly by subtracting the two spatial curves shown.

In another variant, filtered measurement data from the inertial measuring device 8 are used ( Fig. 4 ). In the virtual measurement, the simulated measurement data 25 are filtered in the same way. For example, a FIR filter (Finite Impulse Response Filter) is used. Specifications can be found in the European standard EN 13848. According to this standard, error amplitudes in the wavelength range from 70m to 200m must also be assessed for routes with a maximum line speed of more than 250km/h. In the diagrams in Fig. 4 The measurement signal of the inertial measuring device 8 (thin line) and the simulated measurement signal (thick line) are filtered with a band-bass filter with a wavelength range of 3m to 70m.

Artifacts can occur in both real and virtual measurements due to the nature of the process. In the diagrams of the filtered measured values shown, such artefacts can be seen at the transitions between the alignment elements are visible. By subtracting the measurement data obtained from the actual geometry 10 and the target geometry 16, these artifacts are canceled out. The result is the correction values 26 for the corresponding track section. By directly subtracting the measurement data 18, 25, there is no need to determine 3D trajectories in the form of XYZ coordinates. Despite the required simulation, this results in a simpler and more accurate method for determining the correction values 26.

Claims (10)

1. A method for determining correction values (26) for correcting the position of a track (5), with an actual geometry (10) of a track section being recorded by means of an inertial measurement device (8) arranged on a track inspection vehicle (1) while the track (5) is being travelled on, and with measuring data (18) of the recorded track section being output by the inertial measurement device (5) to an evaluation device (19), characterised in that a virtual inertial measurement of the same track section with a target geometry (16) is calculated by means of a simulation device (24) in order to obtain simulated measuring data (25) for the target geometry (16), and that correction values (26) for correcting the position of the track (5) are determined by subtracting the simulated measuring data (25) from the measuring data (18) of the inertial measurement device (8) by means of a computing unit (23).
2. A method according to claim 1, characterised in that the target geometry (16) is given to the simulation device (24) as a sequence of geometric track alignment design elements.
3. A method according to claim 1 or 2, characterised in that the measuring data (18) of the inertial measurement device (8) are filtered by means of a filter algorithm and that the simulated measuring data (25) are filtered with the same filter algorithm in the simulation device (24).
4. A method according to one of the claims 1 to 3, characterised in that in the inertial measurement device (8), the measuring data (18) are determined on the basis of a virtual regression line with a length between 100m and 300m, in particular with a length of 200m.
5. A method according to one of the claims 1 to 4, characterised in that the inertial measurement device (8) records measuring data (18) along a measuring path (s) at distances between 15cm and 50cm, in particular at a respective distance of 25cm.
6. A method according to one of the claims 1 to 5, characterised in that measuring points on the track (5) are recorded as location data (20) by means of a GNSS receiving device (12) arranged on the track inspection vehicle (1) and if the measuring data (18) of the inertial measurement device (8) are linked to the location data (20).
7. A method according to one of the claims 1 to 6, characterised in that horizontal lining values and vertical lifting values of the track (5) are derived from the determined correction values (26) for correcting the position by means of the computing unit (23).
8. A system for carrying out the method according to one of the claims 1 to 7, with a track inspection vehicle (1) for travelling on a track (5), comprising an inertial measurement device (8) for recording an actual geometry (10) of a track section, with an evaluation device (19) being set up for processing measuring data (18) of the inertial measurement device (8), characterised in that a simulation device (24) is set up for simulating a virtual inertial measurement of the same track section on the basis of a target geometry (16), and that a computing unit (23) is set up for subtracting the simulated measuring data (25) from the measuring data (18) of the inertial measurement device (8) in order to determine correction values (26) for correcting the position of the track (5).
9. A system according to claim 8, characterised in that the track inspection vehicle (1) comprises a GNSS receiving device (12) for recording location data (20).
10. A system according to claim 8 or 9, characterised in that a communication system is adapted to transmit correction values (26) to a track maintenance machine, and that a control device of the track maintenance machine is adapted to process the correction values (26) in order to place the track (5) into the predefined target geometry (16) by means of a controlled lifting and lining unit.

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