METHOD AND SYSTEM FOR DETERMINING CORRECTION VALUES FOR CORRECTING THE POSITION OF A TRACK

Abstract

The invention relates to a method for determining correction values for correcting a position of a track, with an actual geometry of a track section being recorded by means of an inertial measurement device arranged on a track inspection vehicle while the track is being travelled on, and with measuring data the recorded track section being output by the inertial measurement device to an evaluation device. In this case, 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 measuring data for the target geometry, with correction values correcting the position of the track being determined by subtracting the simulated measuring data from the measuring data of the inertial measurement device by means of a computing unit. With the method according to the invention, correction values are determined directly on the basis of the measuring data of the inertial measurement device.

Claims

1. A method for determining correction values for correcting the position of a track, with an actual geometry of a track section being recorded by means of an inertial measurement device arranged on a track inspection vehicle while the track is being travelled on, and with measuring data of the recorded track section being output by the inertial measurement device to an evaluation device, wherein 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 measuring data for the target geometry, and that wherein correction values for correcting the position of the track are determined by subtracting the simulated measuring data from the measuring data of the inertial measurement device by means of a computing unit.

2. The method according to claim 1, wherein the target geometry is given to the simulation device as a sequence of geometric track alignment design elements.

3. The method according to claim 1, wherein the measuring data of the inertial measurement device are filtered by means of a filter algorithm and that wherein the simulated measuring data are filtered with the same filter algorithm in the simulation device.

4. The method according to claim 1, wherein in the inertial measurement device, the measuring data are determined on the basis of a virtual regression line with a length between 100 m and 300 m, in particular with a length of 200 m.

5. The method according to claim 1, wherein the inertial measurement device records measuring data along a measuring path (s) at distances between 15 cm and 50 cm, in particular at a respective distance of 25 cm.

6. The method according to claim 1, wherein measuring points on the track are recorded as location data by means of a GNSS receiving device arranged on the track inspection vehicle and if the measuring data of the inertial measurement device are linked to the location data.

7. The method according to claim 1, wherein horizontal lining values and vertical lifting values of the track are derived from the determined correction values for correcting the position by means of the computing unit.

8. A system for carrying out the method according to claim 1, with a track inspection vehicle for travelling on a track, comprising an inertial measurement device for recording an actual geometry of a track section, with an evaluation device being set up for processing measuring data of the inertial measurement device, wherein a simulation device is set up for simulating a virtual inertial measurement of the same track section on the basis of a target geometry, and wherein a computing unit is set up for subtracting the simulated measuring data from the measuring data of the inertial measurement device in order to determine correction values for correcting the position of the track.

9. The system according to claim 8, wherein the track inspection vehicle comprises a GNSS receiving device for recording location data.

10. The system according to claim 8, wherein a communication system is adapted to transmit correction values to a track maintenance machine, and wherein a control device of the track maintenance machine is adapted to process the correction values in order to place the track into the predefined target geometry by means of a controlled lifting and lining unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In the following, the invention is explained by way of example with reference to the accompanying figures. The following figures show in schematic illustrations:

[0028] FIG. 1 Track inspection vehicle on a track

[0029] FIG. 2 Block diagram for determining correction values

[0030] FIG. 3 Diagrams of a track course and unfiltered measuring data

[0031] FIG. 4 Diagrams of a track course and filtered measuring data

DESCRIPTION OF THE EMBODIMENTS

[0032] FIG. 1 shows a track inspection vehicle 1 with a vehicle frame 2 on which a vehicle body 3 is mounted. The track inspection vehicle 1 is movable on a track 5 by means of rail-based running gears 4. For better illustration, the vehicle frame 2 together with the vehicle body 3 is shown in a raised position from the rail-based running gears 4. The vehicle 1 can also be designed as a track maintenance machine, in particular as a tamping machine. In this case, only one machine is required to survey and to correct the track 5.

[0033] The rail-based running gears 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. Thus, there are only lateral or reciprocal movements of the measuring frame 6 in relation to the track 5. These movements are recorded by means of position measuring devices 7 arranged on the measuring frame 6. They are designed, for example, as laser light-section sensors.

[0034] The position measuring devices 7 are components of an inertial measurement device 8 mounted on the measuring platform 6, which comprises an inertial measurement unit 9. Measuring data of an actual geometry 10 of the track 5 are recorded by means of the inertial measurement unit 9 during a measuring run, with relative movements of the inertial measurement unit 9 in relation to the track 5 being compensated for by means of the data from the position measuring devices 7. By means of the measuring results of the position measuring devices 7, the measuring data of the inertial measurement 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.

[0035] The track inspection vehicle 1 further comprises a GNSS receiving device 12, by means of which a current position of the track inspection vehicle 1 can be recorded respectively. Due to the known position of the track inspection vehicle 1 in relation to the track 5, the position coordinates of the currently travelled track point can also be recorded. The recorded track points correspond to a sequence of measuring points at which the inertial measurement device 8 collects measuring data.

[0036] For example, the GNSS receiving device 12 is rigidly connected to the vehicle frame 2 via a carrier 13. Here, the GNSS receiving device 12 comprises several GNSS antennas 14 aligned towards each other for an accurate recording of GNSS positions of the track inspection vehicle 1. In order to record the reciprocal movements of the vehicle frame 2 in relation to the track 5, further position measuring devices 7 are arranged on the vehicle frame 2. Again in this case, laser light-section sensors are used. For a simple embodiment of the invention, one GNSS antenna 14 is sufficient. This way, actual positions on the track 5 or along a track centreline 15 are continuously recorded.

[0037] Alternatively or additionally, the location is recorded by means of an odometer, which can be used to determine a chainage along the measured track section. In any case, this results in location data which will be linked to the measuring data of the inertial measurement device. A comparison with a known target geometry 16 of the track 5 can be performed via this location reference.

[0038] For example, a stationary coordinate system is used for georeferencing the measuring results, the origin of which is at the starting point of the measuring run. At the starting point, the X-axis points in the direction of the track 5 to be measured. Crosswise to it, the Y-axis is horizontally aligned. The vertical position of the track 5 results on the Z-axis. During the measuring run, a distance s is further recorded which can be used, in addition to a time stamp, to synchronise the measuring results of the different systems 8, 12. Along a measured track section there are so-called track main points 17. These track main points each mark a boundary between geometric track alignment design elements (e.g. straight line, transition curve, circular curve, or full curve).

[0039] The block diagram in FIG. is an exemplary diagram illustrating the system components involved. The measuring data 18 recorded by the inertial measurement device 8 are fed to an evaluation device 19.

[0040] Advantageously, a data integration algorithm is set up in the evaluation device 19, by means of which the measuring data 18 of the inertial measurement device 8 as well as GNSS data, or location data 20 of the GNSS receiving device 12, and/or an odometer 21 are linked. It must be ensured 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 in relation to the track 5.

[0041] In one variant of the invention, the inertial measurement device 8 outputs unfiltered measuring data 18 from the inertial measurement unit 9; relative movements of the measuring platform 6 in relation to the rails 11 are compensated. The location-specific measuring data 22 provided by the evaluation device 19 are fed to a computing unit 23.

[0042] In addition to this recording of the actual geometry 10, the known target geometry 16 forms the starting point for the further steps of the method. In this case, 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 set up to process virtual scenarios. In order to optimise the hardware, it may also be useful to combine the evaluation device 19, the computing unit 23, and the simulation device 24 into an integrated computer system.

[0043] A virtual inertial measurement device is set up in the simulation device 24 which has the same characteristics as the inertial measurement device 8 set up on the measuring platform 6. By means of this virtual inertial measurement device, a virtual measurement of the track course is carried out on the basis of the predefined target geometry 16. For this, the track section is used for which the actual geometry 10 is recorded as well. The real and the virtual measurement device use the same inertial measurement method. The result of the virtual measurement are simulated measuring data 25, which, advantageously, have a location reference in order to perform a direct comparison with the real location-specific measuring data 22.

[0044] In the computing unit 23, a location-specific subtraction of the simulated measuring data 25 from the measuring data 18 of the real inertial measurement device 8 takes place. The result of this subtraction are correction values 26 for the track 5 that are used to transform the recorded actual geometry 10 into the desired target geometry 16. In this context, it is advantageous if horizontal lining values and vertical lifting values of the track 5 are derived from the correction values 26 by means of the computing unit 23. For example, the correction values 26 are projected in an XY plane and in a Z direction of the underlying coordinate system. For determining of a superelevation, each rail 11 is assigned its own lifting values.

[0045] Subsequently, the lifting and lining values are used to actuate a lifting and lining unit of a track maintenance machine known per se, for example a plain-line or universal tamping machine. Advantageously, a wireless communication system is set up to transmit the correction data 26 determined by means of the track inspection vehicle 1 directly to the track maintenance machine. In another embodiment, the track maintenance machine also comprises all functions of the track inspection vehicle 1 described herein.

[0046] For correcting the track position, the track 5 is travelled on by the track maintenance machine after pre-measurement. According to the preset correction values 26, the track panel is placed in its desired position by means of the lifting and lining unit and is fixed in place by means of a tamping unit. A chord measuring system mounted on the track maintenance machine is used to check the track position. In an integrated machine 1, a so-called track geometry guiding computer (also called ALC, automatic guiding computer) comprises the computing unit 23 and the evaluation device 19. The guiding computer serves as the central unit for determining the correction values 26 and for controlling the track maintenance machine.

[0047] In FIG. 3, the top diagram shows a location diagram of a track section in a stationary 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 the subsequent first circular curve (full curve). Subsequently, the track section comprises a transition curve with decreasing curvature, a second circular curve, a further transition curve, and a straight line.

[0048] The target geometry 16 of the track section predefined for the simulation is shown with a thick continuous line. The individual track alignment design elements are adjacent to each other at track main points 17. With an absolute localisation of the track main points 17, this optimal track position is also referred to as design geometry of the track 5. When specifying a relative target geometry 16, it may be advantageous to define points of restraint in order to determine the track position at level crossings, bridges, tunnels, or similar constraining means. A thin continuous line shows the actual geometry 10 recorded by means of the inertial measurement device 8.

[0049] A lateral position of a space curve recorded by mea ns of the inertial measurement device 8 is shown under the depicted location diagram. This is unfiltered measuring data 18, making the course correspond approximately to a curvature diagram (curvature illustration). The distance s is plotted on the abscissa. The ordinate shows the current amplitude a (curvature) above the distance s. A space curve algorithm known per se is used for data recording. This also applies to the inertial measurement system of the company Applanix, which is described in the article mentioned above in the technical journal Eisenbahningenieur (52) 9/2001 on pages 6-9. For example, a 200 m long regression line is chosen in order to calculate an amplitude a at a current measuring point. In the process, a recalculation is carried out along the track 5 every 25 cm, resulting in an exact and almost continuous course of the recorded measuring data 18.

[0050] The lowest diagram shows a lateral position of a space curve of the idealised, virtual track 5. In this, the simulated measuring data 25 resulting from a measurement simulation with the virtual measuring device set up in the simulation device 24 are plotted on the ordinate. A regression line with a length of 200 m and a measurement interval of 25 cm is equally used for this simulated measurement. The virtual track measured in the simulation has the predefined target geometry 16.

[0051] For the subsequent determination of the correction values 26, measuring data 18, 25 are used for the same track section. A local comparison is made either on the basis of a chainage or on the basis of GNSS data. The correction values 26 then result directly from a subtraction of the two space curves shown.

[0052] In another variant, filtered measuring data from the inertial measurement device 8 are used (FIG. 4). With the virtual measurement, the simulated measuring data 25 are filtered in the same way. For example, an FIR filter (finite impulse response filter) is used. Specifications can be found in the European Standard EN 13848. According to this Standard, fault amplitudes in the wavelength range from 70 m to 200 m must also be assessed for lines with a maximum line speed of more than 250 km/h. In the diagrams in FIG. 4, the measuring signal of the inertial measurement device 8 (thin line) and the simulated measuring signal (thick line) are filtered using a band-pass filter with a wavelength range of 3 m to 70 m.

[0053] Method-related artefacts can occur in both the real and in the virtual measurement. In the diagrams of the filtered measuring values shown, such artefacts are visible at the transitions between the track alignment design elements. By subtracting the obtained measuring data of the actual geometry 10 and the target geometry 16, these artefacts cancel each other out. As a result, the correction values 26 for the corresponding track section are obtained. By directly subtracting the measuring data 18, there is no need to determine 3D trajectories in the form of XYZ coordinates. This results in a simpler and more accurate method overall for determining the correction values 26, despite the necessary simulation.