Method And Device For Determining Absolute Speed Of A Rail Vehicle

Abstract

A method for determining absolute speed of a rail vehicle including onboard sensor devices and a signal processor, wherein the method includes the steps of detecting irregularities in the rail respectively on one front wheel set via a first sensor device and at least on a subsequent wheel set via another sensor device, and transmitting the sensor signals produced by the sensor devices to a signal processor configured to determine the absolute speed by analyzing the supplied sensor signals, where an estimation of the transfer function between a sensor is used, and where an FIR filter can, in this case, optimally reproduce the signal of one sensor via the signal of the other sensor in which the smallest square of the error is formed such that the time offset between both signals can be determined, from which the speed can be determined at a known distance of the sensor.

Claims

1.-16. (canceled)

17. A method for determining an absolute speed of a rail vehicle, sensor devices and a signal processing device being provided on board, the method comprising: a) detecting an unevennesses of a rail at a leading wheelset of the rail vehicle via a first sensor device and at least at a following wheelset via a further sensor device; and b) transmitting sensor signals generated by the first and further sensor devices to a signal processor which is configured to determine, via analysis of the transmitted sensor signals supplied to the signal processor, an absolute speed, a temporal position of a value maximum in filter coefficients of an estimated transfer functions between the transmitted sensor signals being utilized during said analysis.

18. The method as claimed in claim 17, wherein the first and further sensor devices are configured to detect one of (i) a displacement, (ii) a speed, (iii) an acceleration in a z (vertical) direction (iv) a y (lateral) direction and (v) a respective differential or integral of the first and further sensor devices.

19. The method as claimed in claim 17, wherein at least two sensor devices are respectively arranged on successive axleboxes of different wheelsets.

20. The method as claimed in claim 18, wherein at least two sensor devices are respectively arranged on successive axleboxes of different wheelsets.

21. The method as claimed in claim 17, wherein a sensor device is configured to detect unevennesses of one of (i) one and another rail and (ii) over both rails simultaneously via axlebox sensors.

22. The method as claimed in claim 18, wherein a sensor device is configured to detect unevennesses of one of (i) one and another rail and (ii) over both rails simultaneously via axlebox sensors.

23. The method as claimed in claim 18, wherein the first and further sensor devices are each arranged over an associated primary spring.

24. The method as claimed in claim 18, wherein the first and further sensor devices are arranged on a plurality of wheel trucks traveling one behind another; and wherein sensor signals of leading wheelsets and following wheelsets are utilized to determine the absolute speed of the rail vehicle.

25. The method as claimed in claim 17, wherein the first and further sensor devices are arranged on a plurality of wheel trucks of a rail vehicle; and wherein a combination of a plurality of wheel truck pairs is utilized to determine the absolute speed of the rail vehicle.

26. The method as claimed in claim 17, wherein the signal processing device is a digital computer system which calculates the transfer functions via adaptive filters from the transmitted sensor signals supplied sensor signals and which, from a temporal position of a maximum in a shape of the filter coefficients, determines the absolute speed.

27. The method as claimed in claim 26, wherein the signal processing device takes into account sensor signals of a plurality of sensor pairs during determination of the transfer functions.

28. A device for determining the absolute speed of a rail vehicle, comprising: a) a first sensor device associated with a leading wheelset of the rail vehicle; b) at least one further sensor device with a following wheelset of the rail vehicle, the first and further sensors being configured to detect unevennesses of a rail; c) a signal processor to which sensor signals of individual sensor devices are supplied, the signal processor being configured to perform an analysis of the sensor signals and to determine the absolute speed of the rail vehicle from the supplied sensor signals; wherein a temporal position of a value maximum in filter coefficients of the estimated transfer functions between the sensor signals is utilized during the analysis.

29. The device as claimed in claim 28, wherein the first and further sensor devices are configured to detect one of (i) a displacement, (ii) a speed, (iii) an acceleration in a z (vertical) direction (iv) a y (lateral) direction and (v) a respective differential or integral of the first and further sensor devices.

30. The device as claimed in claim 28, wherein the first and further sensor devices are each formed by axlebox sensors which are arranged on different wheelsets.

31. The device as claimed in claim 28, wherein at least two sensor devices are respectively arranged on successive axleboxes of different wheelset.

32. The device as claimed in claim 28, wherein the rail vehicle comprises a plurality of wheel trucks, the first and further sensor devices being arranged on a plurality of said wheel trucks and each sensor signal being supplied to the signal processing device.

33. The device as claimed in claim 28, wherein the signal processing device is a digital computer system which calculates, via adaptive filters, from the supplied sensor signals, the transfer functions and determines the absolute speed of the rail vehicle from the transfer functions.

34. The device as claimed in claim 33, wherein the signal processing device take into account sensor signals of a plurality of sensor pairs to determine the transfer functions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] For further explanation of the invention, reference will be made in the following section of the description to the drawings which illustrate further advantageous embodiments, details and developments of the invention, using non-limiting exemplary embodiments, in which.

[0026] FIG. 1 is a schematic representation of a wheel truck with a leading and following wheelset, seen from the side, where in the exemplary embodiment shown, the sensor devices are arranged on the axleboxes in accordance with the invention;

[0027] FIG. 2 is a graphical plot of a first excitation signal as a function of time, measured at the leading wheelset of FIG. 1;

[0028] FIG. 3 is a graphical plot of a second excitation signal as a function of time, measured at the following wheelset of FIG. 1;

[0029] FIG. 4 is an exemplary embodiment of the invention, where the sensor device is arranged on the wheel truck frame on a wheel truck above the primary springs of the axleboxes of the wheelsets;

[0030] FIG. 5 is a further exemplary embodiment of the invention, where the measuring position is placed in the wagon body, in each case, above the wheel truck center, and where a plurality of such measuring devices are taken into account for the determination of the absolute speed; and

[0031] FIG. 6 is a flowchart of the method in accordance with the invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0032] FIG. 1 shows, in a simplified representation, a wheel truck 2 of a rail vehicle (not shown in detail). Wheels 9, 10 are arranged in pairs on a wheelset 16 positioned in front in the direction of travel and on a following wheelset 17. The wheelsets have an axle spacing a from one another. As shown in exaggerated form in FIG. 1, the running surface of the rail 1 is uneven. In the view shown in FIG. 1, the direction of travel is from right to left. If, therefore, the front wheel 9 travels over an unevenness, the following wheel follows it in a temporally offset manner. The unevennesses causes vibration excitations that are evaluated by measuring technology. As FIG. 1 indicates, a sensor device is associated with each axlebox: the sensor device 11 with the front axle, the sensor device 12 with the rear axle. These sensor devices 11, 12 can represent different physical parameters according to embodiment, depending on direction, for example: displacement, speed, acceleration or variables derived therefrom, such as their differential or integral. In relation to the track section, the z-direction should be understood as a vertical direction, whilst the y-direction denotes a lateral direction. Each sensor device generates a respective sensor signal 18 that is supplied to a signal processor and evaluation device 14. The evaluation device essentially consists of a processor system suitable for railroad use. An algorithm able to run on this processor system determines the similarity of the two temporally sequential sensor signals 18. In the present example, this is an algorithm for calculating the transfer function (UTF) via an adaptive filter, where the calculation can occur both in the time domain and also in the frequency domain. An FIR filter reproduces the signal of one sensor as well as possible via the signal of another sensor in that the least error sum is formed. The comparison result is the temporal delay t being sought (see FIGS. 2 and 3).

[0033] FIGS. 2 and 3 show, by way of example, graphical plots of the measurement signals arising from unevennesses of the rail as a function of time: the excitation signal 6 at the front wheel 3 (signal pattern sa1(t) in FIG. 2) and the excitation signal 7 at the rear wheel 4 (signal pattern sa1(t) in FIG. 3). Both signals 6, 7 are similar in their temporal sequence, essentially displaced by a time interval t. If this temporal delay t is known after the evaluation of the similarity, then taking the known spacing a between the axles 3, 4 of the wheels 9, 10, the actual speed of the rail vehicle can very easily be determined by evaluating the relation v=a/t (where v is absolute speed; a is axle spacing; t is the delay).

[0034] FIG. 4 shows an embodiment of the invention in which, on a wheel truck 2, the sensors 11, 12 are placed over the primary spring stage 15. The principle is as described above. The excitation signals (in FIGS. 2 and 3, the signal patterns sa1(t) and sa2(t)) determined by the two sensors 11, 12 are each fed as a signal 18 to the signal detecting and evaluating device 14, which then determines the delay t and calculates the actual speed of the rail vehicle using the relation given above.

[0035] FIG. 5 shows another exemplary embodiment of the invention. Here, the two sensor devices 11 and 12 are each arranged in a wagon body 13, where each of these wagon bodies 13 is situated on a front wheel truck 2 and a rear wheel truck 2. Further wheel trucks can be arranged in the railroad train between these two wheel trucks 2, 2. Each of the signals 18 generated by the measuring devices 11 and 12 is passed on to a signal capture and evaluating unit 14. This unit determines the delay t between the signals 6, 7 using the aforementioned algorithm for signal analysis. As distinct from the representation in FIGS. 1 and 4, in the present example, the spacing A between the two wheel trucks 2, 2 is used for the determination of the absolute speed v.

[0036] FIG. 6 is a flowchart of a method for determining an absolute speed of a rail vehicle, where sensor devices (11, 12) and a signal processing device (14) being provided on board the rail vehicle. The method comprises detecting an unevennesses of a rail (1) at a leading wheelset (16) of the rail vehicle via a first sensor device (11) and at least at a following wheelset via a further sensor device (12), as indicated in step 610. Sensor signals (18) generated by the first and further sensor devices (11, 12) are now transmitted to a signal processor (14) which is configured to determine, via analysis of the transmitted sensor signals (18) supplied to the signal processor (14), an absolute speed, as indicated in step 620. In accordance with the invention, the temporal position of a value maximum in the filter coefficients of an estimated transfer functions (UTF) between the transmitted sensor signals is used during the analysis.

[0037] While there have been shown, described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the methods described and the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.