EP0689983A1 - Method for detecting the position of a predetermined axle of a railway vehicle on a rail section - Google Patents

Abstract

A method for ascertaining the position (POS) of an assigned axle (A4) of rail-borne vehicle (F) on a railway section (GA) involves obtaining a position signal for the axle on the railway section (GA) in order to derive a position result from the position signal by assigning reference values. In order to provide an exact location of the axle and rail-borne vehicle on a limited section of railway, an annunciation signal (Ut) is generated when the axle (A4) passes a defined fixed point on the railway section (GA), followed by checking for any deviation of the obtained position signal (fs) for this point.

Description

The invention relates to a method for determining the position of a specific axis of a rail vehicle on a track section, in which a position signal dependent on the position of the axis in the track section is obtained, from which a position information is derived by assigning reference values.

EP-B1-0 272 343 discloses a method and a device for monitoring the presence of rail vehicles within a track section, the track section being divided into many comparatively short subsections, at the end of which a transmitter / receiver module is arranged. A receiver designed as a digital track level meter at the beginning of the track section cyclically checks which modules can be used to determine a response signal upon request. The known method thus allows only a digital (free / busy) check of the subsections. The position of an axle of a vehicle within the subsection can therefore not be resolved more precisely. In order to achieve a sufficient resolution, a very fine division and therefore a high number of transmitter / receiver modules is required.

German patent 967 440 relates to a device for indicating the filling status of a track, the track forming a conductor loop, the electrical resistance of which is determined by the short-circuit-generating position of the last vehicle axle in the direction of entry. According to the additional patent 11 19 901 granted for this purpose, one that already occurs when the track is free due to the conductance of the track bed or a permanent conductive connection between the rails Deflection of a level indicator is compensated by a counter voltage.

EP-A2-0 539 046 describes a track section that is equipped at both ends with a transmitter and a receiver for bidirectional signal transmission over the tracks for the position detection of a vehicle. A vehicle position is also detected here by means of a current or voltage measurement.

The essay "THE INSULATION-FREE TONE FREQUENCY-GLEISSTROMKREIS DER BAUART WSSB" by V. Bechstein in DEUTSCHE EISENBAHNTECHNIK, Jg. 13, 2/1965, pages 83 ff. Describes a track section with a receiver, which results from the short-circuit effect in a track circuit without an insulation shock a busy message is generated.

From DE-C2-31 27 672 a method of the type mentioned is known, the track section being isolated from other adjacent track sections of an entire track by separating joints and being designed as a track circuit. An oscillator is connected to the track circuit, the rest frequency of which varies depending on the inductance of the track circuit - which in turn changes with the position of the axis. The frequency determined thus represents a position-dependent position signal which exhibits marked frequency jumps when an axis enters or leaves the track section. The position signal is forwarded to a converter designed as a memory, which contains for each possible frequency a value for the free length of the associated track circuit or track section, determined in each case by tests or by calculation. By assigning the corresponding value to the determined position signal, a position specification is obtained which is functionally related to the location of the respective axis.

In this known method, position signals determined for the same location can e.g. B. drift due to external influences (weather; insulation resistance between the rails; track structure), so that after the assignment of the previously determined reference values increasingly inaccurate position information results.

The invention is therefore based on the object of providing a method for determining the position of a specific axis of a rail vehicle on a limited track section, which enables the axis and thus the rail vehicle to be precisely located even in the event of a longer operating time and in the event of external interference.

This object is achieved according to the invention in a method of the type mentioned at the outset in that a signal is generated when the axis passes a defined fixed point on the track section, and it is checked whether a deviation of the position signal obtained for this point or the derived position specification from one there is a target value applicable for this point, and that, if necessary, the deviation of the position signal is reduced or the assignment of the reference values to the position signal is corrected. An essential aspect of the invention consists in that, in addition to the reference values for the limits of the track section (first and second support points) that can be used to compare the functional relationship between the position of the axis and the position signal, with the signaling signal, a third support point, which is independent of the position signal, as a setpoint is available for assessment and, if necessary, for comparing the functional relationship or for correcting the assignment. Each crossing of the defined fixed point advantageously provides a current, reliable setpoint for the position signal or the position indication, so that two are determined using essentially independent methods Comparable information is available. The position signal for this point can either be present as a separate measured value or can be obtained by a suitable interpolation of the position signals in the area of the fixed point.

At the start of operation, the method according to the invention not only generates digital information (free / occupied) for the track section, but already allows the axis position to be estimated via the position signal. A substantial increase or check of the accuracy of the position signal can be achieved relatively quickly during normal operation of the track section. This is particularly advantageous if, for example, the determined position signals and thus the position information obtained deviate significantly from the target values corresponding to the actual position of the fixed point due to longer breaks in operation. The functional relationship can be corrected using known mathematical methods (for example regression analyzes); From the deviation found, interpolation can be used to correct the position signals or the assignment by adaptive control or tracking.

A particularly advantageous embodiment of the invention provides that the fixed point is provided in the central area of the track section.

In order to limit the influence of particularly high deviations (statistical outliers), a further preferred embodiment of the invention provides that the tracking is only carried out if significant deviations from the target value that are in the same direction are found several times.

According to an advantageous development of the invention, the signal can be generated by a wheel sensor. The signal can also be generated by a switch that When passing the axis, the rails short-circuit in a defined manner and thus cause a significant jump in the position signal curve (for example a frequency jump in the inductive method described at the beginning).

In the case of multi-axle vehicles in particular, it is advantageous if the point in time at which the last axle of the vehicle passes the fixed point is determined, so that the position signal and the signaling signal for the last axle can be evaluated.

For this purpose and with a view to simplified data processing, at least the last two position signals at the times of the last two signal signals can remain stored.

A further advantageous embodiment of the method according to the invention provides that the deviation of the position signal or the position specification from the target value in the vicinity of the fixed point is determined with the aid of a suitable smoothing function. For example, a regression line can be used for this; In order to form the regression line, a predetermined number of position signals or details can be stored continuously for a certain period of time (for example 20 s). Knowing the point in time of the signal, a value for the position signal or the position indication, from which the deviation is determined, can be determined by averaging a value that is free from random interference or noise.

• Figur 1 eine schematische Darstellung der Positionsermittlung einer Achse auf einem Gleisabschnitt,
• Figur 2 in Abhängigkeit von der Achsposition ermittelte Positionssignale und
• Figur 3 eine markante Sprünge aufweisende Frequenzkurve.

The invention is explained further below by way of example with reference to a drawing; show it:

• FIG. 1 shows a schematic representation of the position determination of an axis on a track section,
• Figure 2 as a function of the axis position determined position signals and
• FIG. 3 shows a frequency curve with striking jumps.

According to FIG. 1, in the method according to the invention for determining the position POS of a specific axis A4 of a rail vehicle F (not shown in more detail), a limited track section GA is integrated into the resonant circuit of an oscillator OS in a manner known per se (DE-C2-31 27 672). The oscillator OS is electrically isolated from the track section GA via a transformer TR. The track section GA is electrically insulated from adjacent track sections by dividing joints T1, T2. The axes A1 to A4 of the vehicle F short-circuit the two rails S1, S2 of the track section GA - as a result of which the track circuit inductance changes as a function of the axis position - and thus influence the oscillation frequency f (s) of the oscillator OS. Since the oscillator OS is coupled (seen in the direction of travel R) to the start region of the track section, the position of the last axis A4 is essentially decisive for the change in impedance of the track section and thus for the change in the oscillator frequency. The frequency determined as the position signal f (s) is a function of the path s between the start A of the track section GA and the axis position POS, with a basic relationship of the shape

Accordingly, a position specification PA (s) for the location of the axis A4 can be determined from the position signal f (s) by calculating or assigning previously stored reference values (as described at the beginning). When the vehicle F rolls into the track section GA, the frequency jumps from a rest value of, for example, 4 kHz (FIG. 2) to a value of z. B. 10 kHz and decreases with the further movement of the axis A4 along the path S hyperbolic function to a final value of, for example, 7 kHz. If the axis A4 the track section GA leaves (open track circuit), frequency f jumps back to the idle value.

The position signal f (s) obtained can deviate from the position signal (setpoint) originally determined for the respective location due to externally caused changes (e.g. change in the bedding resistance, electrolyte formation due to lost cargo) of the track section-specific inductance.

The frequencies actually measured then no longer correspond to the frequency values originally determined for the respective positions, as are shown in the solid curve K1 according to FIG. 2. Rather, the position signal can correspond to the frequency curve of the dashed curve K2 or the dash-dotted curve K3, wherein the curves K1 to K3 can differ from one another in their initial and final values and also in their curvatures.

während einer Vertrauenszeit T_ver - spätestens jedoch nach Verlassen des Gleisabschnittes - kein weiteres Meldesignal eingeht, kann mit hinreichender Sicherheit davon ausgegangen werden, daß die letzte Achse A4 den Punkt P passiert hat. Das erfindungsgemäße Verfahren kann sich dazu eines Beobachtungsfensters der Länge s_er bedienen, da die Lage des Punktes P vorab bekannt ist und damit auch der Kurvenabschnitt vorherbestimmbar ist, in dem dem Punkt P zugeordnete Positionssignale zu erwarten sind.As FIG. 1 further shows, a wheel sensor RS is arranged at a defined, fixed point P of the track section GA, which then generates a signal U (t) when the point P is passed by an axis A1 to A4. As Figure 2 shows, thus arise at defined times t₁ to t₄ diracimpulse-like signaling signals U1 to U4, each indicating the passage of point P from one of the axes A1 to A4. Positions t₁ to s₄ can be assigned to the times t₁ to t₄ (linear at constant speed, otherwise by evaluating the speed curve). Depending on the desired representation, the time t or the location s is therefore plotted on the abscissa. At each of the times t1 to t4, preferably at least at the last times t3, t4, the position signals f (s, t₃) obtained at this time are; f (s, t₄) stored in a memory SP. If after the last signal ${\text{U}}_{\text{4th}}{\text{= U (t}}_{\text{4th}}\text{)}$

_ver during a time T confidence - at the latest after leaving the Track section - no further signal is received, it can be assumed with sufficient certainty that the last axis A4 has passed point P. For this purpose, the method according to the invention can use an observation window of length s _er , since the position of point P is known in advance and thus the curve section in which position signals assigned to point P are to be expected can also be predetermined.

) des Gleisabschnitts gewonnen wurden, für sämtliche Frequenzwerte f(s) eine Nachführung (im vorliegenden Beispiel Anhebung) und ggf. Korrektur der Krümmung vorgenommen, so daß annähernd die Frequenzkurve K1 erreicht und damit der ursprüngliche funktionale Zusammenhang wiederhergestellt wird. Der Abgleich kann alternativ auch dadurch erfolgen, daß die Zuordnung der Referenzwerte zu den Positionssignalen entsprechend angepaßt wird.The at time t₄ obtained and stored position signal f (s, t₄) may now be compared on the temporal association with the data obtained through the notification signal target value of the ideal or nominal curve K1 for the frequency f (s _p) at point P (point of intersection SP1) become. The signal U₄ allows namely to check whether the assigned position signal f (t₄) actually lies on the target curve K1 previously used for determining the position or on a deviating curve K3 (intersection point SP2). If the position signal f (t₄) lies outside a predeterminable tolerance band TB, interpolative methods may be used with the aid of the frequency values that are used for the start A (f (s = 0)) and for the end E ( ${\text{f (s = s}}_{\text{Max}}\text{)}$

) of the track section were obtained, for all frequency values f (s), a tracking (in the present example, raising) and, if necessary, correction of the curvature, so that the frequency curve K1 is approximately reached and the original functional relationship is thus restored. Alternatively, the adjustment can also be carried out by adapting the assignment of the reference values to the position signals accordingly.

In order to eliminate extreme values (outliers) of the position signal, the above-described correction is preferably only carried out when the position signals deviate in the same direction several times in succession in each case.

FIG. 3 shows another transmission and generation option for the signal signals M1 to M4, in that when the point P (FIG. 1) passes the axes A1 to A4, a defined short circuit is generated between the rails S1, S2. This short circuit leads to striking jumps (signal signals M (t)) in the frequency curve shown in FIG. 3. On the basis of these jumps, the times t₁ to t₄ can be determined in a corresponding manner for the purposes described above. An advantage of this embodiment is that the signal signals M₁ to M₄ the position signal superimposed on the rails S1 and S2 can be passed.

In principle, the resistance measurement of the track section known for example from DE-PS 967 440 or DE-PS 11 19 901 can also be used to generate the position signal.

With the method according to the invention, two support points for the beginning and the end of the track section and a further independent support point preferably assigned to the central area of the track section are generated via two different measurement methods or media. An extremely precise adaptation of the curve shape or the assignment of the reference values to the position signals is thus possible, so that an extremely exact location of an axle of a rail vehicle is possible. The method according to the invention can be used particularly advantageously for locating in directional tracks. The message signals supplied during normal operation mean that adaptive control or tracking to the actual conditions can be implemented without interrupting operation. The very precise location determination that can be achieved with the method according to the invention and stable over time allows the running speed to be determined by differentiation and thus a determination of the running speed or a prognosis of the running distance to to a standstill of the vehicle. As a result, the method according to the invention can be used advantageously, in particular for braking the running target on directional tracks at marshalling yards.

Claims (8)

Method for determining the position (POS) of a specific axis (A4) of a rail vehicle (F) on a track section (GA),
in which a position signal (f (s)) dependent on the position (POS) of the axis (A4) on the track section (GA) is obtained, from which a position indication (PA (s)) is derived by assigning reference values,
characterized,
that a signal (U (t)) is generated when the axis (A4) passes a defined fixed point (P) of the track section (GA),
it is checked whether there is a deviation of the position signal (f (s)) obtained for this point or the derived position specification (PA (s)) from a setpoint value (f (s _p )) applicable for this point, and
that, if necessary, the deviation of the position signal (f (s)) is reduced or the assignment of the reference values to the position signal (f (s)) is corrected. Method according to claim 1,
characterized in that
the fixed point (P) is provided in the central area of the track section (GA). The method of claim 1 or 2,
characterized in that
the tracking or correction is only carried out when significant deviations of the position signal (f (s)) or the position specification (PA (s)) from the setpoint (f (s _p )) are detected. Method according to one of the preceding claims,
characterized in that
the signal (U (E)) is generated by a wheel sensor (RS). Method according to one of claims 1 to 3,
characterized in that
the signal (U (t)) is generated by a switch that short-circuits the rails (S1, S2) when it passes the axis (A4). Method according to one of the preceding claims,
characterized in that
it is determined when the last axis (A4) of the vehicle (F) passes the fixed point (P). Method according to one of claims 1 to 6,
characterized in that
at least the last two position signals (f (s, t₄); f (s, t₃)) at the times (t₄, t₃) of the last two signals (U (t₄); U (t₃)) are stored. Method according to one of the preceding claims,
characterized in that
the deviation of the position signal (f (s)) or the position specification (PA (s)) from the target value (f (s _p )) in the vicinity of the fixed point (P) is determined with the aid of a suitable smoothing function.

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