Method for determining at least one geometric parameter of railway track and system for carrying out method

Abstract

A method of determining at least one geometric parameter of a railway track (1) comprises the steps of providing a vehicle (10) carrying an inertial unit (34), a set of devices (28) for measuring at least one relative orientation component of at least a plurality of rows of rails with respect to the inertial unit, and one or more odometers (26) traveling along the railway track (1), a continuous value of at least one absolute positioning or orientation component of the row of observed guide rails (2) is calculated from the signals generated by the odometer (26), the set of measuring devices (28) and the inertial unit (34), and a function s-G (s) is constructed, the function correlates continuous curve abscissa values with adjoining values from continuous values of absolute positioning or orientation components of the row of rails observed in the spatial region, applying a high-pass linear filter or a band-pass linear filter to the function s-G (s) to construct a filtering function s-F (s), and then calculating an integral value [mathematical formula 14].

Description

Technical Field

[0001] The invention relates to the determination of certain parameters of the geometry of a railway track, in particular with a view to checking or controlling it, for example during laying, monitoring, maintenance or renovation. Background Art

[0002] The main geometrical parameters of the track defined in the EN 13848 standard are:

[0003] Specifications: Minimum distance between rails up to 14 mm below the running surface;

[0004] Longitudinal level: The change in height of a continuously running surface relative to a reference height which is a sliding average;

[0005] Inclination: The height difference between the running surfaces of the left and right rails;

[0006] Alignment: the change in position in the horizontal plane of the position of each row of rails relative to a reference position taken as a sliding average;

[0007] Twist: A change in tilt.

[0008] The measurements of longitudinal level, alignment and twist are measurements of variation. They are relative measurements, as opposed to absolute measurements such as tilt and gauge. According to the standard, longitudinal level and alignment are studied at different wavelength ranges:

[0009] D1: 3m to 25m

[0010] D2: 25m to 70m

[0011] D3: 70m to 150m

[0012] In order to determine the geometry of railway tracks, it is known to run an instrumented vehicle on the track, the body or bogie chassis of which is equipped with an inertial unit providing gyroscopic measurements of yaw, pitch and roll angles and acceleration measurements along three axes. The vehicle is also equipped with a detection laser to determine the relative position of the chassis and therefore the relative position of the inertial unit with respect to the row of railway tracks.

[0013] This non-contact inertial measurement unit is used in the IRIS 320 (TGV d'Inspection Rapide des Installations de Sécurité à 320 km / h) high-speed measurement train, which measures all track geometry parameters at speeds of up to 360 km / h.

[0014] A disadvantage of this system is that it sets a minimum speed for the measuring vehicle on the track. At low speeds, the acceleration signal that provides access to all three-dimensional displacements in space through double time integration is weak and does not utilize the full dynamic range of the sensor. Therefore, the acceleration measurements are potentially subject to systematic inaccuracies or biases amplified by the double integration operation, producing points of constant time drift when estimating all three-dimensional displacements. In practice, it should be noted that these drifts are no longer negligible below a certain traffic speed (which can actually be 60 km / h), making it impossible to obtain measurements for slow runs or for runs with stops. Therefore, the application areas of measuring vehicles equipped with such traditional inertial measurement systems are limited. In particular, they cannot be used at track renovation sites, because the working speeds at track renovation sites are much lower than the minimum operating speed of the measuring device and the speed at the track renovation site may be zero during stops of arbitrarily long duration. Summary of the invention

[0015] The object of the present invention is to remedy the disadvantages of the prior art and to provide a device for determining the geometry of a railway track with a practically desirable accuracy, which is achievable at low track speeds (including during arbitrarily long stops).

[0016] According to a first aspect of the invention, a method for determining at least one geometrical parameter of a railway track having two rows of guide rails is proposed, wherein:

[0017] driving a vehicle on the track, the vehicle carrying an inertial unit, a set of equipment for measuring at least one relative orientation component of at least one of the two rows of rails with respect to the inertial unit, and one or more odometers,

[0018] determining, at least on the basis of a signal generated by the inertial unit, a continuous value of at least one absolute orientation component of the inertial unit in a geostationary reference system,

[0019] For at least one of the two rows of rails being observed, and preferably for each of the two rows of rails being considered as a row of rails being observed:

[0020] determining, at least by the signal generated by the odometer(s), a succession of values ​​of the abscissa of the curve of the vehicle on the row of rails under observation,

[0021] determining, at least on the basis of the signals generated by the measuring device, successive values ​​of at least one relative orientation component of the row of rails under observation with respect to the inertial unit,

[0022] calculating continuous values ​​of at least one absolute orientation component or absolute positioning component of the observed row of rails at least from continuous values ​​of the absolute orientation component of the inertial unit and continuous values ​​of the relative orientation component of the observed row of rails with respect to the inertial unit,

[0023] constructing a function s→G(s) which relates at least some continuous values ​​of the curve abscissa to the concomitant values ​​of the continuous values ​​of the absolute orientation component or the absolute positioning component of the row of rails observed in space,

[0024] Apply a high-pass linear filter or a band-pass linear filter to the function s→G(s) to construct a filter function s→F(s),

[0025] For a series of current curve abscissa values ​​l among the curve abscissa values, the integral I(l) is evaluated over a given curve abscissa interval of the filter function bounded by the reference curve abscissa value 10 and by the current curve abscissa value l.

[0026] [Mathematical formula 1]

[0027] By performing a single spatial integration instead of a double integration of each row of observed guide rails into a filter function linking the curvilinear abscissa of the vehicle to the absolute orientation component or absolute positioning component, all time-dependent effects, in particular drift effects, are eliminated.

[0028] In practice, the continuous curve abscissa values ​​are not necessarily determined at constant distance intervals. In particular, these different signals may be sampled at constant time intervals, preferably synchronized, in order to obtain a good match between the values ​​determined from the signals from the inertial measurement unit, the odometer and the measurement device.

[0029] An inertial unit must be accurate enough to provide an absolute orientation component in a geostationary reference frame, ie without drift. It is therefore a control unit whose gyroscopes are able to detect the projection of the Earth's rotation and whose accelerometers are able to detect the projection of gravity.

[0030] By applying a bandpass filter or highpass filter to the input function s→G(s) prior to the integration operation, potential numerical instabilities that would result from integrating continuous components of the input function are avoided. The linear filter used is preferably a finite impulse response filter of any order N, preferably greater than or equal to 2.

[0031] Preferably, the linear filter is a bandpass filter, preferably in one of the following three frequency bands: 3m to 25m, 25m to 70m, 70m to 150m, or an arrow calculation function. In fact, the same function s→G(s) can naturally be used to construct several filtered functions in parallel, each function for a different wavelength band or filter type.

[0032] In practice, an estimate of the integral is obtained by a discrete sum, preferably by Riemann sum or trapezoidal method, over a given interval, with a step size smaller than 25 cm, and preferably smaller than 1 cm.

[0033] According to one embodiment, the operation of calculating successive values ​​of at least one absolute orientation component or positioning component of the row of rails under observation consists at successive moments of the algebraic sum of the instantaneous value of the absolute orientation component of the inertial unit and the simultaneous instantaneous value of the relative orientation component of each row of rails under observation relative to the inertial unit.

[0034] In one embodiment, the relative orientation component of the observed row of rails with respect to the inertial unit is the orientation angle in the horizontal plane, and the absolute orientation component of the inertial unit is the yaw angle, and the integral I(l) is the alignment parameter. R is the instantaneous value of the angle determined by the measuring device in the horizontal plane between the longitudinal direction of the inertial measurement unit and the direction of the row of rails being observed, and ψ C is the instantaneous value of the yaw angle determined simultaneously by the inertial unit, then the absolute orientation component ψA of the observed row of rails can be expressed as the algebraic sum:

[0035] [Mathematical formula 2]ψ A =ψ R +ψ C

[0036] In another embodiment, the relative orientation component of the observed row of rails with respect to the inertial unit is the orientation angle with respect to the vertical longitudinal plane (V) of the vehicle, and the absolute orientation component of the inertial unit is the pitch angle, and the integral I(l) is the longitudinal horizontal parameter. R is the instantaneous value of the angle determined by the measuring device in the vertical longitudinal plane between the longitudinal direction of the inertial measurement unit and the direction of the row of rails being observed, and θ C is the instantaneous value of the pitch angle determined simultaneously by the inertial unit, then the absolute orientation component ψA of this row of rails can be expressed as the algebraic sum:

[0037] [Mathematical formula 3]θ A =θ R +θ C

[0038] Preferably, the operations of calculating a continuous value of at least one absolute orientation component of one of the two observed rows of guide rails, constructing a function s→G(s), applying a linear filter, constructing a filtered function s→F(s), and estimating the integral I(l) are performed in parallel to obtain an intrinsic alignment coordinate and an intrinsic longitudinal horizontal coordinate.

[0039] In one embodiment, the measuring device delivers at least two simultaneous signals for measuring the lateral distance between two reference points on the vehicle and the row of rails being observed, the two reference points being at a distance (A) greater than 250 mm and preferably greater than 500 mm from each other. If A is the distance between two reference points of the same row of rails being observed, y1 and y2 are the lateral distances measured between the row of rails being observed and each of the reference points, and assuming that the longitudinal axis of the inertial unit is aligned with the longitudinal axis of the row of rails when y1=y2, the measuring device provides a yaw angle ψ measured by the inertial unit relative to the row of rails being observed using the following equation R Access to the relatively oriented components of the composition:

[0040] [Formula 4]

[0041] In one embodiment, the measuring device delivers at least two simultaneous signals for measuring the vertical distances between two reference points on the vehicle and the row of rails being observed, the two reference points being spaced apart from each other by a distance (B) greater than 250 mm and preferably greater than 500 mm. If B is the distance between two reference points of the same row of rails being observed, z1 and z2 are the vertical distances measured between the row of rails being observed and each reference point, and assuming that when z 1＝ When the longitudinal axis of the inertial unit is aligned with the longitudinal axis of the row of rails at z2, the measurement device provides the yaw angle θ of the inertial unit relative to the row of rails being observed using the following equation: R Access to the relatively oriented components of the composition:

[0042] [Formula 5]

[0043] The sensors of the measuring device can operate on different principles (optical, magnetic, capacitive, etc.) which operate linearly and optimally within a relatively narrow operating range. It is therefore beneficial to ensure that the vertical and lateral positioning of the vehicle on the track is always close to the "ideal" alignment position. For this purpose, at least one actuator for correcting the alignment of the vehicle on the track can be controlled as a function of the signal generated by the measuring device or of the continuous values ​​of the relative orientation component of the row of rails under observation relative to the inertial unit, so as to reduce the drift between the signal generated by the measuring device and a predetermined value, or between the continuous values ​​of the relative orientation component of the row of rails under observation and a predetermined value of the relative orientation component of the row of rails under observation. The correction operation is particularly useful for vehicles running on a single pair of wheels.

[0044] In one embodiment, the operation of determining the continuous curvilinear abscissa values ​​of the vehicle on the observed row of rails is performed at least on the basis of the signal generated by the odometer of the odometers associated with the observed row of rails. This operation can be performed for each row of rails if each row of rails is associated with at least one odometer.

[0045] In one embodiment, the operation of determining the abscissa value of the continuous curve of the vehicle on the observed row of rails is performed at least based on the signal generated by the odometer of the odometer not associated with the observed row of rails and the signal generated by the measuring device. If only one row of rails is associated with an odometer, this operation can be performed for the other row of rails.

[0046] In practice, the wheel connected to the odometer(s) may momentarily lose contact with the row of rails being observed, in which case the generated signal no longer provides reliable information about the position of the vehicle relative to the row of rails being observed. In one embodiment, a malfunction of the odometer(s) is detected by comparing a longitudinal acceleration value generated by the inertial unit with an average acceleration value determined from the signal generated by the odometer(s), and / or by comparing an angular velocity value about a vertical axis generated by the inertial unit with an angular velocity value derived from the signal generated by the odometer(s). Preferably, when a malfunction is detected, a safety procedure is executed, in which a continuous curve abscissa value of the vehicle on each of the two rows of rails is determined based on at least the acceleration signal or the angular velocity signal generated by the inertial unit.

[0047] Another aspect of the present invention relates to a system for implementing a method according to the first aspect of the present invention or one of its embodiments, the system comprising a vehicle capable of traveling on a railway track having two rows of parallel guide rails, the vehicle carrying an inertial unit having at least three gyroscopes and three accelerometers, a set of equipment for measuring the relative orientation of each of the two rows of guide rails relative to the inertial unit, and one or more odometers, wherein the system also includes a computing device programmed to perform the following operations: calculate a continuous value of at least one absolute orientation component or positioning component of an observed row of guide rails in the two rows of guide rails, construct a function s→G(s), apply a linear filter, construct a filter function s→F(s), and estimate the integral I(l).

[0048] In one embodiment, the measuring device comprises at least two sensors associated with each of the two rows of rails for measuring the lateral distance between two reference points on the vehicle and the associated row of rails, the two reference points being spaced apart from each other by a distance (A) greater than 250 mm and preferably greater than 500 mm. Each sensor is dedicated to measuring the lateral distance at one of the reference points.

[0049] In one embodiment, the measuring device comprises at least two sensors associated with each of the two rows of rails for measuring the vertical distance between two reference points on the vehicle and the associated row of rails, the two reference points being spaced apart from each other by a distance (B) greater than 250 mm and preferably greater than 500 mm. Each sensor is dedicated to measuring the vertical distance at one of the reference points.

[0050] Other principles for measuring the relative orientation of the inertial unit with respect to each row of rails are also foreseeable. In one embodiment, the measuring device comprises at least one, and preferably at least two, cameras for detecting one or more linear laser beams projected onto each of the plurality of rows of rails. For example, each camera may capture the position of the laser line projected onto the row of rails being observed, wherein the measuring device determines by triangulation the relative vertical and lateral position between the row of rails being observed and the camera, which is placed in the reference frame of the inertial unit.

[0051] In another embodiment, the measuring device comprises at least one and preferably at least two laser rangefinders scanning the multiple rows of rails of the track. Following the principle of laser telemetry, the distance is given by measuring the delay between the emission of a pulse and the detection of a reflected pulse. The projected laser beam is guided by a rotating mirror that scans a spatial plane covering two rows of rails and triangulates each row of rails to obtain a lateral distance measurement and a vertical distance measurement. With two laser rangefinders placed at a distance from each other in the longitudinal direction of the vehicle, it is possible to obtain the required eight dimensions, namely four lateral distances and four vertical distances.

[0052] If desired, the measuring device may also include a track gauge sensor, although this dimension may be derived by measuring the lateral distance between different reference points and the two rows of rails. If desired, the measuring device may also include a track inclination sensor.

[0053] In one embodiment, the vehicle is a two-wheeled cart driven by a machine and connected to the machine via at least three linkages for controlling the attitude and alignment of the cart according to the relative directional components.

[0054] In an alternative embodiment, the vehicle is a cart having at least four wheels. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings, which show:

[0056] Figure 1 , a schematic side view of a system for determining geometric parameters of a railway track according to an embodiment of the present invention;

[0057] Figure 2 , Figure 1 A schematic top view of a system;

[0058] Figure 3 , integrated into Figure 1 Schematic diagram of a distance sensor in a measuring device of the system shown in;

[0059] Figure 4 , a schematic diagram of a method for determining geometric parameters of a track according to an embodiment of the present invention;

[0060] Figure 5 , Figure 4 A visualization of the filtering operation in the method shown in .

[0061] For greater clarity, the same or similar elements are identified by the same reference numerals throughout the drawings. DETAILED DESCRIPTION

[0062] Figure 1 and Figure 2A system 10 for determining at least one geometric parameter of a track 1 having two guide rails 2 is presented, the system comprising a vehicle 12 capable of traveling on the track, coupled to a guide rail machine 14, which may in particular be a machine for laying, repairing or replacing tracks. In this case, the vehicle 12 is a cart comprising a non-deformable chassis 16 resting on a single pair of wheels 18, possibly with a main suspension between the single pair of wheels and the chassis. Preferably, the cart 12 has no propulsion means and is simply pulled or pushed by the guide rail machine 14 as it moves along the track. The coupling 20 linking the cart 12 to the guide rail machine 14 is here constituted by a connection having two ball joints 22 and two cylinders 24, to allow adjustment of the angular orientation of the chassis 16 relative to the guide rail machine 14 and the track 1, in particular in the vertical plane and in the transverse plane. However, it should be noted that the orientation of the chassis 16 relative to the track 1 can be adjusted by other adjustment means, in particular by controlling an actuator on the main suspension arranged between the chassis 16 and these wheels 18. It should also be noted that the wheels 18 are preferably independent in the sense that they rotate independently of each other.

[0063] The trolley 12 is equipped with various measuring means, including at least one odometer 26, for example, mounted on one of the wheels 18 of the trolley 12, in order to determine the distance travelled on the row of rails 2 on which the wheel 18 runs, or the curvilinear abscissa of the trolley 12 relative to the row of rails 2. Preferably, each of the two wheels 18 is equipped with an odometer 26, making it possible to directly determine the curvilinear abscissa of the trolley 12 relative to each of the two rows of rails 2 of the track 1.

[0064] The trolley 12 also comprises a measuring device 28 for determining the orientation of the chassis 16 relative to each row of rails 2 at least in one reference plane of the chassis 16 and preferably in at least two orthogonal planes, namely a horizontal plane H and a longitudinal vertical plane V.

[0065] For this purpose, the measuring device comprises at least two sensors associated with at least one of the two rows of rails 2, and preferably with both of the two rows of rails 2, for measuring a transverse distance 30 between two reference points of the vehicle and the row of rails to which they are associated, the two reference points being spaced a distance A from each other, such as Figure 2 If y1 and y2 are the measured lateral distances between the row of rails 2 under observation and each reference point 30, and assuming that the longitudinal axis of the chassis 16 is aligned with the longitudinal axis of the row of rails 2 when y1=y2, the measuring device provides the yaw angle ψ of the chassis relative to the row of rails under observation in the horizontal plane using the following equation: R Access to the relatively oriented components of the composition:

[0066] [Mathematical formula 6]

[0067] The accuracy of the results naturally increases with the distance A, which is preferably greater than 250 mm, and more preferably greater than 500.

[0068] In a similar manner, for the orientation of the cart chassis viewed in the vertical plane V, the measuring device comprises at least two sensors associated with at least one of the two rows of rails 2, and preferably with both of the two rows of rails 2, for measuring the vertical distances 32 between two reference points of the vehicle and the row of rails to which they are associated, such as Figure 1 If B is the distance between two reference points 32 of the same row of rails being observed, it is preferably selected to be greater than 250 mm, and more preferably greater than 500 mm, and z1 and z2 are the vertical distances measured between the row of rails being observed and each reference point, and it is assumed that when z 1＝ At z2, the longitudinal axis of the chassis 16e is aligned with the longitudinal axis of the row of rails, and the measuring device provides the pitch angle θ of the chassis relative to the row of rails being observed in the vertical longitudinal plane using the following equation: R Access to the relatively oriented components of the composition:

[0069] [Formula 7]

[0070] The distance to this row of rails 2 can be calculated using Figure 3 The non-contact sensors 30, 32 shown are used for measurement, including proximity sensors such as inductive, photoelectric, magnetic, capacitive or ultrasonic sensors. In order to avoid interference between sensors for the same area of ​​a row of rails, two different types of sensors can be selected for lateral and vertical distance measurement.

[0071] An inertial unit 34 having at least three gyroscopes and three accelerometers is attached to the non-deformable chassis 16 of the cart 12; this inertial unit 34 is called a precision inertial unit in the sense that it is able to deliver an absolute orientation signal, i.e. without drift in a geostationary reference system. It is therefore a kind of control unit whose gyroscopes are able to detect the projection of the Earth's rotation and whose accelerometers are able to detect the projection of gravity.

[0072] Equipped in this way, the cart 12 can be used to determine the absolute orientation of the inertial unit 34 in a geostationary reference frame, as well as the relative orientation of each of the rows of rails 2 relative to the chassis 16 and therefore relative to the inertial unit 34 attached thereto. Figure 4 and Figure 5 A specific procedure shown in is proposed to derive from these metrological data the parameters of the geometry of each row of rails 2 in the absolute reference system.

[0073] When the cart 12 is traveling at a low speed, in particular below 10 km / h (the speed may not be constant), and because the machine 14 may slow down or even be stopped for a long time at the speed of the work being performed on the track 1, the signals from the odometer 26, the measuring device 28 and the inertial unit 34 are sampled simultaneously at constant time intervals.

[0074] Continuous values ​​of at least one absolute orientation component of inertial unit 34 in the geostationary reference frame (eg, continuous values ​​of the roll angle and / or continuous values ​​of the pitch angle) are determined based at least on the signal generated by inertial unit 34 (operation 40 ).

[0075] For at least one observed row of the two rows of guide rails 2, and preferably for each of the two rows of guide rails 2 considered as an observed row of guide rails, a continuous curve abscissa value of the vehicle on the observed row of guide rails 2 is determined based on at least the signal generated by the odometer 26 associated with the observed row of guide rails (operation 42).

[0076] Based at least on the signal generated by the measuring device 28, a continuous value is determined for at least one relative orientation component of the observed row of rails 2 relative to the inertial unit 34, preferably a continuous value is determined for the above two components, namely the yaw angle of the chassis relative to the observed row of rails 2 and the pitch angle of the chassis relative to the observed row of rails (operation 44).

[0077] Based on these factors, it is possible to calculate continuous values ​​of at least one absolute orientation or absolute positioning component of the row of rails 2 under observation from at least continuous values ​​of the absolute orientation component of the inertial unit and continuous values ​​of the relative orientation component of the row of rails under observation with respect to the inertial unit. In practice, the algebraic sum of the instantaneous value of the absolute orientation component of the inertial unit and the simultaneous instantaneous value of the relative orientation component of each row of rails observed with respect to the inertial unit is simply performed (operation 46).

[0078] Therefore, if ψ R (t) is the value of the angle determined by the measuring device 28 at the measuring instant t in the horizontal plane between the longitudinal direction of the inertial measurement unit 34 and the direction of the row of rails 2 being observed, and ψ C (t) is the value of the yaw angle determined simultaneously by the inertial unit 34 at the same instant t, then the absolute orientation component ψ of the row of rails being observed A (t) can be expressed as an algebraic sum:

[0079] [Mathematical formula 8]ψ A (t) = ψ R (t)+ψ C (t)

[0080] Similarly, if θ R(t) is the instantaneous value of the angle determined by the measuring device in the vertical longitudinal plane between the longitudinal direction of the inertial measurement unit 34 and the direction of the row of rails 2 being observed, and θ C (t) is the instantaneous value of the pitch angle determined simultaneously by the inertial unit 34, then the absolute orientation component θ of this row of rails A (t) can be expressed as an algebraic sum:

[0081] [Math 9]θ A (t) = θ R (t)+θ C (t)

[0082] It is then possible to construct one or more functions s→G(s) linking at least some of these continuous curvilinear abscissa values ​​to the concomitant values ​​of these continuous values ​​of the absolute orientation component or positioning component of the row of rails observed in space. (Operation 48)

[0083] Thus, for the yaw component of one of the rows of rails, the value s(t) measured by the odometer associated with the row of rails under observation is compared with the value ψ A (t) association to construct the function s→G L Similarly, the value s(t) measured by the odometer associated with the row of rails under observation will be compared to the value θ for all or at least some of the measurement instants t. A (t) association to construct the function s→G T (s).

[0084] Once this step has been completed in the time domain, one or more functions s→G(s) have been constructed in which time no longer appears as a variable. A linear bandpass filter or a highpass filter (which is not a temporal filter but a spatial filter) can then be applied to each function so constructed in order to construct a filtered function s→F(s) (operation 50). The linear filter used is preferably a finite impulse response filter of any order N, preferably greater than or equal to 2, which produces the following linear combination:

[0085] [Formula 10]

[0086] where b k represents the kth order coefficient of the filter transfer function, and si represents the continuous value of the abscissa of the curve of the row of guide rails under observation (1≤i≤n).

[0087] In practice, if the objective is to observe the rail geometry parameters within the wavelength range defined by the standard, at least one bandpass filter will be used in one of the following three bands: 3m to 25m (D1), 25m to 70m (D2), 70m to 150m (D3), or a bandpass filter implemented by a deflection calculation function (CF), and in practice, operation 50 will be performed in parallel for each desired wavelength range among those available wavelength ranges, which is Figure 5 , illustrated by parallel sub-operations 510, 512, 514, 516.

[0088] Finally, it is possible to evaluate (operation 52) for a series of current curve abscissa values ​​l among these curve abscissa values, the integral I(l) of the filter function over a given curve abscissa interval bounded by the reference curve abscissa value 10 and by the current curve abscissa value l.

[0089] [Mathematical formula 11]

[0090] In practice, the integral I(l) is estimated by a Riemann sum or by the trapezoidal method on a given interval, with a step size of less than 25 cm, and preferably less than 1 cm. For example, with a Riemann sum:

[0091] [Mathematical formula 12]

[0092] Where S0 = l0 and S P =l is the limit of the integrated integral.

[0093] If necessary, this operation 52 is performed in parallel for each wavelength range being observed, and thus the sub-operations 520, 522, 524, 526 are performed in parallel.

[0094] In case the relative orientation component of the observed row of rails 2 with respect to the inertial unit 34 is the orientation angle in the horizontal plane and the absolute orientation component of the inertial unit is the yaw angle, the integral I(l) will be the alignment parameter.

[0095] In case the relative orientation component of the observed row of rails 2 with respect to the inertial unit 34 is the orientation angle with respect to the vertical longitudinal plane of the vehicle and the absolute orientation component of the inertial unit is the pitch angle, the integral I(l) will be the longitudinal horizontal parameter.

[0096] In practice, the calculations may be performed in real time by a computer onboard vehicle 12 , on machine 14 , or remotely located.

[0097] In parallel with these calculation operations, the signal generated by the measuring device 28 or the continuous value of the relative orientation component of the row of guides 2 observed relative to the inertial unit 34 can be used to control the cylinder 24 in order to couple the trolley to the machine, with the aim of minimizing the misalignment between the chassis 16 of the trolley 12 and the rails 1.

[0098] When observing the alignment in the horizontal plane relative to the longitudinal direction, it is possible, for example, to construct a negative feedback loop which aims to convert the angle ψ observed for one of the rows of rails 2 to R Minimize, or more simply minimize the absolute value of the difference observed on one row of rails 2, y1-y2|. When observing two rows of rails, a feedback loop can be constructed that aims to minimize the sum of the absolute values ​​of the deviations observed for each of the two rows of rails: (y1-y2|+|y1-y2)

[0099] Likewise, when observing the alignment in the horizontal plane relative to the longitudinal direction, it is possible, for example, to construct a negative feedback loop that aims to convert the angle θ observed for one of the rows of rails to R Minimize, or more simply minimize the absolute value of the differences observed on one row of rails, |z1-z2|. When observing two rows of rails, or aim to minimize the sum of the absolute values ​​of the deviations observed for each of the two rows: (z1-z2|+|z1-z2|)

[0100] If necessary, a failure of the odometer(s) 26 can be detected by comparing the longitudinal acceleration value generated by the inertial unit 34 with an average acceleration value determined from the signal generated by the odometer(s) 26, and / or by comparing the angular velocity value about the vertical axis generated by the inertial unit 34 with an angular velocity value derived from the signal generated by the odometer(s) 26. When a failure is detected, a degraded mode operating procedure is executed, in which continuous curvilinear abscissa values ​​of the vehicle 12 on each of the two rows of guideways 2 are determined based on at least the acceleration or angular velocity signal generated by the inertial unit 34.

[0101] Naturally, the examples shown in the drawings and discussed above are provided for illustrative and non-limiting purposes only. It is expressly provided that it is possible to combine the different illustrated embodiments in order to provide other embodiments.

[0102] As stated in the description of the invention, other principles for measuring the relative orientation of the inertial unit with respect to each row of rails are also foreseeable.

[0103] It is also possible to equip the cart with a single odometer, making it possible to directly measure the curvilinear abscissa of one of the multiple rows of guide rails. The operation of determining the successive curvilinear abscissa values ​​of the opposite row of guide rails can then be performed based on at least the signal generated by the odometer and the signal generated by the measuring device.

[0104] The above process of determining track geometry can also be performed using a four-wheeled cart, or more generally, using a guideway vehicle that can rest on multiple wheel pairs or bogies. If desired, the chassis to which the inertial unit is attached can be linked to the wheels via one or more suspension stages (e.g., primary suspension and / or secondary suspension).

[0105] In these cases, the apparatus for measuring the relative orientation of each row of rails with respect to the inertial measurement unit will preferably use measurement principles other than those described so far.

[0106] In one embodiment, the measuring device comprises at least one, and preferably at least two, cameras for detecting one or more linear laser beams projected onto each of the plurality of rows of rails. For example, each camera is fixed in a fixed manner to a chassis carrying an inertial unit, in the reference frame of the inertial unit, and is oriented to aim at and capture the position of the laser line projected onto the row of rails being observed, the measuring device determining by triangulation the relative vertical and lateral position between the row of rails being observed and the camera.

[0107] In another embodiment, the measuring device comprises at least one and preferably at least two laser rangefinders, which are also positioned in the reference frame of the inertial unit so as to scan the rows of rails of the track. Following the principle of laser telemetry, the distance is given by measuring the delay between the emission of a pulse and the detection of a reflected pulse. The projected laser beam is guided by a rotating mirror, which scans a spatial plane covering two rows of rails and triangulates each row of rails to obtain a lateral distance measurement and a vertical distance measurement. With two laser rangefinders placed at a distance from each other in the longitudinal direction of the vehicle, it is possible to obtain the required eight dimensions, namely four lateral distances and four vertical distances.

[0108] In another variant, the measuring device comprises at least one time-of-flight (ToF) camera placed in the reference frame of the inertial unit, making it possible to observe the three-dimensional scene in its field of view. Since the field of view of this type of camera is relatively narrow, it is advantageous to use one camera of this type per row of rails.

Claims

1. A method for determining at least one geometric parameter of a railway track (1) having two rows of guide rails (2), wherein: driving a vehicle (10) on the track (1), the vehicle carrying an inertial unit (34), a set of equipment (28) for measuring at least one relative orientation component of at least one of the two rows of rails relative to the inertial unit, and one or more odometers (26), determining a continuous value of at least one absolute orientation component of the inertial unit (34) in a geostationary reference system at least based on a signal generated by the inertial unit (34), For at least one of the two rows of guide rails (2) being observed, and preferably for each of the two rows of guide rails (2) being regarded as a row of guide rails being observed: i) determining, at least on the basis of the signal generated by the odometer (26), successive values ​​of the curve abscissa value of the vehicle on the row of rails (2) under observation, ii) determining, at least on the basis of the signal generated by the measuring device (28), a continuous value of at least one relative orientation component of the row of rails under observation relative to the inertial unit (34), iii) calculating at least one continuous value of an absolute orientation component or an absolute positioning component of the observed row of rails (2) based at least on continuous values ​​of the absolute orientation component of the inertial unit (34) and continuous values ​​of a relative orientation component of the observed row of rails (2) relative to the inertial unit (34), Features: iv) constructing a function s→G(s) which relates at least some continuous values ​​of the curve abscissa to the concomitant values ​​of the continuous values ​​of the absolute orientation component or the absolute positioning component of the row of rails viewed in space, v) applying a high-pass linear filter or a band-pass linear filter to the function s→G(s) to construct a filter function s→F(s), vi) evaluating, for a series of current curve abscissa values ​​l among said curve abscissa values, an integral I(l) over a given curve abscissa interval of said filter function bounded by the reference curve abscissa value 10 and by said current curve abscissa value l, [Mathematical formula 13] 2. The method according to claim 1, characterized in that The linear filter is a bandpass filter, preferably in one of the following three frequency bands: 3m to 25m, 25m to 70m, 70m to 150m, or an arrow calculation function.

3. The method according to any one of the preceding claims, characterized in that The integral I(l) is estimated by means of a Riemann sum or a trapezoidal method on a given interval, with a step size smaller than 25 cm and preferably smaller than 1 cm.

4. The method according to any one of the preceding claims, characterized in that The operation of calculating the successive values ​​of at least one absolute orientation component or positioning component of the row of rails (2) under observation consists at successive moments of the algebraic sum of the instantaneous value of the absolute orientation component of the inertial unit and the simultaneous instantaneous value of the relative orientation component of each row of rails under observation relative to the inertial unit.

5. The method according to any one of the preceding claims, characterized in that The relative orientation component of the observed row of rails (2) relative to the inertial unit (34) is the orientation angle in the horizontal plane, and the absolute orientation component of the inertial unit is the yaw angle, the integral I(l) being the alignment parameter.

6. The method according to any one of the preceding claims, characterized in that The relative orientation component of the observed row of rails (2) relative to the inertial unit (34) is the orientation angle in the vertical plane (V) of the vehicle (12), and the absolute orientation component of the inertial unit is the pitch angle, the integral I(l) being the longitudinal horizontal parameter.

7. The method according to any one of the preceding claims, characterized in that For each row of rails (2) observed, the measuring device generates at least two simultaneous signals for measuring the lateral distance between two reference points (30) on the vehicle (12) and the row of rails (2) observed, the two reference points (30) being separated from each other by a distance (A) greater than 250 mm, and preferably greater than 500 mm.

8. The method according to any one of the preceding claims, characterized in that For each row of rails (2) observed, the measuring device generates at least two simultaneous signals for measuring the lateral distance between two reference points (32) of the vehicle (12) and the row of rails (2) observed, the two reference points (32) being separated from each other by a distance (B) greater than 250 mm and preferably greater than 500 mm.

9. The method according to any one of the preceding claims, characterized in that At least one actuator (24) for correcting the alignment of the vehicle (12) on the track (1) is controlled based on the signal generated by the measuring device (28) or the continuous value of the relative orientation component of the observed row of rails (2) relative to the inertial unit (34) so ​​as to reduce the drift between the signal generated by the measuring device (38) and a predetermined value or the continuous value of the relative orientation component of the observed row of rails (2) and a predetermined value of the relative orientation component of the observed row of rails (2).

10. The method according to any one of the preceding claims, characterized in that The operation of determining successive curvilinear abscissa values ​​of the vehicle (12) on the observed row of rails (2) is performed based at least on a signal generated by an odometer (26) of the odometers associated with the observed row of rails (2).

11. The method according to any one of the preceding claims, characterized in that An operation of determining the abscissa value of a continuous curve of the vehicle on the observed row of rails (2) is performed based at least on a signal generated by one of the odometers not associated with the observed row of rails (2) and a signal generated by the measuring device (28).

12. The method according to any one of the preceding claims, characterized in that Failure of the odometer (26) is detected by comparing a longitudinal acceleration value generated by the inertial unit (34) with an average acceleration value determined based on the signal generated by the odometer (26), and / or by comparing an angular velocity value about a vertical axis generated by the inertial unit (34) with an angular velocity value derived from the signal generated by the odometer (26).

13. The method according to claim 12, characterized in that When a fault is detected, a safety procedure is executed, wherein a continuous curve abscissa value of the vehicle (12) on each of the two rows of guide rails (2) is determined based on at least an acceleration signal or an angular velocity signal generated by the inertial unit (34).

14. A system for implementing the method according to any of the preceding claims, the system comprising a vehicle capable of travelling on a railway track (1) having two rows of parallel rails (2), the vehicle (12) carrying an inertial unit (34) having at least three gyroscopes and three accelerometers, a set of equipment (28) for measuring the relative orientation of each of the two rows of rails (2) relative to the inertial unit (34), and one or more odometers (26), characterized in that The system also includes a computing device programmed to perform the following operations: calculate a continuous value of at least one absolute orientation component or positioning component of the observed row of guide rails (2) of the two rows of guide rails, construct a function s→G(s), apply a linear filter, construct a filter function s→F(s), and estimate the integral I(l).

15. The system according to claim 14, characterized in that The measuring device (28) comprises at least two sensors associated with each of the two rows of rails (2) for measuring the lateral distance (30) between two reference points on the vehicle and the associated row of rails, the two reference points being spaced apart from each other by a distance (A) greater than 250 mm and preferably greater than 500 mm.

16. The system according to any one of claims 14 to 15, characterized in that The measuring device (28) comprises at least two sensors associated with each of the two rows of guide rails (2) for measuring the vertical distance (32) between two reference points on the vehicle and the associated row of guide rails (2), the two reference points being spaced apart from each other by a distance (B) greater than 250 mm and preferably greater than 500 mm.

17. A system according to any one of claims 14 to 16, characterized in that The measuring device (28) comprises at least one, and preferably at least two, cameras for detecting one or more linear laser beams projected onto each of the plurality of rows of rails.

18. A system according to any one of claims 14 to 17, characterized in that The measuring device (28) comprises at least one, and preferably at least two, laser rangefinders that scan the rows of rails of the track.

19. The system according to any one of claims 14 to 18, characterized in that The vehicle (12) is a two-wheeled cart (18) driven by a machine (14) and connected to the machine via at least three links (22, 24) for controlling the attitude and alignment of the cart (12) according to relative directional components.

20. The system according to any one of claims 14 to 18, characterized in that The vehicle (12) is a cart having at least four wheels.

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