Method for estimating the longitudinal acceleration of at least one railway vehicle

Abstract

A method for estimating the longitudinal acceleration of at least one rail vehicle by means of an acceleration sensor means (100) is described, the method comprising the step of performing a calibration phase comprising the steps of: solving the following system to determine the values ​​of the first direction cosine k1, the second direction cosine k2 and the third direction cosine k3: [Equation 1] JPEG2023520169000025.jpg19155 - Following the calibration stage, the first direction cosine k1 and the first acceleration a x (t i1 ) multiplied by the second direction cosine k2 and the second acceleration a y (t i1 ) and multiplying by the third direction cosine k3 and the third acceleration a z (t i1 ) and the sum of the multiplications is the estimated vertical acceleration value a lon (t i1 ) step

Description

Technical Field

[0001] The present invention generally belongs to the field of railway vehicles, and in particular, the present invention relates to a method for estimating the longitudinal acceleration of at least one railway vehicle.

Background Art

[0002] Slip (also called slide, skid, or sliding) is understood to be a state where there is a difference between the rotational speed of the axle and the running speed of the vehicle. This difference is defined as the slip speed.

[0003] The slip speed can be calculated using the following formula.

Equation

[0004] Here, V RV is the longitudinal running speed of the railway vehicle, ω axle is the angular velocity of the axle, and R is the radius of the wheel.

[0005] Modern railway vehicles generally include an electronic system with a subsystem for controlling wheel slip, and this subsystem is configured to intervene when the vehicle is in the traction phase or when the vehicle is in the braking phase. This type of subsystem is known as an anti-slip or anti-slip system and is also known as a WSP (Wheel Slide Protection) system.

[0006] A system for controlling the adhesion of wheels in an anti-slip function according to the prior art is schematically shown in FIG. 1, which shows a vehicle having n controlled axles A1, A2,..., An. The axles A1, A2,..., An include associated shafts S1, S2,..., Sn and associated pairs of wheels W1, W2,..., Wn that are rotatably integrated therewith.

[0007] In the drawings, generally only one wheel of each axle is shown.

[0008] The WSP system of FIG. 1 typically includes an electronic control unit ECU based on a microprocessor structure, which receives tachometer signals regarding the angular velocities of each axle A1, A2, ..., An from sensors SS1, SS2, ..., SSn respectively associated with these axles. Further, the electronic control unit ECU is connected to torque control devices TC1, TC2, ..., TCn respectively associated with the relevant axles A1, A2, ..., An.

[0009] When torque is applied during the traction or braking phase in a situation where adhesion has decreased and the wheels of one or more axles are in an initial skidding state, the electronic control unit ECU is configured to adjust the torque applied to each axle according to a predetermined algorithm. The torque is adjusted throughout the entire period of the decreased adhesion state in any case, for the purpose of restoring adhesion, so as to prevent the axles from completely stopping and, in some cases, to put each axle in a controlled sliding state.

[0010] The instantaneous speed V RV (t) of the vehicle is clearly fundamental for accurately controlling skidding.

[0011] One known method for accurately tracking the speed of a railway vehicle requires maintaining a floating axle, i.e., an axle that is not receiving traction or braking torque. This is necessary to ensure that the measurement of its speed is the best reproduction of the actual speed V real of the railway vehicle. This solution is particularly effective when the adhesion between the wheel and the track is particularly low. In this case, during traction or braking, all the wheels may skid, and thus, correct information regarding the actual speed of the vehicle cannot be provided. A floating wheel that is not receiving traction or braking torque can continue to accurately track the speed of the vehicle.

[0012] Modern railway vehicle structures, especially subway structures, tend to have a very limited configuration, for example, they are composed of two-car formations. In this case, the use of "idling" axles will significantly reduce the tractive force and braking force of the train.

[0013] Figure 2(a) shows an exemplary configuration composed of two independent vehicles, and Figure 2(b) shows an exemplary configuration composed of two vehicles constrained by Jacobs bogies. It is clear that the use of idling axles reduces the tractive force and braking capacity by 12.5% in the first case and 16.7% in the second case.

[0014] In the prior art, there are also systems based on acceleration sensors that measure the forward speed of a vehicle.

[0015] With the popularization and price reduction of MEMS ("Micro-Electro-Mechanical System"), more and more electronic devices incorporate acceleration sensors, typically three-axis acceleration sensors, on the substrate regardless of their main applications.

[0016] The use of acceleration sensors to estimate the longitudinal acceleration of a vehicle is in principle easily applicable.

[0017] The longitudinal acceleration is understood to mean the acceleration in the direction of travel of the vehicle. By integrating this longitudinal acceleration over time, the longitudinal speed, that is, the running speed of the vehicle, can be obtained. It is clear that this method is not clearly affected by the above-mentioned slipping problems that the axle may experience when the adhesion decreases.

[0018] Referring to Figure 3, the railway vehicle 1 travels on the track 3 and is equipped with an acceleration sensor 2.

[0019] In the Earth / gravity reference system, the axis z is defined as the direction of the gravitational acceleration, and the axes x and y can be defined as transverse directions on a plane perpendicular to z.

[0020] However, in a reference system integrated with the vehicle, the axis y’ can be defined as the longitudinal direction of the vehicle, the axis x’ can be defined as the lateral direction of the vehicle, and the axis z’ can be defined as the direction perpendicular to the plane of the vehicle (the “floor”).

[0021] Furthermore, x”, y” and z” can be defined as the sensitive axes of the triaxial acceleration sensor.

[0022] Now, considering the ideal case where the sensor is installed integrally with the vehicle and the axes are perfectly aligned with the vehicle's axes, it is as follows.

Number

[0023] Also, considering a specific case where the vehicle 1 is traveling on a section of the track 3 that is completely straight and has no gradient, it is as follows.

Number

[0024] Under such ideal conditions, the longitudinal acceleration of the vehicle can be directly estimated from the measured values of the following accelerometer.

Number

[0025] Next, the traveling speed of the vehicle can be calculated as the time integral of the acceleration value.

Number

[0026] Or, in the case of a separate acquisition system, it is as follows.

Number

[0027] However, this methodology, which is greatly simplified by the above assumptions, cannot be applied in actual situations.

[0028] Even if it is precisely implemented, the acceleration sensor integrated on the electronic circuit board mounted on the vehicle does not have sensing axes x″, y″, and z″ that are perfectly aligned with the vehicle's axes x′, y′, and z′.

[0029] Furthermore, the hypothesis that vehicle 1 is traveling in a section of track 3 that is perfectly straight and has no gradient is not actually applicable either, because the railway vehicle may travel in sections with curves and / or sections with non-zero gradients.

[0030] The invalidity of the aforementioned assumptions opens the way to a geometric scenario where the three reference systems (gravity, vehicle, and accelerometer) have relative angles on the three axes.

[0031] The rotation angles between the vehicle reference system and the gravity reference system can be defined as α, β, and φ respectively with respect to the axes x, y, and z.

[0032] The rotation angles between the accelerometer reference system and the vehicle reference system can be defined as α′, β′, and φ′ respectively with respect to the axes x, y, and z.

[0033] The angles α, β, and φ are not known to the electronic unit that acquires the accelerometer, but since they depend only on the mounting of the accelerometer with respect to the vehicle, they are constant over time.

[0034] The angles α′, β′, and φ′ are not only unknown to the electronic unit that acquires the accelerometer, but also depend on the curvature and gradient of the local section of the track, so they are not constant over time.

[0035] Since the angles α, β, φ and the angles α’, β’, φ’ are unknown and independent of each other, the problem of determining the longitudinal acceleration of a vehicle from the measured values of a triaxial accelerometer mounted on the vehicle may not be solvable analytically and / or geometrically.

[0036] For example, WO2017042138 proposes an analytical / geometrical method for determining the orientation of an accelerometer with respect to a vehicle equipped with the accelerometer. This method assumes the following are available. - “Free state”, i.e., a state where the accelerometer is only subject to gravity when the railway vehicle is stationary or moving at a constant speed - Availability of a reliable speed information source outside the accelerometer for the railway vehicle (even if discontinuous)

[0037] The availability of a reliable speed measurement value of the railway vehicle outside the accelerometer, even if discontinuous, is reasonable considering that it is reliable in all cases where the angular velocity of the axle (measured by the sensor SS in FIG. 1) is still the majority and the adhesion has not deteriorated. The roles of the accelerometer and the method for estimating the speed of the railway vehicle from it would be used in a situation where all the axles are in a slipping state and their angular velocities do not represent the speed of the railway vehicle or train, and the adhesion has decreased.

[0038] However, the method proposed in WO2017042138 is basically based on two assumptions. 1) In the “free state”, the vehicle is running on a completely horizontal track (gradient is zero). 2) At the stage of using the external speed of the accelerometer, the railway vehicle or train is completely in the straight section of the track. Therefore, the lateral acceleration component (axis x) is ignored, and instead, it exists in the curved section.

[0039] The assumptions on which WO2017042138 is based are very restrictive and do not guarantee the operation of this method in actual applications.

[0040] The actual speed V of the vehicle during brakingV The most commonly used algorithm for estimating (t) usually uses a function as follows.

Number

[0041] On the other hand, in the case of traction, the following function is used.

Number

[0042] Here, a max represents the maximum acceleration allowed during vehicle operation, which has a positive sign in the traction state and a negative sign in the braking state. The contributions (V v (T j-1 ) + a max ·T) in equations (5) and (6) are used to include variations in the axle speed V V (t) within the physical limits allowed by the train when excessive instantaneous and simultaneous variations in the axle speed due to a reduced adhesion state, especially during traction or braking, may lead to significant losses in the speed V V (t) calculated using equations (5) and (6).

[0043] More accurate variants of equations (5) and (6) are known, but they are still based on instantaneous measurements of the individual axle speeds. Here, it is clear that the use of idling axles makes equations (5) and (6) extremely accurate when all axles receiving torque are in the slipping stage.

Summary of the Invention

Problems to be Solved by the Invention

[0044] Accordingly, an object of the present invention is to provide a method for estimating the longitudinal acceleration of at least one railway vehicle and a method for estimating the longitudinal speed of at least one railway vehicle, which methods enable the measurement of the longitudinal acceleration and longitudinal speed of the vehicle, respectively, even in a state where all the axles of the vehicle are in a slipping stage caused by reduced adhesion.

[0045] Accordingly, a further object of the present invention is to accurately evaluate the longitudinal forward speed by completely restoring the use of the slipping axles for traction and braking purposes, especially when the adhesion is low, enabling the axles to accurately track the speed of the train while increasing the traction and braking forces of the train.

[0046] The method for estimating the longitudinal speed and the method for estimating the longitudinal acceleration can be applied to both the slipping situation (negative V slippage ) in the traction stage and the slipping situation (positive V slippage ) in the braking stage.

[0047] The present invention can most accurately know the longitudinal speed of a railway vehicle, for example, facilitating and improving the control system, anti-slip system, and operation of the running standard installed on the substrate.

[0048] The above and other objects and advantages are achieved, according to one aspect of the present invention, by a method for estimating the longitudinal acceleration of at least one railway vehicle having the features defined in claims 1 and 2, respectively, and a method for estimating the longitudinal acceleration of at least one railway vehicle having the features defined in claims 10 and 12, respectively. Preferred embodiments of the present invention are defined in the dependent claims, the content of which should be understood as an integral part of this specification.

Brief Description of the Drawings

[0049] Next, functional and structural features of some preferred embodiments of the method for estimating the longitudinal speed of at least one railway vehicle according to the present invention will be described. Refer to the accompanying drawings.

Figure 1

Figure 2a

Figure 2b

Figure 3

Figure 4

Figure 5

[0050] Before detailing a plurality of embodiments of the present invention, it should be made clear that the present invention is not limited to the structural details and component configurations described in the following specification or shown in the figures in its application. The present invention can take other embodiments and can be actually implemented or constructed in various different ways. It should also be understood that the expressions and technical terms are for the purpose of explanation and should not be construed as limitations. "Include", "comprise", or their variations should be understood to include the elements described below and their equivalents, as well as their additional elements and their equivalents.

[0051] The present invention proposes a method for calculating the estimated longitudinal acceleration of at least one railway vehicle, and a method for calculating the estimated longitudinal speed of a railway vehicle using acceleration sensor means, such as triaxial acceleration sensor means.

[0052] The method for estimating the longitudinal acceleration of at least one railway vehicle is the independent longitudinal reference speed V of the railway vehicle below refIt is necessary to be able to utilize the measured value of the train speed independent of the accelerometer, even if it is available discontinuously. A method for estimating the longitudinal acceleration of at least one railway vehicle is based on obtaining the direction cosines of a 3×3 orientation matrix such that multiplying the measurements from sensors having three orthogonal axes results in the estimated longitudinal acceleration of the vehicle. By integrating the estimated longitudinal acceleration of the vehicle, the estimated longitudinal speed of the vehicle can be obtained.

[0053] The main equations used are as follows.

Number

Number

[0054] In order to be able to calculate the differentiation of the independent longitudinal reference speed at time point t, this independent longitudinal reference speed must be measured for at least one time interval including time point t. For example, the interval can be 20 ms, 100 ms, etc.

[0055] The unknowns in this equation are k1, k2, k3.

[0056] Equation (7) is valid only when the above-mentioned independent longitudinal reference speed v ref is available.

[0057] Regardless of the technique used, solving equation (7) when the independent longitudinal reference speed v ref is available means that the coefficients k1, k2, and k3 can be dynamically updated such that a linear combination with the acceleration measured by the sensor results in the estimated longitudinal acceleration of the railway vehicle or train.

[0058] Hereinafter, a first embodiment of a method for estimating the longitudinal acceleration of at least one railway vehicle by the acceleration sensor means 100 will be described. The acceleration sensor means 100 measures a first acceleration a x along a first axis x, a second acceleration a y along a second axis y, and a third acceleration a z along a third axis z. The first axis x, the second axis y, and the third axis z are orthogonal to each other.

[0059] A method for estimating the longitudinal acceleration of at least one railway vehicle includes a first calibration step of the following steps include . - At a first calibration time t ref when the independent longitudinal reference speed v of the railway vehicle is available, measure a first value of the first acceleration a c1 (t x ), a first value of the second acceleration a c1 (t y ), and a first value of the third acceleration a c1 (t z ), where the independent longitudinal reference speed v c1 is independent of the acceleration sensor means (100). ref - At a second calibration time t ref when the independent longitudinal reference speed v of the railway vehicle is available, where the second calibration time is different from the first calibration time t c2 , measure a second value of the first acceleration a c1 (t x ), a second value of the second acceleration a c2 (t y ), and a second value of the third acceleration a c2 (t z ), and a second value of the third acceleration a c2Measuring the second value of (). - The independent longitudinal reference speed v of the railway vehicle ref At the third calibration time point t when it is available c3 At which the third calibration time point is the first calibration time point t c1 And the second calibration time point t c2 Different from, the first acceleration a x (t c3 ) The third value of, the second acceleration a y (t c3 ) The third value of, the third acceleration a z (t c3 ) Measuring the third value of - The first calibration time point t c1 The independent longitudinal reference speed v measured at ref (t c1 ) From the first value of, the first independent longitudinal reference acceleration at the first calibration time point t c1 a degree a ref (t c1 ) Calculating the value of - The second calibration time point t c2 The independent longitudinal reference speed v measured at ref (t c2 ) From the second value of, the second independent longitudinal reference acceleration at the second calibration time point t c2 a degree a ref (t c2 ) Calculating the value of - The third calibration time point t c3 The independent longitudinal reference speed v measured at ref (t c3 ) From the third value of, the third independent longitudinal reference acceleration at the third calibration time point t c3 a degree a ref (t c3 ) Calculating the value of - Solving the following system to determine the values of the first direction cosine k1, the second direction cosine k2, and the third direction cosine k3.

Equation

[0060] Obviously, the calibration points are all obtained in a single continuous calibration interval in which the independent longitudinal reference speed of the railway vehicle is available, or the calibration points can be obtained in several calibration intervals in which the independent longitudinal reference speed of the railway vehicle is available. In the second case, the various calibration intervals can be delimited by intervals in which the independent longitudinal reference speed of the railway vehicle is not available.

[0061] In other words, if the independent longitudinal reference speed v ref is available, it is possible to measure the values of a c1 , t c2 , t c3 at three different calibration points t x , a y , a z and v ref and a system of three equations can be formed. This system of three equations with three unknowns can be solved by both analytical and numerical methods. Also, by obtaining measurement values at further points in time (i.e., more than three times), the accuracy of the solutions k1, k2, k3 can be recursively improved and updated over time.

[0062] In this case, saying that the independent longitudinal reference speed v ref is independent of the acceleration sensor means 100 is understood to mean that the independent longitudinal reference speed is not the speed obtained by the acceleration sensor means.

[0063] In this case, saying that the independent longitudinal reference speed v ref is available means that the independent longitudinal reference speed v ref is accessible and reflects the actual longitudinal speed at which the railway vehicle is moving along the track, and can be understood to mean that it can be used in a method for estimating the longitudinal acceleration of at least one railway vehicle which is the subject of the present invention.

[0064] Also, the method for estimating the longitudinal acceleration of at least one railway vehicle comprises a further measurement stage following the calibration stage.

[0065] This measurement stage comprises the following steps. - At least a first measurement time point t when the independent longitudinal reference speed of the railway vehicle is not available i1 Determining an estimated longitudinal acceleration value at lon (t i1 ) for at least one railway vehicle.

[0066] The estimated longitudinal acceleration value a lon (t i1 ) corresponds to the measurement time point t i1 and is estimated by the following sum. - Multiplication of the first direction cosine k1 determined in the calibration phase by the fourth value of the first acceleration a i1 acquired at the first measurement time point t x (t i1 ). - Multiplication of the second direction cosine k2 determined in the calibration phase by the fourth value of the second acceleration a i1 acquired at the first measurement time point t y (t i1 ). - Multiplication of the third direction cosine k3 determined in the calibration phase by the fourth value of the third acceleration a i1 acquired at the first measurement time point t z (t i1 ).

[0067] In an alternative embodiment, referring to FIG. 4, the method for estimating the longitudinal speed of at least one railway vehicle again comprises a calibration phase including the following steps. - For at least a first calibration time point t ref when the independent longitudinal reference speed v c1 of the railway vehicle is available, estimating an estimated longitudinal acceleration value a lon (t c1 ) of at least one railway vehicle by means of a linear filter. In this case, the independent longitudinal reference speed v ref is also independent of the acceleration sensor means 100.

[0068] The estimated longitudinal acceleration value a lon (t c1 ) corresponds to the calibration time point t c1It is for, and is estimated by the following sum by a linear filter. - The first direction cosine k1 having a predetermined value and the first calibration time point t c1 The first acceleration a obtained at x (t c1 ) The multiplication with the first value of. - The second direction cosine k2 having a predetermined value and the first calibration time point t c1 The second acceleration a obtained at y (t c1 ) The multiplication with the first value of. - The third direction cosine k3 having a predetermined value and the first calibration time point t c1 The third acceleration a obtained at z (t c1 ) The multiplication with the first value of.

[0069] In this embodiment, the calibration stage also includes the following steps. - The estimated longitudinal acceleration value a for the first calibration time point t c1 (t lon ) And the first calibration time point t c1 For, the first calibration time point t c1 At the independent longitudinal reference velocity value v measured at c1 The first calibration time point t ref (t c1 ) The independent longitudinal reference acceleration value a determined from the first value of ref (t c1 ) To determine the estimation error Eror by the difference with. - By the adaptive filter (104), to minimize the estimation error, to determine updated values of each of the first direction cosine k1, the second direction cosine k2, and the third direction cosine k3.

[0070] When the calibration stage is started for the first time, the values of the first direction cosine k1, the second direction cosine k2, and the third direction cosine k3 can be preset. For example, they can be predetermined default values that are gradually adjusted as calibration is performed at various calibration time points, or can also be predetermined values equal to the values of the first direction cosine k1, the second direction cosine k2, and the third direction cosine k3 calibrated during the previous operation of the railway vehicle.

[0071] In other words, solving the equation can be based on the use of an adaptation algorithm. The error can be obtained by comparing the output of the linear filter with the reference longitudinal acceleration value derived by deriving the independent longitudinal reference speed v ref This error is used by the adaptation filter to dynamically recalculate the coefficients of the linear filters k1, k2, k3 in order to recursively minimize the error.

[0072] Also in this alternative embodiment, the method for estimating the longitudinal speed of at least one railway vehicle also comprises a further measurement step following a calibration step.

[0073] This measurement step comprises the following steps. - For at least a first measurement time t when the independent longitudinal reference speed of the railway vehicle is not available by means of a linear filter, i1 determining an estimated longitudinal acceleration value a lon (t i1 ) of at least one railway vehicle.

[0074] The estimated longitudinal acceleration value a lon (t i1 ) relates to the measurement time t i1 and is estimated by the following sum. - Multiplying the updated value of the first direction cosine k1 determined in the calibration step by the value of the first acceleration a i1 acquired at the first measurement time t x (t i1 ). - Multiplying the updated value of the second direction cosine k2 determined in the calibration step by the value of the second acceleration a i1 acquired at the first measurement time t y (t i1 ). - Multiplying the updated value of the third direction cosine k3 determined in the calibration step by the value of the third acceleration a i1 acquired at the first measurement time t z (t i1 ).

[0075] Referring to FIG. 5, the available time point t av can be defined as the last time point when the independent longitudinal reference speed v ref is available. The time points following the available time point t av are the time points when the independent longitudinal reference speed v ref is no longer available.

[0076] The independent longitudinal reference speed v av detected at the time point t ref (t av ) is the last available and reliable value of the independent longitudinal reference speed v ref .

[0077] Also, the return to the available time point t ret_av >t av can be defined as the first time point when the independent longitudinal reference speed v ret_av becomes available again. ref

[0078] The measurement time point t i1 can coincide with the return to the available time point t ret_av .

[0079] The following equation is applicable only during the period when the independent longitudinal reference speed v ref is available, i.e., during the periods (t < t av ) and (t > t ret_av ).

Equation

[0080] By solving this equation, the coefficients k1, k2, k3 are dynamically updated until the available time point t av . During the period between t av and t ret_av , the values of k1, k2, k3 are frozen at the last values updated at the available time point t av , k1(t av ), k2(t av ), k3(t av ). Then, for t > t avBy solving Equation (7), the values of k1, k2, and k3 can be dynamically updated.

[0081] For example, at the first measurement time point t i1 may coincide with the time point when the independent longitudinal reference speed v ref (t ret_av ) becomes available again after it becomes unavailable.

[0082] The adaptive filter may be configured to determine updated values of the first direction cosine k1, the second direction cosine k2, and the third direction cosine k3 via an adaptive algorithm based on the least squares method, LMS.

[0083] For all the above-described embodiments, the calibration phase may be repeated for a plurality of calibration time points, for example, the second calibration time point t i2 , the third calibration time point t i3 ,.., the nth calibration time point t in .

[0084] Obviously, the calibration step may be performed at the first ignition of each at least one railway vehicle.

[0085] Hereinafter, the independent longitudinal reference speed v of the railway vehicle ref will be exemplified.

[0086] For example, the independent longitudinal reference speed v ref may be a longitudinal speed obtained from the angular velocity of the axle of the railway vehicle. In this case, the independent longitudinal reference speed v ref may be available when the axle is not slipping.

[0087] In a further embodiment, the independent longitudinal reference speed v of the railway vehicle ref is the longitudinal speed of the railway vehicle provided by the positioning means. In this case, the independent longitudinal reference speed v ref may be available when the positioning means communicates with the satellite. The positioning means may be a GPS system / device that communicates using a signal suitable for obtaining position information and thus the moving speed of the train. The independent longitudinal reference speed v refFor example, it may not be available when a railway vehicle is in a tunnel and cannot communicate with a satellite.

[0088] In a further aspect of the present invention, the estimated longitudinal acceleration a lon is determined for a plurality of measurement times t ref at which the independent longitudinal reference speed v i1 of the railway vehicle is available, for example, the second measurement time t i2 , t in ,..., the nth measurement time t i2 , the third measurement time t i3 ,..., the nth measurement time t in . The plurality of measurement times t i1 , t i2 ,..., t in can be selected according to the acquisition period Δt i .

[0089] Alternatively, the estimated longitudinal acceleration a lon is directly preceded by an available time point that coincides with the time point immediately preceding the unavailable time point when the independent longitudinal reference speed v ref of the railway vehicle is no longer available, and is continuously determined from the measurement instant, for example, the first measurement time t av or the continuous measurement times t i1 ,..., t i2 ,..., t in .

[0090] The present invention also relates to a method for estimating the longitudinal speed of at least one railway vehicle.

[0091] When the estimated longitudinal acceleration a lon is determined for a plurality of measurement times t ref at which the independent longitudinal reference speed v i1 of the railway vehicle is available, and the measurement times are selected according to the acquisition period Δt i2 , t in ,..., t i , a method for estimating the longitudinal speed of at least one railway vehicle is the independent longitudinal reference speed v av of at least one axle of the railway vehicle at the available time point t ref (t avA step of measuring the value of

[0092] Also, a method for estimating the longitudinal speed of at least one railway vehicle includes, according to the following steps, determining the longitudinal speed v of the railway vehicle RV (t in ). - Calculating the sum of the longitudinal accelerations estimated at a plurality of measurement times t i1 , t i2 ,..., t in . - Multiplying the sum of the longitudinal accelerations determined at a plurality of measurement times t i1 , t i2 ,..., t in by the acquisition period Δt i . - Adding the value of the independent longitudinal reference speed V i1 , t i2 ,..., t in of at least one railway vehicle at the available time point t i to the result of multiplying the sum of the estimated longitudinal accelerations determined at a plurality of measurement times t av by the acquisition time Δt ref (t av ).

[0093] For example, the step of determining the longitudinal speed v of the railway vehicle RV can be implemented using the following formula.

Number

Number

[0094] Alternatively, when the estimated longitudinal acceleration a lon is continuously determined directly prior to a time point when the independent longitudinal reference velocity v ref is not available, for example, at a time point t i1 that coincides with the available time point t av , a method for estimating the longitudinal velocity of at least one railway vehicle includes measuring the value of the independent longitudinal reference velocity v av of at least one railway vehicle at the available time point t ref (t av ).

[0095] Also, a method for estimating the longitudinal velocity of at least one railway vehicle includes determining the longitudinal velocity v RV (t) of the railway vehicle according to the following steps. - Calculating the integral of the estimated longitudinal acceleration a av continuously determined from the available time point t i1 to the first measurement time point t lon . - Adding the value of the independent longitudinal reference velocity V av of at least one railway vehicle at the available time point t ref (t av ) to the result of the integral of the estimated longitudinal acceleration.

[0096] For example, the step of determining the longitudinal velocity v RV (t i1 ) of the railway vehicle can be implemented using the following equation.

Equation

Number

[0097] Also, the above is valid for subsequent measurement time points. For example, considering the nth measurement time point t in , the step of determining the longitudinal speed v RV (t in ) of the railway vehicle can be carried out using the following formula.

Number

Number

[0098] Therefore, referring to Figure 5 again, during the period between t ref when the independent longitudinal reference speed v av is not available and t ret_av , it can be summarized that the acceleration of the railway vehicle is calculated from the measured values of the accelerometer.

[0099] Independent longitudinal reference speed v ref when t is not available av and t ret_av During the period between, the speed of the railway vehicle is the measured value from the accelerometer and the last reliable independent longitudinal reference speed value v according to the formula shown above ref is calculated using.

[0100] Advantageously, from what has been described above in this specification, the independent longitudinal reference speed v ref Even when not available, the longitudinal speed v of the railway vehicle RV is always available. For this reason, even in the case of particularly low adhesion, it is possible to completely restore the use of the slipping axles for traction and braking purposes, thus increasing the traction and braking capabilities of the train.

[0101] Various aspects and embodiments of a method for estimating the longitudinal acceleration of at least one railway vehicle according to the present invention and a method for estimating the longitudinal speed of at least one railway vehicle have been described. It should be understood that each embodiment can be combined with any other embodiment. Furthermore, the present invention is not limited to the described embodiments and may be modified within the scope defined by the appended claims.

Claims

1. a first acceleration a along a first axis x ｘ , a second acceleration a along a second axis y ｙ , and a third acceleration a along a third axis z ｚ A method for estimating the longitudinal acceleration of at least one railway vehicle by acceleration sensor means (100) configured to measure, wherein the first axis x, the second axis y and the third axis z are orthogonal to each other, A method for estimating the longitudinal acceleration of at least one railway vehicle comprises - performing a calibration phase including the following steps, ・ At a first calibration time t ｒｅｆ when the independent longitudinal reference speed v of the railway vehicle ｃ１ is available, measuring a first value of a first acceleration a ｘ (t ｃ１ ), a first value of a second acceleration a ｙ (t ｃ１ ), and a first value of a third acceleration a ｚ (t ｃ１ ), where the independent longitudinal reference speed v ｒｅｆ is independent of the acceleration sensor means (100), ・ At a second calibration time t ｒｅｆ when the independent longitudinal reference speed v of the railway vehicle ｃ２ is available, and this second calibration time is different from the first calibration time t ｃ１ , measuring a second value of a first acceleration a ｘ (t ｃ２ ), a second value of a second acceleration a ｙ (t ｃ２ ), and a second value of a third acceleration a ｚ (t ｃ２ ), ・ At a third calibration time t ｒｅｆ when the independent longitudinal reference speed v of the railway vehicle ｃ３ is available, and this third calibration time is different from the first calibration time t ｃ１ and the second calibration time t ｃ２ , measuring a third value of a first acceleration a ｘ (t ｃ３ ), a second acceleration a ｙ (t ｃ３ )'s third value and the third acceleration a ｚ (t ｃ３ )'s third value and measuring steps, ・ At the first calibration time t ｃ１ The independent longitudinal reference speed v available ｒｅｆ (t ｃ１ )'s first value, from the first calibration time t ｃ１ The first independent longitudinal reference acceleration a at ｒｅｆ (t ｃ１ )'s value is calculated steps, ・ At the second calibration time t ｃ２ The effective independent longitudinal reference speed v available ｒｅｆ (t ｃ２ )'s second value, from the second calibration time t ｃ２ The second independent longitudinal reference acceleration a at ｒｅｆ (t ｃ２ )'s value is calculated steps, ・ At the third calibration time t ｃ３ The independent longitudinal reference speed v available ｒｅｆ (t ｃ３ )'s third value, from the third calibration time t ｃ３ The third independent longitudinal reference acceleration a at ｒｅｆ (t ｃ３ )'s value is calculated steps, ・ The first direction cosine k １ , the second direction cosine k ２ And the third direction cosine k ３ To determine the value of, the following system is solved steps, 【Equation 1】 - Following the calibration stage, at least the first measurement time t when the independent longitudinal reference speed of the railway vehicle is not available ｉ１ For, the estimated longitudinal acceleration value a of the at least one railway vehicle ｌｏｎ (t ｉ１ ) is determined, and the estimated longitudinal acceleration value a ｌｏｎ (t ｉ１ ) is for the first measurement time t ｉ１ And is estimated by the following sum. A method including steps. ・The first direction cosine k determined in the calibration phase １ and the first measurement time t ｉ１ at which the first acceleration a ｘ (t ｉ１ ) of the fourth value is multiplied; ・The second direction cosine k determined in the calibration phase ２ and the first measurement time t ｉ１ at which the second acceleration a ｙ (t ｉ１ ) of the fourth value is multiplied; ・The third direction cosine k determined in the calibration phase ３ and the first measurement time t ｉ１ at which the third acceleration a ｚ (t ｉ１ ) of the fourth value is multiplied.

2. A method for estimating the longitudinal acceleration of at least one railway vehicle by acceleration sensor means (100) configured to measure a first acceleration a ｘ along a first axis x, a second acceleration a ｙ along a second axis y, and a third acceleration a ｚ along a third axis z, wherein the first axis x, the second axis y and the third axis z are orthogonal to each other, The method for estimating the longitudinal acceleration of at least one railway vehicle is - performing a calibration phase including the following steps; ・For at least one first calibration time t ｒｅｆ at which the independent longitudinal reference speed v ｃ１ of the railway vehicle is available, the independent longitudinal reference speed v ｒｅｆ is independent of the acceleration sensor means (100), and a linear filter is used to estimate the at least one estimated longitudinal acceleration value a ｌｏｎ (t ｃ１ ), and the estimated longitudinal acceleration value a ｌｏｎ (t ｃ１ ) is for the first calibration time t ｃ１ , and the linear filter estimates by the following sum; The first direction cosine k having a predetermined value １ and the first calibration time point t ｃ１ and the multiplication with the first value of the first acceleration a ｘ (t ｃ１ ) obtained at the time, The second direction cosine k having a predetermined value ２ and the first calibration time point t ｃ１ and the multiplication with the first value of the second acceleration a ｙ (t ｃ１ ) obtained at the time, The third direction cosine k having a predetermined value ３ and the first calibration time point t ｃ１ and the multiplication with the first value of the third acceleration a ｚ (t ｃ１ ) obtained at the time, ・The estimated longitudinal acceleration value a ｃ１ for the first calibration time point t ｌｏｎ (t ｃ１ ) and the first calibration time point t ｃ１ and, for the first calibration time point t ｃ１ the independent reference longitudinal velocity value v ｒｅｆ (t ｃ１ ) available at the time, the reference longitudinal acceleration value a ｒｅｆ (t ｃ１ ) determined from the first value, determining an estimation error (Error) by the difference, ・By the adaptive filter (104), in order to minimize the estimation error, the first direction cosine k imposed on the linear filter １ , the second direction cosine k ２ and the third direction cosine k ３ determining respective updated values of, -Following the calibration phase, for at least a first measurement time point t ｉ１ when the independent longitudinal reference velocity of the railway vehicle is not available, by the linear filter, the estimated longitudinal acceleration value a ｌｏｎ (t ｉ１ ) of the at least one railway vehicle is determined, and the estimated longitudinal acceleration value a ｌｏｎ (t ｉ１)(which is for the first measurement time point ti1) and includes a step estimated by the following sum, method. ・ The updated value of the first direction cosine k determined in the calibration step, １ and the first acceleration a obtained at the first measurement time point t ｉ１ (t ｘ ) of the second value of ｉ１ multiplication, ・ The updated value of the second direction cosine k determined in the calibration step, ２ and the second acceleration a obtained at the first measurement time point t ｉ１ (t ｙ ) of the second value of ｉ１ multiplication, ・ The updated value of the third direction cosine k determined in the calibration step, ３ and the third acceleration a obtained at the first measurement time point t ｉ１ (t ｚ ) of the second value of ｉ１ multiplication.

3. The adaptive filter determines each of the updated values of the first direction cosine k, the second direction cosine k, and the third direction cosine k via an adaptive algorithm based on the least mean squares method, LMS. A method for estimating the longitudinal acceleration of at least one railway vehicle according to claim 2, configured as follows. １ The first direction cosine k, ２ the second direction cosine k, ３ and the third direction cosine k.

4. The calibration step is repeated for a plurality of calibration time points. A method for estimating the longitudinal acceleration of at least one railway vehicle according to any one of claims 1 to 3.

5. The calibration step is performed at each first ignition of the at least one railway vehicle. A method for estimating the longitudinal acceleration of at least one railway vehicle according to any one of claims 1 to 4.

6. The independent longitudinal reference speed v of the railway vehicle ｒｅｆ is the longitudinal speed determined from the angular velocity of the axle of the railway vehicle, The independent longitudinal reference speed v ｒｅｆ A method for estimating the longitudinal acceleration of at least one railway vehicle according to any one of claims 1 to 5, which is available when the axle is not slipping.

7. The independent longitudinal reference speed v of the railway vehicle ｒｅｆ is the longitudinal speed of the railway vehicle provided by the positioning means, The independent longitudinal reference speed v ｒｅｆ A method for estimating the longitudinal acceleration of at least one railway vehicle according to any one of claims 1 to 6, which is available when the positioning means communicates with a satellite.

8. The estimated longitudinal acceleration value a ｌｏｎ is determined for a plurality of measurement times (t ｒｅｆ when the independent longitudinal reference speed v of the railway vehicle is available ｉ１ , t ｉ２ ,..., t ｉｎ ), and the plurality of measurement times (t ｉ１ , t ｉ２ ,..., t ｉｎ ) are selected according to an acquisition period ΔTi. A method for estimating the longitudinal acceleration of at least one railway vehicle according to any one of claims 1 to 7.

9. The estimated longitudinal acceleration value a ｌｏｎ is continuously determined from a available time point t that coincides with the time point immediately preceding the unavailable time point when the independent longitudinal reference speed v of the railway vehicle is no longer available ｒｅｆ and the first measurement time point t ａｖ and the first measurement time point t ｉ１ . A method for estimating the longitudinal acceleration of at least one railway vehicle according to any one of claims 1 to 7.

10. A method for estimating the longitudinal speed of at least one railway vehicle, the method comprising the following steps. - Executing a method for estimating the longitudinal acceleration of at least one railway vehicle according to claim 8, - The independent longitudinal reference speed v of the railway vehicle ｒｅｆ ​​coincides directly with the time point immediately preceding the time point when it is no longer available, the available time point t ａｖ at which the independent longitudinal reference speed V of said at least one railway vehicle ｒｅｆ (t ａｖ ) is measured - the step of determining the longitudinal speed v of the railway vehicle according to the following step ＲＶ (t in), - the step of calculating the sum of the longitudinal accelerations estimated at a plurality of measurement time points (t ｉ１ , t ｉ２ ,..., t ｉｎ ), - the step of multiplying the sum of the longitudinal accelerations determined at a plurality of measurement time points (t ｉ１ , t ｉ２ ,..., t ｉｎ ) by the acquisition period Δt ｉ , - adding the value of the independent longitudinal reference speed V of said at least one railway vehicle at said available time point t ｉ１ , t ｉ２ ,..., t ｉｎ ) to the result of multiplying the sum of said estimated longitudinal accelerations determined at said plurality of measurement time points by said acquisition period Δt ｉ . ａｖ ｒｅｆ ａｖ (t ＲＶ ).

11. The step of determining the longitudinal speed v of said railway vehicle ＲＶ (t ｉｎ ) is performed according to the following formula, a method for estimating the longitudinal speed of at least one railway vehicle according to claim 10 【Equation 2】 Here - v ｒｅｆ (t ａｖ ) is the independent longitudinal reference speed V of said at least one railway vehicle at said available time point t ａｖ (t ｒｅｆ ). ａｖ - the following term 【Equation 3】 is the sum of the longitudinal accelerations determined at the plurality of measurement times t ｉ１ , t ｉ２ ,..., t ｉｎ and n is the number of acquisition periods elapsed between the available time t ａｖ and the measurement time (t ＲＶ (t ｉｎ ) during which the longitudinal velocity v ｉｎ (t -ΔT ｉ is the acquisition period. **Claim 12** A method for estimating the longitudinal velocity of at least one railway vehicle, the method comprising the following steps - Executing a method for estimating the longitudinal acceleration of at least one railway vehicle according to claim 9 - Measuring the value of the independent longitudinal reference velocity V ｒｅｆ (t ａｖ ) of the at least one railway vehicle at the available time t ａｖ - Determining the longitudinal velocity v ＲＶ (t ｉ１ ) of the railway vehicle according to the following steps - Calculating the integral of the estimated longitudinal acceleration a ａｖ continuously determined from the available time t ｉ１ to the first measurement time t ｌｏｎ - Adding the value of the independent longitudinal reference velocity V ａｖ of the at least one railway vehicle at the available time t ｒｅｆ (t ａｖ ) to the result of the integral of the estimated longitudinal acceleration. **Claim 13** The step of determining the longitudinal velocity v ＲＶ (t ｉ１ ) of the railway vehicle is performed according to the following formula, a method for estimating the longitudinal velocity of at least one railway vehicle according to claim 12 **Equation 4** where - v ｒｅｆ (t​​ ａｖ is the independent longitudinal reference speed V ａｖ at the available time point t ｒｅｆ (t ａｖ ). - Next item: 【Number 5】 is the integral of the estimated longitudinal acceleration a ａｖ continuously determined from the available time point t ＲＶ (t ｉ１ ) until the first measurement time point t ｉ１ during which the longitudinal speed v ｌｏｎ (t

14. The first measurement time point t ｉ１ is the available time point t ｒｅｆ at which the independent longitudinal reference speed V ｒｅｔ＿ａｖ becomes available again after becoming unavailable, and is a method for estimating the longitudinal speed of at least one railway vehicle according to any one of claims 10 to 13 that coincides with the return to t

Images