Railway vehicle system, acceleration measurement method for railway vehicle, and vehicle acceleration correction method

Abstract

To provide a setup in which an accelerometer is permanently installed on a running railway vehicle and establish an environment in which data from the accelerometer can be used to ascertain vehicle behavior, a railway vehicle system according to the present invention incorporates an accelerometer into an equipment device box that is installed on a railway vehicle, and the accelerometer measures the acceleration in the directions of an x axis that is parallel to the advancement direction of the railway vehicle and at least one of a y axis that is parallel to a floor surface of the railway vehicle and perpendicular to the advancement direction of the railway vehicle and a z axis that is perpendicular to the floor surface of the railway vehicle.

Description

Railway vehicle system, method for measuring acceleration in railway vehicle, and method for correcting vehicle acceleration

[0001] The present invention relates to a railway vehicle system in which an accelerometer is mounted on a vehicle, an acceleration measurement method for a railway vehicle, and a vehicle acceleration correction method.

[0002] In railway vehicles, vehicle acceleration is essential data to measure when conducting vehicle performance tests, etc. When installing an accelerometer on a railway vehicle, the detection signal from the acceleration sensor is subjected to necessary processing such as signal amplification via an amplifier, and the data is transmitted to the required equipment, etc., and also stored.

[0003] Patent Document 1 describes a technology that calculates a gradient value using an acceleration sensor in the train's direction of travel and an acceleration sensor in the vertical direction, corrects this calculated gradient value taking into account upper and lower gradient limits and the train position, and generates powering commands and braking commands based on this corrected gradient value.

[0004] Japanese Patent Application Laid-Open No. 2023-141304

[0005] As mentioned above, although vehicle acceleration is essential data to be measured during performance testing, there is no established system for continuously measuring vehicle acceleration after receiving railway vehicles from the vehicle manufacturer.

[0006] Furthermore, when installing an accelerometer on a railway vehicle, in addition to the acceleration sensor, the amplifier mentioned above, a means for transmitting or storing data, etc. are separately required, which poses many constraints, such as the need to discuss with the vehicle manufacturer.

[0007] However, if accelerometers can be permanently installed on railway vehicles, the benefits of installing them would be great, as they could be used to change parameters to improve the stability of inverter control.

[0008] In Patent Document 1, acceleration sensors are installed in the direction of train travel and in the vertical direction, and gradient values ​​are calculated using the outputs of each sensor. However, there is no mention of using a three-axis accelerometer installed away from the center of rotation of the vehicle to understand vehicle behavior, including estimating the rotational acceleration around each axis of the railway vehicle, or of correcting acceleration data obtained from the accelerometer using gradient data according to the running position to calculate vehicle acceleration.

[0009] Therefore, the present invention aims to establish a system in which accelerometers are permanently installed in operating railway vehicles, and to establish an environment in which vehicle behavior can be understood by utilizing data obtained from these accelerometers.

[0010] In order to solve the above problems, one representative railway vehicle system according to the present invention has an X-axis that is parallel to the direction of travel of the railway vehicle, a Y-axis that is parallel to the floor of the railway vehicle and perpendicular to the direction of travel of the railway vehicle, and a Z-axis that is perpendicular to the floor of the railway vehicle, and the equipment box mounted on the railway vehicle has an accelerometer built in that measures acceleration in at least two of the three axes, including the X-axis.

[0011] According to the present invention, it is possible to grasp the vehicle behavior from the measured acceleration, quantify the ride comfort and track irregularity, and predict the tendency for abnormality to occur. Problems, configurations, and effects other than those described above will become clear from the description of the following embodiments of the invention.

[0012] FIG. 1 is a diagram showing an example of installation when an accelerometer is implemented in a railway vehicle system according to the present invention. FIG. 2 is a block diagram showing one aspect of accelerometer detection value processing as embodiment 1 of a railway vehicle system according to the present invention. FIG. 3 is a diagram showing an example of track irregularity in the vertical direction relative to the direction of travel of the vehicle. FIG. 4 is a block diagram showing one aspect of accelerometer detection value processing as embodiment 2 of a railway vehicle system according to the present invention. FIG. 5 is a block diagram showing one aspect of vehicle acceleration correction processing as embodiment 3 of a railway vehicle system according to the present invention. FIG. 6 is a diagram showing an aspect of vehicle acceleration correction calculation in scene A. FIG. 7 is a diagram showing an aspect of vehicle acceleration correction calculation in scene B. FIG. 8 is a diagram showing an aspect of vehicle acceleration correction calculation in scene C. FIG. 9 is a block diagram showing an example of the configuration of a PWM inverter drive control system for an induction motor including a vehicle acceleration correction calculation unit. FIG. 10 is a block diagram showing an example of the detailed configuration of the gradient calculation unit shown in FIG. 5. FIG. 11 is a diagram showing an example of a station location information database and a gradient information database, and an example of the relationship between station location and altitude according to kilometre distance.

[0013] Hereinafter, with reference to the drawings, a first to third embodiments of the present invention will be described. Note that the present invention is not limited to these embodiments. In addition, in the drawings, the same parts are denoted by the same reference numerals.

[0014] 1 is a diagram showing an example of installation when an accelerometer is implemented in a railway vehicle system according to the present invention. A vehicle 1 is shown in three views, and the front view shows a bogie 11 with wheels 12 and an equipment box 13 installed under the floor. The side view showing the side to the right of the two-dot chain line in the front view also shows the equipment box 13, as well as the bogie 11 and wheels 12 (dotted lines). The plan view also shows the equipment box 13 (dotted lines).

[0015] Various devices such as an inverter device and a controller (logic unit) are housed inside the device box 13, and an accelerometer 15 (hatched with diagonal lines) is also mounted therein. For example, as shown in the speech bubble at the bottom right of Fig. 1, the accelerometer is installed as shown on a circuit board constituting the controller (logic unit) unit 14 housed inside the device box 13. For example, if the controller (logic unit) unit 14 is assumed to be accessible from the side under the floor, the acceleration (X-axis) direction will be perpendicular to the board surface of at least one circuit board of the controller (logic unit) unit 14.

[0016] As described above, by mounting an accelerometer on the circuit board of a control device such as a controller unit installed inside the device box, it is possible to solve the issues that arise in the measurement environment, such as the need to secure a power source, install an amplifier, and install separate equipment for converting and storing measurement data.

[0017] Each of the three views shows the three axes of X, Y, and Z and the central axis of rotation of the vehicle for each axis. ２ / dt ２ ), and the acceleration components (d ２ / dt ２ ) is written.

[0018] The accelerometer 15 is installed in the equipment box 13 at a distance Lx from the center of rotation of the vehicle in the X-axis direction, Ly in the Y-axis direction, and Lz in the Z-axis direction. This allows the acceleration measurements by the accelerometer 15 to estimate (measure) not only the acceleration in the three X-, Y-, and Z-axis directions, but also the rotational acceleration around each axis. However, the measurements of the triaxial accelerometer alone cannot distinguish between the X-axis direction and the Y-axis rotation, the Y-axis direction and the Z-axis rotation, or the Z-axis direction and the X-axis rotation. Therefore, by introducing the dynamic characteristics of the railway vehicle and assigning a natural frequency (operating mode) to each degree of freedom, the measurements of the triaxial accelerometer can be separated into the acceleration values ​​for each axis and each axis rotation.

[0019] Acceleration of each axis rotation ((d ２ / dt２ ) φ, (d ２ / dt ２ ) θ, (d ２ / dt ２ Specifically, it is possible to measure irregularities in the vehicle's behavior caused by the X-axis rotation (φ) to detect irregularities in the left and right rail height (see side view), the Y-axis rotation (θ) to detect irregularities in the track above and below the direction of travel (see front view), and the Z-axis rotation (ψ) to detect irregularities in the track to the left and right of the direction of travel (see top view).

[0020] In the present invention, in order to measure the presence or absence of track irregularities as described above and to measure the riding comfort of the vehicle, acceleration is measured in at least two directions of the three axes X, Y, and Z, including the X-axis direction parallel to the direction of vehicle travel.

[0021] The vehicle 1 equipped with the device box 13 in which the accelerometer 15 is installed is not limited to a powered vehicle equipped with a drive motor. The device box 13 may also be installed in a trailer vehicle (a vehicle without a power source) adjacent to the powered vehicle. The type of acceleration sensor used for the accelerometer 15 is not particularly limited, but it is necessary that the sensor be capable of acquiring signals from at least 0 to 20 Hz.

[0022] 2 is a block diagram showing one mode of accelerometer detection value processing as a first embodiment of the railway vehicle system according to the present invention. In the first embodiment, a processing mode is shown in which detected acceleration values ​​in each of the three axes X, Y, and Z and estimated rotational acceleration values ​​for each axis are calculated based on detected acceleration values ​​for each of the three axes X, Y, and Z detected as sensor outputs from the accelerometer 15 shown in FIG. 1 , and input to the acceleration tolerance value determination unit 16.

[0023] The sensor outputs for each of the three axes X, Y, and Z from the accelerometer 15, namely, the acceleration detection value (X axis) ACCx0, the acceleration detection value (Y axis) ACCy0, and the acceleration detection value (Z axis) ACCz0, are passed through a low-pass filter and an offset compensation circuit, and are output as the acceleration detection value (X axis) ACCx, the acceleration detection value (Y axis) ACCy, and the acceleration detection value (Z axis) ACCz, respectively. The offset compensation circuit is provided to remove the zero frequency component.

[0024] The detected acceleration value (X-axis) ACCx0, the detected acceleration value (Y-axis) ACCy0, and the detected acceleration value (Z-axis) ACCz0 are each passed through a bandpass filter and output as an estimated acceleration value (Y-axis rotation) ACCθ, an estimated acceleration value (Z-axis rotation) ACCψ, and an estimated acceleration value (X-axis rotation) ACCφ. In other words, the rotational acceleration of each axis is estimated using a frequency band.

[0025] The acceleration tolerance determination unit 16 receives the acceleration detection values ​​for each of the three axes and the acceleration estimation values ​​related to the axial rotation (rotational acceleration estimation values), compares them with a determination model related to ride comfort or track irregularity, and determines whether each detection value or estimation value is within a normal range. This makes it possible to estimate the three-dimensional behavior of the vehicle 1 and identify any abnormal states. Furthermore, if necessary, the determination results and extraction results may be output to a predetermined display means, or may be stored or displayed on the ground via a data transmission means (not shown).

[0026] For example, the occurrence of fluctuations due to track irregularities will be explained using FIG. 3. FIG. 3 is a diagram showing an example of track irregularities in the vertical direction relative to the direction of travel of the vehicle. When track irregularities exist in the vertical direction relative to the direction of travel of the vehicle 1, they appear as fluctuations (pitching) in the Y-axis rotation (θ) according to the position. That is, as shown in the graph on the right side of FIG. 3, the vertical deviation on the track causes the Y-axis rotation acceleration (d ２ / dt ２ ) θ varies depending on the travel position.

[0027] As described above, according to the first embodiment, the acceleration detection values ​​of the three axes X, Y, and Z and the rotational acceleration around each of the three axes can be estimated by the accelerometer installed in the device box. This makes it possible to grasp the vehicle behavior (three-dimensional behavior) and quantify the ride comfort, track irregularity, etc.

[0028] 4 is a block diagram showing one mode of accelerometer detection value processing as a second embodiment of a railway vehicle system according to the present invention. In the second embodiment, a processing mode is used in which acceleration detection values ​​and rotational acceleration estimates are calculated using on-board and ground-side devices, with the on-board devices specializing in acceleration detection, and the ground-side devices storing data and reproducing vehicle behavior.

[0029] The acceleration detection value (X-axis) ACCx0, the acceleration detection value (Y-axis) ACCy0, and the acceleration detection value (Z-axis) ACCz0, which are sensor outputs for the three axes X, Y, and Z from the accelerometer 15 shown in FIG. 1 on the vehicle side, are transmitted to the ground via data transmission by wireless communication after passing through a low-pass filter and an offset compensation circuit. Note that the low-pass filter is used to narrow the frequency band assuming data transmission at a 20 ms interval. Similarly to FIG. 2, the offset compensation circuit is used to remove zero-frequency components.

[0030] The sensor outputs for each of the three axes, X, Y, and Z, transmitted as data from on-board are received by specified equipment on the ground, and a digital twin model 17 provided on the ground is used to calculate the acceleration detection value (X-axis) ACCx, acceleration detection value (Y-axis) ACCy, acceleration detection value (Z-axis) ACCz, as well as the acceleration estimate value (Y-axis rotation) ACCθ, acceleration estimate value (Z-axis rotation) ACCψ, and acceleration estimate value (X-axis rotation) ACCφ, and both values ​​are input together to the acceleration tolerance value determination unit 16.

[0031] Here, the sensor outputs for each of the three axes received by a predetermined device on the ground may be accumulated in a data storage unit (not shown) provided on the ground, read from the data storage unit, and input to the digital twin model 17. Furthermore, the detected acceleration values ​​and estimated rotational acceleration values ​​for each of the three axes, X, Y, and Z, calculated by the digital twin model 17 may be stored in the data storage unit.

[0032] By using technologies such as IoT, AI, and AR, the digital twin model 17 has the function of enabling each physical quantity to be output by performing the same movement (identification) when vibrating the vehicle model at the same position as the acceleration measurement point of the actual vehicle.

[0033] 2, the acceleration tolerance determination unit 16 receives the acceleration detection values ​​of the three axes and the acceleration estimation values ​​related to the axis rotation, compares them with a determination model related to ride comfort or track irregularity, and determines whether the detected values ​​and the estimated values ​​are within a normal range. In addition, it becomes possible to extract an abnormal state of the vehicle from the determination result.

[0034] Furthermore, in the second embodiment, the data relating to the acceleration is accumulated on the ground, so that it becomes possible to predict the tendency of abnormalities occurring over time.

[0035] 5 is a block diagram showing one aspect of the vehicle acceleration correction process as a third embodiment of the railway vehicle system according to the present invention. In the third embodiment, the vehicle acceleration is calculated by correcting accelerometer data based on gradient data (route information).

[0036] Vehicle acceleration is calculated based on the sensor output from the accelerometer 15 installed in the controller (logic unit) unit 14 shown in FIG. 1. However, in some situations, the desired vehicle acceleration (acceleration in the traveling direction (X-axis)) cannot be calculated correctly, and therefore a correction calculation is required depending on the situation. Specifically, this is the case when the vehicle is on a gradient section. The gradient calculation unit 21, calculators 22 and 23, and vehicle acceleration correction unit 24 shown in FIG. 5 are components of a vehicle acceleration correction calculation unit 9 shown in FIG. 9, which will be described later.

[0037] The gradient calculation unit 21 receives the GPS point data GP, the station position information database (DB STN), the gradient information database (DB GRD), and the vehicle speed VEL as inputs, and calculates the gradient of the vehicle travel point.

[0038] Based on the calculated gradient, the X-axis component and Y-axis component of the gravitational acceleration (g) are calculated by calculator 22 (g sin θ) and calculator 23 (g cos θ), and the results of these calculations are subtracted from the acceleration detection value (X-axis) ACCx in the vehicle traveling direction and the acceleration detection value (Z-axis) ACCz in the direction perpendicular to the vehicle, both of which are obtained by accelerometer 15, to correct the acceleration detection values ​​based on the gradient.

[0039] The vehicle acceleration correction unit 24 calculates the corrected vehicle acceleration αvx taking into consideration the gradient-corrected X-axis and Z-axis acceleration detection values ​​ACCx and ACCz, the driving command (notch) NTC, the pulling force F, and the train mass M.

[0040] Next, the situations where the above-mentioned correction calculation is required will be described. Specifically, three situations in a gradient section are designated as situation A, situation B, and situation C. The following (1) to (3) illustrate the manner of vehicle acceleration correction calculation for each of these situations using Figures 6 to 8. Note that the vehicle acceleration αx calculated in the following situations A, B, and C is αvx calculated and output by the vehicle acceleration correction unit 24 shown in Figure 5 (αx = αvx). Furthermore, unlike Figure 1, the coordinate axes shown in situations A, B, and C in Figures 6 to 8 have the y-axis perpendicular to the vehicle.

[0041] (1) Scene A (Vehicle Stopped on a Gradient Section) Figure 6 is a diagram showing the manner of vehicle acceleration correction calculation in scene A. Scene A is a scene in which the vehicle is stopped on a gradient section. Since the vehicle is stopped, the driving command (notch) NTC is 0 (Off), and the tractive force F, i.e., the braking force (M g sin θ), is equal to M αx + M g sin θ, where αx is the vehicle acceleration. That is, αx + g sin θ = g sin θ. Meanwhile, the detected acceleration value ACCx of the X-axis is equal to αx + g sin θ. That is, ACCx = αx + g sin θ = g sin θ. Then, the vehicle acceleration αx = ACCx - g sin θ = 0.

[0042] (2) Scene B (Coasting on a gradient section) Figure 7 is a diagram showing the manner of vehicle acceleration correction calculation in scene B. Scene B is a scene in which the vehicle is coasting on a gradient section (driving with the brakes released). Because the vehicle is coasting, the driving command (notch) NTC is 0 (Off) and the tractive force F is also 0, so M αx + M g sin θ = F = 0. Meanwhile, the detected acceleration value ACCx on the X-axis is equal to αx + g sin θ. That is, ACCx = αx + g sin θ. Then, vehicle acceleration αx = ACCx - g sin θ.

[0043] (3) Scene C (powering (braking) on ​​a gradient section) Figure 8 is a diagram showing the manner of vehicle acceleration correction calculation in scene C. Scene C is a scene in which the vehicle is powering (braking) on ​​a gradient section. Because it is in a powering (braking) state, the driving command (notch) NTC is not 0, and the tractive force F is equal to M x αx + M x g x sin θ, so αx + g x sin θ = F / M. On the other hand, the detected acceleration value ACCx on the X-axis is equal to αx + g x sin θ. In other words, ACCx = αx + g x sin θ = F / M. This gives the following vehicle acceleration αx = ACCx - g x sin θ = F / M - g x sin θ.

[0044] As described above, the vehicle acceleration αx is corrected by the vehicle acceleration correcting unit 24 depending on the situation (condition) of the gradient section, and is output as a corrected vehicle acceleration αvx.

[0045] Next, a drive system that makes it possible to change inverter control parameters based on corrected vehicle acceleration will be described. Fig. 9 is a block diagram showing an example of the configuration of a PWM inverter drive control system for an induction motor that includes a vehicle acceleration correction calculation unit.

[0046] The PWM inverter 4 converts DC power from the overhead line via the pantograph 10 into variable voltage / variable frequency (VVVF) AC power and supplies it to a plurality of induction motors 7 to drive these induction motors 7. Inverter drive control for this PWM inverter 4 is based on speed sensorless vector control, and this control is executed by the vector control calculation unit 5. In this embodiment, the power supplied from the overhead line 10 is DC power, but in the case of AC power, the present invention can be applied by providing a PWM converter that converts AC power to DC power in the upstream stage (DC input side) of the PWM inverter 4.

[0047] The vector control calculation unit 5 receives the d-axis current command Idp and the q-axis current command Iqa from the current command calculation unit 3 and the speed estimation value Frh from the speed estimation calculation unit 8, and executes vector control by taking in the detected currents iu to iw of the three-phase motor currents from the current detectors 6a to 6c. Note that by providing two of the current detectors, i.e., current detector 6a and its detected current iu, current detector 6b and its detected current iv, and current detector 6c and its detected current iw, and obtaining the detected currents, the detected currents to be detected by the current detectors can be calculated using the following equations without providing another current detector: iu = iv - iw iv = iw - iu iw = iu - iv In other words, by providing at least two of the current detectors 6a, 6b, and 6c, it is possible to execute vector control by taking in the detected currents iu to iw.

[0048] The current command calculation unit 3 receives a driving command (notch) NTC from a driver's cab 2 mounted on the vehicle 1, and generates the d-axis current command Idp and the q-axis current command Iqa.

[0049] The vehicle acceleration correction calculation unit 9 has the configuration shown in FIG. 5 , and receives as inputs the operation command (notch) NTC, the acceleration detection value (X-axis) ACCx, the acceleration detection value (Y-axis) ACCy, the GPS point data GP, the station position information database (DB STN), the gradient information database (DB GRD), the vehicle speed VEL, the pulling force F, and the train set mass M, and outputs a corrected vehicle acceleration αvx corresponding to these inputs to the speed estimation calculation unit 8.

[0050] The speed estimation calculation unit 8 receives the corrected vehicle acceleration αvx from the vehicle acceleration correction calculation unit 9 and the acceleration estimation value input Acch from the vector control calculation unit 5 as inputs, and calculates the speed estimation value Frh based on these.

[0051] According to the inverter drive control of the third embodiment described above, the control can be optimized by improving the calculation performance of the acceleration estimate based on the corrected vehicle acceleration, and stable control performance can be expected to be achieved.

[0052] 10 is a block diagram showing an example of a detailed configuration of the gradient calculation unit 21 shown in FIG. The stop station determination unit 25 receives the GPS point data GP, the station location information database (DB STN), and the vehicle speed VEL as input. When the vehicle speed VEL is zero, the stop station determination unit 25 searches the station location information database (DB STN) for station information within a range of, for example, 200 m (20 m / car × 10 cars ≒ platform length) from the GPS point data GP. If a hit is found, the stop station determination unit 25 determines that the train is currently stopped at that station and outputs the stop station location (kilometers) and stop station number. Furthermore, until a new stop determination is made, the stop station determination unit 25 continues to output the stop station location (kilometers) and stop station number from which the train was previously determined to be stopped.

[0053] When the vehicle speed VEL is not zero and the train starts running, the integrator (1 / S) 27, which has been reset by the output from the edge detector 26 in response to the input of the stop station number, integrates the signed vehicle speed VEL and adds it to the stop station position (kilometers) to calculate the running kilometers. Also, if a train control management system (TCMS) is operating, the running position of the vehicle may be obtained directly from the TCMS.

[0054] The gradient amount reference unit 28 receives the traveled kilometer and the gradient information database (DB GRD) as input, searches the gradient information database (DB GRD) based on the traveled kilometer, and outputs the gradient amount at the traveled position.

[0055] FIG. 11 is a diagram showing an example of a station location information database (DB STN) and a gradient information database (DB GRD), as well as an example of the relationship between station locations and altitudes according to kilometres.

[0056] The station location information database (DB STN) stores at least station numbers, station names, station location kilometers, and station location point information as a database. In the example shown in FIG. 11, the station location point information is represented by latitude and longitude.

[0057] On the other hand, the gradient information database (DB GRD) stores at least the kilometers of the gradient start point and gradient end point, and the gradient amount (‰, where 1‰=0.1%) between the start point and the end point.

[0058] Based on these two databases, the relationship between station location and altitude according to kilometer distance is shown in the upper part of Figure 11. Stations L, M, N, and O are located at kilometer distances P0, P5, P10, and P13, and the gradient start and end points (P0 to P13) between Stations L and O, as well as the gradient amounts (G1 to G11) between them, can be obtained.

[0059] Although the first to third embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the present invention.

[0060] 1...vehicle, 2...driver's cab, 3...current command calculation unit, 4...PWM inverter, 5...vector control calculation unit, 6a, 6b, 6c...current detector, 7...induction motor, 8...speed estimation calculation unit, 9...vehicle acceleration correction calculation unit, 10...pantograph, 11...bogie, 12...wheel, 13...device box, 14...controller (logic unit) unit, 15...accelerometer, 16...acceleration tolerance determination unit, 17...digital twin model, 21...gradient calculation unit, 22, 23...calculator, 24...vehicle acceleration correction unit, 25...stop station determination unit, 26...edge detector, 27...integrator, 28...gradient amount reference unit

Claims

1. A railway vehicle system in which an axis parallel to the direction of travel of the railway vehicle is defined as the X-axis, an axis parallel to the floor of the railway vehicle and perpendicular to the direction of travel of the railway vehicle is defined as the Y-axis, and an axis perpendicular to the floor of the railway vehicle is defined as the Z-axis, and an equipment box mounted on the railway vehicle has an accelerometer built in, and the accelerometer measures acceleration in at least two of the three axes, including the X-axis.

2. A railway vehicle system as described in claim 1, wherein the equipment box incorporates a controller unit that controls the operation of equipment mounted on the railway vehicle, and the accelerometer is installed on at least one of the circuit boards that make up the controller unit.

3. A railway vehicle system according to claim 1 or 2, wherein the accelerometer is installed at a position that does not intersect with any of the centers of rotation of the X-axis, the Y-axis, and the Z-axis, and measures acceleration in the direction of the Y-axis and the Z-axis in addition to the direction of the X-axis.

4. A railway vehicle system according to claim 3, wherein rotational accelerations about the X-axis, the Y-axis and the Z-axis are estimated based on the accelerations in the X-axis direction, the Y-axis direction and the Z-axis direction measured by the accelerometer, as well as the dynamic characteristics of the railway vehicle.

5. A railway vehicle system as claimed in claim 4, wherein the accelerations measured by the accelerometer in the X-axis direction, the Y-axis direction and the Z-axis direction are transmitted to a ground-side device via wireless communication, and the ground-side device estimates the rotational acceleration around each of the axes.

6. A railway vehicle system according to any one of claims 1 to 5, characterized in that the vehicle acceleration of the railway vehicle is corrected to a vehicle acceleration based on the track surface on which the railway vehicle is traveling, based on the accelerations in the X-axis direction, the Y-axis direction and the Z-axis direction measured by the accelerometer, and the gradient amount of the traveling point of the railway vehicle obtained by referencing track gradient data that records the gradient amount of the section on which the railway vehicle is traveling from the traveling point information of the railway vehicle.

7. A railway vehicle system as claimed in claim 6, characterized in that when torque control of the electric motor for driving the vehicle mounted on said railway vehicle is performed using a speed estimate value, said speed estimate value is calculated using said corrected vehicle acceleration when starting from a stop on a gradient section at said running point or when driving on said gradient section.

8. A method for measuring acceleration in a railway vehicle, characterized in that an axis parallel to the direction of travel of the railway vehicle is defined as the X-axis, an axis parallel to the floor of the railway vehicle and perpendicular to the direction of travel of the railway vehicle is defined as the Y-axis, and an axis perpendicular to the floor of the railway vehicle is defined as the Z-axis, and an accelerometer is installed in an equipment box mounted on the railway vehicle to measure acceleration in at least two of the three axes, including the X-axis.

9. A method for measuring acceleration in a railway vehicle as set forth in claim 8, characterized in that the accelerometer is installed at a position that does not intersect with the center of rotation of any of the X-axis, Y-axis, and Z-axis, and measures acceleration in the direction of the Y-axis and the Z-axis in addition to the direction of the X-axis.

10. A method for measuring acceleration in a railway vehicle as claimed in claim 9, characterized in that rotational accelerations about the X-axis, Y-axis and Z-axis are estimated based on the accelerations in the X-axis direction, Y-axis direction and Z-axis direction measured by the accelerometer and the dynamic characteristics of the railway vehicle.

11. A vehicle acceleration correction method using acceleration measurements in a railway vehicle as set forth in claim 9, characterized in that the vehicle acceleration of the railway vehicle is corrected to a vehicle acceleration based on the track surface on which the railway vehicle is traveling, based on the accelerations in the X-axis direction, the Y-axis direction, and the Z-axis direction measured by the accelerometer, and the gradient amount of the running point of the railway vehicle obtained by referencing track gradient data that records the gradient amount of the section on which the railway vehicle is traveling from the running point information of the railway vehicle.

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