Measuring device and measuring method

Abstract

To provide a measuring device and method that improve the accuracy of measuring lateral pressure and the like.SOLUTION: This is a measuring device for measuring the lateral force Q or contact position between the wheels and rails of a railway vehicle. The measuring device comprises a plurality of strain gauges arranged around the central axis of rotation of the wheel to detect shear strain in the plate portion caused by the lateral force, and a calculation unit that calculates the lateral force, etc. based on the output of a bridge circuit composed of strain gauges and asymmetric with respect to the axis of rotation. The calculation unit 200 calculates the lateral force or contact position by calculating a second offset amount based on an output model of the bridge circuit generated based on the relationship between the wheel load, lateral force, and longitudinal tangential force acting between the wheel and rail obtained in a static load test and the output of the bridge circuit, the model including a first offset term caused by the sensitivity characteristics of the bridge circuit that change with wheel rotation, and a second offset term caused by a cause other than the sensitivity characteristics that change with wheel rotation.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a measuring device and a measuring method, and more particularly to a device and a method for measuring wheel lateral force, contact position, etc. [Background technology]

[0002] To evaluate the running safety of railway vehicles, a method is known for measuring the contact force between the wheel and rail using a special wheelset called a PQ wheelset, which has a large number of strain gauges attached to the wheel.If this method can measure the contact position between the wheel and rail in the sleeper direction in addition to the contact force, it may be possible to contribute to elucidating the phenomenon related to wheel-rail contact and to establishing a more in-depth running safety evaluation. Furthermore, with conventional PQ wheelsets, errors occur in the lateral force measurement results depending on the magnitude of the wheel load and the amount of shift in the lateral contact position, but if the contact position can be measured, this error can be corrected.

[0003] Against this background, methods have been proposed to measure the contact position by attaching strain gauges for contact position measurement to the PQ wheelset (Non-Patent Documents 1, 2, and 3). In addition, a method has been proposed in which contact position information is extracted based on changes in frequency characteristics by using multiple lateral force measurement bridge circuits in combination (Non-Patent Document 4). Furthermore, as a related technology, a method has been proposed that uses hardware equivalent to that of conventional PQ wheelsets, but corrects some of the errors that occur in the lateral force measurement results (Non-Patent Document 5). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Kanehara, Ohno. "Development of a continuous measurement device for wheel-rail contact position to clarify derailment mechanism," JR EAST Technical Review No.3 [Non-patent document 2] Ozawa, et al., "Method for identifying contact position between wheel and rail using strain analysis of wheel disc," J-RAIL2018, No. 3211, 2018. [Non-patent document 3] Noguchi, "Study on measurement method of wheel / rail contact position," J-RAIL2019, No. S6-1-4, 2019. [Non-patent document 4] Hondo, et al., "Contact position information extraction processing method based on frequency analysis of PQ wheelsets utilizing bending and shear strains," Transactions of the Japan Society of Mechanical Engineers, DOI: 10.1299 / transjsme.22-00128, 2022. [Non-Patent Document 5] Hondo, et al., "A correction method for wheel-rail lateral force measurement data based on the lower limit estimation of the load center position," Dynamics & Design Conference 2022, Paper No. 515, 2022. Summary of the Invention [Problem to be solved by the invention]

[0005] The methods described in Non-Patent Documents 1, 2, and 3 require the strain gauge for measuring force and the strain gauge for measuring contact position to be attached separately, which poses the problem of the large amount of labor required to manufacture the PQ wheelset. Furthermore, the method of Non-Patent Document 4 has a problem in that it has low sensitivity to the contact position, and the contact position information that can be acquired is an average value over one rotation of the wheel, resulting in a loss of dynamic information. Furthermore, the method of Non-Patent Document 5 is a method that focuses only on "correcting the measurement error of lateral force" among the effects of contact position measurement described in the background art, and is not able to obtain the contact position itself.

[0006] The present invention provides a measuring device and a measuring method that improve the accuracy of measuring lateral pressure or contact position. [Means for solving the problem]

[0007] In order to solve the above problems, a measuring device according to a first aspect of the present invention is a measuring device for measuring the lateral force or contact position between a wheel of a railway vehicle and a rail, the wheel having a rim portion on the outer periphery on which a tread is formed, a boss portion in the center to which an axle is attached, and a plate portion provided between the rim portion and the boss portion, the measuring device comprising a plurality of strain gauges which penetrate the plate portion in the direction of the central axis of rotation of the wheel and are attached to the inner surfaces of holes arranged around the central axis of rotation to detect shear strain in the plate portion due to lateral force, and a bridge circuit made up of the strain gauges, and the measuring device is able to determine the lateral force or contact position between the wheel and a rail based on the output of the bridge circuit which is asymmetric with respect to the central axis of rotation. and a calculation unit that calculates the lateral force or contact position, the calculation unit comprising: an offset calculation unit that calculates a second offset amount based on an output model of the bridge circuit, the second offset amount being generated based on the relationship between the wheel load, lateral force, and longitudinal tangential force acting between the wheel and rail obtained in a static load test and the output of the bridge circuit, the model including a first offset term caused by the sensitivity characteristics of the bridge circuit that change with wheel rotation, and a second offset term caused by a cause other than the sensitivity characteristics that change with wheel rotation; and a measurement value calculation unit that calculates the lateral force or contact position by removing the second offset amount from the output of the bridge circuit.

[0008] A second aspect of the present invention provides a measuring method for measuring lateral force or contact position between a wheel and a rail of a railway vehicle, in which the wheel has a rim portion on its outer periphery where a tread is formed, a boss portion in the center to which an axle is attached, and a plate portion located between the rim portion and the boss portion. The measuring method comprises attaching a plurality of strain gauges to the inner surfaces of holes that penetrate the plate portion in the direction of the wheel's central axis of rotation and are arranged around the central axis of rotation, and detecting shear strain in the plate portion due to lateral force; an offset calculation unit calculates a second offset amount based on an output model of the bridge circuit, which is generated based on the relationship between the wheel load, lateral force, and longitudinal tangential force acting between the wheel and rail obtained in a static load test and the output of the bridge circuit, the model including a first offset term caused by the sensitivity characteristics of the bridge circuit that change with wheel rotation and a second offset term caused by a cause other than the sensitivity characteristics that change with wheel rotation; and a measurement value calculation unit calculates the lateral force or contact position by removing the second offset amount from the output of the bridge circuit. [Effects of the Invention]

[0009] According to the present invention, in signal processing obtained from an axially asymmetric bridge circuit in a PQ axle that utilizes shear strain, the offset amount is calculated using an output model of the bridge circuit that includes an offset term constructed from the static load test results, thereby enabling high-precision calculation of lateral force and contact position with the offset removed. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the configuration of a wheel and the arrangement of strain gauges used in a lateral force measuring device or the like according to an embodiment. [Figure 2] FIG. 2 is a diagram showing the arrangement of only the strain gauges required to configure an axisymmetric bridge circuit, among the strain gauges shown in FIG. [Figure 3] FIG. 3 shows the basic form of an axially asymmetric bridge circuit for the lateral pressure measurement method utilizing shear strain. [Figure 4]Figure 4 shows a bridge circuit using adjacent strain gauges in a lateral pressure measurement method that utilizes shear strain. [Figure 5] Figure 5 shows an axially asymmetric bridge circuit using bending strain. [Figure 6] FIG. 6 is a schematic diagram illustrating signal processing for offset removal in an axisymmetric bridge circuit. [Figure 7] FIG. 7 is a schematic diagram illustrating signal processing when a high-pass filter is applied to an axially asymmetric bridge circuit. [Figure 8] FIG. 8 is a schematic diagram illustrating signal processing by offset calculation according to this embodiment in an axially asymmetric bridge circuit. [Figure 9] FIG. 9 is a block diagram for performing offset cancellation for PQ measurements. [Figure 10] FIG. 10 is a flowchart for calculating the offset amount. [Figure 11] FIG. 11 is a diagram showing the sensitivity and cross sensitivity characteristics of the bridge circuit for measuring wheel load in the static load test results, and is a diagram showing wheel load sensitivity. [Figure 12] FIG. 12 is a diagram showing the sensitivity and cross sensitivity characteristics of the bridge circuit for measuring wheel load in the static load test results, and is a diagram showing the cross sensitivity to lateral force. [Figure 13] FIG. 13 is a diagram showing the sensitivity and cross sensitivity characteristics of the bridge circuit for measuring wheel load in the static load test results, and is a diagram showing the front and rear tangential force sensitivity. [Figure 14] FIG. 14 is a diagram showing the lateral force sensitivity-wheel load cross characteristics of the bridge circuit for measuring lateral force in the static load test results, and is a diagram showing lateral force sensitivity. [Figure 15] 15 is a diagram showing the lateral force sensitivity vs. wheel load crossover characteristics of the bridge circuit for measuring lateral force in the static load test results, and is a diagram showing the wheel load crossover sensitivity at Y=0 mm. [Figure 16] FIG. 16 is a diagram showing the lateral force sensitivity vs. wheel load crossover characteristics of the bridge circuit for measuring lateral force in the static load test results, and is a diagram showing the wheel load crossover sensitivity at Y=+20 mm. [Figure 17]FIG. 17 is a diagram showing the lateral force sensitivity vs. wheel load crossover characteristics of the bridge circuit for measuring lateral force in the static load test results, and is a diagram showing the wheel load crossover sensitivity at Y=-20 mm. [Figure 18] FIG. 18 is a diagram showing the front-rear tangential force cross sensitivity characteristics of the bridge circuit for measuring lateral force in the static load test results, and shows the front-rear tangential force cross sensitivity at Y=0 mm. [Figure 19] FIG. 19 is a diagram showing the cross sensitivity characteristics of the front and rear tangential forces of the bridge circuit for measuring lateral pressure in the static load test results, and shows the cross sensitivity of the front and rear tangential forces at Y=+10 mm. [Figure 20] FIG. 20 is a diagram showing the cross sensitivity characteristics of the front and rear tangential forces of the bridge circuit for measuring lateral pressure in the static load test results, and shows the cross sensitivity of the front and rear tangential forces at Y=−20 mm. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] FIG. 1 is a diagram showing the configuration of a wheel and the arrangement of strain gauges used in a lateral force measuring device or the like according to an embodiment.

[0013] FIG. 1 is a diagram showing the configuration of a wheel and the arrangement of strain gauges used in a lateral force measuring device or the like according to an embodiment. FIG. 1(a) is a view of a wheel 100 as seen from the axial direction and from the outside in the vehicle width direction. 1(b) and 1(c) are cross-sectional views taken along the arrows bb and cc in FIG. 1(a), respectively. The wheel 100 is, for example, an integrally rolled wheel in which a rim portion 110, a boss portion 120, a plate portion 130, and the like are integrally formed. The PQ wheel set of this embodiment is constructed by press-fitting boss portions 120 of a pair of left and right wheels 100 onto both ends of an axle (not shown).

[0014] The rim portion 110 is a tire portion provided on the outer peripheral edge of the wheel 100, and has a tread surface 111, a flange 112, and the like. The tread surface 111 is the outer peripheral surface of the rim portion 110, and is the portion that comes into contact with the head of a rail (not shown). The tread 111 has a predetermined tread gradient so that the outer side of the vehicle has a smaller diameter than the inner side, allowing the vehicle to travel smoothly on curved roads. The flange 112 is formed so as to protrude radially outward from the end of the tread 111 on the vehicle inner side in a flange-like shape. In FIG. 1(a), the numbers written along the circumferential direction on the rim portion 110 are circumferential position indicators used to indicate loading points in lateral force measurement and the like. The position indicators are arranged at equal intervals in the clockwise direction in FIG. 1(a) by dividing the wheel 100 into 32 parts in the circumferential direction.

[0015] The boss portion 120 is a cylindrical portion provided in the center of the wheel 100 and into which an axle (not shown) is press-fitted. The rim portion 110 and the boss portion 120 are formed to protrude from the plate portion 130 on both sides in the axle direction.

[0016] The plate portion 130 is a disk-shaped portion provided on the inner diameter side of the rim portion 110. The plate portion 130 is formed, for example, in the shape of a flat plate extending along a plane perpendicular to the axial direction of the axle. The boss portion 120 is provided in the center of the plate portion 130 .

[0017] The plate portion 130 has holes 131 formed therein for attaching strain gauges. The hole 131 is provided in the middle portion between the inner peripheral edge of the rim portion 110 and the outer peripheral edge of the boss portion 120 in the radial direction of the wheel 100. The holes 131 are arranged at equal intervals along the circumferential direction of the wheel 100, for example, at eight locations. The holes 131 are formed at positions corresponding to 0, 4, 8, 12, 16, 20, 24, and 28 in the above-mentioned position index. A strain gauge, which will be described below, is attached to the inner peripheral surface of the hole 131.

[0018] Strain gauges 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 6A, 6B, 7A, 7B, 8A, and 8B are attached to the inner circumferential surface of hole 131. Strain gauges 1A and 1B are arranged facing each other in the circumferential direction of wheel 110 on the inner circumferential surface of hole 131 provided at a position corresponding to position index 0 (phase / angle position around the axle).

[0019] The strain gauges 2A and 2B are arranged on the inner circumferential surface of a hole 131 provided at a location corresponding to the position indicator 4, facing each other in the circumferential direction of the wheel 110. The strain gauges 3A and 3B are arranged on the inner circumferential surface of a hole 131 provided at a location corresponding to the position indicator 8, facing each other in the circumferential direction of the wheel 110. The strain gauges 4A and 4B are arranged on the inner circumferential surface of a hole 131 provided at a location corresponding to the position indicator 12, facing each other in the circumferential direction of the wheel 110. The strain gauges 5A and 5B are arranged on the inner circumferential surface of a hole 131 provided at a location corresponding to the position indicator 16, facing each other in the circumferential direction of the wheel 110. The strain gauges 6A and 6B are arranged on the inner circumferential surface of a hole 131 provided at a location corresponding to the position indicator 20, facing each other in the circumferential direction of the wheel 110. The strain gauges 7A and 7B are arranged on the inner circumferential surface of a hole 131 provided at a location corresponding to the position indicator 24, facing each other in the circumferential direction of the wheel 110. The strain gauges 8A and 8B are arranged on the inner circumferential surface of a hole 131 provided at a location corresponding to the position indicator 28, facing each other in the circumferential direction of the wheel 110.

[0020] In order to adopt a lateral pressure measurement method using shear strain, strain gauges 1A, 1B, 3A, 3B, 5A, 5B, 7A, 7B, 8A, and 8B are provided with three points (three axes) of strain gauges per strain gauge, which are used, for example, for rosette analysis. To distinguish between these, a sub-number is assigned in addition to the main number. As shown in Figures 1(b) and 1(c), the branch number of the strain gauge whose head (facing the outer diameter of the wheel in the axial direction) is tilted toward the flange is set to 3, the branch number of the strain gauge used to measure the wheel load in the center is set to 2, and the branch number of the strain gauge whose head is tilted away from the flange is set to 1. Strain gauges 2A, 2B, 4A, 4B, 6A, 6B, 8A, and 8B are uniaxial strain gauges corresponding to branch number 2 (however, when configuring an adjacent hole utilization type bridge circuit, which will be described later, strain gauges 2A and 2B will also be triaxial strain gauges). Each strain gauge associated with branch number 2 constitutes a wheel load bridge circuit in a known continuous wheel load measuring device.

[0021] The wheel 100 is also provided with strain gauges 1a, 1a', 3a, 3a', 5a, 5a', 7a, and 7a'. These strain gauges form a known lateral pressure bridge circuit that measures lateral pressure based on bending deformation of the plate portion 130. The strain gauges 1a, 1a', 3a, 3a', 5a, 5a', 7a, and 7a' are arranged on the surface of the plate portion 130 (the side surface of the wheel 110) in an area on the inner diameter side of the hole 131. Strain gauges 1a and 1a' are arranged on the inner diameter side of hole 131 in which strain gauges 1A and 1B are provided. The strain gauge 1a is attached to the outer surface of the wheel 110 in the vehicle width direction. The strain gauge 1a' is attached to the inner surface of the wheel 110 in the vehicle width direction. The strain gauge 1a and the strain gauge 1a' are arranged opposite to each other in the direction of the rotation axis of the wheel 110, with the plate portion 130 sandwiched therebetween.

[0022] Strain gauges 3a and 3a' are arranged on the inner diameter side of hole 131 in which strain gauges 3A and 3B are provided. The strain gauge 3a is attached to the outer surface of the wheel 110 in the vehicle width direction. The strain gauge 3a' is attached to the inner surface of the wheel 110 in the vehicle width direction. The strain gauge 3a and the strain gauge 3a' are arranged opposite to each other in the direction of the rotation axis of the wheel 110, with the plate portion 130 sandwiched therebetween.

[0023] Strain gauges 5a and 5a' are arranged on the inner diameter side of hole 131 in which strain gauges 5A and 5B are provided. The strain gauge 5a is attached to the outer surface of the wheel 110 in the vehicle width direction. The strain gauge 5a' is attached to the inner surface of the wheel 110 in the vehicle width direction. The strain gauge 5a and the strain gauge 5a' are arranged opposite to each other in the direction of the rotation axis of the wheel 110, with the plate portion 130 sandwiched therebetween.

[0024] Strain gauges 7a and 7a' are arranged on the inner diameter side of hole 131 in which strain gauges 7A and 7B are provided. The strain gauge 7a is attached to the outer surface of the wheel 110 in the vehicle width direction. The strain gauge 7a' is attached to the inner surface of the wheel 110 in the vehicle width direction. Strain gauge 7a and strain gauge 7a' are arranged opposite to each other in the direction of the rotation axis of wheel 110, with plate portion 130 sandwiched therebetween.

[0025] FIG. 2 is a diagram showing the arrangement of only the minimum number of strain gauges required to verify an axisymmetric bridge circuit (a bridge circuit that is not symmetrical about the axis of rotation) among the strain gauges shown in FIG.

[0026] In the configuration shown in FIG. 2, in order to verify the configuration of a bridge circuit utilizing adjacent holes 131, triaxial strain gauges 2A-1, 2, 3 and 2B-1, 2, 3 are attached at the position "4" where a uniaxial strain gauge was to be attached in FIG. 1.

[0027] For comparison, an axially asymmetric bridge circuit is also configured for bending strain. In this case, since the attachment method shown in Figure 1 does not allow for the construction of a bridge circuit using the four-gauge method, the attachment positions of the strain gauges were shifted slightly in the circumferential direction of the wheel (left and right in Figure 2), and four single-axis strain gauges 1a'-1, 1a-2, 1a'-2, 1a-1 (two on the front side and two on the back side) were attached to only half of the wheel (the upper half in Figure 2), as shown in Figure 2.

[0028] FIG. 3 shows the basic form of an axially asymmetric bridge circuit for the lateral pressure measurement method utilizing shear strain. The bridge circuit is made by connecting strain gauges 1A-1, 1A-3, 1B-1, and 1B-3 in a circular pattern. It is connected and configured. The output of the bridge circuit is between strain gauges 1A-1 and 1A-3 and between strain gauge 1B- The voltage is between 1 and 1B-3. In the configuration of FIG. 3, the strain gauge in only one hole 131 completes the bridge circuit.

[0029] Figure 4 shows a bridge circuit (adjacent hole utilization type) that utilizes strain gauges in adjacent holes in the lateral pressure measurement method that utilizes shear strain. The configuration in FIG. 4 aims to reduce the harmonic components of the cross sensitivity characteristic to the wheel load. The bridge circuit is configured by connecting strain gauges 1A-1, 1B-1, 1A-3, 1B-3, 2B-1, 2A-1, 2B-3, and 2A-3 in sequence in a ring. The output of the bridge circuit is the voltage between strain gauges 1B-1 and 1A-3 and the voltage between strain gauges 2A-1 and 2B-3. In the configuration of FIG. 4, the strain gauges in two circumferentially adjacent holes 131 form a bridge circuit.

[0030] Figure 5 shows an axially asymmetric bridge circuit using bending strain for comparison. The bridge circuit is formed by connecting strain gauges 1a'-1, 1a-2, 1a'-2, and 1a-1 in a circular fashion. The output of the bridge circuit is between strain gauges 1a'-1 and 1a-2 and between strain gauge 1a The voltage is between '-2 and 1a-1. The configurations shown in FIGS. 3 to 5 are all bridge circuits based on the four-gauge method, and therefore have a temperature compensation function.

[0031] In the present invention, the arrangement of the strain gauges is not limited to this embodiment and can be changed as appropriate.

[0032] The output of each bridge circuit is processed by a calculation unit, which is a calculation means described later, and is used to calculate the lateral force Q. The calculation unit that calculates the lateral force, etc. can be configured as a computer having, for example, an information processing unit such as a CPU, a memory unit such as a RAM or ROM, an input / output interface, and a bus that connects these. The lateral force Q may be calculated offline, for example, at a ground facility by recording the bridge circuit output (distortion waveform) measured on board the vehicle. Furthermore, if the calculation unit has sufficient calculation capacity, the calculation may be performed in real time on board the vehicle or at a ground facility that can communicate with the vehicle.

[0033] Unlike axisymmetric bridge circuits, axisymmetric bridge circuits are characterized by the fact that the sensitivity characteristics that change with the rotation of the wheel are asymmetric with respect to the measurement baseline. In other words, the sensitivity characteristics as a sensor itself contain an offset. In conventional axisymmetric bridge circuits, the offset in the sensitivity characteristics as a sensor is so small that it can be ignored (Fig. 6(a)), so in order to remove other causes, such as offsets caused by amplifier drift or the initial load acting during zero shift (Fig. 6(b)), signal processing equivalent to a filter with high-pass characteristics was performed (Fig. 6(c)).

[0034] On the other hand, in an axisymmetric bridge circuit, an offset occurs in the sensitivity characteristics themselves, which change with the rotation of the wheel (FIG. 7(a)). Therefore, if a high-pass filter is applied as in an axisymmetric bridge circuit, even offsets that should not be removed will be removed, resulting in a large error in the force measurement results (FIGS. 7(b) and 7(c)). In this embodiment, the amount of offset that should be removed corresponding to the axisymmetric bridge circuit is calculated, and a process for removing the offset is performed (FIG. 8). This calculation process is described below.

[0035] The offset amount that should be taken into account in the sensor and the offset amount that should be removed cannot be removed in frequency space, so they cannot be separated using a filter such as a high-pass filter designed in frequency space. To solve this problem, this embodiment utilizes a model expressed as a Fourier series that includes an offset term. This model can be constructed using the results of static load tests performed for calibration on all PQ wheelsets.

[0036] (Model description) The periodic functions f(φ) and g(φ, y) related to the wheel rotation angle φ are defined as the following equations (1) and (2).

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[0037] where Sfn, Cfn, etc. are Fourier coefficients and have the dimension of strain sensitivity to force. Also, N is the approximation order, y is the contact position in the left-right direction, and Df, Dg, and Dh are offset terms that are inherent characteristics of the sensor. The offset terms are

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[0038]

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[0039] In an actual PQ axle equipped with an axisymmetric bridge circuit, there are two bridge systems for measuring wheel load and four bridge circuits for measuring lateral force, and for each bridge circuit, a total of six relational equations such as equations (9) and (10) can be established as equations (11) to (16).

[0040] Specifically, for the two bridge circuits for wheel load measurement,

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[0041] The equations (11) to (16) are constructed by using the product of sensitivity and cross sensitivity, force and contact position, and an unknown offset term for each bridge output. On the other hand, if the bridge circuit output is obtained as a waveform for one wheel rotation, it is also possible to fit equation (3) directly. In this way, the function obtained by directly fitting to the real signal can be

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[0042] In the expansion of the equations up to this point, the variable φ is an angle variable with the reference position at the time of testing as its origin, and does not necessarily match the phase based on the contact position during actual driving. Now, we introduce an angle variable Φ with the actual contact position φ0 as its origin. The relationship between variables φ and Φ is expressed by equation (19).

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[0043] By introducing this variable transformation, the basis function vector can be expressed as in equation (20).

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[0044] Based on the above, we derive a relational expression consisting of the waveforms obtained during actual driving and the test results, and organize the phase adjustment procedure. For the two bridge circuits used to measure wheel load, we assume axisymmetric bridge circuits, as in the past, so Df in equation (1) is small enough to be ignored, and Dp1 and Dp2 in equations (11) and (12) can be removed using a high-pass filter, as in the past. Therefore, we perform phase adjustment and calculate the average value of the acting force over one wheel rotation.

[0045] First, with respect to equations (11) and (12), equation (21) is assumed approximately.

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[0046]

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[0047]

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[0048]

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[0049]

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[0050] So far, we have formulated equations using only one bridge circuit. However, when considering the outputs of two bridge circuits simultaneously, we use the matrix

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[0051] In this embodiment, the evaluation function is derived taking into account the cross sensitivity term for lateral force on the wheel load measurement bridge. This is because the relative influence of this cross sensitivity becomes large, particularly in the region where the derailment coefficient Q / P is large, and it is necessary to take this into account and make corrections. Formally, the same evaluation function is obtained as when the influence of lateral force is not considered. However, the cross sensitivity for lateral force is generally small, and its configuration can change due to accidental factors such as errors in the installation of strain gauges, so in some cases, the matrix

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[0052] First, the right side of equation (22) is divided into a part related to P and T and a part related to Q. That is, equation (26) is obtained.

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[0053] (Calculation of offset amount) It is assumed that at least P, T, and φ0 are known from the calculations up to the previous section. Then, by expressing the four equations (13) to (16) in the same form as equation (21), equation (29) is obtained.

[0054]

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[0055] In an axially asymmetric bridge circuit, the offset term Dqj cannot be removed using a high-pass filter or the like, so it is calculated using the following calculation procedure. Reorganizing this equation into parts that include unknown variables and parts that do not, we obtain equation (30).

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[0056] First, note that it can be expressed as equation (32).

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[0057]

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[0058]

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[0059]

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[0060] The flow of the entire offset calculation process is shown in Figure 9. When minimizing the evaluation function shown in equation (28), the lateral force Q has not yet been calculated, and it is not possible to correct the cross sensitivity of the lateral force to the strain signal for wheel load measurement in at least one optimization calculation. Therefore, first, Q = 0 is set, and Φ0 and f that minimize the evaluation function E(Φ0;0) are calculated. PT By calculating these, the lateral force is calculated by the procedure in the previous section.

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[0061] FIG. 10 is a block diagram showing an example implementation when applied to PQ measurement for offset removal.

[0062] The calculation unit 200 for calculating the lateral force of the measuring device of this embodiment has an offset calculation unit 210 and a measurement value calculation unit 220.

[0063] The offset calculation unit 210 calculates a second offset amount based on an output model (Equation (36)) of the bridge circuit, which is generated based on the relationship (Equations (9) and (10)) between the wheel load, lateral force, and longitudinal tangential force acting between the wheel and rail obtained in a static load test and the output of the bridge circuit. The model includes an offset term (hereinafter also referred to as a first offset term) of the sensitivity characteristics of the bridge circuit as a sensor, which is caused by changes in the sensitivity characteristics of the bridge circuit as the wheel rotates, and an offset term (hereinafter also referred to as a second offset term) that should be removed and is caused by factors other than the changes in the sensitivity characteristics as the wheel rotates, such as amplifier drift or an initial load acting during zero shift. The measurement value calculation unit 220 calculates the lateral force or contact position by removing the second offset amount from the output of the bridge circuit.

[0064] Specifically, the offset calculation unit 210 has an AD conversion unit 211 and an arithmetic processing unit 212. The arithmetic processing unit 212 has a one-rotation waveform extraction unit 221 and an offset calculation processing unit 222. The one-rotation waveform extraction unit 221 extracts the bridge circuit output (distortion waveform) digitally converted by the AD conversion unit 211 for one rotation of the wheel 100. The offset calculation processing unit 222 repeats the calculation process of equation (36) a predetermined number of times based on the distortion waveform for one rotation extracted by the one-rotation waveform extraction unit 221, and outputs the calculation result as the offset amount to be removed from the axisymmetric block circuit output.

[0065] The measurement value calculation section 220 has a DA conversion section 231, a differential amplifier 232, and a measurement value calculation processing section 233. The output of the offset calculation section 210 is converted to analog by the DA conversion section 231, and then subtracted by the differential amplifier 232 from the distorted waveform output by the bridge circuit. The measurement value calculation processing section 233 calculates the lateral force Q based on the distorted waveform from which the offset amount to be removed has been subtracted by the differential amplifier 232.

[0066] The calculation unit 200 is configured as a computer having an information processing unit such as a CPU (Central Processing Unit), storage units such as RAM and ROM, an input / output interface, and buses connecting these, and can perform the above calculations by executing a predetermined application program. Also, the calculation unit 200 can complete up to the offset subtraction within the program, without necessarily converting the offset calculation result into a digital-to-analog conversion and generating an electrical signal.

[0067] The calculation of the average value of the lateral contact position of the wheel per one wheel revolution from the bridge circuit output can be performed using the contact position calculation method described in Non-Patent Document 5. Even in this case, the offset amount in the axisymmetric bridge circuit is calculated by the offset calculation unit 210 using a method of solving a model including the offset term described above, and the measurement value calculation unit 220 calculates the contact position by removing the offset amount that should be removed.

[0068] (Simulation results for offset calculation) The offset calculation method of this embodiment was used to calculate the offset amount described above for the simulated strain signal obtained using the static load test results for the PQ wheelset. The sensitivity and cross sensitivity characteristics were fitted using equation (1) or equation (2).

[0069] The sensitivity and cross sensitivity characteristics obtained from the static load test results for the PQ wheelset are shown in Figures 11 to 20. An adjacent hole utilization type bridge circuit shown in Figure 4 was configured for the A-side wheel, and a basic type bridge circuit shown in Figure 3 was configured for the B-side wheel. In Figures 11 to 20, Ap1 and Ap2 are the wheel loads of the A-side wheels. Aq1, Aq2, Aq3, and Aq4 are the lateral forces of the A-side wheels. Bp1 and Bp2 are the wheel loads of the B-side wheels. Bq1, Bq2, Bq3, and Bq4 are the lateral forces of the A-side wheels.

[0070] The simulated strain signal is generated by setting the wheel load P, lateral force Q, longitudinal tangential force T, and lateral contact position y as constant values, and calculating the time series of strains εp and εq using equations (9) and (10). However, the wheel rotation angle φ is calculated as φ(t+Δ)=φ(t)+Δωt, where the initial value is 0, the rotational angular velocity is ω, the time is t, and the sampling period is Δt. In the verification of this embodiment, the sampling period was set to 0.001 sec, the rotational angular velocity was set to 20 rad / sec, and a simulated strain signal for 20 seconds was generated under the conditions shown in Table 1. [Table 1]

[0071] 11 to 13 are diagrams showing the sensitivity and cross sensitivity characteristics of the bridge circuit for wheel load measurement in the results of static load tests, where FIG. 11 is a diagram showing the wheel load sensitivity characteristics of the bridge circuit for wheel load measurement, FIG. 12 is a diagram showing the lateral force cross sensitivity characteristics of the bridge circuit for wheel load measurement, and FIG. 13 is a diagram showing the front and rear tangential force sensitivity characteristics of the bridge circuit for wheel load measurement. Figures 14 to 17 are diagrams showing the lateral force sensitivity and wheel load cross sensitivity characteristics of the bridge circuit for measuring lateral force from the results of static load tests, with Figure 14 showing the lateral force sensitivity, Figure 15 showing the wheel load cross sensitivity at Y=0 mm, Figure 16 showing the wheel load cross sensitivity at Y=+20 mm, and Figure 17 showing the wheel load cross sensitivity at Y=-20 mm. 18 to 20 are graphs showing the front-rear tangential force cross sensitivity characteristics of the bridge circuit for measuring lateral force in the static load test results. Fig. 18 shows the front-rear tangential force cross sensitivity at Y=0 mm, Fig. 19 shows the front-rear tangential force cross sensitivity at Y=+10 mm, and Fig. 20 shows the wheel load cross sensitivity indicating the front-rear tangential force cross sensitivity at Y=-20 mm. Note that Y is the value of the contact position.

[0072] Table 2 shows the calculation results for the offset amount, etc. for the B-side wheel equipped with a basic bridge circuit. Table 2 also summarizes the error between the time-averaged values ​​of the calculation results for the offset amount, etc. and the assumed values. In the above calculations, the calculation was repeated five times to correct for the lateral force cross sensitivity. For all conditions, the calculated values ​​were roughly close to the acting force, contact position, and offset amount assumed when generating the simulated waveform. However, the greater the lateral force, the greater the fluctuation in the offset amount calculation results. Therefore, when actually removing the offset, it is preferable to take measures such as using the average value of at least several calculation results. [Table 2]

[0073] The largest offset error in the above verification was the offset of the bridge circuit of the fourth system, 4

number

[0074] Similar results were obtained when calculating the offset for the A-side wheel equipped with an adjacent hole-utilizing bridge circuit, and even when the offset error is the largest, it can be considered a sufficiently small error for the evaluation of driving safety. Therefore, even in an adjacent hole utilizing bridge circuit, sufficient accuracy is achieved under ideal circumstances, and the calculation principle is valid.

[0075] [Note] (1) Measuring equipment The contents of the above-described embodiments can be understood, for example, as follows. The above-mentioned measuring device is a measuring device for measuring the lateral force or contact position between the wheel 100 of the railway vehicle and the rail, The wheel 100 is a rim portion 110 provided on an outer peripheral edge portion and having a tread surface; a boss portion 120 provided in the center to which an axle is attached; a plate portion 130 provided between the rim portion and the boss portion, The measuring device is a plurality of strain gauges 1A-1, 1A-3, 1B-1, 1B-3 or a plurality of strain gauges 1A-1, 1B-1, 1A-3, 1B-3, 2A-1, 2B-1, 2A-3, 2B-3 that penetrate the plate portion 130 in the direction of the rotational axis of the wheel 100 and are attached to the inner surfaces of holes arranged around the rotational axis, and that detect shear strain of the plate portion due to lateral pressure; A calculation unit 200 that calculates the lateral pressure or contact position based on the output of a bridge circuit (Figs. 3 and 4) that is asymmetric with respect to the rotation center axis and is composed of strain gauges. Equipped with The calculation unit 200 an offset calculation unit 210 for calculating a second offset amount based on an output model (equation (36)) of the bridge circuit, which is generated based on the relationship (equations (9) and (10)) between the wheel load (P), lateral force (Q), and longitudinal tangential force (T) acting between the wheel and rail obtained in a static load test and the output of the bridge circuit, and which includes a first offset term (offset of the sensitivity characteristics as a sensor) caused by the sensitivity characteristics of the bridge circuit that change with the rotation of the wheel, and a second offset term caused by a cause other than the sensitivity characteristics that change with the rotation of the wheel (for example, an offset that should be removed due to amplifier drift or an initial load acting at zero shift); a measurement value calculation unit 220 that calculates the lateral force or contact position by removing the second offset amount from the output of the bridge circuit; The present invention is characterized by having the following.

[0076] In this way, the offset amount caused by factors other than the sensitivity characteristics that change with wheel rotation, such as the temperature drift of the amplifier, is calculated and removed from the output of the bridge circuit, allowing for highly accurate measurement of lateral force or contact position.

[0077] (2) Arithmetic device The offset calculation unit 210 described above A bridge circuit comprising a plurality of strain gauges attached to a railway vehicle wheel having a rim portion on the outer periphery where a tread surface is formed, a boss portion in the center to which an axle is attached, and a plate portion provided between the rim portion and the boss portion, the bridge circuit comprising a plurality of strain gauges that penetrate the plate portion in the direction of the central axis of rotation of the wheel and are attached to the inner surface of holes arranged around the central axis of rotation to detect shear strain in the plate portion due to lateral pressure, is input, The second offset amount is calculated based on an output model (equation (36)) of the bridge circuit, which is generated based on the relationship (equations (9) and (10)) between the wheel load, lateral force, and longitudinal tangential force acting between the wheel and rail obtained in the static load test and the output of the bridge circuit, and includes a first offset term arising from the sensitivity characteristics of the bridge circuit that change with the rotation of the wheel, and a second offset term arising from a cause other than the sensitivity characteristics that change with the rotation of the wheel.

[0078] In this way, the offset amount that occurs due to factors other than the sensitivity characteristics that change with wheel rotation, such as the temperature drift of the amplifier, is calculated, and by removing this from the output of the bridge circuit, it is possible to measure the lateral force or contact position with high accuracy. [Explanation of symbols]

[0079] 1A~8B Strain gauges for wheel load and lateral force measurement (lateral force measurement method using shear strain) 1a~7a Strain gauges for measuring lateral pressure (plate bending) 100 wheels 110 Rim 111 tread 112 flange 120 Boss section 130 Board part 131 holes 200 Arithmetic section 210 Offset calculation unit 220 Measurement value calculation unit

Claims

1. A measuring device for measuring lateral pressure or contact position between a wheel of a railway vehicle and a rail, The wheel is a rim portion provided on an outer peripheral edge portion and having a tread surface; a boss portion provided in the center to which an axle is attached; a plate portion provided between the rim portion and the boss portion, The measuring device is a plurality of strain gauges that penetrate the plate portion in the direction of the central axis of rotation of the wheel and are attached to inner surfaces of holes arranged around the central axis of rotation of the wheel, and that detect shear strain of the plate portion due to the lateral pressure; a calculation unit that is a bridge circuit configured with the strain gauges and calculates the lateral force or the contact position based on an output of the bridge circuit that is asymmetric with respect to the rotation center axis; Equipped with The calculation unit an offset calculation unit that calculates a second offset amount based on an output model of the bridge circuit, the output model being generated based on the relationship between the wheel load, the lateral force, and the longitudinal tangential force acting between the wheel and the rail, which are obtained in a static load test, and the output of the bridge circuit, the model including a first offset term arising from a sensitivity characteristic of the bridge circuit that changes with wheel rotation, and a second offset term arising from a cause other than the sensitivity characteristic that changes with wheel rotation; a measurement value calculation unit that calculates the lateral force or the contact position by removing the second offset amount from the output of the bridge circuit; and A measuring device comprising:

2. a bridge circuit comprising a plurality of strain gauges affixed to a railway vehicle wheel having a rim portion provided on the outer periphery thereof with a tread surface, a boss portion provided in the center to which an axle is attached, and a plate portion provided between the rim portion and the boss portion, the bridge circuit comprising the plurality of strain gauges penetrating the plate portion in the direction of the central axis of rotation of the wheel and affixed to the inner surface of a hole arranged around the central axis of rotation of the wheel, and detecting shear strain in the plate portion due to lateral pressure, The second offset amount is calculated based on an output model of the bridge circuit, which is generated based on the relationship between the wheel load, the lateral force, and the longitudinal tangential force acting between the wheel and the rail obtained in a static load test, and the output of the bridge circuit, and the model includes a first offset term caused by a sensitivity characteristic of the bridge circuit that changes with the rotation of the wheel, and a second offset term caused by a cause other than the sensitivity characteristic that changes with the rotation of the wheel. A computing device characterized by:

3. A method for measuring lateral force or contact position between a wheel of a railway vehicle and a rail, comprising: The wheel is a rim portion provided on an outer peripheral edge portion and having a tread surface; a boss portion provided in the center to which an axle is attached; a plate portion provided between the rim portion and the boss portion, The measurement method includes: a plurality of strain gauges are attached to inner surfaces of holes that penetrate the plate portion in the direction of the central axis of rotation of the wheel and are arranged around the central axis of rotation of the wheel, the strain gauges detecting shear strain of the plate portion caused by the lateral pressure; an offset calculation unit calculates a second offset amount based on an output model of the bridge circuit, the output model being generated based on the relationship between the wheel load, the lateral force, and the longitudinal tangential force acting between the wheel and the rail, which are obtained in a static load test, and an output of the bridge circuit, the model including a first offset term arising from a sensitivity characteristic of the bridge circuit that changes with wheel rotation, and a second offset term arising from a cause other than the sensitivity characteristic that changes with wheel rotation; a measurement value calculation unit that calculates the lateral force or the contact position by removing the second offset amount from the output of the bridge circuit; A measuring method characterized by:

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