Measuring apparatus and measuring method

Abstract

To provide a measuring device and method for improving the measurement accuracy of lateral pressure or a contact position.SOLUTION: A measurement device that measures a lateral pressure Q or a contact position between a wheel 100 of a railway vehicle and a rail, the measurement device including a plurality of strain gauges that detect a shear strain of a plate portion caused by the lateral pressure, and a calculation unit 400 that continuously calculates the lateral pressure or the contact position on the basis of an output of a bridge circuit that includes the strain gauges and is asymmetric with respect to a rotation center axis, the characteristic of the output sensitivity of the bridge circuit according to the wheel load between the wheel and the rail and the front-rear tangential force of the wheel changes with the rotation of the wheel, and the calculation unit calculates the lateral pressure or the contact position based on the cross sensitivity vector of interest determined by the characteristic of the output sensitivity of the bridge circuit or the inverse element orthogonal to the sensitivity vector.SELECTED DRAWING: Figure 1

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 the lateral force of a railway vehicle wheel or the contact position between the wheel and the rail in the sleeper direction. [Background technology]

[0002] To assess the running safety of railway vehicles, a known method is to measure 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. However, if it were possible to measure the contact position in addition to the contact force, it could contribute to elucidating the phenomenon related to wheel-rail contact and to establishing a more in-depth running safety assessment.

[0003] 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.

[0004] In light of the above, a method has been proposed to measure the contact position by attaching a strain gauge for measuring the contact position to the PQ wheelset (Non-Patent Documents 1, 2, 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).

[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 PQ wheelsets. 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] In light of these background technologies, one prior art proposal for a bridge circuit for measuring lateral force on a PQ wheelset is to separate the strain gauges on the 180-degree opposite side of the axle from a given strain gauge, which are normally combined into a single bridge circuit, to form four bridge circuits for measuring lateral force with a phase difference of 90 degrees (hereinafter referred to as an axisymmetric bridge circuit) (Non-Patent Document 6).Non-Patent Document 6 shows that making the bridge circuit axisymmetric reduces the influence of wheel load cross sensitivity in the lateral force measurement bridge circuit.Meanwhile, another common method for evaluating driving safety is to convert strain sensitivity to circumferential force of the wheel into continuous contact force information using wheel rotation angle sensors (Non-Patent Document 7). [Prior art documents] [Non-patent literature]

[0007] [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. [Non-patent document 6] Hondo, "Reduction of Cross Sensitivity Ratio by Axial Asymmetrical Bridge Circuit in PQ Wheelset Utilizing Shear Strain (Verification by Numerical Analysis)," Dynamics & Design Conference 2022, Paper No. 520, 2023. [Non-Patent Document 7] Hiroaki Ishida, Masaki Matsuo, Kazuhiko Tezuka, Kenji Ueki, "A New Method for Continuous Measurement of Wheel Load, Lateral Force, and Derailment Coefficient of Railway Vehicles (Development of Measuring Device)," Transactions of the Japan Society of Mechanical Engineers, Series C, Vol. 63, No. 614 (1997), pp. 3417-3423. Summary of the Invention [Problem to be solved by the invention]

[0008] As mentioned above, one common method for evaluating driving safety is to convert the strain sensitivity to circumferential force of the wheel into continuous contact force information using a wheel rotation angle sensor (Non-Patent Document 7). However, there is no solution to the problem of how to accurately calculate continuous lateral force and contact position using waveforms obtained from an axisymmetric bridge circuit.

[0009] The present invention has been made in view of the above problems, and its object is to provide an apparatus and method for accurately calculating continuous lateral pressure or contact position from a waveform obtained from an axially asymmetric bridge circuit. [Means for solving the problem]

[0010] A measuring device according to one 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, in which the wheel has 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, and the measuring device is equipped with a plurality of strain gauges which penetrate the plate portion in the direction of the central axis of rotation of the wheel and are affixed to the inner surfaces of holes arranged around the central axis of rotation of the wheel and detect shear strain in the plate portion due to the lateral force, and a calculation unit which continuously calculates the lateral force or contact position based on the output of a bridge circuit composed of strain gauges and which is asymmetric with respect to the central axis of rotation, and the output sensitivity characteristics of the bridge circuit according to the wheel load between the wheel and the rail and the longitudinal tangential force of the wheel change as the wheel rotates, and the calculation unit calculates the lateral force based on the inverse of a lateral force sensitivity vector which is orthogonal to a proportional coefficient vector of wheel load cross sensitivity, which is determined by the output sensitivity characteristics of the bridge circuit.

[0011] A measurement method according to one aspect of the present invention is a method for measuring lateral force or contact position between a wheel of a railway vehicle and a rail, 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 provided between the rim portion and the boss portion, and the method comprises: a plurality of strain gauges that penetrate the plate portion in the direction of the wheel's central axis of rotation and are affixed to the inner surfaces of holes arranged around the wheel's central axis of rotation to detect shear strain in the plate portion due to lateral force; and a bridge circuit composed of strain gauges, the bridge circuit being asymmetric with respect to the central axis of rotation; and a calculation unit that continuously calculates the lateral force or contact position based on the output of the bridge circuit, the bridge circuit having output sensitivity characteristics that correspond to the wheel load between the wheel and the rail and the longitudinal tangential force of the wheel, which change as the wheel rotates, and the calculation unit calculates the lateral force based on the inverse of the lateral force sensitivity vector that is orthogonal to the proportional coefficient vector of wheel load cross sensitivity, which is determined by the output sensitivity characteristics of the bridge circuit. [Effects of the Invention]

[0012] According to the present invention, the influence of cross sensitivity is almost completely eliminated, and the lateral pressure or contact position can be calculated with reduced error. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing a configuration for measuring lateral pressure and contact position according to an embodiment. [Figure 2] FIG. 2 is a diagram showing the configuration of a wheel and the arrangement of strain gauges used in the lateral force measuring device and the like of the embodiment. [Figure 3] FIG. 3 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 4] FIG. 4 shows the basic form of an axially asymmetric bridge circuit for the lateral pressure measurement method utilizing shear strain. [Figure 5] Figure 5 shows a bridge circuit using adjacent strain gauges in a lateral pressure measurement method that utilizes shear strain. [Figure 6] Figure 6 shows an axially asymmetric bridge circuit using bending strain. [Figure 7] FIG. 7 is a diagram showing the gradient of the cross sensitivity function (cross wheel load sensitivity) for an actual PQ wheelset. [Figure 8] FIG. 8 is a diagram showing the cross sensitivity function (front and rear tangential force cross sensitivity) of an actual PQ wheelset. [Figure 9] FIG. 9 is a diagram showing the intercept of the cross sensitivity function (cross wheel load sensitivity) for an actual PQ wheelset. [Figure 10] FIG. 10 is a diagram showing the intercepts of the cross sensitivity function (front and rear tangential force cross sensitivity) for an actual PQ wheelset. [Figure 11] FIG. 11 is a diagram showing a weighting function when the pseudo-inverse matrix of Equation 3 is used. [Figure 12] FIG. 12 is a diagram showing a weighting function when a simultaneous equation is used that takes into account the lateral force and the contact position. [Figure 13]FIG. 13 is a diagram showing a weighting function when simultaneous equations that take into account lateral force and contact position are used. [Figure 14] FIG. 14 is a diagram showing a weighting function when an inverse element orthogonal to only the proportional coefficient vector of the wheel load cross sensitivity is used. [Figure 15] FIG. 15 is a diagram showing weighting functions when inverse elements orthogonal to the proportionality coefficient vectors of the wheel load cross sensitivity and the front-rear contact force cross sensitivity are used. [Figure 16] FIG. 16 is a diagram showing the results of the lateral pressure continuation process under condition 1. [Figure 17] FIG. 17 is a diagram showing the results of the lateral pressure continuation process under condition 2. [Figure 18] FIG. 18 is a diagram showing the results of the lateral pressure continuation process under condition 3. [Figure 19] FIG. 19 is a diagram showing the results of the lateral pressure continuation process under condition 4. [Figure 20] FIG. 20 is a diagram showing the results of the contact position continuation process under condition 1. [Figure 21] FIG. 21 is a diagram showing the results of the contact position continuation process under condition 2. [Figure 22] FIG. 22 is a diagram showing the results of the contact position continuation process under condition 3. In FIG. [Figure 23] FIG. 23 is a diagram showing the results of the contact position continuation process under condition 4. DETAILED DESCRIPTION OF THE INVENTION

[0014] [Configuration of measurement equipment] A measuring device and a measuring method according to one embodiment of the present invention will be described below with reference to the drawings. Fig. 1 shows the schematic configuration of a measuring device for measuring lateral force or contact position. This measuring device comprises a PQ wheelset 10, a slip ring device 200, a strain signal processing unit 300, and a calculation unit 400.

[0015] The PQ wheelset 10 is a wheelset for measuring the wheel load P, lateral force Q, and longitudinal tangential force T acting between the wheel and rail using strain gauges 1A-6A (Fig. 2) attached to the wheel 100. The outputs of the strain gauges 1A-6A are input to a strain signal processing unit 300 via a slip ring device 200. The strain signal processing unit 300 performs signal processing such as amplification or AD conversion on the outputs of the strain gauges 1A-6A and supplies the results to a calculation unit 400. The calculation unit 400 calculates the lateral force or contact position. In this specification, "continuous" refers to measuring the wheel rotation angle simultaneously with the wheel strain to calculate continuous wheel load, lateral force, or contact position. This is a technique in contrast to the intermittent method, which reads the peak value of strain and measures only when force is acting.

[0016] FIG. 2 is a diagram showing the configuration of a wheel and the arrangement of strain gauges used in the lateral force measuring device and the like of the embodiment.

[0017] FIG. 2(a) is a view of the wheel 100 as seen from the axial direction and from the outside in the vehicle width direction. 2(b) and 2(c) are cross-sectional views taken along the arrows bb and cc in FIG. 2(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).

[0018] 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. 2(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.

[0019] 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.

[0020] 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 .

[0021] 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.

[0022] 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. The strain gauges 1A and 1B are arranged facing each other in the circumferential direction of the wheel 100 on the inner circumferential surface of a hole 131 provided at a position corresponding to position index 0 (phase and angular position around the axle).

[0023] 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 100. 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 100. 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 100. 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 100. 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 100. The strain gauges 7A and 7B are arranged on the inner circumferential surface of a hole 131 provided at a position corresponding to the position indicator 24, facing each other in the circumferential direction of the wheel 100. 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 100.

[0024] 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 2(b) and 2(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 for measuring the central wheel load is set to 2, and the branch number of the strain gauge whose head is tilted away from the flange is set to 1. Note that 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 as described below, strain gauges 2A and 2B are also 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.

[0025] 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 100) in an area on the inner diameter side of the hole 131.

[0026] 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 100 in the vehicle width direction. The strain gauge 1a' is attached to the inner surface of the wheel 100 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 100, with the plate portion 130 sandwiched therebetween.

[0027] 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 100 in the vehicle width direction. The strain gauge 3a' is attached to the inner surface of the wheel 100 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 100, with the plate portion 130 sandwiched therebetween.

[0028] 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 100 in the vehicle width direction. The strain gauge 5a' is attached to the inner surface of the wheel 100 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 100, with the plate portion 130 sandwiched therebetween.

[0029] 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 100 in the vehicle width direction. The strain gauge 7a' is attached to the inner surface of the wheel 100 in the vehicle width direction. The strain gauge 7a and the strain gauge 7a' are arranged opposite to each other in the direction of the rotation axis of the wheel 100, with the plate portion 130 sandwiched therebetween.

[0030] FIG. 3 is a diagram showing the arrangement of only the minimum number of strain gauges required for verifying an axisymmetric bridge circuit (a bridge circuit that is not symmetrical about the axis of rotation) among the strain gauges shown in FIG. In the configuration shown in FIG. 3, 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. 2.

[0031] For comparison, an axially asymmetric bridge circuit is also configured for bending strain. In this case, since the attachment method shown in Figure 2 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 3), 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 3), as shown in Figure 3.

[0032] FIG. 4 shows the basic form of an axially asymmetric bridge circuit for the lateral pressure measurement method utilizing shear strain. The bridge circuit is formed by connecting strain gauges 1A-1, 1A-3, 1B-1, and 1B-3 in a circular fashion. The output of the bridge circuit is the voltage between strain gauges 1A-1 and 1A-3 and the voltage between strain gauges 1B-1 and 1B-3. In the configuration of FIG. 4, the strain gauge in only one hole 131 completes the bridge circuit.

[0033] Figure 5 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. 5 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, 2A-1, 2B-1, 2A-3, and 2B-3 in a circular fashion. 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. 5, a bridge circuit is formed by strain gauges in two circumferentially adjacent holes 131 (first hole and second hole of the present invention).

[0034] Figure 6 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 the voltage between the strain gauges 1a'-1 and 1a-2 and the voltage between the strain gauges 1a'-2 and 1a-1. The configurations shown in FIGS. 4 to 6 are all bridge circuits based on the four-gauge method, and therefore have a temperature compensation function.

[0035] In the present invention, the arrangement of the strain gauges is not limited to this embodiment and can be changed as appropriate. In this embodiment, all four bridge circuits required for continuous lateral force measurement and contact position measurement are configured in each method. For example, the basic form of an axisymmetric bridge circuit is composed of a bridge circuit configured with a strain gauge attached to the hole 131 at the "0" position, a bridge circuit configured with a strain gauge attached to the hole 131 at the "8" position, a bridge circuit configured with a strain gauge attached to the hole 131 at the "16" position, and a bridge circuit configured with a strain gauge attached to the hole 131 at the "24" position.

[0036] In addition, the adjacent hole utilization type is composed of a bridge circuit made up of strain gauges attached to holes 131 at the positions "0-4", a bridge circuit made up of strain gauges attached to holes 131 at the positions "8-12", a bridge circuit made up of strain gauges attached to holes 131 at the positions "16-20", and a bridge circuit made up of strain gauges attached to holes 131 at the positions "24-28".

[0037] The output of each bridge circuit is processed by a calculation unit 400, which is a calculation means for calculating the lateral force Q and the contact position, and is used to calculate the lateral force Q and the contact position. The calculation unit 400 can be configured as a computer having, for example, an information processing unit such as a CPU, a storage unit such as a RAM or a ROM, an input / output interface, and a bus connecting these. The calculation of the lateral force Q and the contact position may be performed offline by, for example, recording the bridge circuit output (distortion waveform) measured on board the vehicle and bringing it back to, for example, a ground facility. Furthermore, if the calculation unit has sufficient calculation capacity, the calculation can be performed in real time on board the vehicle or at a ground facility that can communicate with the vehicle.

[0038] [Contact force continuity processing method] (Explanation of the formulation of bridge output and contact force) First, the relationship between the output of the bridge circuit for measuring lateral force and the contact force is shown as Equation (1).

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[0039] Here, ε is the bridge output for measuring lateral force, Q, P, and T are the lateral force, wheel load, and front-rear tangential force, respectively, and φ and y are the contact positions in the circumferential direction and left-right direction of the wheel, respectively. Also, the vector H(φ) is a vector-valued function of φ, which represents the strain output (sensitivity) per unit. The vector α P (φ) is a vector-valued function of φ, which represents the proportionality coefficient of the strain output per unit wheel load (cross sensitivity) with respect to the lateral contact position y. Vector β P (φ) is a vector-valued function of φ, which represents the intercept of the strain output per unit wheel load (cross sensitivity). Vector α T (φ) is a vector-valued function of φ, which represents the proportionality coefficient of the strain output (cross sensitivity) per unit longitudinal tangential force with respect to the lateral contact position y. Vector β T (φ) is a vector-valued function of φ that represents the intercept of the strain output per unit longitudinal tangential force (cross sensitivity).

[0040] Here, four pairs of axisymmetric bridge circuits are assumed, so the dimension of each vector is 4. Of these, the bridge output ε is a measured value obtained from the PQ wheelsets every moment, and φ is assumed to be obtained from a rotation angle sensor attached to the shaft end, such as a rotary encoder, and both are assumed to be known.

[0041] (Explanation of processing using conventional weighting functions) First, we will explain the conventional continuity processing method using a weighting function. This method does not take into account the influence of wheel load or front and rear tangential forces, and considers the relationship between bridge output and lateral force as shown in equation (2),

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[0042]

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[0043] (Explanation of continuation processing using simultaneous equations that simultaneously consider lateral pressure and contact position) As a method for continuously calculating lateral force, we will explain a continuation processing method using simultaneous equations that simultaneously considers lateral force and contact position. This method uses the simultaneous equations shown in equation (4) with lateral force Q and contact position y as unknowns, and uses a pseudo-inverse matrix to calculate lateral force Q and simultaneously calculate contact position y, similar to the continuation processing method using a weighting function.

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[0044] In this method, the coefficient matrix includes wheel load P and front / rear tangential force T, but these are assumed to be calculated separately from a bridge circuit used to measure wheel load. In principle, this method can completely eliminate the influence of wheel load and front / rear tangential force if all measurements are obtained with ideal accuracy, making it a highly accurate method for calculating lateral force.

[0045] However, in reality, coefficient errors are included in P, T, and φ, which make up the coefficient matrix. In particular, for the circumferential contact position φ, errors occur in the measurement value obtained by a rotation angle sensor (e.g., a rotary encoder) due to the forward and backward movement of the contact point in curved sections, resulting in errors in the sensitivity and cross sensitivity function. At this time, errors naturally occur due to errors in the sensitivity function vector H(φ), but similar errors also occur in the calculation of the wheel load P and the front and rear tangential force T, which leads to errors in the coefficient matrix and bias vector in equation (4), so the impact of this must be evaluated.

[0046] (Explanation of the continuation processing method using inverse mapping orthogonal to wheel load sensitivity and longitudinal tangential force sensitivity) The above-mentioned methods are primarily lateral force calculation methods that utilize pseudoinverse matrices. These methods calculate approximate solutions to simultaneous equations whose solutions are essentially indeterminate so as to minimize the error norm. Rather than aiming to minimize the error norm, the present invention derives an inverse matrix with a structure that is convenient for canceling out cross-sensitivity terms—more specifically, an inverse element that is orthogonal to a certain vector space and is a broadly invertible element of the coefficient matrix of a linear equation—to accurately calculate continuous lateral force and contact position using waveforms obtained from an axially asymmetric bridge circuit.

[0047] (Explanation of derivation of inverse element) First, the derivation of the inverse element will be explained.

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[0048] specifically

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[0049] To guarantee the first property, we consider the constrained optimization problem shown in equation (8).

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[0050] First constraint

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[0051] Differentiating both sides of equation (10) with respect to the vector w gives equation (11).

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[0052] Here, when the first constraint is taken into consideration, equation (14) is obtained.

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[0053] Linear operators

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[0054] Next, the second property,

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[0055] Finally, we consider the sufficiency of the solution to the optimization problem.

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[0056] ((Specific derivation of the inverse element in the continuation process)) The distortion output of the four systems shown in equation (1)

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[0057] Finally, the approximate solution of this equation (23)

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[0058] However, to cancel all cross-sensitivity terms, the four vectors α P (φ),β P (φ),α T (φ),β T It is necessary to determine a vector w that is orthogonal to (φ), and four channels alone do not have enough dimensions.

[0059] Therefore, in reality, an inverse element orthogonal to a vector with a large influence is considered, and calculations are performed that minimize the influence of cross-sensitivity terms.

[0060] Here, examples of each vector (slope and intercept of the cross sensitivity function) in an actual PQ wheelset are shown in Figs. 7 to 10. In Fig. 7, the vector α P The components of (φ) are shown as a function of the circumferential loading position, and in Fig. 8 the vector β P (φ), and in Figure 9, the vector α T (φ), and in Figure 10, the vector β TEach component of (φ) is shown as a function of the circumferential loading position. Here, the unit of the function representing the slope is με / kNmm, while the unit representing the intercept is με / kN, so the units are different. In other words, the degree of influence of the former differs depending on the contact position in the left-right direction.

[0061] As mentioned above, the vector α P (φ) is a vector-valued function of φ, which represents the proportionality coefficient of the strain output per unit wheel load (cross sensitivity) with respect to the lateral contact position y. Vector β P (φ) is a vector-valued function of φ, which represents the intercept of the strain output per unit wheel load (cross sensitivity). Vector α T (φ) is a vector-valued function of φ, which represents the proportionality coefficient of the strain output (cross sensitivity) per unit longitudinal tangential force with respect to the lateral contact position y. Vector β T (φ) is a vector-valued function of φ that represents the intercept of the strain output per unit longitudinal tangential force (cross sensitivity).

[0062] Here, we consider the degree of influence at y=30 mm, which is near the boundary between the straight flange portion and the throat portion.

[0063] First, the proportionality coefficient of cross wheel load sensitivity has a maximum value of approximately 0.03 με / kNmm, and at the y=30mm position, it is approximately 0.9 με / kN. This is approximately six to nine times the maximum value of the intercept of cross wheel load sensitivity (approximately 0.1 to 0.15 με / kN). Similarly, the proportionality coefficient of cross front / rear tangential force sensitivity has a maximum value of approximately 0.025 με / kNmm, and at the y=30mm position, it is approximately 0.75 με / kN, while the intercept is at most 0.05 με / kN. In other words, it can be seen that the effect of a large shift in the contact position toward the flange is greater for the proportionality coefficient than for the intercept. This suggests that, at least for the cross wheel load sensitivity and the proportionality coefficient of cross front / rear tangential force, cancellation should take precedence over the intercept.

[0064] On the other hand, even if we consider an inverse element that cancels out both the wheel load cross sensitivity and the proportionality coefficient of the front and rear tangential forces, the remaining one degree of freedom can be used to cancel out one of the intercepts. However, the intercept of the wheel load cross sensitivity is close to an impulse shape, and even a slight error in the installation of the strain gauges can significantly change its characteristics, so taking this into account in the inverse element could actually worsen the accuracy. As for the intercept of the front and rear tangential force cross sensitivity, the overall absolute value is small and no clear periodicity is observed, so the matrix

number

[0065] [Comparative verification of various continuation processing methods] (Comparison as a weighting function of lateral pressure) A comparison of the weighting functions of each continuation processing method is shown in Figures 11 to 15. (a) Method using the pseudo-inverse matrix of the vector H(φ) (Equation (3), Figure 11). (b) In the method using simultaneous equations (equation (4)) that considers lateral force and contact position, P = 40kN and T = 0kN (Fig. 12). Note that the weighting function shown here is the four components of the pseudo-inverse matrix that represent the weighting related to lateral force, and the function part of φ included on the right side of equation (4) is not reflected. (c) The method using simultaneous equations (equation (4)) that considers lateral force and contact position, with P = 40kN and T = 10kN (Fig. 13). As with (b), the function part of φ included on the right side of equation (4) is not reflected. (d) A method using an inverse element orthogonal to only the proportional coefficient vector of the wheel load cross sensitivity, i.e., d=1, and the vector V=α P (φ) (Figure 14). (e) A method using the inverse element orthogonal to the proportional coefficient vector of each of the wheel load cross sensitivity and the longitudinal tangential force cross proportional sensitivity, that is, when d=2, the vector V=[α P (φ)α T (φ)] (Figure 15).

[0066] In the method using the pseudo-inverse matrix in (a), the pseudo-inverse matrix converts the vector H(φ) into a scalar

number

[0067] In contrast, the method using simultaneous equations (equation (4)) that consider the lateral force and contact position in (b) and (c) results in a complex function shape, and in particular, as in the case of (c) (Fig. 13), its characteristics change significantly depending on the magnitude of the longitudinal tangential force T.

[0068] Regarding the method of (d) using an inverse element orthogonal to only the proportional coefficient vector of the wheel load cross sensitivity (Fig. 14), the shape of the function itself is the same as in the case of (b) (Fig. 12), and it can be seen that (b) and (d) are equivalent in terms of their properties as weighting functions, at least in ideal situations.

[0069] Regarding the method (e) that uses the inverse elements orthogonal to the proportional coefficient vectors of the wheel load cross sensitivity and the front / rear tangential force cross proportional sensitivity (Fig. 15), the function shape itself is basically similar to that of (d) (Fig. 14), but the overall shape is smoothed out.The shape is also significantly different from that of (c), which also takes into account both wheel load and front / rear tangential force.

[0070] (Simulation results of continuous lateral pressure processing) A simulation of the lateral pressure continuity process for the simulated strain waveform was carried out as follows. Using the sensitivity function constructed from the static load test results, a simulated strain waveform is generated for one wheel rotation (i.e., in the range of φ∈[0,2π]) under the assumption that P, T, Q, and y are constant. For example, the output of the bridge circuit for measuring lateral force is calculated using Eq. (1).

number

[0071] The following five continuation processing methods were implemented, including the conventional method. Method 1: A method that uses simultaneous equations that consider lateral pressure and contact position for an axially asymmetric bridge circuit of the shear strain method. Method 2: A method using the pseudoinverse matrix of the vector H(φ) for the bending strain type axisymmetric bridge circuit Method 3: Using the pseudo-inverse matrix of the vector H(φ) for the shear strain type axially asymmetric bridge circuit Method 4: A method using an inverse element orthogonal to only the proportional coefficient vector of the wheel load cross sensitivity for an axially asymmetric bridge circuit of the shear strain method Method 5: A method that uses the inverse element orthogonal to the proportional coefficient vectors of the wheel load cross sensitivity and the front and rear tangential force cross sensitivity for the axisymmetric bridge circuit of the shear strain method.

[0072] 16 to 19 show the results of the continuous processing. Simulated strain waveforms were generated for four different load conditions. Specifically, the wheel load P, lateral force Q, and lateral contact position y were set to 40kN, 30kN, and 30mm, respectively, for all conditions, and four combinations were generated for the conditions when the front and rear tangential force T was not acting and when it was acting at 10kN, and when the circumferential contact position error Δφ was 0rad and 0.05rad.

[0073] The results of these continuation processes are summarized in Tables 1 to 4, which show the errors corresponding to the maximum and minimum lateral forces after continuation processes, as well as the average error per wheel revolution. FIG. 16 shows an example of condition 1: P=40 kN, Q=30 kN, T=0 kN, y=30 mm, Δφ=0 rad (no circumferential contact position error). FIG. 17 shows an example of condition 2: P=40 kN, Q=30 kN, T=0 kN, y=30 mm, Δφ=0.05 rad (with circumferential contact position error). FIG. 18 shows an example of condition 3: P=40 kN, Q=30 kN, T=10 kN, y=30 mm, Δφ=0 rad (no circumferential contact position error). FIG. 19 shows an example of condition 4: P=40 kN, Q=30 kN, T=10 kN, y=30 mm, Δφ=0.05 rad (with circumferential contact position error).

[0074] Conditions in Table 1: P = 40 kN, Q = 30 kN, T = 0 kN, y = 30 mm, Δφ = 0 rad (no circumferential contact position error) [Table 1]

[0075] Conditions in Table 2: P = 40 kN, Q = 30 kN, T = 0 kN, y = 30 mm, Δφ = 0.05 rad (with circumferential contact position error) [Table 2]

[0076] Conditions in Table 3: P = 40 kN, Q = 30 kN, T = 10 kN, y = 30 mm, Δφ = 0 rad (no circumferential contact position error) [Table 3]

[0077] Conditions in Table 4: P = 40 kN, Q = 30 kN, T = 10 kN, y = 30 mm, Δφ = 0.05 rad (with circumferential contact position error) [Table 4]

[0078] First, for all simulated strain waveforms, the error for the maximum value, minimum value, and average value was the largest for the conventional method, Method 2. Most of this error was due to the influence of apparent lateral pressure, with an error of 3.94 kN occurring in the worst case. Methods 1 and 3 to 5 for the shear strain axially asymmetric bridge circuit all have higher accuracy than the conventional method, Method 2. Method 3, which uses a pseudo-inverse matrix, has a smaller error than Method 2, but the average error is still around 2.6 kN.

[0079] Method 1, which uses simultaneous equations that take lateral force and contact position into account, shows excellent performance when the circumferential contact position error Δφ is 0, and has the smallest maximum error, minimum error, and average error of all methods. However, as the circumferential contact position error increases, the error of Method 1 tends to increase. In particular, under conditions where the circumferential contact position error and the front-to-rear tangential force act together (Figure 19 and Table 4), not only does it produce a harmonic fluctuating error, but it also produces an average error of -1.63 kN. This is thought to be because the circumferential contact position error causes an average error in the front-to-rear tangential force.

[0080] In Methods 4 and 5, which use the inverse element orthogonal to the cross sensitivity, calculation errors for at least the wheel load and front / rear tangential force are not propagated to the lateral force calculation, and are therefore suppressed overall. There is not much difference in the magnitude of the errors between Methods 4 and 5, but Method 5 tends to have slightly better accuracy. For example, under conditions where the circumferential contact position error and the effects of the front / rear tangential force overlap (Figure 19 and Table 4), the reduction rates of the absolute error values ​​for Method 5 compared to the conventional method were 81.6% for the error corresponding to the maximum value, 80.2% for the error corresponding to the minimum value, and 99.2% for the average error.

[0081] In this simulation, Method 5 had the highest accuracy, but no significant difference in accuracy was observed between it and Method 4. In addition, Method 4 does not use information on the front-to-rear tangential force cross sensitivity, which has the advantage that the front-to-rear tangential force test, which involves varying the contact position in the left-to-right direction, can be omitted from the certification test. Method 4 is particularly advantageous when the front-to-rear tangential force test is difficult.

[0082] The above results confirm that the continuation method using inverse elements orthogonal to the cross sensitivity is effective in situations where circumferential contact position errors occur due to front-rear tangential force effects or rotary encoders. In particular, because the values ​​of wheel load and front-rear tangential force are not explicitly used in the calculation of lateral force, there is an advantage in that the lateral force can be calculated before these are calculated. This basically eliminates the need for repeated calculations to correct the lateral force cross sensitivity for wheel load measurement bridges that use the offset calculation method for axisymmetric bridge circuits, and allows the calculation process to be completed in a one-way flow.

[0083] (Explanation of contact position continuity processing) Although the continuity processing of lateral pressure has been explained, the continuity processing method using the inverse element orthogonal to the cross sensitivity can also be applied to the continuity processing of the contact position y in the left-right direction.

[0084] This is explained below. One is the vector α P (φ) is the coefficient matrix A, and the vector V is V=[H(φ) α T (φ)]

number

number

[0085] Alternatively, the intercept for the wheel load cross sensitivity can be left on the right side,

number

[0086] The method using this equation (26) was designated as Method 7, the method using equation (27) as Method 8, and the method using simultaneous equations that take into account the lateral pressure and contact position for the axisymmetric bridge circuit of the shear strain method as Method 6, and the accuracy of the continuity processing of the contact position was evaluated.

[0087] The verification results are shown in Figures 20 to 23. Tables 5 to 8 show the errors corresponding to the maximum and minimum contact positions after the continuation process, as well as the average error per wheel revolution.

[0088] Conditions: P = 40 kN, Q = 30 kN, T = 0 kN, y = 30 mm, Δφ = 0 rad (no circumferential contact position error) [Table 5]

[0089] Conditions: P = 40 kN, Q = 30 kN, T = 0 kN, y = 30 mm, Δφ = 0.05 rad (with circumferential contact position error) [Table 6]

[0090] Conditions: P = 40 kN, Q = 30 kN, T = 10 kN, y = 30 mm, Δφ = 0 rad (no circumferential contact position error) [Table 7]

[0091] Conditions: P = 40 kN, Q = 30 kN, T = 10 kN, y = 30 mm, Δφ = 0.05 rad (with circumferential contact position error) [Table 8]

[0092] In Method 6, which uses simultaneous equations that take into account lateral pressure and contact position, the error in Method 6 was significantly larger when the error in the circumferential contact position was 0.05 rad. On the other hand, in methods 7 and 8, which use the inverse elements orthogonal to the lateral pressure sensitivity and the longitudinal tangential force cross sensitivity, the error does not increase significantly even when an error in the circumferential contact position occurs. In particular, it was found that the absolute value of the average error was kept to less than 0.5 mm in method 8, which takes into account the intercept of the wheel load cross sensitivity. Therefore, a method using the concept of orthogonal inverse elements is also effective for calculating the contact position in the left-right direction.

[0093] In this way, the method of calculating lateral pressure by deriving the inverse of the lateral pressure sensitivity vector that is orthogonal to the proportional coefficient vector of wheel load cross sensitivity and the front-rear tangential force cross sensitivity vector for the output of the shear strain type axisymmetric bridge circuit has a small average error in lateral pressure, and the method of calculating contact position by deriving the inverse of the proportional coefficient vector of wheel load cross sensitivity that is orthogonal to the lateral pressure sensitivity vector and the front-rear tangential force cross sensitivity vector has a small average error in contact position.

[0094] (Addendum) The contents described in the above embodiment can be understood, for example, as follows.

[0095] (1) 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 to 8B that penetrate the plate portion 130 in the direction of the rotation axis of the wheel 100 and are attached to the inner surfaces of holes arranged around the rotation axis, and detect shear strain of the plate portion caused by the lateral pressure; a calculation unit 400 that continuously calculates the lateral pressure or the contact position based on an output of the bridge circuit that is asymmetric with respect to the rotation center axis, the bridge circuit being configured with the strain gauges; Equipped with the output sensitivity characteristics of the bridge circuit, which correspond to the wheel load between the wheel and the rail and the longitudinal tangential force of the wheel, change with the rotation of the wheel; The calculation unit 400 calculates the lateral pressure based on the inverse of the lateral pressure sensitivity vector that is orthogonal to the proportional coefficient vector of the wheel load cross sensitivity, which is determined by the characteristics of the output sensitivity of the bridge circuit (Equation (24)). It is characterized by:

[0096] If it is possible to determine the inverse of the lateral pressure sensitivity vector that is orthogonal to only the proportional coefficient vector of the wheel load cross sensitivity, the component of the wheel load cross sensitivity that is proportional to the amount of contact position movement from the center of the wheel tread can be removed. In other words, it is possible to calculate the lateral pressure from which the component of the output sensitivity of the bridge circuit that is proportional to the amount of contact position movement has been removed.

[0097] (2) The intercept of the wheel load cross sensitivity is not included. The above-described measuring device can derive the inverse element of the lateral pressure sensitivity vector without satisfying orthogonality to the intercept of the wheel load cross sensitivity.

[0098] By doing so, it is possible to consider an inverse element that is orthogonal to a vector with a large influence, and perform calculations that minimize the influence of cross-sensitivity terms (FIGS. 7 to 10).

[0099] (3) The lateral force can be calculated based on an inverse element orthogonal to the proportionality coefficient vector of the wheel load cross sensitivity and the front-rear tangential force cross sensitivity.

[0100] By calculating the lateral force based on the inverse element orthogonal to the proportionality coefficient vectors of the wheel load cross sensitivity and the front-rear tangential force cross sensitivity, the lateral force can be calculated with greater accuracy, particularly in situations where front-rear tangential forces are acting and a circumferential contact position error occurs (FIGS. 16 to 19). [Explanation of symbols]

[0101] 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 Slip Ring Device 300 Strain signal processing section 400 Arithmetic section

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 continuously calculates the lateral force or the contact position based on an output of the bridge circuit, which is configured of the strain gauges and is asymmetric with respect to the rotation center axis; and Equipped with an output sensitivity characteristic of the bridge circuit according to a wheel load between the wheel and the rail and a longitudinal tangential force of the wheel changes with rotation of the wheel; The calculation unit The lateral pressure is calculated based on an inverse element of a lateral pressure sensitivity vector according to the output sensitivity characteristics of the bridge circuit, which is orthogonal to a proportional coefficient vector of wheel load cross sensitivity. A measuring device characterized by:

2. 2. The measuring device according to claim 1, When deriving the inverse element of the lateral pressure sensitivity vector, orthogonality to the intercept of the wheel load cross sensitivity is not satisfied. A measuring device characterized by:

3. 2. The measuring device according to claim 1, the calculation unit calculates the lateral pressure based on an inverse of the lateral pressure sensitivity vector, the inverse being orthogonal to proportionality coefficient vectors of the wheel load cross sensitivity and the front-rear tangential force cross sensitivity, each determined by an output sensitivity characteristic of the bridge circuit. Measuring equipment.

4. 4. The measuring device according to claim 3, the calculation unit further calculates the contact position based on an inverse of a proportionality coefficient vector of the wheel load cross sensitivity, the inverse vector being orthogonal to the proportionality coefficient vector of the front / rear tangential force cross sensitivity and the lateral pressure sensitivity vector. A measuring device characterized by:

5. 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, 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 continuously calculates the lateral force or the contact position based on an output of the bridge circuit, which is configured of the strain gauges and is asymmetric with respect to the rotation center axis; and Equipped with an output sensitivity characteristic of the bridge circuit according to a wheel load between the wheel and the rail and a longitudinal tangential force of the wheel changes with rotation of the wheel; the calculation unit calculates the lateral pressure based on a lateral pressure sensitivity vector inverse that is orthogonal to a proportional coefficient vector of wheel load cross sensitivity, the inverse being determined by the output sensitivity characteristics of the bridge circuit. A measuring method characterized by:

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