On-board device and determination method

Abstract

To improve accuracy in detecting magnets installed on a track without error in an on-board device.SOLUTION: Permanent magnets 7 are installed in installation positions predetermined on a track 5 so that different polarities are positioned in a direction along the track 5 with a surface on which the different polarities are arranged as a top surface. An on-board device 1 determines whether or not the installation positions of the permanent magnets 7 are passed by: detecting magnetic field distribution based on respective detection values of a plurality of magnetic sensor elements arranged in a prescribed position relation of a magnetic sensor unit 10; carrying out a space filter process including at least a derivative element to the detected magnetic field distribution; and comparing a prescribed reference magnetic field distribution with the magnetic field distribution having been subjected to the space filter process.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an on-board device and the like. [Background technology]

[0002] In railways, on-board train position detection techniques are becoming increasingly common, primarily for the purpose of simplifying ground equipment. A common on-board train position detection method is to calculate the train's running distance by integrating train speed information acquired using a tachograph, pulse generator, speed sensor, etc., and then detect the train's position. Because the acquired speed information is likely to contain errors, from a safety perspective, it is necessary to periodically reset the train position error by using other position correction equipment, such as a Global Navigation Satellite System (GNSS) or an Automatic Train Stop (ATS) ground coil. In recent years, a method has been proposed in which a position correction magnet is installed on the track, and an on-board device detects the magnet to detect the absolute position and reset the train position error (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-170810 Summary of the Invention [Problem to be solved by the invention]

[0004] Meanwhile, railways often contain strongly magnetized objects such as iron bridges and rails, as well as train control currents flowing through the rails. The presence of such objects near the position correction magnets can lead to false detection. The on-board device detects the magnetic field generated by the magnets using magnetic sensors, but if there are magnetized objects or train control currents flowing through the rails, the sensors will also detect the magnetic fields generated by these objects. This can result in situations where the device fails to detect the magnets or erroneously detects magnets that do not exist. This problem is not limited to magnets used for position correction.

[0005] The problem to be solved by the present invention is to improve the accuracy with which an on-board device can detect magnets installed on a track without error. [Means for solving the problem]

[0006] The first invention to solve the above problem is: An on-board device mounted on a vehicle running on a track on which magnets are installed at predetermined installation positions, a magnetic sensor unit having a plurality of magnetic sensor elements arranged in a predetermined positional relationship to detect a magnetic field generated by the magnet when the magnet passes through the installation position; a processing unit that determines whether or not the magnetic sensor unit has passed the installation position based on the detection value of the magnetic sensor unit; Equipped with the magnet is arranged such that the surface on which the different magnetic poles are arranged faces upward, and the different magnetic poles are positioned in a direction along the trajectory; The processing unit a detection unit that detects a magnetic field distribution based on the detection values ​​of the magnetic sensor elements; a spatial filter processing unit that performs spatial filtering including at least a differential element on the detected magnetic field distribution; a determination unit that determines whether the magnetic field distribution after spatial filtering has passed through the installation position by comparing a predetermined reference magnetic field distribution with the magnetic field distribution after spatial filtering; having It is an on-board device.

[0007] Other inventions include: A method for determining whether an on-board device mounted on a vehicle running on a track with a magnet installed at a predetermined installation position, the on-board device including a magnetic sensor unit having a plurality of magnetic sensor elements arranged in a predetermined positional relationship to detect a magnetic field generated by the magnet when the vehicle passes the installation position, based on a detection value of the magnetic sensor unit, comprising: the magnet is arranged such that the surface on which the different magnetic poles are arranged faces upward, and the different magnetic poles are positioned in a direction along the track; detecting a magnetic field distribution based on the detection values ​​of the magnetic sensor elements; performing a spatial filtering process including at least a differential element on the detected magnetic field distribution; determining whether the magnetic field distribution after spatial filtering has passed through the installation position by comparing a predetermined reference magnetic field distribution with the spatially filtered magnetic field distribution; A determination method including the above may be configured.

[0008] According to the first invention and others, it is possible to improve the accuracy with which an on-board device can detect a magnet installed on a track without error. That is, the on-board device determines that a train has passed the installation position of the magnet by comparing a magnetic field distribution based on the detection values ​​of each magnetic sensor element, which has been spatially filtered, with a predetermined reference magnetic field distribution. The magnet is arranged so that the surface on which different magnetic poles are arranged faces upward, and the different magnetic poles are positioned in a direction along the track. Therefore, the magnetic field distribution detected by each of the multiple magnetic sensor elements moving in a direction along the track is a magnetic field distribution that exhibits abrupt changes in the magnetic field at locations corresponding to the spatially different magnetic poles.

[0009] By applying a spatial filter process that includes at least a differential element to such a magnetic field distribution, it becomes possible to capture spatially steep changes in the magnetic field. For example, magnetic fields generated by magnetized objects located relatively far from the magnetic sensor unit or currents flowing in the rails may be larger in magnitude than magnets, but are detected as magnetic field distributions that change slowly in space. This allows the on-board device to accurately detect magnets, distinguishing them from other magnetic field-generating objects, and determine whether the train has passed the location where the magnet is installed.

[0010] The second invention is the above-mentioned invention. the spatial filter processing unit performs the spatial filter processing including at least a second-order differential element. It is an on-board device.

[0011] According to the second aspect of the present invention, spatially steep magnetic field changes can be more reliably detected, thereby further improving the accuracy of magnet detection.

[0012] The third invention is the above-mentioned invention, The magnetic sensor unit has the magnetic sensors arranged in a plane along the front-rear and left-right directions of the vehicle. It is an on-board device.

[0013] According to the third aspect of the present invention, it becomes possible to detect the magnetic field generated by the magnet as a two-dimensional magnetic field distribution, which is suitable for spatial filtering.

[0014] A fourth aspect of the present invention is the above-mentioned invention, The magnets include a plurality of types of magnets that differ in any one of size, installation orientation, and magnetic pole arrangement pattern, a type of the magnet to be installed on the track is determined for each installation position at which the magnet is installed, The reference magnetic field distribution includes a reference magnetic field distribution for each type of magnet, the determination unit compares the magnetic field distribution subjected to the spatial filtering process by the spatial filtering processing unit with reference magnetic field distributions for each type of magnet, and determines the type of magnet installed at the installation position through which the magnetic field distribution passes. It is an on-board device.

[0015] According to the fourth invention, by associating the type of magnet with the installation location, the on-board device can determine the type of magnet that has passed the installation location, determine its installation location, and, for example, correct the train position.

[0016] The fifth invention is the above-mentioned invention, the magnetic sensor element has a plurality of detection axes; the detection unit detects the magnetic field distribution for each of the detection axes, the reference magnetic field distribution includes a reference magnetic field distribution for each of the detection axes, the determination unit compares, for each of the detection axes, a reference magnetic field distribution of the detection axis with the magnetic field distribution of the detection axis that has been subjected to the spatial filtering process; It is an on-board device.

[0017] According to the fifth invention, since the magnetic field generated by a magnet is a magnetic field distribution in three-dimensional space, by comparing the magnetic field distribution detected for each detection axis of a magnetic sensor element having multiple detection axes with a reference magnetic field distribution, the magnetic field generated by the magnet can be detected more accurately, and it can be determined with higher accuracy whether or not the magnet has passed through the installation position. [Brief explanation of the drawings]

[0018] [Figure 1] An example of application of on-board equipment. [Figure 2] 1 shows an example of the configuration of the magnetic sensor unit. [Figure 3] FIG. 1 is an explanatory diagram of how to express magnetic field distribution. [Figure 4] An example of a type of permanent magnet. [Figure 5] An example of a type of permanent magnet. [Figure 6] An example of a type of permanent magnet. [Figure 7] An example of a type of permanent magnet. [Figure 8] An example of a type of permanent magnet. [Figure 9] An example of the detected magnetic field distribution. [Figure 10] An example of spatial filter coefficients. [Figure 11] 10 is an example of a spatially filtered magnetic field distribution corresponding to the detected magnetic field distribution in FIG. 9 . [Figure 12] An example of the detected magnetic field distribution. [Figure 13] 13 is an example of a spatially filtered magnetic field distribution corresponding to the detected magnetic field distribution of FIG. 12. [Figure 14] Functional configuration diagram of the on-board control device. [Figure 15] An example of detected data. [Figure 16] An example of installed magnet data. [Figure 17] 10 is a flowchart of a determination process. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Note that the forms to which the present invention can be applied are not limited to the following embodiments. In addition, in the description of the drawings, the same elements are given the same reference numerals.

[0020] [Overall configuration] FIG. 1 is a diagram illustrating an example of application of an on-board device according to this embodiment. As shown in FIG. 1, the on-board device 1 is mounted on a railway vehicle 3 traveling on a track 5, and includes a magnetic sensor unit 10 and an on-board control device 30. A plurality of permanent magnets 7 are installed on the track 5 at predetermined installation positions for each type. In this embodiment, the permanent magnets 7 are installed between the left and right rails. The type of permanent magnet 7 is determined by its size, installation orientation, and magnetization pattern, which is the arrangement pattern of the magnetic poles.

[0021] The magnetic sensor unit 10 is installed on the bottom of the railway vehicle 3 or on a bogie at a position where it can detect the permanent magnet 7 when the railway vehicle passes the installation position of the permanent magnet 7 installed on the track 5. Preferably, the magnetic sensor unit 10 is installed at a position where it faces the permanent magnet 7 when the railway vehicle passes the installation position of the permanent magnet 7.

[0022] The on-board control device 30 constantly calculates the running position of the railway vehicle 3 by integrating speed information acquired using a tachograph, a pulse generator, etc. In this embodiment, the installation position of the permanent magnet 7 is determined in advance, and therefore, when the permanent magnet 7 is detected by the magnetic sensor unit 10, the on-board control device 30 can correct the calculated running position using the detected installation position of the permanent magnet 7.

[0023] FIG. 2 is a diagram illustrating an example of the configuration of the magnetic sensor unit 10. FIG. 2 shows a schematic plan view of the magnetic sensor unit 10 as viewed from above. As shown in FIG. 2, the magnetic sensor unit 10 has a plurality of magnetic sensor elements 12 arranged in a plane facing the track 5. The example in FIG. 2 shows the magnetic sensor unit 10 having a total of 16 magnetic sensor elements A to P arranged in a plane, four rows in the left-right direction and four rows in the front-rear direction of the railway vehicle 3. The spacing between adjacent magnetic sensor elements 12 is preferably such that the magnetic sensor elements 12 do not overlap each other, and the spacing between the centers of the magnetic sensor elements 12 is preferably within 150 mm in both the left-right direction and the front-rear direction. Of course, the number and arrangement of the magnetic sensor elements 12 included in the magnetic sensor unit 10 are not limited to this.

[0024] The magnetic sensor element 12 is an element that detects a magnetic field and outputs a current or voltage corresponding to the magnitude and direction of the magnetic field as a detection value. The magnetic sensor element 12 is, for example, a Hall element, a magnetoresistive element (MR element), a magnetic impedance element (MI element), a flux-gate sensor, or the like.

[0025] The magnetic sensor element 12 is a three-axis sensor having three detection axes (X-axis, Y-axis, and Z-axis), and is arranged so that the X-axis corresponds to the longitudinal direction of the railway vehicle 3, the Y-axis corresponds to the lateral direction of the railway vehicle 3, and the Z-axis corresponds to the vertical direction of the railway vehicle 3. The detection values ​​of the magnetic sensor element 12 are output to the on-board control device 30. The on-board control device 30 detects the magnetic field distribution based on the detection values ​​of each magnetic sensor element 12.

[0026] FIG. 3 is a diagram illustrating how the magnetic field distribution is represented in this embodiment. The magnetic sensor element 12 is a triaxial sensor having three detection axes, and the on-board control device 30 detects the magnetic field distribution for each of the three detection axes based on the detection values ​​of the magnetic sensor element 12 for that detection axis. The magnetic field distribution for one detection axis is represented as a two-dimensional array in which the detection values ​​of each magnetic sensor element 12 for that detection axis are elements I(i, j). The positive and negative detection values ​​of the magnetic sensor element 12 represent the direction of the magnetic field, and the magnitude (absolute value) represents the magnitude (strength) of the magnetic field. The two-dimensional array corresponds to the arrangement positions of the magnetic sensor elements 12 in the magnetic sensor unit 10, with the longitudinal direction (travel direction) of the railway vehicle 3 corresponding to the i direction of the two-dimensional array, and the lateral direction (sleeper direction) of the railway vehicle 3 corresponding to the j direction.

[0027] Multiple types of permanent magnets 7 are installed on the track 5 at installation positions that are predetermined for each type. The type of permanent magnet 7 is determined by its size, installation orientation, and magnetization pattern, which is the arrangement pattern of the magnetic poles. Different types of permanent magnets 7 generate different magnetic fields (generated magnetic fields), and therefore the magnetic field distribution detected by the magnetic sensor unit 10 mounted on the railway vehicle 3 when the railway vehicle 3 passes the installation position of the permanent magnet 7 differs. Using this, the on-board control device 30 determines the type of permanent magnet 7 detected based on the magnetic field distribution detected by the magnetic sensor unit 10. The running position is then corrected using the installation position of the determined type of permanent magnet 7.

[0028] 4 to 7 are diagrams showing examples of types of permanent magnets 7. As shown in Fig. 4 to 7, permanent magnets 7a to 7d are configured to have a substantially rectangular shape when viewed from above. Permanent magnets 7a to 7d are configured as a single magnet with different magnetization patterns depending on the location, but specifically, they can be configured by combining multiple magnet pieces, for example.

[0029] The permanent magnet 7a shown in Fig. 4 has a magnetization pattern in which the magnetization is such that the magnetic poles in diagonal view are the same when viewed from above. The installation orientation of the permanent magnet 7a is such that the magnetic poles at the upper left and lower right of the top surface in Fig. 4 are N poles, and the magnetic poles at the upper right and lower left are S poles. In other words, the installation orientation is such that the magnetic poles (N pole and S pole) differ in the direction along the track 5 (front-back direction, X-axis direction).

[0030] Since the permanent magnet 7 generates a magnetic flux that flows from the north pole to the south pole, even if a permanent magnet 7 (e.g., permanent magnet 7a) with the same magnetization pattern is placed, if the installation orientation is different, the magnetic field distribution (detected magnetic field distribution) detected by the magnetic sensor unit 10 will be different. Therefore, permanent magnets 7 with the same magnetization pattern but different installation orientations can be treated as different types of permanent magnets 7. For example, permanent magnet 7b shown in FIG. 5 has the same magnetization pattern as permanent magnet 7a, but is placed in an installation orientation where the magnetic poles on the upper left and lower right of the top surface are south poles and the magnetic poles on the upper right and lower left of the top surface are north poles, that is, rotated 90 degrees around the Z axis from permanent magnet 7a, and is treated as a different type of permanent magnet from permanent magnet 7a.

[0031] 6 has a magnetization pattern in which the magnetic poles in a top view are the same alternately along the front-to-back direction (X-axis direction). The installation orientation of the permanent magnet 7c in FIG. 6 is such that the first and third magnetic poles from the front in the direction along the track (front-to-back direction) are N poles, and the second and fourth magnetic poles from the front are S poles.

[0032] Furthermore, permanent magnet 7d shown in FIG. 7 has the same magnetization pattern as permanent magnet 7c, but is oriented such that the first and third magnetic poles from the front in the direction along the track (front-rear direction) are south poles and the second and fourth magnetic poles from the front are north poles, that is, it is arranged in an orientation rotated 180 degrees around the Z axis from permanent magnet 7c, and is a different type from permanent magnet 7c.

[0033] The shape of the permanent magnet 7 is not limited to a rectangular shape when viewed from above, and may be other shapes such as a circle. For example, a magnetization pattern may be used in which different magnetic poles are arranged in a concentric circle shape, as in the permanent magnet 7e shown in Fig. 8.

[0034] The type of permanent magnet 7 is determined by comparing the magnetic field distribution (hereinafter referred to as the "detected magnetic field distribution") detected by the magnetic sensor unit 10 with a predetermined reference magnetic field distribution corresponding to the type of permanent magnet 7 after a predetermined spatial filtering process (hereinafter referred to as the "filtered magnetic field distribution").

[0035] The reference magnetic field distribution is a magnetic field distribution that serves as a reference for determining whether the railway vehicle 3 has passed the installation position of the corresponding type of permanent magnet 7. Specifically, it is determined based on the magnetic field distribution after the above-mentioned spatial filtering process is performed on the magnetic field distribution that would be detected by the magnetic sensor unit 10 when the railway vehicle 3 passes the installation position of the permanent magnet 7. The magnetic field distribution that would be detected by the magnetic sensor unit 10 may be, for example, the magnetic field distribution detected when the railway vehicle 3 actually travels on the track 5 after the permanent magnet 7 is installed on the track 5. Alternatively, since the magnetic field distribution detected by the magnetic sensor unit 10 is determined by the relative positional relationship between the permanent magnet 7 and the magnetic sensor unit 10, it can be determined from experimental results in a laboratory or factory or by computer simulation. Furthermore, since the magnetic sensor element 12 is a three-axis sensor and the magnetic field distribution is detected for each detection axis, the reference magnetic field distribution is also determined for each detection axis.

[0036] The spatial filtering of the detected magnetic field distribution is spatial filtering having at least a differential element. Spatial filtering having a second-order differential element is more preferable. The permanent magnet 7 is installed with the surface on which the different magnetic poles are arranged facing upward. By installing the permanent magnet 7 in this manner, the magnetic field distribution detected by each of the magnetic sensor elements 12 of the magnetic sensor unit 10 facing the permanent magnet 7 exhibits a sharp change in the magnetic field at locations corresponding to the spatially different magnetic poles, i.e., a magnetic field distribution with a high spatial frequency. By performing spatial filtering of such a magnetic field distribution having at least a differential element, it is possible to detect a sharp change in the magnetic field. Furthermore, since the permanent magnet 7 is installed in an orientation in which the different magnetic poles are located along the track 5, when the railway vehicle 3 passes the installation position of the permanent magnet 7 along the track 5, the magnetic field distribution in which the magnetic field generated by the permanent magnet 7 exhibits a sharp change in space is detected continuously in time.

[0037] The type of permanent magnet 7 is determined by calculating a correlation coefficient between the magnetic field distribution (filtered magnetic field distribution) after spatial filtering of the detected magnetic field when passing through the installation position and a reference magnetic field distribution associated with the type of permanent magnet 7. The magnetic field distribution is represented by the detection values ​​of the multiple magnetic sensor elements 12 for each detection axis of the magnetic sensor elements 12 (see Figure 3). Therefore, for each detection axis, the correlation coefficient between the magnetic field distribution (filtered magnetic field distribution) after spatial filtering of the detected magnetic field distribution for that detection axis and the reference magnetic field distribution is calculated. The correlation coefficient between the filtered magnetic field distribution for one detection axis and the reference magnetic field distribution is calculated as a normalized cross-correlation coefficient according to the following equation (1) using the values ​​of each element of the filtered magnetic field distribution and the reference magnetic field distribution.

number

[0038] In equation (1), "I(i,j)" is the value of an element of the filtered magnetic field distribution, and "I a " is the average value of each element I(i,j) of the filtered magnetic field distribution, "T(i,j)" is the value of the element of the reference magnetic field distribution, and "Ta " is the average value of each element T(i,j) of the reference magnetic field distribution, and "σ I " is the standard deviation of each element I(i,j) of the filtered magnetic field distribution, and "σ T " is the standard deviation of each element T(i,j) of the reference magnetic field distribution.

[0039] The correlation coefficient is a value in the range of "-1.0 to 1.0", with "1.0" representing a perfect match. If the correlation coefficients for all (three) detection axes are equal to or greater than a predetermined threshold (e.g., "0.9"), the filtered magnetic field distribution is determined to match the reference magnetic field distribution. Alternatively, the average or sum of the correlation coefficients for each detection axis may be calculated as a comprehensive correlation coefficient, and the filtered magnetic field distribution may be determined to match the reference magnetic field distribution if this comprehensive correlation coefficient is equal to or greater than a predetermined threshold (e.g., "0.9" if the average of the correlation coefficients is the comprehensive correlation coefficient, or "2.7" if the sum of the correlation coefficients is the comprehensive correlation coefficient). A positive correlation coefficient indicates the same magnetic field, while a negative correlation coefficient indicates opposite magnetic fields. A value of "-1.0" indicates that the magnetic fields are the same in magnitude (absolute value) but opposite in magnetic field.

[0040] Incidentally, when a railway vehicle 3 traveling on the track 5 passes the installation position of a permanent magnet 7, it gradually approaches the installation position of the permanent magnet 7 from just before the installation position of the permanent magnet 7, and then moves away after passing by. For this reason, the on-board control device 30 repeatedly determines at predetermined time intervals (e.g., intervals of about several milliseconds) whether the magnetic field distribution (filtered magnetic field distribution) obtained after spatial filtering of the magnetic field distribution detected by the magnetic sensor unit 10 (detected magnetic field distribution) matches each of the reference magnetic field distributions defined for each type of permanent magnet 7. As a result, it is expected that as the railway vehicle 3 approaches the installation position of the permanent magnet 7, the correlation coefficient with the reference magnetic field distribution for one type of permanent magnet 7 gradually approaches "1.0."

[0041] For this reason, for example, when it is determined that the filtered magnetic field distribution of the detected magnetic field distribution detected in time series matches the reference magnetic field distribution for one type for a predetermined number of times or more consecutively, it is determined that the permanent magnet 7 of that type has been detected. When it is determined that the permanent magnet 7 has been detected, the on-board control device 30 then determines the timing at which the installation position of the permanent magnet 7 was passed in order to correct the running position calculated on the train. For example, the detection timing of the detected magnetic field distribution that is most compatible with the reference magnetic field distribution defined for the detected type of permanent magnet 7 (e.g., has the highest correlation coefficient) is determined as the passing timing of the installation position of the permanent magnet 7. The running position calculated at this passing timing is corrected to the installation position of the permanent magnet 7. Note that the installation position of the permanent magnet 7 is, for example, the position corresponding to the center of the rectangular shape of the permanent magnet 7 when viewed from above.

[0042] FIG. 9 is an example of a detected magnetic field distribution when passing through the installation position of the permanent magnet 7a of the type shown in FIG. 4. However, there are no other objects that generate a magnetic field near the installation position of the permanent magnet 7a, and only the magnetic field generated by the permanent magnet 7a is detected. This example will be referred to below as the "detected magnetic field distribution of only the permanent magnet 7a." FIG. 10 is an example of spatial filter coefficients used in spatial filtering. And FIG. 11 is a filtered magnetic field distribution, which is the magnetic field distribution after spatial filtering of the detected magnetic field distribution shown in FIG. 9 using the spatial filter coefficients shown in FIG. 10. This example will be referred to below as the "filtered magnetic field distribution of only the permanent magnet 7a."

[0043] The detected magnetic field distribution shown in FIG. 9 is a magnetic field distribution detected by a magnetic sensor unit 10 having a total of 36 magnetic sensor elements 12, arranged in six columns in the left-right direction and six columns in the front-back direction. Therefore, the detected magnetic field distribution is expressed as a two-dimensional array (matrix) of six rows and six columns. Then, as spatial filtering processing for the detected magnetic field distribution, a convolution operation is performed on the detected magnetic field distribution with spatial filter coefficients. Here, spatial filtering processing including a second-order differential element is performed, and the spatial filter coefficients are set to a two-dimensional matrix of three rows and three columns, for example, as shown in FIG. 10. Therefore, the filtered magnetic field distribution, which is the magnetic field distribution after spatial filtering processing, is a two-dimensional matrix of four rows and four columns, as shown in FIG. 11.

[0044] For comparison, FIG. 12 shows an example of a magnetic field distribution (detected magnetic field distribution) detected when a large current for train control is flowing through the rail near the installation position of the permanent magnet 7a. When a railway vehicle 3 passes the installation position of the permanent magnet 7a, the magnetic field distribution (detected magnetic field distribution) detected by the magnetic sensor unit 10 mounted on the railway vehicle 3 includes not only the magnetic field generated by the permanent magnet 7a but also a magnetic field generated by the large current flowing through the nearby rail in a superimposed manner. This example will be referred to below as the "detected magnetic field distribution of the permanent magnet 7a and the large current." FIG. 13 shows the magnetic field distribution (filtered magnetic field distribution) after spatial filtering by convolving the detected magnetic field distribution shown in FIG. 12 with the spatial filter coefficients shown in FIG. 10. This example will be referred to below as the "filtered magnetic field distribution of the permanent magnet 7a and the large current."

[0045] The detected magnetic field distribution for the permanent magnet 7a alone shown in Figure 9 reveals that the magnetic field changes sharply spatially. For example, the matrix elements (corresponding to the detection values ​​of one magnetic sensor element 12) in each column of the first row repeatedly increase and decrease in value, indicating a high spatial frequency. In contrast, the detected magnetic field distribution for the permanent magnet 7a and large current shown in Figure 12 reveals that the magnetic field generated by the large current is larger than that generated by the permanent magnet 7a and is dominant in the detected magnetic field distribution. This detected magnetic field distribution also reveals that the spatial magnetic field changes monotonically. The matrix elements in each column for each row decrease monotonically, indicating a low spatial frequency. Because the rail through which the large current flows, generating the dominant magnetic field, is relatively far from the magnetic sensor unit 10 compared to the permanent magnet 7a, the detected magnetic field distribution is thought to exhibit gradual spatial magnetic field changes. In addition, since the correlation coefficient between the detected magnetic field distribution of the permanent magnet 7a shown in Figure 9 and the detected magnetic field distribution of the permanent magnet 7a and large current shown in Figure 12 is very small, at approximately 0.16, it is difficult to determine the passage of the installation position of the permanent magnet 7a from the detected magnetic field distribution shown in Figure 12.

[0046] On the other hand, when the filtered magnetic field distribution of the permanent magnet 7a shown in Fig. 11 is compared with the filtered magnetic field distribution of the permanent magnet 7a and large current shown in Fig. 13, the arrangement of each matrix element is similar, and the correlation coefficient is approximately 1.00, which is almost the maximum value. Therefore, by using the filtered magnetic field distribution of the permanent magnet 7a shown in Fig. 11 as the reference magnetic field distribution of the permanent magnet 7a, it becomes possible to determine with high accuracy that the permanent magnet 7a has passed through the installation position, even if there is another object that generates a magnetic field near the installation position of the permanent magnet 7a.

[0047] [Function Configuration] Fig. 14 is a block diagram showing the functional configuration of the on-board control device 30. According to Fig. 14, the on-board control device 30 includes an operation unit 102, a display unit 104, a sound output unit 106, a communication unit 108, a processing unit 200, and a storage unit 300, and can be configured as a type of computer.

[0048] The operation unit 102 is realized by an input device such as a button switch, a touch panel, or a keyboard, and outputs an operation signal corresponding to the operation performed to the processing unit 200. The display unit 104 is realized by a display device such as an LCD (Liquid Crystal Display) or a touch panel, and displays various types of information corresponding to display signals from the processing unit 200. The sound output unit 106 is realized by a sound output device such as a speaker, and outputs various types of sound corresponding to sound signals from the processing unit 200. The communication unit 108 is realized by a wired or wireless communication device, and communicates with external devices via a given communication network.

[0049] The processing unit 200 is realized by an arithmetic device such as a CPU (Central Processing Unit), and issues instructions and transfers data to each unit constituting the on-board control device 30 based on programs, data, etc. stored in the storage unit 300, thereby performing overall control of the on-board control device 30. Furthermore, the processing unit 200 executes a determination program 302 stored in the storage unit 300, thereby functioning as each of the functional blocks of a traveling position calculation unit 202, a traveling position correction unit 204, a detection unit 206, a spatial filter processing unit 208, and a determination unit 210. However, these functional blocks can also be configured as independent arithmetic circuits using an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), etc.

[0050] The running position calculation unit 202 constantly calculates the running position of the railway vehicle 3. Specifically, for example, the running position is constantly calculated by integrating the running distance from a given starting position using speed information obtained from a rotation detection signal from a tachograph or pulse generator attached to the axle.

[0051] The running position correction unit 204 corrects the running position calculated by the running position calculation unit 202 using the installation position of the permanent magnet 7 of the type determined by the determination unit 210. Specifically, the timing at which it is determined that the magnetic field distribution detected by the detection unit 206 (detected magnetic field distribution) matches the reference magnetic field distribution corresponding to the installation position of the permanent magnet 7 of the type determined by the determination unit 210 is set as the passing timing of that installation position. Then, the running position calculated at that passing timing is updated with that installation position, thereby correcting the running position.

[0052] The detection unit 206 detects the magnetic field distribution based on the detection values ​​of the magnetic sensor elements 12 for each of the multiple detection axes of the magnetic sensor elements 12 of the magnetic sensor unit 10 .

[0053] Specifically, the magnetic field distribution for one detection axis is expressed as a two-dimensional array in which the detection value of each magnetic sensor element 12 for that detection axis is element I(i,j). The two-dimensional array corresponds to the arrangement positions of the magnetic sensor elements 12 in the magnetic sensor unit 10, with the longitudinal direction (travel direction) of the railway vehicle 3 corresponding to the i direction of the two-dimensional array and the lateral direction (sleeper direction) of the railway vehicle 3 corresponding to the j direction (see FIG. 3). The magnetic field distribution detected by the detection unit 206 is included in the detection data 330 and accumulated and stored.

[0054] The spatial filtering unit 208 performs spatial filtering including at least a differential element on the magnetic field distribution detected by the detection unit 206. Alternatively, spatial filtering including at least a second-order differential element may be performed.

[0055] The spatial filter coefficients used in the spatial filtering process are stored as spatial filter coefficient data 320. Furthermore, the magnetic field distribution after spatial filtering by the spatial filtering processor 208 (filtered magnetic field distribution) is included in the detection data 330 and is accumulated and stored.

[0056] The determination unit 210 determines whether the track 5 has passed through an installation position of a permanent magnet 7 by comparing a predetermined reference magnetic field distribution with the magnetic field distribution spatially filtered by the spatial filter processing unit 208. There are multiple types of permanent magnets 7 that differ in any of size, installation orientation, and magnetic pole arrangement pattern. The type of permanent magnet 7 to be installed on the track 5 is determined for each installation position at which the permanent magnet 7 is installed, and the reference magnetic field distribution includes a reference magnetic field distribution for each type of permanent magnet 7. The determination unit 210 compares the magnetic field distribution spatially filtered by the spatial filter processing unit 208 with each reference magnetic field distribution for each magnet type to determine the type of permanent magnet 7 installed at the installation position through which the track 5 passes. In addition, the reference magnetic field distribution includes a reference magnetic field distribution for each detection axis, and the determination unit 210 compares, for each detection axis, the reference magnetic field distribution for that detection axis with the magnetic field distribution for that detection axis spatially filtered.

[0057] Specifically, at predetermined time intervals (for example, every few milliseconds), a determination is repeatedly made as to whether or not the magnetic field distribution (filtered magnetic field distribution) detected by the detection unit 206 and spatially filtered by the spatial filter processing unit 208 matches each of the reference magnetic field distributions corresponding to the types of permanent magnets 7. Then, when the filtered magnetic field distribution matches the reference magnetic field distribution for one type of permanent magnet 7 a predetermined number of times or more in succession, it is determined that the permanent magnet 7 of that type has been detected. Whether or not the filtered magnetic field distribution matches the reference magnetic field distribution is determined based on the correlation coefficient for each detection axis calculated using equation (1). Furthermore, the reference magnetic field distribution for each type of permanent magnet 7 is defined as installed magnet data 310.

[0058] The memory unit 300 is realized by a storage device such as a hard disk, a ROM (Read Only Memory), or a RAM (Random Access Memory), and stores programs, data, etc. that the processing unit 200 uses to comprehensively control the on-board control device 30. The memory unit 300 is also used as a work area for the processing unit 200, and temporarily stores the results of calculations that the processing unit 200 executes according to various programs, and input data via the operation unit 102 and the communication unit 108. In this embodiment, the memory unit 300 stores a determination program 302, installed magnet data 310, spatial filter coefficient data 320, and detection data 330.

[0059] 15 is a diagram showing an example of the detection data 330. The detection data 330 is data related to the magnetic field distribution detected by the magnetic sensor unit 10 and is generated for each detection by the magnetic sensor unit 10. Each piece of detection data 330 stores, in association with a detection ID, the detection time, the calculated running position calculated by the running position calculation unit 202 at the detection time, X-axis detected magnetic field distribution data, Y-axis detected magnetic field distribution data, and Z-axis detected magnetic field distribution data, which are magnetic field distributions detected by the detection unit 206, X-axis filtered magnetic field distribution data, Y-axis filtered magnetic field distribution data, and Z-axis filtered magnetic field distribution data, which are magnetic field distributions after spatial filtering by the spatial filter processing unit 208, correlation coefficient data, and a determination result. The correlation coefficient data stores, in association with a type ID indicating the type of permanent magnet 7, the correlation coefficient for each detection axis between the spatially filtered magnetic field distribution and the reference magnetic field distribution corresponding to the type, calculated by the determination unit 210. The determination result 327 stores data (type ID) and the like indicating the type of the permanent magnet 7 corresponding to the reference magnetic field distribution determined by the determining unit 210 to match the filtered magnetic field distribution.

[0060] 16 is a diagram showing an example of the installed magnet data 310. The installed magnet data 310 is data related to the permanent magnets 7 installed on the track 5, and is prepared for each type of permanent magnet 7. Each installed magnet data 310 stores, in association with a type ID, installation position data for the permanent magnet 7 of that type, and reference magnetic field distribution data for each detection axis, namely, X-axis reference magnetic field distribution data, Y-axis reference magnetic field distribution data, and Z-axis reference magnetic field distribution data.

[0061] [Processing flow] 17 is a flowchart illustrating the flow of the determination process performed by the on-board control device 30. This process is realized by the processing unit 200 executing the determination program 302, and is started, for example, prior to departure from the starting station.

[0062] First, the running position calculation unit 202 starts calculating the running position (step S1). Then, the detection unit 206 determines whether a magnetic field has been detected by the magnetic sensor unit 10. Specifically, it is determined that a magnetic field has been detected when the magnitudes of a predetermined number or more of the detection values ​​of the respective detection axes of the magnetic sensor elements included in the magnetic sensor unit 10 are equal to or greater than a predetermined threshold.

[0063] If a magnetic field is detected (step S3: YES), the detection unit 206 detects a magnetic field distribution for each detection axis based on the detection values ​​of each magnetic sensor element 12 (step S5). Next, the spatial filter processing unit 208 performs spatial filtering on the magnetic field distribution (detected magnetic field distribution) detected for each detection axis by the detection unit 206 (step S7). Subsequently, the determination unit 210 calculates a correlation coefficient between the magnetic field distribution after spatial filtering (filtered magnetic field distribution) and each of the reference magnetic field distributions for each type of permanent magnet 7 (step S9).

[0064] Then, whether the filtered magnetic field distribution matches each reference magnetic field distribution is determined depending on whether the calculated correlation coefficient is equal to or greater than a predetermined threshold. If they match, it is then determined whether the filtered magnetic field distribution matches a reference magnetic field distribution of the same type of permanent magnet 7 a predetermined number of times or more in succession. If there is a reference magnetic field distribution that matches the filtered magnetic field distribution a predetermined number of times or more in succession (step S11: YES), it is determined that a permanent magnet 7 of the type corresponding to that reference magnetic field distribution has been detected (step S13).

[0065] Then, the running position correction unit 204 corrects the running position using the installation positions of the determined type of permanent magnets 7 (step S15). After that, it is determined whether this process should be ended because an ending condition such as arrival at the terminal station has been met. If not (step S17: NO), the process returns to step S3 and the same process is repeated. If it should be ended (step S17: YES), this process is ended.

[0066] [Action and effect] According to this embodiment, it is possible to improve the accuracy with which the on-board equipment 1 can detect the permanent magnets 7 installed on the track 5 without error. That is, the on-board equipment 1 compares the magnetic field distribution obtained by spatially filtering the magnetic field distribution based on the detection values ​​of each magnetic sensor element 12 with a predetermined reference magnetic field distribution to determine that the train has passed the installation position of the permanent magnet 7. The permanent magnet 7 has its surface on which different magnetic poles are arranged as its upper surface, and is arranged so that the different magnetic poles are located in a direction along the track 5. Therefore, the magnetic field distribution detected by each of the multiple magnetic sensor elements 12 moving in a direction along the track is a magnetic field distribution that exhibits abrupt changes in the magnetic field at locations corresponding to the spatially different magnetic poles.

[0067] By performing spatial filtering including at least a differential element on such a magnetic field distribution, it becomes possible to capture spatially steep magnetic field changes. For example, magnetic fields generated by magnetized objects located relatively far from the magnetic sensor unit 10 or currents flowing in the rails may be larger in magnitude than the permanent magnet 7, but are detected as a magnetic field distribution that changes slowly in space. Therefore, the on-board device 1 can distinguish the permanent magnet 7 from other magnetic field-generating objects, accurately detect the permanent magnet 7, and determine whether or not the vehicle has passed the installation position of the permanent magnet 7.

[0068] It should be noted that the embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can of course be modified as appropriate within the scope of the present invention. [Explanation of symbols]

[0069] 1...Onboard device 10...Magnetic sensor section 12...Magnetic sensor element 30...On-board control device 200...Processing section 202...Travel position calculation unit 204...Travel position correction unit 206...Detection unit 208...spatial filter processing unit 210...Judgment section 300...Storage section 302...Judgment Program 310...Installation magnet data 300...Spatial filter coefficient data 320…Detection data 3...Railway vehicles 5... Orbit 7(7a~7e)...Permanent magnet

Claims

1. An on-board device mounted on a vehicle running on a track on which magnets are installed at predetermined installation positions, a magnetic sensor unit having a plurality of magnetic sensor elements arranged in a predetermined positional relationship to detect a magnetic field generated by the magnet when the magnet passes through the installation position; a processing unit that determines whether or not the magnetic sensor unit has passed the installation position based on the detection value of the magnetic sensor unit; Equipped with the magnet is arranged such that the surface on which the different magnetic poles are arranged faces upward, and the different magnetic poles are positioned in a direction along the trajectory; The processing unit a detection unit that detects a magnetic field distribution based on the detection values ​​of the magnetic sensor elements; a spatial filter processing unit that performs spatial filtering including at least a differential element on the detected magnetic field distribution; a determination unit that determines whether the magnetic field distribution after spatial filtering has passed through the installation position by comparing a predetermined reference magnetic field distribution with the magnetic field distribution after spatial filtering; having On-vehicle device.

2. the spatial filtering unit performs the spatial filtering process including at least a second-order differential element. The on-board device according to claim 1.

3. The magnetic sensor unit has the magnetic sensors arranged in a plane along the front-rear and left-right directions of the vehicle. The on-board device according to claim 1.

4. The magnets include a plurality of types of magnets that differ in any one of size, installation orientation, and magnetic pole arrangement pattern, a type of the magnet to be installed on the track is determined for each installation position at which the magnet is installed, The reference magnetic field distribution includes a reference magnetic field distribution for each type of magnet, the determination unit compares the magnetic field distribution subjected to the spatial filtering process by the spatial filtering processing unit with reference magnetic field distributions for each type of magnet, and determines the type of magnet installed at the installation position through which the magnetic field distribution passes. The on-board device according to any one of claims 1 to 3.

5. the magnetic sensor element has a plurality of detection axes; the detection unit detects the magnetic field distribution for each of the detection axes, the reference magnetic field distribution includes a reference magnetic field distribution for each of the detection axes, the determination unit compares, for each of the detection axes, a reference magnetic field distribution of the detection axis with the magnetic field distribution of the detection axis that has been subjected to the spatial filtering process; The on-board device according to any one of claims 1 to 3.

6. A method for determining whether an on-board device mounted on a vehicle running on a track with a magnet installed at a predetermined installation position, the on-board device including a magnetic sensor unit having a plurality of magnetic sensor elements arranged in a predetermined positional relationship to detect a magnetic field generated by the magnet when the vehicle passes the installation position, based on a detection value of the magnetic sensor unit, comprising: the magnet is arranged such that the surface on which the different magnetic poles are arranged faces upward, and the different magnetic poles are positioned in a direction along the track; detecting a magnetic field distribution based on the detection values ​​of the magnetic sensor elements; performing a spatial filtering process including at least a differential element on the detected magnetic field distribution; determining whether the magnetic field distribution after spatial filtering has passed through the installation position by comparing a predetermined reference magnetic field distribution with the spatially filtered magnetic field distribution; A determination method including:

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