Soundness determination system

Abstract

To determine the soundness of satellite positioning on a ground side.SOLUTION: A soundness determination system 1 includes: three receivers 4A, 4B, and 4C for performing satellite positioning; and a processing unit 5 for processing the result of positioning by the receivers 4A, 4B, and 4C. The receivers 4A, 4B, and 4C are set in positionally known points on the ground. Each known point forms an apex of a reference triangle ABC. A processing unit 5 determines the soundness of the satellite positioning on the basis of the comparison in the position and in the shape between a sequential triangle PQR of which apexes are the results of positioning by the three receivers 4A, 4B, and 4C and a reference triangle ABC.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a soundness determination system for determining the soundness of satellite positioning. [Background technology]

[0002] Traditionally, train position detection has generally been performed using track circuits. The maintenance, management, and updating of track circuits, which are ground equipment, is a heavy burden for railway operators, especially regional railway operators. Because track circuit maintenance and management requires direct on-site visits, it is becoming more difficult to secure personnel to perform maintenance and management as the aging of society progresses. In addition, because track circuits are large equipment, the time and cost required for updating them is enormous.

[0003] Under these circumstances, there is a growing expectation for detecting train positions without using track circuits. One of the means for detecting positions is satellite positioning. Systems that perform satellite positioning (satellite positioning systems) include GPS and quasi-zenith satellites. It has been proposed to use GPS for detecting train positions (for example, see Patent Document 1).

[0004] Satellite positioning detects the current position by receiving radio waves transmitted from multiple satellites via an antenna at a receiver. For this reason, positioning is not possible in places where it is difficult to receive radio waves, such as inside tunnels. Also, in places where high-rise buildings are densely packed, the positioning accuracy decreases due to receiving radio waves reflected by buildings (multipath). On lines that include such places, it is difficult to detect the position of a train using satellite positioning alone, and it is necessary to combine it with a speed generator or other sensors (such as a gyro sensor), but on other lines, it is possible to detect the position of a train using satellite positioning alone.

[0005] Since train position detection is used for security purposes such as train control and crossing control to ensure train safety, if train position detection is performed solely by satellite positioning, it is necessary to determine whether the train position detected by satellite positioning is valid. If the validity of satellite positioning is determined by on-board equipment, the on-board equipment must be installed on all trains on the target line, which is costly. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2008-253035 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention is devised to solve the above problem, and has an object to provide a soundness determination system for determining the soundness of satellite positioning on the ground. [Means for solving the problem]

[0008] The soundness assessment system of the present invention is a system for assessing the soundness of satellite positioning, and is equipped with three receivers that perform satellite positioning and a processing unit that processes the positioning results by the receivers, each of the receivers being installed at a known point on the ground whose position is known, and each of the known points forming a vertex of a reference triangle, and the processing unit assesses the soundness of the satellite positioning based on a comparison of the position and shape of a successive triangle having the positioning results of the three receivers as vertices with the reference triangle.

[0009] In this soundness determination system, it is preferable that the processing unit determines that the satellite positioning is sound when the change in position and shape of the successive triangle from the reference triangle is within a predetermined determination criterion.

[0010] In this health determination system, it is preferable that the processing unit determines that the satellite positioning is healthy when each of the three vertices of the sequential triangle is within a predetermined distance from a corresponding vertex in the reference triangle.

[0011] In this soundness judgment system, when the change in shape of the successive triangle from the reference triangle is within a predetermined judgment criterion and the change in position exceeds a predetermined judgment criterion, it is preferable that the processing unit outputs a judgment result that the satellite positioning is not sound.

[0012] In the soundness assessment system of the present invention, when the lengths of the three sides of the sequential triangle do not change from the lengths of the corresponding sides in the reference triangle by more than a predetermined allowable error, and at least one of the three vertices of the sequential triangle is not within a predetermined distance from the corresponding vertex in the reference triangle, it is preferable that the processing unit outputs a assessment result that the satellite positioning is not sound.

[0013] In this soundness judgment system, when the change in shape of the successive triangle from the reference triangle exceeds a predetermined judgment criterion, it is preferable that the processing unit outputs a judgment result that the soundness of the satellite positioning cannot be confirmed.

[0014] In the soundness judgment system of the present invention, when the length of at least one of the three sides of the sequential triangle changes from the length of the corresponding side in the reference triangle by more than a predetermined allowable error, the processing unit preferably outputs a judgment result that the soundness of the satellite positioning cannot be confirmed.

[0015] In this health assessment system, it is preferable that the system has a ground transmission unit provided on the ground side and an on-board receiving unit provided in the vehicle, and that the processing unit transmits the assessment result to the ground transmission unit, and the on-board receiving unit reports the received assessment result.

[0016] This health assessment system may further include a fourth receiver at a known position spaced apart from the apex of the reference triangle, and the receiver installed at the apex of the reference triangle may perform real-time kinematic positioning using the fourth receiver as a reference station. Effect of the Invention

[0017] According to the soundness assessment system of the present invention, satellite positioning is performed using receivers installed at the three vertices of a reference triangle on the ground, and the soundness of the satellite positioning is assessed based on a comparison of the positions and shapes of successive triangles with the positioning results as their vertices with the reference triangle, thereby making it possible to assess the soundness of the satellite positioning on the ground. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a block diagram of a health determination system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view illustrating a sequential triangle in the system when the satellite positioning is sound. [Diagram 3] FIG. 3 is a plan view illustrating the sequential triangles in the system when the satellite positioning is not robust. [Figure 4] FIG. 4 is a plan view illustrating a sequential triangle in the system when the soundness of the satellite positioning cannot be confirmed. [Diagram 5] FIG. 5 is a block diagram of a healthiness determination system according to a modified example of the embodiment. [Figure 6] FIG. 6 is a plan view showing the arrangement of receivers in this modified example. [Figure 7] FIG. 7 is a flowchart of the judgment in the soundness judgment system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] A soundness determination system according to one embodiment of the present invention will be described with reference to Fig. 1 to Fig. 4 and Fig. 7. As shown in Fig. 1, in this embodiment, a vehicle 2 is operated as a train on a route subject to satellite positioning, and performs satellite positioning. That is, the vehicle 2 receives radio waves transmitted from a satellite 3 with an on-board receiver 21 to detect its own current position. The soundness determination system 1 is a system that determines the soundness of satellite positioning.

[0020] The soundness determination system 1 includes three receivers 4A, 4B, and 4C, and a processing unit 5. The receivers 4A, 4B, and 4C are collectively referred to as receivers 4. Each receiver 4 performs satellite positioning. The processing unit 5 processes the positioning results by the receiver 4. The receiver 4 is, for example, a GPS receiver, and may be a receiver compatible with the Quasi-Zenith Satellite System. The processing unit 5 is, for example, a computer, has a CPU, memory, etc., and functions by executing a program.

[0021] As shown in Figure 2, receivers 4A, 4B, and 4C are installed at known points A, B, and C on the ground, whose positions are known. The known points A, B, and C form the vertices of a triangle ABC. This triangle ABC is called the reference triangle. That is, receiver 4A is installed at vertex A of the reference triangle ABC, receiver 4B is installed at vertex B, and receiver 4C is installed at vertex C.

[0022] The receivers 4A, 4B, and 4C perform satellite positioning and sequentially output the positioning results. In this embodiment, the receivers 4A, 4B, and 4C perform positioning at all times, so the sequential time intervals for performing satellite positioning are short. The specific time intervals for performing satellite positioning are not limited. The positioning results of the three receivers 4A, 4B, and 4C form the vertices of a triangle PQR. The triangle PQR is called a sequential triangle. That is, the vertex P of the sequential triangle PQR indicates the measurement result of the known point A by the receiver 4A. The vertex Q indicates the measurement result of the known point B by the receiver 4B. The vertex R indicates the measurement result of the known point C by the receiver 4C. The vertices P, Q, and R of the sequential triangle PQR correspond to the vertices A, B, and C of the reference triangle ABC, respectively.

[0023] If the satellite positioning by the receiver 4 is completely accurate, the sequential triangle PQR and the reference triangle ABC are mathematically identical in position and shape. In reality, the positioning results of the satellite positioning contain a certain degree of error, so when the satellite positioning is sound, the sequential triangle PQR and the reference triangle ABC are substantially identical in position and shape within the range of the allowable error. When at least one of the position and shape of the sequential triangle PQR has substantially changed from the reference triangle ABC, the satellite positioning cannot be said to be sound. The soundness determination system 1 uses this to determine the soundness of the satellite positioning.

[0024] The processor 5 judges the soundness of the satellite positioning based on a comparison of the position and shape of a successive triangle PQR having the positioning results of the three receivers 4A, 4B, and 4C as vertices with a reference triangle ABC.

[0025] There are three possible results of the judgment by the processing unit 5: the satellite positioning is sound, the satellite positioning is not sound, and the soundness of the satellite positioning cannot be confirmed. If both the side being judged (satellite 3, etc.) and the side making the judgment (soundness judgment system 1) are normal, the satellite positioning is sound. If there is an abnormality on the side being judged (satellite 3, etc.), the satellite positioning is not sound. If there is an abnormality on the side making the judgment (soundness judgment system 1), the soundness of the satellite positioning cannot be confirmed.

[0026] The judgment in the processing unit 5 involves comparing the position and shape of a triangle, which is a planar figure, and therefore includes a judgment method based on calculations based on analytical geometry and a judgment method based on image processing of a drawn triangle, as described below.

[0027] First, a case where the satellite positioning is sound will be described. When the change in the position and shape of the successive triangle PQR from the reference triangle ABC is within a predetermined judgment criterion, the processing unit 5 judges that the satellite positioning is sound (see FIG. 2).

[0028] The criteria can be quantitatively expressed using analytical geometry. Analytical geometry is also called coordinate geometry, and is geometry that handles figures algebraically using coordinates. The reference triangle ABC is expressed by the coordinates of vertices A, B, and C. The sequential triangle PQR is expressed by the coordinates of vertices P, Q, and R. The position and shape of a triangle are determined once the coordinates of the three vertices are determined. In this embodiment, the comparison of the position and shape of a triangle is performed by calculation based on the coordinates.

[0029] When each of the three vertices P, Q, R of the successive triangle PQR is within a predetermined distance ε from the corresponding vertices A, B, C in the reference triangle ABC, the processing unit 5 determines that the satellite positioning is sound.

[0030] In FIG. 2, the predetermined distance ε from the vertices A, B, and C of the reference triangle ABC is a circle of radius ε, and is called the tolerance circle. The vertex P of the successive triangle PQR being inside the tolerance circle EA centered on the vertex A of the reference triangle ABC is the same as the vertex P of the successive triangle PQR being within the predetermined distance ε from the vertex A of the reference triangle ABC. Similarly, the vertex Q of the successive triangle PQR being inside the tolerance circle EB centered on the vertex B of the reference triangle ABC is the same as the vertex Q of the successive triangle PQR being within the predetermined distance ε from the vertex B of the reference triangle ABC. Also, the vertex R of the successive triangle PQR being inside the tolerance circle EC centered on the vertex C of the reference triangle ABC is the same as the vertex R of the successive triangle PQR being within the predetermined distance ε from the vertex C of the reference triangle ABC. When the position and shape of the successive triangle PQR from the reference triangle ABC have not substantially changed in consideration of the tolerance, the processing unit 5 will determine that the satellite positioning is sound. The smaller the radius ε of the tolerance circles EA, EB, and EC, the stricter the judgment.

[0031] Next, we will explain the case where the satellite positioning is not sound. If the satellite 3 fails or the line is subjected to jamming waves (see Figure 1), there is a high possibility that the positioning results of the three receivers 4A, 4B, and 4C will be uniformly affected, and as shown in Figure 3, the successive triangle PQR will translate from the reference triangle ABC beyond the allowable error circles EA, EB, and EC. At this time, the satellite positioning is in a state where its soundness is impaired. In geometry, when a triangle translates, the shape of the triangle does not change, but the position changes.

[0032] When the change in shape of the successive triangle PQR from the reference triangle ABC is within a predetermined criterion and the change in position exceeds a predetermined criterion, the processing unit 5 outputs a determination result that the satellite positioning is not sound.

[0033] In geometry, when the shape of a triangle does not change, the lengths of the sides of the triangle do not change. Also, when the position of a triangle changes, at least one of the three vertices of the triangle moves.

[0034] When the lengths of the three sides of the successive triangle PQR do not vary from the lengths of the corresponding sides in the reference triangle ABC by more than a predetermined allowable error, and at least one of the three vertices P, Q, R of the successive triangle PQR is not within a predetermined distance ε from the corresponding vertices A, B, C in the reference triangle ABC, the processing unit 5 outputs a determination result that the satellite positioning is not sound. In this embodiment, the predetermined allowable error of the side lengths is the same as the radius ε of the allowable error circles EA, EB, EC.

[0035] In this embodiment, the reference triangle ABC is a right-angled triangle. A right-angled triangle satisfies Pythagoras' theorem. For example, the reference triangle ABC illustrated in FIG. 2 is a right-angled triangle with the ratio of the lengths of the three sides being 3:4:5. The processing unit 5 may use Pythagoras' theorem to detect a change in the shape of the successive triangle PQR from the reference triangle ABC. The reference triangle ABC may also be an equilateral triangle. An equilateral triangle has three sides that are equal in length.

[0036] In the soundness determination system 1, the processing unit 5 may detect the presence or absence of a change in the shape of the successive triangle PQR from the reference triangle ABC by image processing. By making the reference triangle ABC a right-angled triangle or an equilateral triangle, it becomes easy to detect the change in the shape of the successive triangle PQR by image processing.

[0037] The following describes how to notify the vehicle 2 when the satellite positioning is determined to be unsound (see FIG. 1). The soundness determination system 1 has a ground transmitter 6 and an on-board receiver 7. The ground transmitter 6 is provided on the ground. The on-board receiver 7 is provided in the vehicle 2. The processing unit 5 causes the ground transmitter 6 to transmit the determination result. The on-board receiver 7 notifies the received determination result.

[0038] The on-board receiving unit 7 is, for example, an on-board station of an existing train radio system. The on-board receiving unit 7 may be an on-board radio dedicated to the health determination system 1. When the on-board receiving unit 7 receives the determination result, it notifies the train crew of the determination result by voice or the like. If the satellite positioning is not sound, the train crew who is notified of the determination result stops the train.

[0039] Next, a case where the soundness of satellite positioning cannot be confirmed will be described. For example, if the receiver 4A of the soundness judgment system 1 fails (see FIG. 1), as shown in FIG. 4, the vertex P of the triangle PQR moves beyond the allowable error circle EA centered on the vertex A of the reference triangle ABC, and the shape of the triangle PQR changes sequentially. If the receiver 4B fails, and if the receiver 4C fails, the shape of the triangle PQR also changes sequentially. If two receivers 4 fail simultaneously, the shape of the triangle PQR also changes sequentially. If the shape of the triangle PQR changes sequentially, this indicates that the soundness of the judging side has been compromised.

[0040] When the change in the shape of the successive triangle PQR from the reference triangle ABC exceeds a predetermined judgment criterion, the processing unit 5 outputs a judgment result that the soundness of the satellite positioning cannot be confirmed.

[0041] In geometry, when the shape of a triangle changes, the lengths of the sides change.

[0042] When the length of at least one of the three sides of the successive triangle PQR changes from the length of the corresponding side in the reference triangle ABC by more than a predetermined allowable error, the processing unit 5 outputs a determination result that the soundness of the satellite positioning cannot be confirmed.

[0043] If the determination result indicates that the soundness of the satellite positioning cannot be confirmed, the processing unit 5 transmits the determination result to the ground transmitting unit 6. The on-board receiving unit 7 notifies the received determination result (see FIG. 1). The crew, who receives the notification of the determination result, stops the train.

[0044] It is desirable for the on-board receiving unit 7 to report that the soundness of the satellite positioning cannot be confirmed even when communication with the ground transmitting unit 6 is interrupted. Specifically, for example, even when the processing unit 5 determines that the satellite positioning is sound, it causes the processing unit 5 to transmit the result of the determination to the ground transmitting unit 6 at a predetermined period. When the on-board receiving unit 7 does not receive communication from the ground transmitting unit 6 for a period exceeding that period, it reports that the soundness of the satellite positioning cannot be confirmed. The crew member who receives the report stops the train.

[0045] 7 is a flowchart summarizing the flow of judgment in the above-mentioned soundness judgment system 1. The processing unit 5 sequentially compares the position and shape of the triangle PQR with the reference triangle ABC (step S101). That is, the processing unit 5 sequentially evaluates the change in the position and shape of the triangle PQR from the reference triangle ABC.

[0046] When the change in shape of the successive triangle PQR from the reference triangle ABC exceeds a predetermined criterion (No in step S102), the processing unit 5 determines that the soundness of the satellite positioning cannot be confirmed, and outputs the determination result (step S103).

[0047] When the change in shape of the successive triangle PQR from the reference triangle ABC is within a predetermined judgment criterion (Yes in step S102) and the change in position exceeds a predetermined judgment criterion (No in step S104), the processing unit 5 judges that the satellite positioning is not sound and outputs the judgment result (step S105).

[0048] When the change in the position and shape of the successive triangle PQR from the reference triangle ABC falls within a predetermined criterion (Yes in step S104), the processing unit 5 determines that the satellite positioning is sound (step S106).

[0049] In the method of judgment by calculation based on analytical geometry, the criterion for judging a change in position is set as the distance of a vertex of successive triangle PQR from the corresponding vertex of reference triangle ABC, and the criterion for judging a change in shape is set as the change in the length of a side of successive triangle PQR from the length of a corresponding side of reference triangle ABC.

[0050] In the soundness determination system 1, the processing unit 5 may have a trained classifier. The classifier has a neural network, and machine learning is performed in advance to classify the image of the successive triangle PQR into three classes, that is, the satellite positioning is sound, the satellite positioning is not sound, and the soundness of the satellite positioning cannot be confirmed, by supervised learning. The determination criteria based on the change in the position and shape of the successive triangle PQR from the reference triangle ABC are set as parameters of the neural network.

[0051] As described above, according to the soundness determination system 1 of this embodiment, satellite positioning is performed by receivers 4A, 4B, and 4C installed at three vertices A, B, and C of a reference triangle ABC on the ground, and the soundness of the satellite positioning is determined based on a comparison of the position and shape of a sequential triangle PQR having the positioning results as vertices with the reference triangle ABC, so that the soundness of the satellite positioning can be determined on the ground side. Also, when it is not determined that the satellite positioning is sound, it is possible to distinguish between a case where the satellite positioning is not sound and a case where the soundness of the satellite positioning cannot be confirmed.

[0052] A soundness determination system 1 according to a modified example of this embodiment will be described with reference to Figs. 5 and 6. As shown in Fig. 5, the soundness determination system 1 further includes a fourth receiver 4D. As shown in Fig. 6, the fourth receiver 4D is installed at a known position D spaced apart from the vertices of the reference triangle ABC. The receivers 4A, 4B, and 4C installed at the vertices of the reference triangle ABC perform real-time kinematic positioning with the fourth receiver 4D as a reference station. In the example of Fig. 6, the reference triangle ABC is a right-angled triangle, and the figure ABCD is a rectangle.

[0053] Real-Time Kinematic (RTK) positioning is a positioning method that simultaneously performs satellite positioning at a reference station whose position is known and at a point whose position is unknown (unknown point), transmits observation information at the reference station (radio wave information from the satellite, satellite information captured at the reference point, etc.) by wireless or other means to the unknown point, and determines the position of the unknown point in a short period of time by combining it with the observation information at the unknown point. In this modified example, receivers 4A, 4B, and 4C are receivers for the unknown points, and the fourth receiver is the reference station.

[0054] The real-time kinematic positioning improves the accuracy of positioning by the receivers 4A, 4B, and 4C. Therefore, the radius ε of the permissible error circles EA, EB, and EC can be made small, and the judgment accuracy of the soundness judgment system 1 is improved.

[0055] The present invention is not limited to the configuration of the above embodiment, and various modifications are possible without departing from the spirit of the invention. For example, the soundness determination system 1 may further include a display, and the triangle PQR and the reference triangle ABC may be displayed on the display in sequence, so that the soundness of the satellite positioning can be visually confirmed at all times. [Explanation of symbols]

[0056] 1. Soundness assessment system 4, 4A, 4B, 4C receiver 4D Fourth Receiver 5 Processing section 6 Ground Transmitter 7 On-board receiver

Claims

1. A soundness determination system for determining the soundness of satellite positioning, comprising: Three receivers for satellite positioning; a processing unit for processing a positioning result by the receiver, Each of the receivers is installed at a known point on the ground having a known position; Each of the known points forms a vertex of a reference triangle; The soundness determination system is characterized in that the processing unit determines the soundness of the satellite positioning based on a comparison of the position and shape of a sequential triangle having the positioning results of the three receivers as vertices with the reference triangle.

2. The health determination system according to claim 1 , wherein the processing unit determines that the satellite positioning is healthy when the change in position and shape of the successive triangle from the reference triangle is within a predetermined determination criterion.

3. 3. The health determination system according to claim 2, wherein the processing unit determines that the satellite positioning is healthy when each of the three vertices of the successive triangle is within a predetermined distance from a corresponding vertex in the reference triangle.

4. The soundness determination system of claim 1, characterized in that when the change in shape of the successive triangle from the reference triangle is within a predetermined judgment criterion and the change in position exceeds a predetermined judgment criterion, the processing unit outputs a judgment result that the satellite positioning is not sound.

5. The soundness determination system of claim 4, characterized in that when the lengths of the three sides of the successive triangle do not change from the lengths of the corresponding sides in the reference triangle by more than a predetermined allowable error, and at least one of the three vertices of the successive triangle is not within a predetermined distance from the corresponding vertex in the reference triangle, the processing unit outputs a determination result that the satellite positioning is not sound.

6. The soundness determination system described in claim 1, characterized in that when the change in shape of the successive triangle from the reference triangle exceeds a predetermined judgment criterion, the processing unit outputs a judgment result that the soundness of the satellite positioning cannot be confirmed.

7. The soundness determination system described in claim 6, characterized in that when the length of at least one of the three sides of the sequential triangle changes from the length of the corresponding side in the reference triangle by more than a predetermined allowable error, the processing unit outputs a determination result that the soundness of the satellite positioning cannot be confirmed.

8. A ground transmitting unit provided on the ground side; an on-board receiving unit provided in the vehicle; The processing unit transmits the determination result to the ground transmitting unit, 8. The vehicle health determination system according to claim 4, wherein the on-board receiver notifies the received determination result.

9. a fourth receiver at a known location spaced from an apex of the reference triangle; 2. The system for determining soundness according to claim 1, wherein the receivers installed at the vertices of the reference triangle perform real-time kinematic positioning using the fourth receiver as a reference station.

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