JP2020006845A - Track curvature estimation device and method - Google Patents

Abstract

To provide a track curvature estimation device and a method by which the curvature of a track can be easily obtained without measuring various parameters precisely.SOLUTION: The track curvature estimation device is installed on a vehicle 1 and includes an area sensor camera 11 imaging a curve on a track 2 in a traveling direction of the vehicle 1 and a processing unit 13 obtaining a curvature radius of the curve based on an image A acquired by the area sensor camera 11. The processing unit 13 includes a track position detection unit 21 obtaining an on-image track position D of the curve, a coefficient calculation unit 22 that is input with information about an actual track position d and its curvature radius R in plural points on the curve in advance to obtain a curvature radius estimation coefficient showing a correspondence relation between the on-image track position D, which corresponds to the actual track position d in the plural points, and its curvature radius R in the curve, and a curvature radius estimation unit 23 obtaining the curvature radius of the curve based on a position of the curve on the image and the correspondence relation.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an apparatus and a method for estimating a track curvature by image processing in the field of railways.

  Conventionally, for measuring the curvature of a curve using a camera on a railway track, a method in which parameters such as a vehicle center position and a camera position are accurately measured and derived from these parameters by calculation as in Patent Document 1 below. is there. The purpose of Patent Literature 1 below is to measure the presence or absence of obstacles within the building limit, but in Patent Literature 1 below, the curvature of the line required to calculate the building limit frame is obtained by image processing. And its method is described.

  Patent Literature 1 below has a camera installed on a vehicle running on a track and capable of capturing a moving image, and an image synchronization device that synchronizes an image captured by the camera with speed information of the vehicle. Photographing the track space ahead in the traveling direction by the camera while running the vehicle on which the camera is installed, and at different positions on the track, between those calculated using the speed information. A track space obstacle detection system that detects the presence or absence of an obstacle in the track space by comparing two images photographed at a position where the distance becomes a selected distance is disclosed.

JP 2016-000598 A JP 2016-009506 A

  The above-mentioned Patent Document 1 has a method of calculating and calculating a curvature of a target curve from parameters such as an image of a camera mounted in front of a vehicle, a center of rotation of the vehicle, and a height of the camera. Therefore, it is necessary to precisely measure the parameter.

  However, it is extremely difficult to precisely measure the above parameters structurally, and the measurement error of the above parameters has a large influence on the calculation of the curvature. Further, there is a problem that it is necessary to perform the calculation for each frame, which increases the processing cost.

  In view of the above technical problems, an object of the present invention is to provide a line curvature estimating apparatus and method capable of easily obtaining a line curvature without precisely measuring various parameters.

A line curvature estimating apparatus according to a first aspect of the present invention for solving the above-mentioned problems includes:
A camera installed on the vehicle and imaging a curve on a track in a traveling direction of the vehicle;
A processing unit for calculating a radius of curvature of the curve based on the image acquired by the camera,
The processing unit includes:
A track position detection unit that determines the position of the curve on the image;
Information on the actual positions and the radii of curvature at a plurality of points on the curve is input in advance, and among the curves, the correspondence between the positions on the image corresponding to the actual positions at the plurality of points and the radii of the curvatures is shown. A coefficient calculation unit to be obtained;
A curvature radius estimating unit that calculates a curvature radius of the curve based on the position of the curve on the image and the correspondence relationship.

A line curvature estimating apparatus according to a second aspect of the present invention for solving the above-mentioned problems includes:
In the line curvature estimating apparatus according to the first aspect,
The position of the curve on the image, and the actual position at the plurality of points are both positions in the sleeper direction,
The coefficient calculating unit calculates, in plane coordinates using the position in the sleeper direction in the image direction and the value of the curvature as coordinate axes, a position on the image corresponding to an actual position at the plurality of points in the curve, and a curvature thereof. A point indicating the curvature of the reciprocal of the radius is plotted, and the correspondence is obtained as a linear equation from the plurality of plotted points.

A line curvature estimating apparatus according to a third aspect of the present invention for solving the above-mentioned problems includes:
In the line curvature estimating apparatus according to the second aspect,
When the plural points are two points,
The coefficient calculation unit plots, on the plane coordinates, a point on the image corresponding to the actual position at the two points and a point indicating the curvature of the curve, and passes through the two plotted points. The linear formula is obtained.

A line curvature estimating apparatus according to a fourth aspect of the present invention for solving the above-mentioned problems includes:
In the line curvature estimating apparatus according to the second aspect,
When the plurality of points is three or more,
The coefficient calculation unit plots, on the plane coordinates, points on the image corresponding to actual positions at the three or more points and points indicating the curvatures of the curves, and plots three or more points. The linear equation of the approximate straight line of the point is obtained.

A line curvature estimating apparatus according to a fifth invention for solving the above-mentioned problems,
In the line curvature estimation device according to any one of the first to fourth aspects,
An actual position at the plurality of points input in advance to the coefficient calculating unit and a position on the image of the curve obtained by the track position detecting unit are both positions of a track center.

A line curvature estimating apparatus according to a sixth aspect of the present invention for solving the above-mentioned problems,
In the line curvature estimation device according to any one of the first to fourth aspects,
The actual positions at the plurality of points input in advance to the coefficient calculation unit and the position of the curve on the image obtained by the line position detection unit are the positions of one-sided lines.

A method for estimating a line curvature according to a seventh aspect of the present invention for solving the above-mentioned problems includes:
A first step of obtaining actual positions and radii of curvature at a plurality of points on a curve to be measured on the track;
A second step of imaging the curve on a track in a traveling direction of the vehicle by a camera installed on the vehicle;
A third step of determining the position of the curve on the image from the image acquired by the camera;
A fourth step of determining a correspondence between a position on the image corresponding to an actual position at the plurality of points and a radius of curvature of the curve,
A fifth step of calculating a radius of curvature of the curve based on the position of the curve on the image and the correspondence.

A line curvature estimating method according to an eighth aspect of the present invention for solving the above-mentioned problems includes:
In the line curvature estimation method according to the seventh aspect,
The position of the curve on the image, and the actual position at the plurality of points are both positions in the sleeper direction,
In the fourth step, a position on the image corresponding to an actual position at the plurality of points and the curvature on the image in plane coordinates using the position in the sleeper direction on the image in the sleeper direction and the value of the curvature as coordinate axes, respectively. A point indicating the curvature of the reciprocal of the radius is plotted, and the correspondence is obtained as a linear equation from the plurality of plotted points.

A line curvature estimating method according to a ninth aspect of the present invention for solving the above-mentioned problems includes:
In the line curvature estimation method according to the eighth aspect,
When the plural points are two points,
The fourth step plots, in the plane coordinates, a point on the image corresponding to the actual position at the two points and a point indicating the curvature of the curve, and passes through the plotted two points The linear formula is obtained.

A line curvature estimating method according to a tenth aspect of the present invention for solving the above-mentioned problems includes:
In the line curvature estimation method according to the eighth aspect,
When the plurality of points is three or more,
The fourth step plots, in the plane coordinates, points on the image corresponding to actual positions at the three or more points and points indicating the curvature of the curves, and plots three or more points. The linear equation of the approximate straight line of the point is obtained.

A line curvature estimating method according to an eleventh aspect of the present invention for solving the above problems,
In the line curvature estimation method according to any one of the seventh to tenth aspects,
An actual position at the plurality of points obtained in the first step and a position on the image of the curve obtained in the third step are both positions of a track center.

A line curvature estimating method according to a twelfth aspect of the present invention for solving the above-mentioned problems includes:
In the line curvature estimation method according to any one of the seventh to tenth aspects,
An actual position at the plurality of points acquired in the first step and a position on the image of the curve obtained in the third step are both positions of a one-side track.

  ADVANTAGE OF THE INVENTION According to the line curvature estimation apparatus and method concerning this invention, the curvature of a line can be calculated | required easily, without measuring various parameters precisely.

It is a schematic diagram showing the track curvature estimating device concerning the example of the present invention installed in the vehicle. 1 is a block diagram illustrating a line curvature estimation device according to an embodiment of the present invention. FIG. 4 is a schematic diagram illustrating an image acquired by an area sensor camera according to the embodiment of the present invention. FIG. 5 is a schematic diagram illustrating an example in which the position of a curve is detected from the image by the line position detection unit according to the embodiment of the present invention. 6 is an example of a graph of a radius of curvature estimation coefficient obtained by a coefficient calculation unit according to the embodiment of the present invention. 9 is another example of a graph of a curvature radius estimation coefficient obtained by the coefficient calculation unit in the embodiment of the present invention. FIG. 8 is a schematic diagram illustrating another example in which the position of a curve is detected from the image by the line position detection unit according to the embodiment of the present invention. 5 is a flowchart illustrating a procedure for obtaining a radius of curvature in the embodiment of the present invention.

  The track curvature estimating apparatus and method according to the present invention provide an image obtained from an area sensor camera mounted on the front side of a traveling vehicle, and a coefficient calculated based on a radius of curvature of a corresponding curve. By calculating (estimating) the radius of curvature, it is possible to derive a conversion coefficient as long as there are two or more radii of curvature, without the need for precise camera installation conditions as in the case of calculating the curvature by calculation. The radius of curvature can be determined.

  Hereinafter, an apparatus and a method for estimating a line curvature according to the present invention will be described in embodiments with reference to the drawings.

  First, the configuration of the line curvature estimation device according to the present embodiment will be described. FIG. 1 is a schematic diagram illustrating a track curvature estimating device according to the present embodiment, which is installed in a vehicle 1. FIG. 2 is a block diagram illustrating the line curvature estimating apparatus according to the present embodiment.

  As shown in FIG. 1, the track curvature estimating apparatus according to the present embodiment installed in the vehicle 1 mainly includes an area sensor camera 11, a storage unit 12, and a processing unit 13.

  The area sensor camera 11 is arranged in front of the roof 1 a of the vehicle 1 traveling on the track 2, and captures an image of the track 2 in the traveling direction of the vehicle 1. The image acquired by the area sensor camera 11 is stored in the storage unit 12.

  The processing unit 13 obtains (estimates) the radius of curvature of the curve to be measured on the track 2 based on the image acquired by the area sensor camera 11 and stored in the storage unit 12. As shown in FIG. 2, the processing unit 13 includes a line position detecting unit 21, a coefficient calculating unit 22, and a curvature radius estimating unit 23.

  The track position detection unit 21 detects a curve to be measured from the image acquired by the area sensor camera 11 (for the detection method, see, for example, Patent Document 2), and obtains the position of the curve on the image.

  This processing will be specifically described with reference to FIGS. 3A and 3B. FIG. 3A is a schematic diagram illustrating an image A acquired by the area sensor camera 11, and FIG. 3B is a schematic diagram illustrating a state in which the position of a curve is detected from the image A by the line position detection unit 21.

  The track position detecting unit 21 detects a track B (on the image A) from the image A acquired by the area sensor camera 11 as shown in FIG. 3A (see FIG. 3B). The small circle C indicates a state in which the line B is detected by the line position detection unit 21).

  Further, as indicated by a broken line in FIG. 3B, in the image A, the orbit center D of the line B intersecting with the virtual line extending in the sleeper direction is represented as an x coordinate [pix]. This represents the position on the image of the curve to be measured. Hereinafter, the position D on the image will be referred to as “image line position D”.

  The coefficient calculation unit 22 stores information on the actual positions d and the radii of curvature R at a plurality of points on the curve to be measured, which have been obtained in advance, separately from the line position D on the image obtained by the line position detection unit 21 in advance. Has been entered. Here, “acquired in advance” means that the area sensor camera 11 was acquired by actual measurement instead of using it. The actual positions d at the plurality of points indicate the positions of the railroad tracks 2 in the crossties direction and the positions of the track centers of the railroad tracks 2 and are hereinafter referred to as “real railroad track positions d”.

  Then, the coefficient calculation unit 22 obtains a correspondence relationship between the line position D on the image corresponding to the actual line position d at the plurality of points and the curvature radius R as a “curvature radius estimation coefficient”.

FIG. 4 is an example of a graph in which the calculation performed by the coefficient calculation unit 22 is performed.
First, as shown in FIG. 4, plane coordinates are prepared in which the horizontal axis represents the above-mentioned coordinates x and the vertical axis represents curvature (reciprocal 1 / R of the radius of curvature).

  Then, among the curves to be measured, points (plurality) indicating the line position D on the image corresponding to the actual line position d at the plurality of points and the curvature thereof (reciprocal 1 / R of the radius of curvature) are plotted.

  The plotted points are roughly linearly distributed. Therefore, an approximate straight line (y = ax + b) is obtained using these values. This is a coefficient for estimating the radius of curvature of the curve to be measured, that is, a radius of curvature estimation coefficient. However, these descriptions are based on the assumption that the plurality of points are three or more.

  When the plurality of points are only two points, as shown in FIG. 5, in the plane coordinates, the line position D on the image corresponding to the actual line position d at the two points and the curvature ( 1 / R) may be plotted, and a linear equation of a straight line passing through the two plotted points may be obtained. (As described above, if more points are plotted, the points are distributed linearly. Is known, it is no problem to assume that a line passing through two points is a "straight line"). However, when the approximate straight line is obtained using three or more points, the estimation error can be reduced.

  The radius of curvature estimating unit 23 calculates the line position D on the image of the entire curve to be measured in the image A (determined by the line position detecting unit 21) and the radius of curvature estimation coefficient (determined by the coefficient calculating unit 22). Based on this, the curvature of the curve to be measured in the image A (that is, the line for each frame) is determined (estimated), and the reciprocal thereof is calculated to determine the radius of curvature.

  Note that the line position detection unit 21 changes the output destination of the detection result depending on whether or not the curvature radius estimation coefficient has already been obtained. That is, if the curvature radius estimation coefficient has not been obtained yet, the image line position D is transmitted to the coefficient calculation unit 22. If the radius of curvature estimation coefficient has already been obtained, the line position D on the image is transmitted to the radius of curvature estimation unit 23.

  That is, in the line curvature estimating apparatus according to the present embodiment, the curvature radius estimation coefficient need only be derived once, and thereafter, the curvature radius can be obtained based on the obtained curvature radius estimation coefficient.

  Further, in the present embodiment, the track center of the track B on the image A is the track position D on the image, and the track center actual track position d of the actual track 2 is described. However, the present invention is not limited to this. For example, as shown in FIG. 6, the position of one side of the line B on the image A may be set as the line position D on the image, and the position of the actual one side of the line 2 may be set as the actual line position d.

  This is because the track width is the same for each business operator, so that the calculation described in the present embodiment is satisfied without obtaining the track center. By setting the position of the one-side line as the line position D on the image, the processing cost can be reduced.

  Next, a procedure for obtaining the radius of curvature using the line curvature estimating apparatus according to the present embodiment will be described with reference to the flowchart of FIG.

  In step S1, the actual track position d and the curvature radius R of a plurality of points on the curve to be measured are obtained in advance by actual measurement.

  In step S <b> 2, the area sensor camera 11 installed in the vehicle 1 captures an image of a curve to be measured on the track 2 in the traveling direction of the vehicle 1, and stores the captured image in the storage unit 12.

  In step S <b> 3, the line position detection unit 21 of the processing unit 13 obtains the line position D on the image of the curve to be measured from the image A.

  In step S4, the coefficient calculation unit 22 of the processing unit 13 obtains a curvature radius estimation coefficient based on the image-based line position D and the curvature radius R corresponding to the actual line position d at the plurality of points. The curvature radius estimation coefficient is stored in the coefficient calculation unit or the curvature radius estimation unit.

  In step S5, the radius of curvature R of the curve to be measured including points other than the plurality of points is determined by the radius of curvature estimating unit 23 of the processing unit 13 based on the radius of curvature estimation coefficient and the line position D on the image of the curve to be measured. Ask for.

  In the prior art, parameters such as the center of the installed vehicle and the height of the camera had to be precisely measured, and furthermore, calculation processing had to be performed for each frame. The curvature estimating device simply obtains a coefficient for deriving a radius of curvature at each coordinate by inputting two or more track positions and their radii of curvature at the time of installation, and thereafter simply calculates the radius of curvature from the line position coordinates. Can be calculated, and it is not necessary to perform detailed parameter measurement at the time of installation, and the processing cost can be reduced.

  INDUSTRIAL APPLICABILITY The present invention is suitable as a railway curvature estimating apparatus and method by image processing in the railway field.

Reference Signs List 1 vehicle 1a on roof (of vehicle 1) 2 track 11 area sensor camera 12 storage unit 13 processing unit 21 track position detecting unit 22 coefficient calculating unit 23 curvature radius estimating unit A image B (obtained by area sensor camera 11) Track C (on A) Small circle D (on image A) Track position (on image A) Track center (track center)

Claims (12)

A camera installed on the vehicle and imaging a curve on a track in a traveling direction of the vehicle;
A processing unit for calculating a radius of curvature of the curve based on the image acquired by the camera,
The processing unit includes:
A track position detection unit that determines the position of the curve on the image;
Information on the actual positions and the radii of curvature at a plurality of points on the curve is input in advance, and among the curves, the correspondence between the positions on the image corresponding to the actual positions at the plurality of points and the radii of the curvatures is shown. A coefficient calculation unit to be obtained;
A curvature radius estimating unit that obtains a curvature radius of the curve based on the position of the curve on the image and the correspondence relationship. The position of the curve on the image, and the actual position at the plurality of points are both positions in the sleeper direction,
The coefficient calculating unit calculates, in plane coordinates using the position in the sleeper direction in the image direction and the value of the curvature as coordinate axes, a position on the image corresponding to an actual position at the plurality of points in the curve, and a curvature thereof. The line curvature estimating device according to claim 1, wherein a point indicating a curvature of a reciprocal of a radius is plotted, and the correspondence is obtained as a linear expression from the plurality of plotted points. When the plural points are two points,
The coefficient calculation unit plots, on the plane coordinates, a point on the image corresponding to the actual position at the two points and a point indicating the curvature of the curve, and passes through the two plotted points. The line curvature estimating apparatus according to claim 2, wherein the straight line equation is obtained. When the plurality of points is three or more,
The coefficient calculation unit plots, on the plane coordinates, points on the image corresponding to actual positions at the three or more points and points indicating the curvatures of the curves, and plots three or more points. The line curvature estimating device according to claim 2, wherein the straight line equation of the approximate straight line of the point is obtained. The actual positions at the plurality of points input in advance to the coefficient calculation unit and the position on the image of the curve determined by the track position detection unit are both the positions of track centers. The line curvature estimating device according to any one of items 1 to 4. The actual positions at the plurality of points input in advance to the coefficient calculating unit and the position of the curve on the image obtained by the line position detecting unit are both single-sided line positions. The line curvature estimating device according to any one of items 1 to 4. A first step of obtaining actual positions and radii of curvature at a plurality of points on a curve to be measured on the track;
A second step of imaging the curve on a track in a traveling direction of the vehicle by a camera installed on the vehicle;
A third step of determining the position of the curve on the image from the image acquired by the camera;
A fourth step of determining a correspondence between a position on the image corresponding to an actual position at the plurality of points and a radius of curvature of the curve,
A fifth step of obtaining a radius of curvature of the curve based on the position of the curve on the image and the correspondence relationship. The position of the curve on the image, and the actual position at the plurality of points are both positions in the sleeper direction,
In the fourth step, a position on the image corresponding to an actual position at the plurality of points and the curvature on the image in plane coordinates using the position in the sleeper direction on the image in the sleeper direction and the value of the curvature as coordinate axes, respectively. The line curvature estimating method according to claim 7, wherein a point indicating a curvature of a reciprocal of a radius is plotted, and the correspondence is obtained as a linear equation from the plurality of plotted points. When the plural points are two points,
The fourth step plots, in the plane coordinates, a point on the image corresponding to the actual position at the two points and a point indicating the curvature of the curve, and passes through the plotted two points The line curvature estimating method according to claim 8, wherein the straight line equation is obtained. When the plurality of points is three or more,
The fourth step plots, in the plane coordinates, points on the image corresponding to actual positions at the three or more points and points indicating the curvature of the curves, and plots three or more points. The line curvature estimating method according to claim 8, wherein the straight line equation of the approximate straight line of the point is obtained. The actual positions at the plurality of points obtained in the first step and the position on the image of the curve obtained in the third step are both the positions of the trajectory centers. The line curvature estimation method according to any one of the above. The actual positions at the plurality of points obtained in the first step and the position on the image of the curve obtained in the third step are both positions of a one-sided track. The line curvature estimation method according to any one of the above.

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