Distance measurement system and vehicle mounted therewith

Abstract

To provide technology that detects accuracy of a distance measurement system precisely without previously obtaining a binocular image serving as a basis for correction.SOLUTION: One representative distance measurement system of the present invention comprises a rail irregularity information generation unit that detects a rail and irregularities around the rail, a first rail position detection unit that outputs a rail position on the basis of the output of the rail irregularity information generation unit, a rail width calculation unit that outputs rail width information on the basis of the output of the first rail position detection unit, a first rail distance calculation unit that outputs a first rail distance on the basis of the rail width information, a second rail distance calculation unit that outputs a second rail distance on the basis of the output of a distance measurement unit, a distance error calculation unit that compares the first rail distance and the second rail distance and outputs an error, and a correction amount calculation unit that outputs a correction amount for the output of the distance measurement unit on the basis of the output of the distance error calculation unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a distance measurement system and a vehicle equipped with the same. [Background technology]

[0002] For a moving object, it is necessary to accurately confirm its own position and reliably detect obstacles from the viewpoint of ensuring safety. For this reason, technology that can accurately measure the distance in the moving direction of a moving object is important. Stereo cameras have been used as one of the distance measurement methods. However, it is known that the accuracy of distance measurement decreases due to various factors such as aging caused by vibration during driving and installation of the stereo camera, which causes the optical axis of the stereo camera to shift. In order to deal with such a decrease in accuracy, technology to correct the distance measurement system and improve the accuracy is also being considered.

[0003] For example, Patent Document 1 discloses a technology including: "an image input unit having a stereo camera for capturing an image in the direction of travel of a train, to which a pre-running binocular image captured by the stereo camera before the train runs and a running binocular image captured while the train runs; a landmark detection unit for detecting a plurality of landmarks around the train from the pre-running binocular image and detecting one landmark around the train from the running binocular image; and a calibration unit for performing a first calibration calculation on the pre-running binocular image based on position information of the plurality of landmarks around the train and performing a second calibration calculation on the running binocular image based on position information of the one landmark around the train, in which the calibration unit compares estimated position information of the one landmark around the train calculated from the running binocular image corrected based on the first calibration calculation performed before the train runs with reference position information which is a reference position of the one landmark around the train, and if the deviation amount of the estimated position information from the reference position information is equal to or greater than a threshold value, corrects the running binocular image based on the second calibration calculation." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 044564 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, in order to calibrate the forward monitoring device, it is necessary to obtain binocular images of the landmarks that serve as the reference for correction in advance, so the burden of advance preparation is large when performing the calibration. In addition, in the calibration of Patent Document 1, since the correction is relatively performed based on the information of the landmarks obtained in advance, if the accuracy of the information of the landmarks obtained in advance is low, there is a problem that the accuracy of the corrected distance measurement result also remains low. Therefore, an object of the present invention is to provide a technique for accurately detecting the accuracy of a distance measurement system without obtaining in advance a binocular image that serves as a reference for correction. [Means for solving the problem]

[0006] In order to solve the above problems, one representative distance measurement system of the present invention is a distance measurement system equipped with a rail information acquisition unit that acquires rail information from multiple directions and a distance calculation unit that performs distance calculation by stereo matching, and is characterized by comprising a rail unevenness information generation unit that detects unevenness on the rail and its surroundings, a first rail position detection unit that outputs the rail position based on the output of the rail unevenness information generation unit, a rail width calculation unit that outputs rail width information based on the output of the first rail position detection unit, a first rail distance calculation unit that outputs a first rail distance based on the rail width information, a second rail distance calculation unit that outputs a second rail distance based on the output of the distance calculation unit, a distance error calculation unit that compares the first rail distance with the second rail distance and outputs an error, and a correction amount calculation unit that outputs a correction amount for the output of the distance calculation unit based on the output of the distance error calculation unit. Effect of the Invention

[0007] According to the present invention, it is possible to provide a technique for accurately detecting the accuracy of a distance measurement system without obtaining in advance a binocular image that serves as a reference for correction. Problems, configurations and effects other than those described above will become apparent from the following description of the preferred embodiment of the invention. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating a distance measurement system according to a first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating the rail unevenness information generated by the rail unevenness information generating unit. [Diagram 3] FIG. 3 is a graph in which the four rows in FIG. 2 are extracted and the vertical axis represents the disparity value. [Figure 4] FIG. 4 is a diagram in which FIG. 2 is normalized and approximated by a straight line. [Diagram 5] FIG. 5 is a diagram in which the column addresses of each row in FIG. 4 are quantitatively shifted and rearranged. [Figure 6]FIG. 6 is a graph showing the region Y in FIG. [Figure 7] FIG. 7 is a cross-sectional view of the region X in FIG. 3 in the parallax value direction. [Figure 8] FIG. 8 is a diagram showing matters taken into consideration by the reliability evaluation unit. [Figure 9] FIG. 9 is a diagram showing the relationship between a distance measuring system mounted on a vehicle and a railroad track or road surface. [Figure 10] FIG. 10 is a flowchart showing the process in the distance measurement system. [Figure 11] FIG. 11 is a schematic diagram illustrating a distance measurement system according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiment. In addition, in the description of the drawings, the same parts are denoted by the same reference numerals. When there are multiple components having the same or similar functions, they may be described by using the same reference numerals with different subscripts, or when there is no need to distinguish between these multiple components, the subscripts may be omitted. In addition, although terms such as "first," "second," and "third" may be used in the present disclosure to describe various elements or components, it will be understood that these elements or components should not be limited by these terms. These terms are used only to distinguish one element or component from another element or component. Thus, a first element or component discussed below can also be referred to as a second element or component without departing from the teachings of the inventive concept. In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0010] [Example 1] In the first embodiment, an example of a distance measurement system equipped with a rail information acquisition unit will be described. In the first embodiment, a stereo camera is used as the rail information acquisition unit. First, each functional block will be described.

[0011] (composition) FIG. 1 is a diagram showing a schematic configuration of a distance measurement system 100 equipped with a rail information acquisition unit. The distance measurement system 100 includes a right camera 200, a left camera 300, a first geometric correction unit 201, a second geometric correction unit 301, a stereo matching unit 400, a distance calculation unit 410, a three-dimensional object detection unit 420, a rail unevenness information generation unit 500, a first rail position detection unit 510, a second rail position detection unit 600, a reliability evaluation unit 700, a rail width calculation unit 710, a first rail distance calculation unit 720, a distance error calculation unit 730, a correction amount calculation unit 740, and a second rail distance calculation unit 810. Thereby, the distance measurement system 100 measures the distance between the rails and the path of the vehicle on which it is mounted. Although the stereo camera is used as the distance measurement sensor serving as the rail information acquisition unit in the first embodiment, other distance measurement sensors may be used, for example, LiDAR (light detection and ranging).

[0012] The stereo camera includes two imaging units (a right camera 200 and a left camera 300) and generates images that are synchronously captured from different viewpoints. In other words, it functions as a rail information acquisition unit that acquires rail information of a rail acquired simultaneously from two different directions. Further, the right camera 200 constitutes a right-side camera as one of the imaging units of a stereo camera, and similarly, the left camera 300 constitutes a left-side camera as one of the imaging units of the stereo camera. In the first embodiment, the stereo camera is configured to include two imaging units, but may be configured to include any other number of imaging units.

[0013] The right camera 200 transmits a captured image to a first geometric correction unit 201. Similarly, the left camera 300 transmits a captured image to a second geometric correction unit 301.

[0014] The left camera 300 and the right camera 200 constitute a stereo camera, but can also be configured to function as a monocular camera by switching a switch or the like. This configuration is shown as an example, and the embodiment is not limited to this. A configuration in which a sensor for the stereo camera and a sensor for the monocular camera are provided separately may also be used.

[0015] The first geometric correction unit 201 corrects the image captured by the right camera 200 and transmits the corrected image to the stereo matching unit 400 . Specifically, first, the first geometric correction unit 201 performs distortion correction on the image captured by the right camera 200 to remove distortion in the image. This is because an image captured by a camera is generally distorted radially from the center of the image due to lens distortion, and similar distortion occurs in the image captured by the right camera 200, so that the distortion is prevented from affecting the generation of the disparity image by the stereo matching unit 400 described later.

[0016] Next, the first geometric correction unit 201 performs rectification so that corresponding points in the image captured by the right camera 200 and the image captured by the left camera 300 have the same row coordinates. This is because, as in this embodiment, when images captured by two imaging units at different angles or distances are superimposed, slight misalignment occurs, and by parallelizing the images in advance, the load on the stereo matching unit 400, which will be described later, is reduced.

[0017] The second geometric correction unit 301 corrects the image captured by the left camera 300 in the same manner as the first geometric correction unit 201 , and transmits the corrected image to the stereo matching unit 400 .

[0018] The stereo matching unit 400 generates a parallax image from the images corrected by the first geometric correction unit 201 and the second geometric correction unit 301 . Next, the stereo matching unit 400 generates a disparity image including a disparity value from the calculated disparity.

[0019] The distance calculation unit 410 generates a distance image from the parallax image generated by the stereo matching unit 400 . Specifically, the distance calculation unit 410 converts the parallax value of each pixel included in the parallax image into a distance based on the 2D3D conversion parameters, generates a distance image, and transmits it to the three-dimensional object detection unit 420. Furthermore, the distance calculation section 410 may generate a distance image taking into account the amount of correction calculated by the correction amount calculation section 740, as described below.

[0020] The three-dimensional object detection unit 420 detects a three-dimensional object, for example, an obstacle, from the range image. Specifically, the three-dimensional object detection unit 420 performs noise removal and grouping from three-dimensional coordinates including distance based on distance information included in the distance image, thereby detecting a three-dimensional object that is an obstacle to a traveling train.

[0021] The rail unevenness information generating unit 500 extracts the rail and its surrounding area from the parallax image generated by the stereo matching unit 400, and generates rail unevenness information based on the parallax value. At this time, the generated rail unevenness information is transmitted to the first rail position detection unit 510.

[0022] The first rail position detector 510 detects the rail position based on the detected unevenness of the rail. At this time, the detected rail position is set as the first rail position.

[0023] The second rail position detection unit 600 detects the rail position from the image captured by the left camera 300. At this time, the detected rail position is set as the second rail position. Specifically, the second rail position detection unit 600 may detect the position of the second rail from an image captured by the left camera 300 by machine learning. In addition, in the first embodiment, when the stereo camera generates a parallax image, the image captured by the left camera 300 is used as the reference image, and the rail position is detected from the image captured by the left camera 300. However, when the reference image is the right camera 200, it is desirable to detect the rail position from the image captured by the right camera 200 on the same side.

[0024] Furthermore, the second rail position detection unit 600 may detect the rail position using the parallax image as a simple image, or may detect the second rail position by searching for changes in color and contrast contained in the image.

[0025] The reliability evaluation unit 700 calculates the accuracy of the detected rail position as a reliability evaluation value, and if the reliability evaluation value is equal to or greater than a predetermined value, it determines that the detected rail position is reliable.

[0026] The rail width calculation unit 710 calculates the rail width based on the reliable rail position information transmitted from the reliability evaluation unit 700. That is, the rail width calculation unit 710 calculates the parallax image or the rail width on the image as the number of pixels based on the reliable rail position information transmitted from the reliability evaluation unit 700. The rail width is determined for each line on which the train runs, and the value can be obtained in advance. Therefore, the distance to the target rail portion can be calculated by knowing the difference between the column coordinates of the left rail and the column coordinates of the right rail, the focal length, and the standardized rail width. Also, the rail width may not be acquired as a value in advance, but may be calculated from the type of gauge of the railway track acquired. For example, if the acquired type of gauge is standard gauge, the rail width may be 1435 mm, and if it is narrow gauge, the rail width may be 1067 mm. Furthermore, the rail width may be acquired using information acquired during maintenance work on the line. In addition, the rail width calculation unit may calculate the rail width based on the rail position with higher reliability by setting a weight on at least one of the rail position determined by the first rail position detection unit 510 or the rail position determined by the second rail position detection unit 600 output by the reliability evaluation unit 700.

[0027] The first rail distance calculation unit 720 calculates the rail distance from the stereo camera to the rail based on the rail width based on the reliable rail position and the focal length of the stereo camera. At this time, the calculated rail distance is set as the first rail distance. Furthermore, the rail width calculation unit 710 outputs the rail width only when a reliable rail position is output from the reliability evaluation unit 700. For this reason, the rail width calculation unit 710 does not output the rail width at all times, and the rail width that is output becomes intermittent data. Therefore, the output of the first rail distance calculation unit 720, which receives the rail width as an input, is also intermittent, and becomes discontinuous information.

[0028] The second rail distance calculation unit 810 calculates the rail distance from the stereo camera to the rail using the parallax information. Specifically, the second rail distance calculation unit 810 obtains timing information when the first rail position is output from the first rail position detection unit 510, and in accordance with this timing, obtains rail distance information based on the distance image from the distance calculation unit 410 and outputs it to the distance error calculation unit 730. In other words, the second rail distance calculation unit 810 continuously calculates the second rail distance and transmits it to the distance error calculation unit 730.

[0029] The distance error calculation unit 730 calculates the difference between the first rail distance and the second rail distance.

[0030] The correction amount calculation unit 740 calculates a distance correction value based on the distance error information calculated by the distance error calculation unit 730 . The calculated distance correction value is transmitted to the distance calculation unit 410 and is used as a correction value when the distance calculation unit 410 calculates a distance image from the parallax value.

[0031] (Details of rail irregularities) Next, rail irregularity information will be described with reference to FIG. 2 and FIG. Fig. 2 is a diagram that illustrates rail unevenness information generated by the rail unevenness information generator 500. Fig. 3 is a graph in which four rows (row AA', row BB', row CC', and row DD') in Fig. 2 are extracted and plotted with the vertical axis representing the disparity value. The rail unevenness information generating unit 500 generates, as rail unevenness information, a diagram showing the distance from a stereo camera attached at a height of several meters above the road surface as parallax. For example, FIG. 2 is a diagram generated as rail unevenness information, and shows a parallax image when a stereo camera is attached to a vehicle at a height of 0.5 m above the ground. The diagram generated as rail unevenness information is a parallax image in which the larger the parallax value, the darker the color, and the smaller the parallax value, the lighter the color. Since parallax is larger in the foreground, the closer the area is, the lower the area in the drawing, the closer the area is to the left, and the darker the color is.

[0032] In FIG. 2, the upper surface of the rail 910 is located higher than the road surface 920, and in the row AA′ indicated by the chain line in FIG. 2, the rail 910 is depicted as standing out in a color closer to black than the road surface 920.

[0033] In addition, in FIG. 3 in which four rows (row AA', row BB', row CC', and row DD') in FIG. 2 are extracted with the horizontal pixel count on the horizontal axis and the disparity value on the vertical axis, the part indicated by area X in FIG. 2 is expressed with a changed disparity value as shown by area X in FIG. 3.

[0034] (Details of first rail position detection) Next, detection of the first rail position will be described with reference to FIGS. Fig. 4 is a diagram obtained by normalizing and linearly approximating Fig. 2. Fig. 5 is a diagram obtained by quantitatively shifting and rearranging the column addresses of each row in Fig. 4. Furthermore, FIG. 6 is a graph in which the region Y in FIG. 5 is enlarged and expressed as disparity values ​​for each pixel. The first rail position detector 510 detects the first rail position by detecting the outer and inner edges of the rail (the edges of the upper surface of the rail) based on the rail unevenness information. In detection using parallax, the position where the parallax changes can be detected with extremely high accuracy compared to the detection accuracy of the parallax value itself.

[0035] Therefore, by removing noise from the rail unevenness information as shown in FIG. 2, it is possible to detect the first rail position with high accuracy.

[0036] Specifically, the rail unevenness information generating unit 500 uses edge coordinates of different rows to generate rail unevenness information by normalizing the disparity value of each pixel by the road surface disparity of each row and linearly approximating it, as shown in FIG. 4. In other words, the road surface disparity is calculated from the disparity image, the road surface disparity is subtracted from the disparity value of each pixel in the disparity image, the approximate position of the rail is identified from a group of consecutive pixels having a disparity value that is positive or greater than a predetermined value, and the inner edge of the rail or the outer edge of the rail is detected from consecutive pixels around the approximate position of the rail whose disparity values ​​are negative or less than a predetermined value. This makes it possible to keep the edge threshold constant, and improves detection accuracy while reducing the load on first rail position detector 510 for detecting the first rail position.

[0037] As another method for improving detection accuracy, the rail unevenness information generating unit 500 may quantitatively shift and rearrange the column addresses of each row so that the rails are aligned vertically on the parallax image, as shown in FIG. 5. This allows the parallax values ​​to be added or averaged in the column direction.

[0038] For example, even if the disparity value does not indicate unevenness in region Y where line EE′ in FIG. 4 intersects with rail 910, the rearranged rail unevenness information, for example, in region Y in FIG. 5, stably indicates average rail unevenness as shown in FIG. 6. As a result, if the standard deviation in FIG. 6 is the minimum value, it can be determined that the quantitative value of the shifted column address is correct. On the other hand, since the standard for rail width is the width of the inside of the rail, the inside of the rail can also be detected as the rail position. In addition, there are cases where the rail edge positions in the parallax image do not match those in the image after geometric correction. In such cases, the rail unevenness information generator 500 needs to take into consideration, for example, correction according to the block size when the stereo matching unit 400 performs stereo matching.

[0039] (Details of the calculation of the reliability evaluation value) Next, the calculation of the reliability evaluation value will be described in detail with reference to FIG. Fig. 7 is a graph showing an overlapping display of the first rail position based on the unevenness of the rail detected by the first rail position detection unit 510 and the second rail position detected by the second rail position detection unit 600. In Fig. 7, the horizontal axis indicates the number of pixels in the horizontal direction, and the vertical axis indicates the disparity value. In FIG. 7, a solid line indicates a first rail position based on the unevenness of the rail detected by the first rail position detection unit 510, and a dashed line indicates a second rail position detected by the second rail position detection unit 600.

[0040] Since the first rail position is based on the unevenness of the rail, in FIG. 7, the outer and inner edge portions of the rail are shown as uneven portions where the disparity values ​​are higher than the road surface portion. In contrast, the position of the second rail is detected based on an image captured by the left camera 300, and is indicated by a dashed straight line in FIG.

[0041] The reliability evaluation unit 700 compares the first rail position with the second rail position, and if the difference between the first rail position and the second rail position, i.e., the relative position differences a, b in Figure 7, is less than a certain value, it determines that the reliability evaluation value is equal to or greater than a predetermined value, and determines that the rail position is a reliable rail position. Then, the reliability evaluation unit 700 outputs at least one of the rail position determined by the first rail position detection unit 510 or the rail position determined by the second rail detection unit as a reliable rail position.

[0042] When the rail width calculation unit 710 calculates the rail width based on reliable rail position information, the correction amount calculation unit 740 (described later) can generate a correction value with enough accuracy for use in the distance calculation unit 410.

[0043] In addition, in Fig. 7, the second rail position is located at a position less than a certain value from the uneven portion of the first rail position. However, if the second rail position is not located halfway between the outer and inner edges of the first rail position, but is located outside of it, the detected rail position is determined to be unreliable. In addition, the detected rail position may also be determined to be unreliable if the ratio of the second rail position's relative position a from the outside of the first rail position to its relative position b from the inside differs by a certain amount or more, or if the detected rail positions differ between the left and right rails.

[0044] In other words, when the second rail position is located less than a certain value away from the uneven portion of the first rail position, and the relative position a from the outside of the first rail position at the second rail position and the relative position b from the inside of the second rail position on the left and right rails do not differ by more than a certain value, the reliability evaluation unit 700 determines that the difference between the first rail position and the second rail position is less than a certain value, i.e., the reliability evaluation value is greater than or equal to a predetermined value.

[0045] Furthermore, the reliability evaluation section 700 may detect the position that is the center between the positions of both the inner and outer edges of the uneven portion of the first rail position as the first rail position. In this case, the difference between the first rail position and the second rail position is the difference between the center position and the second rail position. In this way, when the rail is positioned at the center of both edges, the rail width can be calculated as the width between the inner sides of the rail or the width between the outer sides of the rail from the relative distance between the left and right rail positions and the width of the top surface of the rail (a known value).Whether the width between the inner sides of the rail or the width between the outer sides of the rail is used can be appropriately selected according to the rail width definition information.

[0046] In addition, if the difference between the first rail position and the second rail position is greater than a certain value, i.e., the reliability evaluation value is less than a predetermined value, the reliability evaluation unit 700 stops outputting the rail position information, preventing unreliable rail position information from being transmitted to the rail width calculation unit 710.

[0047] Next, with reference to FIG. 8, the matters that the reliability evaluation section 700 takes into consideration when calculating the reliability evaluation value will be described. FIG. 8 is a diagram showing the items that the reliability evaluation unit 700 takes into consideration. In order to ensure the detection accuracy of the first rail position detection unit 510 and the second rail position detection unit 600, the reliability evaluation unit 700 may determine whether or not to calculate the reliability evaluation value by taking into account, for example, the weather, the time of day, the tilt of the sun, etc. In other words, as shown in FIG. 8, the reliability evaluation unit 700 is connected to components other than the first rail position detection unit 510 and the second rail position detection unit 600, such as the system controller 10, the right camera 200, and the stereo matching unit 400, and may calculate the reliability evaluation value taking into account information obtained from these components.

[0048] For example, the reliability evaluation unit 700 may be connected to the system controller 10 of the distance measurement system 100 and obtain external information a such as the vehicle position and time from the system controller 10, and use the fact that the position and time are suitable for obtaining rail position information to determine whether or not a reliability evaluation value can be calculated.

[0049] Similarly, the reliability evaluation unit 700 may obtain a condition b, such as day or night, backlight, etc., from an image obtained by the right camera 200, and determine whether or not a reliability evaluation value can be calculated.

[0050] Similarly, the reliability evaluation unit 700 may obtain a disparity value of the target area or an effective disparity rate c of the target area (the number of pixels for which correct disparity is obtained relative to the number of target pixels) from the disparity image obtained from the stereo matching unit 400, thereby improving the accuracy of the reliability evaluation value.

[0051] Similarly, the reliability evaluation unit 700 may calculate the reliability of the input second rail position based on the rail-related distance information d acquired from the second rail position detection unit 600, and take the reliability into consideration.

[0052] Furthermore, the reliability evaluation unit 700 may not calculate the difference between the first rail position and the second rail position, and depending on the environment, may decide to output either the first rail position or the second rail position as the reliable rail position.

[0053] Furthermore, the reliability evaluation unit 700 may change the selection and generation method of the information to be input and the information to be output.

[0054] For example, the reliability evaluation unit 700 may determine the straightness of the rail and the flatness of the road surface (presence or absence of undulations) from the rail positions detected by the first rail position detection unit 510 and the second rail position detection unit 600, and calculate the reliability evaluation unit 700 from the flat straight road that is most suitable for obtaining the rail position.

[0055] In either case, the reliability evaluation unit 700 may stop outputting data based on the information input to the reliability evaluation unit 700. Furthermore, the reliability evaluation unit 700 may store the calculated reliability evaluation value in a storage unit (not shown) in association with the first rail position or the second rail position, thereby making it possible to weight the reliability evaluation value in consideration of the associated value when recalculating the reliability evaluation value. Furthermore, the reliability evaluation value may be calculated by an external information processing device via a communication unit connected to the external information processing device, thereby reducing the load on the reliability evaluation unit 700. In addition, the information stored in the memory unit is not limited to the reliability evaluation value, and the data contained in the rail information acquisition unit, distance calculation unit 410, rail unevenness information generation unit 500, first rail position detection unit 510, reliability evaluation unit 700, rail width calculation unit 710, first rail distance calculation unit 720, second rail distance calculation unit 810, distance error calculation unit 730 and correction amount calculation unit 740 may be stored in association with at least one of the other data, and the data in the memory unit may be transmittable to the outside. Furthermore, the information processing performed by an external information processing device may be information processing performed by the distance calculation unit 410, the rail unevenness information generation unit 500, the first rail position detection unit 510, the reliability evaluation unit 700, the rail width calculation unit 710, the first rail distance calculation unit 720, the second rail distance calculation unit 810, the distance error calculation unit 730 and the correction amount calculation unit 740, and distance measurement may be performed based on the results performed by the external information processing device.

[0056] (Details of the second rail distance correction) Next, the details of the calculation of the distance error will be described with reference to FIG. FIG. 9 is a diagram showing the relationship between the distance measurement system 100 mounted on a vehicle and a railroad track or road surface. In the second rail distance calculation unit 810, since the area of ​​the upper surface of the rail is small, it is difficult to stably obtain the second rail distance, so the second rail distance is calculated by taking the distance from the road surface between the target rails. This allows the second rail distance calculation unit 810 to stably calculate the second rail distance. However, since the first rail distance calculation unit 720 calculates the first rail distance based on the parallax value, it calculates the distance from the rail top surface that is closest to the distance measurement system 100. Therefore, when the second rail distance and the first rail distance are compared as they are, a difference occurs between the distances because the end points to be measured are different. To prevent this, the second rail distance calculation unit 810 needs to correct the second rail distance and calculate the distance from the rail top surface in the same way as the first rail distance.

[0057] In FIG. 9, rails 910 are indicated by solid lines, and a road surface 920 is indicated by a dashed line. At this time, A shown in FIG. 9 indicates the distance between the distance measurement system 100 mounted on the train and the road surface 920, that is, the second rail distance. Also, B in FIG. 9 indicates the distance between the distance measurement system 100 mounted on the train and the upper surface of the rail 910, that is, the first rail distance.

[0058] Here, if the output of the second rail distance calculation unit 810 is Zb, the output of the first rail distance calculation unit 720 is Za, the camera height relative to the road surface is H, and the constant rail height is h, the corrected second rail distance Zb' is expressed by the following equation, and the final distance error is obtained by cutting off high frequencies using an LPF or the like. Zb = Zb / H (Hh) (1)

[0059] (Response to failure of the monitoring system disclosed herein) Next, the processing in the distance measurement system 100 will be described with reference to FIG. FIG. 10 is a flowchart showing the processing in the distance measurement system 100.

[0060] In step S101, the stereo matching unit 400 acquires an image captured by the right camera 200 and corrected by the first geometric correction unit 201 and an image captured by the left camera 300 and corrected by the second geometric correction unit 301.

[0061] In step S102, the stereo matching unit 400 generates a parallax image from the acquired images.

[0062] In step S103, the rail unevenness information generator 500 generates rail unevenness information from the parallax image.

[0063] In step S104, the rail position is detected. Specifically, the first rail position detection unit 510 detects the first rail position from the rail unevenness information, and the second rail position detection unit 600 detects the second rail position from an image captured by the left camera 300 and corrected by the second geometric correction unit 301.

[0064] In step S105, the reliability evaluation unit 700 compares the first rail position with the second rail position and determines a reliability evaluation value of the rail positions. If the reliability evaluation value is equal to or greater than the fixed value, the process proceeds to S106, and if it is less than the fixed value, the process ends.

[0065] In step S106, the rail width is calculated. Specifically, the rail width calculation section 710 calculates the rail width based on the first rail position or the second rail position transmitted from the reliability evaluation section 700.

[0066] In step S107, the first rail distance is calculated. Specifically, the first rail distance calculation unit 720 calculates the first rail distance based on the rail width.

[0067] In step S108, the second rail distance is calculated. Specifically, the second rail distance calculation unit 810 calculates the second rail distance based on the output of the distance calculation unit 410.

[0068] In step S109, the distance error is calculated. Specifically, the distance error calculation unit 730 compares the first rail distance with the second rail distance to calculate the distance error.

[0069] In step S110, the correction amount is calculated. Specifically, the correction amount calculation unit 740 calculates a distance correction value based on the distance error information calculated by the distance error calculation unit 730 .

[0070] In step S111, distance calculation section 410 corrects the distance measurement result based on the calculated distance correction value.

[0071] The distance measurement system 100 according to the first embodiment has been described above. The distance measurement system 100 of the present disclosure mainly has a first rail distance calculation unit 720 and a second rail distance calculation unit 810, and can accurately calculate a distance error by comparing the rail position based on unevenness information calculated from parallax, the first rail distance calculated based on the rail width that is accurately determined in advance by the standard, and the second rail distance calculated based on the parallax image, and can accurately correct the distance measurement of the distance measurement system 100 by calculating a correction amount based on the distance error.

[0072] [Example 2] Second Embodiment Next, a distance measurement system 100 according to a second embodiment will be described with reference to FIG. FIG. 11 is a schematic diagram illustrating a distance measurement system 100 according to the second embodiment. In the distance measurement system 100 of Example 1, the difference between the first rail distance and the second rail distance is treated as the distance error of the distance measurement system 100. However, the distance measurement system 100 of Example 2 differs from Example 1 in that the difference between the first rail distance and the second rail distance is treated as the parallax error of the distance measurement system 100. The distance measurement system 100 also includes a right camera 200, a left camera 300, a first geometric correction unit 201, a second geometric correction unit 301, a stereo matching unit 400, a distance calculation unit 410, a three-dimensional object detection unit 420, a rail unevenness information generation unit 500, a first rail position detection unit 510, a second rail position detection unit 600, a reliability evaluation unit 700, a rail width calculation unit 710, a first rail parallax calculation unit 721, a parallax error calculation unit 731, a correction amount calculation unit 741, and a second rail parallax calculation unit 811.

[0073] (Configuration example) The first rail parallax calculation unit 721 calculates the target rail parallax based on the rail width information sent from the rail width calculation unit 710. At this time, the calculated rail parallax is the first rail parallax. Specifically, the first rail parallax calculation unit 721 calculates the first rail parallax according to the following formulas (2) and (3), and transmits it to the parallax error calculation unit 731. Here, Rd is the first rail parallax, B is the baseline length of the stereo camera, fc is the focal length, Zb is the first rail distance, Rp is the pixel pitch, Rw is the rail width, and Rp is the number of pixels of the rail width on the image. Rd = B×fc / (Zb×Pp) ···(2) Zb = fc×Rw / Rp ···(3)

[0074] The second rail parallax calculation unit 811 calculates the rail parallax corresponding to the rail distance from the distance measurement system 100 to the rail using the parallax information. Specifically, the second rail parallax calculation unit 811 determines the target area from the distance image generated by the distance calculation unit 410, and calculates the distance of the rail in the target area. At this time, the calculated rail parallax is the second rail parallax. Similar to the second rail distance calculation unit 810, the target area is obtained from the first rail position detection unit 510.

[0075] The parallax error calculation unit 731 calculates the parallax error of the second rail parallax calculation unit 811. Specifically, the distance error calculation unit 730 calculates the difference between the first rail parallax and the second rail parallax as the parallax error.

[0076] The correction amount calculation unit 741 calculates the correction amount of the parallax of the stereo matching unit 400 based on the detection error. The calculated correction amount is transmitted to the stereo matching unit 400. The stereo matching unit 400 creates a distance image with the parallax value corrected based on the transmitted correction amount.

[0077] The distance measurement system 100 according to the second embodiment has been described above. The distance measurement system 100 of the present disclosure mainly has a first rail parallax calculation unit 721 and a second rail parallax calculation unit 811, and can calculate a parallax detection error by comparing a first rail parallax calculated based on a rail width defined by a standard with a second rail parallax calculated based on a parallax image, and can correct the parallax of the distance measurement system 100 by calculating a correction amount based on the detection error.

[0078] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention.

[0079] The present invention can also take the following forms. (Aspect 1) A distance measurement system including a rail information acquisition unit that acquires rail information from a plurality of directions and a distance calculation unit that performs distance calculation by stereo matching, a rail unevenness information generating unit that detects unevenness of the rail and its surroundings; A first rail position detection unit that outputs a rail position based on an output of the rail unevenness information generation unit; A rail width calculation unit that outputs rail width information based on an output of the first rail position detection unit; a first rail distance calculation unit that outputs a first rail distance based on the rail width information; a second rail distance calculation unit that outputs a second rail distance based on an output of the distance calculation unit; a distance error calculation unit that compares the first rail distance with the second rail distance and outputs an error; a correction amount calculation unit that outputs a correction amount for the output of the distance calculation unit based on an output of the distance error calculation unit; A distance measuring system comprising: (Aspect 2) A distance measurement system according to aspect 1, comprising: The rail information acquisition unit is a stereo camera, The rail unevenness information generation unit generates unevenness information based on a disparity image generated from an image of the stereo camera A distance measurement system characterized by this. (Aspect 3) A distance measurement system according to Aspect 1 or 2, comprising a reliability evaluation unit that determines the reliability of the rail position, and a second rail position detection unit that outputs the rail position from an image output by any of the rail information acquisition units, The reliability evaluation unit, compares the first rail position by the first rail position detection unit and the second rail position by the second rail position detection unit to calculate a reliability evaluation value of the rail position, and when the reliability evaluation value is equal to or greater than a predetermined value, outputs at least one of the first rail position or the second rail position as a reliable rail position A distance measurement system characterized by this. (Aspect 4) A distance measurement system according to Aspect 3, The reliability evaluation unit, calculates the reliability evaluation value based on at least one of the detected linearity or flatness of the rail, or the position of the vehicle traveling on the rail, weather, time, inclination of the sun, detection distance of the rail, disparity value or effective disparity rate between the rail and its surroundings A distance measurement system characterized by this. (Aspect 5) A distance measurement system according to Aspect 3 or 4, The first rail position detection unit, detects the inner edge position and the outer edge position of the rail, and outputs the position at the center thereof as the rail position, The rail width calculation unit, outputs the rail width information based on the rail position and information on the standardized rail width A distance measurement system characterized by this. (Aspect 6) A distance measurement system according to any one of aspects 2 to 5, The rail unevenness information generating unit The method is characterized in that a road surface parallax is output from the parallax image, and a parallax value of each pixel of the parallax image is normalized by the road surface parallax of each row and linearly approximated. Distance measuring system. (Aspect 7) A distance measurement system according to any one of aspects 3 to 6, The rail width calculation unit By setting a weight on at least one of the rail position detected by the first rail position detection unit and the rail position detected by the second rail position detection unit output by the reliability evaluation unit, The rail width is calculated based on the highly reliable rail position. Distance measuring system. (Aspect 8) A distance measurement system according to any one of aspects 3 to 7, a rail information acquisition unit and a second rail distance calculation unit that calculates a distance to the rail using the rail information, The distance measurement system, wherein the second rail distance calculation unit corrects the distance Zb acquired from the distance calculation unit to Zb' calculated based on the following formula (1). Zb = Zb / H (Hh) (1) Here, H is the camera height relative to the road surface, h is the rail height, and Zb' is the rail distance corrected for Zb. (Aspect 9) In the distance measurement system according to any one of aspects 3 to 8, a storage unit that stores data included in the rail information acquisition unit, the distance calculation unit, the rail unevenness information generation unit, the first rail position detection unit, the reliability evaluation unit, the rail width calculation unit, the first rail distance calculation unit, the second rail distance calculation unit, the distance error calculation unit, and the correction amount calculation unit in association with at least one other data, The data in the storage unit can be transmitted to an external device. Distance measuring system. (Aspect 10) In the distance measurement system according to any one of aspects 3 to 9, a communication unit capable of transmitting data included in the distance calculation unit, the rail unevenness information generation unit, the first rail position detection unit, the reliability evaluation unit, the rail width calculation unit, the first rail distance calculation unit, the second rail distance calculation unit, the distance error calculation unit, and the correction amount calculation unit to and from an outside; The system is characterized by being capable of measuring distances based on the results of external information processing. Distance measuring system. (Aspect 11) In the distance measurement system according to any one of aspects 1 to 10, The first rail distance calculation unit is a first rail disparity calculation unit that calculates a disparity corresponding to a distance to the rail based on the rail width information, The distance error calculation unit a parallax error calculation unit that compares a parallax output of the first rail parallax calculation unit with a parallax output obtained from a stereo matching unit, and outputs a parallax error; The correction amount calculation unit A correction amount for correcting the parallax information of a stereo matching unit is calculated based on the parallax error. Distance measuring system. (Aspect 12) A vehicle equipped with a distance measurement system according to any one of aspects 1 to 11. (Aspect 13) A distance measurement system including a rail information acquisition unit that acquires rail information from a plurality of directions and a distance calculation unit that performs distance calculation by stereo matching, A rail information acquisition unit acquires rail unevenness information that detects unevenness on the rail and its surroundings, Detecting a first rail position based on the rail unevenness information; Calculating a rail width based on the first rail position; outputting a first rail distance based on the rail width; Calculating a second rail distance based on an output of the distance calculation unit; Comparing the first rail distance and the second rail distance to calculate an error; Correcting the output of the distance calculation unit based on the error. A distance measuring method comprising: (Aspect 14) In the distance measuring method of aspect 13, The rail information acquisition unit is a stereo camera, Generate unevenness information based on a parallax image generated from the stereo camera image. A distance measuring method comprising: (Aspect 15) In the distance measuring method according to aspect 13 or 14, the distance measurement system includes a reliability evaluation unit that calculates a reliability evaluation value that determines the reliability of a rail position, and a second rail position detection unit that outputs a rail position from an image output by any of the rail information acquisition units, the reliability evaluation unit compares the first rail position with the second rail position to calculate a reliability evaluation value of the rail position; When the reliability evaluation value is equal to or greater than a predetermined value, the reliability evaluation unit outputs at least one of the first rail position and the second rail position as a reliable rail position. A distance measuring method comprising: [Explanation of symbols]

[0080] 10 System Controller 100 Distance Measuring System 200 Right Camera 300 Left Camera 201 First geometric correction section 301 Second Geometric Correction Section 400 Stereo Matching Section 410 Distance calculation section 420 Three-dimensional object detection unit 500 Rail unevenness information generation unit 510 First rail position detection unit 600 Second rail position detection unit 700 Reliability Evaluation Department 710 Rail width calculation section 720 First rail distance calculation unit 721 First rail parallax calculation unit 810 Second rail distance calculation unit 811 Second rail parallax calculation unit 730 Distance error calculation section 731 Parallax error calculation unit 740, 741 Correction amount calculation section 910 Rail 920 Road surface

Claims

1. A distance measurement system including a rail information acquisition unit that acquires rail information from a plurality of directions and a distance calculation unit that performs distance calculation by stereo matching, a rail unevenness information generating unit that detects unevenness of the rail and its surroundings; a first rail position detection unit that outputs a rail position based on an output of the rail unevenness information generation unit; a rail width calculation unit that outputs rail width information based on an output of the first rail position detection unit; a first rail distance calculation unit that outputs a first rail distance based on the rail width information; a second rail distance calculation unit that outputs a second rail distance based on an output of the distance calculation unit; a distance error calculation unit that compares the first rail distance with the second rail distance and outputs an error; a correction amount calculation unit that outputs a correction amount for the output of the distance calculation unit based on an output of the distance error calculation unit; A distance measuring system comprising:

2. 2. A distance measurement system according to claim 1, The rail information acquisition unit is a stereo camera, The rail unevenness information generating unit generates unevenness information based on a parallax image generated from the image of the stereo camera. A distance measuring system comprising:

3. 2. A distance measurement system according to claim 1, a reliability evaluation unit that determines the reliability of a rail position; and a second rail position detection unit that outputs a rail position from an image output by any one of the rail information acquisition units, The reliability evaluation unit is a first rail position detected by the first rail position detection unit and a second rail position detected by the second rail position detection unit are compared to calculate a reliability evaluation value of the rail position, and when the reliability evaluation value is equal to or greater than a predetermined value, at least one of the first rail position and the second rail position is output as a reliable rail position. A distance measuring system comprising:

4. 4. A distance measuring system according to claim 3, The reliability evaluation unit is The reliability evaluation value is calculated based on at least one of the detected straightness or flatness of the rail, the position of a vehicle traveling on the rail, the weather, the time, the inclination of the sun, the detected distance of the rail, the disparity value or the effective disparity rate of the rail and its surroundings. A distance measuring system comprising:

5. 4. A distance measuring system according to claim 3, The first rail position detection unit is Detecting the inner edge position and the outer edge position of the rail, and outputting the center position between them as the rail position; The rail width calculation unit Outputting the rail width information based on the rail position and the standardized rail width information A distance measuring system comprising:

6. 3. A distance measurement system according to claim 2, The rail unevenness information generating unit The method is characterized in that a road surface parallax is output from the parallax image, and a parallax value of each pixel of the parallax image is normalized by the road surface parallax of each row and linearly approximated. Distance measuring system.

7. 4. A distance measuring system according to claim 3, The rail width calculation unit By setting a weight on at least one of the rail position detected by the first rail position detection unit and the rail position detected by the second rail position detection unit, which are output by the reliability evaluation unit, The rail width is calculated based on the highly reliable rail position. Distance measuring system.

8. 4. A distance measuring system according to claim 3, a rail information acquisition unit and a second rail distance calculation unit that calculates a distance to the rail using the rail information, A distance measurement system characterized in that the second rail distance calculation unit corrects the distance Zb acquired from the distance calculation unit to Zb' calculated based on the following equation (1). Zb'=Zb / H・(HH)...(1) Here, H is the camera height relative to the road surface, h is the rail height, and Zb' is the rail distance corrected for Zb.

9. 4. The distance measurement system according to claim 3, a storage unit that stores data included in the rail information acquisition unit, the distance calculation unit, the rail unevenness information generation unit, the first rail position detection unit, the reliability evaluation unit, the rail width calculation unit, the first rail distance calculation unit, the second rail distance calculation unit, the distance error calculation unit, and the correction amount calculation unit in association with at least one other data, The data in the storage unit can be transmitted to an external device. Distance measuring system.

10. 4. The distance measurement system according to claim 3, a communication unit capable of transmitting data included in the distance calculation unit, the rail unevenness information generation unit, the first rail position detection unit, the reliability evaluation unit, the rail width calculation unit, the first rail distance calculation unit, the second rail distance calculation unit, the distance error calculation unit, and the correction amount calculation unit to and from an outside; The system is characterized by being capable of measuring distances based on the results of external information processing. Distance measuring system.

11. 2. The distance measurement system according to claim 1, The first rail distance calculation unit a first rail parallax calculation unit that calculates a parallax corresponding to a distance to the rail based on the rail width information, The distance error calculation unit a parallax error calculation unit that compares a parallax output of the first rail parallax calculation unit with a parallax output obtained from a stereo matching unit, and outputs a parallax error; The correction amount calculation unit A correction amount for correcting the parallax information of a stereo matching unit is calculated based on the parallax error. Distance measuring system.

12. A vehicle equipped with the distance measurement system according to any one of claims 1 to 11.

13. A distance measurement system including a rail information acquisition unit that acquires rail information from a plurality of directions and a distance calculation unit that performs distance calculation by stereo matching, A rail information acquisition unit acquires rail unevenness information that detects unevenness on the rail and its surroundings, Detecting a first rail position based on the rail unevenness information; Calculating a rail width based on the first rail position; outputting a first rail distance based on the rail width; Calculating a second rail distance based on an output of the distance calculation unit; Comparing the first rail distance and the second rail distance to calculate an error; Correcting the output of the distance calculation unit based on the error. A distance measuring method comprising:

14. 14. The distance measuring method according to claim 13, The rail information acquisition unit is a stereo camera, Generate unevenness information based on a parallax image generated from the stereo camera image. A distance measuring method comprising:

15. 14. The distance measuring method according to claim 13, the distance measurement system includes a reliability evaluation unit that calculates a reliability evaluation value that determines the reliability of a rail position, and a second rail position detection unit that outputs a rail position from an image output by any of the rail information acquisition units, the reliability evaluation unit compares the first rail position with the second rail position to calculate a reliability evaluation value of the rail position; When the reliability evaluation value is equal to or greater than a predetermined value, the reliability evaluation unit outputs at least one of the first rail position and the second rail position as a reliable rail position. A distance measuring method comprising:

Images