JP7405372B2 - marker - Google Patents

Description

The present invention relates to markers.

Conventionally, markers as described in Patent Document 1, for example, have been known. This marker is attached to the object in order to recognize the position, orientation, etc. of the object. By photographing a marker with a camera, the relative positional relationship between the camera and the marker can be recognized based on how the marker appears in the image.

JP2020-85771A

Here, the above-mentioned marker uses a lens member (lenticular lens) having a plurality of lens parts that are continuous in a plane direction in order to indicate the relative positional relationship between the camera and the marker. However, a marker using a lenticular lens has a problem in that it has a large number of parts, and it is necessary to align the parts with high precision.

An object of the present invention is to provide a marker that is easy to manufacture and that allows the position of the marker to be recognized with high accuracy.

A marker according to one aspect of the present invention is a marker that includes a position recognition part in which visual information observed changes depending on the direction of observation, and the position recognition part includes a permissive part that allows light to pass through and a light a first layer configured by a pattern of blocking portions that block the first layer; and a second layer provided on the back side of the first layer and having a member that can be visually recognized through the permitting portion. .

The position recognition section of the marker includes a first layer formed by a pattern of a permitting section that allows light to pass through and a blocking section that blocks light. Therefore, depending on the direction of observation, part of the light is blocked by the blocking part, and part of the light passes through the allowing part. Further, the position recognition section includes a second layer having a member that can be visually recognized via the allowance section. Therefore, the visual recognition aspect of the second layer changes based on the manner in which light passes through the first layer. Such a change in the recognition mode of the second layer can be used as visual information depending on the direction of observation, so it is possible to accurately recognize the position of the marker based on the visual information. Here, the position recognition section has a simple structure in which the second layer is provided on the back side of the first layer. Furthermore, since the recognition mode of the second layer can be adjusted by designing the pattern of the first layer, there is no need to precisely align the second layer with respect to the first layer. As described above, the position of the marker can be recognized with high precision while being easy to manufacture.

The second layer member may be a reflective member that reflects light. Thereby, the second layer can reflect the light that has passed through the permissive portion of the first layer and return it to the observation position. Therefore, the reflected light of the second layer becomes easier to see from the observation position, and the visibility of the visual information of the position recognition unit improves.

The reflective member may be a retroreflective member. Thereby, the second layer can reflect light from the observation position toward the observation position. Therefore, the reflected light of the second layer becomes more visible from the observation position, and the position recognition unit can further improve the recognition of visual information.

The allowing portion of the first layer may be formed by a slit formed between the pair of blocking portions. Therefore, the first layer can be formed by simply arranging a plurality of slits, which improves the ease of manufacturing.

The blocking part of the first layer is formed by a pattern of scattering parts formed on the front and back surfaces of the base material to scatter light, and the allowing part of the first layer is comprised of a pattern of light scattering parts formed on the front and back surfaces of the base material. It may be configured by a pattern of a transparent part with no part formed therein. Therefore, the first layer can be formed simply by forming a pattern of scattering parts on the front and back surfaces of the base material.

The permitting section may be configured to increase the inclination angle of light with respect to the thickness direction toward the outside as the distance from the central position of the position recognition section increases. Such a configuration is suitable for obtaining changes in visual information to be observed depending on the direction of observation.

According to the present invention, it is possible to provide a marker that is easy to manufacture and that allows the position of the marker to be recognized with high accuracy.

FIG. 3 is a diagram showing how a marker is used according to the present embodiment. FIG. 2 is a perspective view showing a marker according to the present embodiment. 3(a) is a sectional view taken along the line IIIa-IIIa shown in FIG. 2, and FIGS. 3(b), 3(c), and 3(d) are enlarged sectional views of the slit. FIG. 6 is a diagram showing the angle of the camera with respect to the marker and how the position recognition unit looks at the angle. FIG. 12 is a schematic diagram showing a pattern of a permissible portion of a marker according to a modified example. FIG. 5 is a schematic diagram showing a change in visual information of a pattern corresponding to FIG. 5(a). FIG. 5 is a schematic diagram showing how the visual information of the pattern changes corresponding to FIG. 5(d). FIG. 5 is a schematic diagram showing how the visual information of the pattern changes corresponding to FIG. 5(i). FIG. 7 is a schematic diagram showing how visual information of a marker changes according to a modified example. FIG. 7 is a schematic diagram showing how visual information of a marker changes according to a modified example. 11(a) and 11(b) are enlarged cross-sectional views showing an allowable part and a blocking part of a marker according to a modified example, and FIGS. 11(c), (d), and (e) are enlarged sectional views showing structural examples of a scattering part. It is a diagram.

Embodiments of the present invention will be described in detail below with reference to the drawings. In addition, in the drawings, the same or equivalent elements are given the same reference numerals, and overlapping explanations will be omitted.

FIG. 1 is a diagram showing how a marker 1 according to this embodiment is used. FIG. 1 shows a situation when a forklift 100 approaches a cargo handling object 101 in order to handle the cargo handling object 101. A marker 1 is attached to the cargo handling object 101. The forklift 100 includes a camera 102 and a calculation device 103. The camera 102 photographs the cargo handling object 101. Note that the camera 102 has a light that can irradiate the observation range with light. The calculation device 103 calculates the positional relationship between the forklift 100 and the marker 1 based on the image of the marker 1 among the images taken by the camera 102. Thereby, the calculation device 103 calculates the positional relationship between the forklift 100 and the cargo handling object 101.

FIG. 2 is a perspective view showing the marker 1 according to this embodiment. As shown in FIG. 2, the marker 1 is a plate-like member having a substantially rectangular shape. The marker 1 includes a mark section 2, a reference point 3, and a position recognition section 4 on its surface. Note that the arrangement, shape, etc. of the mark section 2, reference point 3, and position recognition section 4 are merely examples, and can be changed as appropriate. Furthermore, the marker 1 is constructed by laminating the main body portion 10 and the base member 11. The main body portion 10 is a plate-shaped molded part formed by injection molding or the like. The resin material of the main body portion 10 is preferably thermoplastic resin from the viewpoint of forming slits to be described later, but thermosetting resin may also be used. The base member 11 is a plate-shaped component that is laminated on the back surface of the main body portion 10 .

The mark portion 2 is formed in a central region of the surface of the main body portion 10 . The mark section 2 is a section that displays a predetermined pattern or the like. These symbols function as identification information by being linked to the ID number of the cargo handling object 101, etc. For example, when the camera 102 detects a predetermined pattern on the mark section 2, the calculation device 103 can identify the cargo handling object 101 by searching for the ID number linked to the pattern (see FIG. 1). . The mark portion 2 is formed, for example, by pasting a sheet with a pattern printed on the main body portion 10. The design of the mark part 2 may be shown in a predetermined color or may be shown by a retroreflective member.

The reference points 3 are formed at the four corners of the surface of the main body part 10. The reference point 3 is shown as a figure with a shape and size that is easy to recognize in the image, and in the example of FIG. 2, it is shown as a colored circle. The method of forming the reference points 3 is not particularly limited, but for example, a sheet may be attached to the surface of the main body 10, the surface may be colored, or a through hole may be provided in the main body 10 to set the color of the base member 11 to the reference points 3. May be used as a color. Further, the reference point 3 may be shown in a color opposite to that of the main body 10, or may be shown by a retroreflective member. For example, when the camera 102 detects the reference point 3, the arithmetic unit 103 recognizes the positional relationship between the marker 1 and the forklift 100 based on the reference point 3 in the image (see FIG. 1).

The position recognition unit 4 is a part in which visual information observed changes depending on the direction of observation. That is, visual information that can be acquired from the position recognition unit 4 in the image captured by the camera 102 changes depending on the positional relationship between the marker 1 and the camera 102. Details of the recognition information obtained by the position recognition unit 4 will be described later. The position recognition section 4 is formed on the surface of the main body section 10 at a position along the edge. The position recognition unit 4 is formed between the pair of reference points 3. One position recognition section 4A is provided at a position corresponding to one side of the main body 10, and another position recognition section 4B is provided at a position corresponding to another side orthogonal to the side. When the marker 1 is attached to the cargo handling object 101, one of the position recognition parts 4A is arranged to extend in the left-right direction D1, and the other position recognition part 4B is arranged to extend in the up-down direction D2. Thereby, one of the position recognition units 4A can indicate visual information that can obtain the relative angle between the marker 1 and the camera 102 in the left-right direction D1. Further, the other position recognition unit 4B can display visual information that allows acquisition of the relative angle between the marker 1 and the camera 102 in the vertical direction D2. As a result, when the camera 102 detects an image of each position recognition unit 4A, 4B, the arithmetic unit 103 calculates the horizontal direction D1 between the camera 102 and the marker 1 based on the visual information that can be acquired from each position recognition unit 4. and a relative angle in the vertical direction D2 to recognize the positional relationship between the marker 1 and the forklift 100. In the example shown in FIG. 2, two position recognition units 4 are formed, but the number is not particularly limited. Moreover, although the position recognition part 4 exists on the same plane as the mark part 2, the position recognition part 4 may protrude or be recessed.

FIG. 3(a) is a cross-sectional view taken along the line IIIa-IIIa shown in FIG. FIG. 3A shows a cross-sectional structure of a position recognition unit 4A for obtaining the relative angle in the left-right direction D1 between the marker 1 and the camera 102. Therefore, in the following description, when words such as "left-right direction D1" and "up-down direction D2" are used, the directions are based on the attitude when the marker 1 is attached to the cargo handling object 101. Note that the position recognition unit 4B for acquiring the relative angle in the vertical direction D2 between the marker 1 and the camera 102 has the same configuration as the position recognition unit 4A except that the direction is different.

As shown in FIG. 3A, the position recognition unit 4A includes a first layer 20 and a second layer 30. The first layer 20 is a layer constituted by the main body portion 10. The second layer 30 is a layer provided on the back surface side of the first layer 20, and is a layer composed of the base member 11. In the following explanation, when viewed from the camera 102, the angle when the camera 102 tilts to the left with respect to the marker 1 is referred to as a negative (minus) angle, and the angle when the camera 102 tilts to the right is referred to as a positive (plus). It will be explained as the angle of Note that the state perpendicular to the surface of the marker 1 is assumed to be "angle = 0°."

The first layer 20 is composed of a pattern of allowing portions 21 that allow light to pass through and blocking portions 22 that block light. The allowable portion 21 is constituted by a penetrating portion that penetrates the main body portion 10 in the thickness direction D3, and allows light to pass through the penetrating portion. The blocking portion 22 is constituted by the remaining meat around the penetrating portion of the allowing portion 21 . In this embodiment, the allowing portion 21 is formed by a slit 23 formed between a pair of blocking portions 22 . The slits 23 extend in the vertical direction D2 (see FIG. 2) and are arranged in the horizontal direction D1. At this time, the blocking section 22 is configured as a beam member extending in the vertical direction. The blocking portion 22 is preferably formed of a black resin or the like in order to make it easier to see reflected light, which will be described later, in an image. Note that the allowing part 21 and the blocking part 22 may be formed integrally with other parts of the main body part 10. In this case, if the blocking part 22 is molded from black resin, the other parts of the main body part 10 will also be black. However, the resin member constituting the first layer 20 does not need to be integrally molded with other parts of the main body 10, and can be molded separately and fitted into corresponding parts of the main body 10. You may also do so. Furthermore, the slits 23 of the first layer 20 do not need to be formed by molding, and may be formed by processing.

Regarding the shape of the slit 23 described above, if the length of the penetrating portion penetrating in the thickness direction D3 is five times or more as long as the length of the permissible portion 21, efficient angle recognition becomes possible. Furthermore, considering processability such as moldability, the size of the allowable portion 21 is preferably about 0.3 to 1 mm, and the length of the penetrating portion penetrating in the thickness direction D3 is about 1.5 to 10 mm. It is desirable that the aspect ratio is 5 to 10. Further, it is preferable that the adjacent angles be set in 1 to 5° increments.

The cross-sectional shape of the slit 23 is configured such that the inclination angle with respect to the thickness direction D3 changes depending on the position in the left-right direction D1. In this embodiment, the slit 23A at the center in the left-right direction D1 extends parallel to the thickness direction D3. The farther left the slit 23 is from the central slit 23A, the more the slit 23 inclines to the left and the negative angle becomes larger. Furthermore, the farther the slit 23 is to the right from the central slit 23A, the more the slit 23 inclines to the right and the larger the positive angle becomes. As an example, the width of the slit 23 is preferably 0.3 mm, and the height (dimension in the thickness direction D3) is preferably 3 mm, but as described above, it may be larger or smaller than these values. Note that the side walls of the slit 23 (the side walls of the pair of blocking parts 22) do not need to be parallel to each other, and may be given a taper angle.

The angle of inclination of each slit 23 is set according to the angle of light that is allowed to pass through. For example, the slit 23A located at the center in the left-right direction D1 is configured to allow light of "-1° to +1°" as shown in FIG. 3(b). The slit 23, which is formed slightly to the right of the central slit 23A, is formed to be inclined to the right, as shown in FIG. 3(c), and allows light from 0° to +2°. configured to do so. The slit 23 formed on the left side of the slit 23A at the central position is formed so as to be inclined to the left as shown in FIG. 3(d), and allows light of "-6° to -4°". configured to do so.

With the above configuration, as shown in FIG. 3(a), when the light IL1 enters the first layer 20 at an angle of 0°, the light IL1 passes through the slit 23 with a small angle near the center position. and reaches the second layer 30. On the other hand, the light IL1 that is incident on the slit 23 at a large angle away from the central position collides with the blocking portion 22 and is blocked without reaching the second layer 30. When the light IL2 tilted to the left is incident on the first layer 20, the light IL2 passes through the slit 23 near the left end, which is away from the center position to the left, and reaches the second layer 30. On the other hand, the light IL2 incident on the slit 23 at positions other than the left end collides with the blocking portion 22 and is blocked without reaching the second layer 30.

The second layer 30 is made of a reflective member that reflects light. In this embodiment, the reflective member is a retroreflective member 31. The retroreflective member 31 is a reflective member that uses the principle that when light is incident, it reflects the light toward the position from which the light has entered. The retroreflective member 31 may be constructed by attaching a retroreflective tape to the back surface of the first layer 20. Note that the entire base member 11 may be constituted by the retroreflective member 31, or the retroreflective member 31 may be provided only at the position of the position recognition section 4.

For example, when light IL1 with a small angle enters the slit 23 near the center position, reflected light RL1 with the same angle is reflected to the outside through the slit 23. When the light IL2 inclined to the left enters the slit 23 near the left end, the reflected light RL2 at the same angle is reflected to the outside through the slit 23.

Here, the structures of the allowing part 21 and the blocking part 22 are not limited to those described above, and as another structure, a blocking effect based on a scattering effect of transmitted light using an uneven structure may be used. In this case, a scattering part mask pattern is formed on the front and back surfaces of the base material of the first layer 20 so that the allowing part 21 and blocking part 22 corresponding to the pattern of the slits 23 described above can be formed. Moreover, the mask patterns on the front and back surfaces of such a base material allow light to pass through at corresponding angles. Therefore, by forming a mask pattern with a concavo-convex structure corresponding to the transmission and blocking of the pattern of the slits 23 on the front and back surfaces of the base material of the first layer 20, and arranging a plurality of them, the first mask pattern has the same effect as the pattern of the slits 23. Since the layer 20 can be formed, ease of manufacture is improved.

An example of a structure using such a mask pattern will be described with reference to FIG. 11(a). As shown in FIG. 3, the blocking section 22 of the first layer 20 is constituted by a pattern of scattering sections 61 that are formed on the front surface 60a and the back surface 60b of the transparent base material 60 and scatter light. Further, the permissive portion 21 of the first layer 20 is configured by a pattern of a transparent portion 62 on the front surface 60a and back surface 60b of the base material 60, on which the scattering portion 61 is not formed. That is, since light has the characteristic of traveling in a straight line, the front surface 60a and back surface 60b of the base material 60 are provided with transmitting portions 62 and scattering portions corresponding to the arrangement pattern of the slits 23 and blocking portions 22 shown in FIG. 3(a). A section 61 is formed. In this way, the patterns of the allowing portion 21 and the blocking portion 22 can be realized by determining the angle of transmission and scattering using the mask patterns formed on the front surface 60a and the back surface 60b. Specifically, by providing an uneven structure on the front surface 60a and the back surface 60b of the base material 60 in accordance with the mode of allowing and blocking light in the slit pattern described above, the first layer 20 is A mask pattern is formed that can obtain a light blocking effect at the boundary of the . The portion where the uneven structure is formed corresponds to the scattering portion 61, and the portion where the uneven structure is not formed and is a smooth plane corresponds to the transmitting portion 62. Note that the light-blocking portions on the front surface 60a and back surface 60b of the base material 60 are not limited to those having a concave-convex structure that block light by a scattering effect, but may be formed of a coating film or the like. In this case, similar light blocking is possible due to the light absorption effect.

Specifically, light incident from the surface 60a side enters into the base material 60 from the transmitting portion 62 of the surface 60a. Of the incident light, the light IL3 can be emitted from the transmission section 62 on the back surface 60b and can be reflected by the second layer. On the other hand, the light IL4 is scattered by the scattering portion 61 on the back surface 60b, and therefore cannot be reflected by the second layer. Therefore, the area sandwiched by the straight line (the straight line indicated by the dashed-dotted line) connecting the edges on both sides of the transparent part 62 on the front surface 60a and the edges on both sides of the transparent part 62 on the back surface 60b corresponds to the permissible part 21. . The shape, arrangement, etc. of this allowable portion 21 correspond to the slit 23 in FIG. 3(a). The area of the base material 60 other than the allowable part 21 corresponds to the blocking part 22 . The shape, arrangement, etc. of the blocking section 22 correspond to the blocking section 22 formed of the beam member shown in FIG. 3(a).

The uneven structure of the scattering section 61 only needs to have the function of enhancing the light scattering effect and attenuating the transmitted component. It is sufficient that the size of the concavo-convex structure has an average spacing greater than the wavelength of light, and the height has a height greater than the average spacing of the structures. Specifically, in the case of a visible wavelength band of 400 nm to 700 nm, an effective light blocking effect can be obtained if the average spacing of the structures is 400 nm or more and the height is 400 nm or more. Further, the larger the structure, the more desirable the scattering effect, and the average spacing between the structures can be effectively exhibited up to about 100 μm to 300 μm. More preferably, the average spacing between the structures is 80 μm, the diameter of the structures is 40 μm, and the height is 40 μm or more. Further, these structures, the allowing portion 21, and the blocking portion 22 may be formed integrally with other portions of the main body portion 10. In this case, the allowing part 21 and the blocking part 22 can function even if they are made of the same material. However, it is desired that the resin member constituting the first layer 20, that is, the base material 60, transmit the wavelength of the target light.

Note that the shape of the uneven structure of the scattering portion 61 is not particularly limited, and may be square, chevron-shaped, wave-shaped, etc. as shown in FIGS. may be adopted.

Furthermore, when using the blocking effect due to the scattering effect of transmitted light using the uneven structure, the plurality of transmitting parts 62 and scattering parts 61 formed on the front surface 60a of the base material 60 are formed on the back surface 60b. It is also possible to make one pattern correspond to the other. In this case, when a retroreflective member is used for the second layer, the light emitted from the observation point passes through a plurality of transmitting parts 62 formed on the front surface 60a of the first layer 20 and a plurality of transmitting parts 62 formed on the back surface 60b. The transmission mode is determined by the positional relationship of the transmission portions 62. The light incident from the observation point can be returned to the observation point by the retroreflection member, allowing visual information to be recognized by the position recognition unit. Moreover, in the case of this structure, the ease of manufacture is further improved.

Specifically, a structure as shown in FIG. 11(b) may be adopted. In this configuration, one transparent portion 62 is formed at the center of the surface 60a, and additional transparent portions 62 are formed side by side on the left and right sides. On the other hand, on the back surface 60b, a transmission section 62A is formed at the center position, but no transmission section 62 is formed at a position facing the left and right transmission sections 62 on the front surface 60a. In such a configuration, the first permissive part 21 is formed between the transparent part 62 at the center position of the front surface 60a and the transparent part 62A of the back surface 60b, and the first permissible part 21 is formed between the transparent part 62 on the left side of the front surface 60a and the transparent part 62A of the back surface 60b. A second permissible part 21 is formed between the transparent part 62A on the right side of the front surface 60a and a third permissible part 21 between the transparent part 62 on the right side of the front surface 60a and the transparent part 62A on the back surface 60b. In this case, when a retroreflective member is used for the second layer, the light emitted from the observation point is transmitted through the plurality of transmission parts 62 formed on the front surface 60a and the transmission part 62A formed on the back surface 60b. The transmission mode is determined by the positional relationship. The light incident from the observation point can be returned to the observation point by the retroreflection member, allowing visual information to be recognized by the position recognition unit. Moreover, in the case of this structure, it is possible to improve the ease of manufacturing and the accuracy of polygonal detection.

What kind of vision can be obtained by the position recognition unit 4A having the above configuration will be explained with reference to FIG. 4. FIG. 4 is a diagram showing the angle of the camera 102 with respect to the marker 1 and how the position recognition unit 4A looks at the angle. When the camera 102 photographs the position recognition unit 4A while irradiating it with light, reflected light is emitted by retroreflection at a position corresponding to the slit 23 through which the light has passed. Therefore, in the image, a streak of light as if the corresponding slit 23 emitted light can be seen. Note that since reflected light is not emitted in areas other than where the light streak is confirmed, the position recognition unit 4A is shown in its original color in the image. A portion of the position recognition unit 4A that is shown in a manner different from other positions, such as a light streak caused by such reflected light, may be referred to as a characteristic portion 40. In addition, in FIG. 4, in order to facilitate understanding, portions where light is strong are shown in black. In an actual image, the black streaks are confirmed as streaks of light.

Specifically, as shown in FIG. 4A, when the angle of the camera 102 with respect to the marker 1 is 0°, the characteristic part 40 is confirmed near the center position of the position recognition part 4A. Then, as the angle of the camera 102 with respect to the marker 1 increases to the right (that is, to the + side), the characteristic portion 40 moves to the right. In this way, the position recognition unit 4A can indicate the position where the characteristic part 40 is confirmed as visual information. In the position recognition unit 4A, the position of the observed characteristic portion 40 changes depending on the direction of observation.

Next, the functions and effects of the marker 1 according to this embodiment will be explained.

The position recognition section 4 of the marker 1 includes a first layer 20 configured by a pattern of a permitting section 21 that allows light to pass through and a blocking section 22 that blocks light. Therefore, depending on the direction of observation, part of the light is blocked by the blocking part 22 and part of the light passes through the allowing part 21. Further, the position recognition section 4 includes a second layer 30 having a member (retroreflective member 31 in this case) that can be visually recognized via the allowing section 21 . Therefore, the visual recognition aspect of the second layer 30 changes based on the manner in which light passes through the first layer 20. Here, the retroreflective member 31 at the location where the light is reflected is visually recognized as glowing. Such a change in the recognition mode of the second layer 30 can be used as visual information depending on the direction of observation, so it becomes possible to accurately recognize the position of the marker 1 based on the visual information. .

Here, the position recognition unit 4 has a simple structure in which the second layer 30 is provided on the back side of the first layer 20. Furthermore, since the recognition mode of the second layer 30 can be adjusted by designing the pattern of the first layer 20, there is no need to precisely align the second layer 30 with respect to the first layer 20. . As described above, the position of the marker can be recognized with high precision while being easy to manufacture.

For example, as a comparative example, a marker using a lenticular lens as a position recognition section will be described. In this case, it is necessary to print a checkable mark or the like on the lenticular lens at the condensing position. In this case, the position of the mark and the position of the lenticular lens must be precisely aligned, which takes time and effort to manufacture. In addition, a lenticular lens and parts related to the lenticular lens must be prepared separately from the resin molded product of the main body, which increases the number of parts. On the other hand, in the present embodiment, the position recognition unit 4 can detect the second layer 30 having the retroreflective member 31 even if the first layer 20 and the second layer 30 are not precisely aligned. It can be easily manufactured by simply covering the first layer 20. Further, the number of parts can be reduced because it is sufficient to integrally mold the slit pattern on the main body 10 without preparing special parts such as a lenticular lens.

The second layer 30 may be made of a reflective member that reflects light. Thereby, the second layer 30 can reflect the light that has passed through the allowing portion 21 of the first layer 20 and return it to the observation position. Therefore, since the reflected light of the second layer 30 is easily seen from the observation position, the visibility of the visual information of the position recognition unit 4 is improved.

The reflective member may be a retroreflective member 31. Thereby, the second layer 30 can reflect light from the observation position toward the observation position. Therefore, since the reflected light of the second layer 30 is more easily seen from the observation position, the visual information recognition ability of the position recognition unit 4 is further improved. Furthermore, when the retroreflective member 31 is used, the light from the camera 102 can be used for visual information in the position recognition unit 4, so the influence of external disturbances (for example, in a dark place) can be reduced. It can be used at any time.

The allowing portion 21 of the first layer 20 may be formed by a slit 23 formed between a pair of blocking portions 22 . Therefore, the first layer 20 can be formed by simply arranging a plurality of slits 23, which improves the ease of manufacturing.

The blocking part 22 of the first layer 20 is formed by a pattern of scattering parts 61 that scatter light formed on the front surface 60a and the back surface 60b of the base material 60. Of the front surface 60a and the back surface 60b of 60, the pattern may include a transmitting portion 62 on which the scattering portion 61 is not formed. Therefore, the first layer 20 can be formed simply by forming the pattern of the scattering portions 61 on the front surface 60a and the back surface 60b of the base material 60.

The permitting section 21 may be configured to increase the inclination angle of the light that is allowed to pass toward the outside with respect to the thickness direction D3 as the distance from the central position of the position recognition section 4 increases. Such a configuration is suitable for obtaining changes in visual information to be observed depending on the direction of observation.

Note that when the retroreflective member 31 is used as the second layer 30, the light emitted from the observation point passes through the first layer 20, is reflected by the second layer 30, and cannot be returned to the observation point. Therefore, it is possible to process images according to the emission pattern of the observation point. For example, by processing the received light image pattern obtained from the intensity pattern and wavelength pattern of light emitted from an observation point and performing differential processing, the influence of disturbance noise can be reduced, and during the day, etc. Efficient recognition is possible even in environments with strong ambient light noise.

In addition, the intensity pattern of the light emitted from the observation point is such that the time for obtaining the human afterimage effect is between 50 ms and 100 ms, so if the pulse emission time is 50 ms or less and the interval is 100 ms or more, Since it becomes difficult for the human eye to recognize the luminescent phenomenon, it also has the advantage of not interfering with the field of view of the work vehicle. On the other hand, when the pulse emission time is 50 ms or more and the interval is 100 ms or less, it can appear as if the light is always shining to the human eye.

The invention is not limited to the embodiments described above.

For example, in the above-described embodiment, the retroreflective member 31 is employed as a member of the second layer 30, but the retroreflective member 31 is not particularly limited as long as it is a member that can be visually recognized through the allowing portion 21. For example, a simple reflective member such as a mirror or mirror-finished metal may be used as the second layer 30. On the other hand, as the second layer 30, a reflective member using a scattering phenomenon due to reflection may be employed, using a surface coated with a metal in a frosted glass-like structure such as an uneven structure. Alternatively, a member having a color opposite to that of the first layer 20 may be employed as the second layer 30. In this case, in the feature 40 shown in FIG. 4, the color of the second layer 30 can be visually recognized in the image.

Further, the visual information of the position recognition unit 4 is not limited to that obtained from the straight slit arrangement pattern as described above. For example, a position recognition unit 4 as shown in FIG. 5 may be employed. FIG. 5 shows the shape and arrangement pattern of the allowable portion 21 when viewed from the camera 102 side.

As shown in FIGS. 5(a) and 5(b), the allowing portion 21 may have a V-shaped bend. Further, as shown in FIG. 5(c), the allowing portion 21 may have a C-shaped curve. FIG. 6 shows how the characteristic portion 40 changes in the pattern of FIG. 5(a). As shown in FIG. 6(a), when the camera 102 is at 0°, the characteristic portions 40 are confirmed in the allowing portions 21 facing each other at the center position. As shown in FIG. 6(b), when the camera 102 is tilted diagonally to the right, the characteristic portion 40 moves to the right.

As shown in FIG. 5(d), the allowable portion 21 may form a matrix pattern of dots. In this case, as shown in FIG. 7, various patterns of changes in visual information can be adopted. For example, as shown in FIG. 7A, when the camera 102 is at 0°, the characteristic portion 40 is confirmed by the dots in the central row. As shown in FIG. 7B, when the camera 102 is tilted diagonally to the right, the characteristic portion 40 moves to the right. Alternatively, the feature portion 40 may move in a meandering zigzag manner depending on the angle of the camera 102, as shown by the broken line arrow in FIG. 7(c). For example, as shown in FIG. 7C, the feature portion 40 that is located at the center when the camera 102 is at 0° may move to the right as the camera 102 moves diagonally to the right. (See Figure 7(d)). Further, as shown by the broken line arrow in FIG. 7(e), the characteristic portion 40 may meander back and forth depending on the angle of the camera 102. For example, as shown in FIG. 7(e), when the camera 102 is at 0°, the feature portion 40 that is placed in the top row at the center position changes to the top row as the camera 102 moves diagonally to the right. It may be moved to the right side of the lower row (see FIG. 7(f)).

In addition, various variations may be adopted as the shape of the allowable portion 21. For example, as shown in FIGS. 5(e) and 5(f), a diamond-shaped allowance portion 21 may be adopted, or as shown in FIG. 5(g), an elliptical allowance portion 21 may be adopted. 5(h), a rectangular permitting portion 21 may be adopted.

Further, as shown in FIG. 5(i), the visual information may be changed by mixing the shapes of the allowing portions 21. For example, as shown in the top row of FIG. 8, when the camera 102 is at 0°, the characteristic portion 40 is confirmed at the center position, and circular characteristic portions 141A and 141B are confirmed at the left and right ends. At this time, the feature section 40 that moves left and right indicates the absolute value of the angle, the feature section 141A on the right side indicates that the angle is a positive value, and the feature section 141B on the left side indicates that the angle is a negative value. You can show it. Therefore, since the second and third rows have a common absolute value of "1°", the position of the characteristic part 40 is the same, but in the second stage, which has a positive angle, the characteristic part 141A on the right side is confirmed, In the third row, which is at a negative angle, the characteristic portion 141B on the left side is confirmed. At the fourth stage, the absolute value is as large as "5°", so the characteristic portion 40 moves largely toward the end.

Furthermore, the shape and arrangement of the feature parts that move depending on the angle of the camera 102 are not particularly limited. For example, as shown in FIG. 9A, the slit shapes may be arranged vertically (in a vertical arrangement), so that the characteristic portion 40 may move in the vertical direction depending on the angle. Further, as shown in FIG. 9(b), the slit shapes may be arranged in two rows. For example, a negative angle may cause the feature 40 to move in the upper row, and a positive angle may cause the feature 40 to move in the lower row.

Further, not only visual information in which the feature parts 40 move according to the angle, but also visual information in which the pattern of the arrangement of the plurality of feature parts 40 changes depending on the angle may be adopted. For example, as shown in FIG. 10(a), the plurality of feature parts 40 may change the two-dimensional pattern depending on the angle. Further, the shape itself of the feature portion 40 may change depending on the angle. For example, as shown in FIG. 10(b), in the case of a positive angle, the characteristic part 40 not only moves to the right as the angle increases, but also the characteristic part 40 is shaped like a parallelogram with the lower side closer to the right. May be shown in the form.

DESCRIPTION OF SYMBOLS 1... Marker, 4, 4A, 4B... Position recognition part, 20... First layer, 21... Allowance part, 22... Blocking part, 23... Slit, 30... - Second layer, 31... Retroreflective member, 61... Scattering part, 62... Transmissive part.

Claims (5)

A marker having a position recognition part in which visual information observed changes depending on the direction of observation,
The position recognition unit is
A first layer configured by a pattern of a permitting portion that allows light to pass through and a blocking portion that blocks light;
a second layer provided on the back side of the first layer and having a member that can be visually recognized through the allowing portion ;
The blocking portion of the first layer is constituted by a pattern of scattering portions that scatter light formed on the front and back surfaces of the base material,
The permissible portion of the first layer is a marker configured by a pattern of a transparent portion of the front surface and the back surface of the base material, on which the scattering portion is not formed . 2. The marker according to claim 1, wherein the allowing portion is configured to increase an inclination angle with respect to the thickness direction of the light that is allowed to pass outward as the distance from the central position of the position recognition portion increases. A marker having a position recognition part in which visual information observed changes depending on the direction of observation,
The position recognition unit is
A first layer configured by a pattern of a permitting portion that allows light to pass through and a blocking portion that blocks light;
a second layer provided on the back side of the first layer and having a member that can be visually recognized through the allowing portion;
The allowing portion of the first layer is formed by a slit formed between the pair of blocking portions,
The marker is configured such that the allowing portion increases outwardly an inclination angle with respect to a thickness direction of light that is allowed to pass as the distance from the central position of the position recognizing portion increases outwardly. The marker according to any one of claims 1 to 3 , wherein the second layer member is a reflective member that reflects light. The marker according to claim 4 , wherein the reflective member is a retroreflective member.

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