Marker and lidar system

Abstract

Provided is a marker (10) that can be detected by a plurality of LiDAR devices (20), the marker (10) comprising: a pole part (11); and a reflection part (12) that is provided at one end of the pole part (11) and that has a plurality of reflection regions which have different reflectivities and which reflect, toward the LiDAR devices (20), light emitted from the LiDAR devices (20).

Description

Marker and LiDAR system

[0001] The present invention relates to a marker and a LiDAR system.

[0002] Light Detection and Ranging (LiDAR) devices for detecting objects are known. In this case, Patent Document 1 below discloses a LiDAR system that uses two LiDAR devices to detect objects. In this LiDAR system, the detection areas of the LiDAR devices partially overlap, and markers located in this overlapping area are detected. Specifically, this LiDAR system integrates point cloud data based on the coordinates of the markers measured by each LiDAR device. This can suppress a decrease in object detection accuracy compared to when the markers are not used. Examples of such markers include tiles.

[0003] JP 2023-118608 A

[0004] As in the LiDAR system described above, when an area that reflects laser light from the LiDAR device is placed along the ground or floor, an obstacle may prevent the laser light from reaching that area, making it difficult to detect the marker.

[0005] Therefore, an object of the present invention is to provide a marker that is easily detected by a LiDAR device and a LiDAR system.

[0006] In order to achieve the above-mentioned object, the present invention provides a marker that can be detected by multiple LiDAR devices, characterized by comprising a pole portion and a reflective portion provided at one end of the pole portion and having multiple reflective areas with different reflectivities that reflect light emitted from the LiDAR device toward the LiDAR device.

[0007] The present invention also provides a LiDAR system comprising at least two LiDAR devices whose detection areas partially overlap each other, a marker placed in an overlapping area where the detection areas of each LiDAR device overlap each other, and a processor that integrates the point cloud data output from each of the LiDAR devices based on multiple point data indicating the marker, wherein the marker has a pole portion and a reflecting portion provided at one end of the pole portion and having multiple reflective areas with different reflectivities that reflect light emitted from the LiDAR device toward the LiDAR device, and the multiple point data are data based on light reflected by at least two reflective areas.

[0008] As described above, the marker has a pole portion and a reflecting portion provided at one end of the pole portion. By installing the marker with the pole portion upright, irradiation of laser light from the LiDAR device onto multiple reflecting areas can be prevented from being obstructed by obstacles placed on the ground or floor, compared to when the reflecting areas are placed along the ground or floor. Therefore, the marker of the present invention is easily detected by a LiDAR device. Furthermore, because the reflecting portion has multiple reflecting areas with different reflectivities, light reflected from the reflecting areas with different reflectivities enters the LiDAR device as light of different intensities. Therefore, the LiDAR device can generate data related to the position and orientation of the marker based on the intensity distribution of the incident light. By creating data related to a common marker among multiple LiDAR devices, point cloud data output by each of the multiple LiDAR devices can be integrated based on this data. In other words, the marker of the present invention can serve as a reference marker when integrating point cloud data from multiple LiDAR devices.

[0009] The reflective portion preferably includes at least three types of reflective regions having different reflectances.

[0010] In this case, the reflector can have a more diverse reflectivity distribution than a reflector having two reflective regions with the above-mentioned reflectivities, and the LiDAR device can generate more accurate data regarding the orientation of the marker.

[0011] It is preferable that the size of the reflecting portion along the radial direction of the pole portion is larger than the size of the pole portion along the radial direction.

[0012] In this case, the reflecting portion can be made larger than the area of ​​the ground on which the pole is installed, so the LiDAR device can generate a larger number of point data representing the marker. Therefore, even if the installation area of ​​the marker is small, accurate data relating to the marker can be generated.

[0013] The distribution of the reflective areas of the reflective portion is preferably rotationally asymmetric.

[0014] In this case, regardless of the orientation of the LiDAR device relative to the marker, the intensity distribution of the light reflected by the reflector is unique, and the relative positional relationship between the marker and the LiDAR device is uniquely determined. This reduces the load on the processor that integrates the point cloud data.

[0015] It is preferable that the reflecting portion has a shape having a plurality of planar side surfaces that are not parallel to the radial direction of the pole portion, and that adjacent side surfaces are reflecting regions having different reflectances.

[0016] The flat reflective area reduces variations in reflectivity within the reflective area, and adjacent reflective areas have different orientations, making it easier for the LiDAR device to identify the position of each reflective area on the side, thereby generating more accurate marker data.

[0017] The planar side surface may extend in the radial direction.

[0018] In this case, the pole is erected so that the plane of the side surface is horizontal. In this case, when the distance between the LiDAR device and the marker is large, the angle of incidence of the laser light from the LiDAR device with respect to the side surface can be reduced. This increases the reflectivity of the laser light, enabling more accurate marker data to be generated.

[0019] It is also preferable that the surface direction of the planar side surface is oriented in a direction from the other end of the pole portion toward the one end rather than in the radial direction.

[0020] In this case, by erecting the pole portion, the surface direction of the planar side surface faces upward from the horizontal. The LiDAR device may be installed at a high position. For example, LiDAR devices used in infrastructure facilities in towns and the like are generally installed at a high position. By facing the surface direction of the side surface upward from the horizontal as described above, the side surface can be directed toward the LiDAR. This can increase the reflectivity of the laser light from the LiDAR device.

[0021] The number of planar sides may be six.

[0022] If the number of planes is six, light reflected from three side surfaces can be incident on the LiDAR device, making it easier for the LiDAR device to identify the positions of the three side surfaces and generating more accurate marker data than if the number of planes were less than six.

[0023] The surface of the reflecting portion opposite to the pole portion side may be flat, and the plurality of reflecting regions may be provided on the flat surface.

[0024] In this case, by erecting the pole portion, the planar surface on which the multiple reflective areas are provided becomes the upper surface of the reflective portion. As described above, the LiDAR device may be installed at a high position. Therefore, by providing the reflective area on the upper surface, it may be easier for the laser light from the LiDAR device to be irradiated.

[0025] As described above, according to the present invention, a marker that is easily detected by a LiDAR device and a LiDAR system can be provided.

[0026] Fig. 1 is a schematic diagram of an object detection system according to an embodiment of the present invention. Fig. 2 is a schematic diagram of a marker. Fig. 3 is a diagram of a first modified example of the marker seen from above. Fig. 4 is a diagram of a second modified example of the marker seen from above. Fig. 5 is a schematic diagram of a LiDAR device. Fig. 6 is a flowchart showing the operation of the processor 30. Fig. 7 is a schematic diagram showing a third modified example of the marker.

[0027] Preferred embodiments of a marker and LiDAR system according to the present invention will be described in detail below with reference to the drawings. The embodiments exemplified below are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention can be modified and improved within the scope of the claims. The present invention may also be achieved by appropriately combining the components in the embodiments exemplified below. Note that in the drawings referred to below, the dimensions of each component may be changed to facilitate understanding. Also, in the drawings, for ease of viewing, similar components may be assigned reference symbols only in some cases, and some reference symbols may be omitted.

[0028] 1 is a schematic diagram of a LiDAR system according to the present embodiment. The LiDAR system 1 according to the present embodiment mainly includes a marker 10, a plurality of LiDAR devices 20, and a processor 30.

[0029] Each LiDAR device 20 is individually installed, for example, on a support post near a road. Furthermore, each LiDAR device 20 is installed in a different position and orientation, with a portion of each detection area AR overlapping with the other. The LiDAR device 20 detects an object located within the detection area AR by emitting laser light into the detection area AR and detecting the light reflected from the laser light. In FIG. 1 , the area where the detection areas AR of each LiDAR device 20 overlap is shown as an overlap area OL. A marker 10 is installed in the overlap area OL.

[0030] Fig. 2 is a conceptual diagram of the marker 10. As shown in Fig. 2, the marker 10 has a pole portion 11 and a reflecting portion 12 as its main components.

[0031] The pole portion 11 has a columnar shape and is installed, for example, with its longitudinal direction aligned vertically. The pole portion 11 has, for example, a diameter of 10 cm to 20 cm and a length of 1 m to 2 m. The cross-sectional shape perpendicular to the longitudinal direction is, for example, circular or rectangular. A reflecting portion 12 is provided at one end of the pole portion 11. Although not specifically shown, the pole portion 11 may have, for example, a sharp end on the side opposite the reflecting portion 12, which is pierced into the ground surface and installed on the ground surface, or may have legs at the other end that extend outward from the pole portion 11 and be installed on the ground surface.

[0032] As described above, in this embodiment, the reflecting section 12 provided at one end of the pole section 11 has a generally hexagonal prism shape. In this example, the reflecting section 12 has a rotationally symmetric shape, specifically, a rotationally symmetric shape with respect to the central axis C of the pole section 11. Therefore, each side surface 120 of the reflecting section 12 is planar, and the top surface 130, which is the surface opposite to the pole section 11, is also planar. To avoid complicating the illustration, only one side surface 120 is shown in FIG. 2. The reflecting section 12 is provided at one end of the pole section 11 so that the surface direction of each side surface 120 is perpendicular to the longitudinal direction of the pole section 11. Therefore, the side surfaces 120 of the reflecting section 12 in this embodiment are not parallel to the radial direction of the pole section 11. Therefore, a line passing through the side surface 120 and extending along the surface direction of the side surface 120 can intersect with the pole section 11. As described above, when the pole section 11 is installed so that the longitudinal direction is the up-down direction, the surface direction of the side surface 120 is horizontal. Because the surface direction of the side surface 120 is horizontal, when the distance between the LiDAR device 20 and the marker 10 is large, the angle of incidence of the laser light emitted from the LiDAR device 20 on the side surface 120 can be reduced, as described below. Furthermore, the radial size of the pole portion 11 in the reflecting unit 12 is larger than the size of the pole portion 11 in that direction. Therefore, when the pole portion 11 is installed so that its longitudinal direction is the up-down direction, the horizontal size of the reflecting unit 12 is larger than the horizontal size of the pole portion 11. Therefore, since the reflecting unit 12 can be larger than the area of ​​the ground or the like on which the pole portion 11 is installed, when the LiDAR device 20 generates multiple point data indicating a marker, the number of point data can be increased.

[0033] The reflecting unit 12 has a plurality of side reflective regions 121-126 and top reflective regions 131-136 with different reflectivities that reflect light emitted from the LiDAR device 20 toward the LiDAR device. The side reflective regions 121-126 are provided in the order of side reflective regions 121-126 on each side surface 120 of the hexagonal prism. The top reflective regions 131-136 are provided on the top surface 130 of the hexagonal prism. In this embodiment, the top surface 130 is divided into regions by straight lines drawn from the center of the top surface 130 to each vertex of the top surface 130, and the top reflective regions 131-136 are provided in the order of top reflective regions 131-136 in each region. The side reflective region 121 and the top reflective region 131 are adjacent to each other via the edges of the side surface 120 and the top surface 130. Similarly, side reflective area 122 and top reflective area 132, side reflective area 123 and top reflective area 133, side reflective area 124 and top reflective area 134, side reflective area 125 and top reflective area 135, and side reflective area 126 and top reflective area 136 are adjacent to each other via the edges of side surface 120 and top surface 130, respectively. Therefore, the distribution of reflective areas in reflective section 12 is rotationally symmetric.

[0034] In this embodiment, the reflectance of each reflective area of ​​the installed marker 10 that reflects light emitted from the LiDAR device 20 toward the LiDAR device is classified into three different types: first reflectance, second reflectance, and third reflectance. For example, the side reflective areas 121, 124 and the top reflective areas 131, 134 have a first reflectance, the side reflective areas 122, 125 and the top reflective areas 132, 135 have a second reflectance, and the side reflective areas 123, 126 and the top reflective areas 133, 136 have a third reflectance. In this case, the reflectance distribution of the reflector 12 is rotationally symmetric about 180 degrees. In this example, the reflectance distribution of the reflector 12 is rotationally symmetric with respect to the central axis C of the pole portion 11.

[0035] Furthermore, for example, similar to the above, the side reflective areas 121 and 124 and the top reflective areas 131 and 134 have a first reflectance, while, slightly different from the above, the side reflective areas 122 and 126 and the top reflective areas 132 and 136 have a second reflectance, and slightly different from the above, the side reflective areas 123 and 125 and the top reflective areas 133 and 135 have a third reflectance. In this case, the reflective area distribution of the reflective unit 12 is rotationally symmetric, but the reflectance distribution is not rotationally symmetric. Furthermore, the reflectance of the side reflective area and the top reflective area adjacent to each other across the edge of the side surface 120 and the top surface 130, such as the side reflective area 121 and the top reflective area 131, may be different from each other. As in these examples, by having the reflective portion 12 include at least three types of reflective regions with different reflectivities, a more diverse reflectivity distribution can be achieved compared to when the reflective portion 12 is composed of reflective regions with two types of reflectivities, and when the LiDAR device 20 generates data regarding the orientation of the marker 10 as described below, more accurate data regarding the orientation can be generated.

[0036] FIG. 3 is a top view of a first modified example of the marker 10. As shown in FIG. 3, in this modified example, the distribution of the upper surface reflective regions 131-136 on the upper surface 130 of the reflector 12 is rotationally asymmetric. In this example, the shape of each of the upper surface reflective regions 131-136 is rotationally asymmetric. Because the distribution of the reflective regions of the reflector 12 is rotationally asymmetric in this manner, regardless of the orientation of the LiDAR device 20 relative to the marker 10, the intensity distribution of light reflected by the reflector 12 is unique, and the relative positional relationship between the marker 10 and the LiDAR device 20 can be uniquely determined. Note that in this example, the outer shape of the reflector 12 is rotationally symmetric, specifically, rotationally symmetric with respect to the central axis C.

[0037] FIG. 4 is a top view of a second modified example of the marker 10. As shown in FIG. 4, in this modified example, the outer shape of the reflector 12 is non-rotationally symmetric. Because the outer shape of the reflector 12 is non-rotationally symmetric, the distribution of the upper surface reflection regions 131-136 on the upper surface 130 is also non-rotationally symmetric. Because the outer shape of the reflector 12 is non-rotationally symmetric, the intensity distribution of the light reflected by the reflector 12 is unique regardless of the orientation of the LiDAR device 20 relative to the marker 10, and the relative positional relationship between the marker 10 and the LiDAR device 20 can be uniquely determined.

[0038] In reflective regions having different reflectivities that reflect light emitted from the LiDAR device 20 toward the LiDAR device 20, differences in reflectivity may be achieved by using different surface materials or different surface roughnesses. Also, differences in reflectivity may be achieved by making the surfaces of some reflective regions retroreflective. When using different surface materials for the reflective regions, for example, the reflective regions may be divided into a reflective region whose surface is coated with a paint containing carbon pigment, a reflective region whose surface is coated with a paint containing titanium oxide pigment, and a reflective region whose surface is coated with an aluminum pigment. Even if the same pigment is used, the reflectivity may be varied depending on the particle size. When using different surface roughness, for example, the reflective region may be divided into a reflective region with a very smooth surface and a reflective region whose surface is roughened by sandblasting or the like. When using a retroreflective structure, a bead-type retroreflective structure or a pyramidal retroreflective structure may be used.

[0039] The laser light emitted from each LiDAR device 20 is reflected by at least two reflective regions of the marker 10, each having a different reflectivity. That is, the marker 10 is sized to be able to reflect the laser light in this manner. Furthermore, when laser light is irradiated from the LiDAR device 20, it is preferable that the marker 10 is sized so that the laser light is irradiated to multiple locations in each of the reflective regions irradiated with the laser light.

[0040] Next, the LiDAR device 20 will be described.

[0041] FIG. 5 is a schematic diagram of a LiDAR device 20. The LiDAR devices 20 shown in FIG. 1 of this embodiment have the same configuration. As described above, the LiDAR device 20 uses laser light to detect objects located within the detection area AR. Examples of objects include fixed objects such as road surfaces and buildings, and moving objects such as vehicles and people. Through this detection, the LiDAR device 20 can detect, for example, the gradient of a road surface or the shape of a building, or the movement of vehicles, people, etc. The LiDAR device 20 of this embodiment may be, for example, a raster scan LiDAR device. The LiDAR device 20 primarily comprises a cover 29, a driver circuit 21, a laser light source 22, an H-direction scanning drive mirror 23, a V-direction scanning drive mirror 24, a light receiving element 25, and a point cloud data generator 26, all of which are housed within the cover 29. In the example of Figure 2, the LiDAR device 20 is a mechanical LiDAR device, but it may also be a phased array LiDAR device that does not include a driving unit (not shown) described later.

[0042] The cover 29 has a storage space for housing the driver circuit 21, the laser light source 22, the driving mirror 23 for H-direction scanning, the driving mirror 24 for V-direction scanning, the light receiving element 25, and the point cloud data generation unit 26, and transmits the laser light Lb emitted from the laser light source 22 and the reflected light Lr that is reflected by an object within the detection area AR.

[0043] The driver circuit 21 is composed of, for example, a plurality of logic circuits, and is electrically connected to the laser light source 22, the H-direction scanning drive mirror 23, and the V-direction scanning drive mirror 24 to control them.

[0044] The laser light source 22 emits laser light Lb of a predetermined wavelength. This laser light Lb is near-infrared light with a wavelength of, for example, 905 nm or 1550 nm. The timing at which the laser light source 22 emits the laser light Lb is controlled by the driver circuit 21, and the laser light source 22 emits the laser light Lb in response to a signal from the driver circuit 21. The driver circuit 21 is electrically connected to the point cloud data generator 26, and outputs data including the timing at which the laser light is emitted from the laser light source 22 to the point cloud data generator 26.

[0045] The H-direction scanning drive mirror 23 has a mirror that reflects the laser light Lb emitted from the laser light source 22 and a drive unit (not shown) that is controlled by the driver circuit 21. When reflecting the laser light Lb, the H-direction scanning drive mirror 23 reflects the laser light Lb while changing the reflection angle in the horizontal direction by the drive unit. By changing the reflection angle of the H-direction scanning drive mirror 23, the LiDAR device 20 performs horizontal scanning.

[0046] The V-direction scanning drive mirror 24 includes a mirror that reflects the laser light Lb reflected by the H-direction scanning drive mirror 23 and a drive unit (not shown) that is controlled by the driver circuit 21. When reflecting the laser light Lb, the V-direction scanning drive mirror 24 reflects the laser light Lb while changing the reflection angle in the vertical direction using the drive unit. This change in the reflection angle of the V-direction scanning drive mirror 24 changes the horizontal scanning position performed by the LiDAR device 20 in the vertical direction. The laser light reflected by the V-direction scanning drive mirror 24 passes through the cover 29 and is irradiated ahead of the vehicle.

[0047] The H-direction scanning drive mirror 23 and the V-direction scanning drive mirror 24 are configured to include, for example, a polygon mirror or a galvanometer mirror. The H-direction scanning drive mirror 23 and the V-direction scanning drive mirror 24 may each be configured with a MEMS mirror. The H-direction scanning drive mirror 23 and the V-direction scanning drive mirror 24 may be combined into two mirrors with biaxial scanning, and the order in which the laser light Lb is reflected by the H-direction scanning drive mirror 23 and the V-direction scanning drive mirror 24 may be reversed.

[0048] The light receiving element 25 is an element that receives reflected light Lr, which is laser light Lb reflected by an object within the detection area AR. The reflected light Lr received by the light receiving element 25 contains information related to the object located within the detection area AR. The light receiving element 25 outputs a signal that changes depending on the intensity of the received light. The light receiving element 25 is electrically connected to the point cloud data generation unit 26, and the information is input to the point cloud data generation unit 26 as an electrical signal.

[0049] The point cloud data generator 26 generates point data for each reflection position based on the direction of the reflection position where the laser beam Lb is reflected, the distance to the reflection position, and the intensity of the light received by the light receiving element 25, based on data related to the emission timing of the laser beam Lb input from the driver circuit 21, information input from the light receiving element 25, and timing data of the information input from the light receiving element 25. The point data includes information related to the coordinates of the point and the intensity of the light reflected at the position that becomes the point data. Therefore, the point cloud data generator 26 generates point cloud data, which is a collection of point data. The point cloud data generator 26 is electrically connected to the processor 30, and the point cloud data is input to the processor 30.

[0050] As described above, since the marker 10 is placed in the overlap region OL, the marker 10 is detected by each LiDAR device 20. Therefore, the point cloud data output from each LiDAR device 20 includes point cloud data indicating the coordinates of the marker 10.

[0051] The processor 30 may be, for example, a microcontroller, an integrated circuit such as an IC (Integrated Circuit), an LSI (Large-scale Integrated Circuit), or an ASIC (Application Specific Integrated Circuit), or a numerical control (NC) device. The processor 30 may use a machine learning device or may not use a machine learning device. The processor 30 controls the integration of point cloud data output from each LiDAR device 20 and the operation of the LiDAR device 20. The processor 30 includes a control unit 31, a calculation unit 32, an integration unit 33, and an output unit 34. The control unit 31, the calculation unit 32, the integration unit 33, and the output unit 34 are electrically connected via a bus line. The processor 30 is also electrically connected to a memory 40.

[0052] The memory 40 is configured to store data related to the refractive index distribution of the marker 10 and to be able to read the data. The memory 40 is, for example, a non-transitory recording medium, and is preferably a semiconductor recording medium such as a random access memory (RAM) or a read only memory (ROM), but may include any type of recording medium, such as an optical recording medium or a magnetic recording medium. Note that the term "non-transitory" recording medium includes all computer-readable recording media except for transient, propagating signals, and does not exclude volatile recording media. Note that the memory 40 may be provided in a single package together with the processor 30.

[0053] The control unit 31 controls each LiDAR device 20. For example, the control unit 31 controls the timing at which each LiDAR device 20 detects an object in the detection area AR. At this time, the control unit 31 may instruct the driver circuit 21 on the timing at which the LiDAR device 20 detects one frame of the detection area AR. In this case, the driver circuit 21 instructs the emission of laser light Lb so as to start detection for one frame at the timing received from the control unit 31. The control unit 31 also controls the operation of the calculation unit 32, the integration unit 33, and the output unit 34.

[0054] The calculation unit 32 calculates the position and orientation of the marker 10 in the point cloud data output from each LiDAR device 20. The calculation unit 32 compares information related to the reflectance distribution of the marker 10 stored in the memory 40 with information related to the intensity distribution of the reflected light Lr based on information related to the intensity of the reflected light Lr of each point data in each point cloud data. As described above, the marker 10 is sized so that the laser light Lb emitted from each LiDAR device 20 is reflected by at least two reflection regions with different reflectivities. Therefore, the multiple point data are data based on light reflected by at least two reflection regions. This comparison identifies the coordinates of the marker 10 in each point cloud data. The calculation unit 32 also identifies the orientation of the marker 10. When this orientation is set to a predetermined direction, the predetermined direction is, for example, a predetermined direction. For example, if the predetermined direction is the direction from upper surface reflection region 132 to upper surface reflection region 135 along the in-plane direction of the upper surface 130 of marker 10, the calculation unit 32 identifies the position of marker 10 in each piece of point cloud data as described above, and identifies the predetermined direction of the marker 10. The position of marker 10 is identified, for example, by x, y, and z coordinates in each piece of point cloud data. Furthermore, the predetermined direction is identified, for example, by the roll angle, pitch angle, and yaw angle relative to the x, y, and z coordinates in each piece of point cloud data.

[0055] In addition, if the refractive index distribution of the marker 10 is rotationally symmetric, the most appropriate orientation is selected so that the orientations of the marker 10 in the point cloud data output from each LiDAR device 20 are not the same. This selection may be made using machine learning or based on a predetermined algorithm. For example, as shown in FIG. 1, assume that two LiDAR devices 20 are located on opposite sides of the marker 10 and the reflectance distribution of the marker 10 is rotationally symmetric by 180 degrees. In this case, if the predetermined direction of the marker 10 in the point cloud data of one LiDAR device 20 coincides with the x-axis direction, the other LiDAR device 20 selects the -x-axis direction from the x-axis direction and the -x-axis direction so that its position does not overlap with the position of the other LiDAR device 20. The data calculated by the calculation unit 32 is output to the integration unit 33.

[0056] The integrating unit 33 integrates the point cloud data output from each LiDAR device 20 using multiple point data indicating the marker 10 as a reference. At this time, the point cloud data is integrated so that the positions and orientations of the markers 10 from each LiDAR device 20 match each other in the coordinate system of the integrated data. In other words, in the integrated data, the point cloud data output from each LiDAR device 20 is represented in a single coordinate system. The data integrated by the integrating unit 33 is output to the output unit 34.

[0057] The output unit 34 is a component that outputs the integrated point cloud data from the processor 30. The output unit 34 outputs the integrated point cloud data to a monitor 50, for example.

[0058] The monitor 50 displays the integrated point cloud data output from the output unit 34. Note that the monitor 50 is not an essential component of the LiDAR system 1.

[0059] Next, the operation of the processor 30 of this embodiment will be described.

[0060] 6 is a flowchart showing the operation of the processor 30. As shown in FIG. 6, the operation of the processor 30 includes steps S1 to S4.

[0061] (Step S1) This step is a point cloud data acquisition step for acquiring point cloud data from each LiDAR device 20. In this step, the control unit 31 of the processor 30 outputs a trigger signal to the driver circuit 21 of each LiDAR device 20. Upon receiving this signal, the driver circuit 21 operates the laser light source 22, the H-direction scanning drive mirror 23, and the V-direction scanning drive mirror 24 to perform detection for one frame. At this time, the driver circuit 21 drives the H-direction scanning drive mirror 23 to slightly tilt each time the laser light source 22 emits laser light, and operates the V-direction scanning drive mirror 24 to slightly tilt each time the laser light source 22 emits laser light a predetermined number of times, and operates the H-direction scanning drive mirror 23 to return its tilt to the state it was in before the laser light source 22 emitted laser light a predetermined number of times. The light receiving element 25 outputs a signal corresponding to the intensity of the received reflected light Lr, and the point cloud data generator 26 generates data related to the coordinates of each point constituting the point cloud data and the intensity of the reflected light Lr based on this signal and a signal from the driver circuit 21. This point data is collected to generate point cloud data. The generated point cloud data is output to the processor 30. The processor 30 thus acquires point cloud data from each LiDAR device 20. It is preferable that the emission timings of the laser beams from each LiDAR device 20 do not overlap with each other so that the reflected light Lr of the laser beam Lb emitted from one LiDAR device 20 is not used to generate point cloud data for the other LiDAR device 20. For example, it is preferable that each LiDAR device 20 be controlled to alternately generate one frame of point cloud data. Furthermore, Since the wavelengths of the laser light Lb of each LiDAR device 20 are different from each other, the LiDAR device 20 may receive and process the reflected light Lr of the laser light Lb emitted by itself, and may not process the reflected light Lr of the laser light Lb emitted by other LiDAR devices 20.

[0062] (Step S2) This step is a calculation step in which the position and orientation of the marker 10 are calculated from each point cloud data. In this step, each point cloud data input in step S1 is input to the calculation unit 32. The calculation unit 32 reads data related to the reflectance distribution of the marker 10 from the memory 40. Then, as described above, the calculation unit 32 compares the information related to the reflectance distribution of the marker 10 with the information on the intensity distribution of the reflected light Lr in each point cloud data, and identifies the coordinates and orientation of the marker 10 in each point cloud data. The information related to the identified coordinates and orientation of the marker 10 in each point cloud data is output to the integration unit 33.

[0063] (Step S3) This step is a point cloud data integration step in which each point cloud data is integrated into a common coordinate system based on the coordinates and orientation of the marker 10. In this step, the integration unit 33 integrates each point cloud data from each LiDAR device 20 into a single coordinate system based on information from the calculation unit 32 so that the positions and orientations of the markers 10 included in the point cloud data from each LiDAR device 20 match in the integrated data. In this way, the point cloud data output by each LiDAR device 20 is integrated. The integrated point cloud data is output to the output unit 34.

[0064] (Step S4) This step is an output step for outputting the integrated point cloud data. The output unit 34 outputs the point cloud data integrated by the integration unit 33. The output point cloud data is displayed on the monitor 50. The output point cloud data may also be output to a processing unit other than the monitor 50. The processing unit other than the monitor 50 performs predetermined processing based on the point cloud data. After this step, the processor 30 ends this flowchart. The processor 30 may return the flowchart to step S1.

[0065] As described above, the marker 10 of this embodiment is a marker that can be detected by multiple LiDAR devices 20, and includes a pole portion 11 and a reflecting portion 12 that is provided at one end of the pole portion 11 and has multiple reflective regions with different reflectivities that reflect light emitted from the LiDAR device 20 toward the LiDAR device 20. In this embodiment, the multiple reflective regions are side reflective regions 121 to 126 and top reflective regions 131 to 136.

[0066] In addition, the LiDAR system 1 of this embodiment comprises at least two LiDAR devices 20 whose detection areas AR partially overlap each other, a marker 10 placed in an overlap area OL where the detection areas AR overlap each other, and a processor 30 that integrates the point cloud data output from each LiDAR device 20 based on multiple point data indicating the marker 10, and the marker 10 has a pole portion 11 and a reflecting portion 12 provided at one end of the pole portion 11 and having multiple reflective areas with different reflectivities that reflect light emitted from the LiDAR device 20 toward the LiDAR device 20, and the multiple point data is data based on light reflected by at least two reflective areas.

[0067] Because the marker 10 has a pole portion 11 and the reflecting portion 12 is provided at one end of the pole portion 11, installing the marker 10 with the pole portion 11 standing upright can prevent the irradiation of laser light from the LiDAR device 20 to multiple reflecting areas from being obstructed by obstacles placed on the ground or floor, compared to when the reflecting areas are placed along the ground or floor. Therefore, the marker 10 of this embodiment is easily detected by the LiDAR device 20. Furthermore, because the reflecting portion 12 has multiple reflecting areas with different reflectivities, light reflected from the reflecting areas with different reflectivities enters the LiDAR device 20 as light with different intensities. Therefore, the LiDAR device 20 can generate data related to the position and orientation of the marker 10 based on the intensity distribution of the incident light. By each LiDAR device 20 creating data related to a common marker, the point cloud data output by each LiDAR device 20 can be integrated based on this data. In other words, the marker 10 of this embodiment can serve as a reference marker when integrating point cloud data from multiple LiDAR devices 20.

[0068] Although the present invention has been described above using the above-mentioned embodiments as examples, the present invention is not limited to these.

[0069] For example, the shape and reflectivity distribution of the marker 10 are not limited to those of the above-described embodiment. FIG. 7 is a schematic diagram illustrating a third modified example of the marker 10. The marker 10 illustrated in FIG. 7 differs from the above-described embodiment in that the surface direction of each side surface 120 of the reflecting portion 12 faces upward relative to the horizontal. Therefore, the surface direction of each side surface reflective region 121-126 faces upward relative to the horizontal. Therefore, the side surface 120 of the reflecting portion 12 in this example is non-parallel to the radial direction of the pole portion 11. LiDAR devices 20 used in infrastructure facilities, such as those in urban areas, are generally installed at high positions. By facing the surface direction of the side surface 120 upward relative to the horizontal, as in this modified example, the side surface 120 can be directed toward the LiDAR device 20. This can increase the reflectivity of the laser light Lb from the LiDAR device 20, making it easier to extract multiple point data representing the marker 10 from point cloud data.

[0070] In the LiDAR system 1, it is preferable that at least two LiDAR devices 20 are installed so that the laser light Lb emitted from each LiDAR device 20 is irradiated onto at least two common side reflection regions. For example, one LiDAR device 20 is installed at a position where the laser light Lb is irradiated onto successively adjacent side reflection regions 121 to 123, and the other LiDAR device 20 is installed at a position where the laser light Lb is irradiated onto successively adjacent side reflection regions 122 to 124. In this case, the positions where the LiDAR devices 20 are installed are different from the positions where the pair of LiDAR devices 20 in FIG. 1 are installed.

[0071] In the above embodiment, the side reflective areas 121 to 126 and the top reflective areas 131 to 136 are each classified into three types of reflective areas. However, the side reflective areas 121 to 126 and the top reflective areas 131 to 136 may be classified into two types of reflective areas having the above reflectance, or may be classified into four or more types of reflective areas.

[0072] Furthermore, although the marker 10 has side reflective regions 121-126 and top reflective regions 131-136, it is not necessary for the marker 10 to have one of the side reflective regions 121-126 and the top reflective regions 131-136, as long as the reflective portion 12 of the marker 10 is represented by a plurality of point cloud data by the LiDAR device 20. However, when a plurality of reflective regions are provided on the planar top surface 130, it is preferable to provide a plurality of reflective regions on the top surface 130 so that the light from the LiDAR device 20 can be received evenly.

[0073] In the above embodiment, the size of the reflecting part 12 along the radial direction of the pole part 11 is larger than the size of the pole part 11 along the radial direction. However, the size of the reflecting part 12 along the radial direction of the pole part 11 may be equal to or smaller than the size of the pole part 11 along the radial direction. For example, one end face of the pole part 11 may be the reflecting part 12.

[0074] Furthermore, in the above embodiment, an example was described in which the reflecting portion 12 is shaped like a hexagonal prism, but the number of planar side surfaces 120 may be 3 to 5, or may be 8 or more. However, in order to prevent the size of the side surfaces 120 from becoming too small, the number of side surfaces 120 is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. Furthermore, in order to allow the LiDAR device 20 to detect many side surfaces 120, the number of side surfaces is preferably 5 or more, more preferably 6 or more. Therefore, the number of side surfaces is most preferably 6.

[0075] In addition, the memory 40 may store multiple relationships between the orientation of the marker 10 and the intensity distribution of the reflected light in advance, and in step S2, the calculation unit 32 may compare the multiple light intensity distributions with the light intensity distribution in the point cloud data acquired in step S1, and calculate the orientation of the marker 10 corresponding to the intensity distribution in the memory 40 that is closest to the light intensity distribution acquired in step S1 as the orientation of the marker 10.

[0076] According to the present invention, a marker that is easily detected by a LiDAR device and a LiDAR system can be provided, and can be used in the field of object monitoring.

Claims

1. A marker that can be detected by multiple LiDAR devices, comprising: a pole portion; and a reflective portion provided at one end of the pole portion and having multiple reflective areas with different reflectivities that reflect light emitted from the LiDAR device toward the LiDAR device.

2. The marker according to claim 1, characterized in that the reflective portion includes at least three types of reflective regions each having a different reflectance.

3. The marker according to claim 1, characterized in that the size of the reflecting portion along the radial direction of the pole portion is greater than the size of the pole portion along the radial direction.

4. The marker according to claim 1, characterized in that the distribution of the reflective areas of the reflective portion is rotationally asymmetric.

5. The marker described in claim 1, characterized in that the reflective portion has a shape having multiple planar side surfaces that are not parallel to the radial direction of the pole portion, and adjacent side surfaces are reflective areas having different reflectivities.

6. The marker according to claim 5, characterized in that the surface direction of the flat side surface is aligned with the radial direction.

7. The marker according to claim 5, characterized in that the surface direction of the flat side surface faces in a direction from the other end of the pole portion toward the one end rather than in the radial direction.

8. The marker according to claim 5, characterized in that the number of said planar sides is six.

9. A marker as described in claim 1, characterized in that the surface of the reflecting portion opposite the pole portion is flat, and the multiple reflecting areas are provided on the flat surface.

10. A LiDAR system comprising: at least two LiDAR devices whose detection areas partially overlap each other; a marker placed in an overlapping area where each of the detection areas overlap; and a processor that integrates the point cloud data output from each of the LiDAR devices using multiple point data indicating the marker as a reference; wherein the marker has a pole portion and a reflective portion provided at one end of the pole portion and having multiple reflective areas with different reflectivities that reflect light emitted from the LiDAR device toward the LiDAR device; and the multiple point data is data based on light reflected by at least two of the reflective areas.

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