Sensor device

Abstract

Control the density distribution of multiple spots to an appropriate distribution. [Solution] The control unit 200 determines whether the multiple spots irradiated by the scanning unit 100 satisfy predetermined conditions. The control unit 200 controls the density distribution of the multiple spots irradiated by the scanning unit 100 until the multiple spots irradiated by the scanning unit 100 satisfy predetermined conditions.

Description

[Technical Field]

[0001] The present invention relates to a sensor device. [Background Art]

[0002] In recent years, various sensor devices such as LiDAR (Light Detection And Ranging) have been developed. A sensor device includes a scanning unit such as a MEMS (Micro Electro Mechanical Systems) mirror. The scanning unit reflects a plurality of beams repeatedly emitted from a light source such as a pulsed laser, and irradiates a plurality of spots within a field of view (FOV). The sensor device detects reflected beams from the plurality of spots by using a photodetector such as an APD (avalanche photodiode). The sensor device generates a point cloud using detection results from the photodetector, and detects, recognizes, or identifies an object irradiated with the plurality of spots.

[0003] Patent Document 1 describes an example of a sensor device. The sensor device includes a first LiDAR and a second LiDAR. The first LiDAR irradiates a plurality of beams spatially uniformly within the FOV. The second LiDAR irradiates a plurality of beams spatially non-uniformly within the FOV. [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] Japanese National Publication of International Patent Application No. 2019-526056 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] By controlling the density distribution of multiple spots illuminating an object and increasing the density of those spots, it may be possible to detect, recognize, or identify the object with relatively high resolution. However, simply increasing the density of multiple spots can result in an unsuitable density distribution, such as a smaller field of view (FOV), which may narrow the detection range of the object unnecessarily, or an unnecessarily high density of the multiple spots.

[0006] One example of a problem that this invention aims to solve is controlling the density distribution of multiple spots to an appropriate distribution. [Means for solving the problem]

[0007] The invention described in claim 1 is, Scanning unit and, A control unit controls the density distribution of the plurality of spots irradiated by the scanning unit until the plurality of spots irradiated by the scanning unit satisfy a first predetermined condition, This is a sensor device equipped with [a specific feature / feature].

[0008] One aspect of the present invention is, The control device includes a control unit that controls the density distribution of the plurality of spots irradiated by the scanning unit until the plurality of spots irradiated by the scanning unit satisfy a first predetermined condition.

[0009] One aspect of the present invention is, This is a control method in which a computer controls the density distribution of a plurality of spots irradiated by a scanning unit until the plurality of spots irradiated by the scanning unit satisfy a first predetermined condition.

[0010] One aspect of the present invention is, This is a program that provides a computer with the function of controlling the density distribution of multiple spots irradiated by the scanning unit until the multiple spots irradiated by the scanning unit satisfy a first predetermined condition.

[0011] One aspect of the present invention is, A storage medium storing the above program. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] [Figure 1] It is a diagram showing a sensor device according to an embodiment. [Figure 2] It is a flowchart showing an example of control of a control unit according to an embodiment. [Figure 3] It is a diagram illustrating an example of the hardware configuration of the control unit. [Figure 4] It is a diagram showing a sensor device according to a modification. [Figure 5] It is a flowchart showing a first example of control of a control unit according to an example. [Figure 6] It is a diagram for explaining an example of the control shown in FIG. 5. [Figure 7] It is a diagram for explaining an example of the control shown in FIG. 5. [Figure 8] It is a flowchart showing a second example of control of a control unit according to an example. [Figure 9] It is a flowchart showing a third example of control of a control unit according to an example. [Figure 10] It is a graph for explaining an example of a first drive signal and a second drive signal for scanning a beam emitted from a light source in a second direction. [Figure 11] It is a diagram showing an example of a plurality of spots when a scanning unit is driven by the first drive signal shown in FIG. 10. [Figure 12] It is a diagram showing an example of a plurality of spots when a scanning unit is driven by the second drive signal shown in FIG. 10. MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, embodiments, modifications and examples of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same constituent elements, and the description thereof will be omitted as appropriate.

[0014] In this specification, ordinal numbers such as "first", "second", "third", etc. are used merely to distinguish between components having the same names unless otherwise specified, and do not indicate specific features (for example, order or importance) of the components.

[0015] Figure 1 is a diagram showing the sensor device 10 according to the embodiment.

[0016] In Figure 1, the arrows indicating the first direction X, the second direction Y, or the third direction Z indicate that the direction from the base end to the tip of the arrow is the positive direction in the direction indicated by the arrow, and the direction from the tip to the base end of the arrow is the negative direction in the direction indicated by the arrow.

[0017] The first direction X is a direction parallel to the horizontal direction perpendicular to the vertical direction. When viewed from the negative direction of the third direction Z, the positive direction of the first direction X is the direction from right to left in the horizontal direction, and the negative direction of the first direction X is the direction from left to right in the horizontal direction. The second direction Y is a direction parallel to the vertical direction. The positive direction of the second direction Y is the direction from bottom to top in the vertical direction, and the negative direction of the second direction Y is the direction from top to bottom in the vertical direction. The third direction Z is a direction parallel to the horizontal direction and perpendicular to the first direction X. When viewed from the negative direction of the first direction X, the positive direction of the third direction Z is the direction from left to right in the horizontal direction, and the negative direction of the third direction Z is the direction from right to left in the horizontal direction. The relationship among the first direction X, the second direction Y, the third direction Z, the horizontal direction, and the vertical direction is not limited to the above example. The relationship among the first direction X, the second direction Y, the third direction Z, the horizontal direction, and the vertical direction varies depending on the arrangement of the sensor device 10. For example, the third direction Z may be parallel to the vertical direction.

[0018] The sensor device 10 includes a scanning unit 100, a light source 110, and a control unit 200.

[0019] In this embodiment, the scanning unit 100 is a MEMS mirror that can rotate or oscillate around two predetermined orthogonal rotation axes. Specifically, the scanning unit 100 scans the beam incident on the scanning unit 100 from the light source 110 in a first direction X on a virtual plane perpendicular to a third direction Z by rotating or oscillating one of the two rotation axes. The scanning unit 100 scans the beam incident on the scanning unit 100 from the light source 110 in a second direction Y on a virtual plane perpendicular to the third direction Z by rotating or oscillating the other of the two rotation axes. The scanning unit 100 may be a different scanning unit from the MEMS mirror, such as a polygon mirror or a galvanometer mirror.

[0020] The light source 110 is, for example, a pulsed laser. The scanning unit 100 scans multiple beams emitted repeatedly over time from the light source 110 along the scan line L. The scan line L shown in Figure 1 represents a scan line projected onto a virtual plane orthogonal to the third direction Z. In Figure 1, the dashed line extending from the light source 110 through the scanning unit 100 to the scan line L indicates the direction of the beam emitted from the light source 110 at a certain timing and reflected by the scanning unit 100 toward the virtual plane. Multiple beams emitted repeatedly over time from the light source 110 are irradiated along the scan line L by the scanning unit 100, resulting in the illumination of multiple spots along the scan line L. The field of view (FOV) of the sensor device 10 includes at least a portion of the area scanned by the scanning unit 100.

[0021] The sensor device 10 detects reflected beams from multiple spots using photodetectors such as APDs (not shown). The sensor device 10 generates a point cloud using the detection results of the photodetectors and detects, recognizes, or identifies the object illuminated by the multiple spots. Hereinafter, the object detected, recognized, or identified by the sensor device 10 will be referred to as the target object, as necessary.

[0022] In one example, the sensor device 10 is a coaxial LiDAR. In this case, the optical axis of the beam irradiated from the scanning unit 100 towards multiple spots and the optical axis of the reflected beam returning from the multiple spots towards the sensor device 10 are located on the same axis. Alternatively, the sensor device 10 may be a biaxial LiDAR. In this case, the optical axis of the beam irradiated from the scanning unit 100 towards multiple spots and the optical axis of the reflected beam returning from the multiple spots towards the sensor device 10 are not on the same axis.

[0023] Figure 2 is a flowchart showing an example of the control of the control unit 200 according to the embodiment.

[0024] The control unit 200 determines whether the multiple spots irradiated by the scanning unit 100 satisfy predetermined conditions (determination step S20). The control unit 200 controls the density distribution of the multiple spots irradiated by the scanning unit 100 until the multiple spots irradiated by the scanning unit 100 satisfy predetermined conditions (No in determination step S20, control step S40). If the multiple spots irradiated by the scanning unit 100 satisfy predetermined conditions (Yes in determination step S20), the control unit 200 stops controlling the density distribution of the multiple spots. As an example, the sensor device 10 then uses the density distribution of the multiple spots after determination step S20 and control step S40 to detect, recognize, or identify a target object.

[0025] When the decision step S20 and control step S40 are performed, the target object can be detected, recognized, or identified with higher resolution compared to when the decision step S20 and control step S40 are not performed. For example, consider the case where the distance from the scanning unit 100 to the target object is relatively long. The spatial spacing of the multiple beams repeatedly emitted from the light source 110 and reflected toward the target object by the scanning unit 100 widens as they move toward the target object from the scanning unit 100. Therefore, when the distance from the scanning unit 100 to the target object is relatively long and the decision step S20 and control step S40 are not performed, the density of the multiple spots illuminating the target object becomes relatively low, and the number of multiple spots illuminating the target object may not be sufficiently large. In contrast, when the decision step S20 and control step S40 are performed, the number of multiple spots illuminating the target object can be increased by appropriately setting the predetermined conditions of the decision step S20, compared to when the decision step S20 and control step S40 are not performed. The above describes the case where the distance from the scanning unit 100 to the target object is relatively long. However, when the decision step S20 and control step S40 are performed, the target object can be detected, recognized, or identified with higher resolution compared to when the decision step S20 and control step S40 are not performed, regardless of the distance from the scanning unit 100 to the target object.

[0026] The predetermined conditions in the judgment step S20 ensure that even if the density of multiple spots irradiating the target object increases, the size of the field of view (FOV), i.e., the detection range, does not become unnecessarily small, and the density of multiple spots does not become unnecessarily high, thereby enabling the density distribution of multiple spots to be appropriately distributed. Therefore, when the judgment step S20 and control step S40 are performed, the density distribution of multiple spots can be controlled to an appropriate distribution, such as preventing the size of the FOV from becoming unnecessarily small and preventing the density of multiple spots from becoming unnecessarily high, compared to when the judgment step S20 and control step S40 are not performed.

[0027] As an example, in control step S40, the control unit 200 may control the density distribution of multiple spots by controlling the scanning speed of the scanning unit 100. For example, if the scanning unit 100 is a MEMS mirror, the scanning speed of the scanning unit 100 is determined by the angular velocity of the MEMS mirror. For example, if increasing the density distribution of multiple spots by shortening the repetition time of the beam repeatedly emitted from the light source 110 is not permitted due to factors such as eye safety, the density distribution of multiple spots is controlled by controlling the scanning speed of the scanning unit 100. Specifically, if the repetition time of the beam repeatedly emitted from the light source 110 is constant, the density of multiple spots when the scanning speed of the scanning unit 100 is slower than a predetermined speed will be higher than the density of multiple spots when the scanning speed of the scanning unit 100 is set to a predetermined speed. If the repetition time of the beam repeatedly emitted from the light source 110 is constant, the density of multiple spots when the scanning speed of the scanning unit 100 is faster than a predetermined speed will be lower than the density of multiple spots when the scanning speed of the scanning unit 100 is set to a predetermined speed. The method for controlling the density distribution of multiple spots by the control unit 200 is not limited to the example described above.

[0028] As an example, in control step S40, the control unit 200 may control the density distribution of multiple spots by controlling the overall size of the FOV. For example, when the overall size of the FOV is smaller than a predetermined size, the density of multiple spots will be higher than when the overall size of the FOV is the predetermined size. When the overall size of the FOV is larger than a predetermined size, the density of multiple spots will be lower than when the overall size of the FOV is the predetermined size. Alternatively, in control step S40, the control unit 200 may make the density distribution of multiple spots in one part of the FOV different from the density distribution of multiple spots in another part of the FOV.

[0029] As an example, in control step S40, the rate of change in the density of multiple spots by the control unit 200 may differ depending on the direction of the multiple spots. For example, if the target object is an object such as a person, which has its longitudinal direction in the second direction Y rather than the first direction X, a very high resolution in the second direction Y may not be required. In this case, the control unit 200 makes the rate of increase in the density of the multiple spots in the first direction X higher than the rate of increase in the density of the multiple spots in the second direction Y. In this control, the control unit 200 does not need to change the density distribution of the multiple spots in the second direction Y. Alternatively, for example, if the target object is an object such as a car, which has its longitudinal direction in the first direction X rather than the second direction Y, a very high resolution in the first direction X may not be required. In this case, the control unit 200 makes the rate of increase in the density of the multiple spots in the second direction Y higher than the rate of increase in the density of the multiple spots in the first direction X. In this control, the control unit 200 does not need to change the density distribution of the multiple spots in the first direction X. By appropriately varying the rate of change in the density of multiple spots by the control unit 200 according to the direction of the multiple spots, it is possible to set an appropriate coarseness and density of the multiple spots in the first direction X and the second direction Y according to the target object, thereby generating a point cloud suitable for the recognition or identification of the target object.

[0030] As an example, the control unit 200 may assign an identifier to an object detected, recognized, or identified using a point cloud generated from multiple spots. An object with an identifier can be detected, recognized, or identified by tracking processing even without irradiating it with a relatively high density of multiple spots. For this reason, after an identifier is assigned, the control unit 200 may return the density distribution of the multiple spots to the initial density distribution, i.e., the pre-control density distribution shown in Figure 2. In this case, the control unit 200 may be able to control the density distribution of the multiple spots irradiated onto an object different from the object to which the identifier was assigned.

[0031] For example, the control unit 200 may stop controlling the density distribution of multiple spots if the multiple spots irradiated by the scanning unit 100 do not meet predetermined conditions (No. in the determination step S20). After stopping the control of the density distribution of multiple spots, the control unit 200 may return the density distribution of the multiple spots to the initial density distribution, i.e., the density distribution before control shown in Figure 2. For example, when the density of at least a portion of the multiple spots reaches a predetermined upper limit due to the control of the control unit 200, the control unit 200 stops controlling the density distribution of the multiple spots. Alternatively, for example, when the time taken for the control unit 200 to perform the determination step S20 and the control step S40 reaches a predetermined upper limit time, the control unit 200 stops controlling the density distribution of the multiple spots.

[0032] As an example, the control unit 200 may stop controlling the density distribution of the multiple spots if the target object remains stationary for a predetermined time or longer. After stopping the control of the density distribution of the multiple spots, the control unit 200 may return the density distribution of the multiple spots to the initial density distribution, i.e., the pre-control density distribution shown in Figure 2. In this case, the control unit 200 can control the density distribution of the multiple spots irradiated onto an object other than the object that remained stationary for the predetermined time. For example, if the target object is a moving car but remains stationary for a predetermined time or longer, the control unit 200 can determine that the object irradiated by the multiple spots is a parked or stopped car. Alternatively, if the target object is a person but remains stationary for a predetermined time or longer, the control unit 200 can determine that the object irradiated by the multiple spots is another object that closely resembles a person.

[0033] Figure 3 illustrates the hardware configuration of the control unit 200. The control unit 200 is implemented using an integrated circuit 300. The integrated circuit 300 is, for example, a SoC (System-on-a-Chip).

[0034] The integrated circuit 300 includes a bus 302, a processor 304, a memory 306, a storage device 308, an input / output interface 310, and a network interface 312. The bus 302 is a data transmission path for the processor 304, memory 306, storage device 308, input / output interface 310, and network interface 312 to send and receive data to and from each other. However, the method of connecting the processor 304, memory 306, storage device 308, input / output interface 310, and network interface 312 to each other is not limited to bus connection. The processor 304 is an arithmetic processing unit implemented using a microprocessor or the like. The memory 306 is a memory implemented using RAM (Random Access Memory) or the like. The storage device 308 is a storage device implemented using ROM (Read Only Memory) or flash memory or the like.

[0035] The input / output interface 310 is an interface for connecting the integrated circuit 300 to peripheral devices. The scanning unit 100 is connected to the input / output interface 310.

[0036] The network interface 312 is an interface for connecting the integrated circuit 300 to a network. This network is, for example, a CAN (Controller Area Network) network. The network interface 312 may connect to the network via a wireless connection or a wired connection.

[0037] The storage device 308 stores program modules for realizing the functions of the control unit 200. The processor 304 reads these program modules into the memory 306 and executes them to realize the functions of the control unit 200.

[0038] The hardware configuration of the integrated circuit 300 is not limited to the configuration shown in Figure 3. For example, the program module may be stored in the memory 306. In this case, the integrated circuit 300 does not need to have a storage device 308.

[0039] Figure 4 shows a modified sensor device 10A. The modified sensor device 10A is the same as the sensor device 10 according to the embodiment, except for the following points.

[0040] The sensor device 10A further comprises a sensor unit 500A. The sensor unit 500A is, for example, an imaging unit such as a camera or a sensor such as a LiDAR. When the FOV of the sensor unit 500A and the FOV obtained by the scanning unit 100 are projected onto a virtual plane perpendicular to the third direction Z, at least a portion of the FOV of the sensor unit 500A overlaps with at least a portion of the FOV obtained by the scanning unit 100. Therefore, even if the FOV of the scanning unit 100 becomes narrower than the FOV of the scanning unit 100 in its initial state due to the control of the control unit 200, objects existing outside the FOV of the scanning unit 100 can be detected, recognized, or identified by the sensor unit 500A. [Examples]

[0041] Figure 5 is a flowchart showing a first example of the control of the control unit 200 according to the embodiment.

[0042] First, the control unit 200 partitions at least one region from the FOV obtained by the scanning unit 100 (partitioning step S10A). Specifically, in partitioning step S10A, the control unit 200 partitions point clouds that are relatively close to each other from other point clouds, while excluding point clouds that are unnecessary for detecting, recognizing, or identifying target objects such as people and automobiles, such as point clouds generated from multiple spots illuminated on roads, floors, walls, etc. Hereinafter, the region partitioned from the FOV obtained by the scanning unit 100 will be called the partitioned region, as necessary. The partitioned region is not limited to regions demarcated by straight lines such as rectangles or trapezoids, but may also be regions demarcated by free curves.

[0043] As an example, if multiple areas are partitioned from the FOV in partitioning step S10A, the control unit 200 may, in the determination step S20A and control step S40A described later, control the density distribution of multiple spots in the areas selected from the multiple areas partitioned from the FOV according to predetermined conditions such as risk level. For example, the control unit 200 controls the density distribution of multiple spots in at least one area selected from the multiple areas partitioned from the FOV in order of priority from high-risk areas to low-risk areas. In this control, the control unit 200 may control the density distribution of multiple spots in all areas of the multiple areas selected from the FOV, or it may not control the density distribution of multiple spots in all areas of the multiple areas selected from the FOV. For example, if the sensor device 10 is installed in a specific room for security purposes, the control unit 200 determines that areas closer to the entrance of the room have a higher risk level, and areas further from the entrance of the room have a lower risk level. In this case, the control unit 200 controls the density distribution of multiple spots in at least one area selected from the multiple areas partitioned from the FOV in order of priority from areas closer to the entrance of the room to areas further from the entrance of the room. Furthermore, for example, if the sensor device 10 is installed in a specific vehicle for autonomous driving purposes, the control unit 200 determines that the area closer to the vehicle is more dangerous, and the area further away from the vehicle is less dangerous. In this case, the control unit 200 controls the density distribution of multiple spots in at least one area selected from among multiple areas partitioned from the FOV, prioritizing areas closer to the vehicle and areas further away from the vehicle.

[0044] In one example, in partitioning step S10A, the control unit 200 may use the result of calculating the centroid position of the point cloud within the partitioned area to perform control.

[0045] After the partitioning step S10A, the control unit 200 determines whether the number of multiple spots within the partitioned area is greater than or equal to a predetermined value (determination step S20A). The control unit 200 controls the density distribution of the multiple spots until the number of multiple spots within the partitioned area is greater than or equal to a predetermined value (No in determination step S20A, control step S40A). If the number of multiple spots within the partitioned area is greater than or equal to a predetermined value (Yes in determination step S20A), the control unit 200 stops controlling the density distribution of the multiple spots.

[0046] The predetermined value in the judgment step S20A is the number of points of multiple spots necessary for detecting, recognizing, or identifying the target object, depending on the target object. Therefore, when the judgment step S20A and control step S40A are performed, the target object can be detected, recognized, or identified with higher resolution compared to when the judgment step S20A and control step S40A are not performed.

[0047] The predetermined value in the judgment step S20A can be set to a value that ensures an appropriate distribution of the density distribution of multiple spots, such that even if the density of multiple spots irradiating the target object increases, the size of the field of view (FOV) does not become unnecessarily small, and the density of multiple spots does not become unnecessarily high. Therefore, when the judgment step S20A and control step S40A are performed, the density distribution of multiple spots can be controlled to an appropriate distribution, such as preventing the size of the FOV from becoming unnecessarily small or the density of multiple spots from becoming unnecessarily high, compared to when the judgment step S20A and control step S40A are not performed.

[0048] The predetermined value in the determination step S20A may be the total number of spots within the partitioned area, or it may be the number of predetermined directions such as the first direction X and the second direction Y of the spots within the partitioned area. For example, if the target object is an object such as a person, which has its longitudinal direction in the second direction Y rather than the first direction X, a very high resolution in the second direction Y may not be required. In this case, the predetermined value in the determination step S20A may be the number of spots within the partitioned area in the first direction X. Alternatively, for example, if the target object is an object such as a car, which has its longitudinal direction in the first direction X rather than the second direction Y, a very high resolution in the first direction X may not be required. In this case, the predetermined value in the determination step S20A may be the number of spots within the partitioned area in the second direction Y.

[0049] Figures 6 and 7 illustrate an example of the control shown in Figure 5.

[0050] In Figures 6 and 7, the circles with an X indicating the third direction Z represent the positive direction of the third direction Z when moving from the front to the back of the paper, and the negative direction of the third direction Z when moving from the back to the front of the paper.

[0051] In Figures 6 and 7, the scanning unit 100 illuminates the target object Q, which is a person, with multiple spots P. In Figure 6, the multiple spots P are arranged in three columns in the first direction X and four rows in the second direction Y. In Figure 7, the multiple spots P are arranged in five columns in the first direction X and four rows in the second direction Y.

[0052] First, as a partitioning step S10A, in the example shown in Figure 6, the control unit 200 partitions at least one spot P irradiated onto the target object Q from at least one spot P not irradiated onto the target object Q. In the example shown in Figure 6, at least a portion of one spot P in the first column from the positive side of the first direction X and the second row from the positive side of the second direction Y, at least a portion of each of the four spot Ps in the second column from the positive side of the first direction X and the first, second, third, and fourth rows from the positive side of the second direction Y, and at least a portion of one spot P in the third column from the positive side of the first direction X and the second row from the positive side of the second direction Y are irradiated onto the target object Q. The control unit 200 identifies a partitioned region containing these spots P irradiated onto the target object Q.

[0053] Next, in the determination step S20A, the control unit 200 determines whether the number of spots P within the partitioned area in the example shown in Figure 6 is greater than or equal to a predetermined value. For example, if the predetermined value in determination step S20A is the total number of spots P within the partitioned area, the control unit 200 determines whether the total number of spots P within the partitioned area, 6, in the example shown in Figure 6 is greater than or equal to the predetermined value. Alternatively, for example, if the predetermined value in determination step S20A is the number of spots P within the partitioned area in the first direction X, the control unit 200 determines whether the number of spots P within the partitioned area in the first direction X, 3, in the example shown in Figure 6 is greater than or equal to the predetermined value.

[0054] If, in the judgment step S20A, the control unit 200 determines that the number of spots P within the partitioned area in the example shown in Figure 6 is not equal to or greater than a predetermined value, then in the control step S40A, the control unit 200 controls the system to increase the number of spots P within the partitioned area from the state shown in Figure 6 to the state shown in Figure 7. From the state shown in Figure 6 to the state shown in Figure 7, the control unit 200 increases the number of spots P within the partitioned area in the first direction X, while keeping the number of spots P within the partitioned area in the second direction Y unchanged. In the example shown in Figure 7, the target object Q is illuminated by at least a portion of one spot P in the first column from the positive side of the first direction X and the second row from the positive side of the second direction Y, at least a portion of each of the 12 spots P in the second, third, and fourth columns from the positive side of the first direction X and the first, second, third, and fourth rows from the positive side of the second direction Y, and at least a portion of one spot P in the fifth column from the positive side of the first direction X and the second row from the positive side of the second direction Y.

[0055] Next, as a determination step S20A, the control unit 200 determines whether the number of spots P within the partitioned area is greater than or equal to a predetermined value, in the same manner as the determination step S20A explained using Figure 6. In the example shown in Figure 7, if the control unit 200 determines that the number of spots P within the partitioned area is greater than or equal to a predetermined value, the control unit 200 stops controlling the density distribution of the multiple spots P within the partitioned area.

[0056] Next, the sensor device 10 detects, recognizes, or identifies the target object Q using multiple spots P with the density distribution shown in Figure 7.

[0057] Figure 8 is a flowchart showing a second example of the control of the control unit 200 according to the embodiment.

[0058] First, the control unit 200 performs partitioning step S10B in the same manner as partitioning step S10A in the flowchart shown in Figure 5.

[0059] Next, the control unit 200 determines whether the detection, recognition, or identification of an object using the point cloud generated from multiple spots within the partitioned area is successful (determination step S20B). The control unit 200 controls the density distribution of the multiple spots until the detection, recognition, or identification of an object using the point cloud generated from multiple spots within the partitioned area is successful (No in determination step S20B, control step S40B). If the detection, recognition, or identification of an object using the point cloud generated from multiple spots within the partitioned area is successful (Yes in determination step S20B), the control unit 200 stops controlling the density distribution of the multiple spots.

[0060] For example, if the control unit 200 fails to detect, recognize, or identify an object using the point cloud generated from multiple spots within the partitioned area (No. in decision step S20B), it may stop controlling the density distribution of the multiple spots. After stopping the control of the density distribution of the multiple spots, the control unit 200 may return the density distribution of the multiple spots to its initial density distribution, i.e., the pre-control density distribution shown in Figure 8. For example, when the density of at least a portion of the multiple spots reaches a predetermined upper limit due to the control of the control unit 200, the control unit 200 stops controlling the density distribution of the multiple spots. Alternatively, for example, when the time taken for the control unit 200 to perform decision step S20B and control step S40B reaches a predetermined upper limit time, the control unit 200 stops controlling the density distribution of the multiple spots.

[0061] When performing the judgment step S20B and the control step S40B, the density of multiple spots irradiated onto the target object is increased until detection, recognition, or identification of the object within the partitioned area is successful. The success or failure of detecting, recognizing, or identifying the target object is determined, for example, by subjecting the point cloud generated using the reflected beams from the multiple spots irradiated onto the target object to recognition processing such as machine learning. Alternatively, for example, based on the relationship between the size of the object to be detected, recognized, or identified and the distance from the scanning unit 100 to the centroid position of the multiple spots within the partitioned area, the angular pitch of the multiple beams irradiated from the scanning unit 100 to the multiple spots within the partitioned area, which will result in successful detection, recognition, or identification of the object within the partitioned area, may be predetermined from the results of machine learning, etc. In this case, the control unit 200 can control the angular pitch of the multiple beams irradiated from the scanning unit 100 to the pitch necessary for successful detection, recognition, or identification of the object within the partitioned area.

[0062] When the decision step S20B and control step S40B are performed, the increase in the density of multiple spots can be stopped before the density distribution of multiple spots deviates from an appropriate distribution, such as when the size of the FOV becomes unnecessarily small or the density of multiple spots becomes unnecessarily high. Therefore, when the decision step S20B and control step S40B are performed, the density distribution of multiple spots can be controlled to an appropriate distribution, such as when the size of the FOV does not become unnecessarily small or the density of multiple spots does not become unnecessarily high, compared to when the decision step S20B and control step S40B are not performed.

[0063] Figure 9 is a flowchart showing a third example of the control of the control unit 200 according to the embodiment.

[0064] First, the control unit 200 performs partition step S10C in the same manner as partition step S10A in the flowchart shown in Figure 5.

[0065] Next, the control unit 200 determines whether the overlap rate of multiple spots within the partitioned area is greater than or equal to a predetermined value (determination step S20C). The control unit 200 controls the density distribution of the multiple spots until the overlap rate of multiple spots within the partitioned area is greater than or equal to a predetermined value (No in determination step S20C, control step S40C). For example, if the density of multiple spots is increased as shown in Figure 7, at least a portion of adjacent spots within the multiple spots may overlap. The overlap rate of the multiple spots for the first and second spots that overlap at least a portion is the ratio of the sum of the area of ​​the portion of the first spot that overlaps with the second spot and the sum of the area of ​​the portion of the second spot that overlaps with the first spot, to the sum of the area of ​​the first spot and the area of ​​the second spot. If the overlap rate of multiple spots within the partitioned area is greater than or equal to a predetermined value (Yes in determination step S20C), the control unit 200 stops controlling the density distribution of the multiple spots.

[0066] The predetermined value in the judgment step S20C is the overlap rate of multiple spots that does not cause any inconvenience in detecting, recognizing, or identifying the target object, depending on the target object. Therefore, when the judgment step S20C and control step S40C are performed, the target object can be detected, recognized, or identified with higher resolution compared to when the judgment step S20C and control step S40C are not performed.

[0067] The predetermined value in the judgment step S20C can be set to a value that ensures an appropriate distribution of the density of multiple spots, such that even if the density of multiple spots irradiating the target object increases, the size of the field of view (FOV) does not become unnecessarily small, and the density of multiple spots does not become unnecessarily high. Even if the overlap rate of multiple spots exceeds the predetermined value, the actual resolution does not improve. Furthermore, if the overlap rate of multiple spots exceeds the predetermined value, the possibility of false detection, misrecognition, or misidentification of an object may increase. Therefore, when the judgment step S20C and control step S40C are performed, the density distribution of multiple spots can be controlled to an appropriate distribution, such as preventing the size of the FOV from becoming unnecessarily small or the density of multiple spots from becoming unnecessarily high, compared to when the judgment step S20C and control step S40C are not performed.

[0068] Figure 10 is a graph illustrating an example of a first drive signal S1 and a second drive signal S2 for scanning the beam emitted from the light source 110 in a second direction Y. Figure 11 is a diagram showing an example of multiple spots when the scanning unit 100 is driven by the first drive signal S1 shown in Figure 10. Figure 12 is a diagram showing an example of multiple spots when the scanning unit 100 is driven by the second drive signal S2 shown in Figure 10.

[0069] In Figure 10, the horizontal axis of the graph represents time. The vertical axis of the graph represents the intensity of the drive signal. In this graph, the upward direction on the vertical axis represents the positive drive signal, and the downward direction on the vertical axis represents the negative drive signal. In Figure 10, the scanning time interval TFOV, which ranges from a time slightly after the time when the first drive signal S1 takes its maximum value to a time slightly before the time when the first drive signal S1 takes its next minimum value, represents the time interval in which multiple beams are repeatedly emitted from the light source 110 toward the scanning unit 100, i.e., the measurement time interval.

[0070] Figures 11 and 12 show the FOV projected onto a virtual plane perpendicular to the third direction Z. In Figure 11, multiple first scan lines LA aligned in the second direction Y are shown within the FOV. Each of the multiple first scan lines LA within the FOV is illuminated by at least one spot. In Figure 11, for illustrative purposes, spots PA illuminated along three first scan lines LA in the central part of the FOV are shown as white circles. In Figure 12, multiple second scan lines LB aligned in the second direction Y are shown within the FOV. Each of the multiple second scan lines LB within the FOV is illuminated by at least one spot. In Figure 12, for illustrative purposes, spots PB illuminated along three second scan lines LB in the central part of the FOV are shown as white circles.

[0071] As shown in Figure 10, the first drive signal S1 has a triangular wave shape. The first drive signal S1 has a uniform slope in the scanning time interval TFOV. In the FOV shown in Figure 11, from the beginning to the end of the scanning time interval TFOV, the scanning unit 100 scans multiple beams repeatedly emitted from the light source 110 from the positive side of the second direction Y to the negative side of the second direction Y. Because the slope of the first drive signal S1 in the scanning time interval TFOV is uniform, the multiple first scan lines LA in the FOV shown in Figure 11 are arranged at equal intervals in the second direction Y.

[0072] As shown in Figure 10, the second drive signal S2 has a deformed triangular wave shape. Specifically, the slope of the second drive signal S2 in the central section of the scanning time interval TFOV is smaller than the slope of the first drive signal S1 in the scanning time interval TFOV. Also, the slope of the second drive signal S2 in the sections on both sides of the central section of the scanning time interval TFOV is larger than the slope of the first drive signal S1 in the scanning time interval TFOV. In the FOV shown in Figure 12, from the beginning to the end of the scanning time interval TFOV, the scanning unit 100 scans multiple beams repeatedly emitted from the light source 110 shown in Figure 1 or Figure 4 from the positive side to the negative side of the second direction Y. Because the slope of the second drive signal S2 in the central section of the scan time interval TFOV is smaller than the slope of the first drive signal S1 in the scan time interval TFOV, the spacing of the multiple second scan lines LB in the second direction Y in the central part of the FOV shown in Figure 12 is narrower than the spacing of the multiple first scan lines LA in the second direction Y in the FOV shown in Figure 11. Also, because the slope of the second drive signal S2 in the sections on both sides of the central section of the scan time interval TFOV is larger than the slope of the first drive signal S1 in the scan time interval TFOV, the spacing of the multiple second scan lines LB in the second direction Y in the upper and lower sections of the FOV shown in Figure 12 is wider than the spacing of the multiple first scan lines LA in the second direction Y in the FOV shown in Figure 11.

[0073] As shown in Figure 12, the control unit 200 makes the density distribution of multiple spots in the central part of the second direction Y within the FOV different from the density distribution of multiple spots in the central part of the second direction Y within the FOV. The control of the density distribution of multiple spots by the control unit 200 is not limited to the example shown in Figure 12. Whether the spacing of the multiple second scan lines LB shown in Figure 12 in the second direction Y within the FOV is narrower than the spacing of the multiple first scan lines LA shown in Figure 11 is determined according to which time interval in the scanning time interval TFOV the slope of the second drive signal S2 is made smaller than the slope of the first drive signal S1. Therefore, depending on which time interval in the scanning time interval TFOV the slope of the second drive signal S2 is made smaller than the slope of the first drive signal S1, the control unit 200 can make the density distribution of multiple spots in one part of the FOV different from the density distribution of multiple spots in another part of the FOV.

[0074] The embodiments, modifications, and examples of the present invention have been described above with reference to the drawings, but these are merely examples of the present invention, and various other configurations can also be adopted.

[0075] This application claims priority based on Japanese Patent Application No. 2021-038057, filed on 10 March 2021, and incorporates all of its disclosures herein. [Explanation of Symbols]

[0076] 10 Sensor device 10A Sensor Device 100 Scanning Unit 110 Light source 200 Control Unit 300 Integrated Circuits Bus 302 304 Processors 306 memory 308 storage devices 310 Input / Output Interfaces 312 Network Interfaces 500A Sensor Unit L scan line LA First scan line LB 2nd scan line P Spot PA Spot PB Spot Q target object S1 First drive signal S10A Partition Step S10B Partition Step S10C Partition Step S2 Second drive signal S20 Decision Step S20A Decision Step S20B Decision Step S20C Decision Step S40 Control Step S40A Control Step S40B Control Step S40C Control Step TFOV scan time interval X 1st direction Y Second direction Z 3rd direction

Claims

[Claim 1] Scanning unit and, A control unit controls the density distribution of the plurality of spots irradiated by the scanning unit until the plurality of spots irradiated by the scanning unit satisfy a first predetermined condition, A sensor device equipped with the following features.

Images