Sensor device

Abstract

To control the density distribution of a plurality of spots into an appropriate distribution.SOLUTION: A control unit 200 determines whether or not a plurality of spots to be irradiated by a scanning unit 100 satisfy a prescribed condition. The control unit 200 controls the density distribution of the plurality of spots to be irradiated by the scanning unit 100 until the plurality of spots to be irradiated by the scanning unit 100 satisfy the prescribed condition.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In recent years, various sensor devices such as LiDAR (Light Detection And Ranging) have been developed. The sensor device includes a scanning unit such as a MEMS (Micro Electro Mechanical Systems) mirror. The scanning unit reflects multiple beams repeatedly emitted from a light source such as a pulsed laser, and irradiates multiple spots within a field of view (FOV). The sensor device detects the reflected beams from the multiple spots with a light detection element such as an APD (Avalanche Photodiode). The sensor device generates a point cloud using the detection results of the light detection element, and detects, recognizes, or identifies an object irradiated with the multiple 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 in a spatially uniform manner within the FOV. The second LiDAR irradiates a plurality of beams in a spatially non-uniform manner within the FOV. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2019-526056 Summary of the Invention [Problem to be solved by the invention]

[0005] By controlling the density distribution of the multiple spots irradiated on an object and increasing the density of the multiple spots, the object may be detected, recognized, or identified with a relatively high resolution. However, simply increasing the density of the multiple spots may result in an inappropriate density distribution of the multiple spots, such as a narrower FOV, which may result in an object detection range being narrower than necessary, or a higher density of the multiple spots being higher than necessary.

[0006] One example of a problem to be solved by the present invention is how to control the density distribution of a plurality of spots to an appropriate distribution. [Means for solving the problem]

[0007] The invention described in claim 1 is A scanning unit; a control unit that controls a density distribution of the plurality of spots irradiated by the scanning unit until the plurality of spots irradiated by the scanning unit satisfies a first predetermined condition; The sensor device includes:

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

[0009] One aspect of the present invention is The control method includes controlling a 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 The program provides a computer with a function of controlling the density distribution of the 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] FIG. 1 is a diagram showing a sensor device according to an embodiment. [Diagram 2] 6 is a flowchart illustrating an example of control by a control unit according to the embodiment. [Diagram 3] FIG. 2 is a diagram illustrating an example of a hardware configuration of a control unit. [Figure 4] FIG. 13 is a diagram showing a sensor device according to a modified example. [Diagram 5] 5 is a flowchart showing a first example of control by a control unit according to the embodiment. [Figure 6] FIG. 6 is a diagram for explaining an example of the control shown in FIG. 5. [Figure 7] FIG. 6 is a diagram for explaining an example of the control shown in FIG. 5. [Figure 8] 10 is a flowchart showing a second example of control by the control unit according to the embodiment. [Figure 9] 10 is a flowchart showing a third example of control by the control unit according to the embodiment. [Figure 10] 10 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] 11 is a diagram showing an example of a plurality of spots when a scanning unit is driven by the first driving signal shown in FIG. [Figure 12] 11 is a diagram showing an example of a plurality of spots when the scanning unit is driven by the second driving signal shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0014] In this specification, ordinal numbers such as "first," "second," "third," etc., unless otherwise specified, are used merely to distinguish between similarly named configurations and do not imply any particular characteristics (e.g., order or importance) of the configurations.

[0015] FIG. 1 is a diagram showing a sensor device 10 according to an embodiment.

[0016] In FIG. 1, an arrow indicating the first direction X, the second direction Y, or the third direction Z indicates that the direction from the base end of the arrow to the tip end of the arrow is the positive direction of the direction indicated by the arrow, and that the direction from the tip of the arrow to the base end of the arrow is the negative direction of 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 a direction from right to left in the horizontal direction, and the negative direction of the first direction X is a 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 a direction from bottom to top in the vertical direction, and the negative direction of the second direction Y is a 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 a direction from left to right in the horizontal direction, and the negative direction of the third direction Z is a direction from right to left in the horizontal direction. The relationship between 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 between 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 swing around two orthogonal predetermined rotation axes. Specifically, the scanning unit 100 rotates or swings one of the two rotation axes to scan the beam incident on the scanning unit 100 from the light source 110 in the first direction X on a virtual plane perpendicular to the third direction Z. The scanning unit 100 rotates or swings the other of the two rotation axes to scan the beam incident on the scanning unit 100 from the light source 110 in the second direction Y on a virtual plane perpendicular to the third direction Z. The scanning unit 100 may be a scanning unit other than the MEMS mirror, such as a polygon mirror or a galvanometer mirror.

[0020] The light source 110 is, for example, a pulse laser. The scanning unit 100 scans a plurality of beams emitted from the light source 110 repeatedly over time along a scanning line L. The scanning line L shown in FIG. 1 indicates a scanning line projected onto a virtual plane perpendicular to the third direction Z. In FIG. 1, a dashed line extending from the light source 110 through the scanning unit 100 to the scanning line L indicates a direction of a beam emitted from the light source 110 at a certain timing and reflected by the scanning unit 100 toward the virtual plane. The plurality of beams emitted from the light source 110 repeatedly over time are irradiated along the scanning line L by the scanning unit 100, so that a plurality of spots are irradiated along the scanning line L. The field of view (FOV) of the sensor device 10 has at least a part of the area scanned by the scanning unit 100.

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

[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 to the multiple spots and the optical axis of the reflected beam returning from the multiple spots to 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 to the multiple spots and the optical axis of the reflected beam returning from the multiple spots to the sensor device 10 are not located on the same axis.

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

[0024] The control unit 200 judges whether the multiple spots irradiated by the scanning unit 100 satisfy a predetermined condition (judgment 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 the predetermined condition (No in judgment step S20, control step S40). If the multiple spots irradiated by the scanning unit 100 satisfy the predetermined condition (Yes in judgment step S20), the control unit 200 stops controlling the density distribution of the multiple spots. As an example, the sensor device 10 then detects, recognizes, or identifies a target object using the multiple spots of the density distribution in a state after the judgment step S20 and the control step S40.

[0025] When the determination step S20 and the control step S40 are performed, the target object can be detected, recognized, or identified with a higher resolution than when the determination step S20 and the control step S40 are not performed. For example, assume that the distance from the scanning unit 100 to the target object is relatively long. The spatial intervals of the multiple beams repeatedly emitted from the light source 110 and reflected by the scanning unit 100 toward the target object widen as they move from the scanning unit 100 to the target object. Therefore, when the distance from the scanning unit 100 to the target object is relatively long and the determination step S20 and the control step S40 are not performed, the density of the multiple spots irradiated to the target object becomes relatively low, and the number of the multiple spots irradiated to the target object may not be sufficiently large. In contrast, when the determination step S20 and the control step S40 are performed, the number of the multiple spots irradiated to the target object can be increased by appropriately setting the predetermined conditions of the determination step S20 compared to when the determination step S20 and the 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 judgment step S20 and the control step S40 are performed, the target object can be detected, recognized or identified with high resolution, regardless of the distance from the scanning unit 100 to the target object, compared to when the judgment step S20 and the control step S40 are not performed.

[0026] The predetermined condition in the judgment step S20 can make the density distribution of the multiple spots appropriate, such as not making the size of the FOV, i.e., the detection range, smaller than necessary, not making the density of the multiple spots higher than necessary, even if the density of the multiple spots irradiated on the target object increases. Therefore, when the judgment step S20 and the control step S40 are performed, the density distribution of the multiple spots can be controlled to an appropriate distribution, such as not making the size of the FOV smaller than necessary, not making the density of the multiple spots higher than necessary, etc., compared to the case where the judgment step S20 and the control step S40 are not performed.

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

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

[0029] As an example, in the control step S40, the rate of change of the density of the multiple spots by the control unit 200 may differ depending on the direction of the multiple spots. For example, when the target object is an object having a longer direction in the second direction Y than the first direction X, such as a person, a resolution that is not very high in the second direction Y may not be required. In this case, the control unit 200 makes the increase rate of the density of the multiple spots in the first direction X higher than the increase rate of the density of the multiple spots in the second direction Y. In this control, the control unit 200 may not change the density distribution of the multiple spots in the second direction Y. Alternatively, for example, when the target object is an object having a longer direction in the first direction X than the second direction Y, such as a car, a resolution that is not very high in the first direction X may not be required. In this case, the control unit 200 makes the increase rate of the density of the multiple spots in the second direction Y higher than the increase rate of the density of the multiple spots in the first direction X. In this control, the control unit 200 may not change the density distribution of the multiple spots in the first direction X. By appropriately varying the rate of change in density of the multiple spots by the control unit 200 depending on the direction of the multiple spots, it is possible to set appropriate density levels of the multiple spots in the first direction X and the second direction Y depending on the target object, and to generate a point cloud suitable for recognizing or identifying 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 the plurality of spots. The object to which the identifier is assigned may be detected, recognized, or identified by a tracking process without irradiating the object with a relatively high density of the plurality of spots. For this reason, after the identifier is assigned, the control unit 200 may return the density distribution of the plurality of spots to the initial density distribution, that is, the density distribution before control shown in FIG. 2. In this case, the control unit 200 may be able to control the density distribution of the plurality of spots irradiated to an object other than the object to which the identifier is assigned.

[0031] As an example, the control unit 200 may stop the control of the density distribution of the multiple spots when the multiple spots irradiated by the scanning unit 100 do not satisfy a predetermined condition (No in the judgment step S20). 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 an initial density distribution, that is, the density distribution before the control shown in FIG. 2. For example, when the density of at least a part of the multiple spots reaches a predetermined upper limit value by the control of the control unit 200, the control unit 200 stops the control of the density distribution of the multiple spots. Alternatively, for example, when the time during which the control unit 200 performs the judgment step S20 and the control step S40 reaches a predetermined upper limit time, the control unit 200 stops the control of the density distribution of the multiple spots.

[0032] As an example, the control unit 200 may stop the control of the density distribution of the multiple spots when the target object remains stationary for a predetermined time or more. 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, that is, the density distribution before the control shown in FIG. 2. In this case, the control unit 200 can control the density distribution of the multiple spots irradiated to another object different from the object that has been stationary for a predetermined time. For example, when a moving automobile is set as the target object but the target object remains stationary for a predetermined time or more, the control unit 200 can determine that the object on which the multiple spots are irradiated is a parked or stopped automobile. Alternatively, when a person is set as the target object but the target object remains stationary for a predetermined time or more, the control unit 200 can determine that the object on which the multiple spots are irradiated is another object similar to a person.

[0033] 3 is a diagram illustrating an example of a 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 System-on-a-Chip (SoC).

[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, the memory 306, the storage device 308, the input / output interface 310, and the network interface 312 to transmit and receive data to and from each other. However, the method of connecting the processor 304, the memory 306, the storage device 308, the input / output interface 310, and the network interface 312 to each other is not limited to a bus connection. The processor 304 is an arithmetic processing device realized by using a microprocessor or the like. The memory 306 is a memory realized by using a RAM (Random Access Memory) or the like. The storage device 308 is a storage device realized by using a ROM (Read Only Memory), a flash memory, or the like.

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

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

[0037] The storage device 308 stores program modules for implementing the functions of the control unit 200. The processor 304 implements the functions of the control unit 200 by reading these program modules into the memory 306 and executing them.

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

[0039] 4 is a diagram showing a sensor device 10A according to a modified example. The sensor device 10A according to the modified example is similar to the sensor device 10 according to the embodiment, except for the following points.

[0040] The sensor device 10A further includes 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 in the initial state of the scanning unit 100 due to the control of the control unit 200, an object existing outside the FOV of the scanning unit 100 can be detected, recognized, or identified by the sensor unit 500A. EXAMPLES

[0041] FIG. 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 divides at least one region from the FOV obtained by the scanning unit 100 (division step S10A). Specifically, in the division step S10A, the control unit 200 divides point clouds that are relatively close to each other from other point clouds, while removing point clouds that are unnecessary for detecting, recognizing, or identifying target objects such as people and automobiles, such as point clouds generated from a plurality of spots irradiated on a road, floor, wall, etc. Hereinafter, as necessary, a region divided from the FOV obtained by the scanning unit 100 is referred to as a divided region. The divided region is not limited to a region divided by straight lines such as a rectangle or a trapezoid, but may be a region divided by a free curve.

[0043] As an example, when a plurality of regions are partitioned from the FOV in the partition step S10A, the control unit 200 may control the density distribution of a plurality of spots in a region selected from the plurality of regions partitioned from the FOV according to a predetermined condition such as a danger level in a judgment step S20A and a control step S40A described later. For example, the control unit 200 controls the density distribution of a plurality of spots in at least one region selected from the plurality of regions partitioned from the FOV in a priority order from a region with a high danger level to a region with a low danger level. In this control, the control unit 200 may control the density distribution of a plurality of spots in all of the plurality of regions selected from the FOV, or may not control the density distribution of a plurality of spots in all of the plurality of regions selected from the FOV. For example, when the sensor device 10 is installed in a specific room for security purposes, the control unit 200 determines that the closer to the entrance of the room, the higher the danger level, and the farther from the entrance of the room, the lower the danger level. In this case, the control unit 200 controls the density distribution of a plurality of spots in at least one region selected from the plurality of regions partitioned from the FOV in a priority order from a region with a high danger level to a region with a low danger level. Also, for example, when the sensor device 10 is installed in a specific automobile for the purpose of automatic driving, the control unit 200 determines that the closer to the automobile the higher the risk is, and the farther from the automobile the lower the risk is. In this case, the control unit 200 controls the density distribution of the multiple spots in at least one area selected from multiple areas partitioned from the FOV in the order of priority from the area closer to the automobile to the area farther from the automobile.

[0044] In one example, in the partitioning step S10A, the control unit 200 may perform control using the result of calculating the center of gravity of the point cloud within the partitioned region.

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

[0046] The predetermined value in the decision step S20A is the number of points of the plurality of spots required for detecting, recognizing or identifying the target object according to the target object. Therefore, when the decision step S20A and the control step S40A are performed, the target object can be detected, recognized or identified with a higher resolution than when the decision step S20A and the control step S40A are not performed.

[0047] The predetermined value in the judgment step S20A can be set to a value that makes the density distribution of the multiple spots appropriate, such as not making the size of the FOV smaller than necessary, not making the density of the multiple spots higher than necessary, even if the density of the multiple spots irradiated on the target object increases. Therefore, when the judgment step S20A and the control step S40A are performed, the density distribution of the multiple spots can be controlled to an appropriate distribution, such as not making the size of the FOV smaller than necessary, not making the density of the multiple spots higher than necessary, etc., compared to when the judgment step S20A and the control step S40A are not performed.

[0048] The predetermined value in the determination step S20A may be the total number of the spots in the divided area, or may be the number of the spots in the divided area in a predetermined direction, such as the first direction X or the second direction Y. For example, when the target object is an object having a longer direction in the second direction Y than the first direction X, such as a person, a resolution that is not very high 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 the spots in the first direction X in the divided area. Alternatively, when the target object is an object having a longer direction in the first direction X than the second direction Y, such as a car, a resolution that is not very high 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 the spots in the second direction Y in the divided area.

[0049] 6 and 7 are diagrams for explaining an example of the control shown in FIG.

[0050] 6 and 7, the circle with an X indicating the third direction Z indicates that the direction from the front of the paper to the back is the positive direction of the third direction Z, and the direction from the back of the paper to the front is the negative direction of the third direction Z.

[0051] 6 and 7, a plurality of spots P are irradiated onto a target object Q, which is a person, by the scanning unit 100. In Fig. 6, the plurality of spots P are arranged in three columns in the first direction X and four rows in the second direction Y. In Fig. 7, the plurality of spots P are arranged in five columns in the first direction X and four rows in the second direction Y.

[0052] First, in the partitioning step S10A, in the example shown in Fig. 6, the control unit 200 partitions at least one spot P irradiated on the target object Q from at least one spot P not irradiated on the target object Q. In the example shown in Fig. 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 four spots P 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 on the target object Q. The control unit 200 specifies a partitioned area including these spots P irradiated on the target object Q.

[0053] Next, in judgment step S20A, the control unit 200 judges whether the number of spots P in the defined area is equal to or greater than a predetermined value in the example shown in Fig. 6. For example, if the predetermined value in judgment step S20A is the total number of spots P in the defined area, the control unit 200 judges whether the total number of spots P in the defined area (6) in the example shown in Fig. 6 is equal to or greater than the predetermined value. Alternatively, for example, if the predetermined value in judgment step S20A is the number of spots P in the first direction X in the defined area, the control unit 200 judges whether the number of spots P in the first direction X in the defined area (3) in the example shown in Fig. 6 is equal to or greater than the predetermined value.

[0054] If the control unit 200 determines in judgment step S20A that the number of spots P in the defined area in the example shown in Fig. 6 is not equal to or greater than a predetermined value, then in control step S40A, the control unit 200 controls to increase the number of spots P in the defined area from the state shown in Fig. 6 to the state shown in Fig. 7. From the state shown in Fig. 6 to the state shown in Fig. 7, the control unit 200 increases the number of spots P in the first direction X in the defined area without changing the number of spots P in the second direction Y in the defined area. In the example shown in FIG. 7, at least a portion of one spot P in the first column from the positive side in the first direction X and the second row from the positive side in the second direction Y, at least a portion of each of 12 spots P in the second, third, and fourth columns from the positive side in the first direction X and the first, second, third, and fourth rows from the positive side in the second direction Y, and at least a portion of one spot P in the fifth column from the positive side in the first direction X and the second row from the positive side in the second direction Y are irradiated onto the target object Q.

[0055] Next, in judgment step S20A, the control unit 200 judges whether or not the number of spots P in the divided area is equal to or greater than a predetermined value, similarly to judgment step S20A described with reference to Fig. 6. In the example shown in Fig. 7, when the control unit 200 judges that the number of spots P in the divided area is equal to or greater than a predetermined value, the control unit 200 stops controlling the density distribution of the multiple spots P in the divided area.

[0056] The sensor device 10 then detects, recognizes or identifies a target object Q using the multiple spots P of the density distribution shown in FIG.

[0057] FIG. 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 the partition step S10B in the same manner as the partition step S10A in the flowchart shown in FIG.

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

[0060] As an example, the control unit 200 may stop the control of the density distribution of the multiple spots when the detection, recognition, or identification of an object using the point cloud generated from the multiple spots in the divided area is not successful (No in the judgment step S20B). 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 an initial density distribution, that is, the density distribution before the control shown in FIG. 8. For example, when the density of at least a part of the multiple spots reaches a predetermined upper limit value due to the control of the control unit 200, the control unit 200 stops the control of the density distribution of the multiple spots. Alternatively, for example, when the time during which the control unit 200 performs the judgment step S20B and the control step S40B reaches a predetermined upper limit time, the control unit 200 stops the control of the density distribution of the multiple spots.

[0061] When performing the determination step S20B and the control step S40B, the density of the multiple spots irradiated to the target object is increased until the detection, recognition, or identification of the object in the divided area is successful. The success or failure of the detection, recognition, or identification of the target object is determined, for example, by subjecting a point cloud generated using reflected beams from the multiple spots irradiated to the target object to a recognition process 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 center of gravity of the multiple spots in the divided area, it may be determined in advance from the results of machine learning or the like as to which angular pitch of the multiple beams irradiated from the scanning unit 100 to the multiple spots in the divided area will enable the detection, recognition, or identification of the object in the divided area to be successful. In this case, the control unit 200 can control the angular pitch of the multiple beams irradiated from the scanning unit 100 to the multiple spots in the divided area to a pitch that enables the detection, recognition, or identification of the object in the divided area to be successful.

[0062] When the determination step S20B and the control step S40B are performed, the increase in the density of the multiple spots can be stopped before the density distribution of the multiple spots deviates from an appropriate distribution, such as the size of the FOV becoming smaller than necessary, the density of the multiple spots becoming higher than necessary, etc. Therefore, when the determination step S20B and the control step S40B are performed, the density distribution of the multiple spots can be controlled to an appropriate distribution, such as the size of the FOV not becoming smaller than necessary, the density of the multiple spots not becoming higher than necessary, etc., compared to the case where the determination step S20B and the control step S40B are not performed.

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

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

[0065] Next, the control unit 200 judges whether the overlap rate of the multiple spots in the divided area is equal to or greater than a predetermined value (judgment step S20C). The control unit 200 controls the density distribution of the multiple spots until the overlap rate of the multiple spots in the divided area becomes equal to or greater than a predetermined value (No in judgment step S20C, control step S40C). For example, when the density of the multiple spots is increased as shown in FIG. 7, adjacent spots among the multiple spots may at least partially overlap. The overlap rate of the multiple spots for the first spot and the second spot that at least partially overlap is the ratio of the sum of the area of ​​the first spot that overlaps with the second spot and the area 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. When the overlap rate of the multiple spots in the divided area becomes equal to or greater than a predetermined value (Yes in judgment step S20C), the control unit 200 stops the control of the density distribution of the multiple spots.

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

[0067] The predetermined value in the judgment step S20C can be set to a value that allows the density distribution of the multiple spots to be appropriately distributed, such as the size of the FOV not becoming smaller than necessary or the density of the multiple spots not becoming higher than necessary even if the density of the multiple spots irradiated on the target object increases. Even if the overlap rate of the multiple spots becomes larger than the predetermined value, the actual resolution does not improve. Furthermore, if the overlap rate of the multiple spots becomes larger than the predetermined value, the possibility of erroneous detection, erroneous recognition, or erroneous identification of the object may increase. Therefore, when the judgment step S20C and the control step S40C are performed, the density distribution of the multiple spots can be appropriately controlled, such as the size of the FOV not becoming smaller than necessary or the density of the multiple spots not becoming higher than necessary, compared to the case where the judgment step S20C and the control step S40C are not performed.

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

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

[0070] 11 and 12 show the FOV projected on a virtual plane perpendicular to the third direction Z. In FIG. 11, a plurality of first scanning lines LA arranged in the second direction Y in the FOV are shown. At least one spot is irradiated on each of the plurality of first scanning lines LA in the FOV. In FIG. 11, for the sake of explanation, spots PA irradiated along the three first scanning lines LA in the central part of the FOV are shown by white circles. In FIG. 12, a plurality of second scanning lines LB arranged in the second direction Y in the FOV are shown. At least one spot is irradiated on each of the plurality of second scanning lines LB in the FOV. In FIG. 12, for the sake of explanation, spots PB irradiated along the three second scanning lines LB in the central part of the FOV are shown by white circles.

[0071] As shown in Fig. 10, the first drive signal S1 has a triangular wave shape. The first drive signal S1 has a uniform inclination in the scanning time section TFOV. In the FOV shown in Fig. 11, from the beginning to the end of the scanning time section TFOV, the scanning unit 100 scans with a plurality of 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. Since the inclination of the first drive signal S1 in the scanning time section TFOV is uniform, the plurality of first scanning lines LA are arranged at equal intervals in the second direction Y in the FOV shown in Fig. 11.

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

[0073] As shown in FIG. 12, the control unit 200 makes the density distribution of the multiple spots in the center part of the FOV in the second direction Y different from the density distribution of the multiple spots in both sides of the center part of the FOV in the second direction Y. The control of the density distribution of the multiple spots by the control unit 200 is not limited to the example shown in FIG. 12. In which part of the second direction Y in the FOV, the interval in the second direction Y of the multiple second scanning lines LB shown in FIG. 12 is narrower than the interval in the second direction Y of the multiple first scanning lines LA shown in FIG. 11 is determined depending on which time period in the scanning time section TFOV the slope of the second driving signal S2 is made smaller than the slope of the first driving signal S1. Therefore, depending on which time period in the scanning time section TFOV the slope of the second driving signal S2 is made smaller than the slope of the first driving signal S1, the control unit 200 can make the density distribution of the multiple spots in one part of the FOV different from the density distribution of the multiple spots in another part of the FOV.

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

[0075] This application claims priority based on Japanese Patent Application No. 2021-038057, filed on March 10, 2021, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0076] 10 Sensor device 10A Sensor Device 100 Scanning unit 110 Light source 200 Control section 300 Integrated Circuits 302 Bus 304 Processor 306 Memory 308 Storage Devices 310 Input / Output Interface 312 Network Interface 500A Sensor section L scan line LA 1st Scanning 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] A scanning unit; a control unit that controls a density distribution of the plurality of spots irradiated by the scanning unit until the plurality of spots irradiated by the scanning unit satisfies a first predetermined condition; A sensor device comprising:

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