Control device, optical sensor, control method, and control program

Abstract

A processor of a control device according to the present invention is configured so as to: acquire, in each of detection cycles (Cd) and in relation to individual detection pixels, the light reception intensity with respect to the detection distance; monitor, in each of the detection cycles (Cd), the noise ratio (R) accounted for by the noise pixel number (Nn), which is the number of detection pixels that have detected a noise echo (Ern) identified as a reflected echo from raindrops falling in the outside world, with respect to the corrected pixel number obtained by subtracting, from the total number (ΣN) of detection pixels, the effective pixel number (Nv), which is the number of detection pixels that have detected an effective echo (Erv) identified as a reflected echo from a target; and generate detection data (Dd) for reporting the rainfall state in the outside world in accordance with the noise ratio (R).

Description

Control device, optical sensor, control method, and control program CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2024-12279 filed in Japan on January 30, 2024, and the contents of the original application are incorporated by reference in their entirety.

[0002] The present disclosure relates to techniques for controlling optical sensors.

[0003] Optical sensors that are controlled to receive reflected echoes from targets in response to a projected light beam and output detection data are widely known. For example, Patent Document 1 proposes a technology for detecting rainfall by controlling an optical sensor such as a LiDAR (Light Detection and Ranging) sensor.

[0004] Japanese Patent Application Laid-Open No. 2021-109591

[0005] However, while the technology proposed in Patent Document 1 can determine whether autonomous driving is possible based on the results of rainfall detection that effectively utilizes LiDAR, which detects distance, it does not go so far as to output the detection results themselves as an accurate indicator of rainfall conditions.

[0006] An object of the present disclosure is to provide a control device for effectively utilizing an optical sensor that detects distance to accurately output a rainfall status. Another object of the present disclosure is to provide a control method for effectively utilizing an optical sensor that detects distance to accurately output a rainfall status. Yet another object of the present disclosure is to provide a control program for effectively utilizing an optical sensor that detects distance to accurately output a rainfall status. Yet another object of the present disclosure is to provide an optical sensor that is effectively utilized as an optical sensor that detects distance to accurately output a rainfall status.

[0007] The technical means of the present disclosure for solving the problems will be described below.

[0008] A first aspect of the present disclosure is a control device having a processor for controlling an optical sensor that receives a reflected echo from a target in response to a projected beam of light projected into the outside world in each detection cycle and outputs detection data, wherein the processor is configured to: acquire, in each detection cycle, the received intensity of the reflected echo by the optical sensor in association with each detection pixel of the detection data, with respect to the detection distance to the target according to the timing of receiving the reflected echo by the optical sensor; monitor, in each detection cycle, the noise rate, which is the number of noise pixels that detects a noise echo that is identified as a reflected echo from raindrops that have fallen into the outside world, relative to a corrected pixel number obtained by subtracting the number of valid pixels, which is the number of detection pixels that detects a valid echo that is identified as a reflected echo from the target, from the total number of detection pixels; and generate detection data that notifies the rainfall conditions in the outside world according to the noise rate.

[0009] A second aspect of the present disclosure is a control method executed by a processor to control an optical sensor that receives a reflected echo from a target in response to a projected beam of light projected into the outside world in each detection cycle and outputs detection data, the control method including: acquiring, for each detection cycle, the received intensity of the reflected echo by the optical sensor in association with each detection pixel of the detection data, with respect to the detection distance to the target according to the timing of receiving the reflected echo by the optical sensor; monitoring, for each detection cycle, a noise rate, which is the number of noise pixels that detects a noise echo that is identified as a reflected echo from raindrops that have fallen into the outside world, relative to a corrected pixel number obtained by subtracting the number of valid pixels, which is the number of detection pixels that detects a valid echo that is identified as a reflected echo from the target, from the total number of detection pixels; and generating detection data that notifies the rainfall conditions in the outside world according to the noise rate.

[0010] A third aspect of the present disclosure is a control program stored in a storage medium for controlling an optical sensor that receives a reflected echo from a target in response to a projected light beam projected into the outside world in each detection cycle and outputs detection data, and including instructions for causing a processor to execute the control program, the control program including instructions for causing a processor to execute the following: acquiring, in each detection cycle, the received intensity of the reflected echo by the optical sensor in association with each detection pixel of the detection data, with respect to the detection distance to the target according to the timing of receiving the reflected echo by the optical sensor; monitoring, in each detection cycle, the noise rate, which is the number of detection pixels that detected a noise echo identified as a reflected echo from raindrops that have fallen into the outside world, relative to a corrected pixel number obtained by subtracting the number of valid pixels, which is the number of detection pixels that detected a valid echo identified as a reflected echo from the target, from the total number of detection pixels; and generating detection data that notifies the rainfall conditions in the outside world according to the noise rate.

[0011] In this way, in the first to third aspects, the received light intensity of the reflected echo by the optical sensor is associated with each detection pixel of the detection data and acquired for each detection cycle, with respect to the detection distance to the target according to the timing of receiving the reflected echo by the optical sensor. Therefore, the first to third aspects focus on the corrected pixel number obtained by subtracting the number of valid pixels of detection pixels that detected valid echoes identified as reflected echoes from the target from the total number of detection pixels.

[0012] Specifically, according to the first to third aspects, the noise ratio, which is the number of noise pixels that detect noise echoes identified as reflected echoes from raindrops falling into the outside world, relative to the correction pixel number, which is the number of detection pixels that do not detect reflected echoes from targets, is monitored in each detection cycle. This allows detection data that notifies of rainfall conditions to be generated based on the noise ratio, which has been corrected to account for the influence of the detection of valid echoes from targets and the non-detection of noise echoes from raindrops. Therefore, it is possible to effectively use the optical sensor that detects distance to accurately output rainfall conditions using detection data.

[0013] A fourth aspect of the present disclosure is a control device having a processor for controlling an optical sensor that receives a reflected echo from a target in response to a projected beam of light projected into the outside world in each detection cycle and outputs detection data, wherein the processor is configured to: acquire, in each detection cycle, the received intensity of the reflected echo by the optical sensor in association with each detection pixel of the detection data, with respect to the detection distance to the target according to the timing of receiving the reflected echo by the optical sensor; monitor, in each detection cycle, the ratio of the number of noise echoes identified as reflected echoes from raindrops that have fallen into the outside world to the corrected pixel number obtained by subtracting the number of effective pixels, which is the number of detection pixels that have detected effective echoes identified as reflected echoes from the target, from the total number of detection pixels; and generate detection data that notifies the rainfall conditions in the outside world according to the noise rate.

[0014] A fifth aspect of the present disclosure is a control method executed by a processor to control an optical sensor that receives a reflected echo from a target in response to a projected light beam projected into the outside world in each detection cycle and outputs detection data, the control method including: acquiring, in each detection cycle, the received intensity of the reflected echo by the optical sensor in association with each detection pixel of the detection data, with respect to the detection distance to the target according to the timing of receiving the reflected echo by the optical sensor; monitoring, in each detection cycle, the ratio of the number of noise echoes identified as reflected echoes from raindrops that have fallen into the outside world to a corrected pixel number obtained by subtracting the number of valid pixels, which is the number of detection pixels that have detected valid echoes identified as reflected echoes from the target, from the total number of detection pixels; and generating detection data that notifies the rainfall conditions in the outside world according to the noise rate.

[0015] A sixth aspect of the present disclosure is a control program stored in a storage medium for controlling an optical sensor that receives a reflected echo from a target in response to a projected light beam emitted into the outside world in each detection cycle and outputs detection data, and includes instructions for causing a processor to execute the control program, the control program including instructions for causing a processor to execute the following: acquiring, in each detection cycle, the received intensity of the reflected echo by the optical sensor in association with each detection pixel of the detection data, with respect to the detection distance to the target according to the timing of receiving the reflected echo by the optical sensor; monitoring, in each detection cycle, the ratio of the number of noise echoes identified as reflected echoes from raindrops that have fallen into the outside world to the corrected pixel number obtained by subtracting the number of valid pixels, which is the number of detection pixels that have detected valid echoes identified as reflected echoes from the target, from the total number of detection pixels; and generating detection data that notifies the rainfall conditions in the outside world according to the noise rate.

[0016] In this way, in the fourth to sixth aspects, the received light intensity of the reflected echo by the optical sensor is associated with each detection pixel of the detection data and acquired for each detection cycle, with respect to the detection distance to the target according to the timing of receiving the reflected echo by the optical sensor. Therefore, the fourth to sixth aspects focus on the corrected pixel number obtained by subtracting the number of valid pixels of detection pixels that detected valid echoes identified as reflected echoes from the target from the total number of detection pixels.

[0017] Specifically, according to the fourth to sixth aspects, the ratio of the number of noise echoes identified as reflected echoes from raindrops falling into the outside world to the corrected pixel number, which is the number of detection pixels where reflected echoes from the target were not detected, is monitored in each detection cycle as a noise rate. This allows detection data reporting the rainfall condition to be generated based on the noise rate, which is corrected for the influence of the detection of valid echoes from the target and the non-detection of noise echoes from raindrops. Therefore, it is possible to effectively use the optical sensor that detects distance to accurately output the rainfall condition using the detection data.

[0018] A seventh aspect of the present disclosure is an optical sensor that receives a reflected echo from a target in response to a projected beam projected into the outside world in each detection cycle and outputs detection data, and is configured to include a control device of the first or fourth aspect and is equipped with: a control unit that generates detection data; a light projecting unit that projects the projected beam in accordance with control by the control unit; and a light receiving unit that receives the reflected echo in accordance with control by the control unit.

[0019] The optical sensor of the seventh aspect can achieve the same effects based on the same principle as the control device of the first or fourth aspect.

[0020] FIG. 1 is a cross-sectional view showing the overall configuration of an optical sensor according to a first embodiment; FIG. 2 is a block diagram showing the functional configuration of an optical sensor according to the first embodiment; FIG. 3 is a schematic diagram showing a light projecting light source unit according to the first embodiment; FIG. 4 is a schematic diagram showing a light receiving and detecting unit according to the first embodiment; FIG. 5 is a schematic diagram for explaining detection data according to the first embodiment; FIG. 6 is a flowchart showing a control flow according to the first embodiment; FIG. 7 is a graph showing a control flow according to the first embodiment; FIG. 8 is a graph showing a control flow according to the first embodiment; FIG. 9 is a graph showing a control flow according to the first embodiment; FIG. 10 is a schematic diagram for explaining a control flow according to the first embodiment; FIG. 11 is a flowchart showing a control flow according to a second embodiment; FIG. 12 is a schematic diagram for explaining detection data according to the second embodiment; FIG. 13 is a schematic diagram for explaining the relationship between detection data and a detection field of view according to the second embodiment; FIG. 14 is a flowchart showing a control flow according to a third embodiment; FIG. 15 is a flowchart showing a control subroutine according to the third embodiment; FIG. 16 is a flowchart showing a control flow according to a fourth embodiment; FIG. 17 is a graph showing a control flow according to the fourth embodiment.

[0021] Hereinafter, multiple embodiments of the present disclosure will be described with reference to the drawings. Note that corresponding components in each embodiment are designated by the same reference numerals, and redundant description may be omitted. Furthermore, when only a portion of the configuration is described in each embodiment, the configuration of another previously described embodiment may be applied to the remaining portions of the configuration. Furthermore, in addition to the combinations of configurations explicitly stated in the description of each embodiment, configurations of multiple embodiments may be partially combined together even if not explicitly stated, provided that there is no particular problem with the combination.

[0022] As shown in FIG. 1 , an optical sensor 10 according to a first embodiment of the present disclosure is a LiDAR (Light Detection and Ranging / Laser Imaging Detection and Ranging) sensor that can be mounted on a mobile object 1 and optically detects the external environment of the mobile object 1. The mobile object 1 to which the optical sensor 10 is applied is, for example, an automobile capable of at least one of manual driving, automatic driving, and remote driving. In the following description, unless otherwise specified, the directions indicated as front, rear, up, down, left, and right are defined with respect to the mobile object 1 on a horizontal plane. In the following description, the horizontal direction and the vertical direction refer to the directions parallel to and perpendicular to the horizontal plane, respectively, of the mobile object 1 on the horizontal plane. However, in FIG. 1 , the left side of the dashed-dotted line along the vertical direction (the side of a cover panel 12 described below) actually illustrates a cross section perpendicular to the right side of the dashed-dotted line (the side of components 21 and 41 described below).

[0023] The optical sensor 10 is disposed in at least one location on the mobile body 1, such as the front, left and right side portions, rear portion, or upper roof. As shown in Figures 1 and 2, the optical sensor 10 projects a projected beam Bp toward a detection area Ad in the outside world that corresponds to the location of the optical sensor 10 on the mobile body 1 and the detection field of view. The optical sensor 10 detects, as a reflected echo Er, a beam that is returned when the projected beam Bp is reflected by a target Ot in the detection area Ad in the outside world. The projected beam Bp that becomes the reflected echo Er is selected to be light in the near-infrared range that is difficult for humans to see.

[0024] The optical sensor 10 detects a target Ot present in a detection area Ad of the outside world by receiving a reflected echo Er reflected from the projected beam Bp. Here, the detection of the target Ot involves sensing of multiple types of information, including at least distance and intensity, such as the distance from the optical sensor 10 to the target Ot, the intensity of the reflected echo Er reflected from the target Ot, and the direction in which the target Ot exists.

[0025] The target object Ot that is a typical detection target in the optical sensor 10 applied to the moving body 1 may be at least one of moving objects such as a pedestrian, a cyclist, a non-human animal, another vehicle, etc. The target object Ot that is a typical detection target in the optical sensor 10 applied to the moving body 1 may be at least one of stationary objects such as a guardrail, a road sign, a roadside structure, and an object that has fallen on the road.

[0026] As shown in FIG. 1 , the optical sensor 10 includes a housing 11, a light-projecting unit 21, a scanning unit 31, a light-receiving unit 41, and a control unit 51. The light-shielding housing 11 is formed into a box shape using, for example, metal or resin. The housing 11 houses the light-projecting unit 21, the scanning unit 31, and the light-receiving unit 41 inside. An opening penetrating the housing 11 from the inside to the outside is closed by a cover panel 12. The light-transmitting cover panel 12 is formed using, for example, resin or glass, and separates the inside from the outside of the housing 11. As a result, the outer surface of the cover panel 12 forms a detection surface 12a of the optical sensor 10 that is exposed to the outside world.

[0027] As shown in FIGS. 1 and 2 , the light projecting unit 21 includes a light projecting light source unit 22 and a light projecting lens unit 26. As shown in FIG. 3 , the light projecting light source unit 22 is constructed by mounting a plurality of light source elements 24 in an array on a substrate. The light source elements 24 are laser diodes arranged in a single row (as shown in the example of FIG. 3 ) or in multiple rows (not shown) along the vertical direction. In response to a control signal from the control unit 51, the light source elements 24 generate pulsed laser light that becomes a portion of the projected beam Bp. The light source elements 24 may be edge-emitter lasers or vertical cavity surface-emitting lasers (VCSELs).

[0028] The light projecting light source unit 22 has a light source window 25 formed on one side of the substrate, the light source window 25 being defined as a quasi-rectangular outline with its long sides extending vertically and its short sides extending horizontally. The light source window 25 is configured as a collection of laser oscillation apertures in each light source element 24. The laser light projected from the laser oscillation aperture of each light source element 24 is projected from the light source window 25 as a projecting beam Bp that is simulated to be a line beam extending vertically at least in the external detection area Ad.

[0029] As shown in FIG. 1 , the light-projecting lens unit 26 is constructed in a structure in which at least one light-projecting lens 27 is held in a lens barrel 28. The light-transmitting light-projecting lens 27 is formed mainly from a base material such as resin or glass and has a lens shape corresponding to the optical function to be exerted. The light-projecting lens 27 exerts at least one optical function, such as focusing, collimating, and shaping, on the light-projecting beam Bp from the light-projecting light source unit 22. The light-projecting lens 27 is positioned within a light-blocking lens barrel 28 made of, for example, metal or resin. The light-projecting lens unit 26 configured in this manner is aligned with the light-projecting light source unit 22 to form a light-projecting optical axis that guides the light-projecting beam Bp toward the scanning unit 31.

[0030] 1 and 2, the scanning unit 31 has a scanning mirror 32 and a scanning motor 35. The scanning mirror 32 is constructed in the shape of a plate with a reflective film deposited on a reflective surface 33, which is one side of a base material. The scanning mirror 32 is supported by the housing 11 so as to be rotatable about a rotation center line along the vertical direction. The scanning mirror 32 oscillates within a driving range that is limited by a mechanical or electrical stopper.

[0031] The scanning motor 35 is, for example, a voice coil motor, a brushed DC motor, or a stepping motor. The output shaft of the scanning motor 35 is coupled directly to the scanning mirror 32 or indirectly via a drive mechanism such as a reducer. The scanning motor 35 is held by the housing 11 so as to be able to rotate the scanning mirror 32 together with its output shaft. The scanning motor 35 rotates (i.e., oscillates) the scanning mirror 32 within a limited driving range in accordance with a control signal from the control unit 51.

[0032] The scanning mirror 32 reflects the projected beam Bp incident from the light projecting unit 21 by the reflecting surface 33 and projects it onto the detection area Ad through the cover panel 12, thereby scanning the area Ad in accordance with the rotation angle of the scanning motor 35. At this time, scanning of the detection area Ad by the projected beam Bp is substantially limited to scanning in the horizontal direction in this embodiment, in accordance with the rotational drive of the scanning mirror 32.

[0033] The scanning mirror 32 reflects the reflected echo Er, which is incident from the target Ot in the detection area Ad through the cover panel 12, toward the light receiving unit 41 by the reflecting surface 33 in accordance with the rotation angle of the scanning motor 35. At this time, the speeds of the projected beam Bp and the reflected echo Er are sufficiently greater than the rotational speed of the scanning mirror 32. As a result, the reflected echo Er is reflected by the scanning mirror 32, whose rotation angle with respect to the projected beam Bp can be assumed to be substantially the same, and is guided toward the light receiving unit 41 in the opposite direction to the projected beam Bp.

[0034] The light receiving section 41 includes a light receiving lens unit 42 and a light receiving and detecting unit 45. As shown in FIG. 1 , the light receiving lens unit 42 is constructed such that at least one light receiving lens 43 is held by a lens barrel 44. The light transmitting light receiving lens 43 is formed primarily from a base material such as resin or glass into a lens shape corresponding to the optical function to be exerted. The light receiving lens 43 exerts an optical function to form an image of the reflected echo Er from the scanning mirror 32 on the light receiving and detecting unit 45. The light receiving lens 43 is positioned within the light blocking lens barrel 44, which is formed from, for example, metal or resin. By aligning the light receiving lens unit 42 configured in this manner with the light receiving and detecting unit 45, the light receiving optical axis that guides the reflected echo Er from the scanning section 31 toward the unit 45 is shifted vertically from the light projecting optical axis of the light projecting lens unit 26.

[0035] As shown in FIG. 4 , the light receiving / detecting unit 45 is constructed by mounting a plurality of light receiving pixels 46 in an array on a substrate. The light receiving pixels 46 are arranged at least vertically. The light receiving / detecting unit 45 has a light receiving surface 450 formed on one side of the substrate, the light receiving surface 450 having a rectangular outline with its long sides extending vertically and its short sides extending horizontally. The light receiving surface 450 is configured as a collection of the incident surfaces of the light receiving pixels 46. Each light receiving pixel 46 is composed of a plurality of light receiving elements 460, such as single photon avalanche diodes. Each light receiving pixel 46 receives a reflected echo Er incident on the light receiving surface 450 from the light receiving lens unit 42, as shown in FIG. 1 .

[0036] 1 and 2, the light receiving and detecting unit 45 is provided with an output circuit 47. The output circuit 47 performs sampling processing for each scanning line in accordance with the rotation angle of the scanning mirror 32, which is synchronized with the timing of projection of the light projecting beam Bp from the light projecting light source unit 22, for each detection cycle Cd (see FIG. 5 described later) in accordance with a control signal from the control unit 51. At this time, the output circuit 47 generates a detection signal by combining response outputs from the light receiving elements 460 of each light receiving pixel 46 for each detection cycle Cd. The detection signals generated in this manner are output from the output circuit 47 to the control unit 51 for each scanning line.

[0037] The control unit 51 is configured as a control device including at least one dedicated computer mounted on a circuit board. The dedicated computer constituting the control device as the control unit 51 may be a sensor ECU (Electronic Control Unit) specialized for controlling the optical sensor 10, in which case the sensor ECU is housed in the housing unit 11 (example of FIG. 1). The dedicated computer constituting the control device as the control unit 51 may be a driving control ECU specialized for controlling the driving of the mobile object 1, in which case the driving control ECU is located outside the housing unit 11 in the mobile object 1 (not shown).

[0038] 1, the dedicated computer constituting the control device as the control unit 51 has at least one memory 51a and one processor 51b. The memory 51a is at least one type of non-transitory tangible storage medium, such as a semiconductor memory, a magnetic medium, or an optical medium, that non-temporarily stores computer-readable programs and data. The processor 51b includes at least one type of core, such as a central processing unit (CPU), a graphics processing unit (GPU), a reduced instruction set computer (RISC)-CPU, a data flow processor (DFP), or a graph streaming processor (GSP).

[0039] The control unit 51 configured as above is connected to the light projecting light source unit 22, the scanning motor 35, and the light receiving and detecting unit 45. The control unit 51 controls the light projecting light source unit 22 so as to generate the light projecting beam Bp for each detection cycle Cd. At the same time, the control unit 51 controls the scanning motor 35 so as to control, for each detection cycle Cd, the scanning and reflection by the scanning mirror 32 synchronized with the light projection timing by the light projecting light source unit 22. Furthermore, the control unit 51 processes, for each detection cycle Cd, the detection signal output from the output circuit 47 of the light receiving and detecting unit 45, which is controlled in accordance with the light projection by the light projecting light source unit 22 and the scanning and reflection by the scanning mirror 32.

[0040] 5 to represent the detected distance L to the target Ot in the detection area Ad and the received light intensity I of the reflected echo Er from the target Ot (see FIGS. 7 to 10 described later for both L and I) for each detection cycle Cd, and output the detection data Dd to the moving body 1. In this case, even if the detected distance L and received light intensity I are physically detected by the same light-receiving pixel 46, the detected data Dd is reflected as data values ​​associated with different detection pixels 46a between different scanning lines α within the detection cycle Cd as shown in FIG.

[0041] To specifically realize such control, the processor 51b executes a plurality of instructions included in a control program stored in the memory 51a, causing the control unit 51 to construct a plurality of functional blocks for controlling the optical sensor 10. The functional blocks thus constructed by the control unit 51 include a detection block 100, a monitoring block 110, and a data generation block 120, as shown in FIG.

[0042] The control method in which the control unit 51 controls the optical sensor 10 through cooperation of these blocks 100, 110, and 120 is executed according to the control flow shown in Fig. 6. This control flow is repeatedly executed for each detection cycle Cd during the startup of the mobile object 1. Note that each "S" in the control flow represents a plurality of steps executed by a plurality of commands included in the control program.

[0043] In S100, the detection block 100 acquires the detection signals for each scanning line α in the current detection cycle Cd from the output circuit 47. In the following S110, the detection block 100 generates light reception data Dr (see FIG. 5) for all detection pixels 46 a in the light reception detection unit 45 based on the detection signals for each scanning line α acquired in the current detection cycle Cd.

[0044] Specifically, in S110, a detected distance L to the target Ot is acquired based on the elapsed time from the time when the light projecting light beam Bp is projected by the light projecting light source unit 22 to the time when the light is received by the light receiving / detecting unit 45 at the peak of the reflected echo Er. The acquired detected distance L is associated with each detection pixel 46a as a data value of the light receiving data Dr used to generate the detection data Dd (described later) in accordance with the detection data Dd. At the same time, in S110, the light receiving intensity I at the peak of the reflected echo Er by the light receiving / detecting unit 45 is also acquired and associated with each detection pixel 46a as a data value of the light receiving data Dr. At this time, the light receiving intensity I of the reflected echo Er may be corrected by subtracting the intensity of background light estimated based on the light receiving intensity I associated with a detection pixel 46a that does not detect the peak of the reflected echo Er, for example. As a result, the detected distance L and the light receiving intensity I are also associated with each detection pixel 46a in the light receiving data Dr.

[0045] In the next step S120, the monitoring block 110 identifies the type of reflected echo Er detected for each detection pixel 46a from the received light data Dr generated for the current detection cycle Cd. The identified types of reflected echo Er include noise echo Ern and valid echo Erv, as shown in Figures 7 to 9. Therefore, a noise range LIn and a valid range LIv are defined to identify the noise echo Ern and valid echo Erv, respectively.

[0046] Specifically, the noise range LIn and the effective range LIv are defined with a threshold intensity It corresponding to the detection distance L as the upper and lower boundaries, respectively, for the received light intensity I, as shown in Figures 7 to 10. The threshold intensity It is set to monotonically decrease as the detection distance L increases. It is preferable that the rate of decrease of the threshold intensity It per unit distance gradually decreases as the detection distance L increases, as shown in Figures 7 to 10.

[0047] 7 to 10, the noise range LIn and the effective range LIv are further defined as ranges equal to or greater than a near threshold distance Lt1 and equal to or less than a far threshold distance Lt2 with respect to the detection distance L. The near threshold distance Lt1 is set in a range exceeding zero, for example, to correspond to the position of the detection surface 12a in the optical sensor 10, such as the distance between the detection surface 12a and the light-receiving surface 450. The far threshold distance Lt2 is set to correspond to the detection limit distance of the optical sensor 10, such as the distance between the far point of the depth of field provided by the light-receiving lens unit 42 and the detection surface 12a.

[0048] With these definitions and settings, the noise range LIn becomes a condition range for identifying a noise echo Ern where the received light intensity I is equal to or less than the upper boundary threshold intensity It, as shown in Figures 7 and 8, from a reflected echo Er at a detection distance L that is equal to or greater than the near threshold distance Lt1 and equal to or less than the far threshold distance Lt2. As a result, even if the received light intensity I of the reflected echo Er is equal to or less than the threshold intensity It, a reflected echo Er at a detection distance L that is less than the near threshold distance Lt1 or exceeds the far threshold distance Lt2 is excluded from the identification of the noise echo Ern. On the other hand, the effective range LIv becomes a condition range for identifying a valid echo Erv where the received light intensity I exceeds the lower boundary threshold intensity It, as shown in Figure 9, from a reflected echo Er at a detection distance L that is equal to or greater than the near threshold distance Lt1 and equal to or less than the far threshold distance Lt2. As a result, even if the received light intensity I of the reflected echo Er exceeds the threshold intensity It, the reflected echo Er at the detection distance L that is less than the near threshold distance Lt1 or exceeds the far threshold distance Lt2 is excluded from the identification of the valid echo Erv.

[0049] 7 to 10, the near threshold distance Lt1 is set to a common value for the noise range LIn and the effective range LIv, but may be set to different values ​​for the noise range LIn and the effective range LIv. In the examples of FIGS. 7 to 10, the far threshold distance Lt2 is set to a common value for the noise range LIn and the effective range LIv, but may be set to different values ​​for the noise range LIn and the effective range LIv. With respect to the received light intensity I, a noise range LIn less than a threshold intensity It and an effective range LIv equal to or greater than the threshold intensity It may be adopted for a detection distance L equal to or greater than the near threshold distance Lt1 and equal to or less than the far threshold distance Lt2.

[0050] In S120 of FIG. 6 , a reflected echo Er associated with a detection distance L and a light-receiving intensity I within the noise range LIn for each detection pixel 46a is identified as a noise echo Ern. In this first embodiment, among the reflected echoes Er for which the light-receiving timing for each detection pixel 46a is the earliest in the current detection cycle Cd, the noise echo Ern is identified by limiting the reflected echoes Er for which the detection distance L and the light-receiving intensity I are within the noise range LIn, as shown in FIGS. 7 and 8 . The earliest light-receiving timing here is equivalent to the detection distance L that provides the light-receiving intensity I for each detection pixel 46a within the noise range LIn being the shortest in the current detection cycle Cd. The noise echo Ern thus identified is defined as a reflected echo Er from raindrops falling into the outside world, distinct from the reflected echo Er from the target Ot that is the intended detection target.

[0051] Meanwhile, in S120, the reflected echo Er associated with the detection distance L and the received light intensity I within the effective range LIv for each detection pixel 46a is identified as a valid echo Erv. In this first embodiment, among the reflected echoes Er for which the detection distance L and the received light intensity I are the earliest in the current detection cycle Cd for each detection pixel 46a, the valid echo Erv is identified by limiting the reflected echoes Er to those whose detection distance L and the received light intensity I are within the effective range LIv, as shown in FIG. 9 . Here, the earliest light reception timing is equivalent to the detection distance L that provides the received light intensity I within the effective range LIv for each detection pixel 46a being the shortest in the current detection cycle Cd. The valid echo Erv identified in this way is defined as the reflected echo Er from the target Ot, excluding raindrops.

[0052] As shown in FIG. 6 , in the next step S130, the monitoring block 110 extracts the number of noise pixels shown in FIG. 11 as the detection pixels 46 a for which a noise echo Ern was identified in S120 for the current detection cycle Cd. That is, in S130 in FIG. 6 , the number of noise pixels Nn, which is the number of noise pixels that detected the noise echo Ern in the current detection cycle Cd, is counted. At the same time, in S130, the monitoring block 110 extracts the number of valid pixels shown in FIG. 11 as the detection pixels 46 a for which a valid echo Erv was identified in S120 for the current detection cycle Cd. That is, in S130 in FIG. 6 , the number of valid pixels Nv, which is the number of valid pixels that detected the valid echo Erv in the current detection cycle Cd, is also counted.

[0053] As shown in FIG. 6 , in the next step S140, the monitoring block 110 monitors the noise rate R, which correlates with the number of noise pixels Nn and the number of valid pixels Nv counted in step S130 for the current detection cycle Cd. The noise rate R is defined as the ratio of the number of noise pixels Nn to the corrected number of pixels obtained by subtracting the number of valid pixels Nv from the total number of detection pixels 46a, according to the following equation (1): Here, particularly in the first embodiment in which the noise echo Ern is limited to the earliest reflected echo Er as described above, the number of noise pixels Nn and the number of noise echoes Ern are substantially equal. As a result, the noise rate R in the first embodiment is also equivalent to the ratio of the number of noise echoes Ern to the corrected number of pixels obtained by subtracting the number of valid pixels Nv from the total number of detection pixels 46a.

[0054] In this case, the monitoring in S140 may be limited to the values ​​for the current detection cycle Cd for the number of noise pixels Nn and the number of valid pixels Nv. In the monitoring in S140, the number of noise pixels Nn and the number of valid pixels Nv may be each calculated by integrating and averaging the values ​​for a set number of previous detection cycles Cd in addition to the value for the current detection cycle Cd. Here, when the latter average value is used, the set number of previous cycles to be added to the current cycle may be preset to, for example, the most recent nine cycles so that a total of 10 values ​​for the current and previous cycles are averaged.

[0055] As shown in FIG. 6 , in subsequent S150, the data generation block 120 generates detection data Dd, which includes the light reception data Dr for all detection pixels 46 a and is output to the mobile object 1 to notify the external rainfall condition in accordance with the noise rate R monitored in S140. In this case, the rainfall condition may be output by the detection data Dd as diagnostic information notifying the amount of rainfall Q per set time, which is defined according to the following equation 2 using a monomial or polynomial function F as a physical quantity correlated with the noise rate R. The rainfall condition may also be output by the detection data Dd as warning information notifying heavy rainfall in response to the noise rate R rising to a warning range that is equal to or exceeds the noise threshold. Here, the warning range may be preset to a range of the noise rate R corresponding to the amount of rain that requires a warning to the mobile object 1 equipped with the optical sensor 10.

[0056] In this way, when the current execution of the control flow in the current detection cycle Cd is completed upon completion of execution of S150 during the start of the moving body 1, the next execution of the control flow in the next detection cycle Cd is started.

[0057] (Operations and Effects) Operations and effects of the first embodiment described above will be described below.

[0058] In the first embodiment, the received light intensity I of the reflected echo Er by the optical sensor 10 is associated with each detection pixel 46a in the detection data Dd and acquired for each detection cycle Cd, with respect to the detection distance L to the target Ot corresponding to the timing of receiving the reflected echo Er by the optical sensor 10. Therefore, the first embodiment focuses on the corrected pixel number obtained by subtracting the number Nv of valid pixels of the detection pixels 46a that detected a valid echo Erv identified as the reflected echo Er from the target Ot from the total number ΣN of the detection pixels 46a.

[0059] Specifically, in the first embodiment, the noise ratio R, which is the number of noise pixels Nn that detect noise echoes Ern identified as reflected echoes Er from raindrops falling into the outside world, relative to the corrected pixel number, which is the number of detection pixels 46a that did not detect the reflected echo Er from the target Ot, is monitored for each detection cycle Cd. Here, the noise ratio R in the first embodiment can also be considered as the ratio of the number of noise echoes Ern to the corrected pixel number. This monitoring allows detection data Dd reporting the rainfall condition to be generated based on the noise ratio R, which is corrected for the influence of the detection of valid echoes Erv from the target Ot that prevent the noise echo Ern from raindrops from being detected. Therefore, the optical sensor 10 that detects the distance L can be effectively used to accurately output the rainfall condition using the detection data Dd.

[0060] According to the first embodiment, within the noise range LIn, which has an upper boundary of the threshold intensity It for the received light intensity I, which decreases as the detection distance L increases, the reflected echo Er associated with the detection distance L and the received light intensity I for each detection pixel 46a is identified as a noise echo Ern. This makes it possible to accurately distinguish noise echoes Ern from raindrops that have fallen into the outside world from the reflected echoes Er for each detection pixel 46a. On the other hand, within the effective range LIv, which has a lower boundary of the threshold intensity It for the received light intensity I, the reflected echo Er associated with the detection distance L and the received light intensity I for each detection pixel 46a is identified as a valid echo Erv. This makes it possible to accurately distinguish valid echoes Erv from the target Ot from the reflected echoes Er for each detection pixel 46a. From these findings, by monitoring the noise rate R, which can reflect the results of accurately identifying the noise echo Ern and valid echo Erv, it is possible to improve the output accuracy of the rainfall status according to the noise rate R.

[0061] According to the first embodiment, among the reflected echoes Er that are received earliest in each detection cycle Cd for each detection pixel 46a, those whose detection distance L and received light intensity I are within the noise range LIn are identified as noise echoes Ern. On the other hand, among the reflected echoes Er that are received earliest in each detection cycle Cd for each detection pixel 46a, those whose detection distance L and received light intensity I are within the effective range LIv are identified as effective echoes Erv. By identifying the noise echoes Ern and effective echoes Erv, it becomes possible to speed up the processor 51b's determination of the number of noise pixels Nn and the number of effective pixels Nv corresponding to each echo, thereby shortening the time required to generate detection data Dd for outputting the rainfall status according to the noise rate R.

[0062] According to the first embodiment, among the reflected echoes Er whose detection distance L and received light intensity I are within the noise range LIn, the noise echo Ern is identified by limiting it to the reflected echo Er that is received earliest in each detection cycle Cd for each detection pixel 46a. This can speed up the processing by the processor 51b from identifying the noise echo Ern to determining the number of noise pixels Nn, thereby making it possible to effectively reduce the time required to generate detection data Dd for outputting the rainfall condition according to the noise rate R.

[0063] According to the first embodiment, the noise echo Ern and the valid echo Erv are determined from the reflected echo Er at a detection distance L equal to or greater than the near threshold distance Lt1 corresponding to the position of the detection surface 12a exposed to the outside world in the optical sensor 10. In contrast, the reflected echo Er at a detection distance L less than the near threshold distance Lt1 is excluded from the determination of the noise echo Ern and the valid echo Erv. This allows the noise echo Ern and the valid echo Erv to be accurately determined while excluding the reflected echo Er caused by factors other than raindrops, such as obstructions or dirt on the detection surface 12a. Therefore, by monitoring the noise rate R, which can reflect such accurate determination results, the output accuracy of the rainfall condition corresponding to the noise rate R can be improved.

[0064] According to the first embodiment, the detection data Dd may be generated so as to report the rainfall state based on the rainfall amount Q that correlates with the noise rate R. In this case, the rainfall state can be output more precisely using the index of the rainfall amount Q.

[0065] According to the first embodiment, the detection data Dd may be generated to notify the mobile body 1 on which the optical sensor 10 is mounted of a rainfall state in response to the noise rate R increasing to a warning range that warns the mobile body 1. In this case, the optical sensor 10 can be effectively used not only to accurately output the rainfall state according to the noise rate R within the warning range, but also to ensure the safety of the mobile body 1 during movement.

[0066] Second Embodiment The second embodiment is a modification of the first embodiment. As shown in FIG. 12 , in the control flow of the second embodiment, steps S2130, S2140, and S2150, which replace steps S130, S140, and S150, respectively, of the first embodiment, are executed individually for a plurality of pixel areas 46 b. Here, each pixel area 46 b is defined to include a set number of detection pixels 46 a, as shown by the dot hatching of different coarseness in FIG. 13 , and corresponds to each of the division sections Vdb obtained by dividing the entire detection field Vd of all the scanning lines α of the optical sensor 10, as shown in FIG. 14 .

[0067] Specifically, in S2130, the monitoring block 110 counts the numbers of pixels Nn and Nv for each pixel area 46b. Then, in S2140, the monitoring block 110 monitors the noise rate R for each pixel area 46b. Furthermore, in S2150, the data generation block 120 generates detection data Dd that includes the light reception data Dr for all detection pixels 46a and indicates the rainfall state for each pixel area 46b according to the noise rate R. Thus, while the vehicle 1 is running, when the current execution of the control flow for the current detection cycle Cd ends upon completion of execution of S2150, the next execution of the control flow for the next detection cycle Cd begins.

[0068] According to the second embodiment, the noise rate R is monitored for each pixel area 46b defined by including a set number of detection pixels 46a, and therefore the rainfall condition for each division Vdb corresponding to each pixel area 46b in the detection field of view Vd can be output as detection data Dd. This makes it possible to precisely notify the rainfall condition for each division Vdb even for a relatively wide detection field of view Vd.

[0069] Third Embodiment The third embodiment is a modification of the first embodiment. As shown in Fig. 15, in the control flow of the third embodiment, S3140 is executed instead of S140 and S150 of the first embodiment.

[0070] Specifically, in S3140, the control subroutine shown in Fig. 16 is executed. In S3141 of this control subroutine, the monitoring block 110 extracts the value of the number of valid pixels Nv by averaging the values ​​counted in S130 for the current detection cycle Cd plus the values ​​counted in S130 for a set number of previous detection cycles Cd. Here, the set number of previous cycles to be added to the current cycle in extracting the number of valid pixels Nv may be preset to, for example, the most recent nine cycles so that a total of 10 values ​​for the current and previous cycles are averaged.

[0071] In S3141, the monitoring block 110 determines whether the average value of the number of valid pixels Nv for the current and previous measurements has fallen to within a monitoring range where the average value is equal to or less than the first valid threshold. The monitoring range is preferably preset to a range of the number of valid pixels Nv where monitoring of the noise rate R is required as a rainfall state in which the number of valid pixels Nv decreases. If a positive determination is made in S3141, the control subroutine proceeds to S3142.

[0072] In S3142, the monitoring block 110 monitors the noise rate R, which correlates with the number of noise pixels Nn and the number of valid pixels Nv, according to equation (1) in the first embodiment. That is, in S3142, the noise rate R, which correlates with the number of valid pixels Nv when it has fallen within the monitoring range, is monitored. However, as in S3141, the average value is used as the value of the number of valid pixels Nv. Meanwhile, the value of the number of noise pixels Nn is calculated by integrating and averaging the values ​​counted in S130 for the current detection cycle Cd and the values ​​counted in S130 for a set number of past detection cycles Cd. Here, the set number of past cycles to be added to the current cycle when extracting the number of noise pixels Nn may be preset to, for example, the most recent nine cycles, so that a total of 10 values ​​for the current and past cycles are averaged.

[0073] In S3142, the monitoring block 110 determines whether the noise rate R monitored based on the average values ​​of the pixel counts Nn and Nv for the current and previous measurements has risen to within a warning range where the noise rate R is equal to or exceeds the first noise threshold. The warning range may be preset to a range of noise rate R corresponding to the amount of rainfall that requires a warning to the mobile object 1 equipped with the optical sensor 10. If a positive determination is made in S3142, the control subroutine proceeds to S3143.

[0074] In S3143, the data generation block 120 generates detection data Dd that includes the light reception data Dr for all detection pixels 46a and that notifies the external rainfall state in accordance with the noise rate R monitored in S3142. At this time, the rainfall state is output by the detection data Dd as warning information notifying heavy rainfall in response to the noise rate R rising to a warning range that is equal to or exceeds the first noise threshold.

[0075] If a negative determination is made in S3142, the control subroutine proceeds to S3144. In S3144, the monitoring block 110 determines whether the noise rate R, which is monitored based on the average values ​​of the pixel counts Nn and Nv for the current and previous measurements, has decreased to within a cancellation rate range that is less than or equal to the second noise threshold, as in S3142. The cancellation rate range is a range of the noise rate R corresponding to the amount of rainfall within which the warning for the mobile object 1 can be cancelled, and is preferably preset to a range of the noise rate R smaller than the warning range.

[0076] If a negative determination is made in S3141, the control subroutine proceeds to S3145. In S3145, the monitoring block 110 determines whether the average value of the number of valid pixels Nv for the current and previous times, extracted in the same manner as in S3141, has risen to within the range of the number of valid pixels Nv that is equal to or exceeds the second valid threshold. The range of the number of valid pixels Nv to be released is a range of the number of valid pixels Nv corresponding to the amount of rainfall that allows the release of the warning for the mobile object 1, and is preferably preset to a range of the number of valid pixels Nv that is greater than the monitoring range.

[0077] If a positive determination is made in either S3144 or S4145, the control subroutine proceeds to S3146. In S3146, the data generation block 120 generates detection data Dd, which includes the light reception data Dr for all detection pixels 46a and is output to cancel the rain notification.

[0078] On the other hand, if a negative determination is made in either S3144 or S4145, the control subroutine proceeds to S3147. In S3147, the data generation block 120 generates detection data Dd that includes the light reception data Dr for all detection pixels 46a and that is output so as to inherit the rainfall condition notification or cancellation determination result made in either S3143, S3146, or S3147 in the previous detection cycle Cd. Here, the rainfall condition determination result made in the previous detection cycle Cd, particularly in S3147, inherits the rainfall condition notification or cancellation determination result made in the detection cycle Cd two cycles ago in which S3143 or S3146 was last executed.

[0079] Thus, while the moving body 1 is in operation, when the current execution of the control flow and control subroutine in the current detection cycle Cd ends upon completion of execution of any of S3143, S3146, and S3147, the next execution of the control flow in the next detection cycle Cd will begin.

[0080] According to the third embodiment described above, the detection data Dd is generated so as to notify the rainfall state in response to the noise rate R increasing to within a warning range for warning the mobile body 1 equipped with the optical sensor 10. This makes it possible to effectively utilize the optical sensor 10 not only to accurately output the rainfall state according to the noise rate R within the warning range, but also to ensure the safety of the mobile body 1 during movement.

[0081] Furthermore, according to the third embodiment, the noise rate R, which correlates with the number of valid pixels Nv (specifically, its average value) when the number of valid pixels Nv falls within the monitoring range, is monitored. This allows the number of noise pixels Nn corresponding to rainfall to be estimated to be falling while the number of valid pixels Nv is high outside the monitoring range. Therefore, the noise rate R can be immediately determined to be outside the warning range without monitoring. Therefore, it is possible to shorten the time required to generate the detection data Dd in cases where it is essentially unnecessary to determine the rainfall state according to the noise rate R.

[0082] 17, in the control flow of the fourth embodiment, steps S4120, S4130, S4140, and S4150 are executed instead of steps S120, S130, S140, and S150 of the first embodiment, respectively.

[0083] Specifically, in S4120, the monitoring block 110 identifies, as noise echoes Er, all reflected echoes Er detected in the current detection cycle Cd whose detection distance L and received light intensity I are within the noise range LIn for each detection pixel 46a and whose detection cycle Cd is the same for each detection pixel 46a, as noise echoes Er. That is, if the received light intensity I is within the noise range LIn, not only the reflected echo Er whose light reception timing is the earliest for each detection pixel 46a in the current detection cycle Cd, but also the reflected echoes Er whose light reception timing is second or later for each detection pixel 46a in the current detection cycle Cd are identified as different noise echoes Er. Here, being the second or later reflected echo is equivalent to the detection distance L that gives the received light intensity I for each detection pixel 46a within the noise range LIn being the second or later shortest in the current detection cycle Cd. However, the identification of valid echoes Erv in S4120 is performed in accordance with S120 of the first embodiment.

[0084] In the fourth embodiment, in the next step S4130, the monitoring block 110 counts the sum of the respective specific numbers of noise echoes Ern at the detection pixels 46a that have detected at least one noise echo Ern in the current detection cycle Cd as the specific noise number Nne instead of the noise pixel number Nn, as shown in Fig. 17. However, the counting of the number of valid pixels Nv in step S4130 is performed in accordance with step S130 in the first embodiment.

[0085] Next, in S4140, the monitoring block 110 monitors the noise rate R, which correlates with the noise specific number Nne and the number of valid pixels Nv counted in S4130 for the current detection cycle Cd. At this time, the noise rate R is defined as the ratio of the noise specific number Nne to the corrected number of pixels obtained by subtracting the number of valid pixels Nv from the total number ΣN of detection pixels 46a, according to the following equation 3:

[0086] Further, in S4150, the data generation block 120 generates detection data Dd that includes the light reception data Dr for all detection pixels 46a and reports the external rainfall condition according to the noise rate R monitored in S4140. At this time, the rainfall condition may be output by the detection data Dd as diagnostic information reporting the amount of rainfall Q per set time, which is defined according to the following equation 4 using a monomial or polynomial function G different from equation 2 in the first embodiment as a physical quantity correlated with the noise rate R. However, similar to S150 in the first embodiment, the rainfall condition may also be output as warning information reporting heavy rainfall.

[0087] In this way, when the current execution of the control flow in the current detection cycle Cd is completed upon completion of execution of S4150 during the start of the moving body 1, the next execution of the control flow in the next detection cycle Cd will be started.

[0088] Thus, the fourth embodiment also focuses on the corrected pixel number obtained by subtracting the number of valid pixels Nv of the detection pixels 46a that detected valid echoes Erv identified as reflected echoes Er from the target Ot from the total number of detection pixels 46a ΣN. However, according to the fourth embodiment, the ratio of the noise identification number Nne, which is the number of noise echoes Ern identified as reflected echoes Er from raindrops falling into the outside world, to the corrected pixel number, which is the number of detection pixels 46a that did not detect the reflected echo Er from the target Ot, is monitored as the noise rate R for each detection cycle Cd. This allows detection data Dd reporting the rainfall condition to be generated based on the noise rate R, which has been corrected to account for the influence of the detection of valid echoes Erv from the target Ot and the non-detection of noise echoes Ern from raindrops. Therefore, the optical sensor 10 that detects the distance L can be effectively used to accurately output the rainfall condition using the detection data Dd.

[0089] Furthermore, according to the fourth embodiment, among the reflected echoes Er whose detection distance L and received light intensity I are within the noise range LIn, all reflected echoes Er detected for each detection pixel 46a in the same detection cycle Cd are identified as noise echoes Ern. This allows all noise echoes Ern reflected by raindrops whose detection distance L from the optical sensor 10 is different to be identified for each detection pixel 46a and each detection cycle Cd and reflected in the noise rate R, thereby improving the output accuracy of the rainfall condition according to the noise rate R.

[0090] (Other Embodiments) Although multiple embodiments have been described above, the present disclosure should not be construed as being limited to those embodiments, and can be applied to various embodiments and combinations within the scope that does not deviate from the gist of the present disclosure.

[0091] In a modified example, the dedicated computer constituting the control device as the control unit 51 may have at least one of a digital circuit and an analog circuit as a processor. Here, the digital circuit is at least one of an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a system on a chip (SOC), a programmable gate array (PGA), and a complex programmable logic device (CPLD). Such a digital circuit may also have a memory that stores a program.

[0092] In the modified examples of S150, S2150, S3143, S3146, S3147, and S4150, the detection data Dd relating to the rainfall state may be generated independently of the detection data Dd including the light reception data Dr for all the detection pixels 46 a. In this case, the generation of the separate detection data Dd including the light reception data Dr for all the detection pixels 46 a may be performed by the data generation block 120 in S150, S2150, S3143, S3146, S3147, and S4150, or may be performed by the detection block 100 or the data generation block 120 prior to S110.

[0093] In a modified example, the process of identifying the total reflection echo Er within the noise range LIn as the noise echo Ern in S4120 of the fourth embodiment may be executed instead of the process of identifying the earliest reflection echo Er within the noise range LIn as the noise echo Ern in S120 of the first to third embodiments. In this case, in S130 and S2130 of the first to third embodiments, the number of noise pixels Nn, which is the number of detection pixels 46a that detected at least one noise echo Ern in the current detection cycle Cd, may be counted.

[0094] In a modified example, a process for identifying a total reflected echo Er within the effective range LIv as a valid echo Erv in accordance with S4120 of the fourth embodiment may be executed instead of the process for identifying the earliest reflected echo Er within the effective range LIv as a valid echo Erv by S120 and S4120 of the first to fourth embodiments. In this case, the number of valid pixels Nv, which is the number of detection pixels 46a that detected at least one valid echo Erv in the current detection cycle Cd, may be counted in S130, S2130, and S4130 of the first to fourth embodiments.

[0095] In a modified example, the execution for each pixel area 46b according to the second embodiment may be applied to the execution of S130 and S3140 according to the third embodiment. In a modified example, the execution for each pixel area 46b according to the second embodiment may be applied to the execution of S4130, S4140, and S4150 according to the fourth embodiment. In a modified example, the detection data Dd that notifies the amount of rainfall Q according to Equation 2 in S150 of the first embodiment may be executed instead of or in addition to the detection data Dd that notifies the amount of heavy rainfall in response to an increase in the noise rate R into the warning range in S3143 of S3140 of the third embodiment. In a modified example, at least one of the ranges LIn and LIv may be defined as a range of the detection distance L equal to or greater than zero, without setting the near threshold Lt1.

[0096] In a modified example, the identification of the noise echo Ern by S4120 of the fourth embodiment may be executed instead of the identification of the noise echo Ern by S120 of the third embodiment. In this case, the counting of the noise identification number Nne by S4130 of the fourth embodiment may be executed instead of the counting of the noise pixel number Nn by S130 of the third embodiment. At the same time, the monitoring of the noise rate R correlated with the noise identification number Nne by S4140 of the fourth embodiment may be executed instead of the monitoring of the noise rate R correlated with the noise pixel number Nn by S3142 of S3140 of the third embodiment. Furthermore, in this case, the detection data Dd reporting the rainfall amount Q according to Equation 4 by S4150 of the fourth embodiment may be executed instead of or in addition to the detection data Dd reporting the heavy rainfall amount in response to the increase in the noise rate R into the warning range by S3143 of S3140 of the third embodiment.

[0097] In a modified example, the mobile body 1 to which the control device that executes the above-described control method and control program as the control unit 51 and the optical sensor 10 that includes the same are applied may be, for example, an autonomous robot that is capable of transporting luggage or collecting information by autonomous or remote driving. In a modified example, the control device that executes the above-described control method and control program as the control unit 51 and the optical sensor 10 that includes the same may be applied to infrastructure equipment such as smart poles in addition to the mobile body 1. In addition to the forms described so far, the above-described embodiments and modified examples may be implemented with the control device as the control unit 51 in the form of a semiconductor device (for example, a semiconductor chip).

[0098] (Additional Remarks) This specification discloses the following technical ideas and their combinations. Note that the reference symbols in parentheses in this Additional Remarks section indicate the correspondence with the specific means described in the above detailed embodiments, and do not limit the technical scope of the present disclosure.

[0099] (Technical Idea 1) A control device having a processor (51b) for controlling an optical sensor (10) that receives a reflected echo (Er) from a target (Ot) in response to a projected beam (Bp) projected to the outside world for each detection cycle (Cd) and outputs detection data (Dd), wherein the processor: acquires, for each detection cycle, a light intensity (I) of the reflected echo by the optical sensor associated with each detection pixel (46a) of the detection data, for a detection distance (L) to the target according to a timing of receiving the reflected echo by the optical sensor; and monitors, for each detection cycle, a noise rate (R) of a noise pixel number (Nn), which is the number of detection pixels that detected a noise echo (Ern), which is the number of detection pixels that detected a noise echo (Ern), which is the number of reflection echoes from raindrops that fell into the outside world, relative to a corrected pixel number obtained by subtracting a valid pixel number (Nv), which is the number of detection pixels that detected a valid echo (Erv), which is identified as the reflection echo from the target, from a total number (ΣN) of the detection pixels; generating the detection data indicative of the external rainfall state in accordance with the noise rate.

[0100] (Technical Idea 2) A control device having a processor (51b) for controlling an optical sensor (10) that receives a reflected echo (Er) from a target (Ot) in response to a projected beam (Bp) projected to the outside world for each detection cycle (Cd) and outputs detection data (Dd), wherein the processor: acquires, for each detection cycle, a received light intensity (I) of the reflected echo by the optical sensor in association with each detection pixel (46a) of the detection data, for a detection distance (L) to the target according to a timing of receiving the reflected echo by the optical sensor; and monitors, for each detection cycle, a noise rate (R) as a ratio of the number of noise echoes (Ern) identified as the reflected echo from raindrops that have fallen into the outside world to a corrected pixel number obtained by subtracting a valid pixel number (Nv), which is the number of detection pixels that have detected a valid echo (Erv) identified as the reflected echo from the target, from a total number of detection pixels (ΣN). generating the detection data indicative of the external rainfall state in accordance with the noise rate.

[0101] (Technical Idea 3) A control device according to Technical Idea 1 or 2, wherein monitoring the noise rate includes: identifying the reflected echo associated with the detection distance and the received light intensity for each detection pixel as the noise echo within a noise range (LIn) having an upper boundary defined by a threshold intensity (It) for the received light intensity, which decreases as the detection distance increases; and identifying the reflected echo associated with the detection distance and the received light intensity for each detection pixel as the effective echo within an effective range (LIv) having a lower boundary defined by the threshold intensity for the received light intensity.

[0102] (Technical Idea 4) A control device according to Technical Idea 3, wherein monitoring the noise rate includes: identifying, as noise echoes, the reflected echoes whose detection distance and light receiving intensity are within the noise range among the reflected echoes whose light receiving timing is the earliest in each detection cycle for each detection pixel; and identifying, as effective echoes, the reflected echoes whose detection distance and light receiving intensity are within the effective range among the reflected echoes whose light receiving timing is the earliest in each detection cycle for each detection pixel.

[0103] (Technical Idea 5) A control device according to Technical Idea 4, in which monitoring the noise rate includes identifying the noise echo by limiting it to the reflected echo whose detection distance and received light intensity are within the noise range and whose received light timing is the earliest in each detection cycle for each detection pixel.

[0104] (Technical Idea 6) A control device according to Technical Idea 4, wherein monitoring the noise rate includes identifying all reflected echoes detected in the same detection cycle for each detection pixel, among the reflected echoes whose detection distance and received light intensity are within the noise range, as noise echoes.

[0105] (Technical Idea 7) A control device according to any one of Technical Ideas 3 to 6, wherein monitoring the noise rate includes: identifying the noise echoes and the effective echoes from the reflected echoes at the detection distance that is equal to or greater than a threshold distance (Lt1) corresponding to the position of the detection surface (12a) exposed to the outside world in the optical sensor; and excluding the reflected echoes at the detection distance that is less than the threshold distance from identifying the noise echoes and the effective echoes.

[0106] (Technical Idea 8) The control device according to any one of Technical Ideas 1 to 7, wherein monitoring the noise rate includes monitoring the noise rate for each pixel area (46b) defined to include a set number of the detection pixels.

[0107] (Technical Idea 9) The control device according to any one of Technical Ideas 1 to 8, wherein generating the detection data includes generating the detection data so as to report a rainfall amount correlated with the noise rate as the rainfall state.

[0108] (Technical Idea 10) A control device described in any one of Technical Ideas 1 to 9, wherein generating the detection data includes generating the detection data so as to notify the rainfall state in response to the noise rate increasing to a warning range that warns the mobile body (1) on which the optical sensor is mounted.

[0109] (Technical Idea 11) The control device according to Technical Idea 10, wherein monitoring the noise rate includes monitoring the noise rate correlated with the number of effective pixels when the noise rate falls within a monitoring range.

[0110] (Technical Idea 12) An optical sensor that receives a reflected echo (Er) from a target (Ot) in response to a projected beam (Bp) projected into the outside world for each detection cycle (Cd) and outputs detection data (Dd), the optical sensor including the control device described in any one of Technical Ideas 1 to 11, and comprising: a control unit (51) that generates the detection data; a light projecting unit (21) that projects the projected beam in accordance with control by the control unit; and a light receiving unit (41) that receives the reflected echo in accordance with control by the control unit.

[0111] The above-mentioned technical concepts 1 to 11 may be understood as the technical concepts of the method and the program.

Claims

1. A control device having a processor (51b) for controlling an optical sensor (10) that receives a reflected echo (Er) from a target (Ot) in response to a projected beam (Bp) projected to the outside world in each detection cycle (Cd) and outputs detection data (Dd), wherein the processor: acquires, for each detection cycle, an intensity (I) of the reflected echo received by the optical sensor for each detection pixel (46a) of the detection data, in association with a detection distance (L) to the target according to the timing of receiving the reflected echo by the optical sensor; and monitors, for each detection cycle, a noise ratio (R) of the noise pixel number (Nn), which is the number of detection pixels that detected a noise echo (Ern), which is the number of detection pixels that detected a reflected echo identified from raindrops that fell into the outside world, to a corrected pixel number obtained by subtracting the effective pixel number (Nv), which is the number of detection pixels that detected a valid echo (Erv), which is identified as the reflected echo from the target, from the total number of detection pixels (ΣN). generating the detection data indicative of the external rainfall state in accordance with the noise rate.

2. A control device having a processor (51b) for controlling an optical sensor (10) that receives a reflected echo (Er) from a target (Ot) in response to a projected beam (Bp) projected to the outside world in each detection cycle (Cd) and outputs detection data (Dd), wherein the processor: acquires, for each detection cycle, an intensity (I) of the reflected echo received by the optical sensor for each detection pixel (46a) of the detection data in association with a detection distance (L) to the target according to the timing of receiving the reflected echo by the optical sensor; and monitors, for each detection cycle, a noise rate (R) as a ratio of the number of noise echoes (Ern) identified as the reflected echo from raindrops that have fallen into the outside world to a corrected pixel number obtained by subtracting a valid pixel number (Nv), which is the number of detection pixels that detected a valid echo (Erv) identified as the reflected echo from the target, from the total number of detection pixels (ΣN). generating the detection data indicative of the external rainfall state in accordance with the noise rate.

3. The control device according to claim 1 or 2, wherein monitoring the noise rate includes: identifying the reflected echo associated with the detection distance and the received light intensity for each detection pixel as the noise echo within a noise range (LIn) having an upper boundary defined by a threshold intensity (It) for the received light intensity, which decreases as the detection distance increases; and identifying the reflected echo associated with the detection distance and the received light intensity for each detection pixel as the effective echo within an effective range (LIv) having a lower boundary defined by the threshold intensity for the received light intensity.

4. The control device described in claim 3, wherein monitoring the noise rate includes: identifying, as noise echoes, the reflected echoes whose detection distance and received light intensity are within the noise range among the reflected echoes whose light reception timing is the earliest in each detection cycle for each detection pixel; and identifying, as effective echoes, the reflected echoes whose detection distance and received light intensity are within the effective range among the reflected echoes whose light reception timing is the earliest in each detection cycle for each detection pixel.

5. The control device described in claim 4, wherein monitoring the noise rate includes identifying the noise echo by limiting it to the reflected echo that has the earliest light reception timing in each detection cycle for each detection pixel, among the reflected echoes whose detection distance and received light intensity are within the noise range.

6. The control device described in claim 4, wherein monitoring the noise rate includes identifying all reflected echoes detected in the same detection cycle for each detection pixel as noise echoes, among the reflected echoes whose detection distance and received light intensity are within the noise range.

7. The control device described in claim 3, wherein monitoring the noise rate includes identifying the noise echoes and the effective echoes from the reflected echoes at the detection distance that is equal to or greater than a threshold distance (Lt1) corresponding to the position of the detection surface (12a) exposed to the outside world in the optical sensor, and excluding the reflected echoes at the detection distance that is less than the threshold distance from identifying the noise echoes and the effective echoes.

8. The control device according to claim 1 or 2, wherein monitoring the noise rate includes monitoring the noise rate for each pixel area (46b) defined to include a set number of the detection pixels.

9. The control device according to claim 1 or 2, wherein generating the detection data includes generating the detection data so as to report a rainfall amount correlated with the noise rate as the rainfall state.

10. A control device as described in claim 1 or 2, wherein generating the detection data includes generating the detection data so as to notify the rainfall condition in response to the noise rate increasing to a warning range that warns the mobile body (1) on which the optical sensor is mounted.

11. The control device according to claim 10, wherein monitoring the noise rate includes monitoring the noise rate correlated with the number of effective pixels when the noise rate falls within a monitoring range.

12. An optical sensor that receives a reflected echo (Er) from a target (Ot) in response to a projected beam (Bp) projected into the outside world for each detection cycle (Cd) and outputs detection data (Dd), the optical sensor being configured to include the control device described in claim 1 or 2 and comprising: a control unit (51) that generates the detection data; a light projecting unit (21) that projects the projected beam in accordance with the control of the control unit; and a light receiving unit (41) that receives the reflected echo in accordance with the control of the control unit.

13. A control method executed by a processor (51b) for controlling an optical sensor (10) that receives a reflected echo (Er) from a target (Ot) in response to a projected beam (Bp) projected into the outside world in each detection cycle (Cd) and outputs detection data (Dd), comprising: acquiring, for each detection cycle (Cd), an intensity (I) of the reflected echo received by the optical sensor for each detection pixel (46a) of the detection data in association with a detection distance (L) to the target corresponding to the timing of receiving the reflected echo by the optical sensor; and monitoring, for each detection cycle, a noise ratio (R) of the number of noise pixels (Nn), which is the number of detection pixels that detected a noise echo (Ern), which is the number of detection pixels that detected a reflected echo identified from raindrops that fell into the outside world, to a corrected pixel number obtained by subtracting the number of valid pixels (Nv), which is the number of detection pixels that detected a valid echo (Erv), which is identified as the reflected echo from the target, from the total number of detection pixels (ΣN). generating the detection data to notify the external rainfall state in accordance with the noise rate.

14. A control method executed by a processor (51b) for controlling an optical sensor (10) that receives a reflected echo (Er) from a target (Ot) in response to a projected beam (Bp) projected into the outside world in each detection cycle (Cd) and outputs detection data (Dd), comprising: acquiring, for each detection cycle (Cd), an intensity (I) of the reflected echo received by the optical sensor for each detection pixel (46a) of the detection data in association with a detection distance (L) to the target corresponding to the timing of receiving the reflected echo by the optical sensor; and monitoring, for each detection cycle, a noise rate (R) representing the ratio of the number of noise echoes (Ern) identified as the reflected echo from raindrops that have fallen into the outside world to a corrected pixel number obtained by subtracting a number of valid pixels (Nv), which is the number of detection pixels that have detected a valid echo (Erv) identified as the reflected echo from the target, from a total number of detection pixels (ΣN). generating the detection data to notify the external rainfall state in accordance with the noise rate.

15. A control program stored in a storage medium (51a) for controlling an optical sensor (10) that receives a reflected echo (Er) from a target (Ot) in response to a projected beam (Bp) projected to the outside world for each detection cycle (Cd) and outputs detection data (Dd), the control program including instructions for causing a processor (51b) to execute the program, the control program comprising: acquiring, for each detection cycle (Cd), the intensity (I) of the reflected echo received by the optical sensor in association with the detection distance (L) to the target according to the timing of receiving the reflected echo by the optical sensor for each detection pixel (46a) of the detection data; The number of valid pixels (Nv), which is the number of detection pixels that detected the valid echo (Erv) identified as the reflected echo from the target, is subtracted from the total number of detection pixels (ΣN) to correct the corrected number of pixels. The number of noise pixels (Nn), which is the number of detection pixels that detected the noise echo (Ern) identified as the reflected echo from the raindrops that fell in the outside world, accounts for a noise rate (R) in each detection cycle. And the detection data that notifies the rainfall condition in the outside world according to the noise rate.

16. A control program stored in a storage medium (51a) for controlling an optical sensor (10) that receives a reflected echo (Er) from a target (Ot) in response to a projected beam (Bp) projected into the outside world in each detection cycle (Cd) and outputs detection data (Dd), the control program including instructions for causing a processor (51b) to execute the program, the control program comprising: acquiring, for each detection cycle (Cd), the intensity (I) of the reflected echo received by the optical sensor in association with each detection pixel (46a) of the detection data, for a detection distance (L) to the target corresponding to the timing of receiving the reflected echo by the optical sensor; and monitoring, for each detection cycle, the ratio of the number of noise echoes (Ern) identified as the reflected echo from raindrops that have fallen into the outside world to a corrected pixel number obtained by subtracting the number of valid pixels (Nv), which is the number of detection pixels that detected a valid echo (Erv) identified as the reflected echo from the target, from the total number of detection pixels (ΣN), as a noise rate (R). generating the detection data that notifies the rainfall state in the outside world in accordance with the noise rate.

Images