Light detecting device, light detecting method, and light detecting program

Abstract

In relation to the start point timing and the end point timing of a forward period, in an oscillation period of an oscillating mirror, in which an illuminating beam is scanned, a control unit of this light detecting device is configured to acquire the respective actual angles of the oscillating mirror in the previous forward period. The control unit is configured to correct each of a start point command angle and an end point command angle of the present forward period in accordance with an angle deviation between a control command angle and the actual angle at the previous start point timing and end point timing, respectively. The control unit is configured to control the angular velocity of the oscillation by variably setting the control command angle between the start point command angle and the end point command angle for each control timing. The control unit is configured to set the light emission timing of the light source for each set change amount of the actual angle in the present forward period.

Description

Light detection device, light detection method, and light detection program CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2024-5514 filed in Japan on January 17, 2024, and the contents of the original application are incorporated by reference in their entirety.

[0002] The present disclosure relates to optical detection techniques for detecting a reflected beam that is reflected relative to an illumination beam.

[0003] Patent Document 1 discloses an oscillator device that deflects a light beam. The oscillator device executes a control loop that controls an amplitude control value based on the difference between a target oscillation amplitude and a detected oscillation amplitude. The oscillator device sets the gain of the control loop based on the amplitude control value when the oscillation amplitude of the oscillator is the target oscillation amplitude.

[0004] JP 2010-48928 A

[0005] In the technology of Patent Document 1, if one of the maximum and minimum amplitude values ​​meets the target oscillation amplitude while the other does not, it may be difficult to correct only the amplitude value of the other side to the target oscillation amplitude. In other words, since the oscillator device of Patent Document 1 sets the oscillation amplitude by changing the gain of the control loop, changing the gain to correct the amplitude value of the other side to the target oscillation amplitude may also change the amplitude value of one side, potentially causing it to deviate from the target oscillation amplitude. In this case, the deviation in the scanning orientation may increase, potentially reducing scanning accuracy.

[0006] An object of the present disclosure is to provide a photodetection device capable of improving scanning accuracy. Another object of the present disclosure is to provide a photodetection method capable of improving scanning accuracy. Yet another object of the present disclosure is to provide a photodetection program capable of improving scanning accuracy.

[0007] The technical means of the present disclosure for solving the problems will be described below. Note that the reference numerals in parentheses in the claims indicate the correspondence with the specific means described in the embodiments described later in detail, and do not limit the technical scope of the present disclosure.

[0008] a control unit that outputs control commands for the timing of light emission from the light source in the irradiation unit and the angle of the oscillating mirror in the scanning unit, wherein the control unit: acquires the actual angles of the oscillating mirror in the previous forward cycle with respect to the start and end timings of the forward cycle in which the irradiation beam is scanned, of the oscillation cycle of the oscillating mirror; and corrects the start and end command angles, which are the control command angles of the oscillating mirror at the start and end timings of the current forward cycle, according to the angle deviation between the control command angle and the actual angle at the start and end timings of the previous forward cycle; The angular velocity of the oscillation is controlled by variably setting the control command angle between the start point command angle and the end point command angle for each control timing obtained by dividing the start point timing and the end point timing in the current forward cycle, and the light emission timing of the light source is set for each set change amount of the actual angle in the current forward cycle.

[0009] A second aspect of the present disclosure is an optical detection method executed by a processor to control an optical detection device that detects a reflected beam reflected from an illumination beam scanned by an oscillating mirror, the method comprising: acquiring the actual angle of the oscillating mirror in the previous outward cycle for the start point timing and end point timing of the outward cycle in which scanning of the illumination beam is performed, among the oscillation cycles of the oscillating mirror; correcting the start point command angle and end point command angle, which are the control command angles of the oscillating mirror at the start point timing and end point timing of the current outward cycle, according to the angle deviation between the control command angle and the actual angle at the start point timing and end point timing of the previous outward cycle; controlling the angular velocity of the oscillation by variably setting the control command angle between the start point command angle and the end point command angle for each control timing obtained by dividing the start point timing and the end point timing in the current outward cycle; and setting the light emission timing of a light source that generates the illumination beam for each set change amount of the actual angle in the current outward cycle.

[0010] A third aspect of the present disclosure is a light detection program stored in a storage medium and executed by a processor to control a light detection device that detects a reflected beam reflected by an irradiation beam scanned by an oscillating mirror, the program including instructions to be executed by a processor, the instructions including: acquiring the actual angle of the oscillating mirror in the previous outward cycle with respect to the start point timing and end point timing of the outward cycle in which scanning of the irradiation beam is performed, among the oscillation cycles of the oscillating mirror; correcting the start point command angle and end point command angle, which are the control command angles of the oscillating mirror at the start point timing and end point timing of the current outward cycle, according to the angle deviation between the control command angle and the actual angle at the start point timing and end point timing of the previous outward cycle; controlling the angular velocity of the oscillation by variably setting the control command angle between the start point command angle and the end point command angle for each control timing obtained by dividing the period between the start point timing and the end point timing in the current outward cycle; and setting the light emission timing of a light source that generates the irradiation beam for each set change amount of the actual angle in the current outward cycle.

[0011] According to these first to third aspects, the start point command angle and the end point command angle are individually corrected according to the angle deviation, and the angular velocity is controlled between the corrected start point command angle and the end point command angle. Therefore, deviations in the actual angles at the start point timing and the end point timing are suppressed compared to when the control gain is set uniformly according to the angle amplitude. Furthermore, because the light emission timing is set for each set amount of change in the actual angle obtained by controlling the angular velocity between the corrected start point command angle and the end point command angle, deterioration in scanning accuracy due to deviations in the scanning orientation can be suppressed.

[0012] FIG. 1 is a schematic diagram showing the overall configuration of a first embodiment. FIG. 2 is a schematic diagram showing the mechanical configuration of an irradiation unit according to the first embodiment. FIG. 3 is a schematic diagram showing the mechanical configuration of a light-receiving unit according to the first embodiment. FIG. 4 is a block diagram showing the configuration of a control unit according to the first embodiment. FIG. 5 is a block diagram equivalently showing the control content of an amplitude control block. FIG. 6 is a graph showing an example of a control waveform. FIG. 7 is a graph showing the relationship between an oscillation period and a control period. FIG. 8 is a flowchart showing a part of a light detection flow. FIG. 9 is a flowchart showing a part of a light detection flow. FIG. 10 is a flowchart showing a part of a light detection flow. FIG. 11 is a flowchart showing a part of a light detection flow of a second embodiment. FIG. 12 is a graph showing an example of a control waveform of the second embodiment. FIG. 13 is a flowchart showing a part of a light detection flow of a third embodiment. FIG. 14 is a graph showing an example of a control waveform of the third embodiment. FIG. 15 is a flowchart showing a part of a light detection flow of a fourth embodiment. FIG. 16 is a flowchart showing a part of a light detection flow of the fourth embodiment.

[0013] 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.

[0014] 1 detects a reflected beam of an illumination beam. The illumination beam detection device 1 is a so-called LiDAR (Light Detection and Ranging / Laser Imaging Detection and Ranging) device that can detect the distance to a target that has reflected the illumination beam by detecting the reflected beam.

[0015] The light detection device 1 is mounted on a vehicle 5. The vehicle 5 is a mobile body, such as an automobile, capable of traveling on a roadway with an occupant on board. The vehicle 5 is capable of steady or temporary autonomous driving in an autonomous driving control mode. Here, the autonomous driving control mode may be realized by autonomous driving control, such as conditional automated driving, highly automated driving, or fully automated driving, in which a system performs all driving tasks when activated. The autonomous driving control mode may also be realized by advanced driving assistance control, such as driving assistance or partial automated driving, in which an occupant performs some or all driving tasks. The autonomous driving control mode may be realized by either autonomous driving control or advanced driving assistance control, or by a combination of these, or by switching between them. Such a vehicle 5 is also referred to as an autonomous vehicle or an autonomous robot.

[0016] In the following description, unless otherwise specified, the directions of front, rear, up, down, left, and right are defined with respect to the vehicle 5 on a horizontal plane. The horizontal direction refers to a direction parallel to the horizontal plane that serves as the directional reference for the vehicle 5. The vertical direction refers to a vertical direction that is also the up-down direction with respect to the horizontal plane that serves as the directional reference for the vehicle 5.

[0017] The light detection device 1 acquires image data that can be used for driving control of the vehicle 5, including an automatic control driving mode. The light detection device 1 is disposed in at least one location on the vehicle 5, such as the front, left and right side portions, rear portion, or upper roof.

[0018] In the photodetector 1, a three-dimensional orthogonal coordinate system is defined by an X-axis, a Y-axis, and a Z-axis, which are three mutually orthogonal axes. In particular, in this embodiment, the X-axis and the Z-axis are set along different horizontal directions of the vehicle 5, and the Y-axis is set along the vertical direction of the vehicle 5. Note that in Fig. 1, the left side of the dashed dotted line along the Y-axis (the side of a translucent panel 12, which will be described later) actually illustrates a cross section perpendicular to the right side of the dashed dotted line (the side of modules 21 and 41, which will be described later) where the three-dimensional orthogonal coordinate system is given.

[0019] The photodetector 1 emits light toward a sensing area As corresponding to the installation location and viewing angle in the external space of the vehicle 5. The photodetector 1 receives reflected light that is incident when the emitted light is reflected from the sensing area As. In response to receiving the reflected light from the emitted beam, the photodetector 1 senses a target that reflects light within the sensing area As. Here, sensing means measuring at least the reflection point distance from the photodetector 1 to the target and the reflection intensity from the target.

[0020] A typical sensing target in the optical detection device 1 applied to the vehicle 5 may be at least one of moving objects such as a pedestrian, a cyclist, a non-human animal, and another vehicle. A typical sensing target in the optical detection device 1 applied to the vehicle 5 may be at least one of stationary objects such as a guardrail, a road sign, a roadside structure, and an object fallen on the road.

[0021] The light detection device 1 includes a casing module 10, a light-projecting module 21, a scanning unit 31, a light-receiving module 41, and a control unit 100. The casing module 10 includes a housing 11 and a light-transmitting panel 12. The housing 11 is formed in a hollow box shape and is mainly made of a light-blocking material such as metal or synthetic resin. The housing 11 houses the light-projecting module 21, the scanning unit 31, and the light-receiving module 41 inside. The housing 11 holds the light-transmitting panel 12, which is formed in a plate shape from a light-transmitting material such as glass or synthetic resin.

[0022] The light-projecting module 21 includes an irradiation unit 22 and a light-projecting lens system 26. As shown in Fig. 2, the irradiation unit 22 is constructed by mounting a plurality of light-emitting diodes 24 as light sources in an array on a substrate 23. Each light-emitting diode 24 generates pulsed infrared laser light that serves as an irradiation beam for the sensing area As under the control of the control unit 100. Each of these light-emitting diodes 24 is provided as a laser diode, such as an edge-emitter laser or a vertical cavity surface-emitting laser (VCSEL).

[0023] As shown in FIG. 1 , the projection lens system 26 projects an irradiation beam generated by light emitted from the irradiation unit 22 toward the oscillating mirror 32 of the scanning unit 31. The projection lens system 26 performs at least one optical function, such as focusing, collimating, and shaping. The projection lens system 26 forms a projection optical axis along the Z axis. The projection lens system 26 has at least one projection lens on the projection optical axis, the lens shape of which corresponds to the optical function to be performed. The irradiation unit 22 is positioned on the projection optical axis of the projection lens system 26. The irradiation beam generated by light emitted by each light-emitting diode 24 in the irradiation unit 22 is guided along the projection optical axis of the projection lens system 26.

[0024] The scanning unit 31 includes an oscillating mirror 32, a biasing member 34, and a scanning motor 35. The oscillating mirror 32 is formed into a plate shape by depositing a reflective film on a reflective surface 33, which is one side of a base material. The oscillating mirror 32 is supported by the housing 11 so as to be rotatable about a rotation center line along the Y axis. The oscillating mirror 32 oscillates back and forth within a drive range that is limited by the function of a mechanical or electrical stopper.

[0025] The oscillating mirror 32 is provided in common to the light-projecting module 21 and the light-receiving module 41. The oscillating mirror 32 irradiates the sensing area As with an illumination beam incident from the projection lens system 26 of the light-projecting module 21 by reflection from a reflecting surface 33 whose orientation corresponds to the rotation angle, through the light-transmitting panel 12, thereby scanning the area As both temporally and spatially. In particular, in the photodetector 1, mechanical scanning of the sensing area As with the illumination beam is substantially limited to scanning in the horizontal direction.

[0026] Simultaneously with this scanning, the oscillating mirror 32 further reflects the reflected light incident from the sensing area As through the light-transmitting panel 12 toward the light-receiving module 41 by the reflecting surface 33 oriented according to the rotation angle. Here, the speeds of the illumination beam and the reflected light are sufficiently high compared to the rotational speed of the oscillating mirror 32. As a result, the reflected light of the illumination beam is guided toward the light-receiving module 41 so as to travel in the opposite direction to the illumination beam by the oscillating mirror 32, which has approximately the same rotation angle as the illumination beam.

[0027] The biasing member 34 is made of an elastic body such as a spring. One end of the biasing member 34 is fixed to the oscillating mirror 32, and the other end is fixed directly or indirectly to the housing 11. The biasing member 34 is provided so as to bias the oscillating mirror 32 in a specific rotational direction. For example, if the rotational direction in which the irradiation beam is irradiated is defined as the forward direction and the direction opposite to the forward direction is defined as the backward direction, the oscillating mirror 32 is biased in the backward direction.

[0028] The scanning motor 35 is, for example, a voice coil motor, a brushed DC motor, or a stepping motor. The scanning motor 35 drives (i.e., drives) the oscillating mirror 32 to rotate within the finite driving range described above under the control of the control unit 100. The scanning motor 35 drives and rotates the oscillating mirror 32 in the forward direction against the biasing force of the biasing member 34. At this time, the rotation angle of the oscillating mirror 32 is sequentially changed in synchronization with the light emission cycle of the irradiation unit 22 of the light projecting module 21. Meanwhile, in the backward direction, the scanning motor 35 drives and rotates the oscillating mirror 32 in response to the biasing force of the biasing member 34. In this way, the scanning motor 35 causes the oscillating mirror 32 to swing back and forth.

[0029] The light-receiving module 41 is disposed offset in the Y-axis direction relative to the light-projecting module 21. The light-receiving module 41 includes a light-receiving lens system 42 and a light-receiving unit 45. The light-receiving lens system 42 exerts an optical function to image the light reflected from the sensing area As onto the light-receiving unit 45. The light-receiving lens system 42 forms a light-receiving optical axis along the Z-axis. The light-receiving lens system 42 has at least one light-receiving lens on the light-receiving optical axis, the lens shape of which corresponds to the optical function to be exerted. The reflected light incident from the reflecting surface 33 of the oscillating mirror 32 is guided along the light-receiving optical axis of the light-receiving lens system 42, regardless of the rotation angle of the oscillating mirror 32 within the driving section.

[0030] The light receiving unit 45 is positioned on the light receiving optical axis of the light receiving lens system 42. As shown in FIG. 3 , the light receiving unit 45 is constructed by arranging a plurality of light receiving pixels 46 in an array on a substrate. Each light receiving pixel 46 is further constructed from a plurality of light receiving elements 460. The light receiving elements 460 of each light receiving pixel 46 are mainly composed of photodiodes such as single photon avalanche diodes (SPADs). With this configuration, each light receiving pixel 46 receives reflected light incident from the light receiving lens system 42 with each light receiving element 460.

[0031] 1, the light receiving unit 45 is integrally provided with an output circuit 48. The output circuit 48 performs sampling processing under control of the control unit 100 for each scanning line associated with the rotation angle of the oscillating mirror 32 according to the light emission cycle. Thus, through the sampling processing, the output circuit 48 generates light reception data for each scanning line based on the output signal from each light receiving pixel 46 of the light receiving unit 45. The light reception data generated in this manner is output from the output circuit 48 to the control unit 100.

[0032] The control unit 100 is connected to the light-emitting diode 24, the scanning motor 35, and the light-receiving unit 45 via at least one of, for example, a local area network (LAN) line, a wire harness, an internal bus, etc. For example, the control unit 100 is housed inside a housing 11 as shown in Fig. 1. The control unit 100 is configured to include at least one dedicated computer.

[0033] The dedicated computer constituting the control unit 100 may be a light detection control ECU (Electronic Control Unit) specialized for controlling the light detection device 1. The dedicated computer constituting the control unit 100 may be a sensor ECU that comprehensively controls multiple types of in-vehicle sensors including the light detection device 1.

[0034] The dedicated computer constituting the control unit 100 has at least one memory 101 and one processor 102. The memory 101 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. Here, "storage" may refer to accumulation in which data is retained even when the vehicle 5 is turned off, or temporary storage in which data is erased when the vehicle 5 is turned off. The processor 102 includes at least one type of core selected from a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a RISC (Reduced Instruction Set Computer)-CPU, a CISC (Complex Instruction Set Computer)-CPU, a DFP (Data Flow Processor), and a GSP (Graph Streaming Processor).

[0035] In the control unit 100, the processor 102 executes a plurality of instructions contained in a light detection program stored in a memory 101 serving as a storage medium in order to control the irradiation unit and the scanning unit. As a result, the control unit 100 constructs a plurality of functional blocks for controlling the irradiation unit and the scanning unit. The functional blocks constructed in the control unit 100 include an angle command block 110, a drive control block 170, a light emission control block 180, and a distance measurement block 190, as shown in FIG. 4 .

[0036] The angle command block 110 generates a control command angle as an angle command value for controlling the swing angle of the swing mirror 32. The angle command block 110 includes a counter block 120, an angle acquisition block 130, an amplitude control block 140, and an angle setting block 150 as sub-function blocks.

[0037] The counter block 120 functions as a counter that counts at the period of the oscillation waveform (oscillation period), and is reset at each oscillation period. The counter block 120 outputs a count value and a reset timing at each oscillation period.

[0038] The angle acquisition block 130 sequentially acquires the angle detection value of the oscillating mirror 32 output from the angle sensor 50 that detects the angle of the oscillating mirror 32 as the actual angle of the oscillating mirror 32. In particular, the angle acquisition block 130 acquires the actual angle at the start timing t0 and the end timing t1 of the forward cycle of the oscillating period of the oscillating mirror 32, during which the irradiation beam scans. For example, of the angle detection values ​​sequentially output from the angle sensor 50, the angle acquisition block 130 holds the minimum angle value as the actual angle at the start timing t0 and the maximum angle value as the actual angle at the end timing t1. When the angle acquisition block 130 receives a reset timing from the counter block 120, it initializes the held maximum angle value and minimum angle value. Note that, hereinafter, the actual angle of the oscillating mirror 32 at the start timing t0 may be referred to as the actual start angle, and the actual angle of the oscillating mirror 32 at the end timing t1 may be referred to as the actual end angle.

[0039] The amplitude control block 140 controls the values ​​of the start point command angle and the end point command angle in the forward cycle following the forward cycle in which the actual start point angle and the actual end point angle were acquired. Here, from a perspective centered on the "next forward cycle," the "next forward cycle" can also be referred to as the "current forward cycle." In this case, the forward cycle in which the actual start point angle and the actual end point angle were acquired can also be referred to as the "previous forward cycle." The amplitude control block 140 acquires the start point command angle for the current forward cycle by correcting the start point command angle for the previous forward cycle according to the angle deviation from the actual start point angle for the previous forward cycle. Similarly, the amplitude control block 140 acquires the end point command angle for the current forward cycle by correcting the end point command angle for the previous forward cycle according to the angle deviation from the actual end point angle for the previous forward cycle. Hereinafter, the "previous forward cycle" may be simply referred to as the "previous," and the "current forward cycle" may be simply referred to as the "current."

[0040] For example, the amplitude control block 140 provides feedback control that outputs a current control command angle according to feedback of the previous angle deviation, as shown in Fig. 5. As shown in Fig. 5, the control performed by the amplitude control block 140 is equivalent to PI control using a subtractor 141, multipliers 142 and 144, an integrator 143, and adders 145 and 146.

[0041] When acquiring the start point command angle, a subtractor 141 calculates the difference between the previous start point command angle a0 + AL_1 and the previous minimum angle value, and acquires the difference as an angle deviation (start point angle deviation). A multiplier 142 multiplies the angle deviation by a P control gain to acquire a proportional term for PI control. An integrator 143 integrates the angle deviation and outputs the result to a multiplier 144. The multiplier 144 then multiplies the integrated angle deviation by an I control gain to acquire an integral term for PI control. The integrator 143 uses a value stored in advance in the memory 101 or the like at the time of shipment from the factory as the initial value of the I control gain. An adder 145 adds the proportional term and the integral term to acquire a correction amount according to the angle deviation. The adder 146 adds the correction amount AL_2 to the start point target angle a0, which is preset as the target angle to which the actual angle at the start point timing t0 converges, to obtain the corrected current start point command angle a0+AL_2.

[0042] The amplitude control block 140 described above functions similarly when acquiring an end point command angle. When acquiring an end point command angle, the amplitude control block 140 functions by replacing "start point" with "end point" in the above description. That is, the amplitude control block 140 acquires a correction amount AH_2 corresponding to the end point angle deviation between the previous end point command angle a1+AH_1 and the previous maximum angle value, and adds the correction amount AH_2 to the end point target angle a1 to acquire the current end point command angle a1+AH_2. The amplitude control block 140 acquires the above start point command angle and end point command angle for each swing cycle. For example, as shown in FIG. 6 , at the amplitude update timing tu set during a return cycle, the amplitude control block 140 acquires the start point command angle and end point command angle for the immediately following forward cycle. Note that in the graphs of FIG. 6 and the like, the solid line indicates the control command angle, and the dashed line indicates the angle detection value.

[0043] The angle setting block 150 variably sets a control command angle for each control timing obtained by dividing the period between the start point timing t0 and the end point timing t1 in the forward cycle. The control timing is specified by a control period that is shorter than the swing period and corresponds to a counter value (see FIG. 7 ). The angle setting block 150 sets a control command angle for each control timing according to the angle command table 160, the counter value, the start point command angle, and the end point command angle. Here, the angle command table 160 is data indicating the initial value of each control command angle for each control timing from the start point timing t0 to the end point timing t1. For example, the initial value of the control command angle is set as a value that increases linearly from the start point target angle to the end point target angle.

[0044] The angle setting block 150 sets an actual control command angle by correcting the initial value of the control command angle in the angle command table 160 corresponding to the counter value for each control timing. Specifically, the angle setting block 150 sets the actual control command angle for each control timing by linear interpolation between the current start point command angle and end point command angle. By variably setting the control command angle for each control timing, the angular velocity of the oscillation of the oscillating mirror 32 is successively controlled.

[0045] The drive control block 170 outputs a voltage command value for driving the oscillating mirror 32. For example, the drive control block 170 compares the control command angle with the angle detection value and outputs a voltage command value according to feedback control that multiplies the difference by a gain. In the case of feedback control, the drive control block 170 may perform angular velocity control or current control at different cycles as an inner loop inside the angle control. Note that the drive control block 170 may output a voltage command value according to open-loop control that uses the control command angle without using the angle detection value.

[0046] The drive control block 170 generates a voltage signal corresponding to the voltage command value as a drive signal for driving the scanning motor 35. The drive control block 170 outputs the generated drive signal to the scanning motor 35 as a control command, thereby driving the scanning motor 35 to rotate.

[0047] The light emission control block 180 controls the light emission timing of the irradiation unit 22. The light emission control block 180 acquires an angle detection value and outputs a drive signal to the irradiation unit 22 for each set change in the angle detection value in the forward cycle. The set change is set in advance as an angle change amount based on, for example, the upper limit number of times light is emitted per pixel according to the angular velocity.

[0048] The ranging block 190 acquires light reception data for each scanning line output from the output circuit 48 of the light receiving unit 45. The ranging block 190 generates ranging information based on the light reception data by sensing at least the reflection point distance from the light detection device 1 to the target. The ranging block 190 outputs the generated ranging information to the outside of the light detection device 1. The ranging information may be output to, for example, an integrated ECU that integrates the driving control of the vehicle 5. The ranging information may be output to a recognition ECU that recognizes the external environment in the driving control of the vehicle 5. The ranging information may be output to a sensing ECU that processes sensing information from on-board sensors including the light detection device 1.

[0049] The photodetection method in which the control unit 100 controls the scanning unit and the irradiation unit 22 through the cooperation of the blocks 110, 170, 180, and 190 described above is executed according to the photodetection flows shown in Figures 8 to 10. The photodetection flow includes the amplitude correction flow of Figure 8, which is executed for each oscillation period, the angular velocity control flow of Figure 9, which is executed for each control period, and the distance measurement flow of Figure 10, which is executed for each distance measurement period. This photodetection flow is executed repeatedly while the photodetector 1 is running. Note that each "S" in this photodetection flow represents multiple steps executed by multiple commands included in the photodetection program.

[0050] 8 , first, in S10, the counter block 120 resets the counter value up to the immediately preceding oscillation cycle. Next, in S20, the angle acquisition block 130 acquires the maximum and minimum angle values ​​in the forward cycle as the actual angles of the oscillating mirror 32 at the start point timing t0 and the end point timing t1. Then, in S30, the amplitude control block 140 corrects the start point command angle for the next forward cycle in accordance with the previous start point angle deviation, and corrects the end point command angle in accordance with the previous end point angle deviation.

[0051] Next, as shown in the angular velocity control flow of FIG. 9 , in each control cycle, first, in S100, the counter block 120 increments the counter value. Next, in S110, the angle setting block 150 acquires a control command angle corresponding to linear interpolation of the start point command angle and the end point command angle corrected in the previous oscillation cycle. Then, in S120, the drive control block 170 acquires a current angle detection value from the angle sensor 50. Next, in S130, the drive control block 170 acquires a voltage command value corresponding to the acquired angle detection value. Then, in S140, the drive control block 170 outputs a drive voltage corresponding to the voltage command value to the scanning motor 35.

[0052] Next, the distance measurement flow executed for each distance measurement cycle will be described below with reference to Fig. 10. First, in S200, the light emission control block 180 acquires an angle detection value. Next, in S210, the light emission control block 180 determines whether the oscillating mirror 32 has been rotated by the set change amount based on the angle detection value.

[0053] If it is determined that the mirror 32 has not been rotated by the set amount of change, the flow returns to S200. On the other hand, if it is determined that the mirror 32 has been rotated by the set amount of change, the flow proceeds to S220. In S220, the light emission control block 180 outputs a drive signal to the irradiation unit 22 to cause the irradiation unit 22 to emit light. Through the processing of S200, S210, and S220, control of the light emission timing in accordance with the change in angle of the oscillating mirror 32 is executed.

[0054] In S230 following S220, the distance measurement block 190 acquires light reception data from the output circuit 48 of the light receiving unit 45. Then, in S240, the distance measurement block 190 outputs distance measurement information based on the light reception data.

[0055] According to the first embodiment described above, the start point command angle and the end point command angle in the current outward movement cycle are corrected in accordance with the angle deviation in the previous outward movement cycle. Then, the angular velocity of the swing is controlled by variably setting the control command angle between the start point command angle and the end point command angle for each control timing. Furthermore, the light-emitting timing of the light-emitting diode 24 is set for each set change amount of the actual angle. Therefore, the start point command angle and the end point command angle are individually corrected in accordance with the angle deviation, and the angular velocity is controlled between the corrected start point command angle and the end point command angle. Therefore, deviations in the actual angles at the start point timing t0 and the end point timing t1 are suppressed compared to when the control gain is uniformly set in accordance with the angle amplitude. Then, because the light-emitting timing is set for each set change amount of the actual angle whose angular velocity is controlled between the corrected start point command angle and the end point command angle, degradation of the scanning accuracy due to deviations in the scanning orientation can be suppressed.

[0056] Furthermore, according to the first embodiment, the angular velocity is linearly controlled, so that fluctuations in the angular velocity due to linear control can be suppressed.

[0057] Furthermore, according to the first embodiment, the oscillating mirror 32 is biased toward the return path, which makes it possible to reduce the scanning accuracy in the photodetector 1 in which the angle control during scanning in the forward path is likely to be affected by an assembly error or the like of the oscillating mirror 32 that is biased in the reverse direction when emitting light in the forward path.

[0058] Second Embodiment As shown in FIGS. 11 and 12, the second embodiment is a modification of the first embodiment.

[0059] In the second embodiment, the amplitude correction flow proceeds to S40 after S30 as shown in FIG. 11 . In S40, the amplitude control block 140 determines whether an angular velocity condition for correcting the end point timing t1 is met. The angular velocity condition is met when the angular velocity in the previous forward cycle needs to be adjusted. For example, the angular velocity condition is met when the angular velocity falls outside the allowable angular velocity range. Here, the allowable angular velocity range is a range in which the angular velocity is less than or equal to an upper threshold and greater than or equal to a lower threshold. The angular velocity condition may be determined based on whether the angular velocity estimated from, for example, a change in the detected angle over time falls within the allowable velocity range. The angular velocity condition may also be determined based on whether the instantaneous current value flowing through the scanning motor 35 during the backward cycle rises outside the allowable current value range. An increase in the instantaneous current value during the backward cycle outside the allowable current value range corresponds to an excessive angular velocity during the backward cycle, i.e., a decrease in the angular velocity during the forward cycle outside the allowable angular velocity range.

[0060] If it is determined that the angular velocity is within the allowable angular velocity range, the amplitude correction flow skips S50. On the other hand, if it is determined that the angular velocity is outside the allowable angular velocity range, the amplitude correction flow proceeds to S50. In S50, the amplitude control block 140 sets a correction value for the end point timing t1 that brings the angular velocity into the allowable angular velocity range.

[0061] For example, if the angular velocity has risen outside the allowable angular velocity range, i.e., if it is equal to or exceeds the upper threshold, the amplitude control block 140 sets a correction value that delays the end point timing t1. On the other hand, if the angular velocity has fallen outside the allowable angular velocity range, i.e., if it is equal to or less than the lower threshold, the amplitude control block 140 sets a correction value that advances the end point timing t1.

[0062] In accordance with the amplitude correction flow described above, a control command angle is set in S110 of the angular velocity control flow. That is, when a correction value for the end point timing t1 is set, in S110, the angle setting block 150 sets a control command angle by linear interpolation for each control period divided between the start point timing t0 and the corrected end point timing t1, as shown in FIG.

[0063] Furthermore, in accordance with the amplitude correction flow described above, in S210 of the distance measurement flow, a determination process is performed using a set change amount that correlates with the upper limit of the number of times light can be emitted per pixel depending on the angular velocity. That is, when a correction value for the end point timing t1 is set, in S210, the light emission control block 180 determines whether the oscillating mirror 32 has been rotated by the set change amount corresponding to the correction value. For example, if a correction value that delays the end point timing t1 is set, the light emission control block 180 performs the determination process using a smaller set change amount because the angular velocity of the outbound movement becomes slower, thereby increasing the upper limit of the number of times light can be emitted per pixel. On the other hand, if a correction value that advances the end point timing t1 is set, the light emission control block 180 performs the determination process using a larger set change amount because the angular velocity of the outbound movement becomes faster, thereby decreasing the upper limit of the number of times light can be emitted per pixel.

[0064] According to the second embodiment described above, when the angular velocity falls outside the allowable angular velocity range, control is executed to bring the angular velocity within the allowable angular velocity range, which can prevent the number of times that light can be emitted per pixel from decreasing due to an excessively large angular velocity, thereby making it possible to avoid a decrease in the S / N ratio.

[0065] Third Embodiment As shown in FIGS. 13 and 14, the third embodiment is a modification of the first embodiment.

[0066] In the third embodiment, the amplitude control block 140 controls an intermediate command angle in addition to a start point command angle and an end point command angle. The intermediate command angle is a control command angle at an intermediate timing between the start point timing t0 and the end point timing t1 in the forward cycle. As with the start point command angle and the end point command angle, a targeted intermediate target angle is set for the intermediate command angle.

[0067] The intermediate target angle is set so as to impart different linearities to the angular velocity before and after the intermediate timing. In the example shown in Fig. 14, the intermediate target angle is set so that the angular velocity is greater in the section from the intermediate timing to the end timing t1 than in the section from the start timing t0 to the intermediate timing.

[0068] In the third embodiment, the amplitude correction flow proceeds to S21 after S10 as shown in FIG. 13 . In S21, the amplitude control block 140 acquires the angle detection value at the intermediate timing as an angle intermediate value, which is the actual angle at the intermediate timing. Next, in S31, the amplitude control block 140 corrects and sets an intermediate command angle in addition to the start point command angle and the end point command angle. For example, the amplitude control block 140 may correct the intermediate command angle by feedback control such as PI control, in the same way as the start point command angle and the end point command angle.

[0069] According to the amplitude correction flow described above, in S110 of the angular velocity control flow, the control command angle is set with different linearity before and after the intermediate timing. That is, angle setting block 150 in S110 sets the control command angle by different linear interpolation for each control timing divided between the start timing t0 and the intermediate timing and for each control timing divided between the intermediate timing and the end timing t1.

[0070] Furthermore, in accordance with the amplitude correction flow described above, in S210 of the distance measurement flow, a determination process is performed using a set change amount that correlates with the upper limit of the number of times light is emitted per pixel according to the angular velocity before and after the intermediate timing. That is, in S210, the light emission control block 180 determines the rotational drive angle of the oscillating mirror 32 using different set change amounts before and after the intermediate timing. In the example shown in Fig. 14, the light emission control block 180 performs the determination process using a set change amount that is smaller in the section before the intermediate timing than in the section after the intermediate timing.

[0071] According to the third embodiment described above, the previous angle deviation is acquired for the intermediate timing between the start point timing t0 and the end point timing t1, and the intermediate command angle at the current intermediate timing is corrected in accordance with the previous angle deviation. Therefore, it is possible to set a different control command angle in advance between the start point timing t0 and the end point timing t1. This improves the degree of freedom in setting the control angle waveform in the oscillation cycle.

[0072] Furthermore, according to the third embodiment, the angular velocity resulting from the variable setting of the control command angle for each control timing in the current forward cycle is given different linearities before and after the intermediate timing. This makes it possible to set different sections of angular velocity before and after the intermediate timing within one forward cycle. This makes it possible to perform more accurate distance measurement for a portion of the scanning area.

[0073] Fourth Embodiment As shown in FIGS. 15 to 17, the fourth embodiment is a modification of the first embodiment.

[0074] In the fourth embodiment, the amplitude correction flow proceeds to S60 after S30, as shown in FIG. 15 . In S60, the angle acquisition block 130 determines whether the maximum angle value and the minimum angle value have converged to their respective target ranges. For example, the angle acquisition block 130 determines that the angle deviation has converged when a predetermined number of consecutive oscillation cycles have occurred in which the minimum angle value falls within the target start angle range and the maximum angle value falls within the target end angle range. Here, the target start angle range is an angle range that includes the start target angle, and the target end angle range is an angle range that includes the end target angle.

[0075] If it is determined that the angles have not converged to the target ranges, the flow proceeds to S70. In S70, the angle acquisition block 130 prohibits the irradiation unit 22 from emitting light. For example, the angle acquisition block 130 sets a light emission prohibition flag in the memory 101 or the like. On the other hand, if it is determined that the maximum angle value and the minimum angle value have converged to their respective target ranges, the flow proceeds to S80. In S80, the angle acquisition block 130 cancels the prohibition on light emission of the irradiation unit 22. For example, the angle acquisition block 130 erases the light emission prohibition flag set in the memory 101 or the like.

[0076] In accordance with the amplitude correction flow described above, in the distance measurement flow shown in FIG. 16, a process for determining whether or not light emission is prohibited is performed before the light emission process. That is, in the distance measurement flow of the fourth embodiment, first, in S200a, the light emission control block 180 determines whether or not light emission is prohibited. For example, the light emission control block 180 determines that light emission is prohibited when the light emission prohibition flag is set to ON by accessing the memory 101 or the like. The process of S200a is repeated until the prohibition of light emission is lifted. If it is determined that light emission is not prohibited, the flow proceeds to S200b. The process of S200b is the same as the process of S200. Through the processes of S60, S70, S80, and S200a, light emission and output of distance measurement information are performed after the maximum angle value and the minimum angle value are within their respective target ranges, as shown in FIG. 17.

[0077] According to the fourth embodiment described above, distance measurement is started when the angle deviation converges within the allowable range after startup, and distance measurement results can be output after the actual angles at the start point timing t0 and the end point timing t1 have stabilized.

[0078] (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.

[0079] In a modified example, the control unit 100 may be provided outside the housing 11 .

[0080] In a variant, the control unit 100 may control the angular velocity non-linearly.

[0081] In a modified example, the control unit 100 may perform so-called PID control by further adding a differential control to the correction of the control command angle.

[0082] In a modified example, the control unit 100 may prohibit light emission until the angular velocity converges to the allowable angular velocity range.

[0083] In a modified example, the dedicated computer constituting the control unit 100 may be an integration ECU that integrates the driving control of the vehicle 5. The dedicated computer constituting the control unit 100 may be a determination ECU that determines a driving task in the driving control of the vehicle 5. The dedicated computer constituting the control unit 100 may be a monitoring ECU that monitors the driving control of the vehicle 5. The dedicated computer constituting the control unit 100 may be an evaluation ECU that evaluates the driving control of the vehicle 5.

[0084] The dedicated computer constituting the control unit 100 may be a navigation ECU that navigates the driving route of the vehicle 5. The dedicated computer constituting the control unit 100 may be a locator ECU that estimates the self-state quantity of the vehicle 5. The dedicated computer constituting the control unit 100 may be an actuator ECU that controls the driving actuators of the vehicle 5. The dedicated computer constituting the control unit 100 may be an HCU (Human Machine Interface (HMI) Control Unit) that controls the presentation of information in the vehicle 5.

[0085] In a modified example, the dedicated computer constituting the control unit 100 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 the following: 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.

[0086] In a modified example, the mobile body to which the control unit 100 is applied may be, for example, an autonomous robot capable of transporting luggage or collecting information by autonomous or remote driving. In addition to the forms described so far, the above-described embodiments and modified examples may be implemented as a control device that is configured to be mountable on a mobile body and has at least one processor 102 and one memory 101. Specifically, the above-described embodiments and modified examples may be implemented in the form of a processing circuit (e.g., a processing ECU, etc.) or a semiconductor device (e.g., a semiconductor chip, etc.).

[0087] (Disclosure of Technical Ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be described in a multiple dependent form, with the subsequent clause alternatively referring to the preceding clause. Furthermore, some clauses may be described in a multiple dependent form, with the subsequent clause referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0088] (Technical Idea 1) A light detection device for detecting a reflected beam reflected from an illumination beam, comprising: an illumination unit (22) for generating and irradiating the illumination beam by light emission from a light source (24); a scanning unit (31) including an oscillating mirror (32) that oscillates back and forth to scan the illumination beam; a light receiving unit (45) for receiving the reflected beam; and a control unit (100) for outputting control commands regarding the light emission timing of the light source in the illumination unit and the angle of the oscillating mirror in the scanning unit, wherein the control unit: acquires the actual angle of the oscillating mirror in the previous outward cycle with respect to the start timing (t0) and end timing (t1) of the outward cycle in which scanning of the illumination beam is performed within the oscillation cycle of the oscillating mirror; correcting a start point command angle and an end point command angle, which are control command angles of the oscillating mirror at the start point timing and the end point timing in the current outward cycle, respectively, in accordance with an angle deviation between the control command angle and the actual angle at the start point timing and the end point timing in the previous outward cycle; controlling an angular velocity of oscillation by variably setting the control command angle between the start point command angle and the end point command angle for each control timing obtained by dividing the start point timing and the end point timing in the current outward cycle; and setting a light emission timing of the light source for each set change amount of the actual angle in the current outward cycle.

[0089] (Technical Concept 2) The photodetector according to Technical Concept 1, wherein controlling the angular velocity includes linearly controlling the angular velocity.

[0090] (Technical Concept 3) The photodetector according to Technical Concept 1 or 2, wherein the oscillating mirror is biased toward the return path.

[0091] (Technical Idea 4) The control unit is configured to perform ranging, and performing ranging includes starting ranging when the actual angle at the start point timing and the end point timing converges within an allowable range after startup, in an optical detection device described in any one of Technical Ideas 1 to 3.

[0092] (Technical Idea 5) An optical detection device described in any one of Technical Ideas 1 to 4, wherein controlling the angular velocity includes, when the angular velocity falls outside an allowable angular velocity range, performing control to bring the angular velocity within an allowable angular velocity range.

[0093] (Technical Idea 6) An optical detection device described in any one of Technical Ideas 1 to 5, wherein acquiring the angle deviation includes acquiring the angle deviation in the previous outward cycle with respect to an intermediate timing between the start point timing and the end point timing, and correcting the start point command angle and the end point command angle includes correcting an intermediate command angle, which is the control command angle at the intermediate timing in the current outward cycle, according to the angle deviation in the previous outward cycle.

[0094] (Technical Idea 7) The optical detection device according to Technical Idea 6, wherein controlling the angular velocity includes linearly controlling the angular velocity and imparting different linearities before and after the intermediate timing to the angular velocity by variably setting the control command angle for each control timing in the current forward cycle.

[0095] The above technical ideas 1 to 7 may be implemented in the form of a light detection method and a light detection program.

Claims

1. A light detection device that detects a reflected beam reflected with respect to an irradiation beam, comprising: an irradiation unit (22) that generates and irradiates the irradiation beam by light emission of a light source (24); a scanning unit (31) including a swing mirror (32) that swings back and forth to scan the irradiation beam; a light receiving unit (45) that receives the reflected beam; and a control unit (100) that outputs control commands regarding the light emission timing of the light source in the irradiation unit and the angle of the swing mirror in the scanning unit, wherein the control unit, regarding the start point timing (t0) and the end point timing (t1) of the forward path period for executing the scanning of the irradiation beam among the swing periods of the swing mirror, respectively obtains the actual angles of the swing mirror in the previous forward path period; corrects the start point command angle and the end point command angle, which are the respective control command angles of the swing mirror at the start point timing and the end point timing in the current forward path period, according to the angle deviations between the control command angles and the actual angles at the start point timing and the end point timing in the previous forward path period; controls the angular velocity of the swing by variably setting the control command angle between the start point command angle and the end point command angle for each control timing obtained by dividing the period between the start point timing and the end point timing in the current forward path period; and sets the light emission timing of the light source according to each set change amount of the actual angle in the current forward path period. A light detection device configured to perform the above operations.

2. The light detection device according to claim 1, wherein controlling the angular velocity includes linearly controlling the angular velocity.

3. The light detection device according to claim 1, wherein the swing mirror is provided biased toward the return path side.

4. The control unit is configured to perform distance measurement, and performing distance measurement includes starting distance measurement when the actual angles at the start point timing and the end point timing converge within an allowable range after startup. The light detection device according to claim 1.

5. The light detection device according to claim 1, wherein controlling the angular velocity includes performing control to bring the angular velocity within an allowable angular velocity range when the angular velocity is outside the allowable angular velocity range.

6. Obtaining the angle deviation includes obtaining the angle deviation in the previous forward path cycle with respect to an intermediate timing between the start timing and the end timing, and correcting the start command angle and the end command angle includes correcting an intermediate command angle, which is the control command angle at the intermediate timing in the current forward path cycle, according to the angle deviation in the previous forward path cycle. The optical detection device according to claim 1.

7. Controlling the angular velocity includes linearly controlling the angular velocity and imparting different linearities to the angular velocity due to variable setting of the control command angle for each control timing in the current forward path cycle before and after the intermediate timing. The optical detection device according to claim 6.

8. An optical detection method executed by a processor (102) for controlling an optical detection device (1) that detects a reflected beam reflected from an irradiation beam scanned by a swing mirror (32), including: obtaining the actual angles of the swing mirror in the previous forward path cycle with respect to the start timing (t0) and the end timing (t1) of the forward path cycle in which the irradiation beam is scanned in the swing cycle of the swing mirror; correcting the start command angle and the end command angle, which are the respective control command angles of the swing mirror at the start timing and the end timing in the current forward path cycle, according to the angle deviation between the control command angle and the actual angle at the start timing and the end timing in the previous forward path cycle; controlling the angular velocity of the swing by variably setting the control command angle between the start command angle and the end command angle for each control timing obtained by dividing the period between the start timing and the end timing in the current forward path cycle; and setting the light emission timing of a light source (24) that generates the irradiation beam according to each amount of change in the setting of the actual angle in the current forward path cycle. An optical detection method.

9. An optical detection program stored in a storage medium (101) and including instructions to be executed by a processor (102) for controlling an optical detection device (1) that detects a reflected beam reflected from an irradiation beam scanned by a rocking mirror (32), wherein the instructions cause: obtaining, for a start point timing (t0) and an end point timing (t1) of an outgoing path period during which the irradiation beam is scanned, among the rocking periods of the rocking mirror, the actual angles of the rocking mirror in the previous outgoing path period; correcting, for the start point command angle and the end point command angle, which are the respective control command angles of the rocking mirror at the start point timing and the end point timing in the current outgoing path period, according to the angular deviation between the control command angles and the actual angles at the start point timing and the end point timing in the previous outgoing path period; controlling the angular velocity of rocking by variably setting the control command angle between the start point command angle and the end point command angle for each control timing obtained by dividing the period between the start point timing and the end point timing in the current outgoing path period; and setting the light emission timing of a light source (24) that generates the irradiation beam according to each amount of change in the setting of the actual angle in the current outgoing path period.

Images