Target detection device

Abstract

To provide a target detection device that enables distance measurement of highly reflective objects. [Solution] The emission unit 2 emits a beam formed by light generated by the light source 1, scanning the measurement range 30. The detection unit 3 measures the distance to targets 18 and 19 using signals obtained by photoelectric conversion of reflected light reflected by targets 18 and 19. The high-reflectivity object determination unit 4 determines whether the signal obtained by photoelectric conversion of reflected light exceeds the dynamic range of the detection unit 3. The intensity adjustment units 2 and 7 can adjust the intensity of the beam formed by light generated by the same light source 1. If the high-reflectivity object determination unit 4 determines that the signal obtained by photoelectric conversion of reflected light received from a predetermined direction exceeds the dynamic range of the detection unit 3, the remeasurement control units 5 and 6 control the emission unit 2 to emit a low-intensity beam, whose intensity has been reduced by the intensity adjustment units 2 and 7, in a predetermined direction to perform a remeasurement.

Description

Technical Field

[0001] The present disclosure relates to a target detection device for detecting a target object.

Background Art

[0002] Conventionally, as a target detection device for detecting a target object, for example, LiDAR is known. LiDAR is an abbreviation for Light Detection and Ranging or Laser Imaging Detection and Ranging. The target detection device repeatedly executes scanning of a frame by a beam with a measurement range from a start azimuth of measurement to an end azimuth of measurement as one frame, and measures the azimuth, distance, etc. of the target object by receiving and analyzing the reflected light reflected by the target object existing in the measurement range.

[0003] The LiDAR described in Patent Document 1 executes control to stop emitting a beam in a predetermined azimuth when receiving reflected light reflected from a highly reflective object such as a retroreflector from a predetermined azimuth. Thereby, this LiDAR prevents the reflected light received in the scanning of the next frame from being saturated and becoming noise. Also, Patent Document 1 describes adding a secondary light emitter (i.e., a light source of a different system) and a diffuser lens in addition to a primary light emitter (i.e., a light source of the main system) for detecting a target object.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the LiDAR described in Patent Document 1 stops emitting a beam in a predetermined direction where highly reflective objects are present, making it impossible to measure the distance to highly reflective objects. Furthermore, if the light source is turned off when the beam emission is stopped, a recovery time is required when the light source is turned on again. Moreover, as in Patent Document 1, adding a secondary light emitter and a diffuser lens in addition to the primary light emitter that detects the target increases the number of parts and costs.

[0006] In view of the above points, this disclosure aims to provide a target detection device that enables distance measurement of highly reflective objects. [Means for solving the problem]

[0007] According to one aspect of this disclosure, a target detection device for detecting targets (18, 19) is: A light source (1) that generates light, An emission unit (2) emits a beam formed by light generated by a light source, so as to scan the measurement range (30), A detection unit (3) that measures the distance to a target using a signal obtained by photoelectrically converting the reflected light reflected from the target, A high-reflectivity object determination unit (4) determines whether the signal obtained by photoelectric conversion of reflected light exceeds the dynamic range of the detection unit, An intensity adjustment unit (2, 7) that can adjust the intensity of the beam formed by light generated from the same light source, The system includes a remeasurement control unit (5, 6) that, when the high-reflectivity object determination unit determines that the signal obtained by photoelectric conversion of reflected light received from a predetermined direction exceeds the dynamic range of the detection unit, controls the emission unit to emit a low-intensity beam with reduced intensity by the intensity adjustment unit in a predetermined direction and perform a remeasurement.

[0008] According to this, during remeasurement, the emission unit emits a low-intensity beam in a predetermined direction to perform the remeasurement. Therefore, during remeasurement, the signal obtained by photoelectric conversion of the reflected light reflected at the predetermined direction is prevented from exceeding the dynamic range of the detection unit. Consequently, this target detection device can measure the distance of highly reflective objects that reflect high-intensity reflected light. Furthermore, since this target detection device uses light generated from the same light source to form a low-intensity beam with an intensity adjustment unit, the light source remains in the ON state and does not turn off as in Patent Document 1, thus eliminating the need for a light source recovery time. Therefore, this target detection device can improve the distance measurement rate (i.e., the speed and frequency of distance measurement) compared to Patent Document 1. Furthermore, since this intensity adjustment unit forms a low-intensity beam using light generated from the same light source, there is no need to add a separate light source system as in Patent Document 1. Therefore, this target detection device can reduce the number of parts and cost compared to Patent Document 1.

[0009] The reference numerals in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described later. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of the target detection device according to the first embodiment. [Figure 2] This is a schematic diagram of the optical IC included in the target detection device according to the first embodiment. [Figure 3] This is an explanatory diagram illustrating the measurement within a single frame by the target detection device according to the first embodiment. [Figure 4] This is an explanatory diagram, following Figure 3, to illustrate the measurements within a single frame. [Figure 5] This is a flowchart illustrating the control process for measurement by the target detection device according to the first embodiment. [Figure 6] This table illustrates the control process for measurement by the target detection device according to the first embodiment. [Figure 7] This table explains the control process for measurement using the comparative example target detection device. [Figure 8] This is an explanatory diagram illustrating the measurement within a single frame by the comparative example target detection device. [Figure 9]FIG. 3 is an explanatory diagram for explaining the measurement within one frame by the target detection device according to the first embodiment when there is a high reflector different from FIG. 3. [Figure 10] FIG. 3 is a flowchart for explaining the control process of the measurement by the target detection device according to the second embodiment. [Figure 11] FIG. 6 is an explanatory diagram for explaining the measurement within one frame by the target detection device according to the second embodiment. [Figure 12] FIG. 11 is an explanatory diagram for explaining the measurement within one frame following FIG. 11. [Figure 13] FIG. 12 is an explanatory diagram for explaining the measurement within one frame in a modification of the second embodiment. [Figure 14] FIG. 15 is an explanatory diagram for explaining the measurement within one frame following FIG. 13. [Figure 15] Table 18 is a table for explaining the control process of the measurement by the target detection device according to the third embodiment. [Figure 16] Table 21 is a table for explaining the control process of the measurement by the target detection device according to the fourth embodiment. [Figure 17] Table 24 is a table for explaining the control process of the measurement by the target detection device according to the fifth embodiment. [Figure 18] FIG. 27 is an explanatory diagram for explaining the measurement within one frame by the target detection device according to the sixth embodiment. [Figure 19] FIG. 30 is an explanatory diagram for explaining the measurement within one frame by the target detection device according to the seventh embodiment. [Figure 20] FIG. 33 is an explanatory diagram for explaining the measurement within one frame by the target detection device according to the eighth embodiment. MODE FOR CARRYING OUT THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals, and the description thereof will be omitted.

[0012] (First Embodiment) As an example of a target detection device in the first embodiment, a LiDAR mounted on a vehicle will be described. LiDAR is a sensor that emits an infrared beam and measures the direction, distance, etc., of a target from the reflected light reflected by the target. LiDAR is also called laser radar. The target detection device in the first embodiment can detect various objects such as vehicles and pedestrians, as well as highly reflective objects such as retroreflectors. A highly reflective object refers to a target that reflects highly intense reflected light.

[0013] As shown in Figure 1, the target detection device comprises a light source 1, an optical IC 2 (i.e., an optical integrated circuit), a detection unit 3, a high-reflectivity object determination unit 4, an orientation control unit 5, a phase calculation unit 6, and a phase control unit 7. The optical IC 2 functions as an "emitting unit" that emits a beam. The optical IC 2 and the phase control unit 7 function as an "intensity adjustment unit" that adjusts the intensity of the beam. The orientation control unit 5 and the phase calculation unit 6 function as a "re-measurement control unit" that controls the re-measurement of high-reflectivity objects.

[0014] Light source 1 is controlled by light source control unit 8 and generates frequency-modulated continuous wave (i.e., FMCW) light (e.g., infrared light). FMCW stands for Frequency Modulated Continuous Wave. The FMCW method emits light (chirp) that is modulated so that its frequency increases over time. The light generated by light source 1 is amplified by optical amplifier 9 and incident on optical IC 2.

[0015] As shown in Figure 2, the optical IC2 constitutes an optical phased array 10 (hereinafter referred to as "OPA10"). OPA stands for Optical Phased Array. The OPA10 is a device that can freely control the direction and shape of the beam emitted from the optical IC2 without using mechanical parts such as movable mirrors.

[0016] The OPA10 comprises a light incidence section 11, a light distribution section 12, multiple optical waveguides 13, multiple phase adjustment sections 14, multiple optical antennas 15, etc., and is formed on a silicon substrate (not shown). Light is incident on the light incidence section 11 from a light source 1 via an optical amplifier 9. The light distribution section 12 distributes the light incident on the light incidence section 11 to multiple optical waveguides 13 arranged in an array. The multiple optical waveguides 13 guide the light distributed by the light distribution section 12 to multiple optical antennas 15 provided at the end of each of the multiple optical waveguides 13. Multiple phase adjustment sections 14 provided in the middle of each of the multiple optical waveguides 13 control the phase of the light passing through the multiple optical waveguides 13 by changing the refractive index of the optical waveguides 13. This light is emitted from the multiple optical antennas 15. The OPA10 controls the phase of light passing through multiple optical waveguides 13 using a phase adjustment unit 14, thereby emitting a beam 17 in any direction through diffraction and interference of light waves 16 emitted from multiple optical antennas 15. The OPA10 functions as an "emitting unit" and emits the beam 17 to scan a predetermined measurement range outside the vehicle.

[0017] The phase control unit 7 shown in Figure 1 controls the drive of the phase adjustment unit 14 of the OPA 10. The phase control unit 7 and the OPA 10 function as an "intensity adjustment unit," making it possible to adjust the orientation and intensity of the beam formed by light generated by the same light source 1. Specifically, the phase control unit 7 controls the drive of the phase adjustment unit 14 of the OPA 10, and by controlling the phase of light passing through multiple optical waveguides 13, the beam can be blurred by expanding the area perpendicular to the direction of beam propagation (i.e., beam diameter) to any direction and size, thereby reducing the beam intensity per unit volume. More specifically, the phase control unit 7 and the OPA 10 can broaden the beam diameter and blur the beam, thereby reducing the beam intensity per unit volume, through phase control including nonlinearization or randomization of the phase shift amount. Hereinafter, a beam with lower intensity than the beam formed in a normal measurement (i.e., the reference beam) will be referred to as a "low-intensity beam." The amount of decrease in intensity of the low-intensity beam relative to the intensity of the beam formed in a normal measurement (i.e., the reference beam) will be referred to as the "blurring amount."

[0018] As shown in Figure 1, the beam emitted from the optical IC2 is reflected by the target 18 and incident as reflected light on the detection unit 3 of the target detection device. The detection unit 3 includes, for example, an IQ detection unit 20, a photodiode 21, a transimpedance amplifier 22, an analog-to-digital converter 23, a fast Fourier transform unit 24, a CFAR 25, and a distance measuring unit 26. CFAR stands for Constant False Alarm Rate.

[0019] The reflected light incident on the detection unit 3 is converted photoelectrically by the photodiode 21 after undergoing IQ detection (i.e., quadrature detection). The photoelectrically converted electrical signal is converted to a digital electrical signal by the analog-to-digital converter 23 (hereinafter referred to as "ADC23") via the transimpedance amplifier 22, and then frequency-analyzed by the fast Fourier transform unit 24 (hereinafter referred to as "FFT24"). The peak value is extracted from the frequency-analyzed information by the CFAR 25. Information regarding this peak value is input to the distance measuring unit 26. The distance measuring unit 26 measures the distance of the target 18 based on this peak value. Note that the detection unit 3 cannot measure the distance of the target 18 if the electrical signal obtained by photoelectrically converting the reflected light reflected from the target 18 exceeds the dynamic range of the detection unit 3.

[0020] The digital electrical signal converted from analog to digital by the ADC23 and the information analyzed by frequency analysis using the FFT24 are also input to the high-reflectivity object detection unit 4. The high-reflectivity object detection unit 4 determines whether the electrical signal obtained by photoelectric conversion of reflected light received from a predetermined direction exceeds the dynamic range of the detection unit 3, using information on the peak intensity of the signal or the frequency width of the signal (e.g., full width at half maximum). This determination determines whether a high-reflectivity object that produces such reflected light exists in a predetermined direction within the measurement range. When the high-reflectivity object detection unit 4 determines that the signal obtained by photoelectric conversion of reflected light received from a predetermined direction exceeds the dynamic range of the detection unit 3 (i.e., when it determines that a high-reflectivity object exists in a predetermined direction), this information is transmitted to the direction control unit 5 and the phase calculation unit 6.

[0021] When the above information is transmitted from the high-reflectance object determination unit 4, the orientation control unit 5 and the phase calculation unit 6 execute control processing to remeasure the high-reflectance object located in the predetermined orientation. The orientation control unit 5 issues a command signal to the phase calculation unit 6 to emit a low-intensity beam from the optical IC 2 towards the orientation where the high-reflectance object is located and to remeasure that orientation. The phase calculation unit 6 performs a phase calculation for the orientation where the high-reflectance object is located and a phase calculation to realize the "blurring amount" of the low-intensity beam, so that the optical IC 2 emits a low-intensity beam toward the orientation where the high-reflectance object is located. The blurring amount is calculated based on the reflected light received from the predetermined orientation in the previous measurement, so that the electrical signal obtained by photoelectric conversion of the reflected light reflected at the predetermined orientation is within the dynamic range of the detection unit 3.

[0022] The calculation results from the phase calculation unit 6 are transmitted to the light source control unit 8 and the phase control unit 7. The light source control unit 8 controls the driving of the light source 1. The phase control unit 7 controls the driving of the phase adjustment unit 14 of the optical IC 2 so that the optical IC 2 emits a low-intensity beam with the amount of blur calculated by the phase calculation unit 6 in a predetermined direction (i.e., the direction in which the highly reflective object exists) and performs remeasurement of the highly reflective object.

[0023] Next, the control process by which the target detection device of the first embodiment performs remeasurement of highly reflective objects will be explained with reference to the explanatory diagrams in Figures 3 and 4, and the flowchart in Figure 5.

[0024] This control process is assumed to be executed while the vehicle equipped with the target detection device is in motion. In the flowchart and its description in Figure 5, steps are simply denoted as "S". This is also the case for the control processes described in the comparative examples and embodiments described later.

[0025] As shown in Figure 3, one frame is defined as one scan of the measurement range 30 by the target detection device from the starting direction A to the ending direction Z. Another term is a scan line when the target detection device scans in the same linear or curved direction within one frame. For the sake of explanation, Figure 3 shows five scan lines within one frame, which are referred to as lines a to e in order from the vertical direction of Figure 3 (i.e., from bottom to top of Figure 3).

[0026] The target detection device, for example, scans horizontally, taking the leftmost direction of line a as the starting direction A for one frame, and measures each scanning line in the order of line a to line e, and takes the rightmost direction of line e as the ending direction Z for one frame. Figure 3 shows the state of the target detection device during scanning from the starting direction A to the ending direction Z for one frame. Specifically, Figure 3 shows the state in which the target detection device has measured lines a to d in order from the starting direction A, and is now measuring the direction N of line e. A highly reflective object 19 is assumed to be present at direction N. Note that at the time shown in Figure 3, the directions N+1, N+2, N+3, and the ending direction Z have not been measured, and these directions are represented by dashed lines.

[0027] The flowchart in Figure 5 illustrates the control process for measurement from direction N to direction N+1. As shown in Figure 5, in S1, the target detection device emits a beam towards direction N at time M, and in S2, it receives the reflected light from the highly reflective object 19 present at direction N that was emitted at time M. Then, in S3, the target detection device uses the highly reflective object determination unit 4 to determine whether the signal obtained by photoelectric conversion of the reflected light exceeds the dynamic range of the detection unit 3. In S3, it is assumed that the highly reflective object determination unit 4 has determined that the signal obtained by photoelectric conversion of the reflected light received from direction N exceeds the dynamic range of the detection unit 3. That is, as shown in Figure 3, it is determined that there is a highly reflective object 19 at direction N. Then, in S4 in Figure 5, the target detection device uses the direction control unit 5 and the phase calculation unit 6 to calculate the amount of blurring of the low-intensity beam emitted in remeasurement and the phase of the direction in which the highly reflective object 19 is located.

[0028] Next, in S5, the target detection device emits a low-intensity beam towards direction N at time M+1 and performs a remeasurement of direction N. That is, as shown in Figure 4, a low-intensity beam is emitted towards the highly reflective object 19 located at direction N. The target detection device then receives the reflected light from the low-intensity beam emitted at time M+1 that was reflected at direction N and measures the distance to the highly reflective object 19 located at direction N.

[0029] Subsequently, in S6, the target detection device initializes the blur amount (i.e., returns the beam intensity to the intensity of the reference beam) and calculates the phase of the direction from which the beam will be emitted in the next measurement (i.e., direction N+1). Then, in S7, the target detection device emits the beam at direction N+1 at time M+2 and performs the measurement at direction N+1.

[0030] Next, the control process for measurement by the target detection device of the first embodiment will be explained with reference to the table in Figure 6. The table in Figure 6 shows the direction measured at each time in each frame, with the vertical axis being "frame" and the horizontal axis being "time". For the sake of explanation, each frame shows only the direction 1 to direction 6 of one line out of multiple lines. Also, time 1 to time 7 are different times in each frame.

[0031] As shown in Figure 6, the target detection device measures bearings 1 to 6 at times 1 to 6 during the scanning of frame 1.

[0032] Next, during the scanning of frame 2, the target detection device measures direction 1 at time 1 and direction 2 at time 2. At this time, if the target detection device determines that there is a highly reflective object 19 at direction 2 at time 2, it emits a low-intensity beam to direction 2 again at the next time 3 and remeasures direction 2. If the distance to the highly reflective part present at direction 2 can be measured in this remeasurement, direction 3 to direction 6 are measured from time 4 to time 7.

[0033] Next, the target detection device measures bearings 1 to 6 at times 1 to 6 during the scanning of frame 3. However, due to the movement of the vehicle on which the target detection device is mounted or the movement of the highly reflective object 19 itself, the highly reflective object 19 may not be detected during the scanning of frame 3.

[0034] Thus, the target detection device of the first embodiment performs a remeasurement promptly after determining a highly reflective object 19, enabling faster distance measurement of the highly reflective object 19 and improving the distance measurement rate. Furthermore, the target detection device of the first embodiment can adjust the amount of beam blurring (i.e., intensity) by phase control of the OPA 10, eliminating the need for additional parts and requiring no recovery time.

[0035] Here, in order to compare with the target detection device of the first embodiment, the control process for measurement by the target detection device of the comparative example will be explained with reference to the table in Figure 7 and the explanatory diagram in Figure 8. The target detection device of the comparative example corresponds to the LiDAR described in Patent Document 1.

[0036] The table in Figure 7 uses "frame" on the vertical axis and "azimuth" on the horizontal axis, with "ON" indicating that beams are emitted in each direction within each frame, and "OFF" indicating that beam emission is stopped. In the comparative example, the ON / OFF state of beam emission is controlled by turning the light source ON / OFF. For the sake of explanation, each frame shows the ON / OFF state for azimuths 1 to 6 of only one of the multiple lines.

[0037] As shown in Figure 7, the comparative example target detection device emits beams from azimuths 1 to 6 during the scanning of frame 1 and performs measurements. Next, during the scanning of frame 2, it also emits beams from azimuths 1 to 6 and performs measurements. Now, let's assume that the comparative example target detection device determines that a highly reflective object 19 exists at azimuth 2 during the scanning of frame 2. Specifically, during the scanning of frame 2, the comparative example target detection device cannot measure the distance to the highly reflective object 19 at azimuth 2 because the signal obtained by photoelectric conversion of the reflected light at azimuth 2 exceeds the dynamic range.

[0038] Next, the comparative example target detection device stops emitting a beam toward direction 2 during the scanning of frame 3. Specifically, after emitting a beam toward direction 1, the comparative example target detection device turns off the light source to stop emitting a beam toward direction 2, and then turns the light source back on for measurement of direction 3 and beyond, emitting beams toward direction 3 to direction 6 for measurement. Therefore, as shown in Figure 8, the comparative example target detection device cannot measure the distance to the highly reflective object 19 located in direction 2 even during the scanning of frame 3. Next, as shown in Figure 7, during the scanning of frame 4, it is assumed that the highly reflective object 19 no longer exists in direction 2 due to vehicle movement, etc., and beams are emitted toward direction 1 to direction 6 for measurement.

[0039] Thus, the comparative example's target detection device stops emitting a beam in the direction where the highly reflective object 19 is located in the next frame after determining the highly reflective object 19, making it impossible to measure the distance to the highly reflective object 19. Furthermore, the comparative example's target detection device turns off the light source 1 when it stops emitting the beam, so it requires time for the light source 1 to recover before it can be turned on again.

[0040] Compared to the target detection device of the comparative example described above, the target detection device of the first embodiment has the following configuration and the effects it provides. (1) In the first embodiment, if the high-reflectivity object determination unit 4 determines that the signal obtained by photoelectric conversion of reflected light received from a predetermined direction exceeds the dynamic range of the detection unit 3, the target detection device performs a remeasurement of the predetermined direction. In the remeasurement, the direction control unit 5 and the phase calculation unit 6 function as a remeasurement control unit, and the optical IC 2, as the emission unit, emits a low-intensity beam, whose intensity has been reduced by the phase control unit 7 as the intensity adjustment unit, in the predetermined direction. According to this, during remeasurement, the optical IC2 emits a low-intensity beam in a predetermined direction to perform the remeasurement. Therefore, during remeasurement, the signal obtained by photoelectric conversion of the reflected light reflected by the highly reflective object 19 is prevented from exceeding the dynamic range of the detection unit 3. Consequently, this target detection device can measure the distance to the highly reflective object 19. Furthermore, since this target detection device uses light generated by the same light source 1 to form a low-intensity beam with the phase control unit 7, the light source 1 remains in the ON state and does not need to be turned off as in the comparative example, thus eliminating the need for a light source recovery time. Therefore, this target detection device can improve the distance measurement rate compared to the comparative example. Furthermore, since this intensity adjustment unit forms a low-intensity beam using light generated by the same light source 1, there is no need to add a separate light source system as in Patent Document 1. Therefore, this target detection device can reduce the number of parts and cost compared to Patent Document 1.

[0041] (2) In the first embodiment, during remeasurement, the phase calculation unit 6 calculates the intensity of the low-intensity beam based on the reflected light received from a predetermined direction in the previous measurement, such that the signal obtained by photoelectric conversion of the reflected light reflected at a predetermined direction is within the dynamic range of the detection unit 3. According to this, the target detection device can quickly and reliably measure the distance to the highly reflective object 19 during remeasurement.

[0042] (3) In the first embodiment, during remeasurement, the orientation control unit 5 and the phase calculation unit 6 control the optical IC 2 to emit a low-intensity beam to a predetermined orientation before emitting a beam to the next orientation (e.g., orientation N+1) after the predetermined orientation (e.g., orientation N) in scanning within the same frame. According to this, when the target detection device determines that a highly reflective object 19 exists in a predetermined direction, it remeasures the predetermined direction before emitting a beam in the next direction, thereby enabling faster distance measurement of the highly reflective object 19 and improving the distance measurement rate.

[0043] (4) In the first embodiment, the light source 1 generates light using the FMCW method. However, in the FMCW method, as in Patent Document 1, stopping the light source requires time to stabilize the light source in order to restart measurement, which significantly reduces the distance measurement rate. In contrast, in the first embodiment, the phase control unit 7 forms a low-intensity beam using light generated by the same light source 1, so there is no need to stop the light source 1. Therefore, this target detection device can measure the distance to highly reflective objects 19 faster than Patent Document 1, and can improve the distance measurement rate.

[0044] (5) In the first embodiment, the optical IC2 as the emission unit is composed of the OPA10. When re-measuring the distance, the target detection device emits a low-intensity beam in a predetermined direction by phase control of the OPA10. According to this, the OPA10 can arbitrarily change the direction from which the beam is emitted by phase control using the phase adjustment unit 14, so that remeasurement can be performed at any timing. Therefore, this target detection device can improve the distance measurement rate. Furthermore, the phase control unit 7 can adjust the amount of beam blurring (i.e., beam intensity) by controlling the phase of the OPA 10, eliminating the need for additional components and requiring no recovery time. Therefore, this target detection device can be low-cost and improve the distance measurement rate.

[0045] (6) In the first embodiment, the phase control unit 7 can reduce the beam intensity by controlling the phase of the OPA 10 during remeasurement, thereby widening the area perpendicular to the direction of beam propagation to an arbitrary size and blurring the light. According to this method, changing the beam intensity does not require the addition of parts, and there is no recovery time. Therefore, this target detection device can be low-cost and improve the ranging rate.

[0046] (7) In the first embodiment, the phase control unit 7 can reduce the beam intensity by controlling the phase of the OPA 10 during remeasurement, thereby widening the area perpendicular to the beam propagation direction in any direction perpendicular to the beam propagation direction and blurring the light. According to this, the phase control unit 7 can change the shape of the beam in any direction perpendicular to the direction of propagation by controlling the phase of the OPA 10.

[0047] (8) In the first embodiment, the phase control unit 7 can adjust the area perpendicular to the beam propagation direction by phase control, which includes nonlinearization or randomization of the phase shift amount in the OPA 10, when remeasurement is performed. According to this, the phase control unit 7 can arbitrarily change the beam intensity by controlling the phase of the OPA 10.

[0048] Here, with reference to Figure 9, we will explain the case in which the highly reflective object 19 exists across multiple directions during measurement using the target detection device of the first embodiment.

[0049] As shown in Figure 9, the highly reflective object 19 is located across the direction L of line d and the direction N of line e within the measurement range 30. In this case, when the target detection device determines the presence of the highly reflective object 19 by measuring the direction L on line d, it emits a low-intensity beam to direction L again and remeasures direction L before measuring direction L+1. Similarly, when the target detection device determines the presence of the highly reflective object 19 by measuring the direction N on line e, it emits a low-intensity beam to direction N again and remeasures direction N before measuring direction N+1. Thus, the target detection device of the first embodiment can quickly measure the distance to the highly reflective object 19 even when the highly reflective object 19 is present across multiple directions, thereby improving the distance measurement rate.

[0050] (Second Embodiment) A second embodiment will now be described. The second embodiment is similar to the first embodiment in that a part of the control process for re-measuring the highly reflective object 19 has been modified, and other aspects are the same as the first embodiment. Therefore, only the parts that differ from the first embodiment will be described.

[0051] The control process by which the target detection device of the second embodiment performs remeasurement of the highly reflective object 19 will be described with reference to the flowchart in Figure 10 and the explanatory diagrams in Figures 11 and 12. The flowchart in Figure 10 illustrates, for example, the control process for measurement from direction N to direction N+2 shown in Figures 11 and 12.

[0052] As shown in Figure 10, in S11, the target detection device emits a beam towards direction N at time M, and in S12, receives reflected light from a highly reflective object 19 located at direction N that emitted the beam at time M. Then, in S13, the target detection device uses a highly reflective object determination unit 4 to determine whether the signal obtained by photoelectric conversion of the reflected light exceeds the dynamic range of the detection unit 3. In S13, it is determined that there is a highly reflective object 19 at direction N, and that the signal obtained by photoelectric conversion of the reflected light exceeds the dynamic range of the detection unit 3.

[0053] Then, in S14, the target detection device, using the direction control unit 5 and the phase calculation unit 6, calculates the amount of blurring of the low-intensity beam emitted during the remeasurement of direction N and the phase of the direction in which the highly reflective object 19 is located. While performing these calculations, the target detection device detects the time required for the calculations. In the following explanation, the calculation of the amount of blurring of the low-intensity beam emitted during remeasurement and the phase calculation of the direction in which the highly reflective object 19 exists are referred to as "remeasurement calculation," and the time required for this calculation is referred to as "remeasurement calculation time."

[0054] Furthermore, in S14, the target detection device performs a "re-measurement calculation for direction N" while simultaneously performing a time determination in S15. The time determination in S15 determines whether the "re-measurement calculation time for direction N" is longer than the time it takes for the optical IC2 to emit a beam in the next direction (i.e., direction N+1) and for the detection unit 3 to measure the distance of the target 18. In the following explanation, the time it takes for the optical IC2 to emit a beam in the next direction and for the detection unit 3 to measure the distance of the target 18 is referred to as the "measurement time for the next direction".

[0055] In the time determination in S15, if the calculation time for remeasurement of direction N is shorter than the measurement time for the next direction N+1, the target detection device proceeds to S20 and remeasures direction N.

[0056] In contrast, in the time determination in S15, if the "calculation time for remeasurement regarding direction N" is longer than the "measurement time for the next direction N+1", the target detection device proceeds to S16 while performing the "calculation for remeasurement regarding direction N" in S14, and proceeds with the measurement of direction N+1. That is, in S17, the target detection device emits a beam to direction N+1 at time M+1, and in S18, it receives the reflected light from the target 18 located at direction N+1 that was emitted at time M+1. Then, in S19, the target detection device uses the high-reflectivity object determination unit 4 to determine whether the signal obtained by photoelectric conversion of the reflected light exceeds the dynamic range of the detection unit 3. In S19, it is determined that the signal obtained by photoelectric conversion of the reflected light is within the dynamic range of the detection unit 3. That is, as shown in Figure 11, it is determined that there is no high-reflectivity object 19 at direction N+1. Furthermore, it is assumed that the calculation for remeasuring the direction N in S14 is completed before or simultaneously with the determination in S19. Then, the target detection device proceeds to S20.

[0057] In S20, the target detection device emits a low-intensity beam towards direction N at time M+2 and performs a remeasurement of direction N. That is, as shown in Figure 12, a low-intensity beam is emitted towards the highly reflective object 19 located at direction N. The target detection device then receives the reflected light from the low-intensity beam emitted at time M+2 that was reflected at direction N and measures the distance to the highly reflective object 19 located at direction N.

[0058] Next, in S21, the target detection device initializes the blur amount (i.e., returns the beam intensity to the intensity of the reference beam) and calculates the direction from which the beam will be emitted in the next measurement (i.e., direction N+2). Then, in S22, the target detection device emits a beam at direction N+2 at time M+3 and performs the measurement at direction N+2.

[0059] The target detection device of the second embodiment described above controls the device to perform a remeasurement of the predetermined direction after measuring the next direction or a subsequent direction if the "calculation time for remeasurement of a predetermined direction" is longer than the "measurement time for the next direction". According to this, the target detection device performs calculations for remeasurement regarding a predetermined direction, measures the next direction or subsequent directions, and then remeasures the predetermined direction. Therefore, the target detection device can effectively utilize the calculation time for remeasurement to advance the measurement of each direction within the frame, thereby improving the distance measurement rate.

[0060] Incidentally, target detection devices may use different scanning methods for the multiple axes that form the frame. For example, in Figures 11 and 12, which were referenced in the description of the second embodiment, the horizontal axis uses a scanning method based on phase control of the OPA10, and the vertical axis uses a scanning method based on wavelength control. In this case, the scanning method based on phase control of the OPA10 has a faster scanning speed than the scanning method based on wavelength control. That is, the horizontal axis becomes a fast axis with a high scanning speed, and the vertical axis becomes a slow axis with a slower scanning speed than the horizontal axis.

[0061] Therefore, the target detection device of the second embodiment controls the device to remeasure direction N within the scanning line where direction N exists (e.g., line e) if the "calculation time for remeasurement of direction N" is longer than the "measurement time for the next direction N+1". According to this, when a frame is formed using a fast axis with a high scanning speed and a slow axis with a low scanning speed, the measurement of the highly reflective object 19 can be made as fast as possible by performing the remeasurement of the highly reflective object 19 within the fast axis. In other words, the delay time required for remeasurement can be minimized.

[0062] (Modified version of the second embodiment) A modified example of the second embodiment will be described with reference to Figures 13 and 14. In a modified version of the second embodiment, the vertical axis uses a scanning method based on phase control of the OPA10, and the horizontal axis uses a scanning method based on wavelength control. In this case, the vertical axis is a fast axis with a high scanning speed, and the horizontal axis is a slow axis with a slower scanning speed than the vertical axis.

[0063] Therefore, in the modified version of the second embodiment, if the "calculation time for remeasurement regarding direction N" is longer than the "measurement time for the next direction N+1", the system is controlled to remeasure direction N within the scanning line (e.g., line g) in the direction of the vertical axis where direction N exists. Note that in Figures 13 and 14, since direction N is the last direction of line g, the remeasurement of direction N is performed within line g before proceeding to line h. According to this, even in the modified version of the second embodiment, the measurement of the highly reflective object 19 can be made as fast as possible by performing the remeasurement of the highly reflective object 19 within the fast axis. In other words, the delay time required for remeasurement can be minimized.

[0064] (Third embodiment) A third embodiment will now be described. The third embodiment is a modification of the control process for re-measuring the highly reflective object 19 compared to the first embodiment, etc., and is otherwise the same as the first embodiment, etc. Therefore, only the parts that differ from the first embodiment, etc. will be described.

[0065] The control process by which the target detection device of the third embodiment performs remeasurement of the highly reflective object 19 will be explained with reference to the table in Figure 15. The table in Figure 15 shows the events and the order of the measured directions in each frame, with the vertical axis representing "frames" and the horizontal axis representing "events" and "time-series display of the direction to be measured." For ease of explanation, each frame shows only the directions 1 to 6 of one of several lines. This is also the case for the tables in Figures 16 and 17, which will be referenced in the descriptions of the fourth and fifth embodiments later.

[0066] As shown in Figure 15, the target detection device measures the direction from azimuth 1 to azimuth 6 in the order of scanning frame 1. In frame 1, the highly reflective object 19 is not detected.

[0067] Next, the target detection device scans frame 2 and measures in the order of direction 1 and then direction 2. When the signal obtained by photoelectric conversion of the reflected light from direction 2 exceeds the dynamic range, it determines that there is a highly reflective object 19 at direction 2. The target detection device then calculates the blur amount and emits a low-intensity beam to direction 2 again to remeasure direction 2. However, even in this remeasurement, the signal obtained by photoelectric conversion of the reflected light exceeds the dynamic range, so it is assumed that the distance to the highly reflective object 19 at direction 2 could not be measured. In that case, the target detection device recalculates the blur amount based on the reflected light received in the remeasurement and emits a low-intensity beam to direction 2 again to remeasure direction 2 a second time. If the distance to the highly reflective part at direction 2 can be measured in this third remeasurement, the device measures in the order of direction 3 to direction 6.

[0068] Next, the target detection device scans frame 3, measuring in the order of bearing 1 to bearing 6. In frame 3, the highly reflective object 19 is not detected. In frame 4, the device measures in the order of bearing 1 to bearing 6. In frame 4, the highly reflective object 19 is also not detected. In frame 5, the device measures in the order of bearing 1 to bearing 6. In frame 5, the highly reflective object 19 is also not detected.

[0069] The target detection device of the third embodiment described above provides the following effects and benefits through its configuration. (1) In the third embodiment, when the target detection device determines that a highly reflective object 19 is present in a predetermined direction, it performs distance measurement again by scanning within the same frame. According to this, the target detection device performs remeasurement during scanning within a single frame, allowing for faster distance measurement of highly reflective objects 19 and improving the distance measurement rate.

[0070] (2) In the third embodiment, if the high-reflectivity object determination unit 4 determines that the signal obtained by photoelectric conversion of reflected light received from a predetermined direction during remeasurement exceeds the dynamic range of the detection unit 3, the target detection device performs a second remeasurement of the predetermined direction within the same frame. According to this, even if the target detection device fails to measure the distance of the highly reflective object 19 during a remeasurement, it can quickly and reliably measure the distance of the highly reflective object 19 by performing a second remeasurement within a single frame scan.

[0071] (3) In the third embodiment, the target detection device calculates the amount of blurring (i.e., the intensity of the low-intensity beam) in the re-measurement based on the reflected light received in the re-measurement, such that the signal obtained by photoelectric conversion of the reflected light reflected at a predetermined direction is within the dynamic range of the detection unit 3. According to this, in subsequent measurements, the distance to the highly reflective object 19 can be measured quickly and reliably.

[0072] (Fourth Embodiment) A fourth embodiment will now be described. The fourth embodiment is a modification of the control process for re-measuring the highly reflective object 19 compared to the second embodiment, etc., and is otherwise the same as the second embodiment, etc. Therefore, only the parts that differ from the second embodiment, etc. will be described.

[0073] The control process by which the target detection device of the fourth embodiment performs remeasurement of the highly reflective object 19 will be explained with reference to the table in Figure 16. As shown in Figure 16, the target detection device measures in the order of direction 1 to direction 6 during the scanning of frame 1. The highly reflective object 19 is not detected in frame 1.

[0074] Next, the target detection device scans frame 2 and measures direction 1 and then direction 2. When the signal obtained by photoelectric conversion of the reflected light from direction 2 exceeds the dynamic range, it determines that there is a highly reflective object 19 at direction 2. Then, the target detection device calculates the amount of blurring and the phase of the direction for remeasurement of direction 2 (hereinafter referred to as "remeasurement calculation for direction 2"), and determines whether the calculation time for remeasurement for direction 2 is longer than the time to measure direction 3. If the target detection device determines that the calculation time for remeasurement for direction 2 is longer than the time to measure direction 3, it performs the remeasurement calculation for direction 2 while measuring direction 3. If the remeasurement calculation for direction 2 is completed before or simultaneously with the completion of measurement for direction 3, the target detection device remeasures direction 2. However, even in this remeasurement, the signal obtained by photoelectric conversion of the reflected light exceeds the dynamic range, and it is determined that the distance to the highly reflective object 19 at direction 2 could not be measured. In that case, the target detection device calculates the amount of blurring and the phase of the direction for the re-measurement of direction 2 (hereinafter referred to as "re-measurement calculation for direction 2"), and determines whether the calculation time for the re-measurement of direction 2 is longer than the time for measuring direction 4. If the target detection device determines that the calculation time for the re-measurement of direction 2 is longer than the time for measuring direction 4, it measures direction 4 while performing the re-measurement calculation for direction 2. If the re-measurement calculation for direction 2 is completed before or simultaneously with the completion of the measurement of direction 4, the target detection device performs the re-measurement of direction 2. If the target detection device is able to measure the distance of the highly reflective area present in direction 2 during that re-measurement, it measures direction 5 and then direction 6 in that order.

[0075] Next, the target detection device scans frame 3, measuring in the order of bearing 1 to bearing 6. In frame 3, the highly reflective object 19 is not detected. In frame 4, the device measures in the order of bearing 1 to bearing 6. In frame 4, the highly reflective object 19 is also not detected. In frame 5, the device measures in the order of bearing 1 to bearing 6. In frame 5, the highly reflective object 19 is also not detected.

[0076] The target detection device of the fourth embodiment described above provides the following effects and benefits through its configuration. (1) In the fourth embodiment, if the target detection device determines that the amount of blurring and the time required for calculating the phase of the direction for remeasuring a predetermined direction where a highly reflective object 19 is located is longer than the time required to measure the next direction, it measures the next direction within the same frame and then remeasuring the predetermined direction. According to this method, by effectively using the amount of blurring and the time required for phase calculation of the direction for remeasurement of a predetermined direction where a highly reflective object 19 is located, the distance measurement rate can be improved because the measurement of the next direction is performed within the same frame, and then the highly reflective object 19 at the predetermined direction is remeasured.

[0077] (2) In the fourth embodiment, if the target detection device determines that the time for calculating the amount of blurring and the phase of the direction for re-measurement of a predetermined direction where a highly reflective object 19 is located is longer than the time for measuring the next direction, it measures the next direction in the same frame and then re-measures the predetermined direction. According to this method, by effectively using the amount of blurring and the time for calculating the phase of the direction for the re-measurement of a predetermined direction where a highly reflective object 19 is located, the measurement of the next direction is performed within the same frame, and then the highly reflective object 19 at the predetermined direction is re-measured, thereby improving the distance measurement rate.

[0078] (Fifth embodiment) Next, we will describe the fifth embodiment. The fifth embodiment is similar to the second embodiment and the like in the second embodiment, with only a part of the control process for re-measuring the highly reflective object 19 being modified. Therefore, only the parts that differ from the second embodiment and the like will be described.

[0079] The control process by which the target detection device of the fifth embodiment performs remeasurement of the highly reflective object 19 will be explained with reference to the table in Figure 17. As shown in Figure 17, the target detection device measures in the order of direction 1 to direction 6 during the scanning of frame 1. The highly reflective object 19 is not detected in frame 1.

[0080] Next, the target detection device, scanning frame 2, measures direction 1 and then direction 2. When the signal obtained by photoelectric conversion of the reflected light from direction 2 exceeds the dynamic range, it determines that there is a highly reflective object 19 at direction 2. Then, while calculating the remeasurement for direction 2, the target detection device determines whether the calculation time for the remeasurement for direction 2 is longer than the time to measure direction 3 and subsequent directions. If the target detection device determines that the calculation time for the remeasurement for direction 2 is longer than the time to measure direction 3 and subsequent directions, it performs the remeasurement calculation for direction 2 while measuring direction 3 and subsequent directions. Specifically, the target detection device measures direction 3 to direction 6. If the calculation for the remeasurement for direction 2 is completed before or simultaneously with the completion of the measurement of direction 6, the target detection device performs a remeasurement of direction 2. If the target detection device can measure the distance to the highly reflective part at direction 2 in that remeasurement, it proceeds to measure the next frame.

[0081] Next, the target detection device scans frame 3, measuring in the order of bearing 1 to bearing 6. In frame 3, the highly reflective object 19 is not detected. In frame 4, the device measures in the order of bearing 1 to bearing 6. In frame 4, the highly reflective object 19 is also not detected. In frame 5, the device measures in the order of bearing 1 to bearing 6. In frame 5, the highly reflective object 19 is also not detected.

[0082] The target detection device of the fifth embodiment described above has the following effects due to its configuration. (1) If the target detection device determines that the amount of blurring and the time required to calculate the phase of the direction for remeasuring a predetermined direction where a highly reflective object 19 is located is longer than the time required to measure the next direction and subsequent directions, it measures the next direction and subsequent directions within the same frame and then remeasuring the predetermined direction. According to this, the target detection device can improve the distance measurement rate by effectively using the time for blurring and calculating the phase of the direction for remeasurement of a predetermined direction where a highly reflective object 19 is located, and then measuring the next direction and subsequent directions within the same frame before remeasurement of the highly reflective object 19 at the predetermined direction.

[0083] In the fifth embodiment, if the target detection device determines that there is a highly reflective object 19 at direction 2 during the scanning of frame 2, it measures direction 3 to direction 6 within the same frame and then remeasures direction 2; however, it is not limited to this. If the target detection device determines that there is a highly reflective object 19 at direction 2 during the scanning of frame 2, it may remeasure direction 2 at any timing during the measurement of direction 3 to direction 6 within the same frame.

[0084] (Sixth to eighth embodiments) The sixth to eighth embodiments are similar to the first embodiment, etc., but with modifications to the scanning lines within the frame. Therefore, only the differences from the first embodiment, etc., will be described.

[0085] Figure 18 shows the movement trajectory of the target detection device of the sixth embodiment as it emits beams in each direction within a single frame. As shown in Figure 18, the target detection device of the sixth embodiment scans within a single frame, drawing multiple elliptical shapes from the starting direction A to the ending direction Z. The multiple elliptical shapes are arranged so that their major axes are radial.

[0086] Figure 18 illustrates the direction in which the presence of the highly reflective object 19 was detected, the direction in which remeasurement is initiated, and the direction in which a second remeasurement is initiated. The target detection device is not limited to the directions illustrated in the figure; it can initiate remeasurement and second remeasurement at any timing in the middle of the direction Z from the direction in which the presence of the highly reflective object 19 was detected to the end of the frame measurement. Therefore, the target detection device of the sixth embodiment can also measure the distance to the highly reflective object 19 with a short additional time, thereby improving the distance measurement rate.

[0087] Figure 19 shows the movement trajectory of the target detection device of the seventh embodiment as it emits beams in each direction within a single frame. As shown in Figure 19, the target detection device of the seventh embodiment scans within a single frame, drawing multiple sine curves from the starting direction A to the ending direction Z. The multiple sine curves are arranged with phase shifts. The target detection device can move to remeasurement and re-remeasurement at any timing between the direction where the presence of a highly reflective object 19 is determined and the ending direction Z of the frame. Therefore, the target detection device of the seventh embodiment can also measure the distance to a highly reflective object 19 with a short additional time, thereby improving the distance measurement rate.

[0088] Figure 20 shows the movement trajectory of the target detection device of the eighth embodiment as it emits beams in each direction within a single frame. As shown in Figure 20, the target detection device of the eighth embodiment scans within a single frame, drawing multiple circular shapes from the starting direction A to the ending direction Z. Each of the multiple circular shapes is arranged so that it has a different center point, diameter, curvature, etc. In this disclosure, the term "circular shape" is not limited to a circle, but includes shapes that approximate a circle.

[0089] Figure 20 illustrates the direction in which the presence of the highly reflective object 19 was determined, the direction in which remeasurement is initiated, and the direction in which a second remeasurement is initiated. The target detection device is not limited to the directions illustrated in the figure; it can initiate remeasurement and second remeasurement at any timing in the middle of the direction Z at the end of measurement of the frame, starting from the direction in which the presence of the highly reflective object 19 was determined. Therefore, the target detection device of the eighth embodiment can also measure the distance to the highly reflective object 19 with a short additional time, thereby improving the distance measurement rate.

[0090] (Other embodiments) (1) In each of the above embodiments, the light generated by the light source 1 was described as an FMCW method, but it is not limited to this, and for example, an amplitude-modulated continuous wave (AMCW) method or a pulsed light method may also be used. AMCW is an abbreviation for Amplitude Modulated Continuous Wave. Furthermore, the measurement method is not limited to the iToF method, which emits a continuous wave and calculates the distance from the phase shift of the reflected light according to the distance to the target 18, but may also be the dToF method, which emits a pulsed laser and calculates the distance from the time of transmission and reception of the light. iToF is an abbreviation for Indirect Time of Flight, and dToF is an abbreviation for Direct Time of Flight.

[0091] (2) In the above embodiments, the optical IC2 constituting the OPA10 was described as the emission unit, but the emission unit is not limited to this, and may be, for example, a mechanical method that rotates the LiDAR body, or a MEMS method that scans the beam using an electromagnetic MEMS mirror. MEMS is an abbreviation for Micro Electro Mechanical Systems.

[0092] (3) In each of the above embodiments, the direction of scan transition, the starting direction A of measurement, the ending direction Z of measurement, etc., were given as examples in the frame, but the scan direction can be freely changed in electronic scanning, for example, by setting the starting direction of measurement to near the center.

[0093] (4) In each of the above embodiments, a target detection device mounted on a vehicle has been described, but the target detection device is not limited to this and can be used for various purposes such as aircraft, drones, robots, smartphones, and surveying.

[0094] This disclosure is not limited to the embodiments described above, and modifications may be made as appropriate within the scope of the claims. Furthermore, the embodiments and parts thereof are not unrelated to each other and can be combined as appropriate, except in cases where the combination is clearly impossible. In addition, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where they are explicitly stated to be particularly essential or where they are clearly considered essential in principle. Furthermore, in the embodiments, when numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiments are mentioned, the embodiments are not limited to those specific numbers, except in cases where they are explicitly stated to be particularly essential or where they are clearly limited to a specific number in principle. Furthermore, when the shapes, positional relationships, etc., of the components, etc., are mentioned in the embodiments, the embodiments are not limited to those shapes, positional relationships, etc., except in cases where they are explicitly stated to be particularly essential or where they are clearly limited to a specific shape, positional relationship, etc., in principle.

[0095] The control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the control unit and its method described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium. The memory described above is a non-transitional tangible storage medium. When the computer program is executed, the control method corresponding to the computer program is executed.

[0096] (Perspective of this disclosure) The above disclosure can be understood from the following perspectives, for example. [First point of view] In a target detection device that detects targets (18, 19), A light source (1) that generates light, An emission unit (2) emits a beam formed by light generated by the aforementioned light source so as to scan the measurement range (30), A detection unit (3) that measures the distance to the target using a signal obtained by photoelectrically converting the reflected light reflected by the target, A high reflectivity determination unit (4) determines whether the signal obtained by photoelectric conversion of reflected light exceeds the dynamic range of the detection unit, An intensity adjustment unit (2, 7) capable of adjusting the intensity of the beam formed by light generated by the same light source, A target detection device comprising: a remeasurement control unit (5, 6) that, when the high-reflectance object determination unit determines that the signal obtained by photoelectric conversion of reflected light received from a predetermined direction exceeds the dynamic range of the detection unit, controls the emission unit to emit a low-intensity beam with reduced intensity by the intensity adjustment unit in the predetermined direction and perform a remeasurement. [Second perspective] In the remeasurement, the remeasurement control unit calculates the intensity of a low-intensity beam based on the reflected light received from the predetermined direction in the previous measurement, such that the signal obtained by photoelectric conversion of the reflected light reflected at the predetermined direction falls within the dynamic range of the detection unit, according to the first aspect of the target detection device. [Third perspective] One frame is defined as the emission unit scanning the measurement range once from the measurement start direction (A) to the measurement end direction (Z). In the remeasurement, the remeasurement control unit controls the emission unit to emit a low-intensity beam in the predetermined direction during scanning within the same frame, as described in the first or second aspect of the target detection device. [Fourth perspective] The target detection device according to any one of the first to third aspects, wherein, if the high-reflectivity object determination unit determines that the signal obtained by photoelectric conversion of reflected light received from the predetermined direction during the aforementioned remeasurement exceeds the dynamic range of the detection unit, the remeasurement control unit controls the emission unit to emit a low-intensity beam in the predetermined direction during scanning within the same frame to perform a second remeasurement. [Fifth perspective] In the aforementioned re-measurement, the re-measurement control unit calculates the intensity of the low-intensity beam based on the reflected light received in the re-measurement, such that the signal obtained by photoelectric conversion of the reflected light reflected at the predetermined direction falls within the dynamic range of the detection unit, according to the fourth aspect of the target detection device. [Sixth perspective] In the remeasurement, the remeasurement control unit controls the emission unit to emit a low-intensity beam to the predetermined direction before emitting a beam to the next direction after the predetermined direction in scanning within the same frame, the target detection device according to any one of the first to fifth aspects. [Seventh perspective] One frame is defined as the emission unit scanning the measurement range from the measurement start direction to the measurement end direction once, and one scan line is defined as the emission unit scanning in the same linear or curved direction within one frame. In the remeasurement, if the calculation time required for the remeasurement control unit to calculate the intensity of the low-intensity beam so that the signal obtained by photoelectric conversion of the reflected light reflected at the predetermined direction is within the dynamic range of the detection unit is longer than the time required for the emission unit to emit a beam at the direction following the predetermined direction in scanning within the same frame and for the detection unit to measure the distance of the target, the target detection device according to any one of the first to fifth aspects, wherein after measuring the next direction or a subsequent direction, the remeasurement control unit controls the emission unit to emit a low-intensity beam at the predetermined direction at any timing within the scanning line where the predetermined direction exists and perform the remeasurement. [Perspective 8] One frame is defined as the emission unit scanning the measurement range once from the measurement start direction to the measurement end direction. In the remeasurement, if the calculation time required for the remeasurement control unit to calculate the intensity of the low-intensity beam so that the signal obtained by photoelectric conversion of the reflected light reflected at the predetermined direction is within the dynamic range of the detection unit is longer than the time required for the emission unit to emit a beam to the direction following the predetermined direction in scanning within the same frame and for the detection unit to measure the distance of the target, the target detection device according to any one of the first to fifth aspects, wherein after measuring the next direction or a subsequent direction, the remeasurement control unit controls the emission unit to emit a low-intensity beam to the predetermined direction at any timing within the same frame and perform the remeasurement. [Perspective 9] The target detection device according to any one of the first to eighth views, wherein the light source generates light in a frequency-modulated continuous wave manner. [Perspective 10] The emission unit comprises a plurality of optical waveguides (13) that distribute and guide the light generated by the light source, and a phase adjustment unit (14) that controls the phase of the light emitted from the optical antennas (15) at the ends of the plurality of optical waveguides, and is composed of an optical phased array (10) that forms and scans a beam with the light waves emitted from the plurality of optical antennas. A target detection device according to any one of the first to ninth views, wherein in the remeasurement, a low-intensity beam is emitted in the predetermined direction by phase control of the optical phased array. [Perspective 11] The target detection device according to the tenth aspect, wherein the intensity adjustment unit can, during remeasurement, broaden the area perpendicular to the direction of beam propagation to an arbitrary size by phase control of the optical phased array, thereby blurring the light and reducing the beam intensity. [Perspective 12] The target detection device according to the tenth or eleventh aspect, wherein the intensity adjustment unit, during remeasurement, can reduce the beam intensity by widening the area perpendicular to the beam propagation direction in any direction perpendicular to the beam propagation direction by phase control of the optical phased array, thereby blurring the light. [Perspective 13] The target detection device according to any one of the 10th to 12th aspects, wherein the intensity adjustment unit can reduce the beam intensity by adjusting the area perpendicular to the beam propagation direction through phase control, which includes nonlinearization or randomization of the phase shift amount in the optical phased array, during the remeasurement. [Explanation of Symbols]

[0097] 1 light source 2 Optical IC (emission part, intensity adjustment part) 3. Detection Unit 4 Highly reflective object determination section 5. Direction Control Unit (Remeasurement Control Unit) 6. Remeasurement Control Unit (Remeasurement Control Unit) 7 Phase control unit (intensity adjustment unit) 18 Target 19 Highly reflective object (target) 30 Measurement range

Claims

1. In a target detection device that detects targets (18, 19), A light source (1) that generates light, An emission unit (2) emits a beam formed by the light generated by the aforementioned light source so as to scan the measurement range (30), A detection unit (3) that measures the distance to the target using a signal obtained by photoelectric conversion of the reflected light reflected by the target, A high reflectivity determination unit (4) determines whether the signal obtained by photoelectric conversion of reflected light exceeds the dynamic range of the detection unit, An intensity adjustment unit (2, 7) capable of adjusting the intensity of the beam formed by light generated by the same light source, A target detection device comprising: a remeasurement control unit (5, 6) that, when the high-reflectivity object determination unit determines that the signal obtained by photoelectric conversion of reflected light received from a predetermined direction exceeds the dynamic range of the detection unit, controls the emission unit to emit a low-intensity beam with reduced intensity by the intensity adjustment unit in the predetermined direction and perform a remeasurement.

2. In the remeasurement, the remeasurement control unit calculates the intensity of a low-intensity beam based on the reflected light received from the predetermined direction in the previous measurement, such that the signal obtained by photoelectric conversion of the reflected light reflected at the predetermined direction is within the dynamic range of the detection unit, as described in claim 1.

3. One frame is defined as the emission unit scanning the measurement range once from the measurement start direction (A) to the measurement end direction (Z). In the remeasurement, the remeasurement control unit controls the emission unit to emit a low-intensity beam in the predetermined direction during scanning within the same frame, as described in claim 1 or 2 of the target detection device.

4. If the high-reflectivity object determination unit determines that the signal obtained by photoelectric conversion of reflected light received from the predetermined direction during the remeasurement exceeds the dynamic range of the detection unit, the remeasurement control unit controls the emission unit to emit a low-intensity beam in the predetermined direction during scanning within the same frame to perform a second remeasurement, as described in claim 1 or 2.

5. In the aforementioned re-measurement, the re-measurement control unit calculates the intensity of a low-intensity beam based on the reflected light received in the re-measurement, such that the signal obtained by photoelectric conversion of the reflected light reflected at the predetermined direction is within the dynamic range of the detection unit, as described in claim 4.

6. In the remeasurement, the remeasurement control unit controls the emission unit to emit a low-intensity beam to the predetermined direction before emitting a beam to the next predetermined direction in scanning within the same frame, the target detection device according to claim 1 or 2.

7. One frame is defined as the emission unit scanning the measurement range from the measurement start direction to the measurement end direction once, and one scan line is defined as the emission unit scanning in the same linear or curved direction within one frame. In the remeasurement, if the calculation time required for the remeasurement control unit to calculate the intensity of the low-intensity beam so that the signal obtained by photoelectric conversion of the reflected light reflected at the predetermined direction is within the dynamic range of the detection unit is longer than the time required for the emission unit to emit a beam at the direction following the predetermined direction in scanning within the same frame and for the detection unit to measure the distance of the target, the target detection device according to claim 1 or 2, wherein after measuring the next direction or subsequent directions, the remeasurement control unit controls the emission unit to emit a low-intensity beam at the predetermined direction at any timing within the scanning line where the predetermined direction exists and perform the remeasurement.

8. One frame is defined as the emission unit scanning the measurement range once from the measurement start direction to the measurement end direction. In the remeasurement, if the calculation time required for the remeasurement control unit to calculate the intensity of the low-intensity beam so that the signal obtained by photoelectric conversion of the reflected light reflected at the predetermined direction is within the dynamic range of the detection unit is longer than the time required for the emission unit to emit a beam to the direction following the predetermined direction in scanning within the same frame and for the detection unit to measure the distance of the target, the target detection device according to claim 1 or 2, wherein after measuring the next direction or subsequent directions, the remeasurement control unit controls the emission unit to emit a low-intensity beam to the predetermined direction at any timing within the same frame and perform the remeasurement.

9. The target detection device according to claim 1 or 2, wherein the light source generates light in a frequency-modulated continuous wave manner.

10. The emission unit comprises a plurality of optical waveguides (13) that distribute and guide the light generated by the light source, and a phase adjustment unit (14) that controls the phase of the light emitted from the optical antennas (15) at the ends of the plurality of optical waveguides, and is composed of an optical phased array (10) that forms and scans a beam with the light waves emitted from the plurality of optical antennas. The target detection device according to claim 1 or 2, wherein in the remeasurement, a low-intensity beam is emitted in the predetermined direction by phase control of the optical phased array.

11. The target detection device according to claim 10, wherein the intensity adjustment unit can, during remeasurement, widen the area perpendicular to the direction of beam propagation to an arbitrary size by phase control of the optical phased array, thereby blurring the light and reducing the beam intensity.

12. The target detection device according to claim 10, wherein the intensity adjustment unit, during the remeasurement, can reduce the beam intensity by controlling the phase of the optical phased array to widen the area perpendicular to the beam propagation direction in any direction perpendicular to the beam propagation direction, thereby blurring the light.

13. The target detection device according to claim 10, wherein the intensity adjustment unit can reduce the beam intensity by adjusting the area perpendicular to the beam propagation direction through phase control, which includes nonlinearization or randomization of the phase shift amount in the optical phased array, during the remeasurement.

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