Target detection device

Abstract

In a target detection device, an emission unit (2) emits a beam formed by light generated by a light source (1) so as to scan a measurement range (30), and a detection unit (3) performs distance measurement of a target (18, 19) using a signal obtained by photoelectrically converting reflected light reflected by the target (18, 19). A highly reflective object determination unit (4) determines whether or not a signal obtained by photoelectric conversion of reflected light exceeds a dynamic range of a detection unit (3), and intensity adjustment units (2, 7) are capable of adjusting the intensity of a beam formed by light generated by the same light source (1). When a highly reflective object determination unit (4) determines that a signal obtained by photoelectrically converting reflected light received from a predetermined orientation exceeds a dynamic range of a detection unit (3), re-measurement control units (5, 6) perform re-measurement by causing an emission unit (2) to emit a low-intensity beam, the intensity of which has been reduced by intensity adjustment units (2, 7), in the predetermined orientation. And performing control.

Description

Object detection device Technical Field

[0001] This disclosure relates to an object detection device for detecting objects. Background Technology

[0002] Previously, LiDAR was known as a device for detecting objects. LiDAR is an abbreviation for Light Detection and Ranging or Laser Imaging Detection and Ranging. The object detection device takes a frame as the measurement range from the starting position to the ending position of the measurement, and repeatedly performs beam-based frame scans. It receives and analyzes the reflected light from objects present within the measurement range, thereby measuring the object's orientation, distance, etc.

[0003] The LiDAR described in Patent Document 1, for example, when receiving reflected light from a highly reflective object such as a retroreflector from a predetermined direction, executes control to stop emitting a beam towards that predetermined direction during the scanning of the next frame. This prevents the LiDAR from becoming noise due to saturation of the reflected light received in the next frame scan. Furthermore, Patent Document 1 describes the addition of a secondary light emitter (i.e., a light source for the main system) and a diffusion lens, in addition to the primary light emitter for target detection (i.e., the light source for the main system).

[0004] Prior art literature, patent literature, patent literature 1: Japanese Patent No. 7383815 Summary of the Invention

[0005] However, the LiDAR described in Patent Document 1 stops emitting a beam towards a predetermined location where highly reflective objects exist, thus making it impossible to measure the distance to highly reflective objects. Furthermore, if the light source is disconnected when beam emission stops, a recovery time is required when the light source is reconnected. Moreover, if, as in Patent Document 1, a secondary light emitter and a diffusion lens are added in addition to the primary light emitter for object detection, the number of components and the cost increase.

[0006] In view of the above-mentioned problems, the present disclosure aims to provide a target detection device capable of measuring the distance of highly reflective objects.

[0007] According to one aspect of this disclosure, a target detection apparatus for detecting targets includes: a light source that generates light; an emission unit that emits a beam of light generated by the light source in a scanning measurement range manner; a detection unit that uses a signal obtained by photoelectric conversion of reflected light reflected from a target to measure the distance of the target; a high reflectivity determination unit that determines whether the signal obtained by photoelectric conversion of reflected light exceeds the dynamic range of the detection unit; an intensity adjustment unit that can adjust the intensity of the beam of light generated by the same light source; and a remeasurement control unit that, when the high reflectivity 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 for remeasurement.

[0008] Therefore, during remeasurement, the emission unit emits a low-intensity beam in a predetermined direction to perform remeasurement. This prevents the signal obtained from photoelectric conversion of reflected light at the predetermined direction from exceeding the dynamic range of the detection unit. Thus, this target detection device can measure the distance to highly reflective objects with high reflectivity. Furthermore, this target detection device uses light generated from the same light source and forms a low-intensity beam through the intensity adjustment unit, so the light source is kept on, unlike Patent Document 1 where the light source is turned off, thus eliminating the need for light source recovery time. Therefore, compared to Patent Document 1, this target detection device can improve the ranging rate (i.e., the speed and frequency of ranging).

[0009] Furthermore, since the intensity adjustment unit forms a low-intensity beam using light generated from the same light source, it eliminates the need for additional light sources or other systems as required in Patent Document 1. Therefore, this object detection device reduces the number of components and lowers costs compared to Patent Document 1. Attached Figure Description

[0010] Figure 1 is a schematic structural diagram of the object detection device according to the first embodiment.

[0011] Figure 2 is a schematic structural diagram of the optical IC included in the object detection device of the first embodiment.

[0012] Figure 3 is an explanatory diagram illustrating an intra-frame measurement performed by the object detection device of the first embodiment.

[0013] Figure 4 is an illustration of the measurement within a frame following Figure 3.

[0014] Figure 5 is a flowchart illustrating the control process of the measurement performed by the object detection device of the first embodiment.

[0015] Figure 6 is a table illustrating the control processing of measurements performed by the object detection device according to the first embodiment.

[0016] Figure 7 is a table illustrating the control processing of the measurement performed by the object detection device in the comparative example.

[0017] Figure 8 is an explanatory diagram of an intra-frame measurement performed by the object detection device for the comparative example.

[0018] Figure 9 is an explanatory diagram illustrating an intra-frame measurement performed by the object detection device of the first embodiment when a highly reflective object different from that in Figure 3 is present.

[0019] Figure 10 is a flowchart illustrating the control process of the measurement performed by the object detection device according to the second embodiment.

[0020] Figure 11 is an explanatory diagram illustrating an intra-frame measurement performed by the object detection device according to the second embodiment.

[0021] Figure 12 is an explanatory diagram illustrating the measurement within a frame following Figure 11.

[0022] Figure 13 is an explanatory diagram illustrating the measurement within a frame in a modified example of the second embodiment.

[0023] Figure 14 is an explanatory diagram for illustrating measurements within a frame following Figure 13.

[0024] Figure 15 is a table illustrating the control processing of measurements performed by the object detection device according to the third embodiment.

[0025] Figure 16 is a table illustrating the control processing of measurements performed by the object detection device according to the fourth embodiment.

[0026] Figure 17 is a table illustrating the control processing of measurements performed by the object detection device according to the fifth embodiment.

[0027] Figure 18 is an explanatory diagram illustrating an intra-frame measurement performed by the object detection device according to the sixth embodiment.

[0028] Figure 19 is an explanatory diagram illustrating an intra-frame measurement performed by the object detection device according to the seventh embodiment.

[0029] Figure 20 is an explanatory diagram illustrating an intra-frame measurement performed by the object detection device according to the eighth embodiment. Detailed Implementation

[0030] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Furthermore, in the following embodiments, the same reference numerals will be used to label the same or equivalent parts, and their descriptions will be omitted.

[0031] (First Embodiment) As an object detection device according to the first embodiment, a LiDAR mounted on a vehicle will be described, for example. A LiDAR is a sensor that emits an infrared beam and measures the orientation, distance, etc., of an object based on the reflected light reflected by the object. LiDAR is also known as lidar. In addition to detecting various objects such as vehicles and pedestrians, the object detection device of the first embodiment can also detect highly reflective objects such as retroreflectors. Furthermore, highly reflective objects refer to objects that reflect light with high intensity.

[0032] As shown in Figure 1, the object detection device includes a light source 1, an optical IC 2 (i.e., an optical integrated circuit), a detection unit 3, a high reflectivity determination unit 4, an orientation control unit 5, a phase calculation unit 6, and a phase control unit 7. Furthermore, the optical IC 2 functions as an "emission unit" for emitting a beam. Additionally, the optical IC 2 and the phase control unit 7 function as an "intensity adjustment unit" for adjusting the intensity of the beam. The orientation control unit 5 and the phase calculation unit 6 function as a "remeasurement control unit" for controlling the remeasurement of high reflectivity objects.

[0033] The driving of light source 1 is controlled by light source control unit 8, generating light (e.g., infrared light) in a frequency modulated continuous wave (FMCW) mode. FMCW is an abbreviation for Frequency Modulated Continuous Wave. FMCW mode emits light whose frequency is modulated (chirp) by increasing over time. The light generated by light source 1 is amplified by optical amplifier 9 and incident on optical IC2.

[0034] As shown in Figure 2, the optical IC2 constitutes an optical phased array 10 (hereinafter referred to as "OPA10"). OPA is an abbreviation for Optical Phased Array. OPA10 is a device that can freely control the orientation and shape of the beam emitted from the optical IC2 without using mechanical parts such as movable mirrors.

[0035] The OPA10 comprises a light incident section 11, a light distribution section 12, multiple optical waveguides 13, multiple phase adjustment sections 14, and multiple optical antennas 15, formed on a silicon substrate (not shown). Light from a light source 1 is incident on the light incident section 11 via an optical amplifier 9. The light distribution section 12 distributes the light incident on the light incident section 11 to the multiple optical waveguides 13 arranged in an array. The multiple optical waveguides 13 guide the light distributed by the light distribution section 12 to the multiple optical antennas 15 disposed at the front end of each of the multiple optical waveguides 13. The multiple phase adjustment sections 14 disposed at 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. The light is emitted from the multiple optical antennas 15. By controlling the phase of the light passing through the multiple optical waveguides 13 with the phase adjustment section 14, the OPA10 can emit a beam 17 in any direction by utilizing the diffraction and interference of the light wave 16 emitted from the multiple optical antennas 15. OPA10 functions as an "ejector" to emit beam 17 in a manner that scans a specified measurement range outside the vehicle.

[0036] The phase control unit 7 shown in Figure 1 controls the driving 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," capable of adjusting the orientation and intensity of the beam formed by light generated from the same light source 1. Specifically, the phase control unit 7 controls the driving of the phase adjustment unit 14 of the OPA 10, utilizing phase control of light passing through multiple optical waveguides 13 to expand the area of ​​the beam perpendicular to the direction of travel (i.e., the beam diameter) to an arbitrary direction and size, thereby blurring the beam and reducing the intensity of the beam per unit volume. More specifically, the phase control unit 7 and the OPA 10, through nonlinear or randomized phase control including phase shift, can expand the beam diameter to blur the beam and reduce the intensity of the beam per unit volume. Hereinafter, a beam with reduced intensity compared to a beam formed by normal measurement (i.e., a reference beam) will be referred to as a "low-intensity beam." In addition, the amount of reduction in intensity of a low-intensity beam relative to the intensity of the beam formed in a normal measurement (i.e., the reference beam) is called the "ambiguity amount".

[0037] 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 detector 20, a photodiode 21, a trans-impedance amplifier 22, an analog-to-digital converter 23, a fast Fourier transform unit 24, a CFAR 25, and a ranging unit 26. Furthermore, CFAR is an abbreviation for Constant False Alarm Rate.

[0038] The reflected light incident on the detection unit 3 is processed by IQ detection (i.e., quadrature detection) and then photoelectrically converted by photodiode 21. The photoelectrically converted electrical signal is then converted into a digital electrical signal by analog-to-digital converter 23 (hereinafter referred to as "ADC23") via transimpedance amplifier 22, and then frequency-analyzed by fast Fourier transform unit 24 (hereinafter referred to as "FFT24"). The peak value is extracted by CFAR 25 after frequency analysis. Information related to this peak value is input to ranging unit 26. Ranging unit 26 performs ranging of target 18 based on this peak value. Furthermore, if the electrical signal obtained by photoelectric conversion of the reflected light from target 18 exceeds the dynamic range of detection unit 3, detection unit 3 cannot perform ranging of target 18.

[0039] The digital electrical signal obtained after analog-to-digital conversion by ADC23 and the information obtained after frequency analysis by FFT24 are also input to the high reflectivity determination unit 4. The high reflectivity determination unit 4 uses information about the peak intensity of the signal or the frequency width of the signal (e.g., half-width) to determine whether the electrical signal obtained by photoelectric conversion of reflected light received from a specified orientation exceeds the dynamic range of the detection unit 3. This determination determines whether a high reflectivity that generates such reflected light exists at a specified orientation within the measurement range. The high reflectivity determination unit 4 is, for example, composed of a comparator. If the high reflectivity determination unit 4 determines that the signal obtained by photoelectric conversion of reflected light received from a specified orientation exceeds the dynamic range of the detection unit 3 (i.e., if it is determined that a high reflectivity exists at a specified orientation), this information is transmitted to the orientation control unit 5 and the phase calculation unit 6.

[0040] When the aforementioned information is transmitted from the high reflectivity determination unit 4, the orientation control unit 5 and the phase calculation unit 6 perform control processing to remeasure the high reflectivity present at the specified orientation. The orientation control unit 5 sends a command signal to the phase calculation unit 6 to emit a low-intensity beam from the optical IC2 toward the orientation where the high reflectivity exists and to remeasure that orientation. The phase calculation unit 6 performs phase calculation for the orientation where the high reflectivity exists and phase calculation for the "ambiguity amount" used to realize the low-intensity beam, so that the optical IC2 emits a low-intensity beam toward the orientation where the high reflectivity exists. The ambiguity amount is calculated based on the reflected light received from the specified orientation in the previous measurement, so that the electrical signal obtained by photoelectric conversion of the reflected light reflected at the specified orientation is within the dynamic range of the detection unit 3.

[0041] 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 light IC2, so that the light IC2 emits a low-intensity beam with the ambiguity calculated by the phase calculation unit 6 in a predetermined direction (i.e., the direction where a highly reflective object exists), and performs a remeasurement of the highly reflective object.

[0042] Next, the control process for re-measuring highly reflective objects by the object detection device of the first embodiment will be described with reference to the explanatory diagrams of FIG3 and FIG4 and the flowchart of FIG5.

[0043] This control process is performed while the vehicle equipped with the object detection device is in motion. Furthermore, in the flowchart and description of Figure 5, the steps are simply denoted as "S". This is also the case in the control processes described in the comparative examples and embodiments described later.

[0044] As shown in Figure 3, scanning the measurement range 30 once by the object detection device from the starting position A to the ending position Z is called a frame. Furthermore, scanning in the same straight or curved direction within a frame is called a scan line. In Figure 3, for ease of explanation, five scan lines are shown within a frame, and they are sequentially named lines a through e along the vertical direction of Figure 3 (i.e., from bottom to top).

[0045] The object detection device, for example, scans and measures horizontally from the leftmost position of line a as the starting position A of a measurement frame, and similarly scans and measures each scan line in the order of lines a to e, taking the rightmost position of line e as the ending position Z of a measurement frame. Figure 3 shows the state of the object detection device scanning from the starting position A of a measurement frame to the ending position Z. Specifically, Figure 3 shows the state of the object detection device measuring the position N of line e after sequentially measuring lines a to d from the starting position A. Assume that a highly reflective object 19 exists at position N. Furthermore, at the time shown in Figure 3, measurements are not performed at positions N+1, N+2, N+3, and the ending position Z; these positions are indicated by dashed lines.

[0046] Figure 5 illustrates the control processing for the measurement from azimuth N to azimuth N+1. As shown in Figure 5, in S1, the target detection device emits a beam towards azimuth N at time M. In S2, it receives the reflected light from the beam emitted at time M after it has been reflected by a highly reflective object 19 present at azimuth N. Then, in S3, the target detection device determines, by the highly reflective object determination unit 4, 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 determines that the signal obtained by photoelectric conversion of the reflected light received from azimuth N exceeds the dynamic range of the detection unit 3. That is, as shown in Figure 3, it is determined that a highly reflective object 19 exists at azimuth N. Therefore, in S4 of Figure 5, the target detection device calculates the ambiguity of the low-intensity beam emitted during the remeasurement and the phase of the azimuth of the highly reflective object 19 using the azimuth control unit 5 and the phase calculation unit 6.

[0047] Next, in S5, the target detection device emits a low-intensity beam towards azimuth N at time M+1 to perform a remeasurement of azimuth N. That is, as shown in FIG4, a low-intensity beam is emitted towards the highly reflective object 19 present at azimuth N. Then, the target detection device receives the reflected light from the low-intensity beam emitted at time M+1 after reflection at azimuth N, and performs distance measurement on the highly reflective object 19 present at azimuth N.

[0048] Then, in S6, the target detection device initializes the ambiguity (i.e., returns the beam intensity to the intensity of the reference beam) and performs phase calculation for the azimuth of the emitted beam (i.e., azimuth N+1) in the subsequent measurement. Then, in S7, the target detection device emits a beam towards azimuth N+1 at time M+2 and performs the measurement of azimuth N+1.

[0049] Next, the control processing of the target detection device of the first embodiment will be described with reference to the table in FIG6. In FIG6, the vertical axis is designated as "frame" and the horizontal axis as "time", indicating the orientation measured at each time in each frame. In addition, for ease of explanation, only the orientation 1 to orientation 6 of one of the multiple lines is shown in each frame. Furthermore, time 1 to time 7 are different times in each frame.

[0050] As shown in Figure 6, the object detection device measures orientation 1 to orientation 6 at time 1 to time 6 during the scanning of frame 1.

[0051] Next, during the scanning of frame 2, the target detection device measures azimuth 1 at time 1 and azimuth 2 at time 2. If the target detection device determines at time 2 that a highly reflective object 19 exists at azimuth 2, it will fire a low-intensity beam towards azimuth 2 again at the next time 3 to remeasure azimuth 2. When the remeasurement allows for ranging of the highly reflective object 19 present at azimuth 2, azimuths 3 to 6 are measured at times 4 to 7.

[0052] Next, during the scan of frame 3, the object detection device measures orientation 1 to orientation 6 at times 1 to 6. Furthermore, due to the movement of the vehicle equipped with the object detection device or the movement of the highly reflective object 19 itself, the highly reflective object 19 is not detected during the scan of frame 3.

[0053] Thus, the object detection device of the first embodiment quickly performs a remeasurement after determining the highly reflective object 19, thereby enabling rapid ranging of the highly reflective object 19 and improving the ranging rate. In addition, the object detection device of the first embodiment can adjust the amount of ambiguity (i.e., intensity) of the beam through the phase control of the OPA10, so no additional components are required and no recovery time is needed.

[0054] Here, in order to compare with the object detection device of the first embodiment, the control processing for measurement of the comparative example object detection device will be described with reference to the table in FIG7 and the explanatory diagram in FIG8. Furthermore, the comparative example object detection device corresponds to the LiDAR described in Patent Document 1.

[0055] The table in Figure 7 uses the vertical axis as "frame" and the horizontal axis as "azimuth". In each frame, the state of emitting beams in each direction is marked as ON (emitting), and the state of stopping beam emission is marked as OFF (stopped). In the comparative example, the ON and OFF of beam emission are controlled by turning the light source on and off. Furthermore, for ease of explanation, only the ON and OFF of azimuth 1 to azimuth 6 of one line out of multiple lines is shown in each frame.

[0056] As shown in Figure 7, the comparative example's target detection device emits a beam to azimuths 1 to 6 during the scan of frame 1. Then, during the scan of frame 2, it also emits a beam to azimuths 1 to 6 for measurement. Here, the comparative example's target detection device determines that a highly reflective object 19 exists at azimuth 2 midway through the scan of frame 2. Specifically, during the scan of frame 2, the comparative example's target detection device obtains a signal from the photoelectric conversion of the reflected light at azimuth 2 that exceeds its dynamic range, thus making it unable to measure the distance to the highly reflective object 19 present at azimuth 2.

[0057] Next, the comparative example's target detection device stops emitting a beam toward azimuth 2 midway through the scan of frame 3. Specifically, after emitting a beam toward azimuth 1, the comparative example's target detection device disconnects the light source and stops emitting a beam toward azimuth 2. Then, in order to perform measurements in azimuth 3 and beyond, it reconnects the light source and emits beams toward azimuths 3 through 6 to perform measurements. Therefore, as shown in FIG8, the comparative example's target detection device is unable to measure the distance of the highly reflective object 19 present in azimuth 2 even during the scan of frame 3. Next, as shown in FIG7, during the scan of frame 4, assuming that the highly reflective object 19 is absent in azimuth 2 due to vehicle movement, etc., beams are emitted toward azimuths 1 through 6 and measurements are performed.

[0058] Thus, after determining that the highly reflective object 19 exists, the comparative example's object detection device stops firing the beam toward the location where the highly reflective object 19 exists in the next frame, and therefore cannot perform distance measurement of the highly reflective object 19. In addition, the comparative example's object detection device disconnects the light source 1 when it stops firing the beam, so a recovery time is required for the light source 1 when it is turned on again.

[0059] Compared to the object detection device in the comparative example described above, the object detection device of the first embodiment has the following structure and the resulting effect. When the high reflectivity 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 object detection device of the first embodiment performs a remeasurement of that predetermined direction. During the remeasurement, the orientation control unit 5 and the phase calculation unit 6 function as a remeasurement control unit, and the light IC2, acting as the emission unit, emits a low-intensity beam with reduced intensity by the phase control unit 7, which acts as the intensity adjustment unit, towards the predetermined direction. Thus, during the remeasurement, the light IC2 emits a low-intensity beam towards the predetermined direction for remeasurement. Therefore, during the remeasurement, the signal obtained by photoelectric conversion of reflected light reflected from the high reflectivity object 19 is prevented from exceeding the dynamic range of the detection unit 3. Therefore, this object detection device is capable of measuring the distance to the high reflectivity object 19. Furthermore, this target detection device uses light generated by the same light source 1 to form a low-intensity beam via the phase control unit 7. Therefore, the light source 1 is kept on, unlike the comparative example where the light source is turned off, thus eliminating the need for a light source recovery time. Consequently, this target detection device can improve the ranging rate compared to the comparative example. Moreover, since the intensity adjustment unit uses light generated by the same light source 1 to form a low-intensity beam, it eliminates the need for additional light sources or other systems as described in Patent Document 1. Therefore, this target detection device reduces the number of components and lowers costs compared to Patent Document 1.

[0060] 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 orientation in the previous measurement, so that the signal obtained by photoelectric conversion of the reflected light reflected from the predetermined orientation is within the dynamic range of the detection unit 3. Therefore, the target detection device can quickly and reliably measure the distance to the highly reflective object 19 during remeasurement.

[0061] In the first embodiment, during remeasurement, the orientation control unit 5 and the phase calculation unit 6 control the emission of a low-intensity beam to the specified orientation before emitting a beam to the next orientation (e.g., orientation N+1) within the same frame scan of the optical IC2. Therefore, when the target detection device determines that a highly reflective object 19 exists at the specified orientation, it performs a remeasurement of the specified orientation before emitting a beam to the next orientation, thus enabling rapid ranging of the highly reflective object 19 and improving the ranging rate.

[0062] In the first embodiment, the light source 1 generates light in an FMCW (Free-Measuring-Wave) manner. However, in the FMCW manner, if the light source is stopped as in Patent Document 1, the light source needs time to stabilize before measurement can resume, resulting in a significant decrease in the ranging 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, thus eliminating the need to stop the light source 1. Therefore, compared to Patent Document 1, this target detection device can quickly measure the distance to highly reflective objects 19, thereby improving the ranging rate.

[0063] In the first embodiment, the light IC2, which serves as the emission section, is composed of an OPA10. During re-ranging, the target detection device emits a low-intensity beam in a predetermined direction via phase control of the OPA10. Therefore, the OPA10 can arbitrarily change the direction of the emitted beam through phase control by the phase adjustment unit 14, enabling re-ranging at any given time. Thus, this target detection device can improve the ranging rate. Furthermore, the phase control unit 7 can adjust the beam ambiguity (i.e., beam intensity) through phase control of the OPA10, eliminating the need for additional components and recovery time. Therefore, this target detection device achieves low cost and improved ranging rate.

[0064] In the first embodiment, during remeasurement, the phase control unit 7 expands the area of ​​the beam perpendicular to the direction of travel to an arbitrary size by controlling the phase of the OPA10, thereby blurring the light and reducing the beam intensity. Therefore, no additional components or recovery time are required when changing the beam intensity. Thus, this target detection device achieves low cost and improves ranging speed.

[0065] In the first embodiment, during remeasurement, the phase control unit 7, through phase control of the OPA10, expands the area of ​​the beam perpendicular to the direction of travel in any direction perpendicular to the direction of travel, thereby blurring the light and reducing the intensity of the beam. Thus, the phase control unit 7, through phase control of the OPA10, can change the shape of the beam to any direction perpendicular to the direction of travel.

[0066] In the first embodiment, during remeasurement, the phase control unit 7 can adjust the area of ​​the beam perpendicular to the direction of travel by means of nonlinear or randomized phase control including phase shift in the OPA10. Therefore, the phase control unit 7 can arbitrarily change the intensity of the beam by means of phase control in the OPA10.

[0067] Here, the case where a highly reflective object 19 exists across multiple orientations during the measurement of the object detection device in the first embodiment will be described with reference to FIG9.

[0068] As shown in Figure 9, the highly reflective object 19 exists across the azimuth L of line d and the azimuth N of line e within the measurement range 30. In this case, if the object detection device determines the presence of the highly reflective object 19 in line d by measuring azimuth L, it fires a low-intensity beam again towards azimuth L before performing the measurement at azimuth L+1, and performs a remeasurement of azimuth L. Similarly, if the object detection device determines the presence of the highly reflective object 19 by measuring azimuth N of line e, it fires a low-intensity beam again towards azimuth N before performing the measurement at azimuth N+1, and performs a remeasurement of azimuth N. Thus, even when the highly reflective object 19 exists across multiple azimuths, the object detection device of the first embodiment can quickly measure the distance to the highly reflective object 19, thereby improving the ranging rate.

[0069] (Second Embodiment) The second embodiment will be described. The second embodiment differs from the first embodiment in that a portion of the control process for re-measuring the highly reflective material 19 is changed; otherwise, it is the same as the first embodiment. Therefore, only the parts that differ from the first embodiment will be described.

[0070] Referring to the flowchart in FIG10 and the explanatory diagrams in FIGS11 and 12, the control process for re-measuring the highly reflective object 19 in the object detection apparatus of the second embodiment will be described. The flowchart in FIG10 illustrates, for example, the control process for measuring from azimuth N to azimuth N+2 as shown in FIG11 and 12.

[0071] As shown in Figure 10, in step S11, the target detection device emits a beam towards orientation N at time M. In step S12, it receives the reflected light obtained by the beam emitted at time M being reflected by a highly reflective object 19 located at orientation N. Then, in step S13, the target detection device determines, via the highly reflective object determination unit 4, whether the signal obtained by photoelectric conversion of the reflected light exceeds the dynamic range of the detection unit 3. In step S13, assuming that a highly reflective object 19 exists at orientation N, it is determined that the signal obtained by photoelectric conversion of the reflected light exceeds the dynamic range of the detection unit 3.

[0072] Therefore, in S14, the target detection device, through the orientation control unit 5 and the phase calculation unit 6, performs calculations on the ambiguity of the low-intensity beam emitted during the remeasurement of orientation N and the phase of the orientation where the highly reflective object 19 exists. The target detection device performs this calculation and detects the time required for the calculation. In the following description, the calculation of the ambiguity of the low-intensity beam emitted during the remeasurement and the phase of the orientation where the highly reflective object 19 exists will be referred to as the "remeasurement calculation," and the time required for this calculation will be referred to as the "remeasurement calculation time."

[0073] Furthermore, the object detection device performs a "remeasurement calculation related to orientation N" in S14 and a time determination in S15. The time determination in S15 determines whether the "remeasurement calculation time related to orientation N" is longer than the time it takes for the light IC2 to emit a beam in the downward direction (i.e., orientation N+1) and for the detection unit 3 to measure the distance to the object 18. In the following explanation, the time it takes for the light IC2 to emit a beam in the downward direction and for the detection unit 3 to measure the distance to the object 18 is referred to as the "measurement time in the next direction".

[0074] In the time determination in S15, if the "calculation time for remeasurement related to azimuth N" is shorter than the "measurement time for the next azimuth N+1", the object detection device causes the processing to proceed to S20 to perform remeasurement of azimuth N.

[0075] In contrast, during the time determination in S15, if the "calculation time for remeasurement related to azimuth N" is longer than the "measurement time for the next azimuth N+1", the target detection device performs the "calculation for remeasurement related to azimuth N" in S14, and moves the processing to S16 to proceed to the measurement of azimuth N+1. That is, in S17, the target detection device emits a beam towards azimuth N+1 at time M+1, and in S18, it receives the reflected light obtained by the beam emitted towards azimuth N+1 at time M+1 being reflected by the target 18 present in azimuth N+1. Furthermore, in S19, the target detection device determines, through the high reflectivity determination unit 4, 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 FIG11, it is determined that there is no high reflectivity 19 in azimuth N+1. Furthermore, it is assumed that the calculation of the remeasurement of orientation N in S14 ends before or simultaneously with the determination in S19. Therefore, the object detection device moves the processing to S20.

[0076] In S20, the target detection device emits a low-intensity beam towards azimuth N at time M+2, performing a remeasurement of azimuth N. That is, as shown in FIG12, a low-intensity beam is emitted towards the highly reflective object 19 present at azimuth N. Furthermore, the target detection device receives the reflected light obtained by the low-intensity beam emitted at time M+2 reflected at azimuth N, and performs distance measurement on the highly reflective object 19 present at azimuth N.

[0077] Next, in S21, the target detection device initializes the ambiguity (i.e., returns the beam intensity to the intensity of the reference beam) and calculates the azimuth of the emitted beam (i.e., azimuth N+2) in the subsequent measurement. Then, in S22, the target detection device emits a beam toward azimuth N+2 at time M+3 and performs the measurement of azimuth N+2.

[0078] The object detection device of the second embodiment described above controls the remeasurement of the specified orientation after measuring the next orientation or a subsequent orientation, when the calculation time for the remeasurement related to the specified orientation is longer than the measurement time for the next orientation. Thus, the object detection device performs the calculation for the remeasurement related to the specified orientation, measures the next orientation or a subsequent orientation, and then performs the remeasurement of the specified orientation. Therefore, the object detection device can effectively utilize the remeasurement calculation time to advance the measurement of each orientation within the frame, thereby improving the ranging rate.

[0079] However, for object detection devices, sometimes the scanning methods for the multiple axes forming a frame are different. For example, in Figures 11 and 12 referred to in the description of the second embodiment, the horizontal axis is a scanning method based on phase control of OPA10, and the vertical axis is a scanning method based on wavelength control. In this case, the scanning method based on phase control of OPA10 has a faster scanning speed than the scanning method based on wavelength control. That is, the horizontal axis is the fast axis with a faster scanning speed, and the vertical axis is the slow axis with a slower scanning speed than the horizontal axis.

[0080] Therefore, in the second embodiment, when the calculation time for remeasurement related to orientation N is longer than the measurement time for the next orientation N+1, the object detection device is controlled to remeasure orientation N using the scan line (e.g., line e) where orientation N is located. Thus, when frames are formed with a fast axis (fast scanning speed) and a slow axis (slow scanning speed), the measurement of the highly reflective object 19 can be maximized by remeasuring it within the fast axis. In other words, the delay time required for remeasurement can be minimized.

[0081] (Modifications of the Second Embodiment) A modification of the second embodiment will be described with reference to FIGS. 13 and 14. In the modification of the second embodiment, the vertical axis is a scanning mode based on phase control of OPA10, and the horizontal axis is a scanning mode based on wavelength control. In this case, the vertical axis becomes a fast axis with a fast scanning speed, and the horizontal axis becomes a slow axis with a slower scanning speed than the vertical axis.

[0082] Therefore, in a variation of the second embodiment, when the calculation time for the remeasurement related to azimuth N is longer than the measurement time for the next azimuth N+1, control is implemented by remeasuring azimuth N in a scan line (e.g., line g) along the direction of the vertical axis where azimuth N is located. Furthermore, in Figures 13 and 14, azimuth N becomes the final azimuth of line g, so the remeasurement of azimuth N is performed on line g before entering line h. Thus, in this variation of the second embodiment, by remeasuring the highly reflective material 19 within the fast axis, the measurement of the highly reflective material 19 can be maximized. In other words, the delay time required for remeasurement can be minimized.

[0083] (Third Embodiment) The third embodiment will be described. The third embodiment changes a part of the control process for re-measuring the highly reflective material 19 compared to the first embodiment, etc., but is otherwise the same as the first embodiment, etc., so only the parts that are different from the first embodiment, etc. will be described.

[0084] Referring to the table in FIG15, the control process for re-measuring the highly reflective object 19 in the object detection apparatus of the third embodiment will be described. The table in FIG15 uses "frame" for the vertical axis and "event" and "time sequence display of measured orientation" for the horizontal axis, showing the order of events and measured orientations in each frame. For ease of explanation, only the orientations 1 to 6 of one of the multiple lines are shown in each frame. Furthermore, this is also the case in the tables of FIG16 and FIG17 referred to in the descriptions of the fourth and fifth embodiments described later.

[0085] As shown in Figure 15, the object detection device performs measurements in the order of orientation 1 to orientation 6 during the scan of frame 1. No highly reflective object 19 was detected in frame 1.

[0086] Next, when measurements are performed in azimuth 1 and azimuth 2 during the scan of frame 2, the signal obtained by photoelectric conversion of the reflected light from azimuth 2 exceeds the dynamic range. Therefore, the object detection device determines that a highly reflective object 19 exists in azimuth 2. The object detection device then calculates the ambiguity and fires a low-intensity beam towards azimuth 2 again for remeasurement. However, in this remeasurement, because the signal obtained by photoelectric conversion of the reflected light exceeds the dynamic range, ranging of the highly reflective object 19 in azimuth 2 cannot be performed. In this case, the object detection device calculates the ambiguity again based on the reflected light received in the remeasurement, fires a low-intensity beam towards azimuth 2 again, and performs another remeasurement of azimuth 2. When ranging of the highly reflective object 19 in azimuth 2 can be performed through this second remeasurement, measurements are performed in azimuth 3 to azimuth 6 in sequence.

[0087] Next, the object detection device performed measurements in the order of orientation 1 to orientation 6 during the scan of frame 3. No highly reflective object 19 was detected in frame 3. Measurements were then performed in the order of orientation 1 to orientation 6 during the scan of frame 4. No highly reflective object 19 was detected in frame 4 either. Measurements were then performed in the order of orientation 1 to orientation 6 during the scan of frame 5. No highly reflective object 19 was detected in frame 5 either.

[0088] The object detection device of the third embodiment described above achieves the following structural effects. In the third embodiment, when the object detection device determines that a highly reflective object 19 is present at a specified location, it performs a re-range measurement by scanning within the same frame. Therefore, since the object detection device performs a re-measurement by scanning within one frame, it can quickly measure the distance to the highly reflective object 19, thereby improving the ranging rate.

[0089] In the third embodiment, if the high reflectivity determination unit 4 determines that the signal obtained by photoelectric conversion of the reflected light received from the predetermined orientation during remeasurement exceeds the dynamic range of the detection unit 3, the target detection device performs a remeasurement of the predetermined orientation within the same frame scan. Therefore, even if the target detection device cannot measure the distance of the high reflectivity 19 during remeasurement, it can quickly and reliably measure the distance of the high reflectivity 19 by performing a remeasurement within a single frame scan.

[0090] In the third embodiment, during the remeasurement, the object detection device calculates the ambiguity (i.e., the intensity of the low-intensity beam) based on the reflected light received during the remeasurement, so that the signal obtained by photoelectric conversion of the reflected light reflected at a specified orientation is within the dynamic range of the detection unit 3. Therefore, during the remeasurement, the highly reflective object 19 can be measured quickly and reliably.

[0091] (Fourth Embodiment) The fourth embodiment will be described. The fourth embodiment differs from the second embodiment in that a portion of the control process for re-measuring the highly reflective material 19 is changed, while the rest is the same as the second embodiment. Therefore, only the parts that are different from the second embodiment will be described.

[0092] The control process for re-measuring the highly reflective object 19 in the object detection device of the fourth embodiment will be described with reference to the table in FIG16. As shown in FIG16, the object detection device performs measurements in the order of orientation 1 to orientation 6 during the scan of frame 1. In frame 1, the highly reflective object 19 is not detected.

[0093] Next, when measurements are performed sequentially in azimuth 1 and azimuth 2 during the scan of frame 2, the signal obtained by photoelectric conversion of the reflected light from azimuth 2 exceeds the dynamic range. Therefore, the object detection device determines that a highly reflective object 19 exists in azimuth 2. The object detection device then performs ambiguity calculations for the remeasurement of azimuth 2 and the phase calculation of the azimuth (hereinafter referred to as "azimuth 2-related remeasurement calculation"), and determines whether the calculation time for the azimuth 2-related remeasurement is longer than the measurement time for azimuth 3. If it is determined that the calculation time for the azimuth 2-related remeasurement is longer than the measurement time for azimuth 3, the object detection device performs the azimuth 2-related remeasurement calculation and measures azimuth 3. If the azimuth 2-related remeasurement calculation ends before or simultaneously with the end of the azimuth 3 measurement, the object detection device performs a remeasurement of azimuth 2. However, in this remeasurement, since the signal obtained by photoelectric conversion of the reflected light exceeds the dynamic range, ranging of the highly reflective object 19 present in azimuth 2 cannot be performed. In this case, the object detection device performs ambiguity calculations for the remeasurement of azimuth 2 and the phase calculation of the azimuth (hereinafter referred to as "remeasurement calculation related to azimuth 2"), and determines whether the calculation time for the remeasurement related to azimuth 2 is longer than the time for measuring azimuth 4. If it is determined that the calculation time for the remeasurement related to azimuth 2 is longer than the time for measuring azimuth 4, the object detection device performs the remeasurement calculation related to azimuth 2 and measures azimuth 4. If the remeasurement calculation related to azimuth 2 ends before or simultaneously with the end of the measurement of azimuth 4, the object detection device performs a remeasurement of azimuth 2. When the object detection device can measure the distance of the highly reflective object 19 present in azimuth 2 through this remeasurement, it performs the measurements in the order of azimuth 5 and azimuth 6.

[0094] Next, the object detection device performed measurements in the order of orientation 1 to orientation 6 during the scan of frame 3. No highly reflective object 19 was detected in frame 3. Measurements were then performed in the order of orientation 1 to orientation 6 during the scan of frame 4. No highly reflective object 19 was detected in frame 4 either. Measurements were then performed in the order of orientation 1 to orientation 6 during the scan of frame 5. No highly reflective object 19 was detected in frame 5 either.

[0095] The object detection device of the fourth embodiment described above achieves the following structural effects. In the fourth embodiment, if the object detection device determines that the ambiguity of the remeasurement of the predetermined orientation of the highly reflective object 19 and the time for calculating the phase of the orientation are longer than the time for measuring the next orientation, then the predetermined orientation is remeasured after measuring the next orientation within the same frame. Therefore, by effectively utilizing the ambiguity of the remeasurement of the predetermined orientation of the highly reflective object 19 and the time for calculating the phase of the orientation, the remeasurement of the highly reflective object 19 at the predetermined orientation is performed after measuring the next orientation within the same frame, thus improving the ranging rate.

[0096] In the fourth embodiment, if the target detection device determines that the time for calculating the ambiguity and phase of the azimuth for re-measuring the specified azimuth of the highly reflective object 19 is longer than the time for measuring the next azimuth, then it performs a re-measuring of the specified azimuth after measuring the next azimuth within the same frame. Therefore, by effectively utilizing the time for calculating the ambiguity and phase of the azimuth for re-measuring the specified azimuth of the highly reflective object 19, and performing a re-measuring of the highly reflective object 19 at the specified azimuth after measuring the next azimuth within the same frame, the ranging rate can be improved.

[0097] (Fifth Embodiment) The fifth embodiment will be described. The fifth embodiment is different from the second embodiment, etc., in that the control process for re-measuring the highly reflective material 19 is changed, but otherwise it is the same as the second embodiment, etc. Therefore, only the parts that are different from the second embodiment, etc. will be described.

[0098] The control process for re-measuring the highly reflective object 19 in the object detection device of the fifth embodiment will be described with reference to the table in FIG17. As shown in FIG17, the object detection device performs measurements in the order of orientation 1 to orientation 6 during the scan of frame 1. In frame 1, the highly reflective object 19 is not detected.

[0099] Next, when measurements are performed sequentially in azimuth 1 and azimuth 2 during the scan of frame 2, the signal obtained by photoelectric conversion of the reflected light from azimuth 2 exceeds the dynamic range. Therefore, the object detection device determines that a highly reflective object 19 exists in azimuth 2. The object detection device then performs a remeasurement calculation related to azimuth 2 and determines whether the calculation time for the remeasurement related to azimuth 2 is longer than the time for measuring azimuth 3 and subsequent azimuths. If the object detection device determines that the calculation time for the remeasurement related to azimuth 2 is longer than the time for measuring azimuth 3 and subsequent azimuths, it performs the remeasurement calculation related to azimuth 2 and measures azimuth 3 and subsequent azimuths. Specifically, the object detection device measures azimuths 3 through azimuth 6. If the remeasurement calculation related to azimuth 2 ends before or simultaneously with the end of the measurement of azimuth 6, the object detection device performs a remeasurement of azimuth 2. When the object detection device can measure the distance to the highly reflective object 19 present in azimuth 2 through this remeasurement, it proceeds to the next frame measurement.

[0100] Next, the object detection device performed measurements in the order of orientation 1 to orientation 6 during the scan of frame 3. No highly reflective object 19 was detected in frame 3. Measurements were then performed in the order of orientation 1 to orientation 6 during the scan of frame 4. No highly reflective object 19 was detected in frame 4 either. Measurements were then performed in the order of orientation 1 to orientation 6 during the scan of frame 5. No highly reflective object 19 was detected in frame 5 either.

[0101] The object detection device of the fifth embodiment described above achieves the following structural effects. If the object detection device determines that the time for calculating the ambiguity and phase of the remeasurement of the predetermined orientation of the highly reflective object 19 is longer than the time for measuring the next and subsequent orientations, it performs a remeasurement of the predetermined orientation after measuring the next and subsequent orientations within the same frame. Therefore, the object detection device effectively utilizes the time for calculating the ambiguity and phase of the remeasurement of the predetermined orientation of the highly reflective object 19, and performs a remeasurement of the highly reflective object 19 at the predetermined orientation after measuring the next and subsequent orientations within the same frame, thus improving the ranging rate.

[0102] Furthermore, in the fifth embodiment, if the object detection device determines that a highly reflective object 19 exists at orientation 2 during the scanning of frame 2, it performs a remeasurement of orientation 2 after measuring orientations 3 to 6 within the same frame, but is not limited to this. Alternatively, if the object detection device determines that a highly reflective object 19 exists at orientation 2 during the scanning of frame 2, it performs a remeasurement of orientation 2 at any time during the measurement of orientations 3 to 6 within the same frame.

[0103] (Sixth to Eighth Embodiments) The sixth to eighth embodiments differ from the first embodiment and the like in that the scan lines within the frame are changed, but otherwise they are the same as the first embodiment and the like. Therefore, only the parts that are different from the first embodiment and the like will be described.

[0104] Figure 18 shows the trajectory of the target detection device of the sixth embodiment as it emits beams in all directions within a frame. As shown in Figure 18, the target detection device of the sixth embodiment scans from the measurement start position A to the measurement end position Z within a frame in a manner that depicts multiple elliptical shapes. The multiple elliptical shapes are arranged with their major axes radiating outwards.

[0105] Figure 18 illustrates the location where a highly reflective object 19 is determined to exist, the location for remeasurement, and the location for further remeasurement. Furthermore, the object detection device is not limited to the location shown in the figure, but can move to the remeasurement location and then remeasure again at any time interval from the location where the highly reflective object 19 is determined to exist to the location Z at the end of the measurement in the frame. Therefore, the object detection device of the sixth embodiment can also measure the distance to the highly reflective object 19 with a shorter additional time, thereby improving the ranging rate.

[0106] Figure 19 shows the trajectory of the object detection device of the seventh embodiment as it emits beams in all directions within a frame. As shown in Figure 19, the object detection device of the seventh embodiment scans from the measurement start position A to the measurement end position Z within a frame, drawing multiple sine curves. The multiple sine curves are arranged with staggered phases. The object detection device can move from the position where a highly reflective object 19 is determined to exist, to the midpoint of the measurement end position Z of the frame, and then remeasure and remeasure again at arbitrary timing. Therefore, the object detection device of the seventh embodiment can also measure the distance of the highly reflective object 19 with a shorter additional time, thereby improving the ranging rate.

[0107] Figure 20 shows the trajectory of the target detection device of the eighth embodiment as it emits beams in all directions within a frame. As shown in Figure 20, the target detection device of the eighth embodiment scans from the measurement start position A to the measurement end position Z within a frame in a manner that depicts multiple circular shapes. The multiple circular shapes are arranged in different ways, such as with respect to the center point, diameter, and curvature. Furthermore, in this disclosure, the circular shape is not limited to a circle, but includes shapes that approximate a circle.

[0108] Figure 20 illustrates the location where a highly reflective object 19 is determined to exist, the location for remeasurement, and the location for further remeasurement. Furthermore, the object detection device is not limited to the locations illustrated in the figure; it can move from the location where a highly reflective object 19 is determined to exist, to the location Z where the frame measurement ends, and to the location for remeasurement and further remeasurement at any time interval. Therefore, the object detection device of the eighth embodiment can also measure the distance to the highly reflective object 19 with a shorter additional time, thereby improving the ranging rate.

[0109] (Other Embodiments) In the embodiments described above, the light generated by the light source 1 was described as an FMCW method, but it is not limited to this. For example, it could also be an Amplitude Modulated Continuous Wave (AMCW) method or a pulsed light method. AMCW is an abbreviation for Amplitude Modulated Continuous Wave. Furthermore, the measurement method is not limited to the so-called iToF method, which calculates the distance based on the phase shift of the reflected light corresponding to the distance to the target 18 by emitting a continuous wave. It could also be the so-called dToF method, which calculates the distance based on the time of light transmission and reception by emitting a pulsed laser. Additionally, iToF is an abbreviation for Indirect Time of Flight, and dToF is an abbreviation for Direct Time of Flight.

[0110] In the above embodiments, the optical IC2 constituting OPA10 is described as the emission unit, but it is not limited to this. The emission unit may also be a mechanical means of rotating the LiDAR body, or a MEMS means of scanning the beam using an electromagnetic MEMS mirror. In addition, MEMS is an abbreviation for Micro Electro Mechanical Systems.

[0111] In the above embodiments, the scanning direction, the measurement start position A, and the measurement end position Z are illustrated in the frame, but it is not limited to these. For example, the center area can be set as the measurement start position, and the scanning position can be freely changed during electronic scanning.

[0112] In the above embodiments, an object detection device mounted on a vehicle has been described, but it is not limited thereto. The object detection device can be used for various purposes such as airplanes, drones, robots, smartphones, and measurement.

[0113] This disclosure is not limited to the embodiments described above, and appropriate modifications can be made within the scope of the claims. Furthermore, the various embodiments and parts thereof described above are not mutually exclusive and can be appropriately combined, except in cases where they are clearly incompatible. Additionally, in the various embodiments described above, the elements constituting the embodiment are not necessarily essential, except where they are specifically stated to be necessary or where they are clearly considered necessary in principle. Furthermore, in the various embodiments described above, when referring to the number, value, quantity, range, etc., of the constituent elements of the embodiment, the number is not limited to that specific number, except where it is specifically stated to be necessary or where it is clearly limited to a specific number in principle. Furthermore, in the various embodiments described above, when referring to the shape, positional relationship, etc., of the constituent elements, the shape, positional relationship, etc., is not limited to that shape, positional relationship, etc., except where it is specifically stated or where it is limited to a specific shape, positional relationship in principle.

[0114] The various control units 5, 7, phase calculation unit 6, and their methods described in this disclosure can also be implemented by a dedicated computer, which is provided by a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the various control units 5, 7, phase calculation unit 6, and their methods described in this disclosure can also be implemented by a dedicated computer provided by a processor composed of one or more dedicated hardware logic circuits. Alternatively, the various control units 5, 7, phase calculation unit 6, and their methods described in this disclosure can also be implemented by one or more dedicated computers composed of a processor programmed to perform one or more functions, a memory, and a processor composed of one or more hardware logic circuits. Furthermore, the computer program can also be stored as instructions to be executed by the computer on a computer-readable non-volatile tangible recording medium. The aforementioned memory is a non-volatile physical storage medium. By executing the computer program, the control method corresponding to the computer program is executed.

Claims

1. A target detection device for detecting targets, characterized in that, The object detection device includes: a light source that generates light; an emission unit that emits a beam of light generated by the light source in a manner that scans the measurement range; and a detection unit that uses a signal obtained by photoelectric conversion of the reflected light from the object to measure the distance of the object. The high reflectivity determination unit determines whether the signal obtained by photoelectric conversion of reflected light exceeds the dynamic range of the detection unit; the intensity adjustment unit can adjust the intensity of the beam formed by light generated by the same light source. The remeasurement control unit controls the emission unit to emit a low-intensity beam with reduced intensity by the intensity adjustment unit to perform remeasurement when the high reflectivity 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.

2. The object detection device according to claim 1, characterized in that, In the remeasurement, the remeasurement control unit calculates the intensity of the low-intensity beam based on the reflected light received from the specified orientation in the previous measurement, in such a way that the signal obtained by photoelectric conversion of the reflected light reflected from the specified orientation is within the dynamic range of the detection unit.

3. The object detection device according to claim 1 or 2, characterized in that, A frame is defined as one scan of the measurement range by the emission unit from the starting position to the ending position of the measurement. In the remeasurement, the remeasurement control unit controls the emission unit to emit a low-intensity beam to the specified position in the scan within the same frame.

4. The object detection device according to claim 1 or 2, characterized in that, If the high reflectivity determination unit determines that the signal obtained by photoelectric conversion of the reflected light received from the predetermined orientation during the remeasurement exceeds the dynamic range of the detection unit, the remeasurement control unit controls the remeasurement to remeasure by having the emission unit emit a low-intensity beam toward the predetermined orientation in the same frame scan.

5. The object detection device according to claim 4, characterized in that, In the remeasurement, the remeasurement control unit calculates the intensity of the low-intensity beam based on the reflected light received in the remeasurement, in a manner that the signal obtained by photoelectric conversion of the reflected light reflected at the specified orientation is within the dynamic range of the detection unit.

6. The object detection device according to claim 1 or 2, characterized in that, In the remeasurement, the remeasurement control unit controls the emission unit to emit a low-intensity beam to the specified orientation before the emission unit emits a beam to the next orientation in the same frame scan.

7. The object detection device according to claim 1 or 2, characterized in that, A frame is defined as one scan of the measurement range from the starting position to the ending position of the measurement by the emission unit. A scan line is defined as the emission unit scanning in the same straight or curved direction within a frame. In the remeasurement, if the calculation time required by the remeasurement control unit to calculate the intensity of the low-intensity beam in such a way that the signal obtained by photoelectric conversion of the reflected light reflected at the specified position 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 next position at the specified position in the same frame and for the detection unit to measure the distance of the target, after the measurement of the next position or subsequent positions is performed, the remeasurement control unit controls the remeasurement to be performed by emitting a low-intensity beam at any time within the scan line at the specified position.

8. The object detection device according to claim 1 or 2, characterized in that, A frame is defined as one scan of the measurement range by the emission unit from the starting position to the ending position. In the remeasurement, if the calculation time required by the remeasurement control unit to calculate the intensity of the low-intensity beam in such a way that the signal obtained by photoelectric conversion of the reflected light reflected at the specified position 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 next position at the specified position in the same frame and for the detection unit to measure the distance of the target, after the measurement of the next position or subsequent positions is performed, the remeasurement control unit controls the remeasurement to be performed by emitting a low-intensity beam to the specified position at arbitrary timings within the same frame.

9. The object detection device according to claim 1 or 2, characterized in that, The light source generates light in a frequency-modulated continuous wave manner.

10. The object detection device according to claim 1 or 2, characterized in that, The emission section is composed of an optical phased array, which has multiple optical waveguides for distributing and guiding the light generated by the light source, and a phase adjustment section for controlling the phase of the light emitted from the optical antennas at the front ends of the multiple optical waveguides. The optical phased array forms a beam by the light waves emitted from the multiple optical antennas and scans it. In the remeasurement, a low-intensity beam is emitted toward the predetermined direction by the phase control of the optical phased array.

11. The object detection device according to claim 10, characterized in that, During the remeasurement, the intensity adjustment unit can expand the area of ​​the beam perpendicular to the direction of travel to an arbitrary size by controlling the phase of the optical phased array, thereby blurring the light and reducing the intensity of the beam.

12. The object detection device according to claim 10, characterized in that, During the remeasurement, the intensity adjustment unit can, through phase control of the optical phased array, expand the area of ​​the beam perpendicular to the direction of travel in any direction perpendicular to the direction of travel of the beam to blur the light and reduce the intensity of the beam.

13. The object detection device according to claim 10, characterized in that, During the remeasurement, the intensity adjustment unit can adjust the area of ​​the beam perpendicular to the direction of travel by means of nonlinear or randomized phase control including phase shift in the optical phased array, thereby reducing the intensity of the beam.

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