Measuring device, control method for measuring device, control program for measuring device, and computer-readable recording medium having computer program recorded thereon

Abstract

This measuring device comprises: a light emitter that emits light; a light receiver that receives reflected light, which is light that has been emitted by the light emitter and reflected back from a measurement target object; and a controller. The controller: causes the light emitter to sequentially emit light toward a plurality of mutually different locations on the measurement target object at predetermined timings; causes the light receiver to receive the reflected light from each of the plurality of locations; acquires the acceleration of the measurement target object on the basis of a plurality of light reception timings at the light receiver corresponding to each of the plurality of locations (S140); and corrects relative positional relationships in the measurement results for the plurality of locations on the basis of the plurality of light reception timings and the acceleration (S150).

Description

Measuring device, measuring device control method, measuring device control program, and computer-readable recording medium having computer program recorded thereon

[0001] The present disclosure relates to a measurement device, a control method for a measurement device, a control program for a measurement device, and a computer-readable recording medium on which a computer program is recorded.

[0002] With the advancement of AD (Autonomous Driving) and ADAS (Advanced Driver-Assistance Systems), research and development of LiDAR (Light Detection and Ranging) is underway as one of the measurement devices used to grasp the surrounding environment and estimate the vehicle's position while driving. LiDAR is equipped with a reflective sensor. The reflective sensor projects (irradiates) laser light onto a measurement target and receives the reflected light that is reflected back from the measurement target. LiDAR outputs information about the measurement target by measuring the distance to the measurement target based on the time difference between the time when the reflective sensor projects the laser light and the time when it receives the reflected light.

[0003] Conventionally, measurement devices that measure multiple locations on a moving object over time while the moving object is moving relative to the moving object have been known. In these measurement devices, a light projector sequentially emits light toward multiple different locations on the moving object at predetermined timings, and a light receiver receives the light reflected from each of the multiple locations. The shape of the moving object is measured based on multiple light reception timings corresponding to the multiple locations on the light receiver. In such measurement devices, the relative distance between the moving object and the measurement device changes during the time difference between the light projection timing at one location on the moving object and the light projection timing at another location on the moving object. For this reason, conventional measurement devices employ a technique for correcting the relative positional relationship in measurement results of multiple locations on the moving object based on the moving speed of the moving object to offset errors due to the relative distance (see, for example, Patent Document 1).

[0004] International Publication No. 2016 / 115260

[0005] Conventional measuring devices can measure the shape of a moving object with high accuracy when the speed of the moving object is constant. However, when the speed of the moving object is not constant, the shape of the moving object cannot be measured with high accuracy, so there is room for improvement.

[0006] The present inventors have also studied a technology for estimating a predicted arrival time relative to a measurement target, for example, when a measurement device installed on a moving object that moves relative to the measurement target arrives at the measurement target. For example, a measurement device installed on a vehicle can estimate the predicted arrival time using the traveling speed provided by the vehicle. However, traveling speed is generally calculated based on the number of rotations of the wheels and the diameter of the wheels. Therefore, if a deviation occurs in the correlation between the number of rotations of the wheels, the diameter, and the traveling distance due to, for example, variations in the wheel diameter caused by tire wear or tire slippage, the predicted arrival time may not be accurately estimated based on the traveling speed.

[0007] An object of the present disclosure is to provide a light distribution control device, a light distribution control program, a vehicle headlamp, and a vehicle lighting system that can solve the above-mentioned problems.

[0008] A measurement device according to one aspect of the present disclosure includes: a light projector that emits light; a light receiver that receives reflected light that is the light emitted by the light projector reflected off a measurement object and returns; and a controller, wherein the controller: causes the light projector to emit light toward a plurality of different locations on the measurement object at predetermined timings in sequence, causes the light receiver to receive the reflected light from each of the plurality of locations; obtains acceleration of the measurement object based on a plurality of light-receiving timings corresponding to each of the plurality of locations on the light receiver; and corrects the relative positional relationship in the measurement results of the plurality of locations based on the plurality of light-receiving timings and the acceleration.

[0009] A measurement method according to one aspect of the present disclosure is a control method for a measurement device including a light projector that emits light and a light receiver that receives reflected light that is emitted by the light projector and reflected back from an object to be measured, the method comprising: causing the light projector to emit light sequentially toward a plurality of different locations on the object to be measured at predetermined timings; causing the light receiver to receive the reflected light from each of the plurality of locations; obtaining the acceleration of the object to be measured based on a plurality of light receiving timings corresponding to each of the plurality of locations on the light receiver; and correcting the relative positional relationship in the measurement results of the plurality of locations based on the plurality of light receiving timings and the acceleration.

[0010] A control program for a measuring device according to one aspect of the present disclosure includes a computer included in the measuring device, the computer comprising a light projector that emits light and a light receiver that receives reflected light that is returned from the object to be measured, the control program causing the light projector to emit light sequentially at predetermined timings toward a plurality of different locations on the object to be measured, and the light receiver to receive the reflected light from each of the plurality of locations; obtaining the acceleration of the object to be measured based on a plurality of light receiving timings corresponding to each of the plurality of locations on the light receiver; and correcting the relative positional relationship in the measurement results of the plurality of locations based on the plurality of light receiving timings and the acceleration.

[0011] A computer-readable recording medium having recorded thereon a computer program according to one embodiment of the present disclosure is a computer-readable recording medium having recorded thereon a computer program for controlling a measuring device having a light projector that emits light and a light receiver that receives reflected light that is emitted by the light projector and reflected back from an object to be measured, wherein the computer program causes the light projector to emit light sequentially toward a plurality of different locations on the object to be measured at predetermined timings, and causes the light receiver to receive the reflected light from each of the plurality of locations; acquires the acceleration of the object to be measured based on a plurality of light-receiving timings corresponding to each of the plurality of locations on the light receiver; and corrects the relative positional relationship in the measurement results of the plurality of locations based on the plurality of light-receiving timings and the acceleration.

[0012] A measurement device according to another aspect of the present disclosure is a measurement device comprising: a light projector that emits light; a light receiver that receives reflected light that is the light emitted by the light projector reflected off a measurement object and returns; and a controller, wherein the controller acquires the distance to the measurement object and the speed of the measurement object based on the timing at which the reflected light is received by the light receiver, and estimates the estimated arrival time for the measurement device to arrive at the measurement object relative to the measurement object based on the distance to the measurement object and the speed of the measurement object.

[0013] A control method for a measuring device according to another aspect of the present disclosure is a control method for a measuring device comprising: a light projector that emits light; a light receiver that receives reflected light that is the light emitted by the light projector reflected off a measurement object and returns; and a controller, wherein the control method obtains the distance to the measurement object and the speed of the measurement object based on the timing at which the reflected light is received by the light receiver, and estimates an estimated arrival time for the measuring device to arrive at the measurement object relative to the measurement object based on the distance to the measurement object and the speed of the measurement object.

[0014] A control program for a measuring device according to another aspect of the present disclosure causes a computer included in the measuring device, which includes a light projector that emits light, a light receiver that receives reflected light that is returned from the object to be measured after the light emitted by the light projector is reflected by the object to be measured, and a controller, to acquire the distance to the object to be measured and the speed of the object to be measured based on the timing at which the reflected light is received by the light receiver, and to estimate the estimated time at which the measuring device will arrive at the object to be measured relative to the object to be measured based on the distance to the object to be measured and the speed of the object to be measured.

[0015] A computer-readable recording medium having recorded thereon a computer program according to another aspect of the present disclosure is a computer-readable recording medium having recorded thereon a computer program for controlling a measuring device comprising: a light projector that emits light; a light receiver that receives reflected light that is returned from a measurement object after the light projected by the light projector; and a controller, wherein the computer program causes the measuring device to acquire the distance to the measurement object and the speed of the measurement object based on the timing at which the reflected light is received by the light receiver; and causes the measuring device to estimate the estimated arrival time for the measuring device to reach the measurement object relative to the measurement object based on the distance to the measurement object and the speed of the measurement object.

[0016] According to the present disclosure, when the speed of the object to be measured changes, it is possible to suppress a decrease in the measurement accuracy of the relative positional relationship between multiple points on the object to be measured.

[0017] According to the present disclosure, it is possible to estimate the estimated time of arrival of a measurement device relative to an object to be measured, without needing to obtain speed information of the object to be measured from outside.

[0018] The technology disclosed in this specification can be realized in various forms, such as a measuring device, a measuring method, a control program for the measuring device, and a computer-readable recording medium on which a computer program is recorded.

[0019] 1. Block diagram showing the configuration of the measuring device 1 in the first embodiment. 2. Flowchart showing the measurement process. 3. Explanatory diagram showing the results of shape measurement without correction. 4. Explanatory diagram showing the results of shape measurement when corrected with velocity. 5. Explanatory diagram showing the results of shape measurement when corrected with acceleration. 6. Block diagram showing the configuration of the measuring device 100 in the second embodiment. 7. Explanatory diagram showing the relative positional relationship between the measurement object and the measuring device. 8. Flowchart showing the estimation process.

[0020] A. First Embodiment: A-1. Configuration of Measuring Device 1: FIG. 1 is a block diagram showing the configuration of the measuring device 1 in the first embodiment. The measuring device 1 is a device that measures the distance to an object 90. The measuring device 1 functions as a LiDAR. The measuring device 1 measures the distance to the object 90 using the FMCW (Frequency Modulated Continuous Wave) method. That is, the measuring device 1 irradiates the object 90 with frequency-modulated measurement light (irradiation light L1), causes reflected light L2 from the object 90 to interfere with measurement light (reference light L4), and measures the distance to the object 90 based on the frequency (beat frequency) of a beat signal Sb, which is the detection result of the interference light L5. Note that the measuring device 1 can measure not only the distance to the object 90 but also the relative velocity with respect to the object 90.

[0021] The measurement device 1 includes a generating device 10, an optical device 20, a detecting device 30, and a signal processing device 40. The optical device 20 is an example of a light projector and a light receiver.

[0022] The generating device 10 is a device that generates frequency-modulated light (frequency-modulated light L3). The generating device 10 outputs the frequency-modulated light L3 to the optical device 20. A portion of the frequency-modulated light L3 (measurement light) output by the generating device 10 becomes irradiation light L1 that is irradiated onto an object 90, and another portion becomes reference light L4 that is made to interfere with reflected light L2. The generating device 10 has a signal generator 11, a current source 12, a laser light source 13, and a temperature controller 14.

[0023] The signal generator 11 generates a voltage signal for controlling the current source 12. The signal generator 11 is, for example, a waveform generator, and generates, for example, a triangular wave voltage signal and outputs it to the current source 12. The current source 12 generates a current signal for controlling the laser light source 13. The current source 12 generates a current signal corresponding to the voltage signal of the signal generator 11. For example, the current source 12 generates a triangular wave current signal corresponding to the triangular wave voltage signal and outputs it to the laser light source 13.

[0024] The laser light source 13 emits frequency-modulated light (frequency-modulated light L3). For example, the laser light source 13 is configured using a distributed feedback (DFB) laser element. The laser light source 13 generates laser light having a frequency corresponding to the current signal of the current source 12. The laser light generated is frequency-modulated in the range of 193.4024 to 193.4266 THz (λ=1549.903 to 1550.097 nm), for example. For example, the laser light source 13 generates laser light (frequency-modulated light L3) whose frequency gradually increases or decreases according to a triangular wave current signal. The laser light source 13 outputs the laser light to the optical device 20.

[0025] The temperature regulator 14 regulates the temperature of the laser light source 13 (particularly the laser element) to a predetermined temperature. The temperature regulator 14 has, for example, a temperature sensor 14A and a thermoelectric element (e.g., a Peltier element), and measures the temperature of the laser light source 13 with the temperature sensor 14A and adjusts the laser light source 13 to a predetermined temperature by feedback-controlling the thermoelectric element based on the measurement result of the temperature sensor 14A.

[0026] The optical device 20 is a device that irradiates the object 90 with frequency-modulated light (irradiation light L1) and causes reflected light L2 from the object 90 to interfere with reference light L4 (measurement light). The optical device 20 uses a portion of the measurement light (frequency-modulated light L3) input from the generation device 10 as irradiation light L1 to irradiate the object 90, and a portion of the measurement light input from the generation device 10 as reference light L4, and causes the reflected light L2 from the object 90 to interfere with the reference light L4 to generate interference light L5 (interference wave). The optical device 20 outputs the interference light L5 (interference wave) caused by interference between the reflected light L2 and the reference light L4 to the detection device 30.

[0027] The optical device 20 includes a branching device 21, a circulator 22, an optical system 23, an optical waveguide 24, and a coupler 25. The branching device 21 branches the frequency-modulated light L3 from the generation device 10. The branching device 21 is configured, for example, by an optical coupler. One of the branched light beams (frequency-modulated light L3) is output to the circulator 22 and becomes the illumination light L1 that is irradiated onto the object 90. The other branched light beam (frequency-modulated light L3) is output to the optical waveguide 24 and becomes the reference light L4 that interferes with the reflected light L2. The circulator 22 guides the light from the branching device 21 (illumination light L1) to the optical system 23 and guides the light from the optical system 23 (reflected light L2) to the coupler 25.

[0028] The optical system 23 irradiates light (irradiation light L1) toward the object 90 and collects and outputs reflected light L2. The optical system 23 is composed of optical elements such as lenses, mirrors, and prisms. The optical system 23 includes, for example, a light-projecting optical system that irradiates the irradiation light L1 toward the object, and a light-receiving optical system that collects the reflected light L2. The optical system 23 may also have a function of scanning the irradiation light L1. The optical system 23 outputs the collected reflected light L2 to the circulator 22. The reflected light L2 is input to the coupler 25 via the circulator 22.

[0029] The optical waveguide 24 forms an optical path of a predetermined length from the splitter 21 to the coupler 25. The optical waveguide 24 guides the reference light from the splitter 21 to the coupler 25 over a predetermined optical path length. The optical waveguide 24 is formed, for example, of an optical fiber. The coupler 25 combines the reflected light L2 from the circulator 22 with the reference light L4 from the optical waveguide 24. The coupler 25 is formed, for example, of an optical coupler. The coupler 25 functions as an interferometer that causes interference between the reflected light L2 and the reference light L4, and generates interference light L5 (interference wave) by causing interference between the reflected light L2 and the reference light L4. The coupler 25 outputs the interference light L5 to the detection device 30.

[0030] The detection device 30 detects interference light L5 between the reflected light L2 and the reference light L4 and outputs a beat signal Sb. The detection device 30 has a photoelectric converter 31 and an amplifier 32. The photoelectric converter 31 outputs an electrical signal (current signal) corresponding to the intensity of the detected optical signal (here, interference light L5). The photoelectric converter 31 is, for example, a photodiode. The interference light L5 detected by the photoelectric converter 31 is a wave whose amplitude changes periodically due to interference between the reflected light L2 and the reference light L4, which have different frequencies.

[0031] The amplifier 32 converts the current signal of the photoelectric converter 31 into a voltage signal and outputs it. The amplifier 32 is configured, for example, by a transimpedance amplifier. The beat signal Sb output from the amplifier 32 is a signal that indicates the difference in frequency between the reflected light L2 and the reference light L4. The beat frequency of the beat signal Sb corresponds to the frequency of the beat component of the interference light L5. The beat frequency of the beat signal Sb also corresponds to the difference in frequency between the reflected light L2 and the reference light L4.

[0032] The signal processing device 40 is a device that calculates the distance to the object 90 based on the beat signal Sb. The signal processing device 40 has an A / D converter, an arithmetic unit, a storage device, etc. (not shown). The arithmetic unit is composed of an arithmetic processing device such as a CPU, a GPU, or an MPU. The storage device is composed of a main storage device and an auxiliary storage device, and is a device that stores programs and data. The arithmetic unit executes the programs stored in the storage device, thereby performing various processes for measuring the distance to the object 90. In FIG. 1, the various processes performed by the signal processing device 40 are shown as functional blocks. The signal processing device 40 is an example of a controller.

[0033] The signal processing device 40 has a signal acquiring unit 41, an analyzing unit 42, and an output unit 43. The signal acquiring unit 41 acquires the beat signal Sb of the detection device 30 as a digital signal. The signal acquiring unit 41 is configured, for example, by an A / D converter (such as an A / D conversion board). The analyzing unit 42 calculates the distance to the object 90 based on the beat signal Sb. The output unit 43 outputs the analysis result of the analyzing unit 42 to the outside. For example, the output unit 43 outputs distance data indicating the distance to the object 90 and speed data indicating the relative speed of the object 90 to a vehicle ECU, which is an external device.

[0034] A-2. Measurement Process: The measurement device 1 executes the measurement process. The measurement process involves sequentially irradiating a plurality of different locations on the measurement target (object 90) with irradiation light L1 at predetermined timings, receiving reflected light L2 from each of the locations, and measuring the shape of the measurement target based on multiple light-receiving timings corresponding to each of the locations. The optical device 20, for example, has multiple light-emitting elements (laser elements) arranged in a predetermined direction. The optical device 20 causes each of the multiple light-emitting elements to emit light in a time-division manner, sequentially irradiating the plurality of locations on the object 90 with irradiation light L1, and receiving reflected light L2 from each of the locations (hereinafter, this series of operations is referred to as the "light-emitting and receiving operation"). In the following description, the multiple light-emitting elements are arranged vertically, and emit light in order from the lowest light-emitting element to the highest light-emitting element.

[0035] 2 is a flowchart showing the measurement process. When the signal processing device 40 receives an instruction to start measurement from, for example, an external device, it executes the measurement process shown in FIG. 2. The signal processing device 40 determines whether the measurement timing has arrived (S110). The measurement timing is the timing that triggers the start of the measurement process of the measurement device 1 in one frame unit (the process of performing the above-mentioned light emission and reception operation once to obtain the measurement result (point cloud data)). If the signal processing device 40 determines that the measurement timing has not arrived (S110: NO), it waits as is.

[0036] When the signal processing device 40 determines that the measurement timing has arrived (S110: YES), it causes the optical device 20 to perform a light projection and reception operation (S120). This allows the signal processing device 40 to acquire one frame of point cloud data. The point cloud data is data on multiple measurement points P corresponding to multiple different locations on the object 90. The multiple measurement points P are arranged at equal intervals in the vertical direction (Z coordinate in FIGS. 3 to 5 described below). The positional relationship of the multiple measurement points P in the horizontal direction (Y coordinate in FIGS. 3 to 5 described below) corresponds to the time difference between the TOFs (Time of Flight) of the multiple measurement points P. TOF is the time difference between the light projection timing at which the measurement device 1 emits the irradiated light L1 and the light reception timing at which the reflected light L2 is received. A measurement point P with a relatively short TOF is closer to the measurement device 1 than a measurement point P with a relatively long TOF.

[0037] Next, the signal processing device 40 acquires velocity data indicating the relative velocity (hereinafter simply referred to as "velocity v") of the object 90 (S130). As described above, the measuring device 1 of the first embodiment employs the FMCW method, and therefore can acquire the relative velocity of the object 90 (each measurement point P) based on one frame of point cloud data.

[0038] Next, the signal processing device 40 acquires acceleration data indicating the relative acceleration (hereinafter simply referred to as "acceleration α") of the object 90 (S140). For example, the signal processing device 40 acquires acceleration data for each measurement point P based on changes in velocity v between multiple different frames. Specifically, for each measurement point P, the signal processing device 40 acquires acceleration data based on changes in velocity v in the frame at the immediately previous measurement timing. ０ and the velocity v in the frame at this measurement timing １ The acceleration α is calculated from the difference between

[0039] The signal processing device 40 corrects the relative positional relationship in the measurement results of the plurality of points based on the plurality of light receiving timings (point cloud data) corresponding to the plurality of points and the acceleration α (S150). Specifically, the signal processing device 40 calculates the measurement position Y of each measurement point P based on the following equation 1: １ the position Y of the measurement point P after correction １ｈCorrect to Y １ｈ = Y １ - [(1 / 2) × (v １ -v ０ ) × Δt ２ ]-(v １ × Δt) Formula 1 Δt: Time difference between the previous measurement timing and the current measurement timing

[0040] Thereafter, the signal processing device 40 returns to S110. Note that the signal processing device 40 may return to S110 and execute the next light projection and reception operation before completing the processes of S130 to S150. In other words, the processes of S130 to S150 for one frame and the light projection and reception operation for the next frame may be executed simultaneously in parallel.

[0041] A-3. Effects of the First Embodiment: FIG. 3 is an explanatory diagram showing the results of shape measurement without correction. FIG. 4 is an explanatory diagram showing the results of shape measurement when corrected with velocity v, and FIG. 5 is an explanatory diagram showing the results of shape measurement when corrected with acceleration α. ​​In each diagram, a vehicle is illustrated as the object 90. Assume that the object 90 is not traveling at a constant speed, but is decelerating by braking. The first measurement point Pb is a measurement point corresponding to the lowest point at the front end of the object 90. The final measurement points Pt1 to Pt3 are measurement points corresponding to the highest points at the front end of the object 90. Hereinafter, the horizontal distance between the lowest and highest points of the object 90 will be referred to as the vehicle position deviation E.

[0042] As described above, the measuring device 1 is configured to sequentially irradiate the irradiation light L1 toward a plurality of different locations on the measurement target (object 90) at predetermined timings. Therefore, in one light projection and reception operation, there is a time difference (hereinafter referred to as the "light projection time difference") between the light projection timing corresponding to the first measurement point Pb and the last measurement point Pt1. During this light projection time difference, the object 90 approaches the measuring device 1 at a speed v, and the relative distance between the object 90 and the measuring device 1 changes.

[0043] FIG. 3 shows point cloud data acquired by the light projecting and receiving operation without correction. If no correction process is performed on the point cloud data acquired by the light projecting and receiving operation of S120, the measurement result of the shape of the object 90 will deviate from the correct shape of the object 90 depending on the relative distance. For example, as shown in FIG. 3, in the horizontal direction, the position deviation ΔE1 of the position Dt1 of the last measurement point Pt1 relative to the position Db of the first measurement point Pb significantly deviates from the vehicle position deviation E on the object 90. The position Dt1 of the last measurement point Pt1 is located forward of the position Db of the first measurement point Pb by the position deviation ΔE1. ​​The error between the position Dt1 of the last measurement point Pt1 and the correct position Dt of the highest point of the object 90 is the sum of the vehicle position deviation E and the position deviation ΔE1.

[0044] FIG. 4 shows point cloud data corrected by the velocity v of the object 90. Even when correction processing is performed on the point cloud data acquired by the light projection and reception operation of S120 based on the velocity v (velocity v is constant), the measurement result of the shape of the object 90 deviates from the correct shape of the object 90. This is because, as described above, the velocity v of the object 90 is not constant but changes (decelerates) during the light projection time difference. For example, as shown in FIG. 4 , in the horizontal direction, the position deviation ΔE2 of the position Dt2 of the last measurement point Pt2 relative to the position Db of the first measurement point Pb deviates from the vehicle position deviation E on the object 90. The position Dt2 of the last measurement point Pt2 is located behind the position Db of the first measurement point Pb by the position deviation ΔE2. The error between the position Dt2 of the last measurement point Pt2 and the correct position Dt of the highest point of the object 90 is the position deviation ΔE2 minus the vehicle position deviation E.

[0045] 5 shows point cloud data corrected by the acceleration α of the object 90. When the point cloud data acquired by the light emitting and receiving operation of S120 is corrected based on the acceleration α, the measurement results of the shape of the object 90 approach the correct shape of the object 90. For example, as shown in FIG. 5, in the horizontal direction, the position deviation of the position Dt3 of the last measurement point Pt3 from the position Db of the first measurement point Pb coincides with the vehicle position deviation E on the object 90. The position Dt3 of the last measurement point Pt3 is located behind the position Db of the first measurement point Pb by the amount of the vehicle position deviation E.

[0046] B. Modifications: The technology disclosed in this specification is not limited to the first embodiment described above, and can be modified in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0047] The configuration of the measuring device 1 in the first embodiment is merely an example, and various modifications are possible. For example, the measuring device 1 is a flash type, but is not limited to this, and may be a scanning type equipped with a scanner. Furthermore, the measuring device 1 may be fixed at a predetermined position or may be disposed on a mobile body.

[0048] In the first embodiment, the measurement device 1 employs the FMCW method. However, a measurement device other than the FMCW method may also be used. Such a measurement device can calculate the velocity of the measurement object based on the positional deviation of each measurement point between multiple frames and the light projection period. Then, the velocities between frames at different timings are acquired, and the acceleration of the measurement object can be obtained based on the difference between these velocities. For example, for a certain measurement point, a first velocity is calculated based on the positional deviation between its position in a first frame and its position in a subsequent second frame and the light projection period. Next, a second velocity is calculated based on the positional deviation between its position in the second frame and its position in a subsequent third frame and the light projection period. The acceleration of the measurement object is obtained from the difference between the first velocity and the second velocity.

[0049] In the first embodiment, measurement of the shape of the measurement object in the vertical direction (up and down direction) has been exemplified, but the present invention is not limited to this and may also be applied to measurement of the shape in the horizontal direction.

[0050] C. Second Embodiment: C-1. Configuration of Measuring Device 100: FIG. 6 is a block diagram showing the configuration of the measuring device 100 in this second embodiment. The measuring device 100 is a device that measures the distance to an object 190. The measuring device 100 has a LiDAR function. The measuring device 100 measures the distance to the object 190 using the FMCW method. That is, the measuring device 100 irradiates the object 190 with frequency-modulated measuring light (irradiation light L101), causes reflected light L102 from the object 190 to interfere with the measuring light (reference light L104), and measures the distance to the object 190 based on the frequency (beat frequency) of the beat signal Sb, which is the detection result of the interference light L105. Note that the measuring device 100 can measure not only the distance to the object 190 but also the relative velocity with respect to the object 190.

[0051] The measurement device 100 includes a generating device 110, an optical device 120, a detecting device 130, and a signal processing device 140. The optical device 120 is an example of a light projector and a light receiver.

[0052] The generating device 110 is a device that generates frequency-modulated light (frequency-modulated light L103). The generating device 110 outputs the frequency-modulated light L103 to the optical device 120. A part of the frequency-modulated light L103 (measurement light) output by the generating device 110 becomes irradiation light L101 that is irradiated onto the object 190, and another part becomes reference light L104 that is made to interfere with reflected light L102. The generating device 110 has a signal generator 111, a current source 112, a laser light source 113, and a temperature regulator 114.

[0053] The signal generator 111 generates a voltage signal for controlling the current source 112. The signal generator 111 is, for example, a waveform generator, and generates, for example, a triangular wave voltage signal and outputs it to the current source 112. The current source 112 generates a current signal for controlling the laser light source 113. The current source 112 generates a current signal corresponding to the voltage signal of the signal generator 111. For example, the current source 112 generates a triangular wave current signal corresponding to the triangular wave voltage signal and outputs it to the laser light source 113.

[0054] The laser light source 113 emits frequency-modulated light (frequency-modulated light L103). For example, the laser light source 113 is configured using a distributed feedback (DFB) laser element. The laser light source 113 generates laser light having a frequency corresponding to the current signal of the current source 112. The laser light generated is frequency-modulated in the range of 193.4024 to 193.4266 THz (λ=1549.903 to 1550.097 nm), for example. For example, the laser light source 113 generates laser light (frequency-modulated light L103) whose frequency gradually increases or decreases according to a triangular wave current signal. The laser light source 113 outputs the laser light to the optical device 120.

[0055] The temperature regulator 114 regulates the temperature of the laser light source 113 (particularly the laser element) to a predetermined temperature. The temperature regulator 114 has, for example, a temperature sensor 114A and a thermoelectric element (for example, a Peltier element), and measures the temperature of the laser light source 113 with the temperature sensor 114A and adjusts the laser light source 113 to a predetermined temperature by feedback-controlling the thermoelectric element based on the measurement result of the temperature sensor 114A.

[0056] The optical device 120 is a device that irradiates the object 190 with frequency-modulated light (irradiation light L101) and causes reflected light L102 from the object 190 to interfere with reference light L104 (measurement light). The optical device 120 uses a portion of the measurement light (frequency-modulated light L103) input from the generation device 110 as irradiation light L101 to irradiate the object 190, and a portion of the measurement light input from the generation device 110 as reference light L104, and causes the reflected light L102 from the object 190 to interfere with the reference light L104 to generate interference light L105 (interference wave). The optical device 120 outputs the interference light L105 (interference wave) caused by interference between the reflected light L102 and the reference light L104 to the detection device 130.

[0057] The optical device 120 includes a branching device 121, a circulator 122, an optical system 123, an optical waveguide 124, and a coupler 125. The branching device 121 branches the frequency-modulated light L103 from the generation device 110. The branching device 121 is configured, for example, by an optical coupler. One of the branched light beams (frequency-modulated light L103) is output to the circulator 122 and becomes the irradiation light L101 that is irradiated onto the object 190. The other branched light beam (frequency-modulated light L103) is output to the optical waveguide 124 and becomes the reference light L104 that interferes with the reflected light L102. The circulator 122 guides the light from the branching device 121 (irradiation light L101) to the optical system 123 and guides the light from the optical system 123 (reflected light L102) to the coupler 125.

[0058] The optical system 123 irradiates light (irradiation light L101) toward the object 190 and collects and outputs reflected light L102. The optical system 123 is composed of optical elements such as lenses, mirrors, and prisms. The optical system 123 includes, for example, a light-projecting optical system that irradiates the irradiation light L101 toward the object, and a light-receiving optical system that collects the reflected light L102. The optical system 123 may also have a function of scanning the irradiation light L101. The optical system 123 outputs the collected reflected light L102 to the circulator 122. The reflected light L102 is input to the coupler 125 via the circulator 122.

[0059] The optical waveguide 124 forms an optical path of a predetermined length from the splitter 121 to the coupler 125. The optical waveguide 124 guides the reference light from the splitter 121 to the coupler 125 over a predetermined optical path length. The optical waveguide 124 is formed, for example, by an optical fiber. The coupler 125 combines the reflected light L102 from the circulator 122 with the reference light L104 from the optical waveguide 124. The coupler 125 is formed, for example, by an optical coupler. The coupler 125 functions as an interferometer that causes interference between the reflected light L102 and the reference light L104, and generates interference light L105 (interference wave) by causing interference between the reflected light L102 and the reference light L104. The coupler 125 outputs the interference light L105 to the detection device 130.

[0060] The detection device 130 detects the interference light L105 between the reflected light L102 and the reference light L104 and outputs a beat signal Sb. The detection device 130 has a photoelectric converter 131 and an amplifier 132. The photoelectric converter 131 outputs an electrical signal (current signal) corresponding to the intensity of the detected optical signal (here, the interference light L105). The photoelectric converter 131 is, for example, a photodiode. The interference light L105 detected by the photoelectric converter 131 is a wave whose amplitude changes periodically due to interference between the reflected light L102 and the reference light L104, which have different frequencies.

[0061] The amplifier 132 converts the current signal of the photoelectric converter 131 into a voltage signal and outputs it. The amplifier 132 is configured, for example, by a transimpedance amplifier. The beat signal Sb output from the amplifier 132 is a signal that indicates the difference in frequency between the reflected light L102 and the reference light L104. The beat frequency of the beat signal Sb corresponds to the frequency of the beat component of the interference light L105. The beat frequency of the beat signal Sb also corresponds to the difference in frequency between the reflected light L102 and the reference light L104.

[0062] The signal processing device 140 is a device that calculates the distance to the object 190 based on the beat signal Sb. The signal processing device 140 has an A / D converter, an arithmetic unit, a storage device, etc. (not shown). The arithmetic unit is composed of an arithmetic processing device such as a CPU, a GPU, or an MPU. The storage device is composed of a main storage device and an auxiliary storage device, and is a device that stores programs and data. The arithmetic unit executes the programs stored in the storage device, thereby performing various processes for measuring the distance to the object 190. FIG. 6 shows the various processes performed by the signal processing device 140 as functional blocks. The signal processing device 140 is an example of a controller.

[0063] The signal processing device 140 includes a signal acquiring unit 141, an analyzing unit 142, and an output unit 143. The signal acquiring unit 141 acquires the beat signal Sb of the detection device 130 as a digital signal. The signal acquiring unit 141 is configured, for example, by an A / D converter (such as an A / D conversion board). The analyzing unit 142 calculates the distance to the object 190 based on the beat signal Sb. The output unit 143 outputs the analysis result of the analyzing unit 142 to the outside. For example, the output unit 143 outputs distance data indicating the distance to the object 190 and speed data indicating the relative speed of the object 190 to a vehicle ECU, which is an external device.

[0064] C-2. Estimation Process: Fig. 7 is an explanatory diagram showing the relative positional relationship between the measurement object and the measurement device, and Fig. 8 is a flowchart showing the estimation process. The estimation process is a process of detecting unevenness on the road surface R and estimating the estimated arrival time relative to the detected unevenness by the measurement device 100. Fig. 7 shows a convex portion R1 as an example of the unevenness on the road surface R. It is assumed that the object 190 is traveling toward the convex portion R1 at a speed v with an acceleration α. ​​The unevenness on the road surface R (convex portion R1) is an example of the measurement object.

[0065] When the signal processing device 140 receives an instruction to start measurement from, for example, an external device, it executes the estimation process shown in Fig. 8. The signal processing device 140 determines whether the measurement timing has arrived (S210). The measurement timing is the timing that triggers the start of the measurement process of the measurement device 100 in units of one frame (the process of performing a light emission and reception operation, described below, once to obtain a measurement result (point cloud data)). If the signal processing device 140 determines that the measurement timing has not arrived (S210: NO), it waits.

[0066] When the signal processing device 140 determines that the measurement timing has arrived (S210: YES), it causes the optical device 120 to perform a light projection and reception operation (S220). The light projection and reception operation is an operation in which irradiation light L101 is directed toward multiple different locations on the measurement object (such as the convex portion R1) and reflected light L102 from each of the multiple locations is received. In this way, the signal processing device 140 acquires one frame's worth of point cloud data. The point cloud data is data on multiple measurement points corresponding to each of the multiple different locations on the measurement object.

[0067] Next, the signal processing device 140 determines whether or not there is a measurement target based on the timing of receiving reflected light L102 from multiple locations (point cloud data) (S230). The measurement target here refers to an object, background, etc. measured by the measurement device 100 that satisfies the execution conditions for estimating the estimated arrival time. In the second embodiment, for example, this refers to unevenness in the road surface R that has a height difference equal to or greater than a predetermined reference value. If the signal processing device 140 determines that there is no measurement target (S230: NO), it returns to S210 and waits until the next measurement timing.

[0068] When the signal processing device 140 determines that a measurement object is present (S230: YES), it acquires the distance D from the measuring device 100 to the measurement object (protrusion R1) based on the point cloud data (S240).

[0069] Next, the signal processing device 140 acquires velocity data indicating the relative velocity of the measuring device 100 with respect to the measurement target (hereinafter simply referred to as "velocity v") (S250). As described above, the measuring device 100 of the second embodiment employs the FMCW method, and therefore can acquire velocity v based on one frame of point cloud data.

[0070] Next, the signal processing device 140 acquires acceleration data indicating the relative acceleration of the measuring device 100 with respect to the measurement target (hereinafter simply referred to as "acceleration α") (S260). The signal processing device 140 acquires acceleration data based on, for example, changes in velocity v between multiple different frames for each measurement point of the point cloud data. Specifically, the signal processing device 140 acquires acceleration data based on changes in velocity v between multiple different frames for each measurement point at the frame at the previous measurement timing. ０ and the velocity v in the frame at this measurement timing １ The acceleration α is calculated from the difference between

[0071] The signal processing device 140 can correct the relative positional relationship in the measurement results of the multiple locations based on multiple light receiving timings (point cloud data) corresponding to the multiple locations and the acceleration α. ​​Specifically, the signal processing device 140 calculates the measurement position Y of each measurement point based on the following equation 2: １ the position Y of the measurement point after correction １ｈ Correct to Y １ｈ = Y １ - [(1 / 2) × (v １ -v ０ ) × Δt ２ ]-(v １ × Δt) Formula 2 Δt: Time difference between the previous measurement timing and the current measurement timing

[0072] Next, the signal processing device 140 estimates the estimated arrival time (S270). Here, the estimated arrival time is a predicted time from the measurement timing at which the measurement target (protrusion R1) is detected until the measuring device 100 (object 190) reaches the measurement target. The signal processing device 140 estimates the estimated arrival time based on the distance D to the measurement target (protrusion R1), the speed v of the measurement target, and the acceleration α of the measurement target. By considering not only the speed v of the measurement target but also the acceleration α of the measurement target, the signal processing device 140 can grasp the speed fluctuations until the measuring device 100 (object 190) reaches the measurement target, thereby enabling accurate estimation of the estimated arrival time.

[0073] Next, the signal processing device 140 outputs the estimated estimated time to an external device (such as the vehicle body) (S280). Based on the estimated estimated time, the vehicle body may, for example, adjust the strength of the vehicle suspension to reduce elevation fluctuations of the vehicle caused by unevenness in the road surface R, or may slow down or stop the vehicle.

[0074] Thereafter, the signal processing device 140 returns to S210. Note that the signal processing device 140 may return to S210 and execute the next light projection and reception operation before completing the processes of S230 to S280. In other words, the processes of S230 to S280 for one frame and the light projection and reception operation for the next frame may be executed simultaneously in parallel.

[0075] C-3. Advantages of the Second Embodiment: As described above, in the measuring device 100 according to the second embodiment, the signal processing device 140 estimates the estimated time of arrival based on the distance D to the measurement target (protrusion R1) and the speed v of the measurement target (S240, S250, S270 in FIG. 8). As a result, according to the second embodiment, it is possible to estimate the estimated time of arrival of the measuring device 100 relative to the measurement target without needing to obtain speed information (traveling speed, etc.) of the measurement target from an external source.

[0076] In the second embodiment, the signal processing device 140 estimates the estimated time of arrival based on the acceleration α of the object to be measured (S260 in FIG. 8 ). This makes it possible to prevent a decrease in the accuracy of estimating the estimated time of arrival due to fluctuations in the speed of the measuring device 100 when the measuring device 100 (object 190) accelerates or decelerates.

[0077] D. Modifications: The technology disclosed in this specification is not limited to the second embodiment described above, and can be modified in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0078] The configuration of the measuring device 100 in the second embodiment is merely an example, and various modifications are possible. For example, the measuring device 100 is a flash type, but is not limited to this, and may be a scanning type equipped with a scanner. Also, the measuring device 100 may be fixed at a predetermined position, and the measurement target may move relative to the measuring device 100. Also, both the measuring device 100 and the measurement target may move relative to each other. The measurement target is not limited to the unevenness of the road surface R, but may also be, for example, an object on the road surface R (such as an obstacle or sign) or an object outside the road surface R (such as an obstacle or sign).

[0079] In the second embodiment, the measurement device 100 employs the FMCW method. However, a measurement device other than the FMCW method may also be used. Such a measurement device can calculate the velocity of the measurement object based on the positional deviation of each measurement point between multiple frames and the light projection period. Then, the velocities between frames at different timings are acquired, and the acceleration of the measurement object can be obtained based on the difference between these velocities. For example, for a certain measurement point, a first velocity is calculated from the positional deviation between its position in a first frame and its position in a subsequent second frame and the light projection period. Next, a second velocity is calculated from the positional deviation between its position in the second frame and its position in a subsequent third frame and the light projection period. The acceleration of the measurement object is obtained from the difference between the first velocity and the second velocity.

[0080] In the estimation process of the second embodiment, the signal processing device 140 may always execute the processes from S240 onwards without executing the determination of S230. Also, in the estimation process, the signal processing device 140 may estimate the estimated time of arrival based on the distance D to the measurement target and the speed v of the measurement target without executing the process of S250.

[0081] This application is based on Japanese patent applications filed on February 19, 2024 (Patent Application No. 2024-022565) and February 19, 2024 (Patent Application No. 2024-022566), the contents of which are incorporated herein by reference.

Claims

1. A measuring device comprising: a light projector that emits light; a light receiver that receives reflected light that is the light emitted by the light projector reflected off an object to be measured and returns; and a controller, wherein the controller: causes the light projector to emit light sequentially at predetermined timings toward a plurality of different locations on the object to be measured, and causes the light receiver to receive the light reflected from each of the plurality of locations; obtains the acceleration of the object to be measured based on a plurality of light-receiving timings on the light receiver corresponding to each of the plurality of locations; and corrects the relative positional relationship in the measurement results of the plurality of locations based on the plurality of light-receiving timings and the acceleration.

2. A measuring device according to claim 1, wherein the measuring device is of an FMCW type, and the controller acquires the acceleration of the object to be measured based on the velocity difference at each location between multiple frames.

3. A control method for a measuring device that includes a light projector that emits light and a light receiver that receives reflected light that is emitted by the light projector and reflected off an object to be measured, the control method comprising: causing the light projector to emit light sequentially at predetermined timings toward a plurality of different locations on the object to be measured; causing the light receiver to receive the reflected light from each of the plurality of locations; obtaining the acceleration of the object to be measured based on a plurality of light-receiving timings corresponding to each of the plurality of locations on the light receiver; and correcting the relative positional relationship in the measurement results of the plurality of locations based on the plurality of light-receiving timings and the acceleration.

4. A control program for a measuring device that includes a light projector that emits light and a light receiver that receives the reflected light that is emitted by the light projector and reflected back from the object to be measured, the program causing the light projector to emit light sequentially at predetermined timings toward a plurality of different locations on the object to be measured, causing the light receiver to receive the reflected light from each of the plurality of locations, obtaining the acceleration of the object to be measured based on a plurality of light-receiving timings corresponding to each of the plurality of locations on the light receiver, and correcting the relative positional relationship in the measurement results of the plurality of locations based on the plurality of light-receiving timings and the acceleration.

5. A computer-readable recording medium having recorded thereon a computer program for controlling a measuring device equipped with a light projector that emits light and a light receiver that receives the light that is reflected back from the object to be measured, the computer program comprising: causing the light projector to emit light sequentially at predetermined timings toward a plurality of different locations on the object to be measured; causing the light receiver to receive the light reflected from each of the plurality of locations; obtaining the acceleration of the object to be measured based on a plurality of light-receiving timings corresponding to each of the plurality of locations on the light receiver; and correcting the relative positional relationship in the measurement results of the plurality of locations based on the plurality of light-receiving timings and the acceleration.

6. A measuring device comprising: a light projector that emits light; a light receiver that receives reflected light that is the light emitted by the light projector reflected off an object to be measured and returned; and a controller, wherein the controller obtains the distance to the object to be measured and the speed of the object to be measured based on the timing of reception of the reflected light by the light receiver, and estimates the estimated time for the measuring device to arrive at the object to be measured relative to the object to be measured based on the distance to the object to be measured and the speed of the object to be measured.

7. A measuring device according to claim 6, wherein the controller further acquires the acceleration of the object to be measured based on the timing of reception of the reflected light by the light receiver, and estimates the expected arrival time based on the distance to the object to be measured, the speed of the object to be measured, and the acceleration of the object to be measured.

8. A measuring device according to claim 7, wherein the measuring device is of an FMCW type, and the controller acquires the acceleration of the object to be measured based on a difference in velocity of the object to be measured between a plurality of frames.

9. A control method for a measuring device comprising: a light projector that emits light; a light receiver that receives reflected light that is the light emitted by the light projector reflected off an object to be measured and returned; and a controller, the control method for a measuring device comprising: acquiring the distance to the object to be measured and the speed of the object to be measured based on the timing at which the reflected light is received by the light receiver; and estimating the estimated time for the measuring device to arrive at the object to be measured relative to the object to be measured based on the distance to the object to be measured and the speed of the object to be measured.

10. A control program for a measuring device that includes a light projector that emits light, a light receiver that receives reflected light that is emitted by the light projector and reflected back from an object to be measured, and a controller, which causes a computer included in the measuring device to acquire the distance to the object to be measured and the speed of the object to be measured based on the timing of reception of the reflected light by the light receiver, and to estimate the estimated time of arrival of the measuring device relative to the object to be measured based on the distance to the object to be measured and the speed of the object to be measured.

11. A computer-readable recording medium having recorded thereon a computer program for controlling a measuring device comprising: a light projector that emits light; a light receiver that receives the reflected light that is returned from the light projector after being reflected by an object to be measured; and a controller, the computer program causing the measuring device to acquire the distance to the object to be measured and the speed of the object to be measured based on the timing of reception of the reflected light by the light receiver; and causing the measuring device to estimate the estimated time of arrival at the object to be measured relative to the object to be measured based on the distance to the object to be measured and the speed of the object to be measured.

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