Measurement system

Abstract

A measurement system comprises: a light source that emits irradiation light for irradiating a target region; a scanner that changes the irradiation angle of the irradiation light; a photodetector that detects reflected light from the target region and outputs a detection signal; a processing circuit that drives the scanner so as to perform Lissajous scanning of the target region, irradiates the target region with the irradiation light, and generates measurement data on the basis of the detection signal; and a memory that stores the measurement data. The processing circuit stores, in the memory, measurement data from which data within a disturbance period determined on the basis of disturbance during measurement has been removed, or measurement data in which data within the disturbance period and data outside the disturbance period are distinguished from each other.

Description

Measurement System

[0001] The present disclosure relates to measurement systems.

[0002] Conventionally, measurement systems that scan a target area with an irradiated light to acquire measurement data including distance information are known. Such measurement systems can be used in mobile objects that move autonomously while estimating their own position, such as autonomous mobile robots (AMRs or automated guided vehicles (AGVs)), self-driving cars, and autonomous drones. The self-position estimation is performed by comparing a map generated based on the measurement data with a map of the surrounding environment. Creating a map requires acquiring measurement data from which disturbances such as moving objects have been removed. Patent Document 1 discloses an example of a measurement system that acquires measurement data from which measurement points on moving objects have been removed.

[0003] A typical example of a method for scanning a target region with irradiated light is raster scanning, which sequentially performs horizontal scanning in the vertical direction. Another example is Lissajous scanning, which simultaneously performs periodic scanning in two mutually orthogonal directions. Patent Document 2 discloses an example of a measurement system that acquires measurement data using Lissajous scanning.

[0004] International Publication No. 2023 / 062862 Japanese Patent Application Laid-Open No. 2011-053137

[0005] The present disclosure provides a measurement system that can efficiently acquire measurement data from which disturbances have been removed, based on the measurement results obtained by measuring a target area using a scan that is different from raster scanning.

[0006] A measurement system according to one aspect of the present disclosure includes a light source that emits illumination light to illuminate a target area, a scanner that changes the illumination angle of the illumination light, a photodetector that detects reflected light from the target area and outputs a detection signal, a processing circuit that drives the scanner to perform a Lissajous scan of the target area to illuminate the target area with the illumination light and generates measurement data based on the detection signal, and a memory that stores the measurement data, wherein the processing circuit stores in the memory the measurement data from which data within a disturbance period determined based on a disturbance during measurement has been removed, or the measurement data from which data within the disturbance period and data outside the disturbance period have been distinguished.

[0007] A comprehensive or specific aspect of the present disclosure may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable recording disk, or as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. The computer-readable recording medium may include, for example, a non-volatile recording medium such as a CD-ROM (Compact Disc-Read Only Memory). An apparatus may consist of one or more devices. When an apparatus consists of two or more devices, the two or more devices may be located in a single device or may be located separately in two or more separate devices. In this specification and claims, the term "apparatus" may refer not only to a single device but also to a system consisting of multiple devices. The multiple devices included in a "system" may include devices installed in remote locations away from other devices and connected via a communication network.

[0008] According to the technology of the present disclosure, a measurement system can be realized that can efficiently acquire measurement data from which disturbances have been removed, based on the measurement results obtained by measuring a target area using a scan other than a raster scan.

[0009] FIG. 1A is a diagram schematically illustrating an example of raster scanning a target region. FIG. 1B is a flowchart schematically illustrating an example of measurement operations when raster scanning a target region. FIG. 2A is a diagram illustrating a specific example of one cycle of Lissajous scanning. FIG. 2B is a diagram for explaining how a target region is scanned at different trajectories in one cycle of Lissajous scanning. FIG. 3A is a diagram schematically illustrating an example of Lissajous scanning a target region. FIG. 3B is a flowchart schematically illustrating an example of measurement operations when Lissajous scanning a target region. FIG. 4A is a block diagram schematically illustrating a configuration of a measurement system according to a first exemplary embodiment of the present disclosure. FIG. 4B is a diagram illustrating an example of measurement data stored in a memory in the first embodiment. FIG. 4C is a diagram illustrating another example of measurement data stored in a memory in the first embodiment. FIG. 5 is a flowchart schematically illustrating an example of measurement operations performed by a processing circuit in the first embodiment. FIG. 6 is a flowchart schematically illustrating an example of measurement operations performed by a processing circuit in a first modification of the first embodiment. FIG. 7A is a flowchart schematically illustrating an example of a measurement operation performed by a processing circuit in Modification 2 of Embodiment 1. FIG. 7B is a flowchart schematically illustrating an example of a processing operation performed by a processing circuit in step S1150 shown in FIG. 7A. FIG. 8A is a flowchart schematically illustrating an example of a measurement operation performed by a processing circuit in Modification 3 of Embodiment 1. FIG. 8B is a flowchart schematically illustrating an example of a processing operation performed by a processing circuit in step S1160 shown in FIG. 8A. FIG. 9A is a flowchart schematically illustrating an example of a measurement operation performed by a processing circuit in Modification 4 of Embodiment 1. FIG. 9B is a flowchart schematically illustrating an example of a processing operation performed by a processing circuit in step S1450 shown in FIG. 9A. FIG. 10A is a block diagram schematically illustrating a configuration of a measurement system according to an exemplary embodiment 2 of the present disclosure. FIG. 10B is a diagram illustrating an example of measurement data stored in a memory in Embodiment 2. FIG. 11A is a diagram schematically illustrating time changes in the frequencies of the reference light and the reflected light when the object is stationary. FIG. 11B is a diagram schematically showing the time changes in the frequencies of the reference light and the reflected light when an object approaches the measurement device.FIG. 12 is a flowchart schematically illustrating an example of a measurement operation performed by a processing circuit in embodiment 2. FIG. 13 is a flowchart schematically illustrating an example of a measurement operation performed by a processing circuit in modification 1 of embodiment 2. FIG. 14A is a flowchart schematically illustrating an example of a measurement operation performed by a processing circuit in modification 2 of embodiment 2. FIG. 14B is a flowchart schematically illustrating an example of a processing operation performed by a processing circuit in step S2150 shown in FIG. 14A. FIG. 15A is a flowchart schematically illustrating an example of a measurement operation performed by a processing circuit in modification 3 of embodiment 2. FIG. 15B is a flowchart schematically illustrating an example of a processing operation performed by a processing circuit in step S2160 shown in FIG. 15A. FIG. 16A is a block diagram schematically illustrating the configuration of a measurement system according to exemplary embodiment 3 of the present disclosure. FIG. 16B is a diagram illustrating example measurement data stored in a memory in embodiment 3. FIG. 17 is a flowchart schematically illustrating an example of a measurement operation performed by a processing circuit in embodiment 3. FIG. 18 is a flowchart schematically illustrating an example of a measurement operation performed by a processing circuit in Modification 1 of Embodiment 3. FIG. 19A is a flowchart schematically illustrating an example of a measurement operation performed by a processing circuit in Modification 2 of Embodiment 3. FIG. 19B is a flowchart schematically illustrating an example of a processing operation performed by a processing circuit in step S3150 shown in FIG. 19A. FIG. 20A is a flowchart schematically illustrating an example of a measurement operation performed by a processing circuit in Modification 3 of Embodiment 3. FIG. 20B is a flowchart schematically illustrating an example of a processing operation performed by a processing circuit in step S3160 shown in FIG. 20A. FIG. 21A is a flowchart schematically illustrating an example of a measurement operation performed by a processing circuit in Embodiment 4. FIG. 21B is a flowchart schematically illustrating an example of a processing operation performed by a processing circuit in step S4020 shown in FIG. 21A. FIG. 22A is a block diagram schematically illustrating another configuration of a measurement system according to exemplary Embodiment 1 of the present disclosure, and a data processing device that performs post-processing of measurement data. FIG. 22B is a diagram showing an example of post-processed measurement data stored in memory.

[0010] In the present disclosure, all or part of a circuit, unit, device, component, or part, or all or part of a functional block in a block diagram, may be implemented by one or more electronic circuits, including, for example, a semiconductor device, a semiconductor integrated circuit (IC), or an LSI (large scale integration). The LSI or IC may be integrated on a single chip or may be configured by combining multiple chips. For example, functional blocks other than memory elements may be integrated on a single chip. While the terms LSI and IC are used here, the term may be changed depending on the degree of integration, and may be referred to as a system LSI, a VLSI (very large scale integration), or an ULSI (ultra large scale integration). A Field Programmable Gate Array (FPGA), which is programmed after the LSI is manufactured, or a reconfigurable logic device, which can reconfigure the connection relationships within the LSI or set up circuit sections within the LSI, can also be used for the same purpose.

[0011] Furthermore, all or part of the functions or operations of a circuit, unit, device, component, or section can be implemented by software processing. In this case, the software is recorded on one or more non-transitory recording media such as ROMs, optical disks, hard disk drives, etc., and when the software is executed by a processor, the functions specified in the software are executed by the processor and peripheral devices. A system or device may include one or more non-transitory recording media on which the software is recorded, a processor, and required hardware devices, such as interfaces.

[0012] In this disclosure, "light" refers to electromagnetic waves including not only visible light (wavelengths of about 400 nm to about 700 nm), but also ultraviolet light (wavelengths of about 10 nm to about 400 nm) and infrared light (wavelengths of about 700 nm to about 1 mm).

[0013] Exemplary embodiments of the present disclosure will be described below. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components that are not recited in the independent claims that represent the highest concepts will be described as optional components. Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Furthermore, in each figure, substantially identical components are assigned the same reference numerals, and duplicated descriptions may be omitted or simplified.

[0014] First, the findings that form the basis of this disclosure will be described.

[0015] When obtaining measurement data from which disturbances have been removed based on the measurement results of raster scanning a target area, the following problems may arise. FIG. 1A is a diagram schematically illustrating an example of raster scanning a target area. The target area is a room containing a television, a chair, and a door. A person is crossing the target area from left to right. Diagrams (a1) to (a5) of FIG. 1A are schematic diagrams illustrating how the horizontal scanning of the target area is performed sequentially from bottom to top in one raster scan cycle. Diagrams (a1) to (a5) of FIG. 1A show time elapsed from left to right. Diagrams (b1) to (b5) of FIG. 1A show measurement results from which non-zero velocity locations have been removed as disturbances. Diagrams (b1) to (b5) of FIG. 1A correspond to Diagrams (a1) to (a5) of FIG. 1A, respectively. Diagram (c) of FIG. 1A shows the overall measurement results obtained by one raster scan cycle.

[0016] In raster scanning, the target area is partially scanned repeatedly in one cycle, as shown in (a1) to (a5) of Fig. 1A. As shown in (b2) and (b3) of Fig. 1A, missing areas are created in each measurement result due to a person crossing the target area. As a result, missing areas remain in the overall measurement result, as shown in (c) of Fig. 1A.

[0017] 1B is a flowchart showing an example of a measurement operation when raster scanning a target area. The flowchart shown in FIG. 1B includes steps S101 to S107. The operations of steps S101 to S107 are as follows. In one cycle of raster scanning, the operations of steps S101 to S106 are repeatedly executed. After one cycle of raster scanning is completed, the operation of step S107 is executed.

[0018] <Step S101> It is determined whether one cycle of raster scanning has been completed. If the determination in step S101 is yes, the operation of step S107 is executed. If the determination in step S101 is no, the operation of step S102 is executed.

[0019] <Step S102> The irradiation position is moved.

[0020] <Step S103> Measurement is carried out.

[0021] <Step S104> It is determined whether or not there is a disturbance. If the determination is yes, the operation of step S105 is executed. If the determination is no, the operation of step S106 is executed.

[0022] <Step S105> The fact that a disturbance has occurred at the current irradiation position is stored in memory.

[0023] <Step S106> The measurement data is stored in memory, after which the operation of step S101 is executed.

[0024] <Step S107> It is determined whether or not there is erroneous measurement data due to disturbance in the measurement data. If the determination is yes, the operations of steps S101 to S106 are executed again to correct the erroneous measurement data. If the determination is no, the measurement operation ends.

[0025] In this way, when measurement data from which disturbances have been removed is obtained based on the measurement results obtained by raster scanning the target area, it is necessary to perform measurements again to correct erroneous measurement data.

[0026] The present inventors have identified the above-mentioned problem and have devised a measurement system according to an embodiment of the present disclosure that can solve this problem. The measurement system according to this embodiment can efficiently acquire measurement data from which disturbances have been removed, based on measurement results obtained by measuring a target area using a scan other than raster scanning. An example of a scan other than raster scanning is a Lissajous scan.

[0027] Fig. 2A is a diagram showing an example of one cycle of Lissajous scanning. Diagrams (a1) to (a10) in Fig. 2A show how the target region is scanned in chronological order, dividing one cycle into 10 parts. The black dots in Fig. 2A represent measurement points at a certain irradiation angle, and the solid line in Fig. 2A represents the scanning trajectory.

[0028] In the example shown in FIG. 2A, the range of irradiation angles corresponding to the target region is from -25° to 25° in the horizontal direction and from -25° to 25° in the vertical direction. The horizontal and vertical vibration frequencies of the Lissajous scan are 10.1 Hz and 9.9 Hz, respectively. There are 3,000 measurement points per cycle. Therefore, there are 300 measurement points per second, and the measurement time per measurement point is 0.00333 seconds.

[0029] As shown in (a1) to (a10) of Fig. 2A, in one cycle of Lissajous scanning, the target region is repeatedly scanned with different trajectories. Two measurement points on different trajectories may be closer to each other than two consecutive measurement points on the same trajectory. Two measurement points located close to each other are close to each other in space but not in time.

[0030] It is possible that measurement data at a certain measurement point on one of the different trajectories is affected by a disturbance, but measurement data at a nearby measurement point on at least one of the remaining trajectories is not affected by the disturbance. In this case, even if measurement data at a certain measurement point is erased, measurement data at nearby measurement points is not erased. Therefore, it is unlikely that missing areas will occur in the overall measurement results.

[0031] In the example shown in Figure 2A, there are gaps in the region of interest that are not scanned in each trajectory, which can be reduced by increasing the horizontal and vertical oscillation frequencies of the Lissajous scan.

[0032] FIG. 2B is a diagram showing another example of one cycle of a Lissajous scan. Diagrams (a1) to (a10) of FIG. 2B are similar to diagrams (a1) to (a10) of FIG. 2A. In the example shown in FIG. 2B, the horizontal and vertical vibration frequencies of the Lissajous scan are higher and the number of measurement points is greater than in the example shown in FIG. 2A. The horizontal and vertical vibration frequencies of the Lissajous scan are 101 Hz and 99.9 Hz, respectively. One cycle is 10 seconds. There are 200,000 measurement points per cycle. Therefore, there are 20,000 measurement points per second, and the measurement time per measurement point is 0.00005 seconds.

[0033] In the example shown in Figure 2B, similar to the example shown in Figure 2A, the target area is repeatedly scanned with different trajectories in one Lissajous scan. However, due to the large number of measurement points, the scanning trajectories are not clearly visible. In the example shown in Figure 2B, unlike the example shown in Figure 2A, there are no large blank areas in the target area in each trajectory. Therefore, missing areas are less likely to occur in the overall measurement results.

[0034] 3A is a diagram schematically illustrating an example of a Lissajous scan of a target region. Diagrams (a1) to (a5) of FIG. 3A are diagrams schematically illustrating five iterations of scanning the target region along different trajectories in one Lissajous scan cycle. Diagrams (b1) to (b5) and (c) of FIG. 3A are similar to diagrams (b1) to (b5) and (c) of FIG. 1A.

[0035] In a Lissajous scan, as shown in (a1) to (a5) of FIG. 3A, the operation of scanning the entire target area is repeated in one cycle. As shown in (b1) to (b5) of FIG. 3A, each measurement result has a missing area due to a person crossing the target area. However, the location where the missing area occurs in each measurement result is different. In other words, even if a missing area occurs in the measurement result of one trajectory at the same position, the missing area does not occur in the measurement result of another trajectory. Therefore, as shown in (c) of FIG. 3A, no missing area remains in the overall measurement result.

[0036] 3B is a flowchart showing an example of a measurement operation when performing Lissajous scanning on a target region. The flowchart shown in FIG. 3B includes steps S101 to S108. The operations of steps S101 to S107 are as described with reference to FIG. 1B. However, if the determination in step S107 is yes, the operation of step S108 is executed.

[0037] <Step S108> Erroneous measurement data is erased, and then the measurement operation ends.

[0038] In this way, when measurement data from which disturbances have been removed is obtained based on the measurement results of a Lissajous scan of the target region, there is no need to perform remeasurement to correct erroneous measurement data, and therefore measurement data from which disturbances have been removed can be obtained efficiently.

[0039] Measurement systems according to first to fourth embodiments of the present disclosure will be described in detail below.

[0040] First Embodiment [Measurement System] First, a configuration example of a measurement system according to a first embodiment of the present disclosure will be described with reference to Fig. 4A. This measurement system measures distance information using a time-of-flight (ToF) LiDAR (Light Detecting And Ranging) technique.

[0041] Fig. 4A is a block diagram schematically illustrating the configuration of a measurement system according to the first exemplary embodiment of the present disclosure. Fig. 4A also illustrates a target area 10 to be measured. The target area 10 includes a plurality of measurement points 12. Two or more different measurement points 12 may be expressed using ordinal numbers, such as a "first measurement point" and a "second measurement point." In Fig. 4A, thick lines with arrows represent the flow of light, and thin lines with arrows represent the flow of signals.

[0042] 4A includes a measurement device 60A, a first processing circuit 52a, a control circuit 54, and a memory 56. In three-dimensional measurement of a target area 10, the measurement device 60A performs a Lissajous scan of the target area 10 with illumination light 20La to acquire measurement data including distance information at a plurality of measurement points 12 within the target area 10. An example of one cycle of a Lissajous scan is as described with reference to FIG. 2B .

[0043] More specifically, the distance information at the measurement point 12 is distance information about an object present at the measurement point 12. The distance information is information about distance. The information about distance may be information about the distance itself or information from which the distance can be derived.

[0044] The measurement device 60A includes a light source 20, a scanner 30, a photodetector 40, and a second processing circuit 52b. The light source 20 emits illumination light 20La for illuminating the target area 10. Each measurement point 12 within the target area 10 is illuminated with the illumination light 20La. The illumination light 20La may be, for example, a laser beam. The scanner 30 changes the illumination angle of the illumination light 20La. The scanner 30 may include, for example, a first optical deflector that changes the illumination angle θ in the horizontal X direction and a second optical deflector that changes the illumination angle φ in the vertical Y direction. The first and second optical deflectors can be driven independently, enabling a Lissajous scan to be performed by two-axis scanning. The first and second optical deflectors may be, for example, galvanometer mirrors. The photodetector 40 detects reflected light 20Lb from the target area 10 and outputs a detection signal. The second processing circuit 52b generates measurement data including distance information at the measurement point 12 based on the detection signal.

[0045] The first processing circuit 52a sets a scan plan. The scan plan includes, for example, determining the angular range in the X and Y directions in the target region 10, the number of measurement points 12, and parameters of the Lissajous function. The first processing circuit 52a stores the measurement data generated by the second processing circuit 52b in the memory 56. If a disturbance occurs during measurement, the first processing circuit 52a stores the measurement data in the memory 56 from which data during the disturbance period has been removed. Alternatively, the first processing circuit 52a may store the measurement data in the memory 56 from which data during the disturbance period has been distinguished from data outside the disturbance period. The disturbance period is determined based on the disturbance during measurement. An example of a disturbance that reduces the reliability of measurement data is a moving object. In this specification, the term "measurement data" may refer to multiple measurement data obtained by scanning or to measurement data at a specific measurement point 12.

[0046] The control circuit 54 controls the operation of the measurement device 60A. Specifically, the control circuit 54 causes the light source 20 to emit the irradiation light 20La. The control circuit 54 also drives the scanner 30 to perform a Lissajous scan of the target area 10, causing the irradiation light 20La to irradiate multiple measurement points 12 within the target area 10. The control circuit 54 also causes the photodetector 40 to detect reflected light 20Lb from the target area 10 and output a detection signal. If the photodetector 40 constantly detects light and outputs a detection signal, the control circuit 54 does not need to control the photodetector 40. The control circuit 54 also causes the second processing circuit 52b to generate measurement data based on the detection signal.

[0047] The memory 56 stores the measurement results, the criteria used to determine whether a disturbance exists, and the disturbance period. The memory 56 may be, for example, a RAM or a flash memory. The memory 56 may be part of a storage element provided in the first processing circuit 52a for the purpose of storing and executing programs and circuit logic. The first processing circuit 52a, the control circuit 54, and the memory 56 may be integrated on a single circuit board or provided on separate circuit boards.

[0048] In this specification, the first processing circuit 52a, the control circuit 54, and the second processing circuit 52b are collectively referred to as the "processing circuit 50." Examples of measurement operations performed by the processing circuit 50 will be described later.

[0049] [Example of Measurement Data] Figure 4B is a diagram showing an example of measurement data stored in memory 56 in embodiment 1. As shown in Figure 4B, the measurement data includes the time, coordinates, and irradiation direction for each measurement point 12. The time represents the measurement time at the measurement point 12. The coordinates represent the Cartesian coordinate position of the measurement point 12 in the coordinate space to be measured. The irradiation direction represents the irradiation angles θ and φ of the irradiation light 20La at the measurement point 12, with the scanner 30 as the origin. Since distance information is measured for each measurement point 12 while changing the irradiation angle of the irradiation light 20La by biaxial scanning, the time, coordinates, and irradiation direction are different for each measurement point 12. The multiple measurement data are treated as point cloud data.

[0050] FIG. 4C is a diagram showing another example of measurement data stored in memory 56 in embodiment 1. Compared to the measurement data shown in FIG. 4B, the measurement data shown in FIG. 4C includes irradiation direction and distance, i.e., polar coordinates, instead of irradiation direction. The distance in polar coordinates is used to calculate the absolute value of the difference in distance between two nearby measurement points 12, i.e., the distance deviation. When the measurement data only has Cartesian coordinates, as shown in FIG. 4B, it is converted to polar coordinates for comparison. The measurement data shown in FIG. 4C further includes a code indicating the presence or absence of a disturbance. For example, a measurement point 12 where a disturbance has occurred is flagged with "1," and a measurement point 12 where no disturbance has occurred is flagged with "0."

[0051] [Example of Measurement Operation] In the first embodiment, measurement data during a disturbance period is not stored in the memory 56, and measurement data during a period other than the disturbance period is stored in the memory 56. The disturbance period is determined based on the measurement times at two nearby measurement points 12 where a distance difference occurs.

[0052] 5 is a flowchart that schematically illustrates an example of a measurement operation performed by the processing circuitry 50 in embodiment 1. The processing circuitry 50 performs steps S1010 to S1140 shown in FIG. 5. In the following description, the operations performed by the first processing circuitry 52a, the second processing circuitry 52b, and the control circuitry 54 may be interpreted as operations performed by the processing circuitry 50.

[0053] <Step S1010> The first processing circuit 52a determines whether a signal indicating the end of scanning has been input. If the determination is yes, the measurement operation ends. If the determination is no, the first processing circuit 52a executes the operation of step S1020.

[0054] <Step S1020> The first processing circuitry 52a sets a scan plan for performing a Lissajous scan on the target region 10, and transmits the scan plan to the control circuitry 54.

[0055] <Step S1030> The control circuit 54 determines whether one unit of measurement operation based on the scan plan has been completed. One unit of measurement operation in which the target area 10 is repeatedly scanned corresponds to, for example, one cycle of a Lissajous scan, one frame of a video when the target area 10 is photographed by a camera, or a cycle of periodic storage and transfer of measurement data.

[0056] One period of a Lissajous scan is as follows: In a Lissajous scan, if the ratio of the vibration frequencies in the horizontal and vertical directions is a rational number, one period can be defined as the time it takes for the measurement point 12 to return from the initial measurement point 12 to the same measurement point 12. However, if this ratio is an irrational number, the measurement point 12 does not return to the initial measurement point 12. In this case, the time required to irradiate a predetermined number of measurement points 12 may be defined as one period.

[0057] <Step S1040> The control circuit 54 determines the unmeasured irradiation direction as the irradiation position.

[0058] <Step S1050> The control circuit 54 controls the light source 20, the scanner 30, and the photodetector 40 to cause the measurement device 60A to perform measurement.

[0059] <Step S1060> The first processing circuit 52a determines whether the measurement time at the measurement point 12 is within a disturbance period (to be described later). If the determination is yes, the control circuit 54 executes the operation of step S1030. If the determination is no, the second processing circuit 52b executes the operation of step S1070.

[0060] <Step S1070> The second processing circuit 52b calculates the distance at the measurement point 12 based on the measurement result.

[0061] <Step S1080> The first processing circuit 52a determines whether or not there is a measurement point 12 located near the current measurement point 12 among the past measurement points 12. The absolute value of the difference between the irradiation angle of the current measurement point 12 and the irradiation angle of a previous measurement point 12 located near the current measurement point 12 is smaller than, for example, a predetermined reference angle. The predetermined reference angle can be, for example, the absolute value of the difference between the irradiation angle at the current measurement point 12 and the irradiation angle at the measurement point 12 to be measured next in a Lissajous scan.

[0062] In this specification, the irradiation angle at the past measurement point 12 is also referred to as the "first irradiation angle," and the irradiation angle at the current measurement point 12 is also referred to as the "second irradiation angle."

[0063] <Step S1090> The first processing circuit 52a stores the measurement data exemplified in FIG. 4B in the memory 56.

[0064] <Step S1100> The first processing circuit 52a determines whether the absolute value of the difference between the distance at the current measurement point 12 and the distance at a previous measurement point 12 located nearby, i.e., the distance deviation, is greater than a predetermined reference distance. The distances at these measurement points 12 are distances in polar coordinates. The predetermined reference distance may be, for example, the maximum absolute value of stationary noise when measuring the distance. In this case, it is possible to prevent erroneous determinations due to stationary noise. If the distance deviation is greater than the predetermined reference distance, it can be estimated that a moving object in the target area 10 is illuminated with the illumination light 20La.

[0065] If the determination is yes, the first processing circuit 52a executes the operation of step S1110. If the determination is no, the first processing circuit 52a executes the operation of step S1090.

[0066] <Step S1110> The first processing circuit 52a determines a disturbance period that includes the measurement time at the current measurement point 12. The disturbance period includes a first period from the measurement time at a nearby past measurement point 12 to the measurement time at the current measurement point 12. It is estimated that a disturbance occurred during the first period, which is a past period. The disturbance period further includes a second period that is shorter than the first period and extends from the measurement time at the current measurement point 12. The second period may be, for example, half the first period. It is estimated that a disturbance will occur during the second period, which is a future period. The disturbance period, which includes the first period and the second period, is a period during which the reliability of the measurement data is considered low due to a disturbance.

[0067] In this specification, the measurement time at the past measurement point 12 is also referred to as the "first measurement time," and the measurement time at the current measurement point 12 is also referred to as the "second measurement time."

[0068] <Step S1120> The first processing circuit 52a erases the past measurement data at the measurement points 12 during the disturbance period from the memory 56. Thereafter, the control circuit 54 executes the operation of step S1030.

[0069] <Step S1130> The first processing circuit 52a determines whether to output the point cloud data, more specifically, whether to display the point cloud data on the display, based on the following setting: This setting may be, for example, real-time display, display at regular intervals, or display for every predetermined number of measurement points 12.

[0070] If the determination is yes, the first processing circuit 52a executes the operation of step S1140. If the determination is no, the control circuit 54 executes the operation of step S1030.

[0071] <Step S1140> The first processing circuit 52a outputs the measurement data, and more specifically, displays the measurement data on the display. After that, the control circuit 54 executes the operation of step S1030.

[0072] 5, unreliable measurement data from within the disturbance period is not stored in memory 56, and highly reliable measurement data from outside the disturbance period is stored in memory 56. Because a Lissajous scan is performed on target area 10, even if measurement data from within the disturbance period is not stored in memory 56, as explained with reference to FIG. 3A, no missing area occurs in the overall measurement results, and remeasurement is not necessary. Therefore, measurement data from which disturbance has been removed can be efficiently obtained.

[0073] (Variation 1 of Embodiment 1) In Variation 1 of Embodiment 1, measurement data during a disturbance period is not displayed but is stored in memory 56. If measurement data during a disturbance period were displayed, the visibility of point clouds not affected by the disturbance would decrease. In Variation 1 of Embodiment 1, measurement data during a disturbance period is not displayed, so the decrease in visibility can be prevented, and measurement data is retained to enable post-processing.

[0074] FIG. 6 is a flowchart schematically illustrating an example of a measurement operation performed by the processing circuit 50 in Modification 1 of Embodiment 1. The measurement operation illustrated in FIG. 6 differs from the measurement operation illustrated in FIG. 5 in the following four points. First, the processing circuit 50 performs the operation of step S1070 after step S1050. Second, the processing circuit 50 performs the operation of step S1061 after step S1070, instead of step S1060 illustrated in FIG. 5. Third, the processing circuit 50 performs the operation of step S1121 instead of step S1120 illustrated in FIG. 5. Fourth, the processing circuit 50 performs the operation of step S1141 instead of step S1140 illustrated in FIG. 5.

[0075] <Step S1061> The first processing circuit 52a determines whether the measurement time is within the disturbance period. If the determination is yes, the first processing circuit 52a executes the operation of step S1121. If the determination is no, the first processing circuit 52a executes the operation of step S1080.

[0076] <Step S1121> The first processing circuit 52a stores the measurement data illustrated in Fig. 4C in the memory 56. Not only the measurement data at the current measurement point 12 during the disturbance period, but also the measurement data at past measurement points 12 are assigned a code indicating a disturbance and stored in the memory 56. In this way, the first processing circuit 52a uses the code indicating a disturbance to store in the memory 56 the measurement data in which data during the disturbance period and data outside the disturbance period are distinguished. Thereafter, the control circuit 54 executes the operation of step S1030.

[0077] <Step S1141> The first processing circuit 52a outputs the measurement data outside the disturbance period, more specifically, displays the measurement data outside the disturbance period on the display. The measurement data during the disturbance period is not output, more specifically, the measurement data during the disturbance period is not displayed on the display. Thereafter, the control circuit 54 executes the operation of step S1030.

[0078] The measurement operation shown in Fig. 6 makes it possible to efficiently obtain measurement data from which disturbances have been removed, similar to the measurement operation shown in Fig. 5. Furthermore, post-processing of the measurement data is also possible.

[0079] (Second Modification of First Embodiment) In a second modification of the first embodiment, disturbances are removed by post-processing the measurement data.

[0080] 7A is a flowchart schematically illustrating an example of a measurement operation performed by the processing circuitry 50 in Modification 2 of Embodiment 1. The measurement operation illustrated in FIG. 7A differs from the measurement operation illustrated in FIG. 6 in the following respects. That is, the processing circuitry 50 performs the operation of step S1150 after step S1030.

[0081] <Step S1150> The first processing circuit 52a determines the presence or absence of a disturbance for the measurement data within the disturbance period for each unit of the measurement operation described above, and causes the memory 56 to erase the code indicating the disturbance that was assigned to the measurement data not affected by the disturbance. This is because the disturbance period determined in embodiment 1 may also include a period in which no disturbance actually occurs. In this way, the measurement data that is not actually affected by the disturbance is restored. The operation of step S1150 may be performed offline on the measurement data stored in the memory 56.

[0082] Fig. 7B is a flowchart that schematically illustrates an example of the processing operation performed by the processing circuitry 50 in step S1150 shown in Fig. 7A. The processing circuitry 50 performs the operations of steps S1151 to S1156 shown in Fig. 7B.

[0083] <Step S1151> The first processing circuit 52a extracts measurement data within a disturbance period in one unit of measurement operation.

[0084] <Step S1152> The first processing circuit 52a determines whether or not unprocessed measurement data exists among the extracted measurement data. If the determination is yes, the first processing circuit 52a executes the operation of step S1153. If the determination is no, the first processing circuit 52a executes the operation of step S1010.

[0085] <Step S1153> The first processing circuit 52a selects one of the unprocessed measurement data.

[0086] <Step S1154> The first processing circuit 52a extracts the following measurement data from the measurement data outside the disturbance period in one unit of measurement operation. The irradiation angle at the measurement point 12 of the measurement data extracted in step S1154 is close to the irradiation angle at the measurement point 12 of the measurement data selected in step S1153. That is, the absolute value of the difference between these two irradiation angles is smaller than a predetermined reference angle. The predetermined reference angle can be determined based on, for example, the spatial density of the measurement points 12 during measurement and the variance of the irradiation angle per unit time. Alternatively, the same reference angle as in step S1080 may be used.

[0087] <Step S1155> The first processing circuit 52a compares the measurement data selected in step S1153 with the measurement data extracted in step S1154. More specifically, the first processing circuit 52a determines whether the absolute value of the difference between the distance at measurement point 12 of the measurement data selected in step S1153 and the distance at measurement point 12 of the measurement data extracted in step S1154, i.e., whether the distance deviation, is greater than a predetermined reference distance. The predetermined reference distance is as described in step S1100. If a plurality of measurement data are extracted in step S1154, the distance of the measurement data with the closest irradiation angle may be used. Alternatively, the average or median of the distances of the plurality of extracted measurement data may be used.

[0088] If the determination is yes, the first processing circuit 52a executes the operation of step S1152. Alternatively, the first processing circuit 52a may erase the measurement data selected in step S1153 from the memory 56. If the determination is no, the first processing circuit 52a executes the operation of step S1156. In this case, the distance deviation is equal to or less than a predetermined reference distance.

[0089] <Step S1156> The first processing circuit 52a erases the code indicating the disturbance that was attached to the measurement data selected in step S1153 from the memory 56. In other words, the first processing circuit 52a stores the measurement data selected in step S1153 as normal measurement data in the memory 56. Thereafter, the first processing circuit 52a executes the operation of step S1152.

[0090] The processing operation shown in Fig. 7B can correct an erroneous determination of a disturbance. When the processing operation shown in Fig. 7B is performed offline, it may be performed by a processing circuit included in a separately provided data processing device, instead of the first processing circuit 52a.

[0091] (Third Modification of First Embodiment) In a third modification of the first embodiment, measurement data affected by a disturbance is replaced or interpolated with measurement data not affected by the disturbance.

[0092] 8A is a flowchart schematically illustrating an example of a measurement operation performed by the processing circuitry 50 in Modification 3 of Embodiment 1. The measurement operation illustrated in FIG. 8A differs from the measurement operation illustrated in FIG. 6 in the following respects. That is, the processing circuitry 50 performs the operation of step S1160 after step S1030.

[0093] <Step S1160> The first processing circuit 52a determines the presence or absence of a disturbance for the measurement data within the disturbance period for each unit of the measurement operation described above, and erases the code indicating the disturbance that was assigned to the measurement data not affected by the disturbance in the memory 56. The first processing circuit 52a further replaces or interpolates the measurement data affected by the disturbance with measurement data not affected by the disturbance for the measurement data within the disturbance period. The operation of step S1160 may be performed offline on the measurement data stored in the memory 56.

[0094] 8B is a flowchart that schematically illustrates an example of the processing operation performed by the processing circuit 50 in step S1160 shown in FIG. 8A. The processing operation shown in FIG. 8B differs from the processing operation shown in FIG. 7B in the following two respects. First, after step S1154, the processing circuit 50 performs the operation of step S1165 instead of step S1155 shown in FIG. 7B. Second, if the determination in step S1165 is yes, the processing circuit 50 performs the operations of steps S1167 to S1169.

[0095] <Step S1165> The first processing circuit 52a determines whether the absolute value of the difference between the distance at the measurement point 12 of the measurement data selected in step S1153 and the distance at the measurement point 12 of the measurement data extracted in step S1154, i.e., the distance deviation, is greater than a predetermined reference distance.

[0096] If the determination is yes, the first processing circuit 52a executes the operation of step S1167. If the determination is no, the first processing circuit 52a executes the operation of step S1156.

[0097] <Step S1167> The first processing circuit 52a determines whether or not the number of measurement data extracted in step S1154 is plural, that is, whether or not there are plural measurement points 12 located in the vicinity. If the determination is yes, the first processing circuit 52a executes the operation of step S1169. If the determination is no, the first processing circuit 52a executes the operation of step S1168.

[0098] <Step S1168> The first processing circuit 52a replaces the measurement data selected in step S1153 with the one measurement data extracted in step S1154, and stores the replaced data in the memory 56. Thereafter, the first processing circuit 52a executes the operation of step S1152.

[0099] <Step S1169> The first processing circuit 52a interpolates the measurement data selected in step S1153 using the average or median value of the distances of the multiple measurement data extracted in step S1154. The first processing circuit 52a further generates orthogonal coordinates for the interpolated measurement data based on the irradiation direction and distance, and stores the coordinates in the memory 56. Thereafter, the first processing circuit 52a executes the operation of step S1152.

[0100] 8B , measurement data affected by a disturbance at a certain measurement point 12 during the disturbance period can be replaced or interpolated with measurement data not affected by the disturbance at at least one other measurement point 12 outside the disturbance period. Removing measurement data affected by the disturbance can cause a bias in the spatial density of the measurement data. By replacing or interpolating the measurement data, such a bias can be prevented.

[0101] (Fourth Modification of First Embodiment) In a fourth modification of the first embodiment, measurement data not stored in the memory 56 during a disturbance period is replaced or interpolated with measurement data outside the disturbance period.

[0102] 9A is a flowchart schematically illustrating an example of a measurement operation performed by the processing circuitry 50 in Modification 4 of Embodiment 1. The measurement operation illustrated in FIG. 9A differs from the measurement operation illustrated in FIG. 5 in the following respects. That is, the processing circuitry 50 performs the operation of step S1450 after step S1030.

[0103] <Step S1450> When the first processing circuit 52a determines that the measurement based on the scan plan has ended, it replaces or interpolates the measurement data that has not been stored in the memory 56 during the disturbance period with measurement data at nearby measurement points 12.

[0104] 9B is a flowchart schematically illustrating an example of the processing operation performed by the processing circuitry 50 in step S1450 shown in FIG. 9A. The processing circuitry 50 performs the operations of steps S1451, S1152 to S1154, and S1167 to S1169 shown in FIG. 9B. The operations of steps S1152 to S1154 are as described with reference to FIG. 7B. The operations of steps S1167 to S1169 are as described with reference to FIG. 8B.

[0105] <Step S1451> The first processing circuitry 52a compares the irradiation directions included in the scan plan with the irradiation directions stored in the memory 56, and extracts irradiation directions that are not stored in the memory 56. Thereafter, the first processing circuitry 52a executes the operations of steps S1152 to S1154 and S1167 to S1169.

[0106] 9B , measurement data not stored in memory 56 during the disturbance period can be replaced or interpolated with measurement data from outside the disturbance period. If measurement data is not stored during the disturbance period, a bias in the spatial density of the measurement data can occur. By replacing or interpolating the measurement data, such a bias can be prevented.

[0107] Second Embodiment [Measurement System] Hereinafter, a configuration example of a measurement system according to a second embodiment of the present disclosure will be described with reference to Fig. 10A . This measurement system uses FMCW (Frequency Modulated Continuous Wave) LiDAR technology to measure not only distance information but also velocity information. The presence or absence of disturbance can be determined from the velocity information.

[0108] Fig. 10A is a block diagram schematically illustrating the configuration of a measurement system according to a second exemplary embodiment of the present disclosure. The measurement system 100B illustrated in Fig. 10A differs from the measurement system 100A illustrated in Fig. 4A in the following respects. That is, the measurement system 100B includes a measurement device 60B instead of the measurement device 60A illustrated in Fig. 4A.

[0109] In three-dimensional measurement of the target area 10, the measurement device 60B performs a Lissajous scan of the target area 10 with the illumination light 20La to acquire measurement data including distance information and velocity information at a plurality of measurement points 12 within the target area 10. More specifically, the distance information and velocity information at the measurement points 12 is distance information and velocity information of an object present at the measurement points 12. The velocity information is information related to velocity. The information related to velocity may be information about the velocity itself, or may be information from which the velocity can be derived.

[0110] The measurement device 60B includes a light source 20, an optical interference system 62, a scanner 30, a photodetector 40, and a second processing circuit 52b. The light source 20 emits light including illumination light 20La for illuminating the target area 10. The frequency of this light is periodically modulated. This light may be, for example, laser light. Since this light includes the illumination light 20La, it can be said that the light source 20 emits illumination light 20La for illuminating the target area 10. The optical interference system 62 separates the light emitted from the light source 20 into the illumination light 20La and a reference light. The optical interference system 62 further generates interference light by causing reflected light 20Lb from the target area 10 to interfere with the reference light. The scanner 30 changes the irradiation direction of the illumination light 20La. The photodetector 40 detects the interference light including the reflected light 20Lb and outputs a detection signal. Since the interference light includes the reflected light 20Lb, it can be said that the photodetector 40 detects the reflected light 20Lb and outputs a detection signal. The second processing circuit 52b uses the FMCW method to simultaneously generate distance information and velocity information at the measurement point 12 based on the detection signal. Specifically, as will be described later, the second processing circuit 52b analyzes the frequency spectrum of the interference light from the detection signal and calculates the distance and velocity based on peaks that appear in the frequency spectrum.

[0111] Details of the measuring device 60B are disclosed in, for example, Japanese Patent Application Laid-Open No. 2022-139736, the entire disclosure of which is incorporated herein by reference.

[0112] [Example of Measurement Data] The measurement data stored in the memory 56 in the second embodiment may be the same as the measurement data shown in Figures 4B and 4C. Alternatively, the measurement data stored in the memory 56 in the second embodiment may include velocity.

[0113] Fig. 10B is a diagram showing an example of measurement data stored in memory 56 in embodiment 2. The measurement data shown in Fig. 10B differs from the measurement data shown in Fig. 4C in the following respects. That is, the measurement data includes velocity instead of a code indicating the presence or absence of a disturbance. The velocity at measurement point 12 is velocity in polar coordinates. The velocity in polar coordinates is a component of the object velocity projected in the irradiation direction. A non-zero velocity is stored at measurement point 12 where a disturbance has occurred.

[0114] [Method of Measuring Distance and Speed] Next, a method of measuring distance and speed using the FMCW method will be briefly described with reference to FIGS. 11A and 11B.

[0115] FIG. 11A is a schematic diagram showing the temporal changes in the frequencies of the reference light and reflected light 20Lb when the object is stationary. The solid line represents the reference light, and the dashed line represents the reflected light. The frequency of the reference light shown in FIG. 11A repeatedly changes over time in a triangular waveform. That is, the frequency of the reference light alternates between up-chirp and down-chirp. The frequency increase in the up-chirp and the frequency decrease in the down-chirp are equal to each other. The frequency of the reflected light 20Lb shifts along the time axis compared to the frequency of the reference light. The amount of time shift of the reflected light 20Lb is equal to the time it takes for the irradiated light to be emitted from the measurement device 60B, reflected by the object, and returned as reflected light 20Lb. As a result, the interference light resulting from interference between the reference light and reflected light 20Lb has a frequency corresponding to the difference between the frequency of the reflected light 20Lb and the frequency of the reference light. The double-headed arrow in FIG. 11A represents the difference between the two frequencies. The photodetector 40 outputs a signal indicating the intensity of the interference light. This signal is called a beat signal. The frequency of the beat signal, i.e., the beat frequency, is equal to the difference between the above frequencies. The second processing circuit 52b can generate distance information of the object from the beat frequency.

[0116] FIG. 11B is a diagram schematically illustrating the time change in the frequency of the reference light and the reflected light 20Lb when an object approaches the measurement device 60B. When an object approaches, the frequency of the reflected light 20Lb shifts upward along the frequency axis due to Doppler shift compared to when the object is stationary. The amount of frequency shift of the reflected light 20Lb depends on the component of the object's velocity vector projected toward the reflected light 20Lb. The beat frequencies of the reference light and the reflected light 20Lb differ between the up-chirp period and the down-chirp period. In the example shown in FIG. 11B , the beat frequencies in the down-chirp period of both are higher than the beat frequencies in the up-chirp period of both. The second processing circuit 52b can generate velocity information of the object from the difference in beat frequency due to Doppler shift. Furthermore, the second processing circuit 52b can generate distance information of the object from the average value of the beat frequencies in the up-chirp period and the down-chirp period.

[0117] [Example of Measurement Operation] In the second embodiment, the FMCW method can simultaneously acquire distance information and velocity information for each measurement point 12. A non-zero velocity indicates a relative change in the positional relationship between the measurement device 60B and an object in the target area 10. In other words, a non-zero velocity indicates that an object is moving in the target area 10 or that the measurement device 60B is vibrating. Both of these can be disturbances during measurement. When the velocity at a measurement point 12 is non-zero, the disturbance period is a period that includes the measurement time at the current measurement point 12 but does not include measurement times at other measurement points 12. This period can be, for example, from the time obtained by subtracting a predetermined time from the measurement time at the current measurement point 12 to the time obtained by adding a predetermined time to the measurement time. The predetermined time can be, for example, a time shorter than half the measurement time per measurement point 12.

[0118] Fig. 12 is a flowchart that schematically illustrates an example of a measurement operation performed by the processing circuitry 50 in embodiment 2. The measurement operation illustrated in Fig. 12 differs from the measurement operation illustrated in Fig. 5 in the following respects. That is, the processing circuitry 50 performs the operations of steps S2050 to S2070 instead of steps S1050 to S1070 and S1100 to S1120 illustrated in Fig. 5.

[0119] <Step S2050> The control circuit 54 controls the light source 20, the scanner 30, and the photodetector 40 to cause the measurement device 60B to perform measurement.

[0120] <Step S2060> The second processing circuit 52b calculates the distance and speed at the measurement point 12 based on the detection signal.

[0121] <Step S2070> The first processing circuit 52a determines whether the velocity at the measurement point 12 measured by the measurement device 60B is non-zero. The velocity at the measurement point 12 is a velocity in polar coordinates. If the absolute value of the velocity at the measurement point 12 is higher than a predetermined reference velocity, the velocity is determined to be non-zero. The predetermined reference velocity may be, for example, the maximum absolute value of stationary noise when measuring the velocity of a stationary object. In this case, erroneous determination due to stationary noise can be prevented.

[0122] If the determination is yes, the control circuit 54 executes the operation of step S1030. If the determination is no, the first processing circuit 52a executes the operation of step S1090. In step S1090, the first processing circuit 52a converts the polar coordinates into Cartesian coordinates and stores the measurement data exemplified in FIG. 4B in the memory 56.

[0123] 12, measurement data from which disturbances have been removed can be efficiently acquired, similar to the measurement operation shown in Fig. 5. Furthermore, the presence or absence of disturbances can be accurately determined for each measurement point 12 based on the speed, making it easier to remove disturbances. Also, the possibility of erroneously removing measurement data that is not affected by disturbances can be reduced.

[0124] (Variation 1 of Embodiment 2) In Variation 1 of Embodiment 2, measurement data affected by disturbances is not displayed but is stored in memory 56. If measurement data affected by disturbances is displayed, the visibility of point clouds not affected by the disturbances decreases. In Variation 1 of Embodiment 2, measurement data affected by disturbances is not displayed, so the decrease in visibility can be prevented, and measurement data that allows post-processing is still retained.

[0125] FIG. 13 is a flowchart that schematically illustrates an example of a measurement operation performed by the processing circuitry 50 in Modification 1 of Embodiment 2. The measurement operation illustrated in FIG. 13 differs from the measurement operation illustrated in FIG. 12 in the following three points. First, the processing circuitry 50 does not perform the operation of step S2070 illustrated in FIG. 12. Second, the processing circuitry 50 performs the operation of step S2090 instead of step S1090 illustrated in FIG. 12 after step S2060. Third, the processing circuitry 50 performs the operation of step S1141 instead of step S1140 illustrated in FIG. 12. The operation of step S1141 has been described with reference to FIG. 6.

[0126] <Step S2090> The first processing circuit 52a stores the measurement data illustrated in FIG. 10B in the memory 56. This measurement data includes, for each measurement point 12, the measurement time, coordinates, irradiation direction and distance, and velocity as a disturbance. The coordinates are converted from polar coordinates to Cartesian coordinates. Instead of velocity, a code indicating a disturbance may be used, as shown in FIG. 4C. In this case, the disturbance period is a period that includes the measurement time at the current measurement point 12 but does not include measurement times at other measurement points 12. In this way, the first processing circuit 52a uses velocity or a code indicating a disturbance to store the measurement data in the memory 56, in which data within the disturbance period and data outside the disturbance period are distinguished.

[0127] The measurement operation shown in Fig. 13 makes it possible to efficiently obtain measurement data from which disturbances have been removed, similar to the measurement operation shown in Fig. 12. Furthermore, post-processing of the measurement data is also possible.

[0128] (Second Modification of Second Embodiment) In a second modification of the second embodiment, measurement data not stored in the memory 56 during a disturbance period is interpolated using measurement data outside the disturbance period.

[0129] 14A is a flowchart schematically illustrating an example of a measurement operation performed by the processing circuitry 50 in Modification 2 of Embodiment 2. The measurement operation illustrated in Fig. 14A differs from the measurement operation illustrated in Fig. 12 in the following respects. That is, the processing circuitry 50 performs the operation of step S2150 after step S1030.

[0130] <Step S2150> When the first processing circuit 52a determines that the measurement based on the scan plan has ended, it interpolates the measurement data that has not been stored in the memory 56 during the disturbance period using the measurement data at nearby measurement points 12.

[0131] Fig. 14B is a flowchart that schematically illustrates an example of the processing operation performed by the processing circuitry 50 in step S2150 shown in Fig. 14A. The processing circuitry 50 performs the operations of steps S1451, S1152, S1153, S2154, and S2156 shown in Fig. 14B. The operation of step S1451 has been described with reference to Fig. 9B. The operations of steps S1152 and S1153 have been described with reference to Fig. 7B.

[0132] <Step S2154> The first processing circuit 52a extracts, from the measurement data stored in the memory 56, measurement data whose irradiation direction is similar to that of the measurement data selected in step S1153. The absolute value of the difference between the irradiation angle at the measurement point 12 of the measurement data stored in the memory 56 and the irradiation angle at the measurement point 12 of the measurement data selected in step S1153 may be, for example, equal to or less than a predetermined reference angle. Here, three measurement data are extracted in order of decreasing proximity to the irradiation direction. The number of extracted measurement data may be one or two, or may be four or more.

[0133] <Step S2156> The first processing circuit 52a interpolates the measurement data selected in step S1153 using the above three measurement data. In this interpolation, the difference between the irradiation angle of the measurement data stored in memory 56 and the irradiation angle of the measurement data selected in step S1153 is weighted, and the distances of the three measurement data are averaged. The first processing circuit 52a converts polar coordinates into Cartesian coordinates and stores the interpolated measurement data in memory 56. Note that if one measurement data with a similar irradiation direction is extracted in step S2154, the measurement data selected in step S1153 is replaced with this one measurement data.

[0134] 14B , measurement data not stored in memory 56 during the disturbance period can be interpolated using measurement data from outside the disturbance period. If measurement data is not stored during the disturbance period, a bias in the spatial density of the measurement data may occur. Interpolating the measurement data can prevent such a bias.

[0135] (Third Modification of Second Embodiment) In a third modification of the second embodiment, measurement data affected by a disturbance is interpolated using measurement data not affected by the disturbance.

[0136] 15A is a flowchart schematically illustrating an example of a measurement operation performed by the processing circuitry 50 in Modification 3 of Embodiment 2. The measurement operation illustrated in Fig. 15A differs from the measurement operation illustrated in Fig. 13 in the following respects. That is, the processing circuitry 50 performs the operation of step S2160 after step S1030.

[0137] <Step S2160> When the first processing circuit 52a determines that the measurement based on the scan plan has ended, it interpolates the measurement data affected by the disturbance with the measurement data at a nearby measurement point 12 that is not affected by the disturbance.

[0138] Fig. 15B is a flowchart that schematically illustrates an example of the processing operation performed by the processing circuitry 50 in step S2160 shown in Fig. 15A. The processing circuitry 50 performs the operations of steps S1151 to S1153, S2154, and S2156 shown in Fig. 15B. The operations of steps S1151 to S1153 have been described with reference to Fig. 7B. The operations of steps S2154 and S2156 have been described with reference to Fig. 14B.

[0139] The processing operation shown in Fig. 15B differs from the processing operation shown in Fig. 14B in the following respects. That is, the processing circuit 50 executes the operation of step S1151 instead of step S1451. Specifically, the first processing circuit 52a extracts measurement data to which a code indicating a disturbance is attached. When a speed is stored in the memory 56 instead of a code indicating the presence or absence of a disturbance, the first processing circuit 52a may extract measurement data whose absolute value of the speed is higher than a predetermined reference speed.

[0140] 15B, measurement data affected by disturbances can be interpolated using measurement data that is not affected by the disturbances. Deleting measurement data affected by disturbances can cause bias in the spatial density of the measurement data. Interpolating the measurement data can prevent such bias.

[0141] (Embodiment 3) [Measurement System] Below, with reference to Fig. 16A , an example configuration of a measurement system according to embodiment 3 of the present disclosure will be described. In this measurement system, vibration of a measurement device is detected as a disturbance. The measurement device may vibrate, for example, when the measurement device is mounted on a drone, when a user performs measurements while holding the measurement device in their hands, or when the measurement device is used in a place with a lot of vibration, such as a construction site.

[0142] Fig. 16A is a block diagram schematically showing the configuration of a measurement system according to a third exemplary embodiment of the present disclosure. The measurement system 100C shown in Fig. 16A differs from the measurement system 100A shown in Fig. 4A in the following respects. That is, the measurement system 100C includes a vibration sensor 70 that detects vibrations of the measurement device 60A, in addition to the measurement device 60A, first processing circuit 52a, and control circuit 54 shown in Fig. 4A. The measurement device 60A may be replaced with the measurement device 60B shown in Fig. 10A.

[0143] The vibration sensor 70 can detect vibrations at a constant measurement period, for example. This measurement period is sufficiently shorter than one unit of the measurement operation described above in the measurement device 60A. This measurement period may be shorter or longer than the measurement time per measurement point 12.

[0144] In the third embodiment, it is assumed that the position and orientation of the measurement device 60A do not change due to vibration. If the position and orientation of the measurement device 60A change due to vibration, the measurement system 100A may further include another sensor that detects the position and orientation of the measurement device 60A. The position and orientation of the measurement device 60A are corrected based on the detection results of the other sensor.

[0145] [Example of Measurement Data] The measurement data stored in the memory 56 in the third embodiment may be the same as the measurement data shown in Figures 4B and 4C. Alternatively, the measurement data stored in the memory 56 in the third embodiment may include the amplitude of vibration.

[0146] 16B is a diagram showing an example of measurement data stored in memory 56 in embodiment 3. The measurement data shown in FIG. 16B differs from the measurement data shown in FIG. 4C in the following respects. That is, the measurement data includes the amplitude of vibration instead of a code indicating the presence or absence of a disturbance. The amplitude of vibration is stored at measurement point 12 where a disturbance has occurred.

[0147] [Example of Measurement Operation] In the third embodiment, vibrations of the measurement device 60A can be detected by the vibration sensor 70. However, moving objects in the target area 10 cannot be detected.

[0148] Fig. 17 is a flowchart that schematically illustrates an example of a measurement operation performed by the processing circuitry 50 in embodiment 3. The measurement operation illustrated in Fig. 17 differs from the measurement operation illustrated in Fig. 5 in the following respects. That is, the processing circuitry 50 performs the operations of steps S3060 and S3070 instead of steps S1060 and S1070 illustrated in Fig. 5.

[0149] <Step S3060> The first processing circuit 52a acquires the most recent vibration measurement result from the vibration sensor 70 immediately after the measurement at the measurement point 12 by the measuring device 60A. Alternatively, the first processing circuit 52a may acquire the vibration measurement result from the vibration sensor 70 immediately before the measurement at the measurement point 12 by the measuring device 60A. Furthermore, the vibration sensor 70 may measure vibration in response to an instruction signal input from the first processing circuit 52a. In this case, the vibration is measured immediately before, immediately after, or simultaneously with the measurement at the measurement point 12 by the measuring device 60A.

[0150] The disturbance period may be, for example, from the time when the vibration sensor 70 makes a measurement immediately before the measurement time at the current measurement point 12 to the time when the vibration sensor 70 makes a measurement immediately after the measurement time at the current measurement point 12. In this case, the length of the disturbance period can be determined based on the measurement cycle at which the vibration sensor 70 detects vibrations.

[0151] If the vibration measurement period is shorter than the measurement time per measurement point 12, the disturbance period includes the measurement time at the current measurement point 12, but does not include the measurement times at other measurement points 12. If the vibration measurement period is longer than the measurement time per measurement point 12, depending on the vibration measurement period, the disturbance period may include not only the measurement time at the current measurement point 12, but also the measurement time at the measurement point 12 to be measured in the future. In this case, the first processing circuit 52a may execute the operation of step S1060 shown in FIG. 5 between step S1050 and step S3060, and may not store the measurement data at the measurement point 12 to be measured in the future in the memory 56.

[0152] <Step S3070> The first processing circuit 52a determines whether or not vibration has occurred based on the vibration measurement results. If vibration has occurred before a predetermined time has elapsed since the measurement time at the current measurement point 12, the first processing circuit 52a determines that a disturbance has occurred at the measurement time at the current measurement point 12. The predetermined time may be, for example, a time shorter than the measurement time per measurement point 12. Therefore, it is possible to accurately determine whether or not a disturbance has occurred at the current measurement point 12.

[0153] If the determination is yes, the control circuit 54 executes the operation of step S1030. If the determination is no, the second processing circuit 52b executes the operation of step S1070.

[0154] 17, measurement data from which disturbances have been removed can be efficiently acquired, similar to the measurement operation shown in Fig. 5. Furthermore, since the presence or absence of disturbances can be accurately determined for each measurement point 12 based on vibration, it becomes easier to remove the disturbances. In addition, it is possible to reduce the possibility of erroneously removing measurement data that is not affected by disturbances.

[0155] (Variation 1 of Embodiment 3) In Variation 1 of Embodiment 3, measurement data affected by disturbances is not displayed but is stored in memory 56. If measurement data affected by disturbances is displayed, the visibility of point clouds not affected by the disturbances decreases. In Variation 1 of Embodiment 3, measurement data affected by disturbances is not displayed, so the decrease in visibility can be prevented, and measurement data that allows post-processing is still retained.

[0156] FIG. 18 is a flowchart that schematically illustrates an example of a measurement operation performed by the processing circuit 50 in Modification 1 of Embodiment 3. The measurement operation illustrated in FIG. 18 differs from the measurement operation illustrated in FIG. 17 in the following three points. First, the processing circuit 50 performs the operations of steps S1070 and S3071 in this order after step S3060. Second, if the determination in step S3071 is yes, the processing circuit 50 performs the operation of step S3170. Third, the processing circuit 50 performs the operation of step S1141 instead of step S1140 illustrated in FIG. 17. The operation of step S1141 has been described with reference to FIG. 6.

[0157] <Step S3071> The first processing circuit 52a determines whether or not vibration has occurred based on the vibration measurement results. If the determination is yes, the first processing circuit 52a executes the operation of step S3170. If the determination is no, the first processing circuit 52a executes the operation of step S1090.

[0158] <Step S3170> The first processing circuit 52a stores the measurement data illustrated in FIG. 16B in the memory 56. This measurement data includes, for each measurement point 12, the measurement time, coordinates, irradiation direction and distance, and vibration amplitude as a disturbance. Instead of the vibration amplitude, a code indicating the disturbance may be used, as shown in FIG. 4C. In this way, the first processing circuit 52a uses the vibration amplitude or the code indicating the disturbance to store the measurement data in the memory 56, in which data within the disturbance period and data outside the disturbance period are distinguished.

[0159] The measurement operation shown in Fig. 18 makes it possible to efficiently obtain measurement data from which disturbances have been removed, similar to the measurement operation shown in Fig. 17. Furthermore, post-processing of the measurement data is also possible.

[0160] (Second Modification of Third Embodiment) In a second modification of the third embodiment, measurement data not stored in the memory 56 during a disturbance period is interpolated using measurement data outside the disturbance period.

[0161] 19A is a flowchart schematically illustrating an example of a measurement operation performed by the processing circuitry 50 in Modification 2 of Embodiment 3. The measurement operation illustrated in FIG. 19A differs from the measurement operation illustrated in FIG. 17 in the following respects. That is, the processing circuitry 50 performs the operation of step S3150 after step S1030.

[0162] <Step S3150> When the first processing circuit 52a determines that the measurement based on the scan plan has ended, it interpolates the measurement data that has not been stored in the memory 56 during the disturbance period using the measurement data at nearby measurement points 12.

[0163] Fig. 19B is a flowchart that schematically illustrates an example of the processing operation performed by the processing circuitry 50 in step S3150 shown in Fig. 19A. The processing circuitry 50 performs the operations of steps S1451, S1152, S1153, S2154, and S2156 shown in Fig. 19B. The operation of step S1451 has been described with reference to Fig. 9B. The operations of steps S1152 and S1153 have been described with reference to Fig. 7B. The operations of steps S2154 and S2156 have been described with reference to Fig. 14B.

[0164] 19B , measurement data not stored in memory 56 during the disturbance period can be interpolated using measurement data not affected by the disturbance during periods other than the disturbance period. If measurement data is not stored during the disturbance period, a bias in the spatial density of the measurement data can occur. Interpolating the measurement data can prevent such a bias.

[0165] (Third Modification of Third Embodiment) In a third modification of the third embodiment, measurement data affected by a disturbance is interpolated using measurement data not affected by the disturbance.

[0166] 20A is a flowchart schematically illustrating an example of a measurement operation performed by the processing circuitry 50 in Modification 3 of Embodiment 3. The measurement operation illustrated in Fig. 20A differs from the measurement operation illustrated in Fig. 18 in the following respects. That is, the processing circuitry 50 performs the operation of step S3160 after step S1030.

[0167] <Step S3160> When the first processing circuit 52a determines that the measurement based on the scan plan has ended, it interpolates the measurement data affected by the disturbance with the measurement data at a nearby measurement point 12 that is not affected by the disturbance.

[0168] Fig. 20B is a flowchart that schematically illustrates an example of the processing operation performed by the processing circuitry 50 in step S3160 shown in Fig. 20A. The processing circuitry 50 performs the operations of steps S1151 to S1153, S2154, and S2156 shown in Fig. 20B. The operations of steps S1151 to S1153 have been described with reference to Fig. 7B. The operations of steps S2154 and S2156 have been described with reference to Fig. 14B.

[0169] The processing operation shown in FIG. 20B differs from the processing operation shown in FIG. 19B in the following respects. That is, the processing circuit 50 executes the operation of step S1151 instead of step S1451 shown in FIG. 19B. Specifically, the first processing circuit 52a extracts measurement data to which a code indicating a disturbance is attached. When the amplitude of vibration is stored in the memory 56 instead of the code indicating the presence or absence of a disturbance, the first processing circuit 52a may extract measurement data in which the amplitude of vibration is greater than a predetermined amplitude. The predetermined amplitude may be, for example, the maximum value of stationary noise when measuring the amplitude of vibration.

[0170] 20B, measurement data affected by disturbances can be interpolated using measurement data that is not affected by the disturbances. Deleting measurement data affected by disturbances can cause bias in the spatial density of the measurement data. Interpolating the measurement data can prevent such bias.

[0171] (Embodiment 4) [Measurement System] A measurement system according to exemplary embodiment 4 of the present disclosure has a configuration similar to that of the measurement system 100A according to exemplary embodiment 1 of the present disclosure. However, the measurement system according to embodiment 4 differs from the measurement system 100A in the following two points.

[0172] The first point is that the measurement device 60A randomly scans the target area 10 by changing the irradiation direction irregularly. In a random scan, similar to a Lissajous scan, two nearby measurement points 12 are close to each other in space but not in time. Here, "two measurement points 12 are close to each other" means that the absolute value of the difference in the irradiation angles of the two measurement points 12 is smaller than a predetermined reference angle. The predetermined reference angle can be determined, for example, based on the spatial density of the measurement points 12 during measurement and the variance of the irradiation angle per time.

[0173] The second advantage is that the scanner 30 is a mechanism-less scanner that does not perform any mechanical operation. A mechanism-less scanner facilitates random scanning. An example of a mechanism-less scanner is the two-dimensional scanner disclosed in Japanese Patent Application Laid-Open No. 2018-128663. This two-dimensional scanner includes a plurality of slow-light waveguides and a plurality of phase shifters that are respectively connected directly or indirectly to the plurality of slow-light waveguides. Each slow-light waveguide extends along a first direction, and the plurality of slow-light waveguides are arranged along a second direction that intersects the first direction.

[0174] The slow-light waveguide includes two mirrors, a light guide layer containing a liquid crystal material and positioned between the two mirrors, and a pair of electrodes for applying a voltage to the liquid crystal material. In each slow-light waveguide, light propagating through the light guide layer in a first direction is multiple-reflected by the two mirrors and emitted from one or both of the mirrors. By applying a voltage to the pair of electrodes to change the refractive index of the liquid crystal material contained in the light guide layer, the direction of the light beam emitted from the slow-light waveguide changes along the first direction.

[0175] The plurality of light beams respectively output from the plurality of slow-light waveguides form interference beams, and the directions of the interference beams output from the plurality of slow-light waveguides are changed along a second direction by changing the phases of the light input to the plurality of slow-light waveguides by the plurality of phase shifters.

[0176] The two-dimensional scanner described above enables biaxial scanning without mechanical movement. The entire disclosure of JP 2018-128663 A is incorporated by reference.

[0177] [Example of Measurement Data] The measurement data stored in the memory 56 in the fourth embodiment may be the same as the measurement data shown in FIGS. 4B and 4C, for example.

[0178] [Example of Measurement Operation] Next, an example of measurement operation performed by the processing circuitry 50 in the measurement system according to embodiment 4 will be described with reference to Fig. 21A. Fig. 21A is a flowchart that schematically shows an example of measurement operation performed by the processing circuitry 50 in embodiment 4. The measurement operation shown in Fig. 21A differs from the measurement operation shown in Fig. 5 in the following respects. That is, the processing circuitry 50 performs the operation of step S4020 instead of step S1020 shown in Fig. 5.

[0179] <Step S4020> The first processing circuitry 52a sets a scan plan for randomly scanning the target region 10 and transmits the scan plan to the control circuitry 54. In the scan plan, irradiation directions can be determined in random order based on, for example, the number of measurement points 12, the measurement range, and the scan speed of the scanner 30.

[0180] In random scanning, the irradiation direction changes randomly, so the time width from one measurement point 12 to measuring a neighboring measurement point 12 is indefinite. Therefore, in step S1110, a period that includes the measurement time at the current measurement point 12 and has a predetermined time width is used as the disturbance period. This period can be, for example, from the time obtained by subtracting half of the predetermined time width from the measurement time to the time obtained by adding half of the predetermined time width to the measurement time. The predetermined time width can be set based on, for example, the following conditions: The time required for people such as pedestrians and workers, or animals or other living beings, to pass through the target area 10. The time required for vehicles such as passing cars, work vehicles, heavy machinery, bicycles, and other mobility vehicles to pass through the target area 10. The time required for arms of cranes, heavy machinery, and robots to cross the target area 10. The duration of vibrations caused by the operation of heavy machinery. The duration of vibrations when a structure is demolished, collapsed, or dropped. The continuous movement time of mobile bodies that move and are equipped with the measurement system according to embodiment 4, such as arms of cranes, heavy machinery, and robots, and mobile robots.

[0181] Fig. 21B is a flowchart outlining an example of the processing operation performed by the processing circuitry 50 in step S4020 shown in Fig. 21A. The operations of steps S4021 to S4025 shown in Fig. 21B are performed.

[0182] <Step S4021> The first processing circuit 52a determines the number of measurement points 12 in one unit of the above-mentioned measurement operation. The number of measurement points 12 may be determined before the measurement, or may be input by the user via an input device (not shown).

[0183] <Step S4022> The first processing circuit 52a determines the angular ranges in the X and Y directions as the range of the target region 10 in one unit of the measurement operation. The angular ranges in the X and Y directions may be determined before the measurement or may be input by the user via an input device (not shown).

[0184] <Step S4023> The first processing circuit 52a determines the number of measurement points 12 determined in step S4021 and the arrangement of irradiation angles for comprehensively measuring the angular range determined in step S4022. In one unit of measurement operation, the irradiation directions of the measurement points 12 are all different. For example, when measuring an angular range of 50° in the X direction and 50° in the Y direction using 20,000 measurement points 12, 200 points are set at intervals of 0.251° in the X direction and 100 points are set at intervals of 0.505° in the Y direction. 20,000 types of irradiation directions are determined as the irradiation directions in one unit of measurement operation.

[0185] <Step S4024> The first processing circuit 52a arranges the irradiation directions determined in step S4023 in a random order. The first processing circuit 52a further stores the determined sequence of measurement orders as a scan plan in the memory 56. Here, since measurements are performed in different irradiation directions in one unit of measurement operation, for example, the measurement results obtained by performing measurements in 20,000 different irradiation directions over 20,000 measurements are treated as one unit of measurement operation.

[0186] <Step S4025> The first processing circuitry 52a transmits the scan plan to the control circuitry 54.

[0187] The measurement operation shown in FIG. 21A makes it possible to efficiently acquire measurement data from which disturbances have been removed, similar to the measurement operation shown in FIG.

[0188] In the fourth embodiment, modifications similar to the first to fourth modifications of the first embodiment are possible.

[0189] (Post-Processing of Measurement Data) In the modified examples of the above-described embodiments, post-processing of measurement data may be modified as follows.

[0190] Modification 1: Post-processing is performed for each measurement operation unit, but it may be performed for multiple measurement operation units at once. In this case, a group of parameters used to convert polar coordinates including irradiation direction and distance into Cartesian coordinates is stored in memory 56 in association with the measurement data. The group of parameters may include, for example, the origin position of the polar coordinates and an expression in Cartesian coordinates.

[0191] Modification 2: Post-processing may be performed by a third processing circuit different from the first processing circuit 52a. The third processing circuit may be included in a data processing device different from the measurement system according to each embodiment. The measurement results may be exchanged between the measurement systems 100A to 100C and the data processing device via wired or wireless communication, or via a dedicated or general network. Alternatively, the measurement results may be exchanged between the measurement systems 100A to 100C and the data processing device via a memory 56 detached from the measurement systems 100A to 100C, or via a storage medium to which data has been written from the memory 56.

[0192] FIG. 22A is a block diagram schematically illustrating another configuration of a measurement system according to the first exemplary embodiment of the present disclosure, and a data processing device for post-processing measurement data. The measurement system 100A1 shown in FIG. 22A includes a measurement device 60A, a first processing circuit 52a, a control circuit 54, a first memory 56a, and a transmitter 82. The data processing device 80 shown in FIG. 22A includes a third processing circuit 52c, a second memory 56b, and a receiver 84. The third processing circuit 52c may be treated as part of the processing circuit 50. In the measurement system 100A1, the transmitter 82 transmits data stored in the first memory 56a and data output from the control circuit 54 to the receiver 84. In the data processing device 80, the receiver 84 receives the data transmitted from the transmitter 82.

[0193] When the target region 10 is a wide-ranging three-dimensional space, such as a large building, a large amount of measurement data is generated by changing the position and orientation of the measurement device 60A. Post-processing and storage of the large amount of measurement data may be performed in the data processing device 80. In the data processing device 80, the third processing circuit 52c performs post-processing of the large amount of measurement data and stores the post-processed large amount of measurement data in the second memory 56b. The data processing device 80 can reduce the processing load on the measurement system 100A1.

[0194] Modification 3 In post-processing, the average value of the measurement times at the nearby measurement points 12 used for the interpolation, down to the second, may be stored in the memory 56 as the measurement time of the measurement data interpolated using the measurement data at the nearby measurement points 12. Alternatively, the earliest or latest measurement time among the measurement times at the nearby measurement points 12 used for the interpolation may be stored in the memory 56. Furthermore, times related to the measurement data at the nearby measurement points 12 used for the interpolation, such as the start time and end time of one unit of the measurement operation, may also be stored in the memory 56.

[0195] Fig. 22B is a diagram showing an example of post-processed measurement data stored in memory 56. As shown in Fig. 22B, the measurement time of the post-processed measurement data is the average value, down to the second, of the measurement times of the measurement data at the nearby measurement points 12 used for interpolation. Measurement data flagged with "1" as a disturbance is post-processed measurement data.

[0196] [Additional Notes] The above description of the embodiments discloses the following techniques.

[0197] [Technology 1] A measurement system comprising: a light source that emits illumination light to illuminate a target area; a scanner that changes the illumination angle of the illumination light; a photodetector that detects reflected light from the target area and outputs a detection signal; a processing circuit that drives the scanner to perform a Lissajous scan of the target area to illuminate the target area with the illumination light and generates measurement data based on the detection signal; and a memory that stores the measurement data, wherein the processing circuit stores in the memory the measurement data from which data within a disturbance period determined based on a disturbance during measurement has been removed, or the measurement data from which data within the disturbance period and data outside the disturbance period have been distinguished.

[0198] This measurement system can efficiently acquire measurement data from which disturbances have been removed, based on the measurement results obtained by performing a Lissajous scan on the target region.

[0199] [Technology 2] The measurement system according to Technology 1, wherein the target area includes a plurality of measurement points each irradiated with the irradiation light, the plurality of measurement points including a first measurement point and a second measurement point, a first measurement time at the first measurement point is earlier than a second measurement time at the second measurement point, an absolute value of a difference between a first irradiation angle at the first measurement point and a second irradiation angle at the second measurement point is smaller than a predetermined reference angle, and the disturbance period includes a first period from the first measurement time to the second measurement time and a second period from the second measurement time that is shorter than the first period.

[0200] In this measurement system, the disturbance period can be determined based on the measurement times at the first and second measurement points located nearby.

[0201] [Technology 3] The measurement system according to Technology 2, wherein the predetermined reference angle is an absolute value of a difference between an irradiation angle at the second measurement point and an irradiation angle at a measurement point measured next to the second measurement point in the Lissajous scan.

[0202] In this measurement system, the first measurement point is closer to the second measurement point than the measurement point that is measured next to the second measurement point.

[0203] [Technology 4] The measurement system according to Technology 2 or 3, wherein the measurement data includes information about distance, and an absolute value of a difference between the distance at the first measurement point and the distance at the second measurement point is greater than a predetermined reference distance.

[0204] In this measurement system, it is apparent that a disturbance has occurred due to a difference in distance between the first and second measurement points.

[0205] [Technology 5] The measurement system according to Technology 4, wherein the predetermined reference distance is a maximum absolute value of stationary noise when measuring distance.

[0206] This measurement system can prevent erroneous determinations caused by stationary noise when determining the presence or absence of disturbance based on the distance deviation.

[0207] [Technology 6] The measurement system according to Technology 1, wherein the target area includes a plurality of measurement points each irradiated with the irradiation light, the measurement data includes information about speed, and the disturbance period is a period including measurement times at measurement points among the plurality of measurement points where the absolute value of the speed is higher than a predetermined reference speed.

[0208] This measurement system can accurately determine the presence or absence of disturbance at each measurement point based on the speed, making it easy to remove disturbances.

[0209] [Technology 7] The measurement system according to Technology 6, wherein the predetermined reference velocity is a maximum absolute value of stationary noise when measuring the velocity of a stationary object.

[0210] This measurement system can prevent false detections caused by stationary noise when determining the presence or absence of disturbances based on speed.

[0211] [Technology 8] The measurement system according to Technology 1, further comprising a vibration sensor that detects vibration as the disturbance.

[0212] This measurement system can detect vibration as a disturbance.

[0213] [Technology 9] The measurement system described in Technology 8, wherein the target area includes a plurality of measurement points each irradiated with the irradiation light, and when the vibration occurs before a predetermined time has elapsed from a measurement time at a certain measurement point among the plurality of measurement points, the processing circuit determines that the disturbance occurred at the measurement time at the certain measurement point.

[0214] This measurement system can accurately determine whether or not a disturbance exists at a measurement point.

[0215] [Technology 10] The measurement system according to Technology 9, wherein the disturbance period is from a time when a measurement is made by the vibration sensor immediately before the measurement time at the certain measurement point to a time when a measurement is made by the vibration sensor immediately after the measurement time at the certain measurement point.

[0216] In this measurement system, the length of the disturbance period can be determined based on the measurement cycle at which the vibration sensor detects vibration.

[0217] [Technology 11] The measurement system according to any one of Techniques 1 to 10, wherein the target area includes a plurality of measurement points each irradiated with the irradiation light, the plurality of measurement points including a third measurement point within the disturbance period and at least one fourth measurement point outside the disturbance period, and the processing circuit replaces or interpolates measurement data at the third measurement point with measurement data at the at least one fourth measurement point.

[0218] In this measurement system, deviations that may occur in the spatial density of the measurement data can be prevented by replacing or interpolating the measurement data.

[0219] [Technology 12] The measurement system according to Technology 11, wherein an absolute value of a difference between the irradiation angle at the third measurement point and the irradiation angle at the at least one fourth measurement point is smaller than a predetermined reference angle.

[0220] In this measurement system, the third measurement point and at least one fourth measurement point are located nearby.

[0221] [Technology 13] The measurement system according to technologies 11 and 12, wherein the third measurement point and the at least one fourth measurement point are included in the same unit of measurement operation that repeatedly scans the target area.

[0222] This measurement system allows for processing of measurement data within the same unit of measurement operation.

[0223] [Technology 14] The measurement system according to any one of Techniques 1 to 5, wherein the target area includes a plurality of measurement points each illuminated with the illumination light, the plurality of measurement points including a third measurement point within the disturbance period and a fourth measurement point outside the disturbance period, an absolute value of a difference between an illumination angle at the third measurement point and an illumination angle at the fourth measurement point is smaller than a predetermined reference angle, the measurement data includes information related to distance, and the processing circuit compares the measurement data at the third measurement point with the measurement data at the fourth measurement point, and when the absolute value of the difference between the distance at the third measurement point and the distance at the fourth measurement point is equal to or smaller than a predetermined reference distance, stores the measurement data at the third measurement point within the disturbance period as normal measurement data in the memory.

[0224] This measurement system can correct erroneous determinations of disturbances.

[0225] [Technology 15] The measurement system according to Technology 14, wherein the third measurement point and the fourth measurement point are included in the same unit of measurement operation that repeatedly scans the target area.

[0226] This measurement system allows for processing of measurement data within the same unit of measurement operation.

[0227] The technology of the present disclosure can be applied to applications that require the creation or updating of maps, such as self-location estimation for autonomously moving objects.

[0228] 10 Target area 12 Measurement point 20 Light source 20La Irradiation light 20Lb Reflected light 30 Scanner 40 Photodetector 50 Processing circuit 52a First processing circuit 52b Second processing circuit 52c Third processing circuit 54 Control circuit 56 Memory 56a First memory 56b Second memory 60A, 60B Measurement device 62 Optical interference system 70 Vibration sensor 80 Data processing device 82 Transmitter 84 Receiver 100A, 100A1, 100B, 100C Measurement system

Claims

a light source that emits illumination light for illuminating a target area; a scanner that changes the irradiation angle of the irradiation light; a photodetector that detects reflected light from the target area and outputs a detection signal; a processing circuit that drives the scanner to perform a Lissajous scan of the target area, irradiating the target area with the irradiation light, and generates measurement data based on the detection signal; a memory for storing the measurement data; Equipped with the processing circuit stores in the memory the measurement data from which data within a disturbance period determined based on a disturbance during measurement has been removed, or the measurement data from which data within the disturbance period has been distinguished from data outside the disturbance period. Measurement system. 　 the target area includes a plurality of measurement points each irradiated with the irradiation light, the plurality of measurement points including a first measurement point and a second measurement point; a first measurement time at the first measurement point is earlier than a second measurement time at the second measurement point, and an absolute value of a difference between a first irradiation angle at the first measurement point and a second irradiation angle at the second measurement point is smaller than a predetermined reference angle; the disturbance period includes a first period from the first measurement time to the second measurement time and a second period from the second measurement time that is shorter than the first period; The measurement system of claim 1 . 　 the predetermined reference angle is an absolute value of a difference between an irradiation angle at the second measurement point and an irradiation angle at a measurement point measured next to the second measurement point in the Lissajous scan. The measurement system of claim 2 . 　 the measurement data includes information about distance; an absolute value of the difference between the distance at the first measurement point and the distance at the second measurement point is greater than a predetermined reference distance; The measurement system of claim 2 . 　 The predetermined reference distance is the maximum absolute value of stationary noise when measuring distance. The measurement system according to claim 4 . 　 the target area includes a plurality of measurement points each illuminated with the illumination light; the measurement data includes information regarding velocity; the disturbance period is a period including a measurement time at a measurement point among the plurality of measurement points where the absolute value of the speed is higher than a predetermined reference speed; The measurement system of claim 1 . 　 The predetermined reference velocity is the maximum absolute value of stationary noise when measuring the velocity of a stationary object. The measurement system of claim 6 . 　 Further provided is a vibration sensor for detecting vibration as the disturbance. The measurement system of claim 1 . 　 the target area includes a plurality of measurement points each illuminated with the illumination light; When the vibration occurs before a predetermined time has elapsed from a measurement time at a certain measurement point among the plurality of measurement points, the processing circuit determines that the disturbance occurred at the measurement time at the certain measurement point. The measurement system of claim 8 . 　 the disturbance period is from a time when the measurement is made by the vibration sensor immediately before the measurement time at the certain measurement point to a time when the measurement is made by the vibration sensor immediately after the measurement time at the certain measurement point; The measurement system of claim 9 . 　 the target area includes a plurality of measurement points each irradiated with the irradiation light, the plurality of measurement points including a third measurement point within the disturbance period and at least one fourth measurement point outside the disturbance period; the processing circuitry replaces or interpolates the measurement data at the third measurement point with the measurement data at the at least one fourth measurement point; The measurement system according to any one of claims 1 to 10. 　 an absolute value of a difference between the irradiation angle at the third measurement point and the irradiation angle at the at least one fourth measurement point is smaller than a predetermined reference angle; The measurement system of claim 11. 　 the third measurement point and the at least one fourth measurement point are included in the same unit of a measurement operation that repeatedly scans the target area. The measurement system of claim 11. 　 the target area includes a plurality of measurement points each irradiated with the irradiation light, the plurality of measurement points including a third measurement point within the disturbance period and a fourth measurement point outside the disturbance period; the absolute value of the difference between the irradiation angle at the third measurement point and the irradiation angle at the fourth measurement point is smaller than a predetermined reference angle; the measurement data includes information about distance; The processing circuitry comparing the measurement data at the third measurement point with the measurement data at the fourth measurement point; When an absolute value of the difference between the distance at the third measurement point and the distance at the fourth measurement point is equal to or less than a predetermined reference distance, the measurement data at the third measurement point during the disturbance period is stored in the memory as normal measurement data. The measurement system according to any one of claims 1 to 5. 　 the third measurement point and the fourth measurement point are included in the same unit of a measurement operation that repeatedly scans the target area. The measurement system of claim 14.

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