Measurement device

Abstract

This measurement device 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; memory; and a processing circuit. The processing circuit drives the scanner in a first mode for Lissajous scanning the target region, causes the target region to be irradiated with the irradiation light, generates point group information on the basis of the detection signal, stores the point group information in the memory, erases or overwrites at least a part of the stored point group information at every first time interval, determines at every second time interval that is shorter than the first time interval whether to switch from the first mode to a second mode on the basis of the point group information stored in the memory, and drives the scanner in the second mode on the basis of the determination results.

Description

Measuring equipment

[0001] The present disclosure relates to a measurement device.

[0002] Conventionally, measurement devices are known that scan a target area with irradiated light to generate distance information for the target area. A typical example of a scanning method is raster scanning, which performs horizontal scanning operations followed by vertical scanning operations. Another example of a scanning method is Lissajous scanning, which simultaneously performs periodic scanning operations in two mutually perpendicular directions. Patent Document 1 discloses an example of a measurement device that generates distance information for a target area using Lissajous scanning.

[0003] JP 2011-053137 A

[0004] The present disclosure provides a measurement device that can more quickly find and scan a region of interest that includes a portion of interest within a target region.

[0005] A measurement device 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 memory, and a processing circuit, wherein the processing circuit drives the scanner in a first mode that performs a Lissajous scan of the target area, illuminating the target area with the illumination light, generating point cloud information based on the detection signal, storing the point cloud information in the memory, erasing or overwriting at least a portion of the stored point cloud information at first time intervals, and determining, at second time intervals shorter than the first time intervals, based on the point cloud information stored in the memory, whether to switch from the first mode to a second mode having scan parameters different from those of the first mode, and driving the scanner in the second mode based on the determination result.

[0006] 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.

[0007] The technology disclosed herein makes it possible to realize a measurement device that can more quickly find and scan a region of interest that includes a portion of interest within a target region.

[0008] FIG. 1A is a block diagram schematically illustrating a configuration of a measurement apparatus according to a first exemplary embodiment of the present disclosure. FIG. 1B is a diagram schematically illustrating an example configuration of a processing device included in the measurement apparatus shown in FIG. 1A. FIG. 2 is a diagram schematically illustrating example point cloud information stored in a memory. FIG. 3 is a diagram for explaining examples of scans in first and second modes. FIG. 4 is a flowchart schematically illustrating a first measurement operation example performed by a processing circuit. FIG. 5 is a diagram for explaining an example of the relationship between an update interval and a determination interval in the first measurement operation example. FIG. 6 is a flowchart schematically illustrating a second measurement operation example performed by a processing circuit. FIG. 7 is a diagram for explaining an example of the relationship between an update interval and a determination interval in the second measurement operation example. FIG. 8A is a block diagram schematically illustrating a configuration of a measurement apparatus according to a second exemplary embodiment of the present disclosure. FIG. 8B is a diagram schematically illustrating an example configuration of a processing device included in the measurement apparatus shown in FIG. 8A. FIG. 9 is a flowchart schematically illustrating a third measurement operation example performed by a processing circuit. FIG. 10A is a diagram illustrating the distribution of irradiation points in a comparative example. Fig. 10B is a diagram showing the distribution of irradiation points in an example. Fig. 10C is a graph showing the relationship between the number of point cloud information stored in memory and the coverage rate for a comparative example and an example. Fig. 11A is a flowchart showing an example of the operation of step S108 executed by the processing circuit in example 1 of the measurement operation. Fig. 11B is a diagram for explaining an example of the operation of determining a region of interest by performing a Lissajous scan on a target region.

[0009] 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.

[0010] 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.

[0011] In this disclosure, "light" refers to electromagnetic waves including not only visible light (wavelength of about 400 nm to about 700 nm), but also ultraviolet light (wavelength of about 10 nm to about 400 nm) and infrared light (wavelength of about 700 nm to about 1 mm). In this specification, ultraviolet light may be referred to as "ultraviolet light," and infrared light may be referred to as "infrared light."

[0012] 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.

[0013] First, the findings that form the basis of this disclosure will be described.

[0014] For example, a measurement device may acquire distance information at multiple irradiation points in a target area as point cloud information by driving a scanner that changes the irradiation angle to scan the target area with irradiation light. In such a measurement device, there is a trade-off between the angular resolution of the irradiation angle and the measurement time required to complete the scan of the target area.

[0015] When the measurement rate, which represents the number of irradiation points per unit time, is constant, lowering the scanner vibration frequency increases the angular resolution but increases the measurement time, whereas increasing the scanner vibration frequency decreases the measurement time but decreases the angular resolution.

[0016] Increasing the measurement rate is one way to improve the angular resolution and shorten the measurement time at the same time, but there are limitations to increasing the measurement rate, such as limitations on the high-frequency modulation characteristics of the intensity and / or frequency of the irradiated light emitted from the light source, and the time required to calculate distance information.

[0017] In the measurement device disclosed in Patent Document 1, a scanner is driven to perform a Lissajous scan of a target area in multiple operating modes. Which of the multiple operating modes is selected is determined based on the presence of an object, the distance to the object, and the movement speed of the measurement target. The multiple operating modes include a normal measurement mode, a detailed measurement mode, and a high-speed measurement mode. In each operating mode, distance information is acquired at all irradiation points in the target area, and then a distance image is generated and output. The distance image is updated every one, multiple, or half a Lissajous scan cycle. Based on the output distance image, objects in the target area are recognized, and information about the object's position and distance is detected.

[0018] On the other hand, in the measurement device disclosed in Patent Document 1, the operating mode is changed after obtaining distance information at all irradiation points within the target area, so it takes time to measure the region of interest (ROI) that includes the part of interest within the target area.

[0019] The present inventors have found the above-mentioned problems and have come up with a measurement device according to an embodiment of the present disclosure that can solve the problems. The measurement device according to the present embodiment will be described below.

[0020] First Embodiment In the following, an example of the configuration of a measurement device according to a first embodiment of the present disclosure will be described, followed by an example of a measurement operation.

[0021] 1A and 1B , a configuration example of a measurement device according to a first embodiment of the present disclosure will be described. The measurement device performs measurements using a time-of-flight (ToF) LiDAR (Light Detecting And Ranging) technique. Instead of the TOF LiDAR technique, a frequency-modulated continuous wave (FMCW) LiDAR technique may be used.

[0022] FIG. 1A is a block diagram schematically illustrating the configuration of a measurement apparatus according to a first exemplary embodiment of the present disclosure. FIG. 1A also illustrates a target area 10 to be measured. The measurement apparatus 100A illustrated in FIG. 1A scans the target area 10 with illumination light 20La to acquire distance information and / or velocity information at a plurality of illumination points 12 within the target area 10 as point cloud information. More specifically, the distance information and / or velocity information at the illumination points 12 is distance information and / or velocity information of an object present at the illumination points 12. In this specification, the distance information and / or velocity information at the illumination points 12 is also simply referred to as "information at the illumination points 12."

[0023] As shown in Fig. 1A, the measurement device 100A includes a light source 20, a scanner 30, a photodetector 40, and a processing device 50. The thick lines with arrows in Fig. 1A represent the flow of light, and the thin lines with arrows represent the flow of signals. Fig. 1B is a diagram schematically showing an example configuration of the processing device 50 included in the measurement device 100A shown in Fig. 1A. As shown in Fig. 1B, the processing device 50 includes a processing circuit 52 and a memory 54 such as a RAM or a flash memory.

[0024] As will be explained in detail later, the measurement device 100A according to embodiment 1 performs measurement in a first mode or a second mode. In the first mode, the target area 10 is Lissajous scanned with the illumination light 20La. Lissajous scanning is advantageous over raster scanning in that it can quickly find a portion of interest within the target area 10. In the second mode, the target area 10a including the portion of interest within the target area 10 is scanned with the illumination light 20La. The portion of interest is a portion for which it is desired to obtain point cloud information in more detail, more accurately, or more quickly. A typical example of a portion of interest is an object present in the target area 10.

[0025] In the measurement device 100A according to the first embodiment, the processing circuitry 52 stores point cloud information generated by performing a Lissajous scan of the target region 10 in the first mode in the memory 54, and erases or overwrites at least a portion of the stored point cloud information from the memory 54 at each update interval. The processing circuitry 52 further determines, during a period corresponding to the update interval, at each determination interval shorter than the update interval, whether to switch from the first mode to the second mode based on the point cloud information stored in the memory 54. Based on the determination result, the processing circuitry 52 scans the region of interest 10a in the second mode.

[0026] The above measurement operation allows a determination of mode switching at a determination interval shorter than the update interval during a period corresponding to the update interval. Therefore, a scan in the first mode during that period is counted as one scan, and the mode can be switched midway through a single Lissajous scan of the target area 10 in the first mode, and the region of interest 10a can be scanned in the second mode. As a result, it is possible to find and scan the region of interest 10a more quickly than in a measurement operation in which a determination of mode switching is made after one Lissajous scan of the target area 10 in the first mode is completed.

[0027] The target area 10, and the light source 20, scanner 30, photodetector 40, and processing device 50 included in the measurement device 100A will be described in detail below.

[0028] <Target Area 10> The target area 10 is an area that can be illuminated with the illumination light 20La emitted from the light source 20 and whose illumination angle is changed by the scanner 30. While FIG. 1A illustrates the target area 10 as a plane for ease of explanation, the target area 10 may generally have distance variations in the depth direction. The target area 10 may include an object to be measured. The object may be, for example, a structure at a construction site or a large product manufactured in a factory. The structure may be formed from, for example, concrete members, metal members, or wood. The factory product may be, for example, an automobile, a home appliance, or a machine part. While a large object is used as the measurement object in this example, a smaller object may also be used as the measurement object depending on the application.

[0029] <Light Source 20> The light source 20 emits irradiation light 20La for irradiating the target area 10. The irradiation light 20La may be, for example, laser light with high coherence. The wavelength of the laser light may be, for example, within the near-infrared wavelength range of 700 nm or more and 2000 nm or less. Sunlight includes near-infrared light and visible light, and the amount of near-infrared light is less than the amount of visible light. Therefore, using near-infrared light as the laser light can reduce the influence of sunlight as noise. The wavelength of the laser light does not necessarily have to be within the near-infrared wavelength range. The wavelength of the laser light may be within the visible light wavelength range of 400 nm or more and 700 nm or less, or may be within the ultraviolet wavelength range.

[0030] The light source may comprise, for example, a distributed feedback (DFB) laser diode, an external cavity (EC) laser diode, or a vertical cavity surface emitting (VCSEL) laser diode, which are inexpensive, small, and capable of single-mode oscillation.

[0031] <Scanner 30> The scanner 30 changes the irradiation angle of the irradiation light 20La by changing the orientation of the mirror that reflects the irradiation light 20La in response to a control signal sent from the processing circuit 52. The control signal includes information regarding the irradiation angle.

[0032] The scanner 30 includes a mirror that reflects the illumination light 20La toward the target area 10 and a driver that drives the mirror. The illumination light 20La reaches an illumination point 12 on the target area 10 as a beam. The mirror may be, for example, a MEMS (Micro Electro Mechanical System) mirror, a galvanometer mirror, or a polygon mirror. The driver changes the orientation of the mirror in response to the control signal. As a result, the illumination angle of the illumination light 20La reflected by the mirror changes, and the position of the illumination point 12 on the target area 10 changes.

[0033] In a Lissajous scan, the scanner 30 simultaneously changes the irradiation angle of the irradiation light 20La in a first direction and a second direction that are orthogonal to each other. The first direction may be, for example, the horizontal direction, and the second direction may be, for example, the vertical direction. In the following description, the first direction is referred to as the X direction, and the second direction is referred to as the Y direction. When the target area 10 is a plane, the irradiation point 12 moves two-dimensionally on the target area 10 along the scanning path.

[0034] <Photodetector 40> Upon receiving a control signal sent from the processing circuit 52, the photodetector 40 detects the reflected light 20Lb from the target area 10 and outputs a detection signal corresponding to the intensity of the reflected light 20Lb. The control signal includes information on the detection timing and / or the output timing of the detection signal. Note that the processing circuit 52 may sample the detection signal at a predetermined timing while the photodetector 40 is constantly detecting the reflected light 20Lb. In this case, the processing circuit 52 does not need to send the above control signal, and the photodetector 40 does not need to receive the above control signal.

[0035] The photodetector 40 includes one or more photodiodes. The photodiodes output signals corresponding to the intensity of the reflected light 20Lb. The photodetector 40 may include a preamplifier that amplifies the signals.

[0036] 1B , the processing device 50 includes a processing circuit 52 and a memory 54. The processing circuit 52 includes a control circuit 52 a, a drive circuit 52 b, and a signal processing circuit 52 c. The operations performed by the control circuit 52 a, the drive circuit 52 b, and the signal processing circuit 52 c may be considered as operations performed by the processing circuit 52.

[0037] The control circuit 52a sends a control signal including information about the irradiation angle to the scanner 30 to control the scanner 30 in a plurality of modes including the first and second modes described above. The control circuit 52a determines whether to switch from the first mode to the second mode.

[0038] The control circuit 52 a controls the photodetector 40 by sending a control signal including information on the detection timing and / or output timing to the photodetector 40 .

[0039] The control circuit 52a controls the drive circuit 52b by sending a control signal including information on the intensity and emission timing of the irradiation light 20La to the drive circuit 52b. The drive circuit 52b drives the light source 20 by sending a drive signal to the light source 20. The drive signal may be, for example, a voltage signal or a current signal. It can also be said that the control circuit 52a controls the light source 20 via the drive circuit 52b. The control circuit 52a controls the signal processing circuit 52c by sending a control signal including information on signal processing to the signal processing circuit 52c.

[0040] The signal processing circuit 52c uses ToF LiDAR technology to generate and output distance information at the irradiation point 12. Alternatively, the signal processing circuit 52c may use FMCW LiDAR technology to generate distance information and / or velocity information at the irradiation point 12.

[0041] The signal processing circuit 52c sends the distance information and / or velocity information at the plurality of irradiation points 12 as point cloud information to the memory 54. The irradiation angle and distance information at the irradiation points 12 may be combined to obtain the position information of the irradiation points 12.

[0042] The memory 54 stores the point cloud information. Since the memory 54 has a finite capacity, at least a portion of the contents of the memory 54 is erased or overwritten at each update interval when the number of irradiation points 12 in the point cloud information reaches a predetermined number. The memory 54 has a space reserved in advance for storing point cloud information in which the number of irradiation points 12 has reached the predetermined number. When a Lissajous scan of the target region 10 is completed in the period corresponding to the update interval, the number of irradiation points 12 matches the predetermined number.

[0043] When erasing the contents of the memory 54, the contents may be erased all at once, or information on the oldest irradiation points 12, the number of which corresponds to the number of newly stored items, may be erased one by one. When overwriting the contents of the memory 54, information on the oldest irradiation points 12, the number of which corresponds to the number of newly stored items, may be overwritten one by one.

[0044] The memory 54 may be a storage element dedicated to storing point cloud information. The storage element may be, for example, a DRAM. Alternatively, the memory 54 may be part of a storage element provided by the processing circuitry 52 for the purpose of storing and executing programs and circuit logic. Alternatively, if the measurement device 100A includes a display device, the memory 54 may be part of a storage element provided by the display device for the purpose of displaying the point cloud information.

[0045] The signal processing circuit 52c may input the point cloud information to a display (not shown). The display displays the point cloud information. Alternatively, the signal processing circuit 52c may input the output point cloud information to another device. The other device performs a specific operation based on the point cloud information. The other device may be, for example, a vehicle or an industrial robot.

[0046] The computer programs executed by the control circuit 52a and the signal processing circuit 52c are stored in memory 54. The processing circuit 52 and memory 54 may be integrated on a single circuit board or provided on separate circuit boards. The control circuit 52a, drive circuit 52b, and signal processing circuit 52c included in the processing circuit 52 may be distributed across multiple circuits. The processing device 50, or parts thereof, may be installed in a remote location away from the other components and control the light source 20, scanner 30, and photodetector 40 via a wired or wireless communication network.

[0047] [Example of Point Cloud Information Stored in Memory 54] Next, an example of point cloud information stored in memory 54 will be described with reference to Fig. 2. Fig. 2 is a diagram schematically showing an example of point cloud information stored in memory 54. In the example shown in Fig. 2, the point cloud information is expressed in a table format. Items shown in Fig. 2 include, for example, the irradiation angle θ in the X direction of the scanner 30, Ｘ , the irradiation angle θ in the Y direction Ｙ , distance information d at the irradiation point 12, and velocity information v at the irradiation point 12. Ｘ , θ Ｙ , d, the position of the illuminated point 12 may be expressed in Cartesian or polar coordinates.

[0048] The memory 54 stores values ​​corresponding to these items for each irradiation point 12. The same suffix (1, 2, ..., n) indicates the same irradiation point 12. n indicates a predetermined number. In other words, once point cloud information for n irradiation points 12 has been stored in the memory 54, at least a portion of the contents of the memory 54 is erased or overwritten. The time required to acquire information for one irradiation point 12 is defined as t ｍ Then, the update interval I ｕ is I ｕ = t ｍ ×n.

[0049] The processing circuit 52 determines whether to switch modes by updating the update interval I ｕ In the update interval I ｕ A judgment interval I shorter than ｊ The point cloud information stored in the memory 54 is acquired at each determination interval I. ｊ The number of irradiation points 12 in the point cloud information acquired each time is not necessarily constant. When the number of determinations is small, the number of irradiation points 12 in the point cloud information also becomes small.

[0050] In the measuring apparatus 100A according to the first embodiment, the update interval is also referred to as a "first time interval," and the determination interval is also referred to as a "second time interval."

[0051] [Mode Switching from First Mode to Second Mode] Next, the mode switching from the first mode to the second mode will be described. ｕ In the period corresponding to the update interval I ｕ A judgment interval I shorter than ｊ At each time, it is determined whether to switch from the first mode to the second mode based on the point cloud information acquired from the memory 54.

[0052] The processing circuitry 52 executes, for example, a program to search for information on the portion of interest in the point cloud information. The search for the portion of interest is performed using a known method. Specifically, it is searched for whether information on the characteristic shape, distance, and speed of the portion of interest is included in the point cloud information, and if so, which portion of the target area 10 it is. A specific example of a method for searching for the portion of interest will be described in the application example below.

[0053] When the processing circuitry 52 determines that a target portion exists in the target area 10, it calculates the irradiation angle of the target area 10a including the target portion, and sends a mode switching control signal to the scanner 30.

[0054] The determination of the mode switching may be performed by a program or circuit logic. The program or circuit logic may be, for example, a part of the program or circuit logic executed by the processing circuitry 52. ​​If it is a program, it is possible to flexibly construct a search and determination algorithm for the region of interest 10a according to the type and / or characteristics of the portion of interest.

[0055] [Example of Scanning in First Mode and Second Mode] Next, an example of scanning in the first mode and the second mode will be described with reference to Fig. 3. Fig. 3 is a diagram for explaining an example of scanning in the first and second modes.

[0056] 3, in the first mode, the target area 10 is subjected to a Lissajous scan. For the Lissajous scan, the vibration frequency f Ｘ and vibration frequency f in the Y direction Ｙ When the ratio of f to f is a rational number, one period of the Lissajous scan can be defined. In this case, the update interval at which the number of irradiation points 12 reaches a predetermined number may be set to coincide with one period of the Lissajous scan. Ｘ and f Ｙ If the ratio of is an irrational number, the path of the Lissajous scan does not return to the starting point, and the period of the scan cannot be defined.

[0057] However, in the measurement apparatus 100A according to the first embodiment, f Ｘ and f Ｙ Regardless of whether the ratio between is a rational number or an irrational number, a scan in the first mode during a period corresponding to the update interval can be treated as one scan.

[0058] <Second Mode> In the second mode, the region of interest 10a including a portion of interest within the target region 10 can be scanned, for example, as shown in A to D below. The region of interest 10a may be part or all of the target region 10. Alternatively, the region of interest 10a may have a region that overlaps the target region 10 and a region that does not overlap the target region 10.

[0059] A: The scan range is narrowed and a Lissajous scan is performed on a region of interest 10a, which is part of the target region 10. The scan parameters in this case are the range of irradiation angles in the X and / or Y directions. In this way, the region of interest 10a, which is the scan range in the second mode, is narrower than the target region 10, which is the scan range in the first mode. The narrower region of interest 10a can be measured more quickly and in more detail.

[0060] B: The center of the scan range is changed, and a Lissajous scan is performed on the region of interest 10a that partially overlaps the target region 10. The scan parameter in this case is the center of the irradiation angle range. In this way, the center of the scan range in the second mode is different from the center of the scan range in the first mode. On the other hand, the extent of the region of interest 10a, which is the scan range in the second mode, may be the same as the extent of the target region 10, which is the scan range in the first mode. Even if the region of interest moves, it is possible to measure so as to track the region of interest 10a, which includes the region of interest and its surrounding area.

[0061] C: The target region 10 is raster scanned as the region of interest 10a. The scan parameter in this case is the scan method. Point cloud information in which multiple irradiation points 12 are arranged in a grid pattern on the region of interest 10a is obtained, making post-processing of the point cloud information easier.

[0062] D: The target region 10 is subjected to a Lissajous scan as a region of interest 10a, with the spatial density of the irradiation points 12 being varied. The scan parameters in this case are the measurement period and the vibration frequency. The spatial density can be increased by shortening the measurement period or slowing the vibration frequency. In this way, the spatial density of the irradiation points 12 in the second mode is higher than the spatial density of the irradiation points in the first mode. In this case, a larger capacity of the memory 54 for storing point cloud information may be temporarily secured. Although this increases the measurement time and the measurement load, the region of interest 10a including the target portion can be obtained more quickly and in more detail.

[0063] The scanning parameters in the second mode may be combined with each other, except for scanning methods such as Lissajous scanning and raster scanning.

[0064] [Example 1 of Measurement Operation] Next, Example 1 of measurement operation executed by the processing circuitry 52 will be described with reference to Fig. 4. Fig. 4 is a flowchart that schematically shows Example 1 of measurement operation executed by the processing circuitry 52. ​​The processing circuitry 52 executes the operations of steps S101 to S111 shown in Fig. 4.

[0065] <Step S101> The control circuit 52a included in the processing circuit 52 drives the scanner 30 in a first mode for performing a Lissajous scan of the target area 10. Specifically, the control circuit 52a sends control signals to the scanner 30 to set the irradiation angles in the X and Y directions so that the target area 10 is irradiated with the irradiation light 20La, thereby changing the irradiation angle for each irradiation point 12. By performing the Lissajous scan, the irradiation points 12 follow dispersed paths on the target area 10.

[0066] <Step S102> The signal processing circuit 52c included in the processing circuit 52 generates distance information and / or velocity information at the irradiation point 12, which constitutes point cloud information in the target area 10, based on the detection signal output by the photodetector 40 after detecting the reflected light 20Lb. The information at the irradiation point 12 is sequentially stored in the memory 54 in a format such as that shown in FIG. 2, for example.

[0067] <Step S103> The control circuit 52a included in the processing circuit 52 determines whether point cloud information in which the number of irradiation points 12 has reached a predetermined number has been stored in the memory 54. Specifically, the control circuit 52a obtains the number of irradiation points 12 in the point cloud information stored in the memory 54, and determines whether the number has reached a predetermined number. The predetermined number may be, for example, the number of point cloud information stored until the memory 54 is full.

[0068] If the determination is Yes, the control circuit 52a executes the operation of step S104. If the determination is No, the control circuit 52a executes the operation of step S105.

[0069] <Step S104> The control circuit 52a included in the processing circuit 52 causes the memory 54 to erase all point cloud information.

[0070] <Step S105> The control circuit 52a included in the processing circuit 52 stores information at the irradiation point 12 that constitutes point cloud information in the target region 10 in the memory 54.

[0071] <Step S106> The control circuit 52a included in the processing circuit 52 determines whether the time has reached the determination interval for the first time since the start of scanning in the first mode, or whether the time has reached the determination interval again since the previous determination interval. ｍ is constant and the judgment interval I ｊ The number of judgment points N is the number of irradiation points 12 in the point cloud information for each ｊ If the determination interval I is constant, the determination may be made as follows: ｊ Instead, the number of irradiation points 12 measured since the previous determination in the point cloud information stored in the memory 54 is set to the determination number N ｊ =I ｊ ÷t ｍ It is determined whether the determination interval I ｊ The minimum value that can be taken as t ｍ That is, a determination is made every time information at one irradiation point 12 is accumulated. ｊ The maximum value that can be taken as I ｕ -t ｍThat is, the determination is made when the number of irradiation points 12 in the point cloud information is the maximum number that is less than a predetermined number.

[0072] Shortening the judgment interval increases the frequency of mode switching judgments, thereby increasing the probability of quickly finding the target part. However, if the judgment interval is too short, the calculation time required to find the target part may be longer than the judgment interval. Therefore, the judgment interval is adjusted appropriately depending on the calculation time.

[0073] If the determination interval is equal to or greater than the oscillation period in the X direction and equal to or greater than the oscillation period in the Y direction of the Lissajous scan, the portion of interest can be found efficiently. This is because if the determination interval is equal to or greater than this oscillation period, the target area 10 is scanned from end to end in both the X and Y directions, increasing the probability of finding the portion of interest.

[0074] If the determination is Yes, the control circuit 52a executes the operation of step S107. If the determination is No, the control circuit 52a executes the operation of step S102 again. When the operation of step S102 is executed again, the signal processing circuit 52c generates information at another irradiation point 12.

[0075] <Step S107> The control circuit 52a included in the processing circuit 52 acquires the point cloud information from the memory 54.

[0076] <Step S108> The control circuit 52a included in the processing circuit 52 determines whether to switch from the first mode to the second mode based on the acquired point cloud information. This determination is made by checking whether the features of the target portion can be obtained from information at one or more irradiation points 12 included in the point cloud information.

[0077] For example, if the shape of the portion of interest obtained from information at one or more irradiation points 12 included in the point cloud information resembles the shape of an object previously stored in memory 54, the portion where the one or more irradiation points 12 hit is determined to be the portion of interest.

[0078] Alternatively, before performing the first example of the measurement operation, point cloud information generated by performing a Lissajous scan of the target area 10 in a steady state is stored in memory 54. If information at a certain irradiation point 12 included in the acquired point cloud information differs from information at the same or a nearby irradiation point 12 included in the point cloud information in the steady state, the portion where the certain irradiation point 12 falls is determined to be the portion of interest.

[0079] <Step S109> The control circuit 52a included in the processing circuit 52 drives the scanner 30 in the second mode to scan the region of interest 10a including the target portion. Specifically, the control circuit 52a sends a control signal to the scanner 30 to set the irradiation angles in the X and Y directions so that the region of interest 10a is irradiated with the irradiation light 20La, thereby changing the irradiation angle for each irradiation point 12.

[0080] As shown in FIG. 3 , the first and second modes use different scan parameters. The scan parameters for the second mode, which scans the region of interest 10a, are determined based on information about the irradiation angle of the region of interest. The control circuit 52a, for example, acquires information about the range of irradiation angles at which the region of interest 10a can be irradiated, and drives the scanner 30 within a range limited to the region of interest 10a. When the region of interest 10a is narrower than the target region 10, as in the top example of the second mode shown in FIG. 3 , if the oscillation period is the same in the first and second modes, point cloud information with a higher spatial density of irradiation points 12 can be acquired. This allows for detailed examination of the region of interest 10a.

[0081] <Step S110> The control circuit 52a included in the processing circuit 52 stores the point cloud information in the region of interest 10a in the memory 54. Specifically, the control circuit 52a executes the operation of storing information at the irradiation points 12 that constitutes the point cloud information in the region of interest 10a in the memory 54 for all irradiation points 12 included in the region of interest 10a.

[0082] <Step S111> The control circuit 52a included in the processing circuitry 52 outputs the point cloud information for the region of interest 10a stored in the memory 54. The output destination of the point cloud information for the region of interest 10a may be a display device (not shown) or a host system of the measurement device 100A.

[0083] As explained with reference to Figure 4, in example 1 of the measurement operation, when point cloud information in which the number of irradiation points 12 reaches a predetermined number is stored in memory 54, all point cloud information is erased from memory 54, and a mode switching decision is made based on the point cloud information that has been stored again.

[0084] Next, an example of the relationship between the update interval and the judgment interval in Example 1 of the measurement operation will be described with reference to FIG. 5 . FIG. 5 is a diagram for explaining an example of the relationship between the update interval and the judgment interval in Example 1 of the measurement operation. In the example shown in FIG. 5 , time passes from top to bottom. The double-headed arrows in FIG. 5 represent the update interval and the judgment interval. "N" in FIG. 5 represents the number of judgments. The table shown in FIG. 5 shows how multiple irradiation points 12 in the point cloud information used at each judgment are distributed in the target area 10. Each irradiation point 12 is plotted as a black circle at an irradiation angle in the X direction and the Y direction. The open arrows in FIG. 5 represent the correspondence between the number of judgments and the point cloud information.

[0085] In the example shown in FIG. 5, the target area 10 has a vibration frequency f Ｘ = 8 Hz and vibration frequency in the Y direction f Ｙ In the example shown in FIG. Ｘ and f ＹSince the ratio of x to y is a rational number, one cycle of the Lissajous scan can be defined, and the scan path returns to the starting point one second after the scan begins. During one second after the scan begins, the scan path oscillates eight times in the X direction and nine times in the Y direction. Furthermore, in the example shown in FIG. 5 , 900 point clouds are acquired per second, and the measurement period is 1 / 900 seconds. The number of irradiation points 12 in the point cloud information stored in the memory 54 is assumed to be 900. That is, the predetermined number is 900, and the update interval is one second. If the update interval of the memory 54 is the same as one cycle of the Lissajous scan, the numbers of the irradiation points 12 in the point cloud information stored in the memory 54, such as the suffix shown in FIG. 2, will always be the same as the order in which the irradiation points 12 are irradiated in one cycle of the Lissajous scan. Therefore, the point cloud information stored in the memory 54 can be easily managed.

[0086] After the point cloud information in which the number of irradiation points 12 reaches a predetermined number is stored in memory 54, the contents of memory 54 are erased and information on newly measured irradiation points 12 is stored. If the number of determinations is i, then from the eighth determination onwards, the number of irradiation points 12 in the point cloud information used for determination will be the same as in the (i mod 8)th determination, where mod represents the remainder.

[0087] 5, the determination interval is equal to the oscillation period of the Lissajous scan in the X direction. Since the oscillation period in the Y direction is shorter than the oscillation period in the X direction, the path of the Lissajous scan oscillates at least one period in the Y direction for every one period in the X direction.

[0088] From the above, in the example shown in FIG. 5, the number of point clouds obtained in the period corresponding to the determination interval is 900 / 8 = 132 or 133. Because the number of point clouds is a discrete value, the number varies with each determination. The determination interval is 1 / 8 = 0.125 seconds. Therefore, by the time the contents of memory 54 are erased once, eight determinations are performed based on the point cloud information accumulated up to that point. In this way, in measurement operation example 1, the determination interval can be made shorter than the update interval.

[0089] [Example 2 of Measurement Operation] Next, Example 2 of the measurement operation performed by the processing circuitry 52 will be described with reference to Fig. 6. Fig. 6 is a flowchart that schematically shows Example 2 of the measurement operation performed by the processing circuitry 52. ​​The processing circuitry 52 performs the operations of steps S201 to S211 shown in Fig. 6. The operations of steps S201 to S203 and S205 to S211 shown in Fig. 6 are the same as the operations of steps S101 to S103 and S105 to S111 shown in Fig. 4, respectively.

[0090] <Step S204> The control circuit 52a included in the processing circuit 52 causes the memory 54 to delete from the point cloud information the information at the irradiation points 12 for which distance information and / or velocity information was generated in step S202, for each of the irradiation points 12. For example, if the number of irradiation points 12 for which distance information and / or velocity information was generated in step S202 is one, the information at one irradiation point 12 is deleted from the point cloud information.

[0091] If the oldest information is deleted from the point cloud information stored in the memory 54, the oldest information is rewritten, so that mode switching can always be determined based on the most recent point cloud information.

[0092] As explained with reference to Figure 6, in example 2 of the measurement operation, once point cloud information in which the number of irradiation points 12 has reached a predetermined number is stored in memory 54, a mode switching decision is thereafter always made based on the point cloud information in which the number of irradiation points 12 has reached the predetermined number.

[0093] Next, an example of the relationship between the update interval and the determination interval in measurement operation example 2 will be described with reference to Fig. 7. Fig. 7 is a diagram for explaining an example of the relationship between the update interval and the determination interval in measurement operation example 2. The double arrow, "N", and table shown in Fig. 7 are as described with reference to Fig. 5.

[0094] The point cloud information used for the determination when N≦8 in the example shown in FIG. 7 is the same as the point cloud information used for the determination when N≦8 in the example shown in FIG. 5. The number of irradiation points 12 in the point cloud information used for the determination when N≧9 in the example shown in FIG. 7 is a predetermined number, different from the number of irradiation points 12 in the point cloud information used for the determination when N≧9 in the example shown in FIG. 5. However, the point cloud information is rewritten from the old information. The point cloud information when N=16 has been completely rewritten compared to the point cloud information when N=8. In the table shown in FIG. 7, larger black circles represent irradiation points 12 whose information has been rewritten.

[0095] If the update interval is defined as the interval at which all of the point cloud information is rewritten, then the determination interval is 0.125 seconds and the update interval is 1 second, as in the example shown in Fig. 5. Until all of the point cloud information in memory 54 is rewritten, determination is performed eight times based on the point cloud information stored in memory 54. Therefore, even in measurement operation example 2, the determination interval can be made shorter than the update interval.

[0096] As described above, the measurement apparatus 100A according to the first embodiment can determine whether to switch modes at determination intervals that are shorter than the update intervals during a period corresponding to the update interval. Therefore, the mode can be switched midway through a single Lissajous scan of the target region 10 in the first mode, and the region of interest 10a can be scanned in the second mode. As a result, the region of interest 10a, which includes the portion of interest within the target region 10, can be found and scanned more quickly.

[0097] Second Embodiment In the following, an example of the configuration of a measurement device according to a second embodiment of the present disclosure will be described, followed by an example of a measurement operation.

[0098] [Measurement Apparatus] First, an example configuration of a measurement apparatus according to embodiment 2 of the present disclosure will be described with reference to FIGS. 8A and 8B . FIG. 8A is a block diagram schematically illustrating the configuration of a measurement apparatus according to exemplary embodiment 2 of the present disclosure. The measurement apparatus 100B shown in FIG. 8A differs from the measurement apparatus 100A shown in FIG. 1A in that the measurement apparatus 100B further includes a display device 60 and an input device 70. However, the display device 60 and the input device 70 do not need to be components of the measurement apparatus 100B, and may be external components of the measurement apparatus 100B. FIG. 8B is a diagram schematically illustrating an example configuration of a processing device 50 included in the measurement apparatus 100B shown in FIG. 8A.

[0099] Unlike the measuring device 100A according to embodiment 1, the measuring device 100B according to embodiment 2 is configured such that the user determines whether to switch modes. The user determines whether to switch from the first mode to the second mode based on the point cloud information displayed on the display device 60. When switching from the first mode to the second mode, the user inputs information for switching modes into the input device 70.

[0100] In a highly accurate scan, the measurement time at one irradiation point 12 may be long, and the update interval may be several minutes. In this case, even if the user decides to switch modes while performing a Lissajous scan of the target region 10, the time required for the user to make the decision is sufficiently short compared to the update interval. If the point cloud information displayed on the display device 60 includes information about the portion of interest as a result of the user's decision to switch modes, the user can visually confirm whether or not the portion of interest is actually present in the target region 10.

[0101] As will be described in detail later, in the measurement device 100B according to the second embodiment, the processing circuitry 52 stores point cloud information generated by scanning the target region 10 in the first mode in the memory 54, and overwrites or erases at least a portion of the stored point cloud information from the memory 54 at each update interval. The processing circuitry 52 further causes the display device 60 to acquire the point cloud information from the memory 54 and display the point cloud information at each display interval shorter than the update interval during a period corresponding to the update interval. The processing circuitry 52 further causes the input device 70 to be ready to receive input from the user regarding whether to switch from the first mode to the second mode at each input interval shorter than the update interval during a period corresponding to the update interval. The processing circuitry 52 scans the region of interest 10a in the second mode based on the input result.

[0102] The above measurement operation allows mode switching determination to be performed for each display interval and input interval that is shorter than the update interval during a period corresponding to the update interval. Therefore, it is possible to switch modes during one Lissajous scan of the target area 10 in the first mode and scan the area of ​​interest 10a in the second mode. As a result, it is possible to find and scan the area of ​​interest 10a more quickly.

[0103] The display device 60 and the input device 70 will be described in detail below.

[0104] <Display Device 60> The display device 60 receives a control signal sent from the processing circuit 52 and displays the point cloud information acquired from the memory 54 to the user.

[0105] <Input Device 70> Upon receiving a mode switching instruction from a user, the input device 70 sends a mode switching input signal to the processing circuit 52, as shown in Fig. 8B. The processing circuit 52 receives the input signal and sends a mode switching control signal to the scanner 30.

[0106] The input device 70 may be, for example, a mouse and a keyboard, or may be a GUI (Graphical User Interface) displayed on the display device 60.

[0107] The display interval I for updating the point cloud information displayed on the display device 60 ｄ is the update interval I ｕ The input interval I is the time interval during which the input device 70 receives an input from the user and sends an input signal to the processing device 50. ｉ The same applies to the update interval I ｕ and display interval I ｄ The update interval I ｕ and display interval I ｄ may not be synchronized in time.

[0108] In the measurement device 100B according to the second embodiment, the update interval is also referred to as the "first time interval," the display interval is also referred to as the "second time interval," and the input interval is also referred to as the "third time interval."

[0109] [Measurement Operation Example 3] Next, with reference to Fig. 9, a measurement operation example 3 of the measuring device 100B executed by the processing circuitry 52 will be described. Fig. 9 is a flowchart that schematically illustrates the measurement operation example 3 executed by the processing circuitry 52. ​​The processing circuitry 52 executes the operations of steps S301 to S312 shown in Fig. 9. The operations of steps S301 to S305 and S310 to S312 shown in Fig. 6 are the same as the operations of S101 to S105 and S109 to S111 shown in Fig. 4, respectively. Note that the processing circuitry 52 may execute the operation of step S204 shown in Fig. 6 instead of the operation of S304.

[0110] <Step S306> The control circuit 52a included in the processing circuit 52 detects the display interval I for the first time after the start of scanning in the first mode. ｄ has been reached or the time has elapsed since the last display interval I ｄ When the display interval reaches I ｄ The control circuit 52a further determines whether the input interval I has been reached for the first time since the start of scanning in the first mode. ｉ has been reached or the time has passed since the last input interval I ｉ When the input interval I ｉ It is determined whether the display interval I ｄ and input interval I ｉIf the display interval I is the same, the above two determinations can be made at the same time. However, the above two determinations may be made independently at different times. ｄ and input interval I ｉ Regarding the determination interval I in step S106 shown in FIG. ｊ is the same as:

[0111] <Step S307> The control circuit 52a included in the processing circuit 52 causes the display device 60 to display the point cloud information stored in the memory 54.

[0112] <Step S308> The control circuit 52a included in the processing circuitry 52 causes the input device 70 to be ready to receive input from the user, and to receive the input from the user. The input from the user may be, for example, a mode switching instruction and information regarding scan parameters in the second mode.

[0113] The timing at which the display device 60 displays the point cloud information and the timing at which the input device 70 becomes ready to receive input from the user may be the same or different.

[0114] <Step S309> The control circuit 52a included in the processing circuit 52 receives an input signal from the input device 70 and determines whether or not to switch from the first mode to the second mode.

[0115] As described above, the measurement device 100B according to embodiment 2 can also determine whether to switch modes at display intervals and input intervals that are shorter than the update interval, in a period corresponding to the update interval, similar to the measurement device 100A according to embodiment 1. Therefore, it is possible to switch modes midway through a single Lissajous scan of the target area 10 in the first mode, and scan the region of interest 10a in the second mode. As a result, it is possible to more quickly find and scan the region of interest 10a that includes the portion of interest within the target area 10.

[0116] 10A to 10C, an example of the measurement device 100A according to the first embodiment will be described together with a comparative example. In the example, the target area 10 is subjected to a Lissajous scan, and in the comparative example, the target area 10 is subjected to a raster scan.

[0117] 10A is a diagram showing the distribution of the irradiation points 12 in a comparative example. In the example shown in FIG. 10A, the distribution of the irradiation points 12 for one period in the raster scan is Ｘ , θ Ｙ The predetermined number of points was 900, the update interval was 1 second, and the irradiation angle range was ±10° in both the X and Y directions. In the raster scan, the irradiation point 12 moves from a start point on the first row at the top left to the first row at the top right, then to the second row at the top right, following a path that reaches the second row at the top left, and finally reaches an end point on the 30th row at the bottom left.

[0118] 10B is a diagram showing the distribution of the irradiation points 12 in the example. In the example shown in FIG. 10B, the distribution of the irradiation points 12 for one period in the Lissajous scan is Ｘ , θ Ｙ The predetermined number, update interval, and irradiation angle range in the example are the same as the predetermined number, update interval, and irradiation angle range in the comparative example, respectively. The vibration frequency of the Lissajous scan was 8 Hz in the X direction and 9 Hz in the Y direction. In the Lissajous scan, the irradiation point 12 moves from the starting point at the center of the top along the Lissajous pattern and finally reaches the vicinity of the starting point.

[0119] In the following, the range of the irradiation angle of the target area 10 is divided at equal angular intervals into sub-areas, and the timing at which the irradiation point 12 will hit each sub-area is estimated. Specifically, this is as follows. The angular intervals in both the X and Y directions are set to 2°, and the number of sub-areas is 100. If the irradiation point 12 hits somewhere within a sub-area, that is, if the irradiation angle of the irradiation point 12 is within the angular range of the sub-area, it becomes possible to determine whether to switch modes in that sub-area. This state can also be said to be the sub-area being covered.

[0120] As the amount of point cloud information stored in memory 54 during one scanning cycle increases, the coverage rate, which is the ratio of the number of covered subregions to the number of all subregions, increases. The tendency of this increase in coverage rate was compared between the comparative example and the example.

[0121] 10C is a graph showing the relationship between the number of irradiation points 12 in the point cloud information stored in memory 54 and the coverage ratio for the comparative example and the example. As shown in FIG. 10C, the coverage ratio for the example is higher than that for the comparative example, except near the start and end of one cycle of scanning. That is, the example can cover more sub-regions with fewer irradiation points 12 than the comparative example. This is because the target region 10 is scanned in a dispersed manner in the Lissajous scan.

[0122] Therefore, there is a high possibility that the portion of interest can be found quickly by performing a Lissajous scan of the target area 10. For this reason, if the mode is switched before the number of irradiation points 12 in the point cloud information reaches a predetermined number, there is a high probability that the area of ​​interest 10a can be measured more quickly and in detail.

[0123] (Application Example) Hereinafter, with reference to FIGS. 11A and 11B, an example in which example 1 of the measurement operation performed by the processing circuit 52 is applied to monitoring and security applications will be described.

[0124] Before performing measurement operation example 1, processing circuitry 52 stores point cloud information generated by performing a Lissajous scan of target area 10 in a steady state in memory 54. If the scan parameters used to acquire the point cloud information in the steady state are the same as the scan parameters used in the first mode, it becomes easier to check the irradiation angle.

[0125] 11A is a flowchart showing an example of the operation of step S108 executed by the processing circuitry 52 in measurement operation example 1. In step S108 shown in FIG. 4, the processing circuitry 52 executes the operations of steps S108a and S108b shown in FIG. 11A.

[0126] <Step S108a> The control circuit 52a included in the processing circuit 52 acquires the steady-state point cloud information stored in the memory 54 and refers to the steady-state point cloud information.

[0127] <Step S108b> The control circuit 52a included in the processing circuit 52 determines whether the point cloud information acquired in step S107 shown in Fig. 4 differs from the steady-state point cloud information. The control circuit 52a determines whether the absolute value of the difference in distance and / or speed at the same or nearby irradiation points 12 in these two pieces of point cloud information is equal to or greater than a predetermined threshold value.

[0128] If the determination is Yes, the control circuit 52a executes the operation of step S109 shown in Fig. 4. If the determination is No, the control circuit 52a executes the operation of step S102 shown in Fig. 4.

[0129] Fig. 11B is a diagram illustrating an example of an operation for determining an area of ​​interest 10a by performing a Lissajous scan of the target area 10. In Fig. 11B, a person is shown in the lower right corner as the area of ​​interest. The black circles in Fig. 11B represent irradiation points 12 that do not fall on the area of ​​interest. The white circles in Fig. 11B represent irradiation points 12 that fall on the area of ​​interest.

[0130] In the example shown in FIG. 11B, similarly to the example shown in FIG. 5, the target region 10 is f Ｘ = 8 Hz, f in the Y direction Ｙ = 9 Hz. The determination interval is the same as the vibration period in the X direction. That is, the scanning path shown in Fig. 11B corresponds to the scanning path during one determination interval.

[0131] 11B , when an irradiation point 12 hits a target portion that does not exist in the steady state midway through the scan path, the information at the irradiation point 12 included in the acquired point cloud information differs from the information at the same or a nearby irradiation point 12 included in the point cloud information in the steady state. In the example shown in FIG. 11B , an abnormal state different from the steady state was discovered in the first determination.

[0132] At this time, the control circuit 52a calculates the irradiation angle of the target area 10a based on the irradiation angles of the multiple irradiation points 12 that hit the target area, and sends a mode switching control signal to the scanner 30. In the example shown in FIG. Ｘ ≦8° and −10°≦θ Ｙ Since an abnormal state was found within the range of 4°≦θ Ｘ ≦10°, −12°≦θ Ｙ The range of the irradiation angle of the region of interest 10a is set to be ≦−6°. In the second mode, more detailed point cloud information is acquired within this irradiation angle range.

[0133] In this way, during a period corresponding to the update interval, mode switching can be determined at a determination interval shorter than the update interval, and the region of interest 10a including the portion of interest can be measured more quickly and in more detail. Therefore, in surveillance and security applications, abnormal conditions can be quickly discovered and analyzed.

[0134] [Additional Notes] The above description of the embodiments discloses the following techniques.

[0135] [Technology 1] A measurement device 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 memory; and a processing circuit, wherein the processing circuit: drives the scanner in a first mode that performs a Lissajous scan of the target area, thereby illuminating the target area with the illumination light; generates point cloud information based on the detection signal; stores the point cloud information in the memory; and erases or overwrites at least a portion of the stored point cloud information at first time intervals; and determines, at second time intervals that are shorter than the first time intervals, based on the point cloud information stored in the memory, whether to switch from the first mode to a second mode having scan parameters different from those of the first mode; and drives the scanner in the second mode based on the determination result.

[0136] This measurement device can more quickly find and scan a region of interest that includes a portion of interest within a target region.

[0137] [Technology 2] The measurement device according to Technology 1, wherein the processing circuit determines whether to switch from the first mode to the second mode based on a program.

[0138] This measurement device allows for flexible construction of algorithms for searching and determining regions of interest according to the type and / or characteristics of the region of interest.

[0139] 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 memory; and a processing circuit, wherein the processing circuit: drives the scanner in a first mode that performs a Lissajous scan of the target area, thereby illuminating the target area with the illumination light; generates point cloud information based on the detection signal; stores the point cloud information in the memory, and erases or overwrites at least a portion of the stored point cloud information at first time intervals; causes a display device to retrieve the point cloud information from the memory and display the point cloud information at second time intervals that are shorter than the first time intervals; causes an input device to be ready to receive input from a user regarding whether to switch from the first mode to a second mode having scan parameters different from those of the first mode at third time intervals that are shorter than the first time intervals; and drives the scanner in the second mode based on the input result of the input device.

[0140] This measurement device can more quickly find and scan a region of interest that includes a portion of interest within a target region.

[0141] [Technology 4] The measurement device according to any one of Technologies 1 to 3, wherein the first time interval is equal to one period of the Lissajous scan.

[0142] This measuring device makes it easy to manage the point cloud information stored in the memory.

[0143] [Technology 5] The measurement device according to any one of Technologies 1 to 3, wherein the second time interval is equal to or greater than the oscillation period of the Lissajous scan in a first direction and equal to or greater than the oscillation period of the Lissajous scan in a second direction different from the first direction.

[0144] This measurement device increases the probability of finding the area of ​​interest.

[0145] [Technology 6] The measurement device according to any one of Technologies 1 to 3, wherein a scan range in the second mode is narrower than a scan range in the first mode.

[0146] This measurement device allows for detailed examination of an area of ​​interest.

[0147] [Technology 7] The measurement device according to any one of Technologies 1 to 3, wherein the center of the scan range in the second mode is different from the center of the scan range in the first mode.

[0148] With this measuring device, even when the target portion moves, it is possible to perform measurements so as to track the target region including the target portion and its surrounding area.

[0149] [Technology 8] The measurement device according to any one of Technologies 1 to 3, wherein the scan in the second mode is a raster scan.

[0150] This measurement device makes it easy to post-process point cloud information.

[0151] [Technology 9] The measurement device according to any one of Technologies 1 to 3, wherein a spatial density of the irradiation points in the second mode is higher than a spatial density of the irradiation points in the first mode.

[0152] This measuring device can obtain the region of interest containing the part of interest more quickly and in detail.

[0153] [Technology 10] The measurement device according to any one of Techniques 1 to 3, wherein the scan range in the second mode corresponds to a region of interest determined based on the point cloud information stored in the memory.

[0154] This measuring device can scan a region of interest based on point cloud information stored in memory.

[0155] The measurement device of the present disclosure can be used for applications such as measuring the shape of structures, and surveillance and security.

[0156] REFERENCE SIGNS LIST 10 Object 12 Irradiation point 20 Light source 20La Irradiation light 20Lb Reflected light 30 Scanner 40 Photodetector 50 Processing device 52 Processing circuit 52a Control circuit 52b Drive circuit 52c Signal processing circuit 54 Memory 60 Display device 70 Input device 100A, 100B Measuring device

Claims

1. A measurement device 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 memory; and a processing circuit, wherein the processing circuit: drives the scanner in a first mode that performs a Lissajous scan of the target area, illuminating the target area with the illumination light; generates point cloud information based on the detection signal; stores the point cloud information in the memory; erases or overwrites at least a portion of the stored point cloud information at first time intervals; determines at second time intervals that are shorter than the first time intervals, based on the point cloud information stored in the memory, whether to switch from the first mode to a second mode having scan parameters different from those of the first mode; and drives the scanner in the second mode based on the determination result.

2. The measurement device according to claim 1, wherein the processing circuit determines whether to switch from the first mode to the second mode based on a program.

3. A measurement device 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 memory; and a processing circuit, wherein the processing circuit: drives the scanner in a first mode that performs a Lissajous scan of the target area, illuminating the target area with the illumination light; generates point cloud information based on the detection signal; stores the point cloud information in the memory and erases or overwrites at least a portion of the stored point cloud information at first time intervals; causes a display device to retrieve the point cloud information from the memory and display the point cloud information at second time intervals that are shorter than the first time intervals; causes an input device to be ready to receive input from a user regarding whether to switch from the first mode to a second mode having scan parameters different from those of the first mode at third time intervals that are shorter than the first time intervals; and drives the scanner in the second mode based on the input result of the input device.

4. The measurement device according to any one of claims 1 to 3, wherein the first time interval is equal to one period of the Lissajous scan.

5. A measurement device as described in any one of claims 1 to 3, wherein the second time interval is equal to or greater than the oscillation period of the Lissajous scan in a first direction and equal to or greater than the oscillation period of the Lissajous scan in a second direction different from the first direction.

6. The measurement device according to any one of claims 1 to 3, wherein the scanning range in the second mode is narrower than the scanning range in the first mode.

7. A measurement device according to any one of claims 1 to 3, wherein the center of the scan range in the second mode is different from the center of the scan range in the first mode.

8. The measurement device according to any one of claims 1 to 3, wherein the scan in the second mode is a raster scan.

9. A measurement device according to any one of claims 1 to 3, wherein the spatial density of the irradiation points in the second mode is higher than the spatial density of the irradiation points in the first mode.

10. A measurement device according to any one of claims 1 to 3, wherein the scanning range in the second mode corresponds to a region of interest determined based on the point cloud information stored in the memory.

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