Measurement device and method

Abstract

Provided are a measurement device and method which are capable of remotely measuring an object with high accuracy. The measurement device, which measures the distance to or the shape of an object by scanning the object with light, comprises a focus adjustment unit for adjusting the focus of the light, and a processor. The processor controls the focus adjustment unit to focus the light on the object when scanning in a sub-scanning direction.

Description

Measuring device and method

[0001] The present invention relates to a measurement device and method, and more particularly to a measurement device and method for scanning light on an object to measure the distance to or the shape of the object.

[0002] There are known techniques for measuring the distance to an object, its shape, etc. by scanning light over the object. In particular, LiDAR (Light Detection and Ranging or Laser Imaging Detection and Ranging) is known as a technique for irradiating an object with laser light while scanning it, and measuring the distance to the object, its shape, etc. based on the reflected light (see, for example, Patent Document 1, etc.).

[0003] Patent Publication No. 2021-1787

[0004] In recent years, LIDAR technology has made great advances, and for example, vehicle-mounted LIDAR systems can now instantly measure distances up to approximately 200 meters. However, there have been issues with accuracy.

[0005] An object of one embodiment of the technique of the present disclosure is to provide a measurement device and method that can remotely measure an object with high accuracy.

[0006] (1) A measuring device that scans light onto an object to measure the distance to or shape of the object, comprising a focus adjustment unit that adjusts the focus of the light, and a processor, wherein the processor controls the focus adjustment unit to focus the light on the object during scanning in the sub-scanning direction.

[0007] (2) The measurement device according to (1), further comprising a moving body that displaces the measurement position, the moving body moving in a direction intersecting the sub-scanning direction.

[0008] (3) The measurement device according to (1) or (2), wherein the scanning speed of the light in the main scanning direction is faster than the scanning speed in the sub-scanning direction.

[0009] (4) The measurement device according to (2), wherein the scanning speed in the sub-scanning direction is faster than the moving speed of the moving body during measurement.

[0010] (5) The measurement device according to any one of (1) to (4), wherein the processor acquires design data of the object and controls the focus adjustment unit based on the design data.

[0011] (6) The measurement device according to any one of (1) to (4), wherein the processor controls the focus adjustment unit based on the measurement results of the main scan performed earlier.

[0012] (7) The measurement device according to any one of (1) to (4), further comprising a distance measurement unit, wherein the processor controls the focus adjustment unit based on the distance measurement result of the distance measurement unit.

[0013] (8) The measurement device according to any one of (1) to (7), wherein the light emitting unit rotates around an axis intersecting the sub-scanning direction to perform scanning in the sub-scanning direction.

[0014] (9) A measurement device described in any one of (1) to (7), in which light from a light source is scanned in the main scanning direction by a polygon mirror, a galvanometer mirror, or a MEMS mirror, and scanning in the sub-scanning direction is performed by rotating the polygon mirror, the galvanometer mirror, or the MEMS mirror around an axis intersecting the sub-scanning direction.

[0015] (10) The measurement device according to any one of (1) to (9), which scans with light whose frequency is periodically modulated.

[0016] (11) The measurement device according to any one of (1) to (10), wherein the object is a tunnel structure and the sub-scanning direction is the circumferential direction of the tunnel structure.

[0017] (12) A measurement device described in any one of (1) to (11), wherein the processor acquires information on measurement positions and generates three-dimensional shape data of the object based on information on the measurement results for each measurement position.

[0018] (13) The measuring device according to (12), in which, when measuring by moving along a preset route, the amount of movement of the moving body and the amount of deviation from the route are measured to obtain information on the measurement position.

[0019] (14) The measurement device according to (12), which acquires information on the measurement position using self-position estimation by SLAM.

[0020] (15) A measurement method for measuring the distance to or shape of an object by scanning light on the object, in which the light is focused on the object during scanning in the sub-scanning direction.

[0021] According to the present invention, an object can be remotely measured with high accuracy.

[0022] FIG. 1 shows an example of the configuration of a three-dimensional measuring device. FIG. 1 shows an example of the configuration of a three-dimensional measuring device. FIG. 1 shows an example of the configuration of a measurement unit composed of an FMCW lidar. Conceptual diagram of scanning by a scanning unit. FIG. 1 shows a method of injecting measurement light into a polygon mirror. FIG. 1 shows an example of the hardware configuration of a control unit. Block diagram of main functions of the control unit regarding measurement control. Conceptual diagram of focusing control. Conceptual diagram of focusing control. Conceptual diagram of measurement. FIG. 1 explains the change in separation distance during sub-scanning. FIG. 1 shows another example of change in distance to a wall surface during sub-scanning. Conceptual diagram of measurement results. FIG. 1 shows another example of focusing in the sub-scanning direction. FIG. 1 shows another example of focusing in the sub-scanning direction. FIG. 1 shows a schematic configuration of a three-dimensional measuring device. Flowchart showing an example of a measurement procedure.

[0023] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0024] Here, the present invention will be described as being applied to a device (three-dimensional measurement device) that uses a lidar to three-dimensionally measure the shape of a concrete structure, particularly for the purpose of diagnosing deterioration based on lift.

[0025] Here, "floating concrete" refers to the condition in which the concrete near the surface is floating. Floating concrete refers to a state in which the concrete near the surface is losing its integrity with the concrete inside due to continuous cracks inside the concrete, etc.

[0026] Floating detection is performed using the following procedure. First, a height image is generated from the results of 3D measurement of the object. The height image is generated by calculating the height as the difference between the 3D measurement results and a reference plane. The reference plane may be based on past measurement results, design data for the object (design drawings, etc.), or a curved surface estimated from the 3D measurement results. The generated height image is analyzed to extract the floating area. Specifically, the height image is binarized, and the contour is extracted from the binarized image to extract the floating area. The area, height (average, maximum, etc.), volume, etc. of the extracted floating area are calculated.

[0027] Detecting lift requires measuring the object with submillimeter accuracy (approximately 0.5 mm to 0.5 m). To remotely measure the shape of an object with high accuracy using LIDAR, it is necessary to focus the laser light on the target surface and increase the power locally to increase the scattered light.

[0028] In this embodiment, a three-dimensional measuring device is provided that can perform measurements with high accuracy even when the distance to the measurement target surface varies greatly.

[0029] First Embodiment Configuration of Three-Dimensional Measuring Apparatus FIG. 1 is a diagram showing an example of the configuration of a three-dimensional measuring apparatus.

[0030] FIG. 1 shows an example in which a three-dimensional measuring device 100 is installed on a cart 10, and a wall surface (surface) 2 of a tunnel structure 1 is measured from above the cart 10. The cart 10 is manually pushed by a person and moves on rails 11. In this embodiment, the tunnel structure 1 is an example of a concrete structure. The tunnel structure 1 is also an example of an object to be measured, and its wall surface 2 is an example of a surface to be measured. The three-dimensional measuring device 100 is also an example of a measuring device.

[0031] FIG. 2 is a diagram illustrating an example of the configuration of a three-dimensional measurement apparatus.

[0032] As shown in FIG. 2, the three-dimensional measuring device 100 includes a measuring unit 110, a light source unit 120, a power supply unit 130, a control unit 140, and the like.

[0033] [Measurement Unit] The measurement unit 110 scans a light beam on an object to measure the distance to the object. In this embodiment, the measurement unit 110 is configured as a FMCW (Frequency Modulated Continuous Waves) LIDAR (FMCW LIDAR). The FMCW LIDAR continuously irradiates the object with laser light while modulating the frequency, and calculates the distance to the object from the frequency of the received wave reflected by the object and returned.

[0034] FIG. 3 is a diagram showing an example of the configuration of a measurement unit configured with an FMCW lidar.

[0035] As shown in FIG. 3, the measurement unit 110 includes a beam splitter 111, a reference mirror 112, a focus adjustment unit 113, a scanning unit 114, and a light detection unit 115.

[0036] The beam splitter 111 splits the laser light supplied from the light source unit 120 into reference light and measurement light. The reference light is emitted toward a reference mirror 112, and the measurement light is emitted toward a focus adjustment unit 113. The reference light is reflected by the reference mirror 112 and enters the beam splitter 111 again. The measurement light enters the scanning unit 114 via the focus adjustment unit 113.

[0037] The focus adjustment unit 113 adjusts the focal position of the measurement light. As an example, in this embodiment, the focus lens is moved back and forth along the optical axis to adjust the focal position of the measurement light. The focus adjustment unit 113 includes a focus lens and an actuator that drives the focus lens. Note that the focus adjustment method is not limited to this. Alternatively, for example, the focus lens may be configured as a liquid lens, and the focal position may be adjusted by changing the curvature of the lens.

[0038] The scanning unit 114 polarizes the measurement light that has passed through the focus adjustment unit 113 and scans the measurement light on the object.

[0039] FIG. 4 is a conceptual diagram of scanning by the scanning unit.

[0040] As shown in Figure 4, in this embodiment, a polygon mirror (polygonal mirror) PM is used to scan the measurement light onto the object. The polygon mirror PM rotates around the θ axis, thereby reflecting and deflecting the incident light in a direction around the θ axis (θ direction). In this embodiment, the polygon mirror PM is further rotated around the φ axis to deflect the incident light in a direction around the φ axis (φ direction). The φ axis passes through the center of the polygon mirror PM and is perpendicular to the θ axis.

[0041] FIG. 5 is a diagram showing methods of incident measurement light onto a polygon mirror. FIG. 5 shows two incident methods. FIG. 5(A) shows a first incident method, and FIG. 5(B) shows a second incident method. The first incident method shown in FIG. 5(A) is a method in which the measurement light is incident onto the polygon mirror PM via two mirrors M1 and M2. The second incident method shown in FIG. 5(B) is a method in which the measurement light is directly incident onto the polygon mirror PM. Either incident method may be used. The incident position of the measurement light also rotates around the φ axis in conjunction with the rotation of the polygon mirror PM around the φ axis.

[0042] According to this configuration, by rotating the polygon mirror PM around the θ axis, the measurement light is scanned in the θ direction. Furthermore, by rotating the polygon mirror PM around the φ axis, the position scanned in the θ direction is displaced in the φ direction. Therefore, by rotating the polygon mirror PM around the θ axis while also rotating it around the φ axis, the measurement light can be scanned onto the object. Scanning in the θ direction is defined as main scanning, and the θ direction is defined as the main scanning direction. Furthermore, scanning in the φ direction is defined as sub-scanning, and the φ direction is defined as the sub-scanning direction. In this embodiment, the polygon mirror PM is an example of a light emission portion. Furthermore, the φ axis is an example of an axis intersecting the sub-scanning direction.

[0043] The polygon mirror PM is driven by a θ-axis motor 114A to rotate around the θ-axis. The polygon mirror PM is also driven by a φ-axis motor 114B to rotate around the φ-axis. The speed Vθ at which the polygon mirror PM rotates around the θ-axis is faster than the speed Vφ at which the polygon mirror PM rotates around the φ-axis (Vθ>Vφ). That is, in this embodiment, the scanning speed of the measurement light in the main scanning direction (Vθ) is faster than the scanning speed Vφ in the sub-scanning direction.

[0044] 3 , the measurement light that is irradiated toward the object and reflected by the object is incident on the beam splitter 111 via the scanning unit 114 and the focus adjustment unit 113. The reflected light of the measurement light that has entered the beam splitter 111 is combined with the reflected light of the reference light and output to the light detection unit 115 as interference light.

[0045] The light detection unit 115 converts the interference light output from the beam splitter 111 into an electrical signal. This electrical signal contains a signal component with a frequency corresponding to the difference between the frequency of the measurement light and the frequency of the reference light. This signal component is called a beat signal. The frequency of the beat signal is also called the beat frequency. There is a correlation between the beat frequency and the distance to the object. Therefore, the distance to the object can be calculated based on the beat frequency.

[0046] [Light Source Unit] The light source unit 120 supplies measurement laser light to the measurement unit 110. As described above, in this embodiment, the measurement unit 110 is configured with an FMCW LIDAR. Therefore, the light source unit 120 supplies laser light whose frequency is periodically modulated. As an example, in this embodiment, an FSF laser (Frequency-Shifted Feedback Laser) is supplied as the measurement laser light.

[0047] [Power Supply Unit] The power supply unit 130 includes a battery and supplies power to each component of the three-dimensional measurement device 100 .

[0048] [Control Unit] The control unit 140 controls the overall operation of the three-dimensional measuring apparatus 100. The control unit 140 also processes the data measured by the measuring unit 110.

[0049] FIG. 6 is a diagram illustrating an example of a hardware configuration of the control unit.

[0050] The control unit 140 has a configuration similar to that of a general computer, and includes a processor 141, a main memory 142, an auxiliary memory 143, an operation unit 144, a display unit 145, and an interface (I / F) 146.

[0051] The processor 141 executes programs and functions as various processing units. As an example, in this embodiment, the processor 141 is configured as a CPU (Central Processing Unit). Various programs and data executed by the processor 141 are stored in the main memory unit 142 and / or the auxiliary memory unit 143. The term "program" is synonymous with "software."

[0052] The main storage unit 142 includes a RAM (Random Access Memory) and a ROM (Read Only Memory). The RAM is used as a work area for the processor 141. The ROM stores a basic input / output program and the like.

[0053] The auxiliary storage unit 143 is configured by, for example, a hard disk drive (HDD), a solid state drive (SSD), or the like.

[0054] The operation unit 144 is composed of, for example, a keyboard, a mouse, and the like.

[0055] The display unit 145 is configured by, for example, a liquid crystal display (LCD), an organic electroluminescence diode display (OLED display), or the like.

[0056] The interface section 146 includes various connection interfaces for connecting the measurement unit 110, the light source unit 120, the power supply unit 130, and the like.

[0057] [Functions of the Control Unit] FIG. 7 is a block diagram of the main functions of the control unit regarding measurement control.

[0058] 7, with regard to measurement control, the control unit 140 has functions such as a scan control unit 140A, a focus control unit 140B, a signal processing unit 140C, and a recording control unit 140D. The functions of each unit are realized by the processor 141 executing a predetermined program.

[0059] [Scanning Control Unit] The scanning control unit 140A controls the scanning of the measurement light by the measurement unit 110. The scanning control unit 140A controls the scanning unit 114 of the measurement unit 110 to control the scanning of the measurement light. As described above, in this embodiment, the polygon mirror PM is rotated around the θ axis and the φ axis to scan the measurement light onto the object. The scanning control unit 140A controls the driving of the θ axis motor 114A and the φ axis motor 114B to control the scanning of the measurement light.

[0060] [Focus Control Unit] The focus control unit 140B controls the focusing of the measurement light. In this embodiment, the focus control unit 140B controls the focusing of the measurement light during scanning in the sub-scanning direction.

[0061] 8 to 10 are conceptual diagrams of focusing control. FIG. 8 shows the state of scanning of the measurement light by the three-dimensional measuring device 100 of this embodiment. FIG. 9 shows the state of focusing of the measurement light during scanning in the main scanning direction. FIG. 10 shows the state of focusing of the measurement light during scanning in the sub-scanning direction. FIG. 10 corresponds to the 10-10 cross section of FIG. 9.

[0062] As described above, in the three-dimensional measuring apparatus 100 of this embodiment, the measurement light is focused during scanning in the sub-scanning direction. As an example, in this embodiment, the measurement light is focused at the timing when the measurement light is emitted perpendicular to the φ axis. That is, focusing control is performed so that the measurement light emitted perpendicular to the φ axis is focused on the target surface. As a result, as shown in FIG. 10 , the measurement light emitted perpendicular to the φ axis is focused on the target surface. That is, the light is condensed on the target surface. On the other hand, since focus adjustment is not performed during scanning in the main scanning direction, the degree of condensation of the measurement light decreases as it approaches both ends in the main scanning direction.

[0063] By focusing the measurement light on the target surface, increasing the power locally, and increasing the scattered light, high-precision measurement is possible even from a distance. As described above, the degree of focusing decreases in the main scanning direction as one approaches both ends. Therefore, the measurement range in the main scanning direction is set within a range that ensures a predetermined level of precision. In other words, the measurement range is set within a range in which light can be focused below a threshold value.

[0064] The focus control unit 140B controls the focus adjustment unit 113 to control the focusing of the measurement light in the sub-scanning direction. Specifically, focusing control is performed at the timing when the measurement light is emitted perpendicular to the φ axis. At this time, focusing is performed using the distance measurement result obtained in the previous main scanning. As an example, focusing is performed using the distance measurement result obtained in the immediately previous main scanning. That is, in this embodiment, focusing in the next main scanning is performed using the distance measurement result obtained in the immediately previous main scanning. The amount of displacement of the scanning position in the sub-scanning direction is minute. Therefore, it can be used as distance measurement information for focusing in the next main scanning. This allows the measurement light to be continuously focused on the target surface in the sub-scanning direction.

[0065] The focus control unit 140B acquires information on the distance measurement result obtained in the immediately preceding main scan from the signal processing unit 140C and controls focusing in the sub-scanning direction. For the immediately preceding main scan measurement result, for example, the measurement result at the position where the measurement light is emitted perpendicular to the φ axis is used.

[0066] [Signal Processing Unit] The signal processing unit 140C processes the beat signal for each scanning position output from the light detection unit 115, and calculates the distance for each scanning position.

[0067] [Recording Control Unit] The recording control unit 140D records the distance information for each scanning position calculated by the signal processing unit 140C in the measurement data storage unit 140E. The measurement data storage unit 140E is configured by the auxiliary storage unit 143, for example.

[0068] [Measurement Operation by Three-Dimensional Measuring Apparatus] Three-dimensional measurement of an object by three-dimensional measuring apparatus 100 of this embodiment configured as described above is performed as follows.

[0069] Fig. 11 is a conceptual diagram of measurement, showing an example of three-dimensional measurement of a wall surface 2 of a tunnel structure 1 having an arc-shaped cross section.

[0070] The axial direction of the tunnel structure 1 is set as the main scanning direction, and the circumferential direction is set as the sub-scanning direction, and the wall surface 2 of the tunnel structure 1 is scanned with measurement light for three-dimensional measurement. The axial direction of the tunnel structure 1 is the same as the laying direction of the rails 11 and the same as the moving direction of the bogie 10. Note that "same" here does not mean completely identical, but means that they can be regarded as the same. In other words, it is a concept that includes a range of almost identical.

[0071] 11, the measurement is performed up to the boundary with the ground surface 3. With one boundary as the start point P0 and the other boundary as the end point P1, sub-scanning is performed in the circumferential direction, and the wall surface 2 is measured in three dimensions over a predetermined measurement width.

[0072] In this embodiment, the main scan is performed by rotating the polygon mirror PM around the θ axis, and the sub-scan is performed by rotating it around the φ axis. Therefore, the φ axis is set to be approximately parallel to the axis Tz of the tunnel structure 1, and the wall surface 2 is scanned.

[0073] During scanning, the focus of the measurement light is adjusted. In this embodiment, the focus is adjusted so that the wall surface 2 is in focus during scanning in the sub-scanning direction.

[0074] In the case of a tunnel structure, even if it has an arc-shaped cross-sectional shape, if the position of the axis Tz of the tunnel structure 1 does not coincide with the position of the φ axis, the distance (separation distance) r to the wall surface 2 will fluctuate greatly during sub-scanning.

[0075] FIG. 12 is a diagram illustrating the change in the separation distance during sub-scanning.

[0076] 12A is a diagram showing the relationship between the emission position and irradiation position of the measurement light. In the figure, the symbol EP indicates the emission position of the measurement light ML, and SP indicates the irradiation position of the measurement light ML. The distance r from the emission position EP to the irradiation position SP is calculated using the calculation formula in the figure. The angle Φ corresponds to the rotation angle of the polygon mirror PM around the φ axis. Note that the angle Φ is set to 0° when the measurement light ML is emitted horizontally.

[0077] In FIG. 12B, the radius R of the tunnel structure 1 is 4350 mm, and the emission position EP of the measurement light ML is x １ = 1750 mm, y １ 12B is a graph showing the relationship between the angle Φ and the distance r when the angle Φ is set to 1050 mm. As shown in FIG. 12B, the distance r changes as the angle Φ changes. That is, the distance to the target surface (wall surface) changes during sub-scanning.

[0078] FIG. 13 is a diagram showing another example of the change in the distance to the wall surface during sub-scanning.

[0079] 13A shows an example in which the cross section of the tunnel structure 1 is rectangular. Fig. 13A is a diagram showing the relationship between the emission position and the irradiation position of the measurement light. Fig. 13B shows the relationship between the width X of the tunnel structure 1 in the x-axis direction (horizontal direction) of 1700 mm, the width Y in the y-axis direction (vertical direction) of 4230 mm, the emission position EP of the measurement light ML of C = 1700 mm, and the irradiation position EP of the measurement light ML of C = 1700 mm. １ 10 is a graph showing the relationship between the angle Φ and the distance r when the angle Φ is set to φ = 685 mm. In this case, the distance r also changes as the angle Φ changes. In other words, the distance to the target surface (wall surface) changes in the sub-scanning direction. In the case of a rectangular cross section, even if the position of the axis of the tunnel structure and the position of the φ axis are aligned, the distance to the target surface changes in the sub-scanning direction.

[0080] In the three-dimensional measuring apparatus 100 of this embodiment, when the distance to the target surface (wall surface) changes in the sub-scanning direction, the focus of the measuring light is adjusted to follow the change in distance.

[0081] The focus adjustment is performed using the distance measurement results obtained in the previous main scan. That is, the focus adjustment in the next main scan is performed using the distance measurement results obtained in the previous main scan. This allows the measurement light to be continuously focused on the target surface in the sub-scanning direction.

[0082] As described above, according to the three-dimensional measuring apparatus 100 of this embodiment, focusing is performed by scanning in the sub-scanning direction. This allows the object to be measured with high accuracy even if the distance to the object surface changes due to the sub-scanning. In other words, since the measurement light can be focused on the object surface, high-accuracy measurement is possible even from a remote location.

[0083] FIG. 14 is a diagram showing a conceptual diagram of the measurement results.

[0084] FIG. 14 shows an example of the measurement results when the wall surface 2 of a tunnel structure 1 having an arc-shaped cross section is measured in three dimensions.

[0085] By scanning the wall surface 2 of the tunnel structure 1 once in the circumferential direction, three-dimensional measurement data of the wall surface 2 can be obtained with a width (measurement width) corresponding to the measurement range in the main scanning direction. The obtained data is distance data for each scanning position. Data on the three-dimensional shape of the wall surface 2 can be obtained from the three-dimensional measurement data of the wall surface 2. Furthermore, in the case of the tunnel structure 1, data on the three-dimensional shape of the internal space can be obtained.

[0086] [Variations] [Variations of focusing in the sub-scanning direction] In the above embodiment, the measurement results of the previous main scan are used to perform focusing for the next main scan, but the method of focusing in the sub-scanning direction is not limited to this.

[0087] FIG. 15 is a diagram showing another example of focusing in the sub-scanning direction.

[0088] As shown in FIG. 15 , the three-dimensional measuring device of this example is equipped with a ranging unit 150 separate from the measuring unit 110. The ranging unit 150 measures the distance to the target surface in the sub-scanning direction. When the target is a tunnel structure, the sub-scanning direction is set to the circumferential direction. Therefore, when the target is a tunnel structure, the ranging unit 150 measures the distance to the target surface (wall surface) along the circumferential direction. The measurement method is not particularly limited. As an example, a ToF (Time Of Flight) type LIDAR (ToF LIDAR) can be used. In addition, for example, a method using radio waves such as millimeter waves for measurement, a method using ultrasonic waves for measurement, or a method using infrared rays for measurement can also be used.

[0089] Note that the distance measurement unit 150 does not necessarily need to measure the distance across the entire measurement width of the measurement unit 110. It is sufficient to be able to measure the distance at the position where focusing is performed in the sub-scanning direction. For example, when the measurement light is focused at a position where it is emitted perpendicular to the φ axis, it is sufficient to be able to measure the distance at least at the position where the measurement light is emitted perpendicular to the φ axis. Therefore, it is sufficient to be able to measure the distance at at least one cross section.

[0090] FIG. 16 is a diagram showing another example of focusing in the sub-scanning direction.

[0091] As shown in FIG. 16, in the three-dimensional measuring apparatus of this example, a control unit 140 has the functions of an information acquisition unit 140F, a distance calculation unit 140G, and the like.

[0092] The information acquisition unit 140F acquires various information necessary for measurement, including information about the object (object information), information about the measurement position (measurement position information), and the like.

[0093] The object information includes information such as the shape and size of the object. The information such as the shape and size of the object is made up of, for example, design data of the object. The design data is made up of, for example, drawing data, CAD (Computer Aided Design) data, etc.

[0094] The measurement position is information about the relative position of the object relative to the three-dimensional measuring device 100. When the object is a tunnel structure, the position of the three-dimensional measuring device 100 within the tunnel corresponds to the measurement position.

[0095] Distance calculation section 140G calculates the distance to the target surface (wall surface) in the sub-scanning direction based on information on the measurement position and information on the shape and size of the target.

[0096] The focus control unit 140B controls the focusing of the measurement light in the sub-scanning direction based on the distance information calculated by the distance calculation unit 140G.

[0097] In the above embodiment, the measuring light is focused at the timing when the measuring light is emitted in the direction perpendicular to the φ axis, but the position where the focusing is performed is not limited to this. For example, the focusing may be performed at the position of one end of the main scanning direction (the start point or end point of the main scanning).

[0098] Furthermore, in the above embodiment, the measurement results obtained in the immediately preceding main scan are used to adjust the focus for the next main scan, but the measurement results used do not necessarily have to be those from the immediately preceding main scan.

[0099] Furthermore, in the above embodiment, focusing in the sub-scanning direction is performed after each main scan, but focusing in the sub-scanning direction may be performed after n main scans. For example, in a configuration in which main scans are performed using a polygon mirror, focusing in the sub-scanning direction may be performed after n rotations of the polygon mirror.

[0100] [Modification of Measurement Method] In the above embodiment, the measurement unit 110 is configured as an FMCW LIDAR, but it is also possible to configure the measurement unit 110 as a ToF LIDAR. However, in order to measure remote locations with high accuracy, it is preferable to employ an FMCW LIDAR.

[0101] [Variations of Scanning Method] In the above embodiment, a polygon mirror is used as a means for deflecting the measurement light in the main scanning direction, but the means for deflecting the measurement light in the main scanning direction is not limited to this. Alternatively, for example, a galvanometer mirror, a MEMS (Micro Electro Mechanical Systems) mirror, or other deflecting means may be used to deflect the measurement light in the main scanning direction.

[0102] In the above embodiment, the polygon mirror is rotated around the φ axis to deflect the measurement light in the sub-scanning direction, but the means for deflecting the measurement light in the sub-scanning direction is not limited to this. For example, the position or direction of the light incident on a deflector such as a polygon mirror may be changed along the sub-scanning direction to deflect the measurement light in the sub-scanning direction.

[0103] The deflection in the sub-scanning direction may be configured to be continuous or intermittent. When the deflection is intermittent, for example, the scanning position is displaced in the sub-scanning direction for each main scan. In the configuration of the above embodiment, the polygon mirror PM is rotated by a predetermined angle around the φ axis for each main scan to deflect the measurement light in the sub-scanning direction.

[0104] Second Embodiment Here, a configuration for continuous three-dimensional measurement of a tunnel structure along its axial direction will be described, that is, a configuration for three-dimensional measurement of the entire length of the tunnel structure will be described.

[0105] FIG. 17 is a diagram showing a schematic configuration of a three-dimensional measurement device.

[0106] To measure the entire length of a tunnel structure in three dimensions, it is necessary to measure while changing the position along the axial direction of the tunnel structure. When measuring while changing the position, it is necessary to identify the measurement position.

[0107] As shown in FIG. 17, the three-dimensional measuring apparatus 100 of this embodiment includes a position measuring unit 160 in order to identify the measurement position by the three-dimensional measuring apparatus 100 .

[0108] The configuration of the three-dimensional measuring device 100 of the first embodiment is substantially the same as that of the three-dimensional measuring device 100 of the first embodiment, except for the inclusion of the position measurement unit 160. Therefore, only the position measurement unit 160 and the measurement method for a tunnel structure using the three-dimensional measuring device 100 will be described here.

[0109] [Position Measurement Unit] The position measurement unit 160 measures the position (measurement position) of the three-dimensional measuring device 100. As described above, the measurement position is the relative position of the three-dimensional measuring device 100 with respect to the object. When the object is a tunnel structure 1, the position of the three-dimensional measuring device 100 inside the tunnel is measured.

[0110] In this embodiment, the three-dimensional measuring device 100 is installed on a cart 10, and the measurement position is displaced by moving the cart 10. The cart 10 is an example of a moving body.

[0111] In this embodiment, a carriage 10 moves on rails 11. That is, in this embodiment, a three-dimensional measuring device 100 moves (displaces) along a specified path within the tunnel. If the position of the rails 11 relative to the tunnel structure 1 is known, the measurement position can be identified by the movement distance from a reference position. The reference position can be, for example, the end (opening) of the tunnel structure 1.

[0112] In this embodiment, the position measurement unit 160 has a travel distance measurement unit 160A that measures the travel distance of the bogie 10. The travel distance measurement unit 160A measures the travel distance of the bogie 10, for example, by measuring the number of rotations of the wheels of the bogie 10. Specifically, the number of rotations of the wheels is measured, and the travel distance of the bogie 10 is measured based on the known circumference or outer diameter of the wheels.

[0113] In this embodiment, in order to perform position detection with higher accuracy, the amount of lateral deviation of the bogie 10 on the rail 11 is measured. That is, the amount of deviation in a direction perpendicular to the traveling direction is measured. The position measurement unit 160 has a lateral deviation measurement unit 160B that measures the amount of lateral deviation of the bogie 10. The lateral deviation measurement unit 160B measures, for example, the amount of deviation of the bogie 10 in the lateral direction (the axial direction of the wheels) relative to the rail 11. The measurement method is not particularly limited.

[0114] The position measurement unit 160 outputs a set of information on the movement distance measured by the movement distance measurement section 160A and information on the amount of lateral displacement measured by the lateral displacement measurement section 160B to the control unit 140 as information on the measured position.

[0115] The control unit 140 associates the distance information at each scanning position measured by the measurement unit 110 with the information on the measurement position measured by the position measurement unit 160, and records the information in the measurement data storage unit 140E.

[0116] [Three-dimensional measurement of a tunnel structure] Here, an example will be described in which design data for the tunnel structure 1 exists and the shape, size, etc. are known. In this case, focusing in the sub-scanning direction is possible using the design data for the tunnel structure 1.

[0117] In this example, a case will be described in which measurement and movement are repeated to perform three-dimensional measurement over the entire length of the tunnel structure 1. That is, the movement is stopped during measurement, and after measurement of one circumference is completed, movement to the next measurement position is repeated to perform measurement over the entire length.

[0118] FIG. 18 is a flowchart showing an example of a measurement procedure.

[0119] First, object information is acquired (step S1). Here, information including design data of the tunnel structure is acquired. As described above, information necessary for focusing in the sub-scanning direction can be acquired from the design data. Furthermore, it becomes possible to identify the measurement position and the scanning position from the design data.

[0120] Next, information on the measurement position is acquired (step S2). The measurement position is identified from the movement distance from a predetermined reference position and the amount of lateral deviation.

[0121] Next, the scanning position is calculated (step S3). That is, the position where the wall surface 2 of the tunnel structure 1 is scanned is calculated.

[0122] Next, the focusing position is calculated (step S4). That is, the focusing position in the sub-scanning direction is calculated. When measuring the tunnel structure 1, the sub-scanning direction is set to the circumferential direction of the tunnel structure 1. Therefore, the main scanning direction is the axial direction of the tunnel structure 1. The axial direction of the tunnel structure 1 is essentially synonymous with the movement direction (travel direction) of the carriage 10.

[0123] After calculating the focusing position, three-dimensional measurement is performed (step S5). That is, the wall surface 2 is scanned with the measurement light to perform three-dimensional measurement of the wall surface 2. At this time, the measurement light is focused by scanning in the sub-scanning direction. This makes it possible to measure the distance to the wall surface 2 with high accuracy even if the separation distance to the wall surface 2 changes.

[0124] The measurement is performed up to the boundary with the ground (see FIG. 11). Sub-scanning is performed in the circumferential direction from one boundary to the other boundary, and the wall surface 2 is measured in three dimensions.

[0125] The measured distance information for each scanning position is associated with the information on the measurement position and recorded in the measurement data storage unit 140E (step S6).

[0126] After completing the measurement for one circumference, it is determined whether the measurement position is the measurement end position (step S7), that is, whether the measurement for the entire length has been completed.

[0127] If the end position has been reached, the measurement is terminated. On the other hand, if the end position has not been reached, the measurement is performed by moving (step S8) to carry out measurement at the next measurement position. The movement is performed by an amount corresponding to the measurement width. At this time, the movement is performed so that the measurement ranges of adjacent measurement positions overlap to prevent measurement omissions.

[0128] In this way, by repeating the movement and measurement, the entire length of the tunnel structure 1 can be measured in three dimensions.

[0129] By integrating the measurement data for each measurement position (measurement data for the distance at each scanning position), measurement data for the entire length is obtained. The measurement data for the entire length constitutes data that indicates the three-dimensional shape of the wall surface 2 of the tunnel structure 1. In addition, this data constitutes data that indicates the three-dimensional shape of the internal space of the tunnel structure 1.

[0130] The measurement results are used for diagnosing floating as a concrete deterioration diagnosis, as well as for measuring displacement inside a tunnel, measuring peeling, spalling, and spall marks on concrete, etc. In other words, they are used for measuring and diagnosing things that can be correlated with surface displacement. In other words, the three-dimensional measuring device 100 of this embodiment is suitable for use in these measurements, diagnoses, etc.

[0131] [Modifications] [Modifications of measurement method] In the above embodiment, the movement of the carriage 10 is stopped during measurement, but it may be configured to measure while moving. That is, it may be configured to scan while moving. In this case, it is preferable to set the scanning speed in the sub-scanning direction to be faster than the movement speed of the carriage 10 during measurement. That is, it is preferable to set the movement speed of the carriage 10 to be slower than the scanning speed in the sub-scanning direction. This makes it possible to prevent measurement omissions.

[0132] Furthermore, during sub-scanning, the polygon mirror PM may be configured to rotate continuously around the φ axis, or to reciprocate within the measurement range in the sub-scanning direction (measurement range in the circumferential direction) for sub-scanning. In other words, the polygon mirror PM may be configured to rotate around the φ axis within a predetermined rotation angle range for sub-scanning.

[0133] [Variations of the Method for Identifying the Measurement Position] In the above embodiment, the measurement position is identified by measuring the travel distance and lateral deviation of the carriage 10 moving on the rail 11, but the method for identifying the measurement position is not limited to this. For example, a configuration can be adopted in which the measurement position is identified using a self-position estimation technique using SLAM (Simultaneous Localization and Mapping). The SLAM technique itself is well known, so a detailed description thereof will be omitted. SLAM using lidar, SLAM using a camera, etc. can also be adopted.

[0134] Other configurations for positioning may include a positioning system using a beacon, an Indoor Messaging System (IMES), a Wi-Fi (registered trademark), a positioning system using Ultra-Wideband (UWB), etc. Also, various sensors such as an acceleration sensor, a magnetic sensor, and an angular velocity sensor may be installed on the cart 10 or the three-dimensional measuring device 100, and the measurement position may be estimated based on values ​​obtained from each sensor.

[0135] Furthermore, in a configuration in which the moving distance and lateral deviation amount of the carriage 10 are measured to identify the measurement position, the lateral deviation amount may be obtained using the measurement results of the three-dimensional measuring device 100 .

[0136] [Variations of the Method for Changing the Measurement Position] In the above embodiment, the three-dimensional measuring device 100 is installed on a cart 10 that is manually pushed by a person and moves on rails 11, and the measurement position is changed by moving the cart 10. However, the method for changing the measurement position of the three-dimensional measuring device 100 is not limited to this. The three-dimensional measuring device 100 may be installed on an automatically traveling cart to change the measurement position. Furthermore, the three-dimensional measuring device 100 may be installed on a cart, an automobile, a train, or the like, and measurement may be performed thereon. Furthermore, the three-dimensional measuring device 100 may be mounted on a self-propelled robot, an unmanned aerial vehicle (drone), or the like, and measurement may be performed thereon. When a cart is used as the moving body, the cart does not necessarily have to run on rails, but a cart that runs directly on the ground can also be used. Furthermore, a cart that is manually pushed by a person and moves thereon may be equipped with a so-called electric assist mechanism.

[0137] Other Embodiments Control Unit of Three-Dimensional Measuring Apparatus The functions of the control unit 140 constituting the three-dimensional measuring apparatus 100 are realized by various processors. The various processors include a CPU, which is a general-purpose processor that executes programs and functions as various processing units, and / or a dedicated electrical circuit, which is a processor having a circuit configuration specifically designed to execute specific processing, such as a GPU (Graphic Processing Unit), a Programmable Logic Device (PLD), which is a processor whose circuit configuration can be changed after manufacture, such as an FPGA (Field Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit). The term "program" is synonymous with "software."

[0138] A single processing unit may be composed of one of these various processors, or may be composed of two or more processors of the same or different types. For example, a single processing unit may be composed of multiple FPGAs, or a combination of a CPU and an FPGA. Furthermore, multiple processing units may be composed of a single processor. Examples of multiple processing units composed of a single processor include: a first configuration, as typified by computers used as clients or servers, in which a single processor is composed of a combination of one or more CPUs and software, and this processor functions as multiple processing units; a second configuration, as typified by system-on-chip (SoC), in which a processor is used to realize the functions of an entire system including multiple processing units on a single IC (Integrated Circuit) chip; and a hardware structure, in which the various processing units are composed of one or more of the above-mentioned various processors.

[0139] [Measurement Object] In the above embodiment, the 3D measurement device 100 is used to measure a tunnel structure, but the measurement object is not limited to this. The device can be used for 3D measurement of concrete structures such as bridges and buildings.

[0140] Furthermore, as described above, the measurement results can be suitably used for diagnosing the floating of concrete as a deterioration diagnosis, as well as for measuring displacement inside tunnels, and measuring peeling, spalling, and traces of peeling of concrete.

[0141] [Others] The above-described embodiments and their modifications can be used in appropriate combinations.

[0142] REFERENCE SIGNS LIST 1 Tunnel structure 2 Wall surface 3 Ground 10 Cart 11 Rail 100 Three-dimensional measuring device 110 Measurement unit 111 Beam splitter 112 Reference mirror 113 Focus adjustment unit 114 Scanning unit 114A θ-axis motor 114B φ-axis motor 115 Light detection unit 120 Light source unit 130 Power supply unit 140 Control unit 140A Scan control unit 140B Focus control unit 140C Signal processing unit 140D Recording control unit 140E Measurement data storage unit 140F Information acquisition unit 140G Distance calculation unit 141 Processor 142 Main memory unit 143 Auxiliary memory unit 144 Operation unit 145 Display unit 146 Interface unit 150 Distance measurement unit 160 Position measurement unit 160A Movement distance measurement unit 160B Lateral displacement measurement unit M1 Mirror M2 Mirror ML Measurement light PM Polygon mirror EP Emission position of measurement light SP Irradiation position of measurement light Tz Axis of tunnel structure

Claims

1. A measurement device that scans light onto an object to measure the distance to or shape of the object, comprising: a focus adjustment unit that adjusts the focus of the light; and a processor, wherein the processor controls the focus adjustment unit to focus the light on the object during scanning in the sub-scanning direction.

2. The measurement device according to claim 1, further comprising a movable body that displaces the measurement position, wherein the movable body moves in a direction that intersects with the sub-scanning direction.

3. The measurement device according to claim 1, wherein the scanning speed of the light in the main scanning direction is faster than the scanning speed in the sub-scanning direction.

4. The measurement device according to claim 2, wherein the scanning speed in the sub-scanning direction is faster than the moving speed of the movable body during measurement.

5. The measurement device according to claim 1, wherein the processor acquires design data of the object, and controls the focus adjustment unit based on the design data.

6. The measurement device according to claim 1, wherein the processor controls the focus adjustment unit based on the measurement results of a previous main scan.

7. The measurement device according to claim 1, further comprising a distance measurement unit, wherein the processor controls the focus adjustment unit based on the distance measurement result of the distance measurement unit.

8. The measurement device according to claim 1, wherein the light emitting portion rotates around an axis intersecting the sub-scanning direction to perform scanning in the sub-scanning direction.

9. The measurement device according to claim 1, wherein the light from a light source is scanned in a main scanning direction by a polygon mirror, a galvanometer mirror, or a MEMS mirror, and scanning in the sub-scanning direction is performed by rotating the polygon mirror, the galvanometer mirror, or the MEMS mirror around an axis intersecting the sub-scanning direction.

10. The measurement device according to claim 1, wherein the light having a periodically modulated frequency is scanned.

11. The measurement device according to claim 1, wherein the object is a tunnel structure, and the sub-scanning direction is the circumferential direction of the tunnel structure.

12. The measurement device according to claim 2, wherein the processor acquires information on measurement positions and generates three-dimensional shape data of the object based on information on the measurement results for each measurement position.

13. The measurement device according to claim 12, wherein, when measuring by moving along a preset route, the amount of movement of the moving body and the amount of deviation from the route are measured to obtain information on the measurement position.

14. The measurement device according to claim 12, wherein the information on the measurement position is acquired using self-position estimation by SLAM.

15. A measurement method for measuring the distance to or shape of an object by scanning light on the object, wherein the light is focused on the object during scanning in the sub-scanning direction.

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