Measuring device, measuring system and measuring method

Abstract

An embodiment of the technology of the present application provides a measuring device, a measuring system, and a measuring method capable of calibrating a Doppler shift with high precision. In the measuring device according to an embodiment of the present application, a processor performs the following processing: acquires first scan data including information indicating a first distance from a laser scanner to a measured portion of an object, the first distance being obtained by scanning the measured portion of the object in a first direction with the laser scanner; acquires second scan data including information indicating a second distance from the laser scanner to the measured portion of the object, the second distance being obtained by scanning the measured portion of the object in a second direction different from the first direction with the laser scanner; and calculates post-calibration data in which the influence of a Doppler shift in the first scan data and the second scan data is removed, by performing an averaging process on the first scan data and the second scan data.

Description

Technical Field

[0001] This invention relates to a measuring device, a measuring system, and a measuring method, and more particularly to a technique for measuring an object using a laser beam. Background Technology

[0002] In recent years, the inspection and maintenance of so-called "social infrastructure structures" such as roads, bridges, tunnels, dams, and buildings (understanding the condition of the structures and repairing them accordingly), specifically identifying the presence or extent of defects (or damage) such as cracks, "lifting," or peeling, has become a significant social issue. Additionally, "infra" is an abbreviation for "infrastructure."

[0003] In the past, workers would visually inspect or tap objects to identify defects. However, this method requires time and effort and is sometimes difficult to access.

[0004] Therefore, to address this situation, technologies are being researched that utilize laser beams for non-contact measurement of objects, detecting defects based on measurements of minute irregularities (three-dimensional shapes). In this type of measurement, when social infrastructure structures are considered, high-speed scanning and high-precision detection are required, depending on the type and size of the object. However, a problem exists where measurement accuracy (range accuracy) decreases due to Doppler displacement if the scanner moves relative to the object being measured.

[0005] As a technology for addressing this problem, Patent Document 1 is known, for example. Patent Document 1 describes a technique for calibrating Doppler displacement when measuring a moving object with a fixed measuring head. Specifically, a sample of the object being measured is moved at multiple speeds, the difference between these speeds is calculated as a calibration speed, and then the difference in the frequencies of the reflected light at these speeds is calculated as a frequency displacement.

[0006] Previous technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2020-046368 Summary of the Invention

[0009] The technical problem to be solved by the invention

[0010] When using a laser beam for measurement, depending on the type or size of the object being measured (e.g., a social infrastructure structure), it is sometimes difficult (actually impossible) to move or rotate the object itself. In such cases, the measurement angle changes as the optical axis direction changes during scanning. However, this situation is not considered in Patent Document 1. Furthermore, depending on the object being measured, as in Patent Document 1, pre-measurement is performed on the entire measuring unit, making it difficult to measure the angle at each point in the obtained point set. Also, depending on the object being measured, it is difficult to accurately aim at the same position for two measurements with different speeds.

[0011] Thus, in previous technologies, it was difficult to calibrate the Doppler displacement that accompanied changes in the scanning direction.

[0012] The present invention was made in view of this situation, and its object is to provide a measuring device, measuring system and measuring method capable of calibrating Doppler displacement with high precision.

[0013] means for solving technical problems

[0014] To achieve the above objectives, the measuring device according to the first aspect of the present invention includes a processor that performs the following processing: acquiring first scan data, the first scan data including information representing a first distance, the first distance being the distance from the laser scanner to the measured part obtained by scanning the measured part of an object with a laser scanner along a first direction; acquiring second scan data, the second scan data including information representing a second distance, the second distance being the distance from the laser scanner to the measured part obtained by scanning the measured part of an object with a laser scanner along a second direction different from the first direction; and calculating calibrated data after removing the influence of Doppler displacement in the first scan data and the second scan data by performing averaging processing on the first scan data and the second scan data.

[0015] In the first method, the first direction and the second direction can change over time.

[0016] That is, the first and second scan data are time-series data, and the measurement results include deviations from the true values ​​based on Doppler displacement.

[0017] Here, since the scanning directions (first direction and second direction) in the first scan data and the second scan data are different, it is assumed that the signs of the deviations from the true values ​​based on the Doppler displacement in the measurement results are opposite.

[0018] Therefore, averaging the first and second scan data can offset the effects of Doppler shift.

[0019] In addition, in the first method and the following methods, the first direction and the second direction can be opposite directions, but they may not be completely opposite directions.

[0020] Thus, the Doppler displacement can be calibrated with high precision using the measuring device involved in the first method.

[0021] In addition, in the first method and the following methods, the first and second scanning data may include distance data and scanning direction data (e.g., azimuth and elevation angles, or main scanning direction and sub-scanning direction), and may also include three-dimensional position data.

[0022] Distance and scanning direction are equivalent information that can be converted into each other.

[0023] Furthermore, the measuring device involved in the first method can be implemented, for example, as a processor part (the part that acquires and processes measurement data) of a measuring system, but is not limited to this method.

[0024] In the second method, the measuring device involves a processor that performs averaging processing corresponding to the distance between a first measuring point that has acquired first scan data and a second measuring point that has acquired second scan data, as described in the first method.

[0025] For example, different averaging processes can be implemented depending on whether the distance between the first and second measurement points is close or far.

[0026] In the third method, the measuring device involved in the second method involves the processor averaging the positions of the first and second measuring points during the averaging process.

[0027] In the third method, the "average" can be a simple average or a weighted average.

[0028] In the fourth method, the processor of the measuring device performs the following processing in the first or second method: for each measurement point of the first measurement point group for acquiring the first scan data, the first speed as the scanning speed is included in the first scan data; for each measurement point of the second measurement point group for acquiring the second scan data, the second speed as the scanning speed is included in the second scan data; and the first and second scan data are averaged using the first and second speeds.

[0029] In the fifth method, the measuring device in the fourth method calculates, during the averaging process, the positions of the points selected from the first measurement point group (i.e., the first point) and the points selected from the second measurement point group (i.e., the second point) as the calibrated data, which are the ratios of the absolute value of the first velocity at the first point to the absolute value of the second velocity at the second point.

[0030] In the 5th method, the processor of the measuring device involved in the 6th method sets the internal ratio to 1:1 for averaging.

[0031] Method 6 specifies the exact method for averaging.

[0032] In the 7th method, the measuring device, in the 5th or 6th method, performs an averaging process on all pairs of two points that are paired as point 1 and point 2 and the distance difference between point 1 and point 2 is below the reference value.

[0033] Method 7 specifies the method for selecting data as the object of averaging.

[0034] In the 8th method, the measuring device, in the 5th or 6th method, performs an averaging process on the points in the first measuring point group and the pairs of one or more second points selected from the second measuring point group in order of proximity to the first point.

[0035] Method 8 specifies other methods for selecting data as the object of averaging.

[0036] In the 9th method, the measuring device, in the 5th or 6th method, involves a processor that averages the second point and a pair of one or more first points selected from the first measuring point group in order of proximity to the second point.

[0037] Method 9 specifies another method for selecting data as the object of averaging.

[0038] The measuring device involved in the 10th method, in any of the 1st to 9th methods, allows the processor to use multiple calibrated data to measure the three-dimensional shape of the object.

[0039] Furthermore, the processor can evaluate damage (defects) such as buoyancy or peeling based on the measurement results.

[0040] In the 10th method, the measuring device involved in the 11th method extracts the damage candidate region of the object based on the measured three-dimensional shape, and outputs information representing the extracted damage candidate region to the output device.

[0041] The output device can be a display device or a recording device.

[0042] In the 11th method, the measuring device involved in the 12th method involves the processor performing the following processing: extracting the design information of the three-dimensional shape of the object and / or the area where the variation of the three-dimensional shape measurement results obtained in advance exceeds the reference as a damage candidate area.

[0043] In the 12th method, "design information" can be, for example, data from a CAD system (CAD: Computer Aided Design), and "pre-acquired measurement results of three-dimensional shapes" can be, for example, past measurement results.

[0044] Furthermore, for example, the determined threshold can be set as a "benchmark".

[0045] To achieve the above objectives, the measurement system according to the 13th aspect of the present invention includes: a measurement device according to any one of the 1st to 12th aspects; and a laser scanner.

[0046] In the measurement system of the 13th method, the Doppler displacement can be calibrated with high precision by having the measurement device of any of the 1st to 12th methods.

[0047] In addition, in the 13th method, the laser scanner preferably establishes a correlation between information indicating distance and information indicating laser irradiation direction and outputs the information.

[0048] The measuring device can utilize this output.

[0049] The measurement system involved in Method 14 is the same as that in Method 13, where the laser scanner is a laser scanner that uses a laser beam in a frequency-modulated continuous wave manner.

[0050] A frequency-modulated continuous wave laser (FMCW laser) is a laser beam that transmits a frequency-modulated continuous wave, which can determine the distance to an object based on the frequency difference (beat frequency) between the transmitted and reflected waves.

[0051] In measurements using frequency-modulated continuous wave laser beams, the distance resolution is determined based on the "frequency change per unit time (modulation rate) and the measured resolution of the beat frequency".

[0052] The measurement system involved in Method 15 is the same as that in Method 14, where the laser scanner is a laser scanner that uses a frequency displacement feedback type laser beam.

[0053] "Frequency-Shifted Feedback Laser (FSF Laser)" is a type of frequency-modulated continuous wave laser.

[0054] To achieve the above objectives, the measurement method according to the 16th aspect of the present invention is executed by a measurement device equipped with a processor, the processor performing the following processing: acquiring first scan data, the first scan data including information representing a first distance, the first distance being the distance from the laser scanner to the measured part obtained by scanning the measured part of the object with a laser scanner along a first direction; acquiring second scan data, the second scan data including information representing a second distance, the second distance being the distance from the laser scanner to the measured part obtained by scanning the measured part of the object with a laser scanner along a second direction different from the first direction; and calculating calibrated data after removing the influence of Doppler displacement in the first scan data and the second scan data by performing averaging processing on the first scan data and the second scan data.

[0055] According to method 16, similarly to method 1, the Doppler displacement can be calibrated with high precision.

[0056] The measurement method involved in Method 16 can have the same structure as Methods 2 to 12.

[0057] Furthermore, non-transitory and tangible recording media (e.g., various optical-magnetic recording devices or semiconductor memories) that enable a measuring device equipped with a processor to execute these measurement methods and computer-readable code containing these programs can also be cited as embodiments of the present invention.

[0058] In addition, the term "non-temporary and tangible recording medium" does not include intangible recording media such as carrier signals or propagation signals themselves.

[0059] Invention Effects

[0060] As explained above, the measuring device, measuring system, and measuring method according to the present invention can calibrate Doppler displacement with high precision. Attached Figure Description

[0061] Figure 1 This is a diagram showing the structure of the measurement system according to the first embodiment.

[0062] Figure 2 This is an external view of the three-dimensional measuring device according to the first embodiment.

[0063] Figure 3 It is a diagram showing the structure of a three-dimensional measuring device.

[0064] Figure 4 This is a diagram illustrating an example of two-dimensional scanning.

[0065] Figure 5 This is another example of a two-dimensional scan.

[0066] Figure 6 It is a diagram showing the hardware structure of a data processing device.

[0067] Figure 7 This is a flowchart (1 / 2) illustrating the measurement method processing.

[0068] Figure 8 This is a flowchart illustrating the measurement method process (2 / 2).

[0069] Figure 9 This diagram illustrates the calibration process using both clockwise and counterclockwise measurement results.

[0070] Figure 10 It is a graph that represents the state of data acquired by scanning at each measurement point.

[0071] Figure 11 This is a graph showing the distance calibration using speed data.

[0072] Figure 12 It is a graph showing the velocity along the line of sight and the velocity along the tangential direction under different scanning directions.

[0073] Figure 13 This diagram illustrates the situation where the effects of Doppler displacement are counteracted by reverse scanning.

[0074] Figure 14 This is a graph representing an output example of a damage candidate region. Detailed Implementation

[0075] [The Influence of Doppler Displacement in Measurement]

[0076] In measurements using laser beams, as mentioned above, it is difficult to aim at the exact same point and take multiple measurements. Furthermore, asymmetrical mirrors (see reference) are used to change the direction of the laser beam. Figure 4 , Figure 5 In cases like the example described in Patent Document 1, the rotational speed can sometimes vary subtly depending on the rotational position. Because of this, the relative distance or relative velocity to the object changes during scanning, sometimes leading to a decrease in ranging accuracy (measurement precision) due to Doppler displacement. To address this problem, depending on the type or size of the object, it is difficult to move the object or scan at multiple speeds or measure the exact same point as described in Patent Document 1.

[0077] In view of this situation, the inventors of this application conducted in-depth research and arrived at the concept that "in both forward and reverse scanning, the signs of the deviations from the true values ​​based on Doppler displacement in the measurement data should be opposite. Therefore, if the measurement results based on forward scanning and those based on reverse scanning are averaged, the influence of Doppler displacement is canceled out, enabling high-precision measurement of distance (three-dimensional shape)." The embodiments of the present invention based on this concept will be described below.

[0078] [First Implementation]

[0079] The first embodiment of the measuring device, measuring system and measuring method involved in the present invention will be described in detail.

[0080] Figure 1 This is a diagram showing the structure of the measurement system according to the first embodiment. For example... Figure 1 As shown, the measurement system 1 (measurement system) is a system for measuring and inspecting railway tunnels, and includes a three-dimensional measurement device 10 (laser scanner), a data processing device 14 (measurement device, processor) and a power supply device 16.

[0081] In this example, the three-dimensional measuring device 10 is a LiDAR (Light Detection and Ranging), particularly a Frequency Modulated Continuous Wave (FMCW) LiDAR capable of ranging with an accuracy of hundreds of μm. However, the present invention is not limited to using ranging data (three-dimensional measurement data) measured by an FMCW LiDAR. Furthermore, the three-dimensional measuring device 10 is mounted on a tripod 12, but it can also be mounted on a trolley 18 that travels or moves on a track.

[0082] [Three-dimensional measuring device]

[0083] Figure 2 This is an external view of the three-dimensional measurement device 10 according to the first embodiment. The three-dimensional measurement device 10 includes an FMCW (Frequency Modulated Continuous Wave) LiDAR. Figure 2 As shown, the three-dimensional measuring device 10 is mounted on a trolley 18 traveling on a track, and measures the distance to the wall 20A (object, measured part) of the tunnel 20 (object). In addition to the three-dimensional measuring device 10, the trolley 18 also carries a data processing device 14 (processor) and a power supply device 16. The power supply device 16 supplies power to the three-dimensional measuring device 10 and the data processing device 14.

[0084] In the measurement system 1, the distance and direction up to the wall 20A and their rate of change can be measured by the three-dimensional measuring device 10, and as will be described in detail later, the three-dimensional shape of the wall 20A (object) can be measured using multiple calibrated data.

[0085] exist Figure 2 In the example shown, the three-dimensional measuring device 10 is in Figure 2 A high-speed FSF laser beam, representing one mode of FMCW (Flexible Multi-Functional) scanning, is used to scan the wall surface 20A in the left-right direction (main scanning direction), and the scan line is moved in the up-down direction (sub-scanning direction) of the wall surface 20A. Thus, measurements are taken from the laser scanner 15 (reference) of the three-dimensional measuring device 10. Figure 3 The distances to multiple measurement points along each scan line of the laser beam are measured. As described later, averaging is performed on the measurement results to remove the influence of Doppler displacement, and calibrated data are calculated. Then, by converting the three-dimensional data in a polar coordinate system formed by the laser beam's irradiation direction and the measured distances into three-dimensional data in an orthogonal coordinate system, three-dimensional measurement data representing the three-dimensional shape of wall 20A are obtained. In this example, three-dimensional measurement data (point group data) for multiple measurement points are obtained as three-dimensional measurement data.

[0086] [FSF type laser device]

[0087] Figure 3 This is a diagram showing the structure of the three-dimensional measuring device 10. The three-dimensional measuring device 10 uses an FSF (Frequency Shifted Feedback) laser device as a type of FMCW (Frequency Shifted Feedback) laser device, and includes a laser source 11 that outputs a frequency shifted feedback laser beam (FSF laser beam), a control unit 13 for the laser source 11, a laser scanner 15, and an encoder 17. The laser source 11 includes a laser medium, a mirror, an AOM (Acousto-Optic Modulator), etc., but as described in Japanese Patent Application Publication No. 2021-096383, an optical SSB modulator (SSB: Single Side Band) can be used as the frequency shifter.

[0088] [Mirror-based rotation scanning]

[0089] The laser scanner 15 scans the wall surface 20A (object) (two-dimensional scan) in the main scanning direction and the sub-scanning direction using a laser beam output from the laser source 11. Figure 4 This is a diagram illustrating an example of this two-dimensional scanning. For example... Figure 4As shown, the laser scanner 15 changes the direction of the laser beam (based on the reflection direction of the laser beam from the polygonal reflector 15A) in both the θ direction (main scanning direction) and the φ direction (sub-scanning direction) by rotating the polygonal reflector 15A (an example of a scanning direction changing component) on both axes via a motor 15B. Additionally, the laser scanner 15 includes a light receiver (not shown) to receive the laser beam reflected by the wall surface 20A.

[0090] In this two-dimensional scan, for example, after scanning in both the θ and φ directions in the positive direction (first direction) to obtain the first scan data (first measurement), scanning in both the θ and φ directions in the opposite direction (second direction) to obtain the second scan data (second measurement).

[0091] Figure 5 This is another example of a two-dimensional scan. In Figure 5 In the example shown, the one-way mirror 15C (another example of a tilting mirror; a scanning direction changing component) is rotated in the forward (first direction) or reverse (second direction) direction by the motor 15B, thereby changing the illumination direction of the laser beam output from the laser source 11. In this manner, when the tilt angle of the one-way mirror 15C can be changed about two axes, it is similar to... Figure 4 Similarly, the above examples can perform both forward and reverse scanning. Furthermore, even when the tilt angle of the one-way mirror 15C can only be changed around one axis (e.g., the φ direction), the entire wall surface 20A can be scanned by repeatedly performing one-dimensional scanning based on the travel or movement of the trolley 18.

[0092] [Acquisition of data regarding distance, speed, and direction]

[0093] Furthermore, the three-dimensional measuring device 10 includes an encoder 17 (angle detector) for detecting the rotation angle of the aforementioned reflector. The data processing device 14 (or measuring device 100) can calculate the irradiation direction (main scanning direction and sub-scanning direction) of the laser beam based on the output of the encoder 17, and can calculate the scanning speed (which can be a rectangular coordinate system or a polar coordinate system) based on the change in the irradiation direction and the measured distance. Thus, the data processing device 14 (or measuring device 100) can obtain the data by establishing a correlation between the measured distance (first distance, second distance), the scanning speed (first speed, second speed), and the scanning direction (main scanning direction, sub-scanning direction) for each measuring point on the wall 20A. In addition, since the three-dimensional position can be calculated based on the distance and direction to the measuring point, obtaining the data by establishing a correlation between distance, direction, and speed is equivalent to obtaining the data by establishing a correlation between three-dimensional position and speed.

[0094] [Example of measurement conditions]

[0095] The three-dimensional measuring device 10 can be used to measure minute irregularities (three-dimensional shapes) of the wall surface 20A, for example, under the following conditions.

[0096] • Measurement accuracy: 50 μm

[0097] • Measurement distance: 2~7m

[0098] • Measurement speed: 10m² (based on area) 2 / Second

[0099] Furthermore, the scanning speed of the laser beam itself is, for example, around 4000 rpm, but when the scanning direction is reversed (after a forward scan, it turns back to perform a reverse scan), the scanning speed is, for example, around 60 rpm. Also, the 3D measuring device 10 acquires 3D data of the wall 20A at constant intervals, for example, as the trolley 18 moves, but preferably acquires the 3D data in a manner where the measurement areas of the 3D data acquired at each interval partially overlap. This is for panoramic synthesis of the 3D data acquired at each interval.

[0100] The three-dimensional measuring device 10 can achieve the above-mentioned measurement accuracy by using a LiDAR configured in the FSF mode (an example of the FMCW mode).

[0101] Furthermore, the measurement accuracy and other conditions for the three-dimensional measurement data required in this invention are not limited to the examples described above, and the three-dimensional measurement device is not limited to an FSF-type LiDAR; various devices can be used. For example, in addition to FSF laser beams, DFB semiconductor lasers (DFB: Distributed Feedback), Fabry-Perot type semiconductor lasers, surface-emitting semiconductor lasers, etc., can also be used to generate FMCW-type laser beams. For example, if the drive current waveform of the semiconductor laser is controlled by a sawtooth wave or a triangular wave, the frequency changes according to the change in current, thus operating as a frequency-modulated continuous wave laser.

[0102] Preferably, the three-dimensional shape of the wall 20A is measured using the three-dimensional measuring device 10 at the start of tunnel measurement (construction) and during periodic inspections after construction. The three-dimensional measurement data can be recorded simultaneously at the start of measurement and during periodic inspections in the recording device 160 within the data processing device 14 and / or an external recording device. Design information (CAD data, etc.) of the tunnel 20 (object) can be recorded in the recording device 160 and / or the external recording device. As detailed later, this design information or past measurement results (pre-acquired measurements of the three-dimensional shape) can be used for the extraction of potential damage areas.

[0103] [Hardware structure of the measuring device]

[0104] Figure 6This is a diagram showing the hardware structure of the measuring device 100 (measuring apparatus). For example... Figure 6 As shown, the measuring device 100 functions as the data processing unit (processor unit) of the measuring system 1, and may be composed of, for example, a personal computer or workstation. The measuring device 100 includes a processor 110, a memory 120, a display device 130 (output device), an input / output interface 140, an operation unit 150, and a recording device 160 (output device). This measuring device 100 can function as... Figures 1-3 The data processing device 14 shown is programmed into a function.

[0105] The processor 110 (processor) consists of a CPU (Central Processing Unit) and other components, centrally controlling the various parts of the measuring device 100 and the measuring system 1, and is capable of executing distance measurement programs, distance calibration programs, shape measurement programs, damage evaluation programs, etc. Furthermore, details regarding the various processing based on the processor 110 will be described later.

[0106] The memory 120 includes flash memory, ROM (Read-only Memory), and RAM (Random Access Memory), etc. Flash memory and ROM are non-volatile memories (tangible and non-temporary recording media) that store operating systems, various programs including the measurement program involved in this invention, etc.

[0107] RAM functions as the working area for processing based on processor 110. It also stores various programs and three-dimensional measurement data of the surface of wall 20A (object, building) in temporary storage memory and the like. Furthermore, processor 110 may have a portion of memory 120 (RAM) built into it.

[0108] In addition to displaying the operation screen of the measuring device 100, the display device 130 can also display measurement results calculated by the measuring device 100 or graphs, charts, and images of building surface features created based on these results. The display device 130 also serves as part of the GUI (Graphical User Interface) when receiving user input (such as specifying points of interest on the building surface) via the operation unit 150. Alternatively, the display device 130 can be configured as a touch panel type device, and user operations can be received from this device.

[0109] The input / output interface 140 includes a connection part for connecting to external devices and a communication part for connecting to a network. As the connection part for connecting to external devices, USB (Universal Serial Bus) and HDMI (High-Definition Multimedia Interface) (HDMI is a registered trademark) can be used. The measuring device 100 can acquire the scan data required for measurement from external devices (other systems or recording devices) or recording media located on the Internet or in the cloud via this input / output interface 140.

[0110] The measuring device 100 can also be configured as a device independent of the data processing device 14. In this case, the processor 110 acquires three-dimensional measurement data of the building surface from the data processing device 14 via the input / output interface 140, or, if the three-dimensional measurement data is stored in a database in the cloud, it acquires the three-dimensional measurement data of the building surface from the cloud via the input / output interface 140. Furthermore, the processor 110 can record the acquired three-dimensional measurement data in the memory 120 or the recording device 160.

[0111] The operation unit 150 includes devices such as a mouse or keyboard, and functions as part of a GUI that uses the display screen of the display device 130 to receive instruction input based on user operation.

[0112] The recording device 160 comprises a non-temporary, tangible recording medium such as flash memory, hard disk, or optical-magnetic recording device, and its control unit. It stores three-dimensional measurement data (pre-acquired three-dimensional shape measurement results) of the building surface measured by the three-dimensional measuring device 10 at the start of building measurement and during periodic inspections, along with information indicating the measurement date and time. Design information (CAD data, etc.) of the three-dimensional shape of the tunnel 20 (object) can be recorded in the recording device 160. Furthermore, the recording device 160 can record various data required for processing (data selection methods, etc., described later), measurement results at each measurement point (first / second scan data, etc.), and data processing results (calibrated data, three-dimensional shape measurement results, damage candidate areas, etc.).

[0113] [Processing of Measurement Methods]

[0114] Next, the measurement method in the measurement system 1 with the above structure will be described. Figure 7 , 8This is a flowchart illustrating the processing of a measurement method as an embodiment of the present invention. Furthermore, the following description addresses the case where the measuring device 100 is programmed as a function of the data processing device 14 and the processing is primarily performed by the processor 110 (processor). Additionally, if the measuring device 100 is a separate device from the data processing device 14, the following processing can be shared between the data processing device 14 and the measuring device 100.

[0115] [Setting processing conditions]

[0116] The processor 110 sets the processing conditions for the measurement (step S100). These processing conditions may include scanning conditions for a new scan (scan range, spacing, laser beam illumination pattern, etc.). Alternatively, when measuring using pre-acquired data, the processing conditions may include specifying the data to be processed. Furthermore, the processing conditions may include specifying a method (described later) for selecting points from the measurement point group as objects for averaging. The processor 110 can set the processing conditions based on user operations via the operation unit 150, or it may set conditions determined independently of user operations. Additionally, some conditions, such as the method for selecting object points, may be performed in the processing described below (e.g., in step S130).

[0117] [Acquisition of scanned data]

[0118] Processor 110 acquires first scan data and second scan data (steps S110, S120). The first scan data includes the distance from laser scanner 15 to the measured portion of the wall surface 20A (object) obtained by scanning the measured portion of the wall surface 20A (object) along a first direction using laser scanner 15 (laser scanner), i.e., a first distance. The second scan data includes the distance from laser scanner 15 to the measured portion of the wall surface 20A obtained by scanning the measured portion of the wall surface 20A along a second direction using laser scanner 15, i.e., a second distance. As described above, processor 110 can perform a new scan to acquire the first and second scan data, or it can acquire data pre-recorded in a recording device such as recording device 160.

[0119] Figure 9 This diagram illustrates the calibration process using both clockwise and counterclockwise measurement results. Figure 9 Part (a) is a diagram showing the scanning status at a certain travel position (measurement location) in tunnel 20. Figure 9Part (b) is a diagram illustrating the state of obtaining calibration results by acquiring scan data (measurement results) with clockwise (positive) as the first direction and counterclockwise (opposite to clockwise) as the second direction. However, the scanning method is not limited to this example, as long as the first and second directions are different. Even if the second direction is different from completely counterclockwise (not completely opposite to the first direction), it can be treated as "completely counterclockwise (completely opposite to the first direction)" depending on the allowable calibration accuracy.

[0120] Figure 10 This is a graph showing the data acquired at each measurement point through scanning. Figure 10 In the example shown, for the i-th (i is an integer greater than or equal to 1) light spot (measurement point), the distance L will be... i Angle of elevation Θ i Azimuth Φ i Establish a connection to obtain (the first scan data, the second scan data). Additionally, distance L i The distance from the laser scanner 15 to the i-th spot (the measured part on the wall 20A) is the first distance in the case of the first scan and the second distance in the case of the second scan.

[0121] The processor 110 acquires this data in the first direction scan and the second direction scan, respectively. Furthermore, the measurement points for which data is acquired through the first direction scan and the second direction scan are collectively referred to as the first measurement point group and the second measurement point group, respectively.

[0122] The processor 110 can obtain the rates of change (first velocity, second velocity) of (distance, elevation angle, azimuth angle) for each measurement point in the first and second measurement point groups by establishing a correlation. Furthermore, (distance, elevation angle, azimuth angle) are equivalent to three-dimensional coordinates (x, y, z), and the rates of change of (distance, elevation angle, azimuth angle) are equivalent to three-dimensional velocities (Vx, Vy, Vz). Moreover, the processor 110 can calculate the line-of-sight velocity V at each measurement point based on these data. r and tangential velocity V t .

[0123] [Selection of measurement point pairings]

[0124] The processor 110 selects the pair of measurement points to be calibrated (step S130). This selection can be performed, for example, by the following methods. The processor 110 can determine which method to use based on the user's operation via the operation unit 150, or it can determine this independently of the user's operation. Furthermore, this determination can be performed in step S130, or it can be performed in step S100 as described above.

[0125] (Choose Method 1)

[0126] Processor 110 performs averaging on all pairs of points where the difference in distance between the first and second points is less than or equal to a reference value. Considering that pairs where the distance difference is less than the reference value are likely corresponding points (points that should have been measured as the same point), this type of pairing is selected in selection method 1. Furthermore, the "reference value" is the reference value for pairing selection and can be a value different from the "threshold" described below.

[0127] (Choose Method 2)

[0128] The processor 110 averages the points (first points) in the first measurement point group and the pairs of one or more second points selected from the second measurement point group in order of proximity to the first point. In selection method 2, the second points are thus selected with the first point as a reference.

[0129] (Choose method 3)

[0130] Processor 110 performs averaging on the second point and the pairs of one or more first points selected from the first measurement point group in order of proximity to the second point. In selection method 3, the first point is selected based on the second point, as opposed to selection method 2.

[0131] [Calibration corresponding to the distance between measurement points]

[0132] In the first embodiment, as described below, calibration (averaging) is performed corresponding to the distance between the selected measurement points (the distance between the first measurement point and the second measurement point). That is, if the measurement points are close to each other, averaging is performed without using speed data; if the distance is far, averaging is performed using speed data. This is because as long as the measurement points are close to each other, the calibration accuracy is good even without using speed data. Furthermore, this process allows for rapid calibration. However, the averaging process in this invention is not limited to this method; high-precision calibration can also be performed by averaging all paired speed data.

[0133] Specifically, the processor 110 determines whether the distance between the measurement points is above a threshold (step S140). If the distance is close (if it is less than the threshold, then "no" in step S140), then proceed to step S155 without using the speed data for averaging.

[0134] [Averaging process when the distance between measurement points is less than a threshold]

[0135] The position of the first measurement point is set to (x1, y1, z1), and the position of the second measurement point is set to (x2, y2, z2). The processor 110 can use the following equation (1) to calculate the distance L from the above (distance L) i Angle of elevation Θ i Azimuth Φ i Calculate these positions.

[0136] [Formula 1]

[0137] x i =L i ×sinΘ i ×cosΦ i

[0138] y i =L i ×sinΘ i ×sinΦ i

[0139] z i =L i ×cosΘ i ……(1)

[0140] Then, the processor 110 calculates the calibrated position (x, y, z) by averaging the positions of the first and second measurement points using the following formula (2) (one method of averaging) (step S155). This calibrated position corresponds to the calibrated data.

[0141] [Formula 2]

[0142] x = (x1 + x2) / 2

[0143] y = (y1 + y2) / 2

[0144] z=(z1+z2) / 2……(2)

[0145] [Averaging process when the distance between measurement points is above a threshold]

[0146] If the distance between the measurement points is above a threshold ("Yes" in step S140), the velocity data is averaged. Figure 11 This is a conceptual diagram representing a state that has undergone averaging processing of velocity data. Figure 11 In the middle, by scanning in a clockwise direction (the first scan in the first direction) at the measurement point SP 11 ~SP 17 Data is acquired and measured at point SP via a counter-clockwise scan (a second scan in the opposite direction to the first direction). 21 ~SP 26Data acquisition. In the first embodiment, the points whose positions are divided internally by the ratio of the absolute values ​​of the velocities in each measurement point are set as the calibrated positions (a group of points represented by the reference symbol SPt).

[0147] The following section provides a detailed explanation of the averaging process used for velocity data. For simplicity, the explanation is presented in two dimensions, but the same process can be performed in three dimensions.

[0148] Figure 12 This is a graph showing the relationship between the velocity in the line-of-sight direction and the velocity in the tangential direction. In Figure 12 In this context, subscript "1" indicates a forward scan (clockwise, the first scan), and subscript "2" indicates a reverse scan (counterclockwise, the second scan). Additionally, angle θ is set to be measured counterclockwise from the x-axis towards the y-axis. In this case, if the angular velocities obtained by encoder 17 at measurement points P1 and P2 are set as ω1 and ω2, the tangential velocities obtained in the forward and reverse scans are represented by the following equation (3).

[0149] [Formula 3]

[0150] V t1 =r1×ω1

[0151] V t2 =r²×ω²……(3)

[0152] Here, we consider V1 and V t1 The angle formed by V2 and V t2 The angles formed are equal under the condition that "the positions of measurement points P1 and P2 are close enough", so the following equation (4) holds.

[0153] [Formula 4]

[0154] V r1 V r2 ≈V t1 V t2 ……(4)

[0155] That is, the values ​​of the velocity in the line of sight direction and the velocity in the tangential direction are different, but if the ratio of the two is taken, they are equal.

[0156] Figure 13 This is a diagram representing the internal division of the position based on the ratio of the absolute values ​​of velocities. Regarding Doppler displacement, in the beat frequency region, it can be expressed as Δf = 2 × V. r / λ, in the distance region, can be expressed as Δr=c×Δf / (2T) (λ: wavelength of the laser beam, T: frequency modulation rate). Therefore, when the true values ​​of the distances at measurement points P1 and P2 are set as r1 and r2 respectively, the measured values ​​are obtained as r1+Δr1 and r2+Δr2 respectively. Furthermore, according to the above formula for Doppler displacement, it becomes Δr1=V r1 ×c / (λτ), Δr2=V r2 ×c / (λτ). Additionally, Δr1 and Δr2 represent the effects caused by the Doppler displacement, and "c / (λT)" is a constant determined by the structure of the laser scanner.

[0157] [Inner division of position based on the ratio of absolute velocities]

[0158] Based on the above, if the true value of the position of the measurement point represented by orthogonal coordinates is set as (x, y), and the measured value is set as (x', y'), then the relationship between the true value and the measured value of measurement points P1 and P2 is represented by the following equations (5) and (6).

[0159] [Formula 5]

[0160] x'1=x1+V r1 ×cosθ1×{c / (λτ)}

[0161] y'1=y1+V r1 ×sinθ1×{c / (λτ)}……(5)

[0162] [Formula 6]

[0163] x'2=x2+V r2 ×cosθ2×{c / (λτ)}

[0164] y'2=y2+V r2 ×sinθ2×{c / (λτ)}……(6)

[0165] In equations (5) and (6), the second term represents the effect of Doppler displacement.

[0166] By using these measurements (x'1, y'1) and (x'2, y'2) with V r The ratio of the absolute values ​​is divided internally, as shown in Equation (7) below, which allows the calculation of the position of the measurement point (calibrated data) excluding the influence of Doppler displacement. In addition, in Equation (7), Δθ (the difference between θ1 and θ2) is sufficiently small and its first-order insignificance can be ignored.

[0167] [Formula 7]

[0168] x t =(|V r2 |×x'1+|Vr1 |×x'2) / (|V r1 |+|V r2 |)

[0169] ≈(|V r2 |×x1+|V r1 |×x2) / (|V r1 |+|V r2 |)

[0170] y t =(|V r2 |×y'1+|V r1 |×y'2) / (|V r1 |+|V r2 |)

[0171] ≈(|V r2 |×y1+|V r1 |×y2) / (|V r1 |+V r2 |)

[0172] ……(7)

[0173] In addition, in equation (7), the inner ratio is |V r1 |:|V r2 However, it is also possible to divide the inner part using other ratios. For example, when Δθ cannot be ignored, the ratio of the inner parts with respect to x can be considered as |V|. r1 |cosθ1:|V r2 |cosθ2, weighted by cosθ, uses the inner fraction of y as |V r1 |sinθ1:|V r2 |sinθ2 is weighted by sinθ. Furthermore, the same equation holds even if orthogonal coordinates are replaced with polar coordinates (r, θ).

[0174] Through this process, the position of the measurement point (the calibrated position of the measured part; calibrated data) can be obtained by accurately calibrating the influence of Doppler displacement. Then, by repeating the process of steps S130 to S155 (until "yes" is achieved in step S160), position data (calibrated data) of multiple wall surfaces 20A (objects) can be obtained, and these data can be used to measure the three-dimensional shape of the wall surface 20A (step S170).

[0175] [Damage Candidate Region Extraction]

[0176] The processor 110 can calculate the design information of the three-dimensional shape of the wall surface 20A (object) of the measured three-dimensional shape and / or the variation from the measurement results of the three-dimensional shape obtained in advance, and extract the area where the variation exceeds the reference as a damage candidate area (step S180). The "design information" can be, for example, three-dimensional data generated from CAD data, and the "pre-obtained measurement results" can be past measurement results. Furthermore, the "reference" is, for example, a threshold for variation, and a threshold set by the user can also be used. Furthermore, the processor 110 can display the extracted damage candidate areas on the display device 130 (display device, output device) and / or record them on the recording device 160 (recording device, output device).

[0177] Figure 14 This is a graph representing the display status of candidate damage areas. Specifically, it is an example of displaying the magnitude of changes in the three-dimensional shape (the aforementioned design information of the three-dimensional shape and / or changes from the measurement results of the three-dimensional shape obtained in advance). In the graph, the intensity of the color indicates the magnitude of the change. The darker the color, the greater the change; the changes in regions 634 and 636 are greater than the changes in regions 630 and 632. In such a graph, the processor 110 can establish a correlation (establish a correspondence) by overlaying the measured magnitude of the change with the image or design information of the wall surface 20A. In addition, besides color intensity, the processor 110 can also display the magnitude of the change using chroma instead of color intensity, and can also combine color intensity with characters, numbers, graphics, symbols, charts, etc., for display.

[0178] In measurement system 1, damage can be accurately measured or evaluated in the above-mentioned candidate damage areas using a certain measurement method (e.g., laser interferometer, non-contact acoustic vibration, image processing, etc.).

[0179] The processor 110 can display the measurement results of the three-dimensional shape and the evaluation results of the damage in a time series manner on the display device 130 and / or record them on the recording device 160 through graphs or curves. It can also perform predictions based on past measurement results (step S190) and output (display, record, etc.) the results. The processor 110 can extrapolate past measurement results using linear or nonlinear functions to predict shape changes or damage, or it can use predictors built through machine learning or predictive models built through other methods to make predictions. Such predictions can be reflected in the planning of evaluation, inspection, and repair of damage such as buoyancy.

[0180] The embodiments of the present invention have been described above, but the present invention is not limited to the above-described manner and can be modified in various ways.

[0181] Symbol Explanation

[0182] 1-Measurement system, 10-3D measurement device, 11-Laser light source, 12-Tripod, 13-Control unit, 14-Data processing unit, 15-Laser scanner, 15A-Polygonal reflector, 15B-Motor, 15C-One-way mirror, 16-Power supply unit, 17-Encoder, 18-Cart, 20-Tunnel, 20A-Wall, 100-Measurement device, 110-Processor, 120-Memory, 130-Display device, 140-Input / output interface, 150-Operation unit, 160-Recording device, 630-Area, 632-Area, 634-Area, 636-Area, P1-Measurement point, P2-Measurement point.

Claims

1. A measuring device comprising a processor, wherein, The processor performs the following processing: Acquire first scan data, the first scan data including information representing a first distance, the first distance being the distance from the laser scanner to the measured part obtained by scanning the measured part of the object along a first direction with a laser scanner; Acquire second scan data, the second scan data including information representing a second distance, the second distance being the distance from the laser scanner to the measured portion obtained by scanning the measured portion of the object in a second direction different from the first direction; and By averaging the first and second scan data, calibrated data that removes the influence of Doppler shift from the first and second scan data is calculated.

2. The measuring device according to claim 1, wherein, The processor performs the averaging process corresponding to the distance between the first measurement point where the first scan data was acquired and the second measurement point where the second scan data was acquired.

3. The measuring device according to claim 2, wherein, In the averaging process, the processor averages the positions of the first measurement point and the second measurement point.

4. The measuring device according to claim 1 or 2, wherein, The processor performs the following processing: Each measurement point in the first measurement point group used to acquire the first scan data is acquired by including the first speed, which is the first speed, in the first scan data. Regarding each measurement point in the second measurement point group used to acquire the second scan data, the second speed, which is the scanning speed, is included in the second scan data. The averaging process is performed on the first scan data and the second scan data using the first speed and the second speed.

5. The measuring device according to claim 4, wherein, The processor in the averaging process The calibrated data is calculated by dividing the positions of the points selected from the first measurement point group (i.e., the first point) and the points selected from the second measurement point group (i.e., the second point) by the ratio of the absolute value of the first velocity at the first point to the absolute value of the second velocity at the second point.

6. The measuring device according to claim 5, wherein, The processor sets the internal ratio to 1:1 to perform the averaging process.

7. The measuring device according to claim 5, wherein, The processor performs the averaging process on all pairs of points where the distance difference between the first point and the second point is below a reference value.

8. The measuring device according to claim 5, wherein, The processor performs the averaging process on the points in the first measurement point group and the pairs of one or more of the second points selected from the second measurement point group in order of proximity to the first point.

9. The measuring device according to claim 5, wherein, The processor performs the averaging process on the second point and the pairing of one or more of the first points selected from the first measurement point group in order of proximity to the second point.

10. The measuring device according to any one of claims 1 to 3, wherein, The processor uses multiple sets of calibrated data to measure the three-dimensional shape of the object.

11. The measuring device according to claim 10, wherein, The processor performs the following processing: extracting a damage candidate region of the object based on the measured three-dimensional shape; and outputting information representing the extracted damage candidate region to an output device.

12. The measuring device according to claim 11, wherein, The processor extracts the design information of the three-dimensional shape of the object and / or the regions where the variation from the pre-acquired measurement results of the three-dimensional shape exceeds the baseline as the damage candidate regions.

13. A measurement system comprising: The measuring device according to any one of claims 1 to 3; and The laser scanner.

14. The measurement system according to claim 13, wherein, The laser scanner is a laser scanner that uses a laser beam in a frequency-modulated continuous wave manner.

15. The measurement system according to claim 14, wherein, The laser scanner is a laser scanner that uses a frequency-displacement feedback type laser beam.

16. A measurement method, which is performed by a measuring device having a processor, wherein, The processor performs the following processing: Acquire first scan data, the first scan data including information representing a first distance, the first distance being the distance from the laser scanner to the measured part obtained by scanning the measured part of the object along a first direction with a laser scanner; Acquire second scan data, the second scan data including information representing a second distance, the second distance being the distance from the laser scanner to the measured portion obtained by scanning the measured portion of the object in a second direction different from the first direction; and By averaging the first and second scan data, calibrated data that removes the influence of Doppler shift from the first and second scan data is calculated.

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