Measurement device, measurement system and measurement method

Abstract

One embodiment of the technology of the present invention provides a measurement device, a measurement system, and a measurement method capable of calibrating Doppler displacement with high accuracy. In a measurement device according to one embodiment of the present invention, a processor performs: a process for acquiring first scan data including information indicating a first distance obtained by scanning a portion to be measured of an object in a first direction with a laser scanner, the first distance being a distance from the laser scanner to the portion to be measured; acquiring second scan data including information indicating a second distance, the second distance being a distance from the laser scanner to a portion to be measured, the second distance being obtained by scanning the portion to be measured of the object in a second direction different from the first direction by the laser scanner; and performing an averaging process on the first scan data and the second scan data to calculate post-calibration data in which the influence of Doppler shift in the first scan data and the second scan data is removed.

Description

TECHNICAL FIELD

[0001] The present application relates to a measurement device, a measurement system, and a measurement method, and particularly relates to a technique for measuring an object using a laser beam. BACKGROUND

[0002] In recent years, inspection or maintenance management (grasping the state of the structure, repair according to the state, and the like) of so-called "social infrastructure structures" such as roads, bridges, tunnels, dams, buildings, and the like, and specifically, grasping the presence or degree of defects (or damages) such as cracks or "heaving", peeling, and the like, has become a major social problem. In addition, "infra" is an abbreviation of "infrastructure".

[0003] In the past, a worker confirmed defects of an object by visual observation or tapping. However, such work requires time and effort, and sometimes it is difficult to approach the inspection object.

[0004] Therefore, in view of this situation, a technique for measuring an object in a non-contact manner using a laser beam is being studied, and defects are detected based on measurement of a slight unevenness (three-dimensional shape). In such measurement, when a social infrastructure structure is taken as an object, high-speed scanning and high-precision detection are required depending on the kind and size of the object, and the like, but there is a problem that if the scanner moves relative to the measurement object, the measurement accuracy (ranging accuracy) decreases due to Doppler shift.

[0005] As a technique for coping with such a problem, for example, Patent Literature 1 is known. In Patent Literature 1, a technique for calibrating Doppler shift in a case where a measurement head is fixed to a moving measurement object is described. Specifically, a sample of a measured object is caused to move at a plurality of speeds, and the difference between these moving speeds is calculated as a calibration speed, and further, the difference in the frequency of reflected light at these moving speeds is calculated as a frequency shift amount.

[0006] Prior Art Documents

[0007] Patent Literature

[0008] Patent Literature 1: Japanese Patent Application Publication No. 2020-046368 SUMMARY

[0009] Technical Problem to be Solved by the Invention

[0010] In the case where measurement is performed using a laser beam, depending on the kind or size of the measurement object (for example, in the case where the measurement object is a social infrastructure structure), it is sometimes difficult (in fact, impossible) to move or rotate the measurement object itself, in which case the measurement angle changes as the optical axis direction changes along with scanning. However, such a case is not considered in the above-described patent document 1. Also, depending on the measurement object, it is difficult to measure the angle in each of the obtained point groups as in patent document 1, in advance measurement in the entire measurement section. Also, depending on the measurement object, it is difficult to accurately aim at the same position for measurement for two measurements with changed speeds.

[0011] Thus, in the conventional technology, it is difficult to calibrate the Doppler shift accompanying a change in the scanning direction.

[0012] The present application was completed in view of such a situation, and aims to provide a measurement device, measurement system, and measurement method capable of calibrating a Doppler shift with high precision.

[0013] Means for solving the technical problem

[0014] To achieve the above object, a measurement device according to a first aspect of the present application includes a processor that performs the following processing: acquires first scanning data including information indicating a first distance from a laser scanner to a measured portion of an object scanned by the laser scanner in a first direction; acquires second scanning data including information indicating a second distance from the laser scanner to the measured portion of the object scanned by the laser scanner in a second direction different from the first direction; and calculates, by performing averaging processing on the first scanning data and the second scanning data, post-calibration data in which the influence of a Doppler shift in the first scanning data and the second scanning data is removed.

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

[0016] That is, the first and second scanning data are time-series data, and the measurement result includes a deviation from a true value based on the Doppler shift.

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

[0018] Therefore, if the first scanning data and the second scanning data are subjected to averaging processing, the influence of the Doppler shift can be canceled out.

[0019] In addition, in the first and each of the following modes, the first direction and the second direction can be opposite directions, but can not be completely opposite directions.

[0020] Thus, according to the measurement device related to the first mode, the Doppler shift can be calibrated with high precision.

[0021] In addition, in the first and each of the following modes, the first and second scan data can include distance data and scan direction data (for example, azimuth and elevation, or main scan direction and sub scan direction), or can include three-dimensional position data.

[0022] The distance and the scan direction and the three-dimensional position are equivalent information that can be converted to each other.

[0023] Also, the measurement device related to the first mode can be implemented, for example, as a processor portion (a portion that acquires and processes measurement data) of a measurement system, but is not limited to this mode.

[0024] The measurement device related to the second mode, in the first mode, the processor performs an averaging process corresponding to a distance between a first measurement point at which the first scan data is acquired and a second measurement point at which the second scan data is acquired.

[0025] For example, different averaging processes can be performed in a case where the distance between the first measurement point and the second measurement point is short and in a case where the distance is long.

[0026] The measurement device related to the third mode, in the second mode, the processor averages a position of the first measurement point and a position of the second measurement point in the averaging process.

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

[0028] The measurement device related to the fourth mode, in the first or second mode, the processor performs the following process: with respect to each measurement point of a first measurement point group at which the first scan data is acquired, a first velocity as a scan velocity is included in the first scan data to be acquired, with respect to each measurement point of a second measurement point group at which the second scan data is acquired, a second velocity as a scan velocity is included in the second scan data to be acquired, and the first scan data and the second scan data are subjected to an averaging process using the first velocity and the second velocity.

[0029] The measurement device related to the fifth mode, in the fourth mode, the processor, in the averaging process, calculates a position in which a position of a first point selected from the first measurement point group and a position of a second point selected from the second measurement point group are divided by a ratio of an absolute value of the first velocity in the first point to an absolute value of the second velocity in the second point as post-calibration data.

[0030] The measurement device according to the sixth aspect is the measurement device according to the fifth aspect, in which the processor performs the averaging process with the inner division ratio set to 1:1.

[0031] The sixth aspect specifies a specific method of the averaging process.

[0032] The measurement device according to the seventh aspect is the measurement device according to the fifth or sixth aspect, in which the processor performs the averaging process on all pairs of points that are paired with the first point and the second point and in which the distance difference between the first point and the second point is equal to or less than a reference value.

[0033] The seventh aspect specifies a selection method of data that is a target of the averaging process.

[0034] The measurement device according to the eighth aspect is the measurement device according to the fifth or sixth aspect, in which the processor performs the averaging process on pairs of points that are paired with a point in the first group of measurement points and one or more second points selected from the second group of measurement points in order of proximity to the first point.

[0035] The eighth aspect specifies another selection method of data that is a target of the averaging process.

[0036] The measurement device according to the ninth aspect is the measurement device according to the fifth or sixth aspect, in which the processor performs the averaging process on pairs of points that are paired with a second point and one or more first points selected from the first group of measurement points in order of proximity to the second point.

[0037] The ninth aspect specifies still another selection method of data that is a target of the averaging process.

[0038] The measurement device according to the tenth aspect is the measurement device according to any one of the first to ninth aspects, in which the processor can measure a three-dimensional shape of the object using a plurality of pieces of calibrated data.

[0039] Further, the processor can evaluate a damage (defect) such as lifting or peeling based on the measurement result.

[0040] The measurement device according to the eleventh aspect is the measurement device according to the tenth aspect, in which the processor extracts a damage candidate region of the object based on the measured three-dimensional shape, and outputs information indicating the extracted damage candidate region to an output device.

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

[0042] The measurement device according to the twelfth aspect is the measurement device according to the eleventh aspect, in which the processor performs a process of extracting design information of the three-dimensional shape of the object and / or a region in which a variation from a measurement result of a three-dimensional shape acquired in advance exceeds a reference as a damage candidate region.

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

[0044] Also, for example, the determined threshold value can be set as a "reference".

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

[0046] In the measurement system according to the 13th aspect, by including the measurement device according to any one of the 1st to 12th aspects, the Doppler shift can be calibrated with high precision.

[0047] In the 13th aspect, the laser scanner preferably outputs information indicating a distance and information indicating a direction of laser irradiation in association with each other.

[0048] The measurement device can utilize the output.

[0049] A measurement system according to a 14th aspect includes the measurement system according to the 13th aspect, in which the laser scanner is a laser scanner using a frequency-modulated continuous wave laser beam.

[0050] A "frequency-modulated continuous wave laser" (sometimes referred to as "FMCW laser") is a laser beam that transmits a frequency-modulated continuous wave, and can calculate a distance to an object based on a frequency difference (beat frequency) between a transmitted wave and a reflected wave.

[0051] In measurement using a frequency-modulated continuous wave laser beam, a distance resolution is determined based on a "measurement resolution per unit time of a frequency change amount (frequency modulation rate) and a beat frequency".

[0052] A measurement system according to a 15th aspect includes the measurement system according to the 14th aspect, in which the laser scanner is a laser scanner using a frequency-shifted feedback laser beam.

[0053] A "frequency-shifted feedback laser" (hereinafter, sometimes referred to as "FSF laser") is a type of frequency-modulated continuous wave laser.

[0054] To achieve the above object, a measurement method according to a 16th aspect is executed by a measurement device provided with a processor, and the processor performs the following processing: acquires first scan data including information indicating a first distance, the first distance being a distance from the laser scanner to the measured portion 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, the second distance being a 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 with the laser scanner; and calculates post-calibration data in which the influence of Doppler shift in the first scan data and the second scan data is removed, by performing averaging processing on the first scan data and the second scan data.

[0055] According to the 16th aspect, as with the 1st aspect, it is possible to calibrate Doppler shift with high precision.

[0056] The measurement method according to the 16th aspect can have the same structure as the 2nd to 12th aspects.

[0057] Further, a non-transitory and tangible recording medium (e.g., various optical magnetic recording devices or semiconductor memories) that records a program for causing a measurement device provided with a processor to execute the measurement method of these aspects and a computer-readable code of these programs can also be cited as aspects of the present application.

[0058] Note that the "non-transitory and tangible recording medium" does not include a non-tangible recording medium such as a carrier wave or a propagated signal itself.

[0059] Effects of Invention

[0060] As explained above, according to the measurement device, the measurement system, and the measurement method of the present application, it is possible to calibrate Doppler shift with high precision. BRIEF DESCRIPTION OF DRAWINGS

[0061] Figure 1 is a diagram showing the structure of the measurement system according to the 1st aspect.

[0062] Figure 2 is an appearance view of the three-dimensional measurement device according to the 1st aspect.

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

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

[0065] Figure 5 is a diagram showing another example of two-dimensional scanning.

[0066] Figure 6 is a diagram showing a hardware structure of a data processing apparatus.

[0067] Figure 7 is a flowchart showing a process of a measurement method (1 / 2).

[0068] Figure 8 is a flowchart showing a process of a measurement method (2 / 2).

[0069] Figure 9 is a diagram showing a case where calibration is performed using clockwise and counterclockwise measurement results.

[0070] Figure 10 is a diagram showing a state where data is acquired at each measurement point by scanning.

[0071] Figure 11 is a diagram showing a case where distance calibration is performed using velocity data.

[0072] Figure 12 is a diagram showing a line-of-sight direction velocity and a tangent direction velocity in a case where scanning directions are different.

[0073] Figure 13 is a diagram showing a case where an influence of Doppler shift is canceled by reverse scanning.

[0074] Figure 14 is a diagram showing an output example of a lesion candidate region. DETAILED DESCRIPTION

[0075] [Influence of Doppler shift in measurement]

[0076] In measurement using a laser beam, as described above, it is difficult to aim at the same point and measure multiple times, and in a case where an asymmetrically shaped mirror is used in order to change the irradiation direction of the laser beam (see, for example, Patent Literature 1), the rotational velocity sometimes subtly changes depending on the rotational position. Due to this, the relative distance or the relative velocity to the measurement object changes during scanning, and sometimes the distance measurement accuracy (measurement accuracy) decreases due to the influence of Doppler shift. In response to this problem, depending on the kind or the size of the object, or the like, it is difficult to move the object as described in Patent Literature 1 or to scan or measure the same point at multiple velocities. Figure 4 Figure 5

[0077] ​​The present inventors have conducted intensive research in view of this situation, and have arrived at the idea that, in forward scanning and reverse scanning, the sign of the deviation of the Doppler shift from the true value should be opposite in the measurement data, and therefore, if the measurement results based on forward scanning and the measurement results based on reverse scanning are averaged, the influence of the Doppler shift is cancelled out, and the distance (three-dimensional shape) can be measured with high precision. Hereinafter, embodiments of the present application based on this idea will be described.

[0078] [First Embodiment]

[0079] A first embodiment of a measurement device, a measurement system, and a measurement method according to the present application will be described in detail.

[0080] Figure 1 is a diagram showing the structure of a measurement system according to the first embodiment. As shown in Figure 1 , the measurement system 1 (measurement system) is a system for measuring and inspecting a railway tunnel, and is provided with 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 measurement device 10 is a LiDAR (Light Detection And Ranging), and in particular, a frequency-modulated continuous wave (FMCW) LiDAR capable of distance measurement with an accuracy of several hundred μm, but the present application is not limited to the case where distance measurement data (three-dimensional measurement data) measured by the FMCW LiDAR is used. In addition, the three-dimensional measurement device 10 is mounted on a tripod 12, but can also be mounted on a trolley 18 that travels or moves on a track.

[0082] [Three-dimensional measurement device]

[0083] Figure 2 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. As shown in Figure 2 , the three-dimensional measurement device 10 is mounted on the trolley 18 that travels on a track, and measures the distance to a wall surface 20A (object, measured portion) of a tunnel 20 (object). On the trolley 18, in addition to the three-dimensional measurement device 10, a data processing device 14 (processor) and a power supply device 16 are mounted. The power supply device 16 supplies power to the three-dimensional measurement device 10 and the data processing device 14.

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

[0085] exist Figure 2 In the example shown, the three-dimensional measuring device 10 is Figure 2 The laser beam of the FSF method, which is one method of the FMCW method, is scanned at high speed in the left-right direction (main scanning direction) of the wall surface 20A shown in FIG. 2 , and the scanning line is moved in the up-down direction (sub-scanning direction) of the wall surface 20A. In this way, the laser scanner 15 (refer to FIG. 2 ) of the three-dimensional measuring device 10 is measured. Figure 3 ) to multiple measurement points on each scanning line of the laser beam. As described later, the measurement results are averaged to remove the influence of Doppler shift, and calibrated data is calculated. Then, by converting the three-dimensional data in the polar coordinate system, which is composed of the laser beam irradiation direction and the measured distance, into three-dimensional data in the orthogonal coordinate system, three-dimensional measurement data representing the three-dimensional shape of the wall surface 20A is obtained. In this example, three-dimensional measurement data (point group data) of multiple measurement points is obtained as the three-dimensional measurement data.

[0086] [FSF laser device]

[0087] Figure 3 This diagram shows the structure of a three-dimensional measuring device 10. The three-dimensional measuring device 10 uses an FSF (Frequency Shifted Feedback) laser device, a form of the FMCW method. It includes a laser light source 11 that outputs a frequency-shifted feedback laser beam (FSF laser beam), a control unit 13 for the laser light source 11, a laser scanner 15, and an encoder 17. The laser light source 11 includes a laser medium, a reflective mirror, an AOM (Acousto-Optic Modulator), and other components. However, as described in Japanese Patent Application Laid-Open No. 2021-096383, an optical SSB modulator (SSB) can be used as a frequency shifter.

[0088] [Scanning by Mirror Rotation]

[0089] The laser scanner 15 scans the wall surface 20A (object) in the main scanning direction and the sub-scanning direction using the laser beam output from the laser light source 11 (two-dimensional scanning). Figure 4 is a diagram showing an example of such a two-dimensional scan. Figure 4As shown, the laser scanner 15 changes the irradiation direction of the laser beam (the reflection direction of the laser beam based on the polygon mirror 15A) to the θ direction (the main scanning direction) and the φ direction (the sub scanning direction) by bi-axially rotating the polygon mirror 15A (an example of a scanning direction changing member) by the motor 15B. In addition, the laser scanner 15 has a light receiver not shown which receives the laser beam reflected by the wall surface 20A.

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

[0091] Figure 5 is a view showing another example of two-dimensional scanning. In Figure 5 In the example shown, the irradiation direction of the laser beam output from the laser light source 11 is changed by rotating the single mirror 15C (tilt mirror; another example of a scanning direction changing member) in the positive direction (first direction) or the negative direction (second direction) by the motor 15B. In this manner, when the tilt angle of the single mirror 15C can be changed around two axes, the entire wall surface 20A can be scanned by performing one-dimensional scanning repeatedly according to the travel or movement of the trolley 18, as in the above example of Figure 4 In the example shown, the irradiation direction of the laser beam output from the laser light source 11 is changed by rotating the single mirror 15C (tilt mirror; another example of a scanning direction changing member) in the positive direction (first direction) or the negative direction (second direction) by the motor 15B. In this manner, when the tilt angle of the single mirror 15C can be changed around two axes, the entire wall surface 20A can be scanned by performing one-dimensional scanning repeatedly according to the travel or movement of the trolley 18, as in the above example of

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

[0093] In addition, the three-dimensional measurement device 10 has an encoder 17 (angle detector) which detects the rotation angle of the above-described mirror. The data processing device 14 (or the measurement device 100) can calculate the irradiation direction of the laser beam (the main scanning direction and the sub scanning direction) from the output of the encoder 17, and can calculate the scanning speed (in a rectangular coordinate system or a polar coordinate system) from the change in the irradiation direction and the measured distance. Thus, the data processing device 14 (or the measurement device 100) can acquire the measured distance (first distance, second distance), the speed of scanning (first speed, second speed), and the direction of scanning (main scanning direction, sub scanning direction) in association with each other for each measurement point on the wall surface 20A. In addition, since the three-dimensional position can be calculated from the distance and the direction to the measurement point, the distance, the direction, and the speed are acquired in association with each other, which is equivalent to acquiring the three-dimensional position and the speed in association with each other.

[0094] [Example of measurement conditions]

[0095] The three-dimensional measurement device 10 can perform measurement of the minute unevenness shape (three-dimensional shape) of the wall surface 20A, for example, under the following conditions.

[0096] • Measurement accuracy: 50 μm

[0097] • Measurement distance: 2 to 7 m

[0098] • Measurement speed: 10 m2 / sec 2

[0099] In addition, the scanning speed of the laser beam itself is, for example, about 4000 rpm, but the scanning speed when the scanning direction is reciprocated (after forward scanning, the scanning is reversed to perform reverse scanning) is, for example, about 60 rpm. Also, the three-dimensional measurement device 10 acquires three-dimensional data of the wall surface 20A at constant intervals while the trolley 18 is moving, but preferably acquires three-dimensional data in a manner that the measurement regions of the three-dimensional data acquired at each interval are partially overlapped. This is to perform panoramic synthesis of the three-dimensional data acquired at each interval.

[0100] The three-dimensional measurement device 10 can achieve the above-described measurement accuracy and the like by the LiDAR configured in the FSF system (an example of the FMCW system).

[0101] In addition, the conditions such as the measurement accuracy of the three-dimensional measurement data required in the present application are not limited to the above-described examples, and the three-dimensional measurement device is not limited to the LiDAR of the FSF system, and various devices can be applied. For example, in addition to the FSF laser beam, a DFB semiconductor laser (DFB: Distributed Feedback), a Fabry-Perot semiconductor laser, a surface emitting semiconductor laser, or the like can be used to generate a laser beam of the FMCW system. For example, if the driving current waveform of the semiconductor laser is controlled by a sawtooth wave or a triangular wave, the frequency changes according to the change in the current, and thus the semiconductor laser operates as a frequency-modulated continuous wave laser.

[0102] It is preferable that the three-dimensional measurement device 10 measures the three-dimensional shape of the wall surface 20A at the start of measurement (construction) of the tunnel and at the time of periodic inspection after the construction. The three-dimensional measurement data can be recorded in the recording device 160 in the data processing device 14 and / or an external recording device at the start of measurement and at the time of periodic inspection. Design information (CAD data or the like) of the tunnel 20 (object) can be recorded in the recording device 160 and / or the external recording device. As described in detail later, such design information or past measurement results (measurement results of the three-dimensional shape acquired in advance) can be used for extraction of a damage candidate region.

[0103] [Hardware configuration of measurement device]

[0104] Figure 6 ​is a diagram showing a hardware structure of the measurement device 100 (measurement device). As shown in Figure 6 the measurement device 100 functions as a data processing portion (processor portion) of the measurement system 1, for example, constituted by a personal computer, a work station, or the like. The measurement device 100 is provided with a processor 110, a memory 120, a display device 130 (output device), an input / output interface 140, an operation portion 150, and a recording device 160 (output device). This measurement device 100 can be incorporated as one function of the data processing device 14 shown in Figures 1 to 3

[0105] The processor 110 (processor) is constituted by a CPU (Central Processing Unit) or the like, centrally controls each portion of the measurement device 100 and the measurement system 1, and can execute a distance measurement program, a distance calibration program, a shape measurement program, a damage evaluation program, and the like. In addition, the details of various processes based on the processor 110 will be described later.

[0106] The memory 120 includes a flash memory, a ROM (Read-only Memory), and a RAM (Random Access Memory), or the like. The flash memory and the ROM are nonvolatile memories (tangible and non-transitory recording media) that store an operating system, various programs including the measurement programs relating to the present application, and the like.

[0107] The RAM functions as a work area for processes based on the processor 110. Also, various programs stored in the memory or the like and three-dimensional measurement data of the surface of the wall surface 20A (object, building), or the like are temporarily stored. In addition, the processor 110 can have a part (RAM) of the memory 120 built in.

[0108] The display device 130 can display, in addition to an operation screen of the measurement device 100, a measurement result calculated by the measurement device 100 or a graph, a chart, a surface property image of a building, or the like made on the basis thereof. The display device 130 also functions as a part of a GUI (Graphical User Interface) when receiving an input (designation of a point of interest on the surface of the building, or the like) of a user via the operation portion 150. In addition, the display device 130 can be constituted by a touch panel type device, and receives an operation of a user by the device.

[0109] ​The input / output interface 140 includes a connection portion capable of connecting with an external device, a communication portion capable of connecting with a network, and the like. As the connection portion capable of connecting with an external device, a USB (Universal Serial Bus), an HDMI (High-Definition Multimedia Interface) (HDMI is a registered trademark), and the like can be applied. The measurement device 100 can acquire scan data and the like required for measurement from an external device (another system or a recording device) or a recording medium existing on the Internet or a cloud via the input / output interface 140.

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

[0111] The operation portion 150 includes a device such as a mouse or a keyboard, and functions as a part of a GUI that receives an instruction input based on a user operation using a display screen of the display device 130.

[0112] The recording device 160 is configured of a non-transitory and tangible recording medium such as a flash memory, a hard disk device, a magnetic-optical recording device, and a control portion thereof, and stores the three-dimensional measurement data of the surface of the building measured by the three-dimensional measurement device 10 at the start of measurement of the building and at the time of periodic inspection (measurement result of the three-dimensional shape acquired in advance) together with information indicating the date and time of measurement. Design information (CAD data or the like) of the three-dimensional shape of the tunnel 20 (object) can be recorded in the recording device 160. Also, the recording device 160 can record various data required for processing (selection method of data described later or the like), measurement results of each measurement point (first / second scan data or the like), data processing results (calibrated data, measurement result of the three-dimensional shape, damage candidate region, or the like), and the like.

[0113] [Processing of measurement method]

[0114] Next, a measurement method in the measurement system 1 of the above-described configuration will be described. Figure 7 、 8is a flowchart showing a process of a measurement method as one embodiment of the present application. Also, in the following, a case where the measurement device 100 is programmed as a function of the data processing device 14 and the process is mainly executed by the processor 110 (processor) will be described. Also, in a case where the measurement device 100 is a device independent of the data processing device 14, the following process can be executed by the data processing device 14 and the measurement device 100 in division.

[0115] [Setting of processing conditions]

[0116] The processor 110 sets a processing condition of measurement (step S100). The processing condition can include a scanning condition (scanning range, pitch, irradiation pattern of a laser beam, etc.) at the time of new scanning. Or, in a case where measurement is performed using data acquired in advance, the processing condition can include designation of data as a processing target. Also, the processing condition can include designation of a method (described later) of selecting points as targets of averaging process from among point groups. The processor 110 can set the processing condition according to an operation of a user via the operation section 150, or can set according to a condition determined independently of the operation of the user. Also, as for a part of the condition such as the selection method of the target points, it can be performed in the process described later (for example, in step S130).

[0117] [Acquisition of scanning data]

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

[0119] Figure 9 is a diagram showing a case where calibration is performed using measurement results in clockwise and counterclockwise directions. Figure 9 The (a) part is a diagram showing a state where scanning is performed at a certain traveling position (measurement site) of the tunnel 20, Figure 9(b) is a graph showing a state in which the clockwise (forward) direction is set as the 1st direction, and the direction opposite to the clockwise direction, that is, the counterclockwise direction is set as the 2nd direction, and the calibration result is obtained by acquiring the scan data (measurement result). Note that the scan method is not limited to this example, and it is sufficient that the 1st direction and the 2nd direction are different. Even if the 2nd direction is a direction different from the completely counterclockwise direction (the 2nd direction is not a direction completely opposite to the 1st direction), depending on the allowable calibration accuracy, it is possible to treat this 2nd direction as the "completely counterclockwise direction (a direction completely opposite to the 1st direction)".

[0120] Figure 10 is a graph showing a case where data is acquired at each measurement point by scanning. In the example shown in Figure 10 , regarding the i-th (i is an integer of 1 or more) light spot (measurement point), (distances L i , elevation angles Θ i , azimuth angles Φ i ) are associated to acquire (acquisition of the 1st scan data, the 2nd scan data). Note that the distance L i is the distance from the laser scanner 15 to the i-th light spot (measured portion on the wall surface 20A), and is the 1st distance in the case of the 1st scan, and is the 2nd distance in the case of the 2nd scan.

[0121] The processor 110 acquires such data in the 1st direction scan and the 2nd direction scan, respectively. Note that the measurement points from which data is acquired by the 1st direction scan and the 2nd direction scan are collectively referred to as the 1st measurement point group and the 2nd measurement point group, respectively.

[0122] The processor 110 can associate the rate of change (1st speed, 2nd speed) of (distance, elevation angle, azimuth angle) for each measurement point of the 1st measurement point group and the 2nd measurement point group. Note that (distance, elevation angle, azimuth angle) is equivalent to three-dimensional coordinates (x, y, z), and the rate of change of (distance, elevation angle, azimuth angle) is equivalent to three-dimensional velocity (Vx, Vy, Vz). Furthermore, the processor 110 can calculate the line-of-sight velocity V r and the tangential velocity V t of each measurement point from these data.

[0123] [Selection of pairs of measurement points]

[0124] The processor 110 selects pairs of measurement points to be calibrated (step S130). The selection can be performed, for example, by the following method. The processor 110 can determine which method to use for the selection in accordance with the user's operation via the operation section 150, or can determine without depending on the user's operation. Furthermore, the determination can be made in step S130, or can be made in the above-described step S100.

[0125] (Selection method 1)

[0126] The processor 110 performs the averaging process on all pairs of points in which the distance between a first point (a point selected from the first measurement point group) and a second point (a point selected from the second measurement point group) is equal to or less than a reference value. In the selection method 1, such pairs are selected in consideration of the fact that pairs in which the distance is equal to or less than the reference value are likely to be corresponding points (points that should have been measured as the same point). Note that the "reference value" is a reference value for pair selection, and can be a value different from the "threshold value" described below.

[0127] (Selection method 2)

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

[0129] (Selection method 3)

[0130] The processor 110 performs the averaging process on pairs of a second point and one or more first points selected from the first measurement point group in order of proximity to the second point. In the selection method 3, the first points are selected with reference to the second point, in contrast to the selection method 2.

[0131] [Calibration corresponding to distances between measurement points]

[0132] In the first embodiment, calibration (averaging process) corresponding to the distances between the selected measurement points (distances between the first measurement point and the second measurement point) is performed as described below. That is, if the distances between the measurement points are short, the averaging process is performed without using the speed data, and if the distances are long, the averaging is performed using the speed data. This is because, as long as the distances between the measurement points are short, the calibration accuracy is good even without using the speed data. Also, this is because calibration can be performed quickly by such a process. However, the averaging process in the present application is not limited to this manner, and calibration can be performed with high accuracy by performing averaging using the speed data for all pairs.

[0133] Specifically, the processor 110 determines whether the distances between the measurement points are equal to or greater than a threshold value (step S140), and if the distances are short (if less than the threshold value; "No" in step S140), the averaging process is performed without using the speed data (step S155).

[0134] [Averaging process when distances between measurement points are less than a threshold value]

[0135] The position of the 1st measurement point is set as (xl,yl,zl), and the position of the 2nd measurement point is set as (x2,y2,z2). The processor 110 can calculate these positions using the following equation (1) from the above-described (distance L i , elevation angle Θ i , azimuth angle Φ i ).

[0136] [Equation 1]

[0137] x i = L i × sin Θ i × cos Φ i

[0138] y i = L i × sin Θ i × sin Φ i

[0139] z i = L i × cos Θ i ... (1)

[0140] Then, the processor 110 can calculate the post-calibration position (x, y, z) by averaging (one way of the averaging process) the positions of the 1st and 2nd measurement points using the following equation (2) (step S155). The post-calibration position corresponds to the post-calibration data.

[0141] [Equation 2]

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

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

[0144] z = (zl+z2) / 2... (2)

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

[0146] In the case where the distance between measurement points is above a threshold value (YES in step S140), the averaging process is performed using the speed data. Figure 11 is a conceptual diagram indicating the state of the averaging process using the speed data. In Figure 11 , data is acquired by scanning in the clockwise direction (1st scan in the 1st direction) at the measurement points SP 11 - SP 17 , and data is acquired by scanning in the counterclockwise direction (2nd scan in the direction opposite to the 1st direction) at the measurement points SP 21 - SP 26The data is acquired. In the first embodiment, the position of the point at which the positions of these measurement points are divided by the ratio of the absolute values of the velocities in the respective measurement points is set as the post-calibration position (a group of points denoted by reference symbol SPt).

[0147] The following describes the averaging process using velocity data in detail. Note that the description is given in two dimensions for simplicity, but the process can be performed in the same manner in three dimensions.

[0148] Figure 12 is a graph showing the relationship between the line-of-sight velocity and the tangential velocity. In Figure 12 , subscript "1" denotes forward scanning (clockwise, first scanning), and subscript "2" denotes reverse scanning (counterclockwise, second scanning). Note that the angle θ is measured in the counterclockwise direction from the x axis toward the y axis. In this case, if the angular velocities acquired by the encoder 17 are denoted by ω1 and ω2 in the measurement points P1 and P2, the tangential velocities obtained in the forward and reverse scanning are represented by the following equation (3).

[0149] [Equation 3]

[0150] V t1 = r1 x ω1

[0151] V t2 = r2 x ω2... (3)

[0152] Here, it is assumed that the angle formed by V1 and V t1 and the angle formed by V2 and V t2 are equal under the condition that "the positions of the measurement points P1 and P2 are sufficiently close", and therefore the following equation (4) holds.

[0153] [Equation 4]

[0154] V r1 : V r2 ≈ V t1 : V t2 ... (4)

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

[0156] Figure 13 is a graph showing the state of the division of the position based on the ratio of the absolute values of the velocities. With respect to the Doppler shift, it can be represented as Δf = 2 x V r / λ, in the distance domain, 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 the measurement points P1 and P2 are r1 and r2, respectively, the measured values ​​are r1 + Δr1 and r2 + Δr2, respectively. Furthermore, according to the above-mentioned Doppler shift formula, Δr1 = V r1 ×c / (λτ), Δr2=V r2 ×c / (λτ). Δr1 and Δr2 represent the influence of Doppler shift, and “c / (λT)” is a constant determined depending on the structure of the laser scanner.

[0157] [Internal division of positions based on the ratio of absolute values ​​of velocities]

[0158] Based on the above, if the true value of the position of the measurement point expressed in orthogonal coordinates is set to (x, y) and the measured value is set to (x', y'), the relationship between the true value and the measured value at the measurement points P1 and P2 is expressed 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 influence of Doppler shift.

[0166] By combining these measured values ​​(x'1, y'1) and (x'2, y'2) with V r By dividing the absolute value ratio of θ1 and θ2, the position of the measurement point (calibrated data) without the influence of Doppler shift can be calculated as shown in the following equation (7). In equation (7), Δθ (the difference between θ1 and θ2) is sufficiently small that the first order amount 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 formula (7), the internal ratio is |V r1 |:|V r2 |, but it is also possible to divide internally at other ratios. For example, when Δθ cannot be ignored, the internal ratio with respect to x can be considered as |V r1 |cosθ1:|V r2 |cosθ2 is weighted by cosθ, and the internal ratio about y is taken as |V r1 |sinθ1:|V r2 |sinθ2 is weighted by sinθ. Furthermore, even if the polar coordinate system (r, θ) is used instead of the orthogonal coordinate system, the same formula holds true.

[0174] This process accurately calibrates the influence of Doppler shift and obtains the position of the measurement point (calibrated position of the measured portion; calibrated data). Then, by repeating the processes of steps S130 to S155 (until "Yes" is returned in step S160), position data (calibrated data) for a plurality of wall surfaces 20A (objects) can be obtained, and this data can be used to measure the three-dimensional shape of the wall surface 20A (step S170).

[0175] [Extraction of Damage Candidate Areas]

[0176] The processor 110 can calculate the design information of the three-dimensional shape of the measured three-dimensional shape of the wall surface 20A (the object) and / or the variation from the previously acquired measurement result of the three-dimensional shape, and extract a region in which the size of the variation exceeds a reference as a damage candidate region (step S180). The "design information" can be, for example, three-dimensional data generated from CAD data, and the "previously acquired measurement result" can be a past measurement result. Also, the "reference" is, for example, a threshold value of the variation, and a threshold value set by a user can also be used. Also, the processor 110 can display the extracted damage candidate region on the display device 130 (display device, output device) and / or record it in the recording device 160 (recording device, output device).

[0177] Figure 11 is a display of the display state of the damage candidate region. Specifically, it is a display example of the size of the variation of the three-dimensional shape (the above-described design information of the three-dimensional shape and / or the variation from the previously acquired measurement result of the three-dimensional shape). In the figure, the depth of the color represents the size of the variation. The deeper the color, the larger the variation, and the variation of the regions 634 and 636 is larger than that of the regions 630 and 632. In such a figure, the processor 110 can correlate (establish a correspondence) the size of the variation based on the measurement with the image or the design information of the wall surface 20A by superimposing them. In addition, the processor 110 can display the size of the variation in chroma instead of the density of the color, or can display it in combination with the density of the color and characters, numbers, graphics, symbols, charts, and the like.

[0178] In the measurement system 1, the above-described damage candidate region can be accurately measured or evaluated for damage by some measurement means (for example, a laser interferometer, non-contact acoustic vibration, image processing, and the like).

[0179] The processor 110 can display the measurement result of the three-dimensional shape and the evaluation result of the damage in time series on the display device 130 and / or record it in the recording device 160 by a chart or a graph, and also can perform prediction based on past measurement results (step S190) and output (display, record, and the like) the results. The processor 110 can extrapolate the past measurement results with a linear or nonlinear function to predict the shape change or the damage, or can use a predictor constructed by machine learning or a prediction model constructed by another method to perform the prediction. Such prediction can be reflected in the filing of the plan for evaluation, inspection, repair, and the like of the damage such as lifting.

[0180] The above describes the embodiments of the present application, but the present application is not limited to the above-described modes, and various modifications can be made.

[0181] Symbol Explanation

[0182] 1 - measurement system, 10 - three-dimensional measurement device, 11 - laser light source, 12 - tripod, 13 - control section, 14 - data processing device, 15 - laser scanner, 15A - polygon mirror, 15B - motor, 15C - half mirror, 16 - power supply device, 17 - encoder, 18 - trolley, 20 - tunnel, 20A - wall surface, 100 - measurement device, 110 - processor, 120 - memory, 130 - display device, 140 - input / output interface, 150 - operation section, 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: acquiring first scanning data, the first scanning data including information indicating a first distance, the first distance being a distance from the laser scanner to the measured portion of the object obtained by scanning the measured portion of the object along a first direction with the laser scanner; acquiring second scanning data, the second scanning data including information indicating a second distance, the second distance being a distance from the laser scanner to the measured portion, obtained by scanning the measured portion of the object with the laser scanner in a second direction different from the first direction; and By performing averaging processing on the first scan data and the second scan data, calibrated data is calculated from which the influence of Doppler shift in the first scan data and the second scan data is eliminated.

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

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

4. The measuring device according to claim 1 or 2, wherein: The processor performs the following processing: For each measurement point of the first measurement point group from which the first scanning data is obtained, a first speed as the scanning speed is included in the first scanning data for acquisition; For each measurement point of the second measurement point group from which the second scan data is obtained, a second speed as the scan speed is included in the second scan data for acquisition; The averaging process is performed on the first scanning data and the second scanning data using the first speed and the second speed.

5. The measuring device according to claim 4, wherein In the averaging process, the processor The position of the first point selected from the first measurement point group and the position of the second point selected from the second measurement point group are calculated as the calibrated data by dividing the position 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. The measuring device according to claim 5 , wherein: The processor sets the internal division ratio to 1:1 and performs the averaging process.

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

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

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

10. The measuring device according to any one of claims 1 to 3, wherein: The processor measures a three-dimensional shape of the object using the plurality of calibrated data.

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 indicating the extracted damage candidate region to an output device.

12. The measuring device according to claim 11, wherein The processor extracts, as the damage candidate region, design information of the three-dimensional shape of the object and / or a region where a variation exceeds a reference from a previously acquired measurement result of the three-dimensional shape.

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 frequency-modulated continuous-wave laser beam.

15. The measurement system according to claim 14, wherein: The laser scanner is a laser scanner using a frequency shift feedback type laser beam.

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

Images