WO2024047798A1

WO2024047798A1 - Data analysis device, exploration system, data analysis method, and program

Info

Publication number: WO2024047798A1
Application number: PCT/JP2022/032777
Authority: WO
Inventors: 誠史吉田
Original assignee: 日本電信電話株式会社
Priority date: 2022-08-31
Filing date: 2022-08-31
Publication date: 2024-03-07
Also published as: WO2024048056A1

Abstract

The purpose of the present disclosure is to accurately identify the state of an underground object or cavity and locate the position thereof, without being restricted by the place.　Accordingly, a data analysis device 9: performs image data matching between first image data A1 of a first prescribed surface and second image data B1 of a second prescribed surface, said first image data A1 being associated with radar exploration data A2 for the first prescribed surface, said second image data B1 being associated with radar exploration data B2 for the second prescribed surface adjacent to the first prescribed surface; and combines both radar exploration data to generate composite exploration data AB2. The data analysis device 9: performs image data matching between each of third image data of a specific surface 51 and fourth image data of a specific surface 52 acquired from a ground control point measurement device 6 and specific image data that is at least one of the first and second image data and includes the specific surface 51 and the specific surface 52; and, on the basis of each absolute position associated with the third and fourth image data, performs calibration of the absolute position related to the composite exploration data AB2.

Description

Data analysis device, exploration system, data analysis method, and program

The present disclosure relates to technology for exploring buried objects or cavities in the ground of roads.

Pipelines for gas, water, sewage, electricity, or communication cables are buried underground under roadways and sidewalks. Information such as the location of these pipelines is stored in buried property registers, etc. that are individually managed by each business operator. Therefore, for example, during road excavation work, trial excavation is performed to confirm the position and depth of the buried pipe prior to construction in order to prevent damage to the pipe and cutting accidents. If the information about pipelines recorded in a buried property register or the like is inaccurate, the buried pipelines may be damaged or wasteful trial excavation may occur. Therefore, in order to efficiently maintain, manage, and update underground infrastructure facilities for new underground construction and electric wire removal projects, we have created a database of accurate location information for underground conduits. Efforts to share this information among business operators are being considered.

One method of non-destructively detecting the location of underground pipelines is to use ground penetrating radar (GPR). Ground-penetrating radar measurement equipment that implements this method emits electromagnetic waves (pulse waves) from the ground surface into the ground, and receives the electromagnetic waves reflected at interfaces with different electromagnetic properties underground. Conduct medium exploration. The characteristics of the reflected waves make it possible to non-destructively identify pipes that exist at depths of several meters from the ground surface. Furthermore, the depth of a buried pipe can be measured by measuring the travel time of the reflected wave (the time from when the electromagnetic wave is emitted to when the reflected wave is received). In this way, the position and depth of buried objects such as pipes or cavities from the ground surface can be specified without excavating the road.

Furthermore, since the attenuation and reach of electromagnetic waves vary depending on soil quality or water content, electromagnetic waves with different pulse widths or center frequencies are used depending on the target depth of exploration and resolution. Electromagnetic waves with longer wavelengths reach deeper depths, but have lower directivity and resolution. On the other hand, when the frequency of electromagnetic waves is high, although the directivity is improved, the amount of attenuation is large due to reflection near the ground surface, and the exploration depth is limited. Existing ground-penetrating radar measurement equipment uses signals with frequencies ranging from several tens of MHz to several GHz.

In the exploration of pipelines buried under roads, for example, the explorer draws measurement lines (hereinafter referred to as "measurement lines") at regular intervals in the direction across the road, and then traces the ground along these lines. Measurements will be made by scanning a cart equipped with a medium-search radar measurement device (hereinafter referred to as the "measurement cart"). In this case, since the positions of the pipelines detected in the measurement data of each survey line are connected by estimation, accurate information about the pipelines in areas other than the survey lines cannot be obtained. In addition, the position of a conduit is usually recorded as the distance on the ground from a landmark (target object) such as the edge of a sidewalk or a utility pole, but as the road environment changes over time, There are cases where it is lost.

Therefore, the location of pipelines buried underground is managed based on the absolute position (latitude, longitude, altitude) and depth from the ground surface, and the location is maintained permanently even if the surrounding environment on the ground surface changes over time. Consideration is being given to recording information that can be identified.

Furthermore, as a method for surveying pipes buried underground in the area of roads or sidewalks as three-dimensional data, the road surface is thoroughly scanned at regular intervals with a ground-penetrating radar measuring device, and multiple There is a method of pasting scan data together. This method has the advantage of being able to accurately identify the location of pipelines that cross the survey line by collecting underground exploration data in three dimensions. In actual on-site measurement work, it is not always possible to carry out measurements along the measurement line accurately, and depending on traffic conditions, the measurement cart may be temporarily stopped or the measurement cart may be stopped along the measurement line to avoid vehicles or pedestrians. There may be a temporary detour. Therefore, in order to accurately paste the measured data together, the absolute position of the underground exploration signal antenna mounted on the underground exploration radar measurement device must be accurately traced to an accuracy of approximately 10 cm or less during scanning. Location information is required.

Therefore, we are currently developing a solution that installs a GNSS (Global Navigation Satellite Systems) antenna on the measurement cart and simultaneously acquires highly accurate position information using the RTK (Real-Time Kinematic)-GNSS method while ground-penetrating radar is measuring. is used (see Non-Patent Document 1). With the RTK-GNSS method, positioning solutions with accuracy on the order of several centimeters can be obtained in a good GNSS signal reception environment. By analyzing images of reflection data obtained by slicing the three-dimensional underground exploration data synthesized using such highly accurate positioning solutions on a horizontal plane at an arbitrary depth or a vertical plane in an arbitrary direction. , explorers can learn about the three-dimensional conditions of underground pipes and cavities. Furthermore, explorers can discover pipes and waste that are not in the database (ledger) within the measurement area. Additionally, the position of the conduit can be recorded as an absolute position.

However, when using the RTK-GNSS method to perform high-precision positioning of ground-penetrating radar measurement positions, the satellite signals that can be received as direct waves are blocked by buildings etc. around the GNSS antenna. As a result, multipath signals generated by reflection or diffraction of satellite signals are received, which may degrade the accuracy of RTK-GNSS positioning solutions. In that case, it is difficult to obtain area-wide GPR measurement data (GPR reflection data images) because it is not possible to accurately paste (synthesize) the measurement data of multiple survey lines based on the positioning solution obtained by RTK-GNSS. Therefore, there was a problem in that it was not possible to accurately grasp the condition and pinpoint the location of objects such as pipes buried underground.

The present invention was made in view of the above-mentioned circumstances, and its purpose is to accurately grasp the condition and pinpoint the position of buried objects or cavities without any location restrictions.

In order to achieve the above object, the invention according to claim 1 is a data analysis device that analyzes data regarding the position of a buried object or a cavity and its depth from a predetermined surface, the data analysis device comprising: scanning a first predetermined surface; First image data obtained by photographing the first predetermined surface, which is correlated in terms of position with the obtained first radar exploration data, and a second predetermined surface adjacent to the first predetermined surface. an exploration-based image data matching unit that performs image data matching between second radar exploration data obtained by scanning and second image data obtained by photographing the second predetermined surface, which is associated with respect to position; and, based on the image data matching by the exploration system image data matching unit, the first radar exploration data and the second radar exploration data on a vertical plane of the first predetermined plane and the second predetermined plane. a data synthesis unit that generates synthetic exploration data by synthesizing the data; and association with an absolute position obtained by measuring a ground control point of a specific plane on at least one of the first predetermined plane and the second predetermined plane. third image data obtained by photographing the specific surface, and a ground control point of another specific surface different from the specific surface in at least one of the first predetermined surface and the second predetermined surface. each of the fourth image data obtained by photographing the other specific surface associated with the absolute position obtained by measuring, and at least the first image data and the second image data. On the other hand, an absolute position-based image data matching unit that performs image data matching with specific image data including the specific plane and the other specific plane, and an image data matching unit based on the image data matching by the absolute position-based image data matching unit. , and an absolute position calibration unit that performs absolute position calibration regarding the synthetic exploration data.

As explained above, according to the present invention, it is possible to accurately grasp the condition and pinpoint the position of buried objects or cavities without any restrictions on location.

1 is an overall configuration diagram of an exploration system according to an embodiment. It is a block diagram of a radar exploration device. It is a block diagram of the modification of a radar exploration device. FIG. 2 is a configuration diagram of a ground control point measuring device. FIG. 2 is an electrical hardware configuration diagram of the data analysis device. FIG. 2 is a functional configuration diagram of a data analysis device. It is a flow chart showing processing performed by a radar exploration device. It is a flow chart showing processing performed by the ground control point measuring device. It is a flow chart showing processing of a data analysis device. It is a figure showing the relationship between a measurement range and a survey line. FIG. 3 is a diagram showing the relationship between a measurement range, a measurement area, and a photographing area. FIG. 2 is a conceptual diagram showing processing for matching image data and combining radar exploration data.

Hereinafter, embodiments of the present invention will be described using the drawings.

[Summary of system configuration of embodiment]
The outline of the configuration of the exploration system according to the embodiment will be described using FIG. 1. FIG. 1 is an overall configuration diagram of an exploration system according to an embodiment.

As shown in FIG. 1, an exploration system 1 is constructed by a radar exploration device 3 installed on a measurement cart 2, a ground control point measurement device 6 installed on a tripod 4, and a data analysis device 9. . The measurement cart 2 is a cart that runs manually or automatically. For example, the measurement cart 2 may be an AGV (Automated Guided Vehicle) or the like.

The radar exploration device 3 is, for example, a GPR measurement device for measuring GPR (Ground Penetration Radar). The radar exploration device 3 transmits electromagnetic waves for exploration from the ground toward the underground, and acquires radar exploration data such as GPR reflected waves from underground. The radar exploration device 3 also photographs the ground to obtain image data of the ground. As the measurement cart 2 moves, the radar exploration device 3 scans the ground to continuously acquire radar exploration data and image data, and stores them in association with each other. The radar survey data and image data are then passed to the data analysis device 9.

The ground control point measuring device 6 measures the absolute position (latitude, longitude, altitude) of a ground control point by measuring a virtual ground control point (GCP) as an arbitrary point on the ground. GCP measurement equipment, etc. The ground control point measuring device 6 photographs a specific surface of the ground including the ground control point to obtain image data of the specific surface. The ground control point measuring device 6 stores absolute position information and image data of a specific plane in association with each other. Thereafter, the absolute position information and the image data of the specific plane are passed to the data analysis device 9.

The data analysis device 9 performs image data matching between a plurality of image data obtained from the radar exploration device 3, calculates the relative displacement amount of each radar exploration data associated with these image data, and calculates the relative displacement amount of each radar exploration data associated with these image data. Synthetic exploration data is generated by accurately combining exploration data in a planar manner. Furthermore, the data analysis device 9 performs image data matching between the image data of a specific plane obtained from the ground control point measuring device 6 and the image data obtained from the radar exploration device 3, and performs absolute position calibration regarding the synthetic exploration data. conduct. This performs data analysis regarding the absolute position of the buried object or cavity.

Note that the radar exploration device 3 may be provided in the measurement cart 2 integrally with the ground control point measurement device 6 or the data analysis device 9. When integrated, the

data storage sections

35 and 65 or the photographing

sections

36 and 66, which will be described later, may be shared.

[Each configuration in the system of the embodiment]
<Configuration of radar exploration device>
Next, the configuration of the radar exploration device 3a will be explained using FIG. 2. FIG. 2 is a configuration diagram of the radar exploration device. Note that the radar exploration device 3a is an example of the radar exploration device 3 in FIG.

As shown in FIG. 2, the radar exploration device 3a includes a GNSS antenna 30, a clock section 31, a transmitting section 33, a GPR antenna 32, a receiving section 34, a data storage section 35, and a photographing section 36. Note that although the radar exploration device 3a is a device that performs underground exploration using GPR measurement, exploration means other than GPR measurement may be used as long as buried objects, cavities, etc. can be explored.

Among these, the GNSS antenna 30 is an antenna that receives GNSS signals emitted from navigation satellites. GNSS signals include time information synchronized with UTC (Coordinated Universal Time).

The clock unit 31 has a built-in GNSS receiver, receives GNSS signals received by the GNSS antenna 30, and manages time information synchronized with UTC. In order to stamp time stamps, the clock unit 31 can synchronize the time with UTC with high precision by synchronizing with GNSS, for example, and even when the GNSS signal cannot be received temporarily under an elevated railway, etc., the clock unit 31 is built-in. The clock's holdover (self-running) operation maintains the clock's time accuracy within a certain period of time. The clock section 31 may be an atomic clock incorporating a rubidium oscillator or the like.

The GPR antenna 32 is an antenna that transmits GPR electromagnetic waves and receives GPR reflected waves therefrom. The GPR antenna 32 transmits GPR electromagnetic waves for exploration transmitted from the transmitter 33 via a coaxial cable or the like toward the ground, receives GPR reflected waves from underground, and receives data of the GPR reflected waves (hereinafter referred to as (denoted as "GPR data") is transmitted to the receiving section 34 via a coaxial cable or the like. The GPR antenna 32 may be an array type antenna in which a plurality of antenna elements are arranged and can sweep a certain width of the ground at once. Further, in order to cover a plurality of frequency regions, a plurality of transmitting sections 33 and GPR antennas 32 may be combined.

The transmitter 33 generates GPR electromagnetic waves for underground exploration and transmits them to the GPR antenna 32. The transmitter 33 may change the frequency of the signal to be transmitted stepwise on the time axis.

The receiving unit 34 receives GPR data from the GPR antenna 32 and stores it in the data storage unit 35.

The data storage unit 35 stores image data obtained by photographing by the photographing unit 36 and GPR data obtained from the receiving unit 34 in association with each other in a certain time epoch. A timestamp (an example of time information) of the data acquisition time acquired from the clock unit 31 is attached to each of these data. In addition, a survey line identifier (an example of identification information) for identifying which survey line the measurement data belongs to is recorded in each data, and the times at which measurement is started and ended for each survey line are stored. In addition,
Time information indicating a time between the start time and end time may be discarded and not stored.

The photographing unit 36 is composed of a visible light camera, and photographs the ground in the vicinity scanned by the GPR antenna 32. The number of cameras may be one, or a plurality of cameras may share the photographing range. Alternatively, it may be an omnidirectional camera equipped with a fisheye lens. Further, the camera may be a monocular camera or a stereo camera. In either case, the range of the ground photographed by the camera covers the area scanned by the GPR antenna 32, and also photographs the ground in an area of a certain width (width in the direction orthogonal to the scanning direction) on both sides of the GPR antenna 32. The scope shall be covered. This fixed width is, for example, 10 cm.

The position of the imaging unit (camera) 36 of the radar exploration device 3a and the position of the GPR antenna 32 are relatively fixed, and the relative distance (offset value) between the respective reference points is accurately measured in advance. There is. It is assumed that the photographing unit 36 photographs the ground, and that the offset between any pixel on the image data of the ground and the position of the GPR antenna 32 has been measured and calibrated in advance. At the time of measurement, the necessary illumination to photograph the photographing range of the ground is ensured by lighting, etc., as necessary. Further, the photographing unit 36 may use a far-infrared camera or the like that does not use visible light.

<Configuration of modified example of radar exploration device>
Next, the configuration of the radar exploration device 3b will be explained using FIG. 3. FIG. 3 is a configuration diagram of a modified example of the radar exploration device. Note that the radar exploration device 3b is an example of the radar exploration device 3 in FIG. Note that the same components as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 3, the radar exploration device 3b is further equipped with a gyro sensor 37, an acceleration sensor 38, and an odometry 39 compared to the radar exploration device 3a.

The gyro sensor 37 is a sensor that detects the angular velocity of the measurement cart 2 (radar exploration device 3b). The acceleration sensor 38 is a sensor that measures the acceleration of the measurement cart 2 (radar exploration device 3b). The odometry 39 is a device that measures the number of rotations of the wheels of the measurement cart 2 using a rotary encoder, for example, and calculates the moving distance, speed, and turning angle of the measurement cart 2 from the number of rotations of the wheels. The odometry 39 is a device for further increasing the accuracy of self-position estimation, and is a device that complements the gyro sensor 37 and the acceleration sensor 38, so it does not necessarily need to be provided in the radar exploration device 3b.

The data from the gyro sensor 37, the acceleration sensor 38, and the odometry 39 are transmitted to the radar exploration device 3 in between when the quality of the image data photographed by the photographing section 36 is not good or when a defect occurs in the photographing section 36. This is used to complement the position estimation of the radar exploration device 3 that has acquired the GPR data by measuring the relative displacement of the GPR data.

<Configuration of ground control point measuring device>
Next, the configuration of the ground control point measuring device 6 will be explained using FIG. 4. FIG. 4 is a configuration diagram of the ground control point measuring device.

As shown in FIG. 4, the ground control point measuring device 6 includes a GNSS antenna 60, a GNSS receiving section 61, a correction data receiving section 64, a data storage section 65, and a photographing section 66.

The GNSS antenna 60 has basically the same configuration as the GNSS antenna 30 in FIG. 2, but may have a configuration of two antennas separated by a certain distance in a horizontal plane.

The GNSS receiving unit 61 receives navigation satellite signals from a plurality of satellites from the GNSS antenna 60 and identifies the position of the GNSS antenna 60. In this case, correction data for carrier phase positioning is acquired from the correction data receiving section 64, and positioning calculations using the RTK-GNSS method are performed. Thereby, the GNSS receiving section 61 stores information on the finally specified absolute position (coordinate data) in the data storage section 65. When the GNSS antenna 60 has a two-antenna configuration, the GNSS receiving unit 61 identifies the position of each antenna, calculates absolute position (coordinate data) information and the direction of a line connecting the two antenna positions, and stores the data. 65.

The correction data receiving unit 64 receives correction data for carrier phase positioning via a communication network, etc., and transmits the correction data to the GNSS receiving unit 61. Note that the function of performing positioning calculations for the correction data receiving section 64 or the GNSS receiving section 61 may be provided on the cloud processing platform.

The data storage unit 65 stores absolute position information obtained as a result of positioning calculation by the GNSS receiving unit 61, image data obtained by the imaging unit 66, and information such as offset values in association with each other.

The configuration of the imaging unit 66 is basically the same as that of the imaging unit 36 in FIG. 2. The relative positions of the GNSS antenna 60 and the imaging unit (camera) 66 are fixed and measured. As shown in FIG. 1, the ground control point measuring device 6 is installed on the ground using the support of the tripod 4, and the photographing unit 66 photographs an image of the ground surface including a virtual GCP. The optical axis of the photographing section 66 does not necessarily have to exactly coincide with the vertical downward direction; ) is assumed to have been measured and calibrated in advance. Any pixel in the image data obtained by photography (for example, the center of the image data) becomes a virtual GCP. Alternatively, all or part of the image data may be a virtual GCP. When photographing, illuminance necessary for photographing the photographing range of the ground is ensured by lighting, etc. as necessary. The photographing unit 66 may be a far-infrared camera that uses other than visible light. In this case, the photographing unit 36 in FIG. 2 is also a far-infrared camera that uses light other than visible light.

<Configuration of data analysis device>
Since the data analysis device is configured by a computer, the electrical configuration and functional configuration will be explained separately below.

(electrical configuration)
FIG. 5 is an electrical hardware configuration diagram of the data analysis device.

As shown in FIG. 5, the data analysis device 9 includes, as a computer, a CPU 901, ROM 902, RAM 903, SSD 904, external device connection I/F (Interface) 905, network I/F 906, It includes a display 907, an input device 908, a media I/F 909, and a bus line 910.

Among these, the CPU 901 controls the operation of the data analysis device 9 as a whole. The ROM 902 stores programs used to drive the CPU 901 such as IPL. RAM903 is used as a work area for CPU901.

The SSD 904 reads or writes various data under the control of the CPU 901. Note that an HDD (Hard Disk Drive) may be used instead of the SSD 904.

The external device connection I/F 905 is an interface for connecting various external devices. External devices in this case include a display, speaker, keyboard, mouse, USB memory, printer, and the like.

The network I/F 906 is an interface for data communication via a communication network such as the Internet.

The display 907 is a type of display means such as liquid crystal or organic EL (Electro Luminescence) that displays various images.

The input device 908 is a type of input means for selecting and executing various instructions, selecting a processing target, moving a cursor, and the like. An example of the input device 908 is a pointing device.

The media I/F 909 controls reading or writing (storage) of data to a recording medium 909m such as a flash memory. The recording media 909m includes DVDs, Blu-ray Discs (registered trademark), and the like.

The bus line 910 is an address bus, a data bus, etc. for electrically connecting each component such as the CPU 901 shown in FIG. 5.

(Functional configuration)
FIG. 6 is a functional configuration diagram of the data analysis device.

As shown in FIG. 6, the data analysis device 9 includes an acquisition section 90, an exploration image data matching section 91, a data synthesis section 93, an absolute position image data matching section 95, an absolute position calibration section 97, and an output section 99. have. Each of these units is a function realized by instructions from the CPU 901 according to a program stored in the RAM 903 or the like.

Among these, the acquisition unit 90 acquires image data, radar exploration data (GPR data), identification information, time information, etc. from the radar exploration device 3 via a communication network or the like. Further, the acquisition unit 90 acquires image data, absolute position information, etc. from the ground control point measuring device 6 via a communication network or the like.

The exploration system image data matching unit 91 is configured to, for example, match images of first image data associated with the first radar exploration data in terms of position, and second image data associated with the second radar exploration data in terms of position. Perform data matching. In this case, the first predetermined surface depicted by the first image data and the second predetermined surface depicted by the second image data are adjacent to each other on the ground.

Based on the image data matching by the exploration system image data matching section 91, the data synthesis section 93 combines the first radar exploration data and the second radar exploration data on a vertical plane of the first predetermined surface and the second predetermined surface, for example. Composite exploration data is generated by calculating the relative displacement between the exploration data, correcting it, and then composing it.

The absolute position-based image data matching unit 95 uses an absolute position obtained by measuring the ground control point of a specific plane (for example, the specific plane 51 in FIG. 11) on the first predetermined plane or the second predetermined plane, for example. The third image data obtained by photographing the specific surface associated with each of the fourth image data obtained by photographing another specific surface associated with the absolute position obtained by measuring the image data, and at least one of the first image data and the second image data. , performs image data matching with specific image data including the specific plane and other specific planes.

Note that the third and fourth image data and the information on each absolute position are data acquired from the ground control point measuring device 6. Furthermore, the specific surface is not only included in the measurement range A as in the case of the specific surface 51 in FIG. It is possible that there are. In addition, in order to accurately calibrate the coordinates of the entire surface of the measurement area, it is desirable to set virtual ground control points at the four corners and five points near the center position within the measurement area. As shown in FIG. All you have to do is set the ground control point at the location. Note that when the GNSS antenna 60 of the ground control point measuring device 6 has a two-antenna configuration, it measures not only the coordinate values of the image data of a specific plane but also the direction of the image data of the specific plane. As long as the orientation and coordinate values of the image data and the second image data are determined, the ground control point may be set at one location.

Further, the specific image data may be composite image data in which first image data (measurement range A, etc.) and second image data (measurement range B, etc.) are combined. The image of the composite image data includes at least two specific surfaces (specific surfaces 51, 52, etc.). In this case, the data synthesis unit 93 synthesizes the first image data (measurement range A, etc.) and the second image data (measurement range B, etc.) to generate synthesized image data.

The absolute position calibration unit 97 performs absolute position calibration regarding the synthetic exploration data based on the image data matching performed by the absolute position system image data matching unit 95.

The output unit 99 outputs the results of the above analysis.

[Processing or operation of exploration system]
Next, the processing or operation of the exploration system will be explained using FIGS. 7 to 12.

<Radar exploration device processing>
Processing performed by the radar exploration device 3 will be explained using FIG. 7. FIG. 7 is a flowchart showing the processing performed by the radar exploration device 3.

First, the situation of the ground to be explored and the movement of the measurement cart 2 equipped with the radar exploration device 3 will be explained using FIGS. 10 and 11. FIG. 10 is a diagram showing the relationship between the measurement range and the measuring line. FIG. 11 is a diagram showing the relationship among the measurement range, the measurement area of radar exploration data, and the imaging area.

As shown in FIG. 10, a buried object 11 or a cavity 12 exists underground 10 in the ground (an example of a predetermined surface) of a region M that is a target of GPR measurement (hereinafter referred to as "measurement region"). An explorer divides the entire measurement area M into multiple areas (hereinafter referred to as "measurement Range”) Divide into A to D. Note that the ground surface in the measurement range A is an example of the first predetermined surface, and the ground surface in the measurement range B is an example of the second predetermined surface.

The explorer then moves the measurement cart 2 along each of the divided measurement ranges to draw survey lines a to d for exploration. The position of each survey line a to d may be the center line in the advancing direction of each measurement range A to D, or any position drawn parallel to the center line for scanning the measurement range with the radar exploration device 3. It may be a line. In that case, a marker is marked at the corresponding position on the radar exploration device 3, and is used as a mark for the radar exploration device 3 to correctly sweep the measurement range along the survey line.

However, in actual measurements, it is not always easy to completely scan the radar exploration device 3 along the survey line due to the unevenness of the ground, slope, road traffic conditions, etc. Therefore, in order to acquire all the data within the measurement area, as shown in FIG. 11, the measurement range ( In FIG. 11, the width of measurement range B) is set slightly smaller. That is, although there may be some overlap in the area scanned by the radar exploration device 3 to obtain radar exploration data, the area within the measurement area M is scanned without gaps.

On the other hand, the width of the ground imaging area 42 is wider than the width of the measurement area 41 for measuring radar exploration data, and is set to cover not only the measurement area 41 but also the adjacent measurement range. As an example, the relationship between the measurement range B in the measurement along the survey line b, the measurement area 41 of the radar exploration data, and the photographing area 42 of the ground is as shown in FIG. 11. That is, the width of the measurement area 41 for obtaining radar exploration data (the width in the direction orthogonal to the scanning direction) is narrower than the width of the imaging area 42 for obtaining the image data (the width in the direction orthogonal to the scanning direction). , the width of the predetermined plane such as the measurement range A is narrower than the width of the measurement area 41.

The measurement cart 2 does not necessarily need to move in the order of survey lines a, b, c, . . . The radar exploration device 3 repeatedly performs exploration while moving the measurement cart 2 along each survey line. The exploration of each survey line does not need to be carried out consecutively in time, and can be carried out at any arbitrary time.

Under the above circumstances, the processing of the radar exploration device 3 will be explained with reference to FIG.

S11: As shown in FIG. 10, by moving the measurement cart 2, the GPR antenna 32 and the imaging unit 36 simultaneously acquire ground radar exploration data and ground image data.

S12: The data storage unit 35 stores radar exploration data and image data, as well as survey line identification information and acquisition time information in association with each other.

S13: If the imaging and exploration scans have not been completed (NO), return to process S11. On the other hand, if the imaging and exploration scans are completed (YES), the process in FIG. 7 is completed.

When measuring with the radar exploration device 3, a measurement area (measurement area M in Fig. 10) is selected on a map displayed on the screen of an operating terminal of the explorer, etc., and the measurement range and survey line are automatically set. may be done. Furthermore, positioning results obtained by composite positioning using GNSS/INS (Inertial Navigation System) may be used to perform machine guidance for manual movement operation of the measurement cart 2 along the survey line or for automatic travel of the measurement cart 2.

<Processing of ground control point measuring device>
Next, the processing performed by the ground control point measuring device 6 will be described using FIG. 8. FIG. 8 is a flowchart showing the processing performed by the ground control point measuring device 6.

First, the situation of the ground to be measured (explored) and the installation position of the tripod 4 on which the ground control point measuring device 6 is installed will be explained using FIGS. 10 and 11.

The position of the GCP measurement point within the measurement area M may be determined in advance, such as the specific surface 51 in FIG. Any position within M may be selected as a GCP measurement point. Furthermore, RTK-GNSS positioning may be repeatedly performed at different time zones until a valid GNSS positioning solution is obtained at the same location. The timing of GNSS positioning in the GNSS receiving section 61 of the ground control point measuring device 6 and the timing of photographing in the photographing section 66 do not necessarily have to coincide unless the installation position of the tripod 4 on which the ground control point measuring device 6 is installed is moved. For example, RTK-GNSS positioning may be started after photographing the ground near a virtual GCP using the ground control point measuring device 6, and positioning may be continued until an effective convergence (FIX) solution is obtained.

Under the above circumstances, the processing of the ground control point measuring device 6 will be explained with reference to FIG. Note that although the specific surface 51 of the measurement range A shown in FIG. 11 will be described here, the specific surface is not limited to this specific surface 51.

S21: The GNSS receiving unit 61 measures the absolute position of the specific surface 51 of the ground based on the GNSS signal and correction data on the specific surface 51.

S22: The photographing unit 66 acquires image data of the specific surface 51.

S23: The data storage unit 65 stores the control point data including the absolute position of the specific surface 51 and the image data of the specific surface in association with each other.

Since the ground control point (GCP) of this embodiment is a virtual one based on image data of the road surface, there is no need to install physical signs or markers on the ground, and any point within the measurement area M can be used as a GCP. Can be set. Therefore, a point with as good a GNSS signal reception environment as possible can be selected as a GCP without being restricted by the position of a sign or marker. Furthermore, since the position of the GNSS satellite in the sky changes over time, it is also possible to perform GCP measurements by selecting a time period when a good positioning solution is likely to be obtained based on the positional relationship with surrounding structures. be.

As a method of predicting GNSS reception characteristics (possibility of positioning), for example, 3D map data including building height information is used, and the DOP (Dilution Of Precision) value of the GNSS visible satellite signal is reduced (better). There is a way to select the time zone. If RTK-GNSS positioning at the GCP measurement point is still difficult, the ground control point measurement device 6 shown in Figure 1 can be mounted on a flying vehicle such as a drone, and the RTK-GNSS positioning at the GCP measurement point can be carried out in the sky where the area around the GNSS antenna 60 is not obstructed by structures. -It is possible to perform GNSS positioning and photograph the ground near GCP measurement points using a telephoto lens. In this case, signs or markers may be installed on the ground to make it easier to identify the location of the GCP from the sky. If positioning at the GCP measurement point is still difficult, optical ranging means such as a total station may be used in combination.

<Processing of data analysis device>
Next, the processing performed by the data analysis device 9 will be explained using FIG. 9. FIG. 9 is a flowchart showing the processing performed by the data analysis device. Note that the analysis processing by the data analysis device 9 may be performed in real time while the radar exploration device 3 is exploring, or may be performed (offline) after the radar exploration device 3 is exploring.

S31: The acquisition unit 90 acquires each data from the radar exploration device 3 and the ground reference point measurement device 6.

S32: The exploration system image data matching unit 91 performs image data matching of the data (first and second image data, etc.) acquired from the radar exploration device 3. For example, as shown in FIG. 12, the exploration system image data matching unit 91 receives image data A1 including the first predetermined surface, which is the ground of the measurement range A, from the radar exploration device 3, and the measurement data adjacent to the measurement range A. Image data matching is performed with image data B1 including a second predetermined surface that is the ground in range B. As shown in FIG. 12, the ground area indicated by the radar exploration data A2 is wider than the measurement range A, and the range of the image data A1 is wider than the ground area indicated by the radar exploration data A2. Similarly, the ground area indicated by the radar exploration data B2 is wider than the measurement range B, and the range of the image data B1 is wider than the ground area indicated by the radar exploration data B2. Therefore, the imaging areas of image data A1 and image data B1 partially overlap. The image data A1 and B1 are two-dimensional planar images, but the radar exploration data A2 and B2 are three-dimensional rectangular parallelepiped data as shown in FIG. Note that the image data A1 is an example of first image data, and the image data B1 is an example of second image data. Further, the radar exploration data A2 is an example of first radar exploration data, and the radar exploration data B2 is an example of second radar exploration data.

Since the relative offset between the reference point of the image data (any pixel in the image data) and the position of the GPR antenna 32 is measured in advance, the exploration system image data matching unit 91 performs matching of the adjacent image data when matching the image data. It is possible to calculate the relative displacement amount between the radar exploration data A2 and the radar exploration data B2 of the survey line.

Specifically, the exploration-based image data matching unit 91 matches image data obtained by measurements of adjacent survey lines photographing the same ground area. The exploration image data matching unit 91 extracts from the image data the texture information of the road surface obtained from the road surface properties such as unevenness and cracks on the surface layer of the pavement surface of the road, or the painted condition of the lines. Perform matching. For example, the exploration system image data matching unit 91 generates an image within a measurement range B on the left side when facing the traveling direction (x direction) of the measurement cart 2 (radar exploration device 3), which was photographed while scanning the survey line a in FIG. 10. The data (image data A1 in FIG. 12) is matched with the image data (image data B1 in FIG. 12) within the measurement range B photographed in the measurement of the survey line b.

In addition, the exploration system image data matching unit 91 uses image data (image data B1 in FIG. 12) within the measurement range A on the left side of the traveling direction (-x direction) of the radar exploration device 3, which was photographed during the measurement of the survey line b. , is matched with the image data (image data A1 in FIG. 12) within the measurement range A that was photographed during the measurement of the measuring line a. At this time, the exploration image data matching unit 91 may narrow down the range of image data to be matched by referring to time stamp data in addition to the survey line identifier of the measurement data of each survey line.

In the case of the modified radar exploration device 3b, the exploration system image data matching unit 91 further refers to data from the gyro sensor 37, acceleration sensor 38, or odometry 39 to determine the range of image data to be matched. You can also narrow down the results. Once the image data has been matched, the exploration image data matching unit 91 may narrow down the matching target to corresponding image data at times before and after the matching.

S33: The data synthesis unit 93 synthesizes the data acquired from the radar exploration device 3 (first and second radar exploration data, etc.) based on image data matching to generate composite exploration data. For example, as shown in FIG. 12, the data synthesizing unit 93 synthesizes the radar exploration data A2 and the radar exploration data B2 on a plane perpendicular to the first predetermined plane and the second predetermined plane, thereby generating the synthesized exploration data. Generate AB2.

Specifically, the data synthesis unit 93 calculates the amount of displacement in the traveling direction of the measurement cart 2 (radar exploration device 3) from image data and time stamps (obtained time information) within the same survey line, and also From the relative displacement of the radar exploration data of adjacent survey lines obtained by the image data matching unit 91, the amount of displacement in the direction orthogonal to this is calculated, and based on this, the radar exploration data is pasted and synthesized. When combining radar survey data at overlapping positions, one of them is deleted as appropriate and combined.

By repeating the above processing, it is possible to obtain a planar ground surface image of the entire measurement area M and three-dimensional radar exploration data (synthetic exploration data). The method of this embodiment is characterized in that, based on each image data of the ground surface, the relative positional relationship of radar exploration data linked to image data is specified. Since the reference points of the imaging unit 36 of the radar exploration device 3 and the GPR antenna 32 have a physically fixed relative positional relationship, radar exploration data measured on different survey lines can be synthesized with high accuracy.

S34: The absolute position system image data matching unit 95 matches the data acquired from the ground reference point measurement device 6 (for example, each of the third and fourth image data) and the data acquired from the radar exploration device 3 (the third image data). image data (specific image data related to the first and second image data) is performed. Note that the specific image data related to the first and/or second image data is at least one of the first image data and the second image data, and includes a specific surface (such as the specific surface 51) and another specific surface (such as the specific surface 51). This is image data including a specific surface 52, etc.).

The composite exploration data generated by combining multiple pieces of radar exploration data based on the relative displacement amount in the steps up to S33 has its relative position determined based on the unique coordinate system of the measurement area M. However, absolute coordinates are further linked to this coordinate system using information on the absolute positions of image data of a plurality of GCP measurement points measured by the ground control point measurement device 6.

The matching process between the image data of the GCP measurement point taken during ground control point measurement and the image data taken during GPR measurement is based on the approximate position of the GCP measurement point, and the line identifier (identification information) and time stamp (time information) of the GPR measurement data. The range of image data to be matched may be narrowed down by referring to the data in .

S35: The absolute position calibration unit 97 performs absolute position calibration regarding the synthetic exploration data based on image data matching.

Once the image data matching process is completed in step S34, the coordinates of the entire radar exploration data are calibrated to absolute coordinates using the coordinate values of a plurality of virtual GCPs. This is basically the same procedure as calibrating the coordinate data of the entire orthogonal image of an aerial photograph using the absolute coordinate position information of multiple GCPs reflected in the aerial photograph. When performing GCP measurement and GPR measurement at the same time, calibrate the absolute position by selecting and using appropriate GCP position data from the data for which a valid positioning solution was obtained by GCP measurement.

S36: The output unit 99 outputs the analysis result.

[Application example of this embodiment]
This embodiment can be applied not only to exploring the buried object 11 or cavity 12 in the underground 10 from the ground as shown in FIG. 10, but also to exploring the inside of a concrete wall or the like.

Furthermore, this embodiment can be used for data collection purposes other than underground exploration data, such as collecting 3D point cloud data on the ground using stereo cameras, LiDAR (Light Detection And Ranging), and imaging RADAR (Radio Detection And Ranging). method may be applied.

[Effects of embodiment]
As explained above, according to the present embodiment, there is no restriction on location, and there is an effect that the state and position of a buried object or cavity can be accurately determined.

Furthermore, according to this embodiment, it is possible to calibrate the absolute position of radar exploration data with high precision even in an environment where it is difficult to receive GNSS satellite signals, and to obtain highly accurate three-dimensional data of underground pipes. In addition, measurement of each survey line can be carried out in any order and at any time, making it possible to flexibly formulate work plans.

Since the manhole shaft position can be identified on the radar exploration data image, it is possible to consider the manhole position (center) on the ground as the GCP, but the manholes are not installed in the measurement area M at a sufficient density as the GCP. There is a high possibility that the GCP cannot be taken at the ideal position such as the four corners or the center of the measurement area M. Furthermore, it is not always possible to obtain a good reception environment for GNSS signals at the location of a manhole.
Another possible method is to collect data on the surrounding environment using the imaging unit (camera) 36, LiDAR, RADAR, etc. mounted on the radar exploration device 3, and to identify the position of the radar exploration device 3 by performing scan matching on an environmental map. However, in order to achieve the required position estimation accuracy (approximately 10 cm or less), there are formal issues such as the need to prepare extremely high-precision environmental maps.

In the method of using an IMU (Inertial Measurement Unit) to measure the displacement associated with the scanning of the radar exploration device 3, in order to measure the displacement of the radar exploration device 3 between multiple survey lines, data from adjacent survey lines are used. Continuous measurements are required, and there is also the problem of cumulative errors in the IMU.

Furthermore, it is possible to increase the overlapping area in the measurement areas of radar survey data of adjacent survey lines, use the image of the radar survey data itself for matching processing, and paste the radar survey data together, but it is possible to combine the radar survey data. Images have inferior spatial resolution compared to road surface image data and have fewer feature points, so there are issues with the feasibility and accuracy of matching processing. Furthermore, as the overlapping area of the measurement area is increased, the interval between the survey lines becomes narrower, resulting in a disadvantage that the overall amount of work increases.

Additionally, methods that automatically combine radar exploration data using machine learning, etc. have problems with processing load and are not practical.

On the other hand, in this embodiment, the above-mentioned problem is solved because the measurement data is synthesized in a plane using the ground texture characteristics of a predetermined surface and the absolute position is specified by virtual GCP. can do.

〔supplement〕
As described above, the present invention is not limited to the above-described embodiments, and various modifications and applications can be made, for example, as shown below.

(1) The data analysis device 9 can be realized by a computer and a program, but this program can also be recorded on a (non-temporary) recording medium or provided via a communication network such as the Internet.

(2) The CPU 901 (microprocessor) may not only be a single CPU but may also be a plurality of CPUs.

1 Exploration system 2 Measurement cart (an example of a moving object)
3 Radar exploration device 4 Tripod 6 Ground control point measurement device 9 Data analysis device 90 Acquisition section 91 Exploration system image data matching section 93 Data synthesis section 95 Absolute position system image data matching section 97 Absolute position calibration section 99 Output section A1 Image data (Example of first image data)
B1 Image data (an example of second image data)
A2 Radar exploration data (first radar exploration data)
B2 Radar exploration data (second radar exploration data)
AB2 Synthetic exploration data

Claims

A data analysis device that analyzes data regarding the position and depth of a buried object or cavity from a predetermined surface,
first image data obtained by photographing the first predetermined surface, which is correlated in terms of position with first radar exploration data obtained by scanning the first predetermined surface; an image of second radar exploration data obtained by scanning a second predetermined surface adjacent to the surface and second image data associated with position and obtained by photographing the second predetermined surface; An exploration image data matching unit that performs data matching;
The first radar exploration data and the second radar exploration data are combined on a vertical plane of the first predetermined plane and the second predetermined plane based on image data matching by the exploration system image data matching unit. a data synthesis unit that generates synthetic exploration data by
A third predetermined surface obtained by photographing the specific surface is associated with an absolute position obtained by measuring the ground control point of the specific surface on at least one of the first predetermined surface and the second predetermined surface. The image data is associated with an absolute position obtained by measuring a ground control point of another specific surface different from the specific surface on at least one of the first predetermined surface and the second predetermined surface. and at least one of the first image data and the second image data, and includes the specific surface and the other specific surface. an absolute position image data matching unit that performs image data matching with specific image data;
an absolute position calibration unit that calibrates the absolute position regarding the synthetic exploration data based on image data matching by the absolute position system image data matching unit;
A data analysis device with
The first image data is associated with first identification information for identifying the first predetermined surface, and the second image data is associated with first identification information for identifying the second predetermined surface. 2 identification information is associated,
The exploration image data matching unit performs image data matching with the first image data and the second image data based on the first identification information and the second identification information.
The data analysis device according to claim 1.
The first image data is associated with first time information when the first predetermined surface is scanned, and the second image data is associated with second time information when the second predetermined surface is scanned. Time information is associated,
The exploration image data matching unit narrows down a range to be matched between the first image data and the second image data based on the first time information and the second time information.
The data analysis device according to claim 1.
A data analysis device that analyzes data regarding the position and depth of a buried object or cavity from a predetermined surface,
first image data obtained by photographing the first predetermined surface, which is correlated in terms of position with first radar exploration data obtained by scanning the first predetermined surface; an image of second radar exploration data obtained by scanning a second predetermined surface adjacent to the surface and second image data associated with position and obtained by photographing the second predetermined surface; An exploration image data matching unit that performs data matching;
The first radar exploration data and the second radar exploration data are combined on a vertical plane of the first predetermined plane and the second predetermined plane based on image data matching by the exploration system image data matching unit. a data synthesis unit that generates synthetic exploration data by
The first predetermined surface obtained by photographing the specific surface is associated with the absolute position and orientation obtained by measuring the ground control point of the specific surface on at least one of the first predetermined surface and the second predetermined surface. an absolute position system image data matching unit that performs image data matching between the image data of No. 3 and specific image data that is at least one of the first image data and the second image data and includes the specific surface;
an absolute position calibration unit that calibrates the absolute position regarding the synthetic exploration data based on image data matching by the absolute position system image data matching unit;
A data analysis device with
A data analysis device according to any one of claims 1 to 3,
The first radar exploration data and the first image data are obtained by scanning the first predetermined surface, and the second radar exploration data and the first image data are obtained by scanning the second predetermined surface. a radar exploration device that obtains image data of 2;
Obtaining the absolute position of the specific surface by measuring the ground control point of the specific surface, obtaining the third image data by photographing the specific surface, and measuring the ground control point of the other specific surface. a ground control point measuring device that obtains the absolute position of the other specific surface by doing so and obtains the fourth image data by photographing the other specific surface;
An exploration system with
The width of the measurement area for obtaining the first and second radar exploration data is narrower than the width of the imaging area for obtaining the first and second image data, and the first and second predetermined surfaces The exploration system according to claim 5, wherein the width of the measurement area is narrower than the width of the measurement area.
A data analysis method executed by a data analysis device that analyzes data regarding the position and depth of a buried object or cavity from a predetermined surface,
The data analysis device includes:
first image data obtained by photographing the first predetermined surface, which is correlated in terms of position with first radar exploration data obtained by scanning the first predetermined surface; an image of second radar exploration data obtained by scanning a second predetermined surface adjacent to the surface and second image data associated with position and obtained by photographing the second predetermined surface; Exploration-based image data matching processing that performs data matching,
The first radar exploration data and the second radar exploration data are combined on a vertical plane of the first predetermined plane and the second predetermined plane based on image data matching by the exploration system image data matching process. A data synthesis process that generates synthetic exploration data by
A third predetermined surface obtained by photographing the specific surface is associated with an absolute position obtained by measuring the ground control point of the specific surface on at least one of the first predetermined surface and the second predetermined surface. The image data is associated with an absolute position obtained by measuring a ground control point of another specific surface different from the specific surface on at least one of the first predetermined surface and the second predetermined surface. and at least one of the first image data and the second image data, and includes the specific surface and the other specific surface. Absolute position image data matching processing that performs image data matching with specific image data;
Absolute position calibration processing that calibrates the absolute position regarding the synthetic exploration data based on image data matching by the absolute position system image data matching processing;
Data analysis method to perform.
A program that causes a computer to execute the method according to claim 7.