KR20190140175A - System for measuring displacement of slope face using synthetic aperture radar (sar) sensor mounted on unmanned air vehicle, and method for the same - Google Patents

Abstract

Provided are a system and a method for measuring the displacement of a slope using a synthetic aperture radar (SAR) sensor mounted on an unmanned aerial vehicle. According to the present invention, the displacement of a slope is measured through time-series profiling of an L-band (1 to 2 GHz wavelength band) SAR image photographed by an SAR sensor mounted on an unmanned aerial vehicle (a drone). The repair and reinforcement priority of the slope can be selected by visualizing the slope with a collapse risk by analyzing measured displacement data. Therefore, the system and the method of the present invention can be used to prevent landslide for the slope of road or railroad, and steep slope around residential areas, where the frequency of occurrence is recently increased due to earthquake, severe cold, and heavy rain. In addition, a plurality of slopes in a wide area can be simultaneously managed by using a drone rather than using the conventional method of installation for each point, and the displacement of the slope can be measured at effective costs without being affected by movement of animals and plants.

Description

Slope displacement measurement system using synthetic diameter radar sensor mounted on unmanned aerial vehicle and method thereof {SYSTEM FOR MEASURING DISPLACEMENT OF SLOPE FACE USING SYNTHETIC APERTURE RADAR (SAR)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slope measurement system. More specifically, a Synthetic Aperture Radar (SAR) sensor is mounted on an unmanned drone so that multiple slopes of a large area can be simultaneously measured. A SAR sensor data analysis-based sloped displacement measurement system and method are provided.

In Korea, slopes (or slopes) collapse frequently due to mountainous topography and annual rainfall, for example 2/3 of 1300-1500 mm in summer. Not only losses, but also socio-economic damage.

Accordingly, a slope slope monitoring system or slope slope maintenance system is applied to a general national road and highway cut slope as a countermeasure for preventing slope slope in advance. The slope slope monitoring system is being developed based on the survey of the slope slope distribution, slope analysis and stability analysis, countermeasure methods, and database construction of slope slope data.

In particular, the road slope collapse monitoring system monitors whether the slope close to the road collapses due to various causes and blocks the road. For example, a system that detects the shape of the slope using a video camera or various displacement gauge sensors are used. The slope of the slope can be detected.

 However, since the slope slope monitoring system according to the prior art determines whether the slope slope collapses based on a change in the measured value generated when the slope slope collapses, the slope slope collapse cannot be known in advance. Therefore, there is a need for a method that predicts the collapse of the slope in advance, takes precautions before the collapse occurs, and detects the collapse quickly when the collapse occurs.

Moreover, in Korea, the rapid aging of the SOC, such as roads, which have been heavily invested since the 1980s, is progressing rapidly, and the cost of maintaining the SOC is increasing every year. . In particular, in the case of ground collapse accidents such as slopes, the annual occurrence amount varies depending on abnormal weather such as localized torrential rain or cold weather, but it has recently increased again.

In order to investigate the risk of slope collapse, precise displacement measurement of slope is required. For this, an expensive monitoring system is installed and operated for each slope.

On the other hand, as a prior art related to the above-described monitoring system (Monitoring System), Korean Patent Laid-Open No. 2004-3487 discloses an invention named "real time unmanned monitoring system for slope management", see FIG. Will be explained.

1 is a block diagram of a real-time unmanned surveillance system for the slope management according to the prior art.

Referring to FIG. 1, a real-time unmanned surveillance system for slope management according to the related art includes a CCD camera 11 for acquiring a surveillance image of a slope (slope) installed with a mark; A telemeter and temperature sensor 12, a rain gauge 13, and a data logger system 14 for collecting and processing measurement data such as surface displacement and rainfall on a slope; Receive and display the slope monitoring image data acquired from the CCD camera 11 through a local area network, and analyze the slope monitoring image data to determine the movement of the slope, and the telemeter, temperature sensor 12 and rain gauge ( 13) and a surveillance image and measurement data processor 16 for receiving, analyzing, and displaying slope measurement data collected by the data logger system 14 through a local area network; And a central control unit 17 for storing, managing, and analyzing the surveillance video and measurement data transmitted from the surveillance video and measurement data processing unit 16 through a long distance wired or wireless communication network to predict the collapse of the slope in advance. .

Here, the data logger system 14 includes an interface circuit 14a, a microprocessor 14b, and an RF module 14c. In addition, the real-time unmanned monitoring system for the slope management according to the prior art, further comprises a power supply unit 15 consisting of a solar cell module (15a), a battery (15b) and a regulator (15c), the data logger system It may further include an RF module 18 for performing wireless communication with the RF module 14c of (14).

According to the conventional real-time unmanned surveillance system for slope management, the slope slope by automatically measuring and monitoring the slope in real time, forecast the slope collapse in advance, and provide information on the slope through the Internet service, Minimize the loss of human and physical resources caused by the system, and use the collected measurement data to analyze the cause of the collapse and establish countermeasures.

However, the real-time unmanned monitoring system for slope management according to the prior art is an upper clock side system for slope slope measurement, and it is difficult to manage a plurality of slopes at the same time due to excessive construction cost per place, and also due to the movement of animals and plants. Frequent sensor malfunctions have limited usability. Due to these problems, for example, in Korea, only 146 of the 30,000 general slopes, which are general slopes, are installed and operated.

On the other hand, periodic safety checks on major infrastructures are being carried out, but mainly at the level of visual inspection of the points accessible by the inspector, and also the lack of manpower and resources necessary for the checks and the inaccessible facilities. In reality, the inspection cycle is limited due to the difficulty of inspection.

In order to replace these visual inspections, researches using drones and image processing techniques, which are unmanned aerial vehicles, are being actively conducted, and drones are used for inspections of facility exteriors and the like. For example, drones are used to photograph disaster areas, monitor shooting screens, and conduct rescue activities, or predict damage based on the captured images.

As a prior art related to the drone for monitoring the above-described disaster, Korean Patent No. 10-1692781 discloses an invention named "disaster management system based on drone and monitoring sensor interworking", which will be described with reference to FIG. do.

2 is a block diagram of a drone and monitoring sensor interlock-based disaster management system according to the prior art.

Referring to FIG. 2, a drone and a monitoring sensor interworking based disaster management system according to the related art includes a plurality of monitoring sensors 20, a management server 30, and a drone 50.

The plurality of monitoring sensors 20 are disposed at a predetermined interval on a natural or artificial structure, and measure at least one of satellite position information, soil water content, slope of the slope, displacement rate of the slope, temperature, and humidity, Shoot the surrounding video.

If at least one or more of the plurality of monitoring sensors 20 exceeds a management threshold, the management server 30 moves the drone 50 to a corresponding area to additionally capture a photographed image of the drone 50. In this case, the attention state is verified by collecting the photographed image of the drone 50, the photographed image of the plurality of monitoring sensors 20, and the measurement data. In addition, the management server 30 may automatically transmit the contents displayed on the web browser to the portable terminal of the manager 40.

The drone 50 3D maps the photographing area through radar photographing and provides the photographing area to the management server 30, and receives measurement data and photographed images from the plurality of monitoring sensors 20.

In addition, the management server 30 is ground fault information history of the region in which the plurality of monitoring sensors 20 is installed, photographed images of the drone 50, photographed images and measurement data of the plurality of monitoring sensors 20, satellite photographing At least one of the images and aerial photographs may be collected to produce a 3D-based ground disaster map, and early warning and warning may be issued based on the produced disaster map.

According to the conventional drone and monitoring sensor-based disaster management system, it is possible to collect the drone's image and the monitoring sensor's image and measurement data to accurately grasp the situation of the disaster area, and also to be installed at the fragile site. By linking the measurement data of the monitoring sensor with the location of the drone, it is possible to efficiently identify pre-collapse signs. In addition, spatial location information capable of acquiring a wide range of topographical displacements at a glance can be collected using a drone, and the collected information and the measurement data of the monitoring sensor can be combined to provide three-dimensional and intuitive information.

However, in the case of a drone and monitoring sensor-based disaster management system according to the prior art, the photographing of the drone and the photographing of the monitoring sensor are performed so that the measurement data of the monitoring sensor already installed at the collapse-vulnerable site and the location of the drone can be linked. Since data and data need to be collected, data processing becomes complicated. In addition, since monitoring sensors are installed at each point, multiple slopes of a wide area cannot be measured at the same time. There is a problem that you will receive.

Republic of Korea Patent No. 10-1692781 (application date: October 5, 2015), the title of the invention: "Disaster management system based on interlocking drones and monitoring sensors" Republic of Korea Patent No. 10-1457649 (application date: December 18, 2013), the title of the invention: "Slope surface collapse pre-detection system" Republic of Korea Patent No. 10-932383 (application date: May 25, 2009), the title of the invention: "Arc composite diameter radar system capable of high resolution image acquisition" Republic of Korea Patent Publication No. 2017-111921 (published: October 12, 2017), the title of the invention: "Unmanned aerial vehicle control method and system" Republic of Korea Patent Publication No. 2010-116388 (published: November 1, 2010), the title of the invention: "Vehicle-mounted slope check system" Republic of Korea Patent Publication No. 2004-3487 (published: January 13, 2004), the title of the invention: "real-time unmanned surveillance system for slope management" Republic of Korea Patent Publication No. 2012-67079 (published: June 25, 2012), the title of the invention: "Road slope collapse monitoring system and method"

The technical problem to be solved by the present invention is to measure the displacement of the slope through time series profiling of a SAR image taken with a SAR (Synthetic Aperture Radar) sensor mounted on an unmanned aerial vehicle, and measured displacement data The present invention is to provide a slope displacement measurement system and method using a SAR sensor mounted on an unmanned aerial vehicle that can determine the priority of repair and reinforcement of the slope by visualizing the slope having a collapse risk.

Another technical problem to be achieved by the present invention is unmanned, which is capable of measuring slope displacement cost-effectively without being affected by the movement of animals and plants while simultaneously managing multiple slopes of a large area using drones rather than the existing point-by-point installation. To provide a slope measurement system and method using a SAR sensor mounted on the aircraft.

As a means for achieving the above-described technical problem, the slope measurement system using the SAR sensor mounted on the unmanned aerial vehicle according to the present invention, the composite diameter radar (SAR) sensor to the slope surface along the flight trajectory so as to photograph the slope Unmanned aerial vehicles flying for access; A SAR sensor mounted on the unmanned aerial vehicle so as to acquire a SAR image of the slope, and time-lapse photographing the slope; A SAR image collecting unit for collecting SAR images of multiple periods observed in time series by the SAR sensor; A SAR image processing unit for processing the SAR image collected by the SAR image collecting unit and generating a digital map elevation model (DTM); A SAR image correction unit for generating a simulated SAR image using the flight trajectory information of the unmanned aerial vehicle and the digital map elevation model (DTM), and correcting absolute coordinates by matching the SAR image of the actual unmanned aerial vehicle; And a slope displacement analysis and visualization unit configured to analyze slope data measured through time series profiling of the SAR image to visualize slopes at risk of collapse, and to select priorities for repair and reinforcement of the slopes. do.

The slope measurement system using the SAR sensor mounted on the unmanned aerial vehicle according to the present invention further includes an unmanned aerial vehicle flight and control terminal for remotely instructing the unmanned vehicle to move and return, fly, charge, slope recognition and SAR imaging. It can be included as.

Here, the SAR sensor is preferably to take the L-band (1 ~ 21 wavelength band) SAR image.

On the other hand, as another means for achieving the above-described technical problem, the slope measurement method using the SAR sensor mounted on the unmanned aerial vehicle according to the present invention, a) to mount a compound diameter radar (SAR) sensor on the unmanned aerial vehicle step; b) photographing a SAR image for measuring time series displacement of the inclined plane by the SAR sensor along a flight trajectory of the unmanned aerial vehicle; c) collecting SAR images of multiple time periods of multiple observations of the slope; d) processing the collected SAR images and generating a digital terrain elevation model (DTM); e) generating a simulated SAR image using the flight trajectory information of the unmanned aerial vehicle and the digital terrain elevation model (DTM), and correcting absolute coordinates by matching the SAR image mounted on the actual unmanned aerial vehicle; And f) analyzing displacement of the slope and visualizing a dangerous displacement, wherein the time series profiling of the L-band (1 to 2 ㎓ wavelength) SAR image photographed using the SAR sensor mounted on the unmanned aerial vehicle is performed. Through the measurement of the displacement of the slope through the slope, and by analyzing the measured displacement data to visualize the slope of the risk of collapse, and characterized in that priorities for repair and reinforcement of the slope.

According to the present invention, by measuring the displacement of the slope through time series profiling of the SAR image taken by the SAR (Synthetic Aperture Radar) sensor mounted on the unmanned aerial vehicle, by analyzing the measured displacement data to visualize the slope of the slope It is possible to select priorities for repair and reinforcement of slopes, which can be used to prevent landslides on slopes on roads or railroads and rapidly slopes near residential areas, which are frequently increasing due to earthquakes, cold weather and heavy rains.

According to the present invention, it is possible to measure slope displacement cost-effectively without being affected by the movement of plants and animals while simultaneously managing a plurality of slopes of a large area using drones rather than the existing point-by-point installation.

1 is a block diagram of a real-time unmanned surveillance system for the slope management according to the prior art.
2 is a block diagram of a drone and monitoring sensor interlock-based disaster management system according to the prior art.
3 is a view for schematically explaining a slope measurement system using a SAR sensor mounted on an unmanned aerial vehicle according to an embodiment of the present invention.
4 is a block diagram of a slope measurement system using a SAR sensor mounted on an unmanned aerial vehicle according to an embodiment of the present invention.
5A and 5B are diagrams specifically illustrating a drone in a slope measurement system using a SAR sensor mounted on an unmanned aerial vehicle according to an exemplary embodiment of the present invention.
FIG. 6 is a block diagram illustrating a SAR image processing unit in a slope measurement system using a SAR sensor mounted on an unmanned aerial vehicle according to an exemplary embodiment of the present invention.
7 is a flowchart illustrating a method of measuring slope displacement using a SAR sensor mounted on an unmanned aerial vehicle according to an exemplary embodiment of the present invention.
8A to 8D are diagrams for describing in detail a method of measuring slope displacement using a SAR sensor mounted on the unmanned aerial vehicle illustrated in FIG. 7.
9 is a flowchart illustrating a SAR image processing process in detail in a method of measuring slope displacement using a SAR sensor mounted on an unmanned aerial vehicle according to an exemplary embodiment of the present invention.
10A to 10G are diagrams for describing in detail the SAR image processing process illustrated in FIG. 9, respectively.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, terms such as "... unit" described in the specification means a unit for processing at least one function or operation, which may be implemented in hardware or software or a combination of hardware and software.

first, 3 is a view for schematically explaining a slope measurement system using a SAR sensor mounted on an unmanned aerial vehicle according to an embodiment of the present invention.

Slope displacement measurement system using a SAR sensor mounted on the unmanned aerial vehicle according to an embodiment of the present invention, as shown in Figure 3a), the SAR (Synthetic Aperture Radar) mounted on the drone of the unmanned aerial vehicle 110 The slope of the slope is measured by time series profiling of the SAR image taken by the sensor 120, and as shown in b) of FIG. 3, the measured displacement data is interpreted to visualize the slope of the slope, thereby visualizing the slope. A repair and reinforcement priority of 200 may be selected.

A slope measurement system using a SAR sensor mounted on an unmanned aerial vehicle according to an embodiment of the present invention is implemented by using a Synthetic Aperture Radar (SAR) system mounted on the unmanned aerial vehicle 110, where the synthesis is performed. The aperture radar (SAR) system is implemented using the Doppler effect, and maintains a constant azimuth resolution regardless of the distance, and obtains images using ultra-high frequency, and thus it is possible to obtain a predetermined image without being affected by visible light, weather, and clouds. You can get information about the area. In particular, due to the Doppler effect, the system achieves much higher resolution in the azimuth direction than the existing side-looking aperture radar (SLAR).

When such a SAR system reconstructs an image from a received signal, the compression of a portion related to the distance signal processing included in the received signal and the compression of the portion related to the azimuth signal processing may be reduced. And then to correct the high frequency measurement distortion.

Slope displacement measurement system using a SAR sensor mounted on the unmanned aerial vehicle according to an embodiment of the present invention, it is possible to simultaneously manage a large number of slopes 200 of a large area using a drone, instead of the existing installation for each point, In addition, it can be used to prevent landslides on slopes of roads or railways and rapidly slopes near residential areas due to recent earthquakes, cold weather and heavy rains.

4 to 6, a slope measurement system using a SAR sensor mounted on an unmanned aerial vehicle according to an exemplary embodiment of the present invention will be described, and an exemplary embodiment of the present invention will be described with reference to FIGS. 7 to 10. A method of measuring slope displacement using SAR sensors mounted on an unmanned aerial vehicle will be described.

[Slope Slope Measurement System Using SAR Sensor on Unmanned Vehicle 100]

4 is a block diagram of a slope measurement system using a SAR sensor mounted on the unmanned aerial vehicle according to the embodiment of the present invention.

4, the slope measurement system 100 using the SAR sensor mounted on the unmanned aerial vehicle according to the embodiment of the present invention includes an unmanned aerial vehicle 110, a SAR sensor 120, and a SAR image collector 130. ), A SAR image processor 140, a SAR image corrector 150, a slope displacement analyzer 160, and an unmanned aerial vehicle flight and control terminal 170, wherein the SAR image collector 130 and SAR The image processor 140, the SAR image corrector 150, and the slope displacement analyzer 160 may be integrally implemented as one slope measurement manager terminal.

The unmanned aerial vehicle 110, for example, a drone may fly to approach the slope 200 along the flight trajectory so that the SAR sensor 120 may photograph the slope 200.

The unmanned aerial vehicle flight and control terminal 170 remotely instructs the dispatch and return of the unmanned aerial vehicle 110, flight, charging, slope recognition and SAR imaging. In this case, the unmanned aerial vehicle flight and control terminal 170 is equipped with each algorithm and processor that can remotely command the return and flight, flight, charging, slope recognition, SAR image shooting of the unmanned aerial vehicle (110). Therefore, the unmanned aerial vehicle 110 driven by the command of the unmanned aerial vehicle flight and the steering terminal 170 is flying close to the slope 200.

The SAR sensor 120 is mounted on the unmanned aerial vehicle 110 so as to acquire an L-band (1 ~ 2 ㎓ wavelength) SAR image of the slope 200 and photographs the slope 200.

In this case, the SAR sensor 120 radiates microwaves of a specific frequency from the Synthetic Aperture Radar (SAR) to the inclined plane 200 on the ground, and the same position at different times obtained from the reflected waves reflected from the inclined plane 200. Acquire a first SAR image photographed first and a second SAR image photographed subsequently from at least two SAR images photographed, and synthesize the obtained first and second SAR images in a phase of the first SAR image; Subsequently, the phase of the second SAR image photographed is subtracted, and the SAR interference degree indicating the displacement of the slope 200 is generated by the phase difference.

Specifically, SAR exploration basically radiates microwave waves in the SAR sensor 120 toward the ground, for example, the slope 200, from above. In general, the frequencies used in the SAR sensor 120 are three frequencies: an X-band (8 to 12 GHz wavelength band), a C-band (4 to 8 GHz wavelength band), and an L-band (1 to 2 GHz wavelength band). I'm using. In this case, the higher the frequency, such as the C-band (4 to 8 GHz wavelength band) and the X-band (8 to 12 GHz wavelength band), the better the resolution of the SAR image obtained. In many areas, it is difficult to obtain accurate images. Therefore, in the exemplary embodiment of the present invention, SAR images are acquired by using frequencies of L-bands (1 to 2 kHz wavelength band).

In this case, the acquired SAR image does not represent the scenery of the mountainous trees on the slope 200, and the image contains phase information about the index of the same position, and the phase is a measurement point of each slope and the SAR sensor ( 120) distance information.

In this case, the first and second SAR images include a portion of the slope 200 without the surface change and a portion where the surface change occurs, and it is difficult to identify the surface change portion only by the first and second SAR images. At this time, if there is nothing wrong with the object in the surface of the SAR image repeatedly photographed at the same position, no difference is generated, but if the movement of the object occurs, there is bound to be a difference in phase.

Therefore, a SAR interferogram that can confirm the surface displacement of the slope 200 from the first and second SAR images obtained by applying SAR interferometry (inSAR) is prepared. That is, the second and second SAR images overlapped with each other so that the same or adjacent points of the first and second SAR images coincide with each other, and are subsequently photographed in the phases of the overlapped first SAR images. Subtract the phase of.

The phase of the part with no indicator change between the phases of the two first and second SAR images shows the color of the corresponding level of the color scale with no difference, but the phase difference of the part with the indicator change is the color of the corresponding level of the color scale. Is displayed. At this time, the SAR interference degree creation process is executed by the SAR image processing unit 140 of the manager terminal implemented by a computer.

In this case, since the SAR interferogram can observe the surface displacement of the slope 200 with an accuracy of only a few centimeters to several mm in a wide region of several tens of micrometers or more, the small displacement of the slope 200 surface is accurately observed. can do.

The SAR image collection unit 130 collects SAR images taken in time series by the SAR sensor 120.

The SAR image processor 140 processes the SAR image collected by the SAR image collector 130 and generates a digital map elevation model (DTM).

The SAR image corrector 150 generates a simulated SAR image using the flight trajectory information of the unmanned aerial vehicle 110 and the DTM, and matches the absolute image by matching the SAR image of the actual unmanned aerial vehicle 110. Perform the calibration. In other words, at least one reference point or slope DTM is required for the absolute coordinate transformation of the observed displacement, where slope DTM is already required for displacement observation.

The slope displacement analysis and visualization unit 160 analyzes the displacement data of the slope 200 measured through time series profiling of the SAR image to visualize the slope 200 which is at risk of collapse, and then the surface of the slope 200 Select priorities for repair and reinforcement.

Meanwhile, FIGS. 5A and 5B are diagrams specifically illustrating a drone in a slope displacement measurement system using a SAR sensor mounted on an unmanned aerial vehicle according to an embodiment of the present invention. FIG. 5A is a configuration diagram of a drone, and FIG. 5B. Is a picture illustrating the drone.

Referring to FIG. 5A, in an inclined plane displacement measurement system using a SAR sensor mounted on an unmanned aerial vehicle, the unmanned aerial vehicle 110 includes a wireless communication module 111, a controller 112, and a memory 113. Including a flight unit 114 and a battery 115, as shown in Figure 5b, the unmanned aerial vehicle 110 includes a drone body, a propeller motor, a propeller and a landing support.

The SAR sensor 120 is rotatably mounted in the unmanned aerial vehicle 110 to photograph the slope 200.

The wireless communication module 111 receives a remote control signal from the unmanned aerial vehicle flight and control terminal 170 and transmits a SAR image photographed by the SAR sensor 120.

The controller 112 controls the flight unit 114 according to the remote control signal received through the wireless communication module 111, controls the driving of the SAR sensor 120, and photographs from the SAR sensor 120. It is implemented by the MCU to control the transmission of the data through the wireless communication module 111, the memory 113 stores the SAR image data photographed by the SAR sensor 120.

The flight unit 114 is driven under the control of the control unit 112 to fly the unmanned aerial vehicle 110 according to the remote control signal transmitted from the unmanned aerial vehicle flight and control terminal 170.

The battery 115 supplies power to the wireless communication module 111, the control unit 112, the memory 113, the flight unit 114, and the SAR sensor 120.

The unmanned aerial vehicle flight and control terminal 170 remotely directs the dispatch and return of the unmanned aerial vehicle 110, flight, charging, facility recognition and image recording. In this case, the unmanned aerial vehicle flight and control terminal 170 is equipped with an algorithm and a processor for instructing the dispatch and return of the unmanned aerial vehicle 110, flight, charging, slope recognition, SAR image shooting.

Therefore, the unmanned aerial vehicle 110 driven by the command of the unmanned aerial vehicle flight and the control terminal 170 is flying close to the slope 200 along the flight trajectory, SAR sensor 120 is abnormal of the slope 200 Take SAR images to check for presence.

On the other hand, Figure 6 is a block diagram showing the SAR image processing unit in detail in the slope measurement system using a SAR sensor mounted on the unmanned aerial vehicle according to an embodiment of the present invention.

Referring to FIG. 6, in an inclined plane displacement measuring system using a SAR sensor mounted on an unmanned aerial vehicle, the SAR image processor 140 may include a SAR image classifier 141 and a SAR image matcher 142. And a SAR interference generation unit 143, a phase alignment unit 144, and a coordinate value providing unit 145.

The SAR image classifying unit 141 utilizes an L-band (1 ~ 2 ㎓ wavelength) SAR sensor 120 mounted on the unmanned aerial vehicle 110 to display a time series (Time-) for the same slope 200 in an adjacent flight trajectory. Classify SAR image acquired in the series).

The SAR image matching unit 142 uses methods such as amplitude image correlation coefficient, interference fringe visibility, speckle tracking, and reference point matching to measure time series slope displacement. Time series SAR image co-registration is performed.

The SAR interference generating unit 143 generates a SAR interferogram that records the interference pattern of the SAR image measured in time series. Here, the interference is a pattern generated when two waves coincide (collide), for example, when two stones are thrown into water, two wave waves are generated, and waves generated when two waves collide. Means. That is, the height of the wave is doubled when two crest waves collide, and when the high and sag waves collide, it becomes flat.

The phase aligner 144 performs phase unwrapping to extract continuous physical phase values from the SAR interference degree. For example, by increasing or decreasing the multiple of 2 [pi], it is possible to eliminate the phase increase generated in the SAR interference degree, thereby restoring continuous physical phase information.

The coordinate value assigning unit 145 applies (Geo-codes) a coordinate value to the observed displacement using the SAR image. In this case, at least one ground reference point or slope surface digital terrain model (DTM) is used.

As a result, according to an embodiment of the present invention, the displacement of the slope is measured through time series profiling of an L-band (1 to 2 ㎓ wavelength) SAR image photographed with a SAR (Synthetic Aperture Radar) sensor mounted on an unmanned aerial vehicle, By analyzing the measured displacement data and visualizing the slope on which there is a risk of collapse, it is possible to select the priority for repair and reinforcement of the slope. Accordingly, roads or railways that are frequently increasing in frequency due to earthquakes, cold weather and heavy rains. Can be used to prevent landslides on steep slopes near residential areas, and also manages multiple slopes in a wide range of areas using drones rather than existing site-specific installations, while maintaining cost-effective slope displacement without affecting animals and plants. Can be measured.

[Method of Measuring Slope Displacement Using SAR Sensor on Unmanned Vehicle]

7 is a flowchart illustrating a method of measuring slope displacement using a SAR sensor mounted on an unmanned aerial vehicle according to an exemplary embodiment of the present invention, and FIGS. 8A to 8D illustrate SAR sensors mounted on an unmanned aerial vehicle illustrated in FIG. 7, respectively. Figures for explaining a slope measurement method in detail.

Referring to FIG. 7, in a method of measuring slope displacement using a SAR sensor mounted on an unmanned aerial vehicle according to an exemplary embodiment of the present invention, first, a SAR sensor 120 is mounted on an unmanned aerial vehicle 110 (S110).

Next, the SAR sensor 120 along the flight trajectory of the unmanned aerial vehicle 110 captures a SAR image for measuring the time series displacement of the slope 200 as shown in Figure 8a (S120).

Next, a multi-view SAR image is collected by multi-observing the slope 200 (S130). As shown in FIG. 8B, it is preferable to multi-view the slope 200 using a plurality of unmanned aerial vehicles 110 and SAR sensors 120.

Next, the SAR image is processed to generate a digital terrain elevation model DTM as illustrated in FIG. 8C (S140). A specific SAR image processing process will be described later with reference to FIG. 9.

Next, a simulated SAR image is generated using the flight trajectory information of the unmanned aerial vehicle 110 and the digital terrain elevation model (DTM), and matched between the SAR images mounted on the actual unmanned aerial vehicle 110. Correction of the absolute coordinate is performed (S150).

Next, the slope slope corrected by the SAR image is analyzed, and as shown in FIG. 8D, the risk displacement is visualized (S160).

According to an embodiment of the present invention, since the displacement can be measured on the plurality of slopes 200 by using the unmanned aerial vehicle 110, the slope measurement cost can be reduced as compared to the conventional clock-side system installed for each slope portion. have.

In addition, by using the SAR sensor 120 of the L-band (1 ~ 2㎓ wavelength band) it is possible to measure the displacement of the slope 120 without being affected by the vegetation. That is, the conventional image sensor, laser sensor, etc. are affected by vegetation, so it is impossible to measure displacement of the slope surface except for the growth effect of vegetation, but in the case of the SAR sensor 120 according to an embodiment of the present invention, the L-band Since the (1-2 대 wavelength band) is used, the displacement of the slope 200 can be measured without being affected by the vegetation.

Meanwhile, FIG. 9 is a flowchart illustrating a SAR image processing process in a method of measuring slope displacement using a SAR sensor mounted on an unmanned aerial vehicle according to an embodiment of the present invention, and FIGS. 10A to 10G are respectively shown in FIG. 9. FIG. 11 is a diagram for describing a SAR image processing process illustrated in detail.

Referring to FIG. 9, a SAR image processing process (S140) of a slope displacement measurement method using a SAR sensor mounted on an unmanned aerial vehicle according to an embodiment of the present invention, first, an L-band mounted on the unmanned aerial vehicle 110 is used. Using the SAR sensor 120, the SAR image 120 classifies the SAR image acquired as a time series on the same slope 200 in the adjacent flight path (S141). For example, a SAR image obtained in a time-series is classified into a master image shown in FIG. 10A and a slave image shown in FIG. 10B, where FIG. 10A represents a first SAR image, which is a master image. FIG. 10B illustrates a subsequent captured second SAR image that is a slave image.

Next, in order to measure the occurrence of time-series slopes, the first and the first and the like are measured using methods such as amplitude image correlation coefficient, interference visibility, speckle tracking, and reference point matching. Time series SAR image matching (Image co-registration) is performed on the second SAR image (S142). For example, FIG. 10C shows an unaltered first SAR image, and FIG. 10D shows a matched second SAR image.

Next, a SAR interferogram recording the interference pattern of the SAR image measured in time series is generated (S143). For example, FIG. 10E is a diagram illustrating generation of SAR interference, wherein the first and second SAR images are overlapped to coincide with the same point of the first and second SAR images, and thus overlapped. The phase of the second SAR image captured subsequently is subtracted from the phase of the first SAR image.

Next, phase unwrapping is performed to extract continuous physical phase values from the SAR interference degree (S144). For example, FIG. 10F is a diagram illustrating phase aligned.

Next, a coordinate value is assigned (Geo-coding) to the observed displacement using the SAR image (S145). In this case, at least one ground reference point or slope surface digital terrain model (DTM) is used. For example, FIG. 10G is a figure which shows that the coordinate value was provided.

Subsequently, as described above, after correcting the SAR image, the slope displacement may be analyzed to visualize the risk displacement.

As a result, according to the embodiment of the present invention, the Ministry of Land, Infrastructure and Transport to maintain the slope of 300 to 400 places by inputting a budget of 125 billion won every year, it is possible to measure the displacement of most slopes that are not currently installed slope. In addition, the damage situation such as slope collapse and rockfall tends to be increased due to sea ice or summer heavy rains, and it is possible to check on whether slope displacement occurs during sea ice and heavy rains, thereby minimizing social damage such as human damage due to slope collapse. Can be. In addition, the domestic road and railway slopes reach tens of thousands and steep slopes of 30,000, it can be used as a displacement measurement technology for the efficient management of such slopes and steep slopes. In particular, in view of the recent increase in the possibility of rapid displacement of the ground due to severe earthquakes, heavy rain, etc., the utilization thereof may be increased.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present invention is shown by the following claims rather than the above description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

100: slope displacement measurement system
110: drone 120: SAR sensor
130: SAR image collecting unit 140: SAR image processing unit
150: SAR image correction unit 160: slope displacement analysis and visualization unit
170: drone flight and control terminal
111: wireless communication module 112: control unit
113: memory 114: flight unit
115: battery
141: SAR image classification unit 142: SAR image matching unit
143: SAR interference generating unit 144: phase alignment unit
145: coordinate value provider

Claims (13)

An unmanned aerial vehicle 110 flying toward the slope 200 along the flight trajectory so that the Synthetic Aperture Radar (SAR) sensor 120 can photograph the slope 200;
A SAR sensor (120) mounted on the unmanned aerial vehicle (110) so as to obtain a SAR image of the slope (200) to photograph the slope (200) in time series;
A SAR image collection unit (130) for collecting SAR images of multiple time periods observed in time series by the SAR sensor (120);
A SAR image processing unit 140 for processing the SAR image collected by the SAR image collecting unit 130 and generating a digital map elevation model (DTM);
Simulated SAR images are generated using the flight trajectory information of the unmanned aerial vehicle 110 and the digital map elevation model (DTM), and the absolute coordinates are corrected by matching the SAR images of the actual unmanned aerial vehicle 110. A SAR image correction unit 150 to perform; And
Analyze the displacement data of the slope 200 measured through time series profiling of the SAR image to visualize the slope 200 which is at risk of collapse, and to determine the priority for repair and reinforcement of the slope 200 Displacement Analysis and Visualization (160)
Slope displacement measurement system using a SAR sensor mounted on an unmanned aerial vehicle including a. The method of claim 1,
Slope surface using the SAR sensor mounted on the unmanned vehicle further includes a drone flying and steering terminal 170 for remotely instructing the dispatch and return, flight, charging, slope recognition and SAR image shooting of the unmanned aerial vehicle (110). Displacement measuring system. The method of claim 1,
The SAR sensor 120 is a slope displacement measurement system using a SAR sensor mounted on an unmanned aerial vehicle, characterized in that to take a L-band (1 ~ 2㎓ wavelength band) SAR image. The method of claim 1, wherein the SAR image processing unit 140,
Using the L-band (1 ~ 2 ㎓ wavelength) SAR sensor 120 mounted on the unmanned aerial vehicle 110, SAR images acquired in time series on the same slope 200 on adjacent flight tracks are obtained. A SAR image classification unit 141 for classifying;
A SAR image registration unit 142 which performs time series SAR image coordination to measure whether time series slope displacement occurs;
A SAR interference generating unit 143 for generating a SAR interferogram recording an interference pattern of a SAR image measured in time series;
A phase aligner 144 for performing phase unwrapping to extract continuous physical phase values from the SAR interference degree; And
A slope measurement system using a SAR sensor mounted on an unmanned aerial vehicle comprising a coordinate value assigning unit (145) for geo-coding a displacement observed using the SAR image. The method of claim 4, wherein
The SAR image matching unit 142 performs time series SAR image matching using an amplitude image correlation coefficient, interference fringe visibility, speckle tracking, or reference point matching. A slope measurement system using a SAR sensor mounted on an unmanned aerial vehicle, characterized in that performing a). The method of claim 4, wherein
The phase aligner 144 may remove the phase increase generated from the SAR interference by increasing or decreasing the multiple of 2π, thereby restoring the SAR sensor mounted on the unmanned aerial vehicle. Slope displacement measurement system utilized. The method of claim 4, wherein
The coordinate value providing unit 145 slopes using a SAR sensor mounted on the unmanned aerial vehicle, characterized in that to assign a coordinate value using at least one ground reference point or slope digital model (Digital Terrain Model: DTM) Displacement measuring system. According to claim 1, The unmanned aerial vehicle 110,
A wireless communication module 111 for receiving a remote control signal from the unmanned aerial vehicle flight and control terminal 170 and transmitting an image signal photographed by the SAR sensor 120;
Control the flight unit 114 according to the remote control signal received through the wireless communication module 111, controls the driving of the SAR sensor 120, and the SAR image data taken from the SAR sensor 120 A control unit 112 for controlling the transmission through the wireless communication module 111;
A memory 113 for storing SAR image data photographed by the SAR sensor 120;
A flight unit (114) driven under the control of the control unit (112) to fly the unmanned aerial vehicle (110) according to the remote control signal transmitted to the unmanned aerial vehicle flight and control terminal (170); And
Utilizes a SAR sensor mounted in an unmanned aerial vehicle including a wireless communication module 111, a control unit 112, a memory 113, a flight unit 114 and a battery 145 for supplying power to the SAR sensor 120. One slope measurement system. a) mounting a Synthetic Aperture Radar (SAR) sensor 120 on the unmanned aerial vehicle 110;
b) the SAR sensor 120 photographs a SAR image for measuring a time series displacement of the slope 200 along the flight trajectory of the unmanned aerial vehicle 110;
c) collecting SAR images of multiple times obtained by multi-observing the slope 200;
d) processing the collected SAR images and generating a digital terrain elevation model (DTM);
e) Generate simulated SAR images using the flight trajectory information of the unmanned aerial vehicle 110 and the digital terrain elevation model (DTM), and absolute through the matching between the SAR images mounted on the actual unmanned aerial vehicle 110. Performing a correction of the coordinates; And
f) analyzing the displacement of the slope 200 and visualizing the risk displacement,
The displacement of the slope 200 is measured by time series profiling of the L-band (1 to 2 ~ wavelength) SAR image photographed using the SAR sensor 120 mounted on the unmanned aerial vehicle 110, and the measured displacement After analyzing the data to visualize the slope 200 which is at risk of collapse, the slope displacement measurement using the SAR sensor mounted on the unmanned aerial vehicle is characterized by selecting priorities for repair and reinforcement of the slope 200. Way. The method of claim 9, wherein the d) step,
d-1) by using the L-band (1 ~ 2 ㎓ wavelength) SAR sensor 120 mounted on the unmanned aerial vehicle 110 obtained in a time series (Time-Series) for the same slope 200 in the adjacent flight trajectory Classifying the captured SAR image;
d-2) performing time series SAR image matching to determine whether time series slope displacement occurs;
d-3) generating a SAR coherence which records the interference pattern of the SAR image measured in time series;
d-4) performing phase alignment to extract consecutive physical phase values from the SAR interference; And
d-5) A slope measurement method using a SAR sensor mounted on an unmanned aerial vehicle, the method comprising assigning a coordinate value to a displacement observed using the SAR image. The method of claim 10,
Step d-2) is a slope displacement using a SAR sensor mounted on an unmanned aerial vehicle, characterized in that time series SAR image matching is performed using an amplitude image correlation coefficient, interference fringe sharpness, speckle tracking, or reference point matching. How to measure. The method of claim 10,
In step d-4, the phase increment generated from the SAR interference can be removed by increasing or decreasing the multiple of 2π, and thus, the SAR sensor mounted on the unmanned aerial vehicle is used to restore continuous physical phase information. One slope measurement method. The method of claim 10,
Step d-5) is measured slope slope using a SAR sensor mounted on an unmanned aerial vehicle, characterized in that the coordinate value is assigned using at least one ground reference point or slope digital numerical model (DTM). Way.

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