Survey system

Abstract

To survey rivers, seas, dams, lakes, marshes, etc., more easily with higher precision by applying unmanned aerial vehicles.SOLUTION: A survey system comprises: an unmanned aerial vehicle capable of landing on a water surface; a scanner device that acquires underwater terrain data after the unmanned aerial vehicle lands on the water surface; a GNSS device that acquires an altitude of the unmanned aerial vehicle having landed on the water surface; and an RTK device that acquires correction information for correcting an altitude value output by the GNSS device. Furthermore, a river surveying method includes a process of letting the unmanned aerial vehicle flow with water streams of the river from upstream to downstream.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a surveying technique using an unmanned aerial vehicle. [Background technology]

[0002] The following Patent Document 1 discloses an unmanned aerial vehicle equipped with a float for floating the aircraft on the water surface, a screw for moving on the water surface, and a multi-beam sonar. The following Patent Document 2 discloses an unmanned aerial vehicle that uses an RTK (Real Time Kinematic) system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-041863 [Patent Document 2] International Publication No. 2018 / 168564(A1) Brochure Summary of the Invention [Problem to be solved by the invention]

[0004] With the increasing severity of flood damage due to global warming and the strengthening of disaster prevention legislation, new flood control systems and river management methods are needed to keep up. However, the rivers that are the subject of management each have their own geographical and spatial characteristics, and their conditions change constantly due to floods, making them difficult to predict. To ensure the safety of rivers into the future, it is necessary to understand the mechanisms behind river channel changes and the destruction of structures, and to quantitatively predict the hydraulic impacts of rainfall and floods. To achieve this, it is essential to be able to accurately and precisely measure the condition of rivers and their drainage basins, including their topography and geology, and to accumulate facts and knowledge. Understanding river flow, water level (elevation of the water surface), and their changes during normal and flood conditions is particularly important for river management. However, currently, there is no system that can simultaneously measure the shape of the river channel, flow velocity (speed of flow), and water level to calculate flow.

[0005] The current method uses flood discharge calculated from the water level at the reference observation station, assuming that the river channel shape will not change, but if the river channel shape changes, the river water level prediction will differ significantly, which can hinder flood control measures, flood prevention activities, and evacuation decisions.In addition, at dams, if driftwood and other objects are carried in by floods and measurements by boat are difficult, it is difficult to measure the sediment deposited on the riverbed, and it takes time to determine the effective water storage capacity.

[0006] In view of these problems, the problem that this invention aims to solve is to make it possible to survey rivers, oceans, dams, lakes, etc. more easily and with greater precision by applying unmanned aerial vehicles to such surveying. [Means for solving the problem]

[0007] In order to solve the above problem, the surveying system of the present invention comprises an unmanned aerial vehicle capable of landing on water, a scanner device that acquires underwater terrain data after the unmanned aerial vehicle lands on water, a GNSS (Global Navigation Satellite System) device that acquires the altitude of the unmanned aerial vehicle after landing on water, and an RTK device that acquires correction information for correcting the altitude value output by the GNSS device.

[0008] By floating an unmanned aerial vehicle on the water surface and using RTK correction to correct the altitude values output by its GNSS device, it is possible to obtain relatively accurate water levels. Furthermore, by floating an unmanned aerial vehicle on a river and letting it float along with the water current, it is possible to obtain the river's flow rate. Once the river channel topography data (river cross-sectional area) and flow rate are obtained, the river's flow rate can be calculated, and according to the present invention, the water level can also be obtained.

[0009] It is also preferable that the RTK device obtains the correction information via the Internet. Similarly, it is preferable that the RTK device obtains the correction information via a mobile communication network. This eliminates the need to install an RTK base station (fixed station) around the survey point each time and eliminates the constraints of distance from the RTK base station, enabling faster, easier, and more extensive surveying.

[0010] The scanner device is preferably a multi-beam echo sounder, as ultrasonic ranging is less affected by turbidity than optical cameras or green lasers, and more accurate topographical data can be obtained even under difficult conditions.

[0011] The unmanned aerial vehicle also preferably includes a control device and a rotor, which is a thrust source for moving through the air. The control device preferably acquires altitude from the GNSS device even after the rotor has stopped. In this case, the RTK device preferably acquires the correction information even after the rotor has stopped. A typical unmanned aerial vehicle uses a GNSS device solely to acquire longitude and latitude, and acquires altitude during flight using a barometric pressure sensor built into the flight controller or a downward-facing distance sensor. In other words, the altitude value output by the GNSS device is not used even during flight, especially when landing (when the rotor has stopped). In contrast, in the present invention, the GNSS device is also used to acquire water levels, so altitude must be acquired from the GNSS device even when landing on water (when the rotor has stopped). The RTK device must also be running to correct the altitude value.

[0012] The surveying system of the present invention preferably includes a data integration unit that, after the unmanned aerial vehicle lands on water, collects (1) the topographical data or its processed values acquired by the scanner device, and the longitude and latitude or time when the topographical data was acquired, and (2) the altitude value, a corrected altitude value obtained by correcting the altitude value with the correction information, or the water surface elevation obtained by subtracting the geoid height from the corrected altitude value, and the longitude and latitude or time when the altitude value was acquired. In this case, the data integration unit may calculate the river flow rate based on (1). By providing a separate component (data integration unit) specialized for collecting and integrating data acquired by the unmanned aerial vehicle and each device, the load and function of each device can be appropriately distributed throughout the entire system, and the accumulation and sharing of survey results can be more smoothly achieved.

[0013] Furthermore, it is preferable that the unmanned aerial vehicle is provided with a rotor as a thrust source for movement through the air and a water propulsion device as a thrust source for movement on the water surface. By providing a separate thrust source for moving the unmanned aerial vehicle on the water surface, the degree of freedom for surveying each water body can be increased.

[0014] In this case, it is preferable that the unmanned aerial vehicle is equipped with a control device that is capable of switching between a flight mode in which the unmanned aerial vehicle moves through the air using the rotor and a navigation mode in which the unmanned aerial vehicle moves on the water surface using the water propulsion device.

[0015] Preferably, the unmanned aerial vehicle includes a control device and a distance sensor facing the side of the aircraft, and after the unmanned aerial vehicle lands on water, the control device automatically operates the water propulsion device so that the distance between the unmanned aerial vehicle and surrounding objects does not become less than a predetermined distance. Preferably, the unmanned aerial vehicle includes a control device that automatically operates the water propulsion device so that the unmanned aerial vehicle traveling downstream on the river's water current moves along a pre-specified longitude and latitude route. Preferably, the scanner device is a multi-beam echo sounder, and the control device automatically operates the water propulsion device so that the sonar array direction of the multi-beam echo sounder is maintained in a direction intersecting the direction of travel. Preferably, the unmanned aerial vehicle includes a control device that automatically takes off and flies when the unmanned aerial vehicle traveling downstream on the river's water current reaches a predetermined position, and then lands on water at another position further downstream. These automatic piloting functions reduce the piloting skills required of the pilot and enable more accurate surveying outside visual line of sight.

[0016] Preferably, the unmanned aerial vehicle is equipped with a pair of pontoon-shaped floats, and the water propulsion device is located closer to the center of the aircraft than the pair of floats when viewed from above. Also, preferably, the unmanned aerial vehicle is equipped with a three-hull float, and the scanner device is located in a recess provided in the bottom of the central float. This protects the water propulsion device and scanner device from collisions with floating objects on the water surface or surrounding objects, allowing for safer surveying.

[0017] To solve the above problems, the river surveying method of the present invention includes a step of floating the unmanned aerial vehicle of the present invention on the water current of the river from upstream to downstream of the river. In this case, the river surveying method of the present invention may also include a step of automatically taking off and flying the unmanned aerial vehicle when it reaches a predetermined position down the river, and landing on the water at another position further downstream. The effects and principles of this method are the same as those described above, so a repeated explanation will be omitted.

[0018] The river surveying method of the present invention may also include a step of arranging a plurality of unmanned aerial vehicles of the present invention at staggered positions in the river width direction and floating them downstream along the water current of the river, thereby reducing the time required to survey a wide water area.

[0019] Furthermore, the river surveying method of the present invention may include a step of flying the unmanned aerial vehicle down the river to a predetermined position, and then returning to another position upstream from that position, and a step of flying the unmanned aerial vehicle down the river again from the other position. For example, by repeatedly observing changes in the condition of a specific part of a river during flooding or other times, it is possible to discover and understand phenomena that occur only under specific conditions. [Effects of the Invention]

[0020] As described above, according to the surveying system and river surveying method of the present invention, by applying unmanned aerial vehicles to surveying rivers, seas, dams, lakes, etc., it is possible to carry out this surveying more easily and with greater accuracy. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is a perspective view of the multicopter 12. [Figure 2] FIG. 2 is a bottom view of the multicopter 12. [Figure 3] 1 is a block diagram showing the overall configuration of a surveying system 10. FIG. [Figure 4] FIG. 2 is a block diagram showing an automatic pilot function provided in the FC / BC 20. [Figure 5] FIG. 1 is a schematic diagram showing how the multicopter 12 acquires the cross-sectional shape of a river channel. [Figure 6] FIG. 1 is a schematic diagram showing a method for calculating the flow rate of a river. [Figure 7] 1 is a schematic diagram showing a multicopter 12 riding the current of a river and descending the river. [Figure 8] This is a schematic diagram showing multiple multicopters 12 riding the current of a river and going down the river. [Figure 9] FIG. 1 is a schematic diagram showing how a multicopter 12 repeatedly surveys a specific position range of a river. [Figure 10] This is a schematic diagram showing an example in which the surveying system 10 is used not for a river but for a natural dam ND with a still water surface. [Figure 11] FIG. 10 is a bottom view showing a modified example of the multicopter 12. DETAILED DESCRIPTION OF THE INVENTION

[0022] An embodiment of the present invention will be described below with reference to the drawings. The main feature of the surveying system 10 and river surveying method described below is that a multicopter 12, which is an unmanned aerial vehicle, floats on the water surface and performs RTK correction on the altitude acquired by its GPS (Global Positioning System) 31, thereby obtaining a relatively accurate water level with little effort or constraints. This feature and other associated features will be described below through the embodiments. Note that "surveying" in the following description refers to measuring the river channel shape (topography), flow velocity, flow rate, or water level of a river, and is not limited to the meaning of "surveying" as defined in the Surveying Act. Furthermore, "water level" can also be referred to as "water surface elevation."

[0023] <Surveying system overview> Fig. 1 is a perspective view of the multicopter 12, and Fig. 2 is a bottom view of the multicopter 12. Fig. 3 is a block diagram showing the overall configuration of the surveying system 10. An overview of the surveying system 10 will be described below with reference to Figs. 1 to 3.

[0024] 1 and 2, the multicopter 12 of this embodiment is a so-called hexacopter in which rotors 12 are fixed to the tips of six arms extending radially in a plan view. The multicopter 12 is equipped with a pair of pontoon-shaped floats 50 for floating the aircraft on the water surface, and a pair of thrusters 42 is fixed to each float 50 for moving the multicopter 12 on the water surface. In addition, a sonar unit 70 is attached to the underside of the body 121 of the multicopter 12 for acquiring underwater topographical data (cross-sectional shape of the river channel) after landing on water. Two GNSS devices, GPS 31, are arranged outside the multicopter 12.

[0025] 3, the surveying system 10 of this embodiment is mainly composed of a data integrating unit 11, a multicopter 12, and a multibeam sonar 13, and the data integrating unit 11, the multicopter 12, and the multibeam sonar 13 are connected via the Internet. In this embodiment, the operation terminal of an operator 19 of the surveying system 10 is also connected to each device via the Internet.

[0026] (multicopter) The multicopter 12 of this embodiment is composed of a flight controller / boat controller 20 (hereinafter referred to as "FC / BC 20"), which is a control device, a GPS 31 connected to the FC / BC 20, an RTK receiver 32, a rotor 41, thrusters 42, a LiDAR (Light Detection And Ranging) 38, a float 50, and a camera 39. The FC / BC 20 of this embodiment includes a dedicated IMU (Inertial Measurement Unit), a barometric pressure sensor, an electronic compass, etc.

[0027] The FC / BC 20 drives the rotors 41 and thrusters 42 to fly and navigate the multicopter 12 while checking the detection values of each sensor device connected to the FC / BC 20 in response to various autopilot programs (described later) and instructions from the operator 19. In the surveying system 10 of this embodiment, the multicopter 12 is equipped with the thrusters 42, thereby increasing the freedom, flexibility, and accuracy of river surveying using the multicopter 12. Note that "navigation" here means that the multicopter 12 moves on the water surface. The multicopter 12 of this embodiment is equipped with six rotors 41 as thrust sources for movement through the air and two thrusters 42 as thrust sources for movement on the water surface. The FC / BC 20 can automatically switch between a "flight mode" in which the rotors 41 are used to move through the air and a "navigation mode" in which the thrusters 42 are used to move on the water surface, or in response to instructions from the operator 19. The operator 19 remotely controls the multicopter 12 by visual observation when the multicopter 12 is within visual range, and by relying on images transmitted from the camera 39 when it is out of visual range. In other words, if control outside visual range is left to an automatic piloting program, the camera 39 can be omitted.

[0028] The RTK receiver 32 is an RTK device that acquires correction information to correct the longitude and latitude values and altitude values acquired by the GPS 31. The RTK receiver 32 in this embodiment acquires correction information provided as an Internet service via an LTE (Long Term Evolution) line. This eliminates the need to install RTK base stations (fixed stations) around each survey point in the surveying system 10. Furthermore, the distance restrictions between the RTK receiver 32 and each RTK base station are relaxed, enabling faster, simpler, and more extensive surveying. The RTK receiver 32 may use other mobile communication networks, such as 5G, 3G, or WiMAX (Worldwide Interoperability for Microwave Access), in addition to an LTE line. While this embodiment employs GPS as the GNSS device, it may also be a receiver for other technologies, such as GLONASS, Galileo, Michibiki (Quasi-Zenith Satellite System), or COMPASS (Beidou Satellite Positioning System).

[0029] Here, the FC / BC 20 of this embodiment can continue to acquire altitude from the GPS 31 and correction information from the RTK receiver 32 even after the rotor 41 has stopped. As mentioned above, typical unmanned aerial vehicles use GPS exclusively to acquire longitude and latitude, and altitude during flight is acquired using a barometric sensor built into the flight controller or a distance sensor facing downward. In other words, the altitude output by the GPS is not generally used during flight, and even less so after landing. On the other hand, in the surveying system 10 of this embodiment, the GPS 31 and the RTK receiver 32 are also used to acquire water levels, so they must continue to operate even after landing on water (when the rotor 41 has stopped).

[0030] The LiDAR 38 is a laser scanner that is directed laterally (horizontally) from the body of the multicopter 12 and acquires point cloud data around the body. The output data of the LiDAR 38 is input to a SLAM (Simultaneous Localization and Mapping) program 231 (described later), which identifies the positional relationship between the body and its surrounding objects.

[0031] (multi-beam sonar) The multibeam sonar 13 is a multibeam echo sounding device that transmits sound beams of different frequencies in a fan-shaped pattern into the water and receives the reflected waves to acquire river topography data. The multibeam sonar 13 in this embodiment is composed of a control unit 60, a GPS 31, and a sonar unit 70.

[0032] The sonar unit 70 includes a transmitter with multiple sonar arrays, a receiver for receiving reflected waves, a dedicated IMU, and a surface sound velocity meter. The GPS 31 is the same as that used in the FC / BC 20 of the multicopter 12. The control unit 60 controls the operation and settings of the sonar unit 70, corrects the tilt of the point cloud data acquired by the sonar unit 70, and records and transmits the data acquired by the sonar unit 70. Ultrasonic measurements are less affected by turbidity than optical cameras or green lasers, enabling more accurate terrain data to be obtained even under difficult conditions. The scanner device installed on the multicopter 12 need not be a multibeam sonar 13; it is sufficient to acquire underwater terrain data after the multicopter 12 lands on the water. For example, if only highly transparent, still water areas are to be surveyed, a scanner device using an optical camera or laser could also be used to acquire terrain data. In the following description, both the multicopter 12 and the multibeam sonar 13 may be collectively referred to simply as the multicopter 12.

[0033] (Data Integration Department) The data integration unit 11 in this embodiment is a server computer, a PC, or a dedicated computer device. The data integration unit 11 may be a single device or a combination of multiple devices. Also, the function of the data integration unit 11 may be provided in the control terminal of the operator 19.

[0034] The data integrator 11 of this embodiment acquires topographical data from the multibeam sonar 13 and acquires, from the multicopter 12, the altitude value of the GPS 31, a corrected altitude value obtained by correcting this altitude value with correction information from the RTK receiver 32, or the water surface elevation (water level) obtained by subtracting the geoid height from this corrected altitude value. Note that the geoid height may be, for example, gravity geoid model data provided by the Geospatial Information Authority of Japan. The data integrator 11 also acquires the longitude and latitude and the time when the multicopter 12 and the multibeam sonar 13 acquired this data, and calculates the flow velocity of the river. Note that the flow velocity of the river may also be calculated by the multicopter 12 and transmitted to the data integrator 11.

[0035] As will be described in detail later, the data integration unit 11 calculates the river flow rate and acquires or calculates the water surface elevation of the river based on the topographical data and flow velocity. In this way, the surveying system 10 of this embodiment is equipped with a configuration (data integration unit 11) specialized for collecting and integrating data acquired by the multicopter 12 and each of its devices, thereby appropriately distributing the load and function of each device throughout the system. Furthermore, the data integration unit 11 serves as a hub for storing and sharing survey results. Note that an independent data integration unit 11 is not essential for the surveying system 10; for example, the multicopter 12 may be provided with processing functions equivalent to the data integration unit 11, and the flow rate and water surface elevation may be calculated within the multicopter 12 and transmitted to the operator 19.

[0036] In addition, in this embodiment, the multicopter 12 is equipped with an RTK receiver 32 to improve the accuracy of recognizing longitude and latitude used for automatic piloting, but if the RTK receiver 32 is used only to obtain the water surface elevation, the RTK receiver 32 may be placed in the data integration unit 11, and the altitude value obtained by the GPS 31 may be corrected by the data integration unit 11.

[0037] (Autopilot function) 4 is a block diagram showing the autopilot functions provided in the FC / BC 20. The multicopter 12 of this embodiment is provided with the following autopilot functions: an autonomous flight program 21, an autonomous navigation program 22, a collision avoidance program 23, a SLAM program 231, a heading control program 24, a flight detouring program 25, and a fixed position observation program 26. Each of the autopilot functions provided in the FC / BC 20 will be described below.

[0038] The autonomous flight program 21 is a function that automatically flies the multicopter 12 according to a flight plan prepared in advance. The flight plan is data that includes parameters such as a takeoff point (takeoff from water) and a landing point (landing on water) specified on map data, one or more waypoints that constitute the flight route, flight altitude at each waypoint, and flight speed between each waypoint.

[0039] The autonomous navigation program 22 is a function that automatically moves the multicopter 12 on the water surface according to a cruise plan (navigation plan) prepared in advance. The cruise plan is data that includes parameters of a start point, an end point, and one or more waypoints that constitute a navigation route specified on map data. The autonomous navigation program 22 automatically operates the thrusters 42 so that the multicopter 12, which rides the river current and travels downstream, moves along the navigation route.

[0040] The collision avoidance program 23 and the SLAM program 231 are functions that prevent the multicopter 12 from colliding with floating objects on the water surface or surrounding objects in the navigation mode. The SLAM program 231 determines the positional relationship between the multicopter 12 and its surrounding objects based on the output data of the LiDAR 38. The collision avoidance program 23 automatically operates the thrusters 42 based on the analysis results of the SLAM program 231 so that the distance between the multicopter 12 and its surrounding objects does not become smaller than a predetermined distance and so that the multicopter 12 does not deviate from its navigation route as much as possible. Note that the SLAM program 231 can also use a ranging sensor other than the LiDAR 38, such as one or more ultrasonic ranging sensors, laser ranging sensors, stereo cameras, depth cameras, millimeter-wave radar, etc., as long as the ranging sensor is directed to the side (horizontally) of the multicopter 12's body. Note that the collision avoidance program 23 and the SLAM program 231 can also be used in the flight mode.

[0041] The heading control program 24 is a function that controls the heading direction of the aircraft, i.e., the orientation of the multibeam sonar 13, using an electronic compass provided in the FC / BC 20. The heading control program 24 of this embodiment automatically operates the thrusters 42 to maintain the sonar array direction of the multibeam sonar 13 in an orientation that intersects (as perpendicular as possible to) the direction of travel along the navigation route of the cruise plan.

[0042] The flight detour program 25 is a function that allows the multicopter 12, which rides the river current down the river, to fly around structures that it cannot pass through, such as water intake weirs and dams. When the multicopter 12 reaches a predetermined position down the river, the flight detour program 25 automatically causes the multicopter 12 to take off and fly, and land at another position further downstream. In this embodiment, the takeoff and landing points of the flight detour program 25, as well as the flight altitude between these two points, are specified as waypoints in the cruise plan.

[0043] The fixed position observation program 26 is a function that causes the multicopter 12 to repeatedly scan the topography of a specific range of positions on the river. When the multicopter 12 reaches a predetermined position down the river, the fixed position observation program 26 automatically causes the multicopter 12 to take off and fly, land at another position upstream from that position, and then let the multicopter 12 float again in the river's water flow. In this embodiment, the takeoff and landing points of the fixed position observation program 26, the flight altitude between these two points, the number of repetitions or repetition time, etc. are specified as waypoints in the cruise plan.

[0044] As described above, the surveying system 10 of this embodiment is equipped with various automatic operation functions, and even an inexperienced operator 19 or surveying outside of visual range can perform surveying with a certain level of quality or above.

[0045] <River surveying method> Fig. 5 is a schematic diagram showing how the multicopter 12 acquires topographical data, i.e., the cross-sectional shape of a river, and Figs. 7 and 8 are schematic diagrams showing how the multicopter 12 rides the river's water current and travels down the river. Fig. 9 is a schematic diagram showing how the multicopter 12 repeatedly surveys a specific position range of the river. A river surveying method using the surveying system 10 will be described below with reference to Figs. 5 to 9.

[0046] When surveying a river using the surveying system 10, first, as shown in FIG. 5, the multicopter 12 is floated on the water surface SF of the river RV. The multicopter 12 can travel to the starting point of the cruise plan by flying or sailing. Once the multicopter 12 is floating on the water surface SF, the FC / BC 20 switches the multicopter 12 from flight mode to navigation mode. As mentioned above, the FC / BC 20 continues to operate the GPS 31 and RTK receiver 32 even after switching the multicopter 12 to navigation mode (stopping the rotor 41). Once switched to navigation mode, the multicopter 12 begins scanning the water with the multibeam sonar 13. The multibeam sonar 13 transmits a fan-shaped sound beam over a set swath width θ to acquire point cloud data representing the topography of the river channel TP. Setting the swath width θ of the multibeam sonar 13 to 180° or greater allows the current cross-sectional shape of the entire water body to be acquired.

[0047] FIG. 6 is a schematic diagram showing a method for calculating the flow rate of a river. In this embodiment, "flow rate" refers to the volume of water flowing through a cross section of a river in a predetermined unit time. For example, it is the volume of water passing through the cross section CR of the river RV shown in FIG. 6 in one second. The flow rate of the river RV is calculated by multiplying the flow velocity by the cross-sectional area of the cross section CR. The unit of measurement is cubic meters per second (m 3 / s). More specifically, the flow rate is calculated using the following formula. The flow velocity can be calculated using the longitude and latitude coordinates obtained by the GPS 31, their correction values, and the time of acquisition. Flow rate Q(m 3 / s) = flow velocity V (m / s) × cross-sectional area A (m 2 ) Generally, the flow rate of a river is calculated by converting the current water level into a flow rate based on an HQ curve (water level-flow curve) derived from multiple past flow rate measurements. However, the surveying system 10 of this embodiment can simultaneously measure the actual flow rate and obtain the water level at that time. More specifically, the HQ curve is derived by plotting the flow rate Q, calculated from the cross-sectional area A measured in advance and the flow velocity V measured using a float or other device during a flood, for each water level (H). Because the cross-sectional area A changes with the water level H, the HQ curve is an exponential curve. In river sections without water level gauging stations, the water level H is calculated by back-calculating the flow rate Q at the reference gauging station using the cross-sectional area A. However, it has been suggested that the cross-sectional shape of the river changes during a flood, and the calculated water level H may deviate from the actual water level. The surveying system 10 of this embodiment can calculate the flow rate Q based on the cross-sectional area A and flow velocity V measured during a flood and compare the result with the measured water level H.

[0048] As shown in Figure 7, the multicopter 12 floating on the river RV rides the river current and moves downstream. The autonomous navigation program 22 automatically operates the thrusters 42 so that the multicopter 12 moves downstream along the navigation route R1 of the cruise plan. If the multicopter 12 deviates from the navigation route R1, it gradually returns to the navigation route R1 while descending the river (R3). At this time, the heading control program 24 controls the heading direction so that the sonar array direction of the multibeam sonar 13 maintains a state where it intersects with the direction of travel of the navigation route R1 as much as possible. When the multicopter 12 reaches the designated position on the navigation route R1, the flight detour program 25 flies around the intake weir S1, an inaccessible structure located midway along the navigation route R1, and the multicopter 12 moves downstream to the designated position (R2). The SLAM program 231 detects a bridge pier S2 located along the navigation route R1, and the collision avoidance program 23 passes through it with the minimum necessary deviation (R4).

[0049] The flow speed of a river can vary depending on the position along the river's width. For example, even in areas where the river flows in a straight line, two spiral currents aligned along the river's width can cause the flow speed in the center of the river to be faster than that on either side of the river. Furthermore, as the river's water volume increases, the water level in the center rises, creating a flow on the surface from the center toward both banks. Conversely, as the river's water volume decreases, the water level in the center drops, creating a flow on the surface from the banks toward the center. Furthermore, in areas where the river curves, the flow speed on the outside of the curve is faster than the flow speed on the inside. Furthermore, if a floating object in deep water faces the direction of the fastest flow, it will naturally be guided toward the faster flow. Therefore, if the multicopter 12 is to be flowed along the river's fastest course, it is considered sufficient that the longitude and latitude values specified for the autopilot function are accurate enough to circumvent obstacles such as bridges.

[0050] As shown in Figure 8, in the case of a wide river, multiple multicopters 12 can be positioned at different positions in the river width direction and each can float along the river's water current. This can shorten the time required to survey a large river. Furthermore, scanning the terrain with two multibeam sonars 13 with narrow swath widths can reduce areas that are blocked by the beams, such as occlusion areas and shadow areas, rather than setting a wide swath width for one multibeam sonar 13.

[0051] Furthermore, as shown in Figure 9, when investigating changes over time in scouring and deepening near bridge pier S1 during flooding, for example, the fixed-position observation program 26 can be used to repeatedly scan the terrain within that range. Specifically, when the multicopter 12 passes by the bridge pier S1 while scanning the terrain, the multicopter 12 can be flown back to a position upstream of the pier S1 and then sent down the river while scanning again (R5). This can be repeated the number of times or for the amount of time required for the investigation. This makes it possible to discover and understand phenomena that occur only under specific conditions, such as high water levels or flooding.

[0052] FIG. 10 is a schematic diagram showing an example of using the surveying system 10 not for a river but for a still water surface natural dam (ND). The surveying system 10 can be used not only for rivers with flowing water but also for still water bodies. The multicopter 12 in FIG. 10 automatically or manually flies to the location where the natural dam (ND) has occurred and lands on the water surface of the target natural dam (ND). The thrusters 42 are then automatically or manually operated to acquire topographical data and water surface elevation of the natural dam (ND). For example, 3D topographical data can be easily acquired by stopping the multicopter 12 at a point on the water surface and rotating the aircraft in a circumferential direction while scanning the topographical data with the multibeam sonar 13.

[0053] <Modification> FIG. 11 is a bottom view showing a modified example of the multicopter 12. In the multicopter 12 of the above embodiment, when viewed from above (bottom), the thrusters 42 are disposed on the outer sides of the pair of floats 50. However, in the multicopter 12a of FIG. 11(a), the thrusters 42 are disposed closer to the center of the aircraft than the floats 50. This arrangement protects the thrusters 42 from collisions with floating objects or surrounding objects. Furthermore, in the multicopter 12 of the above embodiment, the sonar unit 70 is fixed in an exposed state to the underside of the fuselage 121 of the multicopter 12. On the other hand, the multicopter 12b of FIG. 11(b) has three-hull floats 51 and 52, and the sonar unit 70 is disposed in a recess 521 provided in the bottom of the central float 52 between the side floats 51 on both sides. This arrangement protects the sonar unit 70 from collisions with floating objects or surrounding objects.

[0054] Although the above describes an embodiment of the present invention, the scope of the present invention is not limited thereto, and various modifications can be made without departing from the spirit and scope of the invention. For example, in the above embodiment, a hexacopter is used as the unmanned aerial vehicle, but it may also be a quadcopter or octacopter with a different number of rotors, or a helicopter. In addition, in the above embodiment, two thrusters 42 are used as the water propulsion device for the multicopter 12. However, the form and number of thrusters are not particularly limited as long as they are a thrust source capable of moving the multicopter 12 on the water surface. In addition, in the above embodiment, the same GPS 31 is used for the FC / BC 20 and the multibeam sonar 13, but dedicated GNSS devices may also be provided for each. [Explanation of symbols]

[0055] 10: Surveying system, 11: Data integration unit, 12; 12a; 12b: Multicopter (unmanned aerial vehicle), 121: Fuselage, 20: Flight controller / boat controller (control device), 21: Autonomous flight program, 22: Autonomous navigation program, 23: Collision avoidance program, 231: SLAM:PG, 24: Heading control program, 25: Flight detouring program (flight detouring means), 26: Fixed position observation program, 31: GPS (GNSS device), 32: RTK receiver (RTK device), 38: LiDA R (ranging sensor), 39: camera, 41: rotor, 42: thruster (surface propulsion device), 50: float, 51: side float, 52: central float, 521: recess, 13: multi-beam sonar (scanner device, multi-beam echo sounder), 60: control unit, 70: sonar unit, RV: river, TP: river channel, SF: water surface, S1: intake weir, S2: bridge pier, ND: natural dam, CR: cross section, R1: designated route, R2: flight detour route, R3: return route, R4: collision prevention route, R5: fixed observation route

Claims

1. An unmanned aerial vehicle capable of landing on water, a scanner device for acquiring underwater topographical data after the unmanned aerial vehicle lands on water; a GNSS (Global Navigation Satellite System) device that acquires the altitude of the unmanned aerial vehicle after landing on water; and an RTK (Real Time Kinematic) device that acquires correction information for correcting the altitude value output by the GNSS device. Surveying system.

2. The RTK device acquires the correction information via the Internet. The surveying system according to claim 1 .

3. The RTK device acquires the correction information via a mobile communication network. The surveying system according to claim 1 .

4. the scanner device is a multi-beam echo sounder; The surveying system according to claim 1 .

5. The unmanned aerial vehicle comprises: a control device; a rotor that is a thrust source for moving through the air, The control device acquires altitude from the GNSS device after / after the rotor has stopped. The surveying system according to claim 1 .

6. The RTK device acquires the correction information after / also after the rotor has stopped. The surveying system according to claim 5.

7. Equipped with a data integration department, The data integration unit, after the unmanned aerial vehicle lands on water, (1) The topographical data or its processed value acquired by the scanner device, and the longitude and latitude or time when the topographical data was acquired; (2) Collect the altitude value, a corrected altitude value obtained by correcting the altitude value with the correction information, or a water surface elevation obtained by subtracting the geoid height from the corrected altitude value, and the longitude and latitude or time when the altitude value was acquired. The surveying system according to claim 1 .

8. The data integration unit Calculating the river flow rate based on (1) above; The surveying system according to claim 7.

9. The unmanned aerial vehicle comprises: A rotor is a source of thrust for moving through the air; and a water propulsion device that is a thrust source for moving on the water surface. The surveying system according to claim 1 .

10. the unmanned aerial vehicle includes a control device; The control device a flight mode in which the rotor moves through the air; a navigation mode in which the water propulsion device moves on the water surface; The surveying system according to claim 9.

11. The unmanned aerial vehicle comprises: a control device; a distance measurement sensor directed from the aircraft toward its side, After the unmanned aerial vehicle lands on water, the control device automatically operates the water propulsion device so that the distance between the unmanned aerial vehicle and a surrounding object does not become equal to or less than a predetermined distance. The surveying system according to claim 9.

12. the unmanned aerial vehicle includes a control device; The control device automatically operates the water propulsion device so that the unmanned aerial vehicle, riding on the water current of the river and traveling down the river, moves along a pre-specified route on longitude and latitude. The surveying system according to claim 9.

13. the scanner device is a multi-beam echo sounder; the control device automatically operates the surface propulsion device so as to maintain the sonar array direction of the multibeam echo sounding device in a direction intersecting with the traveling direction of the route; The surveying system according to claim 12.

14. the unmanned aerial vehicle includes a control device; the control device has a flight detouring means for automatically taking off and flying when the unmanned aerial vehicle, riding on the water current down the river, reaches a predetermined position down the river, and landing on water at another position further downstream than the predetermined position; The surveying system according to claim 9.

15. The unmanned aerial vehicle is equipped with a pair of pontoon-type floats, The water propulsion device is disposed closer to the center of the aircraft than the pair of floats when the unmanned aircraft is viewed from above. The surveying system according to claim 9.

16. The unmanned aerial vehicle is equipped with a tri-hull float, The scanner device is disposed in a recess provided in the bottom of the center float. The surveying system according to claim 1 .

17. a step of floating the unmanned aerial vehicle according to claim 1 from upstream to downstream of a river on the water current of the river, River surveying methods.

18. a step of placing a plurality of unmanned aerial vehicles according to claim 1 at staggered positions in a river width direction and floating the unmanned aerial vehicles along the water current of the river from upstream to downstream of the river, River surveying methods.

19. When the unmanned aerial vehicle has flown down the river to a predetermined position, the unmanned aerial vehicle flies back to another position upstream from the predetermined position; and again descending the river from the other position. The river surveying method according to claim 17.

20. and a step of automatically taking off and flying the unmanned aerial vehicle when the unmanned aerial vehicle reaches a predetermined position down the river, and landing on the water at another position further downstream than the predetermined position. The river surveying method according to claim 17.

Images