Surveying System

Abstract

By using unmanned aerial vehicles to survey rivers, seas, dams, lakes, etc., this can be done more easily and with greater precision. [Solution] This problem is solved by a surveying system comprising an unmanned aerial vehicle capable of landing on the water surface, a scanner device that acquires underwater topography data after the unmanned aerial vehicle lands on water, a GNSS 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, and a river surveying method that includes a step of floating the unmanned aerial vehicle of the present invention on the water current of the river from upstream to downstream.

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 worsening of flood damages due to global warming and the strengthening of legal systems for disaster prevention, new flood control systems and river management methods that are comparable to these are required. On the other hand, the rivers that are the subject of management each have their own geographical and spatial characteristics, and are difficult to predict because their state changes from moment to moment due to floods. In order to maintain the safety of rivers into the future, it is necessary to clarify the mechanisms of river channel changes and the destruction of structures, etc., and to quantitatively predict the hydraulic effects of rainfall and floods. To achieve this, it is essential to be able to accurately and in detail measure the state of rivers and their drainage basins, including topography and geology, and to accumulate facts and knowledge. In particular, it is important to understand the flow rate, water level (elevation of the water surface), and changes of rivers during normal and flood times in order to manage rivers, but 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 the flow rate.

[0005] In the current method, flood discharge is calculated from the water level at the standard observation station on the assumption that the river channel shape will not change, but if the river channel shape changes, the river water level prediction may differ significantly, which may hinder flood control, flood prevention activities, and evacuation decisions.In addition, in dams, if driftwood and other objects flow in due to flooding 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 storage volume.

[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 accuracy by using unmanned aerial vehicles. [Means for solving the problem]

[0007] In order to solve the above problems, the surveying system of the present invention comprises an unmanned aerial vehicle capable of landing on the surface of water, a scanner device that acquires underwater topography 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 performing RTK correction on the altitude value output by the GNSS device, it is possible to obtain a relatively accurate water level. Also, by floating an unmanned aerial vehicle on a river and letting it float with the water flow, it is possible to obtain the flow rate of the river. If the topographical data of the river channel (river cross-sectional area) and the flow rate are obtained, the flow rate of the river 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 is free from the constraints of the distance from the RTK base station, making it possible to conduct surveys more quickly, easily, and widely.

[0010] Moreover, the scanner device is preferably a multi-beam echo sounder, since 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] Moreover, the unmanned aerial vehicle includes a control device and a rotor, which is a thrust source for moving through the air, and the control device preferably acquires the altitude from the GNSS device after / after the rotor stops. In this case, the RTK device preferably acquires the correction information after / after the rotor stops. A typical unmanned aerial vehicle uses the GNSS device solely to acquire longitude and latitude, and acquires altitude during flight using an air pressure sensor built into the flight controller or a distance sensor facing downward. In other words, the altitude value output by the GNSS device is not used even during flight. This is even more so when landing (when the rotor stops). On the other hand, in the present invention, the GNSS device is also used to acquire water levels, so it is necessary to acquire altitude from the GNSS device even when landing on water (when the rotor stops). In addition, it is necessary to operate the RTK device to correct the altitude value.

[0012] The surveying system of the present invention preferably includes a data integration unit, which, after the unmanned aerial vehicle lands on water, collects (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, 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 flow rate of the river based on (1). By separately providing a configuration (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 system, and the accumulation and sharing of surveying results can be performed more smoothly.

[0013] In addition, the unmanned aerial vehicle preferably includes a rotor as a thrust source for moving through the air, and a water propulsion device as a thrust source for moving 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 area is 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] In this case, the unmanned aerial vehicle preferably includes a control device and a distance measuring sensor directed from the body to the side, 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 equal to or smaller than a predetermined distance. In this case, the unmanned aerial vehicle preferably includes a control device, and the control device automatically operates the water propulsion device so that the unmanned aerial vehicle traveling down the river on the water current moves along a route on a pre-specified longitude and latitude. In this case, the scanner device is a multi-beam echo sounding device, and the control device automatically operates the water propulsion device so that the sonar array direction of the multi-beam echo sounding device is maintained in a direction intersecting with the traveling direction. In this case, the unmanned aerial vehicle preferably includes a control device, and the control device preferably includes a flight detouring means for automatically taking off and flying when the unmanned aerial vehicle traveling down the river on the water current reaches a predetermined position, and landing on water at another position further downstream than that position. These autopilot functions reduce the piloting skills required of the pilot and enable more accurate surveying outside visual line of sight.

[0016] It is also preferable that the unmanned aerial vehicle is equipped with a pair of pontoon-shaped floats, and that the water propulsion device is disposed closer to the center of the aircraft body than the pair of floats when the unmanned aerial vehicle is viewed from above. It is also preferable that the unmanned aerial vehicle is equipped with a three-body float, and that the scanner device is disposed in a recess provided in the bottom of the central float. This makes it possible to protect the water propulsion device and the scanner device from collisions with floating objects on the water surface and surrounding objects, making it possible to carry out surveying more safely.

[0017] In order 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 the upstream to the downstream of the river. In this case, the river surveying method of the present invention may include a step of automatically taking off and flying the unmanned aerial vehicle when the unmanned aerial vehicle descends the river to a predetermined position, and landing on another position further downstream than that position. The effects and principles 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 different positions in the river width direction and floating them on the water current of the river from the upstream to the downstream, thereby shortening the time required to survey a wide water area.

[0019] The river survey method of the present invention may also include a step of flying the unmanned aerial vehicle down the river to a predetermined position, and 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 state of a specific part of the river during flooding or flooding, it is possible to discover and understand phenomena that occur only under specific conditions. Effect 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, oceans, dams, lakes, etc., it is possible to carry out this surveying more easily and with greater accuracy. [Brief description of the drawings]

[0021] [Figure 1] FIG. 2 is a perspective view of the multicopter 12. [Diagram 2] FIG. 2 is a bottom view of the multicopter 12. [Diagram 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. [Diagram 5] FIG. 1 is a schematic diagram showing how a 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] FIG. 1 is a schematic diagram showing a multicopter 12 riding the water current of a river and descending the river. [Figure 8] This is a schematic diagram showing a state in which multiple multicopters 12 ride the water current of a river and go 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 survey system 10 is used not for a river but for a natural dam ND with a still water surface. [Figure 11] FIG. 2 is a bottom view showing a modified example of the multicopter 12. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of the present invention will be described 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, is floated on the water surface and the altitude acquired by its GPS (Global Positioning System) 31 is RTK corrected to obtain a relatively accurate water level with little effort and constraints. This feature and other associated features will be described below through the embodiment. 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 scope of "surveying" defined in the Surveying Act. Also, "water level" is also called "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. Below, an overview of the surveying system 10 will be described with reference to Figs. 1 to 3.

[0024] As shown in Fig. 1 and Fig. 2, the multicopter 12 of this embodiment is a so-called hexacopter in which the rotors 12 are fixed to the tips of six arms extending radially in a plan view. The multicopter 12 is provided with a pair of pontoon-shaped floats 50 for floating the aircraft on the water surface, and a pair of thrusters 42 for moving the multicopter 12 on the water surface is fixed to each float 50. 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 a 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 is connected to the multicopter 12 and the multibeam sonar 13 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 while checking the detection values ​​of the sensors connected to the FC / BC 20 in response to various autopilot programs described later and instructions from the operator 19, and causes the multicopter 12 to fly and navigate. In the surveying system 10 of this embodiment, the multicopter 12 is provided with the thrusters 42, thereby improving 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 provided with six rotors 41 as thrust sources for moving in the air and two thrusters 42 as thrust sources for moving on the water surface, and the FC / BC 20 can switch between a "flight mode" for moving in the air with the rotors 41 and a "navigation mode" for moving on the water surface with the thrusters 42 automatically or by instructions from the operator 19. The operator 19 remotely controls the multicopter 12 by visual control when the multicopter 12 is within visual range, and by relying on images transmitted from the camera 39 when the multicopter 12 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 for correcting 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 a service on the Internet through an LTE (Long Term Evolution) line. As a result, in the surveying system 10 in this embodiment, it is not necessary to install an RTK base station (fixed station) around the survey point each time, and the constraint on the distance between the RTK receiver 32 and each RTK base station is also relaxed, making it possible to carry out a quicker, simpler, and more extensive survey. The RTK receiver 32 may use other mobile communication networks such as 5G, 3G, and WiMAX (Worldwide Interoperability for Microwave Access) in addition to the LTE line. In this embodiment, the GPS is used as the GNSS device, but this may be a receiver such as GLONASS, Galileo, Michibiki (quasi-zenith satellite system), or COMPASS (Hokuto satellite positioning system).

[0029] Here, the FC / BC 20 of this embodiment can continue to obtain altitude from the GPS 31 and correction information from the RTK receiver 32 even after the rotor 41 has stopped. As described above, a typical unmanned aerial vehicle uses GPS exclusively to obtain longitude and latitude, and obtains altitude during flight using an air pressure sensor built into the flight controller and a distance measurement sensor facing downward. In other words, the altitude output by the GPS is not basically used even during flight, much less 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 obtain water levels, so they need to continue operating 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 to acquire point cloud data around the body. The output data of the LiDAR 38 is input to a Simultaneous Localization and Mapping (SLAM) program 231 (described later), and the positional relationship between the body and its surrounding objects is identified.

[0031] (Multi-beam sonar) The multi-beam sonar 13 is a multi-beam echo sounding device that transmits sound beams of different frequencies in a fan shape into the water and receives the reflected waves to obtain river topography data. The multi-beam 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 is a unit equipped with a transmitter in which multiple sonars are arranged, a receiver for receiving reflected waves, a dedicated IMU, a surface sound speed meter, and the like. The GPS 31 is the same as that used by the FC / BC 20 of the multicopter 12. The control unit 60 is a device for operating the operation and settings of the sonar unit 70, correcting the inclination of the point cloud data acquired by the sonar unit 70, and recording and transferring the data acquired by the sonar unit 70. Measurement using ultrasonic waves is less affected by turbidity than optical cameras and green lasers, and more accurate topographical data can be obtained even under difficult conditions. The scanner device installed on the multicopter 12 is not limited to the multibeam sonar 13, as long as it can acquire underwater topographical data after the multicopter 12 lands on the water. For example, if only a highly transparent and still water area is to be surveyed, it is considered that topographical data can be acquired even with a scanner device using an optical camera or laser. In the following description, both the multicopter 12 and the multibeam sonar 13 will 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. In addition, the function of the data integration unit 11 may be provided in the operating terminal of the operator 19.

[0034] The data integration unit 11 of this embodiment acquires topographical data from the multi-beam sonar 13, and acquires from the multicopter 12 the altitude value of the GPS 31, the corrected altitude value obtained by correcting this altitude value with the correction information of 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 integration unit 11 also acquires the longitude and latitude and the time when the multicopter 12 and the multi-beam sonar 13 acquired these data, and calculates the flow velocity of the river. Note that the flow velocity of the river may be calculated by the multicopter 12 and transmitted to the data integration unit 11.

[0035] The data integration unit 11 calculates the flow rate of the river based on the topographical data and the flow velocity, and acquires or calculates the water surface elevation of the river, as will be described later in detail. In this way, the surveying system 10 of this embodiment is provided with a configuration (data integration unit 11) specialized for collecting and integrating data acquired by the multicopter 12 and each of its devices, so that the load and function of each device are appropriately distributed throughout the system. In addition, the data integration unit 11 serves as a hub to accumulate and share survey results. Note that an independent data integration unit 11 is not essential for the surveying system 10, and for example, the multicopter 12 may have a processing function 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 the longitude and latitude used for automatic piloting. However, if the RTK receiver 32 is used only to obtain the water surface elevation, the RTK receiver 32 may be placed in the data integrator 11, and the altitude value obtained by the GPS 31 may be corrected by the data integrator 11.

[0037] (Autopilot function) 4 is a block diagram showing the autopilot functions of the FC / BC 20. The multicopter 12 of this embodiment is provided with 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 as its autopilot functions. Each of the autopilot functions of 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 a flight route, flight altitude at each waypoint, flight speed between each waypoint, etc.

[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 including parameters of a start point, an end point, and one or more waypoints that constitute a navigation route, which are specified on map data. The autonomous navigation program 22 automatically operates the thrusters 42 so that the multicopter 12, which rides the water current of the river and descends the river, 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 identifies the positional relationship between the body of 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 equal to or smaller than a predetermined distance and so that the multicopter 12 does not deviate from the navigation route as much as possible. The SLAM program 231 can also use a distance measurement sensor other than the LiDAR 38, such as one or more ultrasonic distance measurement sensors, laser distance measurement sensors, stereo cameras, depth cameras, millimeter wave radars, etc., as long as the distance measurement sensor is directed to the side (horizontal direction) of the body of the multicopter 12. 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 (nose) 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 in this embodiment automatically operates the thrusters 42 to maintain the sonar array direction of the multibeam sonar 13 in a direction that intersects (as perpendicular as possible) with the direction of travel along the navigation route of the cruise plan.

[0042] The flight detouring program 25 is a function that allows the multicopter 12, which rides the water current of the river down the river, to fly around structures that it cannot pass through, such as water intake dams and dams. When the multicopter 12 descends the river to a specified position, the flight detouring program 25 automatically causes the multicopter 12 to take off and fly, and land on another position further downstream than that position. In this embodiment, the takeoff point and landing point of the flight detouring program 25, the flight altitude between these two points, and the like are specified as waypoints of 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 in the river. When the multicopter 12 descends the river to a predetermined position, the fixed position observation program 26 automatically causes the multicopter 12 to take off and fly, land on another position upstream from that position, and let the multicopter 12 flow again in the river water flow. In this embodiment, the takeoff point and landing point of the fixed position observation program 26, the flight altitude between these two points, the number of repetitions or the repetition time, etc. are specified as waypoints of the cruise plan.

[0044] In this way, 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 of a certain level 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 water current of the river and moves down the river. Fig. 9 is a schematic diagram showing how the multicopter 12 repeatedly surveys a specific position range of the river. Hereinafter, a river surveying method using the surveying system 10 will be described with reference to Figs. 5 to 9.

[0046] When surveying a river using the survey 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 may fly or navigate to the starting point of the cruise plan. When the multicopter 12 is floated on the water surface SF, the FC / BC 20 switches the multicopter 12 from flight mode to navigation mode. As described above, the FC / BC 20 continues to operate the GPS 31 and the RTK receiver 32 even after switching the multicopter 12 to the navigation mode (after stopping the rotor 41). The multicopter 12 switched to the navigation mode starts scanning the water with the multibeam sonar 13. The multibeam sonar 13 transmits a sound beam in a fan shape over a set swath width θ to obtain point cloud data representing the topography of the river channel TP. If the swath width θ of the multibeam sonar 13 is set to 180° or more, the cross-sectional shape of the entire current water area can be obtained.

[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 certain cross section of a river in a specified 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 by the following formula. The flow velocity can be calculated from the longitude and latitude coordinates acquired by the GPS 31, their correction values, and the acquisition time. 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 the HQ curve (water level flow rate curve) derived from multiple flow rate measurements carried out in the past. However, the surveying system 10 of this embodiment can measure the actual flow rate and also 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 rate V obtained using a float or the like during a flood for each water level (H). Since the cross-sectional area A changes depending on the water level H, the HQ curve is an exponential curve. In river areas without a water level observation station, the water level H is calculated by back-calculating the flow rate Q at the position of the reference observation station using the cross-sectional area A, but 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 state. The surveying system 10 of this embodiment can calculate the flow rate Q based on the cross-sectional area A and flow rate V measured during a flood, and compare the result with the measured water level H.

[0048] As shown in FIG. 7, the multicopter 12 floating on the river RV rides the water current and descends the river. The autonomous navigation program 22 automatically operates the thrusters 42 so that the multicopter 12 descends the river 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 also controls the heading direction so that the sonar array direction of the multibeam sonar 13 is maintained as intersecting with the traveling direction of the navigation route R1 as much as possible. When the multicopter 12 descends the river to the designated position, the flight detouring program 25 flies around the intake weir S1, which is an inaccessible structure located in the middle of the navigation route R1 (R2). The SLAM program 231 detects a bridge pier S2 located on the navigation route R1, and the collision avoidance program 23 passes through it with the minimum deviation required (R4).

[0049] Here, the flow speed of a river may differ depending on the position in the river width direction. For example, even in a place where the river flows in a straight line, in a deep area, the flow speed in the center of the river is faster than the flow speed on both sides due to the influence of two spiral currents aligned in the river width direction. Also, when the water volume of the river increases, the water level in the center of the river increases, and a flow from the center to both sides occurs on the water surface. Conversely, when the water volume of the river decreases, the water level in the center of the river decreases, and a flow from both sides to the center occurs on the water surface. Also, in an area where the river is curved, the flow speed on the outside of the curved part is faster than the flow speed on the inside. And, if a floating object in deep water faces the direction where the flow speed is the fastest, it will naturally be guided to the direction where the flow speed is faster. Therefore, if it is sufficient to let the multicopter 12 flow along the course with the fastest flow speed in the river, it is considered that the longitude and latitude values ​​specified for the autopilot function are sufficient as long as they are accurate enough to circumvent obstacles such as bridges.

[0050] As shown in Fig. 8, in the case of a large river, multiple multicopters 12 may be arranged at different positions in the river width direction and each may be floated along the water flow of the river. This can shorten the time required to survey a large river. Also, scanning the terrain with two multibeam sonars 13 with narrower swath widths can reduce the number of blocked areas where the beams do not reach, such as so-called occlusion areas and shadow areas, rather than setting a wide swath width of one multibeam sonar 13.

[0051] Also, as shown in FIG. 9, when investigating changes over time in scouring and deepening near the 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 bridge pier S1 and then flown down the river while scanning again (R5). This is repeated the number of times or for the 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 in which the surveying system 10 is used not for a river but for a natural dam ND with a still water surface. The surveying system 10 can be used not only for rivers with water flow, but also for water areas with a still water surface. The multicopter 12 in FIG. 10 flies and moves automatically or manually to the point where the natural dam ND is generated, and lands on the water surface of the target natural dam ND. Then, the thruster 42 is operated automatically or manually to obtain the topographical data and water surface elevation of the natural dam ND. For example, the multicopter 12 is stopped at a point on the water surface, and the aircraft is rotated in a circumferential direction while scanning the topographical data with the multibeam sonar 13, so that 3D data of the topography can be easily obtained.

[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 (from below), the thrusters 42 are arranged on the outer side of the pair of floats 50, but in the multicopter 12a of FIG. 11(a), the thrusters 42 are arranged closer to the center of the aircraft than the floats 50. This makes it possible to protect the thrusters 42 from collisions with floating objects and surrounding objects. In the multicopter 12 of the above embodiment, the sonar unit 70 is fixed in an exposed state to the underside of the body 121 of the multicopter 12. On the other hand, the multicopter 12b of FIG. 11(b) has three-body floats 51 and 52, and the sonar unit 70 is arranged in a recess 521 provided in the bottom of the central float 52 between the side floats 51 on both sides. This makes it possible to protect the sonar unit 70 from collisions with floating objects and surrounding objects.

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

[0055] 10: Survey system, 11: Data integration unit, 12; 12a; 12b: Multicopter (unmanned aerial vehicle), 121: Body, 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 (distance measurement 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: water 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 a water surface and being carried by the water current of a river from upstream to downstream; 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; An RTK (Real Time Kinematic) device that acquires correction information for correcting the altitude value output by the GNSS device, The altitude value obtained after the unmanned aerial vehicle lands on water is used to calculate the elevation of the water surface. 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 includes: 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 / 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 includes: Calculating the flow rate of a river based on (1) above; The surveying system according to claim 7.

9. The unmanned aerial vehicle includes: A rotor that provides thrust for moving through the air; and a water propulsion device which 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 includes: 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 includes: A control device; A distance measurement sensor directed from the aircraft to the side thereof; 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 smaller 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 traveling down the river on the water current of 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 water propulsion device so as to maintain the sonar array direction of the multi-beam 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 the unmanned aerial vehicle, which rides on the water current of the river and descends the river, when the unmanned aerial vehicle reaches a predetermined position in the river, and landing on the 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 aerial vehicle is viewed from above. The surveying system according to claim 9.

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

Images