JP2022066942A - Measuring system and measuring method - Google Patents

Abstract

To measure a measuring object area such as a forest and the like by using an unmanned aircraft.SOLUTION: In a measuring system, measurement of a measuring object area is performed by flying an unmanned helicopter 1 in which a LiDAR sensor is provided. In a plan view viewed from a vertical direction 33, when an airframe travelling direction of the unmanned helicopter 1 is defined as a first direction 31, and a direction vertical to the first direction 31 is defined as a second direction 32, during the measurement of the measuring object area using the LiDAR sensor, the unmanned helicopter 1 flies in a state where a rotary shaft direction 21a of the LiDAR sensor faces the direction closer to the second direction 32 than the first direction 31.SELECTED DRAWING: Figure 5

Description

The present invention relates to a technique for measuring a measurement target area using an unmanned aerial vehicle and the like.

Forest inventory is being carried out to manage and utilize forest resources. Forest measurement can be performed by various methods. For example, Patent Document 1 discloses a method of photographing a forest with a camera from the sky and extracting a canopy circle from the obtained image by image processing. Patent Document 2 irradiates a forest with radar waves having different wavelengths from the sky, and determines the height of the tree from the difference in height calculated from the reflected wave from the top of the tree and the reflected wave from the ground. Disclose the method of request. Patent Document 3 discloses a method in which a laser ranging device is mounted on an aircraft and the laser ranging device is used to acquire three-dimensional data on the ground including trees and the like.

JP-A-2007-66050 Japanese Unexamined Patent Publication No. 9-184880 Japanese Unexamined Patent Publication No. 2016-70708

When forest measurement is performed from the sky using a laser ranging device, point cloud data, which is data on the upper surface of the forest (upper surface of the canopy), can be obtained. However, it is difficult to acquire trunk data because the laser beam is blocked by the leaves of trees and the like. Therefore, it was necessary to estimate the number of main trunks, which are the thickest trunks, from the measurement results.

In Patent Document 3, a human brings a device such as a laser ranging device into a forest, further acquires three-dimensional point cloud data, and obtains point cloud data obtained by measurement from the sky and measurement on the ground. It is mentioned to fuse with the point cloud data. However, it is very troublesome to acquire two types of point cloud data.

It is required to measure the measurement target area such as forests using an unmanned aerial vehicle.

The measurement system according to an embodiment of the present invention is a measurement system for flying an unmanned aerial vehicle provided with a lidar (LiDAR) sensor to measure an area to be measured, and is provided for the unmanned aerial vehicle and the unmanned aerial vehicle. It is equipped with a rider sensor and a control device that controls the flight of the unmanned aerial vehicle. When the second direction is set, during the measurement of the measurement target area using the rider sensor, the unmanned aerial vehicle is in a state where the rotation axis of the rider sensor faces a direction closer to the second direction than the first direction. Fly with.

During the measurement of the measurement target area using the rider sensor, the unmanned aerial vehicle flies in a state where the rotation axis of the rider sensor faces a direction closer to the second direction than the first direction. Since the rider sensor is rotating, it is possible to densely irradiate the area along the traveling direction of the aircraft with a laser pulse while the unmanned aerial vehicle is traveling. Thereby, for example, in the form in which a plurality of laser pulses are simultaneously emitted from the lidar sensor, the same object in the area along the traveling direction of the aircraft can be densely irradiated with the laser pulses from various angles. As a result, detailed three-dimensional point cloud data of the area along the traveling direction of the aircraft can be acquired. Further, by rotating the rider sensor, for example, the trees constituting the forest can be irradiated with the laser pulse from various angles.

In the flight of one path segment included in the flight path, the area along the traveling direction of the aircraft can be repeatedly irradiated with the laser pulse. This makes it possible to acquire high-density 3D point cloud data in the flight of that one path segment.

It is possible to acquire high-density 3D point cloud data of the area scanned by the rider sensor in the flight of one route segment without having to scan the area in detail again in the flight of another route segment.

The same object in the measurement target area can be continuously irradiated with a laser pulse. As a result, for example, when measuring while flying over a tree, the geographic coordinates between the point cloud data obtained by measuring while approaching the tree and the point cloud data obtained by measuring while moving away from the tree. The misalignment on the system can be reduced.

In certain embodiments, the rider sensor may have its rotation axis oriented in a direction closer to the left-right direction than the front-rear direction of the airframe of the unmanned aerial vehicle.

In the normal flight posture of an unmanned aerial vehicle in which the front-rear direction of the aircraft faces the traveling direction of the aircraft, the rotation axis of the rider sensor can be oriented in a direction closer to the second direction than the first direction.

In one embodiment, during the measurement of the measurement target area using the rider sensor, the control device so that the rotation axis of the rider sensor faces a direction closer to the second direction than the first direction. The unmanned aerial vehicle may be flown.

Even if the rotation axis of the rider sensor is not oriented closer to the left-right direction than the front-back direction of the unmanned aerial vehicle, the unmanned aerial vehicle can be flown with the rotation axis oriented toward the second direction. can.

In certain embodiments, the axis of rotation of the rider sensor may be oriented in the second direction during measurement of the measurement target area.

As the unmanned aerial vehicle travels, the laser pulse can be applied more densely to the area along the traveling direction of the aircraft. As a result, more detailed three-dimensional point cloud data of the area along the traveling direction of the aircraft can be acquired. Further, by rotating the rider sensor, for example, the trees constituting the forest can be irradiated with the laser pulse from various angles.

In certain embodiments, the axis of rotation of the rider sensor may be tilted with respect to the second direction in the plan view during measurement of the measurement target area.

The irradiation position of the laser pulse formed on the ground by the lidar sensor can be expanded and distributed in the second direction. When the scan line uses one rider sensor, the irradiation position is located on a straight line parallel to the first direction when the rotation axes coincide with the second direction. By expanding the irradiation position of the laser pulse in the second direction, the irradiation leakage region can be reduced.

In certain embodiments, the lidar sensor may emit a laser pulse in a direction having a predetermined angle with respect to the axis of rotation, and may rotate the direction in which the laser pulse is emitted around the axis of rotation.

When a rider sensor having one scan line is used, the irradiation positions of the laser pulses formed on the ground are lined up on one line, but it is possible to scan an area having a width in the second direction.

In certain embodiments, the measurement target area may include a forest in which a plurality of trees rise from the ground surface.

The forest can be irradiated with laser pulses from various angles, and the laser pulses reach and are reflected not only on the canopy of the tree, but also on the trunk of the tree, understory vegetation and the ground surface. As a result, it is possible to obtain three-dimensional point cloud data including not only the canopy point cloud but also the trunk point cloud, the understory vegetation point cloud and the ground surface point cloud.

In certain embodiments, the ground surface includes a slope, and during measurement of the measurement target area, the control device may raise or lower the unmanned aerial vehicle along the slope.

It is possible to irradiate the forest spreading on the slope not only from the diagonally upward direction but also from the lateral direction, or to irradiate the laser pulse from the diagonally downward direction. The laser pulse reaches and is reflected not only on the canopy of the tree but also on the trunk of the tree, understory vegetation, and the ground surface. As a result, it is possible to obtain three-dimensional point cloud data including not only the canopy point cloud but also the trunk point cloud, the understory vegetation point cloud and the ground surface point cloud.

In certain embodiments, during the measurement of the area to be measured, the control device may fly the unmanned aerial vehicle along a first path segment that crosses a plurality of contour lines.

By flying an unmanned aerial vehicle along the slope so as to cross multiple contour lines, the forest spreading on the slope can be irradiated with a laser pulse not only from diagonally above but also from the side, or from diagonally below. It is possible to irradiate a pulse.

In certain embodiments, during the measurement of the measurement target area, the control device may fly the unmanned aerial vehicle with the rotation axis of the rider sensor oriented in a direction along a contour line.

When an unmanned aerial vehicle flies along a slope with the axis of rotation of the rider sensor pointing in the direction along the contour line, a laser pulse is emitted not only from diagonally upward but also from the side to the forest spreading on the slope. It can be irradiated or a laser pulse can be irradiated from diagonally downward.

In certain embodiments, the flight path through which the unmanned aerial vehicle flies when measuring the measurement target area may include a second path segment that intersects the first path segment in the plan view.

By flying a plurality of path segments that intersect each other, it is possible to irradiate the measurement target area with laser pulses from a plurality of directions, and it is possible to acquire detailed three-dimensional point cloud data of the measurement target area.

In certain embodiments, the flight path for flying the unmanned aerial vehicle when measuring the measurement target area may include a grid-like flight path.

By flying in a grid-like flight path, it is possible to irradiate the measurement target area with laser pulses from a plurality of directions, and it is possible to acquire detailed three-dimensional point cloud data of the measurement target area.

In one embodiment, a second rider sensor is provided in the unmanned aerial vehicle in addition to the rider sensor, and in the plan view, the rotation axis of the second rider sensor is different from the rotation axis of the rider sensor. It may be facing in the direction.

By emitting laser pulses from two rider sensors whose rotation axes are oriented in different directions, it is possible to irradiate a larger range of laser pulses.

In one embodiment, during the measurement of the measurement target area, the rotation axis of the second rider sensor is oriented in a direction closer to the second direction than the first direction in the plan view, and the aircraft advances. When the direction is the forward direction, the rotation axis of the rider sensor faces diagonally from the front left to the diagonally rear right, and the rotation axis of the second rider sensor faces diagonally from the front right to the diagonally rear left. good.

It is possible to irradiate more laser pulses to the area along the traveling direction of the aircraft. Further, since the two rider sensors emit laser pulses in different directions, the area where it is difficult to irradiate many laser pulses from one rider sensor can be complemented by the other rider sensor.

In a certain embodiment, during the measurement of the measurement target area, the rotation axis of the second rider sensor may be oriented in a direction closer to the first direction than the second direction in the plan view.

It is possible to irradiate a laser pulse over a wide range in the lateral direction with respect to the traveling direction of the aircraft.

In certain embodiments, the unmanned aerial vehicle may be an unmanned helicopter or an unmanned multicopter powered by an internal combustion engine.

When an electric motor operated by electric power supplied from a battery is used as a power source, the cruising range is short and the measurement target area is narrowed. On the other hand, when an internal combustion engine is used as a power source, a sufficient measurement target area can be secured because the cruising range is long.

The measurement of the measurement target area according to the embodiment of the present invention is a method of flying an unmanned aerial vehicle provided with a lidar (LiDAR) sensor to measure the measurement target area, and is a method of measuring the measurement target area. To fly the unmanned aerial vehicle along the set flight path, and in a plan view seen from the vertical direction, the aircraft traveling direction of the unmanned aerial vehicle is set as the first direction, and it is perpendicular to the first direction. When the direction is the second direction, the rider sensor scans the measurement target area in a state where the rotation axis of the rider sensor faces a direction closer to the second direction than the first direction. do.

During the measurement of the measurement target area using the rider sensor, the unmanned aerial vehicle flies in a state where the rotation axis of the rider sensor faces a direction closer to the second direction than the first direction. Since the rider sensor is rotating, it is possible to densely irradiate the area along the traveling direction of the aircraft with a laser pulse while the unmanned aerial vehicle is traveling. Thereby, for example, in the form in which a plurality of laser pulses are simultaneously emitted from the lidar sensor, the same object in the area along the traveling direction of the aircraft can be densely irradiated with the laser pulses from various angles. As a result, detailed three-dimensional point cloud data of the area along the traveling direction of the aircraft can be acquired. Further, by rotating the rider sensor, for example, the trees constituting the forest can be irradiated with the laser pulse from various angles.

In the flight of one path segment included in the flight path, the area along the traveling direction of the aircraft can be repeatedly irradiated with the laser pulse. This makes it possible to acquire high-density 3D point cloud data in the flight of that one path segment.

It is possible to acquire high-density 3D point cloud data of the area scanned by the rider sensor in the flight of one route segment without having to scan the area in detail again in the flight of another route segment.

The same object in the measurement target area can be continuously irradiated with a laser pulse. As a result, for example, when measuring while flying over a tree, the geographic coordinates between the point cloud data obtained by measuring while approaching the tree and the point cloud data obtained by measuring while moving away from the tree. The misalignment on the system can be reduced.

In one embodiment, the flight path comprises a plurality of path segments, and the method combines each of the plurality of path segments with sensor data output from the rider sensor to generate three-dimensional point cloud data. You may do that further.

It is possible to acquire high-density 3D point cloud data of the area scanned by the rider sensor in the flight of one route segment without having to scan the area in detail again in the flight of another route segment. Therefore, it is possible to acquire high-density three-dimensional point cloud data of the measurement target area.

In one embodiment, the measurement target area includes a forest on a slope, and the step of setting the flight path of the unmanned aerial vehicle refers to the contour data in the target area and includes a flight path including a route segment that crosses a plurality of contour lines. May include setting.

By flying an unmanned aerial vehicle along the slope so as to cross multiple contour lines, the forest spreading on the slope can be irradiated with a laser pulse not only from diagonally above but also from the side, or from diagonally below. It is possible to irradiate a pulse. The laser pulse reaches and is reflected not only on the canopy of the tree but also on the trunk of the tree, understory vegetation, and the ground surface. As a result, it is possible to obtain three-dimensional point cloud data including not only the canopy point cloud but also the trunk point cloud, the understory vegetation point cloud and the ground surface point cloud.

In the plan view seen from the vertical direction, when the traveling direction of the unmanned aircraft is the first direction and the direction perpendicular to the first direction is the second direction, the rider sensor is measuring the measurement target area using the rider sensor. The unmanned aircraft flies with its axis of rotation oriented closer to the second direction than the first direction. Since the rider sensor is rotating, it is possible to densely irradiate the area along the traveling direction of the aircraft with a laser pulse while the unmanned aerial vehicle is traveling. Thereby, for example, in the form in which a plurality of laser pulses are simultaneously emitted from the lidar sensor, the same object in the area along the traveling direction of the aircraft can be densely irradiated with the laser pulses from various angles. As a result, detailed three-dimensional point cloud data of the area along the traveling direction of the aircraft can be acquired. Further, by rotating the rider sensor, for example, the trees constituting the forest can be irradiated with the laser pulse from various angles.

In the flight of one path segment included in the flight path, the area along the traveling direction of the aircraft can be repeatedly irradiated with the laser pulse. This makes it possible to acquire high-density 3D point cloud data in the flight of that one path segment.

It is possible to acquire high-density 3D point cloud data of the area scanned by the rider sensor in the flight of one route segment without having to scan the area in detail again in the flight of another route segment.

The same object in the measurement target area can be continuously irradiated with a laser pulse. As a result, for example, when measuring while flying over a tree, the geographic coordinates between the point cloud data obtained by measuring while approaching the tree and the point cloud data obtained by measuring while moving away from the tree. The misalignment on the system can be reduced.

It is a figure that the unmanned helicopter 1 which concerns on embodiment of this invention performs forest measurement. It is an external side view of the unmanned helicopter 1 provided with the LiDAR sensor 20 which concerns on embodiment of this invention. It is a front view of the unmanned helicopter 1 which concerns on embodiment of this invention. It is a figure which shows the hardware configuration example of the flight control box 15 which concerns on embodiment of this invention. It is a figure explaining the direction which the rotating shaft 21 of the LiDAR sensor 20 which concerns on embodiment of this invention faces. It is a figure which shows N laser pulses 22 which are simultaneously emitted from the LiDAR sensor 20 which concerns on embodiment of this invention. It is a figure which shows the laser pulse 22 emitted from the traveling unmanned helicopter 1 which concerns on embodiment of this invention. It is a figure explaining the direction which the rotating shaft 21 of the LiDAR sensor 20 which concerns on embodiment of this invention faces. It is a figure which shows the laser pulse 22 emitted from the traveling unmanned helicopter 1 which concerns on embodiment of this invention. It is a figure when the unmanned helicopter 1 which measures the measurement target area 50 which concerns on embodiment of this invention is seen from the left-right direction of an unmanned helicopter 1. It is a figure explaining the mode of flying in a state that the rotation shaft 21 of a LiDAR sensor 20 is directed in the traveling direction of an airframe, and measuring the forest. It is a figure which explains the forest measurement which concerns on embodiment of this invention, and irradiates a tree rising from a slope with a laser pulse 22. It is a figure which shows the measurement system 100 which includes the unmanned helicopter 1 and the tablet computer 70 which concerns on embodiment of this invention. It is a figure which shows the measurement system 100 which includes the unmanned helicopter 1 and the base station control apparatus 80 which concerns on embodiment of this invention. It is a figure which shows the hardware configuration example of the tablet computer 70 which concerns on embodiment of this invention. It is a flowchart which shows the procedure of the flight path setting processing which concerns on embodiment of this invention. It is a flowchart which shows the procedure of the flight operation of the unmanned helicopter 1 which set the flight path which concerns on embodiment of this invention. It is a figure which shows an example of the flight path 60 which concerns on embodiment of this invention. It is a figure explaining the direction which the rotating shaft 21 of a single LiDAR sensor 20 faces the scan line which concerns on embodiment of this invention. (A), (b) and (c) are diagrams showing a laser spot 24 formed on a plane by a laser pulse 22 emitted from a single LiDAR sensor 20 with a scan line according to an embodiment of the present invention. .. It is a figure which shows the laser spot 24 formed on the plane by the laser pulse 22 emitted from the traveling unmanned helicopter 1 which concerns on embodiment of this invention. It is a figure which shows the unmanned helicopter 1 which the rotating shaft 21 which concerns on embodiment of this invention faces the front-rear direction of an airframe. It is a front view of the unmanned helicopter 1 provided with a plurality of LiDAR sensors which concerns on embodiment of this invention. It is a figure explaining the direction which the rotating shaft 21, 41 of the LiDAR sensor 20, 40 which concerns on embodiment of this invention faces. It is a figure which shows the laser pulse 22, 42 emitted from the LiDAR sensor 20, 40 which concerns on embodiment of this invention. It is a figure which shows the laser pulse 22, 42 emitted from the traveling unmanned helicopter 1 which concerns on embodiment of this invention. It is a figure explaining the direction which the rotating shaft 21, 41 of the LiDAR sensor 20, 40 which concerns on embodiment of this invention faces.

In order to manage and utilize forest resources, it is important to carry out so-called “forest measurement”. This "forest measurement" may include surveying the structure of the forest, estimating the volume of the forest, and grasping the amount of change in the forest over a certain period of time. It takes a lot of manpower and time to measure each forest tree and perform various aggregation and analysis from the obtained data as in the conventional forest measurement. Therefore, it is being promoted to mount a laser ranging device (LiDAR sensor) on an unmanned aerial vehicle and perform forest measurement from the air using the LiDAR sensor.

Prior to describing embodiments of the present disclosure, definitions of terms used herein will be described.

<Terminology>
In the present specification, "forest measurement" includes scanning a forest from the sky using a LiDAR sensor and acquiring scan data. The scan data can typically be represented by the position coordinates of each point that constitutes a point cloud acquired for each scan. The position coordinates of the points obtained for each scan are defined by the local coordinate system that travels with the unmanned aerial vehicle. Such a local coordinate system may be referred to as a mobile coordinate system or a sensor coordinate system. In general, "forest inventory" involves converting the position of each reflection point represented in the local coordinate system into a geographic coordinate system. "Forest measurement" further analyzes the structure of the forest after conversion to the geographic coordinate system, visually displays the shape of the forest and trees, and determines the abundance ratio of each type of tree in the forest. It may include finding the volume density of the forest.

An "unmanned aerial vehicle" (UAV) is an aircraft that a person as a pilot does not board, and is sometimes called a drone. Aircraft may include rotary and fixed wing aircraft. An example of an unmanned aerial vehicle with rotors is an unmanned helicopter or an unmanned multicopter. The rotor blades may be rotated by an engine (internal combustion engine) or by an electric motor. The flight of an unmanned aerial vehicle may be an autonomous flight by a computer program, a semi-autonomous flight that partially automates, or a remote-controlled flight by a person using radio. The unmanned aerial vehicle can fly while measuring the current position three-dimensionally and correcting the position by using GNSS (Global Navigation Satellite System). In the exemplary embodiment described below, the "unmanned aerial vehicle" is an "unmanned helicopter."

The term "unmanned" means that no one needs to be on board to fly the aircraft, and does not exclude unmanned aerial vehicles carrying non-operators.

A "contour line" is a curve that connects points at equal heights above the standard sea level to accurately represent the undulations of the land on a map. In Japan, the height is measured with the average sea level of Tokyo Bay as the standard sea level (0 m). The height above the standard sea level is called "elevation". For example, on a map of Japan, a main curve is drawn every 10 m above sea level and a total curve is drawn every 50 m depending on the scale. However, in the present specification, the "contour line" may be a curve connecting points at the same height from the standard sea level, and includes a curve not shown on the map. For example, a curve connecting points at an altitude of 563 m can also be contour lines.

Further herein, the "contour line" includes a hypothetical curve connecting positions equal to the standard sea level on the actual terrain. The "equal height from the standard sea level" here does not have to be exact. For example, a hypothetical curve connecting positions at heights within ± 30 meters of "equal heights from the standard sea level" can also be contour lines.

"Absolute altitude" refers to the distance from the ground surface or water surface to the aircraft, and may also be expressed as "AGL" (Above Ground Level). When an aircraft is flying in a mountainous area, the vertical distance from the surface of the mountain to the aircraft is "absolute altitude". The "absolute altitude" is generally a value measured using a radio altimeter, but the present specification includes adopting a value measured using a LiDAR (rider) sensor as an absolute altitude. Also, in the present specification, "absolute altitude" includes, for example, a distance from a surface layer represented by a digital surface model or a DSM (Digital Surface Model). That is, when the absolute altitude is H meters, the distance measured from the ground surface may be H meters, or the distance measured from the surface layer of the canopy may be H meters.

Hereinafter, embodiments of measurement of the measurement target area according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an unmanned helicopter 1 that measures the measurement target area 50. In the example shown in FIG. 1, the forest 54 spreading on the slope 52 of the mountain is set as the measurement target area 50, and the forest measurement is performed using the unmanned helicopter 1. In the forest 54, a plurality of trees are rising from the ground surface. The forest 54 as the measurement target area 50 is not limited to the slope forest (slope forest), and may be a flat land forest. The measurement target area 50 is not limited to the forest, and may be, for example, an urban area. In the following illustration of the exemplary embodiment, the measurement target area 50 is the forest 54.

FIG. 2 is an external side view of an unmanned helicopter 1 provided with a LiDAR sensor (rider sensor) 20. FIG. 3 is a front view of the unmanned helicopter 1.

The LiDAR sensor 20 emits laser beam pulses (hereinafter abbreviated as "laser pulse") 22 one after another while changing the emission direction, and each is based on the time difference between the emission time and the time when the reflected pulse of each laser pulse is acquired. The distance to the position of the reflection point can be measured. The "reflection point" can be the canopy and trunk of each tree constituting the forest 54 and the ground surface such as slopes and flat lands.

The LiDAR sensor 20 can measure the distance from the flying object to the forest by any method. Examples of the measurement method of the LiDAR sensor 20 include a mechanical rotation method, a MEMS method, and a phased array method. These measurement methods differ in the method of emitting a laser pulse (scanning method). For example, a mechanical rotation type LiDAR sensor rotates a tubular head that emits a laser pulse and detects reflected light of the laser pulse, and scans a measurement object 360 degrees around the rotation axis in all directions. The MEMS type LiDAR sensor swings the emission direction of the laser pulse by using a MEMS mirror, and scans a measurement object within a predetermined angle range about the swing axis. The phased array type LiDAR sensor controls the phase of light to swing the emission direction of light, and scans a measurement object within a predetermined angle range about a swing axis.

The unmanned helicopter 1 includes an airframe 4 having a main body 2 and a tail body 3. A LiDAR sensor 20 is attached to the lower part on the front side of the machine body 4 via a bracket 25. A main rotor 5 is provided on the upper portion of the main body 2, and a tail rotor 6 is provided on the rear portion of the tail body 3. A radiator 7 is provided at the front portion of the main body 2. A flight control box 15 is provided at the rear of the main body 2. An engine 8 which is an internal combustion engine and a power generation device 9 are provided in the main body 2. Further, the intake system, the main rotor shaft, and the fuel tank (not shown) are housed in the main body 2. The rotation generated by the engine 8 is transmitted to the main rotor 5 and the tail rotor 6, and the rotation of the main rotor 5 and the tail rotor 6 causes the unmanned helicopter 1 to fly.

A control panel 10 is provided on the upper rear side of the main body 2, and an indicator light 11 is provided on the lower rear side. The control panel 10 displays a checkpoint before flight, a self-check result, and the like. The display of the control panel 10 can also be confirmed by the ground station. The indicator light 11 displays the state of GNSS control, an abnormality warning of the aircraft, and the like. A skid 12, which is a leg that supports the aircraft 4 at the time of landing, is provided on the lower side of the center of the main body 2.

FIG. 4 shows a hardware configuration example of the flight control box (control device) 15. The flight control box 15 houses a GPS module 15a, an acceleration sensor 15b, a pressure sensor 15c, a geomagnetic sensor 15d, an ultrasonic sensor 15e, a communication circuit 15f, a signal processing circuit 15g, and a storage device 15j. The storage device 15j includes a ROM 15h, a RAM 15i, and the like. Each component may send and receive data to and from each other, for example via wiring or internal bus 15k. The position where various sensors such as the GPS module 15a are provided does not always have to be in the flight control box 15. For example, in order to facilitate the acquisition of signals from GPS satellites, the GPS module 15a may be provided on the upper part of the tail body 3.

The flight control box 15 includes a GPS module 15a as an example of the GNSS module. The GPS module 15a acquires flight data such as the current position and flight speed using GPS (Global Positioning System). The number of GPS modules 15a may be one or a plurality (for example, two). The acceleration sensor 15b is a three-axis acceleration sensor that detects acceleration in each of the X-axis, Y-axis, and Z-axis directions. If the acceleration sensor 15b is a six-axis acceleration sensor, it can further detect the roll acceleration, pitch angular velocity, and yaw acceleration of the unmanned helicopter 1. The acceleration sensor 15b may have a plurality of uniaxial acceleration sensors or biaxial acceleration sensors, and may be configured to detect each direction of the coordinate system XYZ by these uniaxial acceleration sensors or biaxial acceleration sensors. The barometric pressure sensor 15c detects barometric pressure. The current altitude can be known from the detected atmospheric pressure. Since the relational expression between the atmospheric pressure and the altitude is known, the description thereof is omitted in the present specification. The geomagnetic sensor 15d detects the current orientation of the unmanned helicopter 1. The ultrasonic sensor 15e is used to detect an absolute altitude during low-altitude flight. By using the data (airframe data) output from each of the acceleration sensor 15b and the geomagnetic sensor 15d, the current attitude of the unmanned helicopter 1 can be determined. Flight data and airframe data are provided to the signal processing circuit 15g.

The communication circuit 15f includes a communication circuit that performs wireless communication conforming to the Bluetooth® and / or Wi-Fi® standards. The communication circuit 15f may further perform wireless communication using a mobile phone line or a line via an artificial satellite. The communication circuit 15f receives flight path data before flight, and wirelessly performs necessary communication with the ground during flight. In the present embodiment, the flight route data includes the coordinates of the route to be flown by the unmanned helicopter 1 and the absolute altitude data.

The storage device 15j stores a computer program that controls the operation of the signal processing circuit 15g. The storage device 15j may store a computer program for causing the signal processing circuit 15g to control the flight of the unmanned helicopter 1 and the forest measurement described later. Such a computer program may be installed in the unmanned helicopter 1 from a recording medium (semiconductor memory, optical disk, etc.) on which it is recorded, or may be downloaded via a telecommunications line such as the Internet. Also, such a computer program may be installed on the unmanned helicopter 1 via wireless communication. Such computer programs may be sold as packaged software.

The signal processing circuit 15g executes a control program stored in the storage device 15j to fly the unmanned helicopter 1. More specifically, the signal processing circuit 15g monitors the above-mentioned flight data, aircraft data, operating state data such as engine rotation speed and throttle opening, and makes the unmanned helicopter 1 along a flight path prepared in advance. Let it fly.

In the example shown in FIG. 4, the flight control box 15 is connected to the LiDAR sensor 20. The LiDAR sensor 20 outputs a scan result (a set of time data, direction data, distance data, etc.) to the flight control box 15. Using the position data indicating the flight position of the unmanned helicopter 1 output from the GPS module 15a and the scan result output from the LiDAR sensor 20, for example, the position of the measurement object represented by the geographic coordinate system is calculated. Can be done.

The LiDAR sensor 20 may not be connected to the flight control box 15. For example, the GPS module 15a may be provided in the unmanned helicopter 1 independently of the flight control box 15, and position data may be output from the GPS module 15a to the flight control box 15 and the LiDAR sensor 20 respectively. In this case, the scan result of the LiDAR sensor 20 may be stored in a storage device (not shown) in the LiDAR sensor 20. If the signal processing circuit (not shown) in the LiDAR sensor 20 calculates the position of the object to be measured using the position data output by the GPS module 15a and the scan result of the LiDAR sensor 20, the position data is calculated. The calculation result may be stored in the storage device in the LiDAR sensor 20. The power supply may be shared between the flight control box 15 and the LiDAR sensor 20.

The operator who manages the flight and operation of the unmanned helicopter 1 can also fly the unmanned helicopter 1 along a flight path prepared in advance while visually observing the flight state. At the rear end of the tail body 3 (FIG. 2), a remote control receiving antenna 13 for receiving a command signal from the remote control controller is provided.

With reference to FIGS. 2 and 3, the LiDAR sensor 20 measures the distance to the reflection point by, for example, emitting (radiating) a near-infrared laser pulse 22 and detecting the reflected light of the laser pulse 22. It is an optical device.

In an exemplary embodiment, the LiDAR sensor 20 is of a mechanical rotation method, and the head 23 that emits the laser pulse 22 and detects the reflected light of the laser pulse 22 rotates about the rotation shaft 21. By rotating the head 23, it is possible to scan 360 degrees in all directions. In the present embodiment, the range of the scannable range of the LiDAR sensor 20 that is obstructed by the aircraft 4 or the like of the unmanned helicopter 1 is not reflected in the measurement result. For convenience of description, FIG. 2 shows only a part of the laser pulse 22 radiated in all directions of 360 degrees. In the present specification, the rotation of the head 23 of the LiDAR sensor 20 may be referred to as “rotation of the LiDAR sensor 20”.

The head 23 of the LiDAR sensor 20 changes the direction of the emission port by rotating, and simultaneously emits a plurality of laser pulses 22 at a predetermined angle pitch α (rad). FIG. 3 shows, as an example, N laser pulses 22 simultaneously emitted along a certain plane through which the rotation axis 21 of the LiDAR sensor 20 passes. For convenience of description, the laser pulse 22 is described in the form of a beam instead of the shape of a pulse. It should be noted that "simultaneous" does not have to be exactly the same time, and includes the fact that they are approximately the same time. The value of N is arbitrary and is, for example, 12, 16, 32 or 64, but N is not limited to these values. For example, N laser light sources are arranged in the head 23 of the LiDAR sensor 20, and the laser pulse 22 is emitted from the emission port of the N laser pulses 22. The laser light source is, for example, a laser diode, but is not limited to this.

The laser pulse 22 emitted from one exit port will be described with reference to FIG. 2. The head 23 of the LiDAR sensor 20 changes the direction of the exit port by rotating, emits a laser pulse 22 at a predetermined angle pitch α (rad), and detects the reflected light of each laser pulse 22 reflected in the forest. .. As a result, it is possible to obtain data on the distance to the reflection point in the direction for each predetermined angle pitch α. When the number of pulses emitted per unit time of the LiDAR sensor 20 is M and the rotation speed per unit time is R for one emission port, the predetermined angle pitch α is α (rad) = 2.π · R / M. Desired.

When N laser pulses 22 are simultaneously emitted from N emission ports, the LiDAR sensor 20 simultaneously emits N laser pulses 22 at predetermined angular pitch α.

The predetermined angle pitch α may be a fixed value or a variable value. The number of emission times M per unit time and the number of rotations R per unit time may also be fixed values or variable values.

Let N be the number of laser pulses emitted simultaneously in the same angular direction (FIG. 3). In an exemplary embodiment, when MN = 600,000 (pieces / sec), R = 10 (rotation / sec), and N = 16, the predetermined angle pitch α is about 0.0017 (rad), about 0. It is 096 degrees. However, for the sake of simplification of calculation, the scan range is set to 360 degrees.

As the LiDAR sensor 20, a LiDAR sensor that swings the emission direction of the laser pulse as described above and scans a measurement object within a predetermined angle range about the swing axis may be used. As used herein, the "rotation" and "rotation axis" of the LiDAR sensor 20 also include such "swing" and "swing axis". The rotation angle range when swinging the emission direction of the laser pulse is, for example, 180 degrees or less, but is not limited thereto.

Next, the direction in which the rotation axis 21 of the LiDAR sensor 20 faces in the exemplary embodiment will be described.

FIG. 5 is a diagram illustrating a direction in which the rotation axis 21 of the LiDAR sensor 20 faces. FIG. 5 shows an unmanned helicopter 1 in a plan view seen from the vertical direction 33. In a plan view seen from the vertical direction 33, the aircraft traveling direction of the unmanned helicopter 1 is the first direction 31, and the direction perpendicular to the first direction 31 is the second direction 32. In an exemplary embodiment, during measurement of the measurement target area 50 using the LiDAR sensor 20, in the unmanned helicopter 1, the rotation axis 21 of the LiDAR sensor 20 faces a direction closer to the second direction 32 than the first direction 31. Fly in the state. The angle θ formed by the rotation axis direction 21a and the second direction 32, which is the direction in which the rotation axis 21 faces, is, for example, 0 to 30 degrees, but is not limited thereto. As an example, the angle θ is 5 to 30 degrees. As another example, the angle θ is 20 to 30 degrees.

As shown in FIG. 5, in the LiDAR sensor 20, the rotation axis 21 may be oriented in a direction closer to the left-right direction than the front-rear direction of the body 4 of the unmanned helicopter 1. In the normal flight posture of the unmanned helicopter 1 in which the front-rear direction of the aircraft 4 faces the aircraft traveling direction (first direction 31), the rotation axis 21 of the LiDAR sensor 20 is oriented closer to the second direction 32 than the first direction 31. You can turn it.

FIG. 6 is a diagram showing N laser pulses 22 simultaneously emitted from the LiDAR sensor 20. As described with reference to FIGS. 2 and 3, the rotating head 23 of the LiDAR sensor 20 simultaneously emits N laser pulses 22 at a predetermined angular pitch α. FIG. 6 shows N laser pulses 22 emitted along a plane direction perpendicular to the vertical direction 33 among the laser pulses 22 emitted at each predetermined angular pitch α.

FIG. 7 is a diagram showing a laser pulse 22 emitted from an unmanned helicopter 1 traveling. For convenience of description, FIG. 7 shows the laser pulse 22 emitted along the plane direction perpendicular to the vertical direction 33 among the laser pulses 22 emitted at each predetermined angular pitch α. The flight distance that the unmanned helicopter 1 flies while the LiDAR sensor 20 makes one rotation is represented by J.

While the unmanned helicopter 1 travels a distance J, the LiDAR sensor 20 makes one rotation and emits N laser pulses 22 at a predetermined angle pitch α. At each of the rotation angles at which the laser pulses 22 are emitted, N laser pulses 22 are simultaneously emitted each time the unmanned helicopter 1 travels by a distance J. In this way, in the process of the unmanned helicopter 1 traveling, the laser pulse 22 can be densely irradiated to the area along the traveling direction of the aircraft (first direction 31). The same object (tree, etc.) in the area along the aircraft traveling direction 31 can be densely irradiated with the laser pulse 22 from various angles, and a detailed three-dimensional point cloud of the area along the aircraft traveling direction 31 can be applied. You can get the data.

FIG. 8 is a diagram showing a form in which the rotation axis 21 of the LiDAR sensor 20 faces the second direction 32 during the measurement of the measurement target area 50 using the LiDAR sensor 20. Similar to FIG. 6, FIG. 8 shows N laser pulses 22 emitted along a plane direction perpendicular to the vertical direction 33 among the laser pulses 22 emitted at predetermined angular pitch α. .. It should be noted that the rotating shaft 21 does not have to be exactly oriented in the second direction 32, and may be oriented substantially in the second direction 32.

FIG. 9 is a diagram showing a laser pulse 22 emitted from an unmanned helicopter 1 traveling in a form in which the rotation axis 21 of the LiDAR sensor 20 faces the second direction 32. For convenience of description, FIG. 9 shows the laser pulse 22 emitted along the plane direction perpendicular to the vertical direction 33 among the laser pulses 22 emitted at each predetermined angular pitch α.

As described with reference to FIG. 7, the LiDAR sensor 20 makes one rotation while the unmanned helicopter 1 travels a distance J, and emits N laser pulses 22 at a predetermined angle pitch α. At each of the rotation angles at which the laser pulses 22 are emitted, N laser pulses 22 are simultaneously emitted each time the unmanned helicopter 1 travels by a distance J. Even in the form in which the rotation axis 21 faces the second direction 32, the laser pulse 22 can be densely irradiated to the area along the aircraft traveling direction 31 in the process of the unmanned helicopter 1 traveling. The same object in the area along the aircraft traveling direction 31 can be densely irradiated with the laser pulse 22 from various angles, and detailed three-dimensional point cloud data of the area along the aircraft traveling direction 31 can be acquired. be able to.

As will be described later, the flight path for measuring the measurement target area 50 may include a large number of path segments. In the flight of one path segment included in the flight path, the area along the aircraft traveling direction 31 can be repeatedly irradiated with the laser pulse 22. This makes it possible to acquire high-density 3D point cloud data in the flight of that one path segment.

It is possible to acquire high-density 3D point cloud data in the area without having to scan the area scanned by the LiDAR sensor 20 in the flight of one route segment in detail again in the flight of another route segment.

FIG. 10 is a side view of the unmanned helicopter 1 that measures the measurement target area 50.

As described above, the LiDAR sensor 20 emits a laser pulse 22 at a predetermined angle pitch α. For convenience of explanation, FIG. 10 shows only some of those laser pulses 22. Specifically, FIG. 10 shows a laser pulse 22 emitted from the LiDAR sensor 20 in the forward diagonally downward direction, the direct downward direction, and the rear diagonally downward direction, respectively.

In the present embodiment, as shown in FIG. 10, after irradiating the measurement object such as the tree 56 with the laser pulse 22 while approaching, the laser pulse 22 is subsequently irradiated while moving away. Will be. As the unmanned helicopter 1 advances, the laser pulse 22 continuously irradiates the object to be measured. Since a plurality of measurements are continuously performed on a specific measurement object, it is possible to reduce the positional deviation on the geographic coordinate system between the point cloud data obtained by each measurement.

FIG. 11 shows, as a comparative example, measurement in a state where the rotation axis 21 of the LiDAR sensor 20 is oriented in the traveling direction of the machine body. The flight path 66 of the unmanned helicopter 1 includes route segments 66a and 66b.

The unmanned helicopter 1 measures, for example, a specific tree 57 in the process of traveling along the route segment 66a. Since the measurement target area has a certain area, the unmanned helicopter 1 continues to fly along the route segment 66a even after measuring the tree 57, and measures another measurement target. The unmanned helicopter 1 that has reached the end of the route segment 66a turns back and then travels along the route segment 66b. A predetermined distance is provided between the route segment 66a and the route segment 66b. The unmanned helicopter 1 measures the tree 57 again in the process of traveling along the route segment 66b. To acquire high-density three-dimensional point cloud data by combining the point cloud data obtained by measuring while traveling the route segment 66a and the point cloud data obtained by measuring while traveling the route segment 66b. Can be done.

However, since the unmanned helicopter 1 is flying a relatively long distance between the time when the tree 57 is measured while traveling along the route segment 66a and the time when the tree 57 is measured while traveling along the route segment 66b. , The cumulative error between them can appear as the coordinate deviation of the point cloud data.

For example, there is a method of detecting the position of an unmanned helicopter 1 by combining a GNSS and an inertial measurement unit (IMU). When trying to detect the position of the unmanned helicopter 1 with high accuracy, it is conceivable to perform interference positioning using the carrier phase using the GNSS (reference station) fixed to the reference point and the GNSS provided in the unmanned helicopter 1. Will be. However, in mountainous areas, radio waves from artificial satellites are easily blocked by steep slopes and tall trees, and it may be difficult to stably detect the position using only GNSS. During the period when GNSS cannot be used, the IMU is used to estimate the position and continue the flight. However, a cumulative error occurs in the coordinates detected by using the IMU, and the cumulative error increases in proportion to the flight distance.

Therefore, if the tree 57 is measured, then the tree 57 is measured again after flying a relatively long distance, the positional deviation on the geographic coordinate system between the point cloud data may become large. This misalignment causes, for example, an error in determining the diameter of the tree trunk.

On the other hand, as described above with reference to FIG. 10, in the present embodiment, the specific tree 56 can be continuously irradiated with the laser pulse 22. During a relatively short flight, measurements are taken while approaching a particular tree 56 and while moving away from that tree 56. It is possible to reduce the positional deviation on the geographic coordinate system between the point cloud data obtained by measuring while approaching a specific tree 56 and the point cloud data obtained by measuring while moving away from the tree 56. ..

As shown in FIG. 2, the LiDAR sensor 20 of the present embodiment can emit the laser pulse 22 in the forward direction and the forward diagonally upward direction. Therefore, it is possible to irradiate the measurement target area 50 not only from the diagonally upward direction but also from the lateral direction, or to irradiate the laser pulse 22 from the diagonally downward direction.

FIG. 12 is a diagram showing an unmanned helicopter 1 that performs forest measurement. In the example shown in FIG. 12, the forest 54 extends over the slope 52. The unmanned helicopter 1 measures the forest 54, which is the measurement target area, while ascending or descending along the slope 52.

The forest 54 spreading on the slope 52 can be irradiated with the laser pulse 22 not only from the diagonally upward direction but also from the lateral direction, or the laser pulse 22 can be irradiated from the diagonally downward direction. Irradiation of the laser pulse 22 from the lateral direction makes it easier for the laser pulse 22 to pass between the leaves that grow horizontally because it is basically exposed to sunlight. The laser pulse 22 reaches not only the canopy 56a of the tree 56 but also the trunk 56b of the tree 56, the understory vegetation 58, the ground surface 59, and the like, and is reflected. As a result, it is possible to obtain three-dimensional point cloud data including not only the canopy point cloud but also the trunk point cloud, the understory vegetation point cloud and the ground surface point cloud.

Next, a method of setting a flight path for flying an unmanned helicopter 1 in forest measurement will be described. The unmanned helicopter 1 is programmed to fly along a set flight path.

The operator can set the flight path by using a computer device such as a tablet computer or a base station control device. In the present specification, the unmanned helicopter 1 and such a computer device are collectively referred to as a "measurement system".

FIG. 13 shows an example of a measurement system 100 including an unmanned helicopter 1 and a tablet computer 70. FIG. 14 shows an example of a measurement system 100 including an unmanned helicopter 1 and a base station control device 80. Both the tablet computer 70 and the base station control device 80 have a built-in or external storage device, and the map data 90 is stored in the storage device. The tablet computer 70 and the base station control device 80 display the map data 90 on the display and receive the designation of the flight path 60 from the operator. The tablet computer 70 has a touch screen panel, and accepts the designation of the flight route to which the unmanned helicopter 1 should fly and the designation of the absolute altitude by the touch operation from the operator. It is assumed that the base station control device 80 according to the present embodiment is a notebook PC and supports the same touch operation as the tablet computer 70.

Hereinafter, the tablet computer 70 shown in FIG. 13 will be illustrated and described. The basic configuration of the tablet computer 70 and the basic configuration of the base station control device 80 are substantially the same. Therefore, the following description can be read as a description of the base station control device 80.

FIG. 15 shows a hardware configuration example of the tablet computer 70.

The tablet computer 70 includes a CPU 71, a memory 72, a communication circuit 73, an image processing circuit 74, a display 75, a touch screen panel 76, and a communication bus 77. The CPU 71, the memory 72, the communication circuit 73, the image processing circuit 74, and the touch screen panel 76 are connected by the communication bus 77, and data can be exchanged with each other via the communication bus 77.

The CPU 71 is a signal processing circuit (computer) that controls the operation of the tablet computer 70. Typically, the CPU 71 is a semiconductor integrated circuit. The CPU 71 may be simply referred to as a "processing circuit".

The memory 72 stores a computer program that controls the operation of the CPU 71. The memory 72 may store a computer program for causing the CPU 71 to control the forest measurement. The memory 72 may store a computer program for causing the CPU 71 to control the flight of the unmanned helicopter 1. Similar to the computer programs described above, such computer programs may be installed on the tablet computer 70 from the recording medium on which they are recorded, or may be downloaded via a telecommunication line such as the Internet. Further, such a computer program may be installed on the tablet computer 70 via wireless communication. Such computer programs may be sold as packaged software.

The memory 72 may be a volatile storage device (for example, RAM) for storing a computer program executed by the CPU 71, and a non-volatile storage device (for example, flash memory) for storing map data 90. The RAM can also be used as a work memory when the CPU 71 performs an operation. The computer program may be stored in flash memory. When the tablet computer 70 starts up, the CPU 71 reads a computer program from the flash memory, expands it into RAM, and executes it.

The communication circuit 73 is, for example, a wireless communication circuit that performs wireless communication conforming to the Bluetooth (registered trademark) and / or Wi-Fi (registered trademark) standard. Similar to the communication circuit 15f of the unmanned helicopter 1, in the present specification, the tablet computer 70 performs wireless communication conforming to the Bluetooth® standard and / or the Wi-Fi standard, and communicates with the unmanned helicopter 1 on a one-to-one basis. do. The communication circuit 73 receives data to be transmitted to the unmanned helicopter 1 from the CPU 71 via the communication bus 77. Further, the communication circuit 73 transmits the data received from the unmanned helicopter 1 (for example, the measurement result of the LiDAR sensor 20) to the CPU 71 and / or the memory 72 via the communication bus 77.

The image processing circuit 74 generates an image to be displayed on the display (display device) 75 according to the instruction of the CPU 71. For example, the image processing circuit 74 displays an image of the measurement target area 50 using the map data 90, and draws a flight path 60 on the display 75 in response to an operator's touch operation received via the touch screen panel 76. do.

The touch screen panel 76 can detect an operator's touch made with a finger, a pen, or the like. As the detection method, an electrostatic method, a resistance film type, an optical method, an ultrasonic method, an electromagnetic method and the like are known. For example, in the case of the capacitive touch screen panel 76, the touch screen panel 76 detects a change in capacitance at a specific position and transmits data related to the change to the CPU 71 via the communication bus 77. The CPU 71 determines whether or not there is a touch by the operator based on the transmitted data. An example of "data on change" is data on the position where the capacitance changed and the time length changed.

In this embodiment, the touch screen panel 76 is provided so as to be superimposed on the display 75. The operator performs a desired touch operation while looking at the image of the measurement target area 50 displayed on the display 75. The CPU 71 determines which position of the image displayed on the display 75 the detection position data output from the touch screen panel 76 indicates. In addition, instead of the touch screen panel 76, or together with the touch screen panel 76, another input device such as a mouse, a keyboard, a joystick, and a microphone may be provided.

Hereinafter, a method of setting a flight path using the tablet computer 70 of the measurement system 100 and a method of flying the unmanned helicopter 1 along the set flight path will be described.

FIG. 16 is a flowchart showing a procedure of flight path setting processing according to an exemplary embodiment. The procedure shown in FIG. 16 is executed under the control of the CPU 71 (FIG. 15) of the tablet computer 70 or the base station control device 80. When a plurality of measurement target areas can be selected, it is assumed that one of them is specified in advance.

In step S2, the CPU 71 acquires map data related to the measurement target area.

In step S4, the CPU 71 accepts the designation of the flight path 60 via the touch screen panel 76. Various methods for designating the flight path 60 can be considered. For example, the tablet computer 70 displays the measurement target area 50, the contour lines 62 of the measurement target area 50, and the flight path 60 calculated by the CPU 71. For example, the CPU 71 refers to the contour line data, calculates and displays the flight path 60 including the route segment crossing the plurality of contour lines 62. The operator can adjust the position of each route segment included in the flight route 60, the number of route segments, the distance between the route segments, and the like by an input operation such as a touch operation.

In step S6, the CPU 71 determines whether or not the setting of the flight path 60 is completed. For example, the CPU 71 repeats the processes of steps S4 and S6 on the assumption that the setting of the flight path 60 is not completed until the input indicating that the setting of the flight path 60 is completed is received from the operator. On the other hand, when the input indicating that the setting of the flight path 60 is completed is received, the CPU 71 determines that the setting of the flight path 60 is completed, and proceeds to step S8. In step S8, the CPU 71 accepts the absolute altitude designation via the touch screen panel 76. In FIG. 13, a “+” button for increasing the absolute altitude value and a “−” button for decreasing the absolute altitude value are displayed. It should be noted that the software keyboard may be displayed so that the numerical value can be directly input, or the numerical value may be input by using a GUI such as a dial or a slider.

By the above processing, the flight path 60 of the unmanned helicopter 1 is set. The data indicating the flight path 60 is, for example, wirelessly transmitted from the communication circuit 73 of the tablet computer 70 and received by the communication circuit 15f (FIG. 4) of the unmanned helicopter 1. The signal processing circuit 15g (FIG. 4) of the unmanned helicopter 1 stores the received data in the RAM 15i. After that, forest measurement is performed.

FIG. 17 is a flowchart showing the flight operation procedure of the unmanned helicopter 1 in which the flight path is set. The procedure shown in FIG. 15 is executed by controlling the signal processing circuit 15g of the unmanned helicopter 1.

In step S10, the signal processing circuit 15g of the unmanned helicopter 1 flies the unmanned helicopter 1 to the start position of the forest measurement while acquiring its own position by using the GPS module 15a or the like. The "start position" referred to here includes the absolute altitude in addition to the longitude and latitude of the position where the forest measurement on the flight path 60 is started. When the start position of the forest measurement is reached, in step S12, the signal processing circuit 15g starts the forest measurement using the LiDAR sensor 20.

In step S14, the signal processing circuit 15g flies the unmanned helicopter 1 along the set flight path 60 and at the set absolute altitude.

In step S16, the signal processing circuit 15g determines whether or not the forest measurement has been completed. Specifically, the signal processing circuit 15g determines whether or not the flight along the preset flight path 60 is completed. The processes of steps S14 and S16 are repeated until the forest measurement is completed.

When the forest measurement is completed, the unmanned helicopter 1 makes an autonomous flight, for example, and returns.

By combining the sensor data output from the LiDAR sensor 20 during flight for each of the plurality of path segments included in the flight path 60, high-density three-dimensional point cloud data can be generated. The process of generating high-density three-dimensional point cloud data may be executed by the tablet computer 70 or any other computer.

FIG. 18 is a diagram showing an example of the flight path 60.

In FIG. 18, a plurality of contour lines 62 are shown by broken lines. The flight path 60 includes a plurality of path segments that cross the plurality of contour lines 62. The plurality of route segments include a first route segment 60a and a second route segment 60b.

The signal processing circuit 15g (FIG. 4) of the unmanned helicopter 1 flies the unmanned helicopter 1 along a path segment that crosses a plurality of contour lines 62. During the measurement of the measurement target area 50, the signal processing circuit 15g flies the unmanned helicopter 1 with the rotation axis 21 of the LiDAR sensor 20 facing in the direction along the contour line 62. With reference to FIGS. 12 and 18, by flying the unmanned helicopter 1 along the slope 52 so as to cross the plurality of contour lines 62, the unmanned helicopter 1 is not only obliquely upward with respect to the forest 54 extending over the slope 52, but also from diagonally upward. The laser pulse 22 can be irradiated from the lateral direction, or the laser pulse 22 can be irradiated from the diagonally downward direction.

One path segment intersects several other path segments in plan view from the vertical direction 33. For example, in a plan view, the first path segment 60a intersects the second path segment 60b. By flying a plurality of path segments that intersect each other, the measurement target area 50 can be irradiated with the laser pulse 22 from a plurality of directions, and detailed three-dimensional point cloud data of the measurement target area 50 can be acquired. ..

The flight path 60 at which the path segments intersect with each other is a grid-like flight path. By flying along the grid-shaped flight path 60, the measurement target area 50 can be irradiated with the laser pulses 22 from a plurality of directions, and detailed three-dimensional point cloud data of the measurement target area 50 can be acquired.

Next, a mode in which the LiDAR sensor 20 having one scan line is provided in the unmanned helicopter 1 will be described.

The above-mentioned LiDAR sensor 20 has a plurality of scan lines, and simultaneously emits a plurality of laser pulses 22 at a predetermined angle pitch α. In the embodiment of the present invention, it is also possible to use the LiDAR sensor 20 having one scan line, which emits one laser pulse 22 for each predetermined angle pitch α. In such a LiDAR sensor 20, the measurable distance can be lengthened by increasing the output of the laser pulse 22.

FIG. 19 is a diagram illustrating a direction in which the rotation axis 21 of the LiDAR sensor 20 having a single scan line faces. FIG. 19 shows an unmanned helicopter 1 in a plan view seen from the vertical direction 33.

During the measurement of the measurement target area 50 using the LiDAR sensor 20, the rotation axis 21 of the LiDAR sensor 20 is tilted with respect to the second direction 32. In an exemplary embodiment, the angle θ between the rotation axis direction 21a and the second direction 32 is, but is not limited to, 20 to 40 degrees. For example, the angle θ may be 20 to 30 degrees.

The LiDAR sensor 20 emits a laser pulse 22 in a direction having a predetermined angle with respect to the rotation axis 21. For example, as shown in FIG. 19, the LiDAR sensor 20 emits a laser pulse 22 in a direction perpendicular to the rotation axis 21. The LiDAR sensor 20 rotates the direction in which the laser pulse 22 is emitted around the rotation axis 21.

FIG. 20 is a diagram showing a laser spot 24 formed in the measurement target area 50 by a laser pulse 22 emitted from a single LiDAR sensor 20 with a scan line. When the LiDAR sensor 20 having one scan line is used, the laser spots 24 formed in the measurement target area 50 are arranged on one line.

FIG. 20A shows a laser spot 24 formed on a plane while the LiDAR sensor 20 makes one rotation in a form in which the rotation axis direction 21a coincides with the second direction 32. When the rotation axis direction 21a coincides with the second direction 32, the laser spots 24 are aligned on a straight line parallel to the aircraft traveling direction (first direction 31).

20 (b) shows a laser spot 24 formed on a plane while the LiDAR sensor 20 makes one rotation in a form in which the rotation axis direction 21a is tilted with respect to the second direction 32 as shown in FIG. Is shown. When the rotation axis direction 21a is tilted with respect to the second direction 32, the laser spots 24 are aligned on a straight line tilted with respect to the aircraft traveling direction 31.

FIG. 20 (c) is a diagram showing a group of laser spots 24 arranged on two straight lines. While the unmanned helicopter 1 travels a distance J, the LiDAR sensor 20 makes one rotation, forming two groups of laser spots 24 arranged in a straight line.

FIG. 21 is a diagram showing a laser spot 24 formed on a plane by a laser pulse 22 emitted from an unmanned helicopter 1 traveling in a form in which the rotation axis direction 21a is tilted with respect to the second direction 32. Every time the unmanned helicopter 1 advances by the distance J, a group of laser spots 24 arranged on a straight line is formed, and the laser spots 24 can be expanded and distributed in the second direction 32 as a whole. That is, it is possible to scan an area having a width in the second direction 32.

By tilting the rotation axis 21 of the LiDAR sensor 20 with respect to the second direction 32 in this way, the irradiation position of the laser pulse 22 is set to the second direction 32 even when the LiDAR sensor 20 having a single scan line is used. It can be expanded and the irradiation leakage area can be reduced.

Next, measurement will be described when the rotation axis 21 of the LiDAR sensor 20 is oriented in a direction closer to the front-rear direction than the left-right direction of the aircraft of the unmanned helicopter 1.

FIG. 22 shows an unmanned helicopter 1 in a plan view seen from the vertical direction 33. In the example shown in FIG. 22, the rotating shaft 21 faces the front-rear direction of the body of the unmanned helicopter 1. In such a form, the signal processing circuit 15g (FIG. 4) of the unmanned helicopter 1 has the unmanned helicopter 1 so that the rotating shaft 21 faces the direction closer to the second direction 32 than the aircraft traveling direction (first direction 31). To fly. For example, as shown in FIG. 22, by flying the unmanned helicopter 1 diagonally forward to the right of the airframe, the unmanned helicopter 1 can be flown with the rotation axis 21 oriented in a direction close to the second direction 32. .. As a result, the measurement target area 50 can be measured with the rotation shaft 21 oriented in the direction close to the second direction 32.

Next, an unmanned helicopter 1 provided with a plurality of LiDAR sensors will be described.

FIG. 23 is a front view of the unmanned helicopter 1 provided with a plurality of LiDAR sensors. In the example shown in FIG. 23, the LiDAR sensor (second LiDAR sensor) 40 is provided in the unmanned helicopter 1 in addition to the LiDAR sensor 20. The LiDAR sensor 40 has the same configuration as the LiDAR sensor 20. The head of the LiDAR sensor 40 rotates about the rotation shaft 41. The head of the rotating LiDAR sensor 40 simultaneously emits N laser pulses 42 at a predetermined angle pitch α.

The number of LiDAR sensors provided in the unmanned helicopter 1 is arbitrary, and three or more LiDAR sensors may be provided in the unmanned helicopter 1. Here, an unmanned helicopter 1 provided with two LiDAR sensors will be illustrated and described.

FIG. 24 is a diagram illustrating a direction in which the rotation axes 21 and 41 of the LiDAR sensors 20 and 40 face. FIG. 24 shows the unmanned helicopter 1 in a plan view seen from the vertical direction 33. In a plan view, the rotation axis 41 of the LiDAR sensor 40 faces in a different direction from the rotation axis 21 of the LiDAR sensor 20. That is, the rotation axis direction 21a and the rotation axis direction 41a, which is the direction in which the rotation axis 41 faces, are different from each other. The angle θa formed by the rotation axis direction 41a and the second direction 32 may be the same as the angle θ, but may be different from each other.

During the measurement of the measurement target area 50, the rotation axis 41 is directed in a direction closer to the second direction 32 than the aircraft traveling direction (first direction 31) in a plan view. For example, when the aircraft traveling direction 31 is the forward direction, the rotation axis 21 of the LiDAR sensor 20 faces diagonally from the front left to the diagonally rear right, and the rotation axis 41 of the second LiDAR sensor 40 faces diagonally forward to the left. No.

FIG. 25 is a diagram showing N laser pulses 22 simultaneously emitted from the LiDAR sensor 20 and N laser pulses 42 simultaneously emitted from the LiDAR sensor 40. Similar to FIG. 6, FIG. 25 shows N laser pulses 22 emitted along a plane direction perpendicular to the vertical direction 33 among the laser pulses 22 emitted at predetermined angular pitch α. .. Further, FIG. 25 shows N laser pulses 42 emitted along the plane direction perpendicular to the vertical direction 33 among the laser pulses 42 emitted at each predetermined angular pitch α.

FIG. 26 is a diagram showing laser pulses 22 and 42 emitted from the traveling unmanned helicopter 1. For convenience of description, FIG. 26 shows the laser pulses 22 and 42 emitted along the plane direction perpendicular to the vertical direction 33 among the laser pulses 22 and 42 emitted at each predetermined angular pitch α. While the unmanned helicopter 1 travels a distance J, each of the LiDAR sensors 20 and 40 makes one rotation and emits N laser pulses 22 and 42 at a predetermined angle pitch α.

FIG. 7 described above shows a laser pulse 22 emitted from one LiDAR sensor 20. In the example shown in FIG. 7, a large number of laser pulses 22 can be irradiated to the area on the right side along the traveling direction 31 of the aircraft, but the number of laser pulse 22 irradiations is smaller in the area on the left side than in the area on the right side.

On the other hand, in the form in which the unmanned helicopter 1 is further equipped with the LiDAR sensor 40, as shown in FIG. 26, the area on the left side along the aircraft traveling direction 31 can be irradiated with a large number of laser pulses 22 from the LiDAR sensor 40. There is. By emitting the laser pulses 22 and 42 from the two LiDAR sensors 20 and 40 whose rotation axes are oriented in different directions, it is possible to irradiate a larger range of the laser pulses 22 and 42.

Further, since the two LiDAR sensors 20 and 40 emit laser pulses 22 and 42 in different directions, the area where it is difficult to irradiate many laser pulses from one LiDAR sensor is complemented by the other LiDAR sensor. be able to. As a result, more laser pulses 22 can be irradiated to the area along the traveling direction 31 of the aircraft.

Next, a modified example of the unmanned helicopter 1 provided with the two LiDAR sensors 20 and 40 will be described.

FIG. 27 is a diagram illustrating a direction in which the rotation axes 21 and 41 of the LiDAR sensors 20 and 40 face. In the example shown in FIG. 27, in a plan view, the rotation axis 41 of the LiDAR sensor 40 faces a direction closer to the first direction 31 than the second direction 32. The angle θb formed by the rotation axis direction 41a and the first direction 31 may be the same as the angle θ, or may be different from each other. During the measurement of the measurement target area 50, the rotation axis 41 of the LiDAR sensor 40 faces in a direction close to the aircraft traveling direction (first direction 31), so that the laser pulse 22 covers a wide range in the lateral direction with respect to the aircraft traveling direction 31. Can be irradiated. This makes it possible to measure a wider area during flight along a single path segment.

According to the above-described embodiment, the unmanned helicopter 1 can fly at an altitude lower than that of a conventional aircraft, thereby increasing the in-plane number density of laser spots and reducing the laser spot center spacing.

When the flight speed is reduced due to flight at a low altitude, the measurement target area becomes narrow because the cruising range is short in the multicopter that operates the electric motor with the electric power supplied from the battery. On the other hand, an unmanned helicopter that flies using an internal combustion engine as a power source has a long cruising range, so that a sufficient measurement target area can be secured even if the flight speed is reduced.

In this specification, an unmanned aerial vehicle provided with a LiDAR sensor has been illustrated and described. Although the mechanical rotation type, MEMS type, and phased array type LiDAR sensors have been exemplified, a flash LiDAR sensor may be used. Although the flash LiDAR sensor does not have a rotation axis or a swing axis, it may be attached to the unmanned helicopter 1 at a position and an angle capable of performing forest measurement for a forest spreading on a slope.

The exemplary embodiments of the present invention have been described above.

The measurement system 100 according to an embodiment of the present invention flies an unmanned helicopter 1 provided with a LiDAR sensor 20 to measure an area 50 to be measured. The measurement system 100 includes an unmanned helicopter 1, a LiDAR sensor 20 provided in the unmanned helicopter 1, and a control device 15 for controlling the flight of the unmanned helicopter 1. In the plan view seen from the vertical direction 33, when the aircraft traveling direction 31 of the unmanned helicopter 1 is the first direction 31 and the direction perpendicular to the first direction 31 is the second direction 32, the measurement target using the LiDAR sensor 20 is used. During the measurement of the area 50, the unmanned helicopter 1 flies in a state where the rotation axis 21 of the LiDAR sensor 20 faces a direction closer to the second direction 32 than the first direction 31.

During the measurement of the measurement target area 50 using the LiDAR sensor 20, the unmanned helicopter 1 flies in a state where the rotation axis 21 of the LiDAR sensor 20 faces a direction closer to the second direction 32 than the first direction 31. Since the LiDAR sensor 20 is rotating, the laser pulse 22 can be densely applied to the area along the aircraft traveling direction 31 in the process of the unmanned helicopter 1 traveling. Thereby, for example, in the form in which a plurality of laser pulses 22 are simultaneously emitted from the LiDAR sensor 20, the laser pulses 22 can be densely irradiated to the same location in the area along the aircraft traveling direction 31 from various angles. As a result, detailed three-dimensional point cloud data of the area along the aircraft traveling direction 31 can be acquired. Further, by rotating the LiDAR sensor 20, for example, the trees 56 constituting the forest 54 can be irradiated with the laser pulse 22 from various angles.

In the flight of one path segment included in the flight path 60, the area along the aircraft traveling direction 31 can be repeatedly irradiated with the laser pulse 22. This makes it possible to acquire high-density 3D point cloud data in the flight of that one path segment.

It is possible to acquire high-density 3D point cloud data of the area scanned by the LiDAR sensor 20 in the flight of one route segment without having to scan the area in detail again in the flight of another route segment.

The laser pulse 22 can be continuously applied to the same object in the measurement target area 50. Thereby, for example, when measuring while flying over the tree 56, between the point cloud data obtained by measuring while approaching the tree 56 and the point cloud data obtained by measuring while moving away from the tree 56. , The misalignment on the geographic coordinate system can be reduced.

In certain embodiments, the LiDAR sensor 20 may have its rotating shaft 21 oriented in a direction closer to the left-right direction than the front-rear direction of the unmanned helicopter 1.

In the normal flight posture of the unmanned helicopter 1 in which the front-rear direction of the aircraft faces the aircraft traveling direction 31, the rotation axis 21 of the LiDAR sensor 20 can be oriented closer to the second direction 32 than the first direction 31.

In one embodiment, during measurement of the measurement target area 50 using the LiDAR sensor 20, the control device 15 directs the rotation axis 21 of the LiDAR sensor 20 to face a direction closer to the second direction 32 than the first direction 31. The unmanned helicopter 1 may be flown.

Even if the rotation axis 21 of the LiDAR sensor 20 is not oriented closer to the left-right direction than the front-rear direction of the unmanned helicopter 1, the unmanned helicopter is oriented with the rotation axis 21 oriented toward the second direction 32. 1 can be flown.

In one embodiment, the rotation axis 21 of the LiDAR sensor 20 may face the second direction 32 during the measurement of the measurement target area 50.

In the process of traveling the unmanned helicopter 1, the laser pulse 22 can be more closely irradiated to the area along the aircraft traveling direction 31. As a result, more detailed three-dimensional point cloud data of the area along the aircraft traveling direction 31 can be acquired. Further, by rotating the LiDAR sensor 20, for example, the trees 56 constituting the forest 54 can be irradiated with the laser pulse 22 from various angles.

In one embodiment, the rotation axis 21 of the LiDAR sensor 20 may be tilted with respect to the second direction 32 in a plan view during the measurement of the measurement target area 50.

The irradiation position of the laser pulse 22 formed on the ground by the LiDAR sensor 20 can be expanded and distributed in the second direction 32. When the LiDAR sensor 20 having one scan line is used, if the rotation axis 21 coincides with the second direction 32, the irradiation position is located on a straight line parallel to the first direction 31. By expanding the irradiation position of the laser pulse 22 in the second direction 32, the irradiation leakage region can be reduced.

In certain embodiments, the LiDAR sensor 20 may emit a laser pulse 22 in a direction having a predetermined angle with respect to the rotation axis 21 and rotate the direction in which the laser pulse 22 is emitted around the rotation axis 21.

When a LiDAR sensor 20 having one scan line is used, the irradiation positions of the laser pulses 22 formed on the ground are lined up on one line, but an area having a width in the second direction 32 can be scanned.

In one embodiment, the measurement target area 50 may include a forest 54 in which a plurality of trees 56 rise from the ground surface 59.

The forest 54 can be irradiated with the laser pulse 22 from various angles, and the laser pulse 22 reaches not only the canopy 56a of the tree 56 but also the trunk 56b of the tree 56, the understory vegetation 58, the ground surface 59, etc., and is reflected. Will be done. As a result, it is possible to obtain three-dimensional point cloud data including not only the canopy point cloud but also the trunk point cloud, the understory vegetation point cloud and the ground surface point cloud.

In certain embodiments, the ground surface 59 includes a slope 52, and during measurement of the area 50 to be measured, the control device 15 may raise or lower the unmanned helicopter 1 along the slope 52.

The forest 54 spreading on the slope 52 can be irradiated with the laser pulse 22 not only from the diagonally upward direction but also from the lateral direction, or the laser pulse 22 can be irradiated from the diagonally downward direction. The laser pulse 22 reaches not only the canopy 56a of the tree 56 but also the trunk 56b of the tree 56, the understory vegetation 58, the ground surface 59, and the like, and is reflected. As a result, it is possible to obtain three-dimensional point cloud data including not only the canopy point cloud but also the trunk point cloud, the understory vegetation point cloud and the ground surface point cloud.

In certain embodiments, during the measurement of the area 50 to be measured, the control device 15 may fly the unmanned helicopter 1 along the first path segment 60a across the plurality of contour lines 62.

By flying the unmanned helicopter 1 along the slope 52 so as to cross the plurality of contour lines 62, the laser pulse 22 can be applied to the forest 54 spreading on the slope 52 not only from diagonally upward but also from the lateral direction. , The laser pulse 22 can be irradiated from diagonally downward.

In one embodiment, during the measurement of the measurement target area 50, the control device 15 may fly the unmanned helicopter 1 with the rotation axis 21 of the LiDAR sensor 20 facing in the direction along the contour line 62.

Since the unmanned helicopter 1 flies along the slope 52 with the rotation axis 21 of the LiDAR sensor 20 facing the direction along the contour line 62, the unmanned helicopter 1 flies not only from diagonally upward to the forest 54 spreading on the slope 52. , The laser pulse 22 can be irradiated from the lateral direction, or the laser pulse 22 can be irradiated from the diagonally downward direction.

In certain embodiments, the flight path 60 to which the unmanned helicopter 1 flies when measuring the measurement target area 50 may include a second path segment 60b that intersects the first path segment 60a in plan view.

By flying a plurality of path segments that intersect each other, the measurement target area 50 can be irradiated with the laser pulse 22 from a plurality of directions, and detailed three-dimensional point cloud data of the measurement target area 50 can be acquired. ..

In one embodiment, the flight path 60 for flying the unmanned helicopter 1 when measuring the measurement target area 50 may include a grid-like flight path 60.

By flying along the grid-shaped flight path 60, the measurement target area 50 can be irradiated with the laser pulses 22 from a plurality of directions, and detailed three-dimensional point cloud data of the measurement target area 50 can be acquired.

In one embodiment, the second LiDAR sensor 40 is provided in the unmanned helicopter 1 in addition to the LiDAR sensor 20, and the rotation axis 41 of the second LiDAR sensor 40 is in a direction different from the rotation axis 21 of the LiDAR sensor 20 in a plan view. You may be facing.

By emitting the laser pulses 22 and 42 from the two LiDAR sensors 20 and 40 whose rotating shafts 21 and 41 are oriented in different directions, it is possible to irradiate a larger range of the laser pulses 22 and 42.

In a certain embodiment, during the measurement of the measurement target area 50, the rotation axis 41 of the second LiDAR sensor 40 faces a direction closer to the second direction 32 than the first direction 31 in a plan view, and the aircraft traveling direction 31 is set. When viewed in the forward direction, the rotation axis 21 of the LiDAR sensor 20 may face diagonally from the front left to the diagonally rear right, and the rotation axis 41 of the second LiDAR sensor 40 may face diagonally forward to the left and diagonally rearward to the left.

More laser pulses 22 can be applied to the area along the aircraft traveling direction 31. Further, by emitting laser pulses 22 in different directions from the two LiDAR sensors 20, the area where it is difficult to irradiate many laser pulses 22 from one LiDAR sensor 20 is complemented by the other LiDAR sensor 20. Can be done.

In a certain embodiment, during the measurement of the measurement target area 50, the rotation axis 41 of the second LiDAR sensor 40 may face in a direction closer to the first direction 31 than the second direction 32 in a plan view.

The laser pulse 22 can be irradiated over a wide range in the lateral direction with respect to the traveling direction 31 of the aircraft.

In certain embodiments, the unmanned helicopter 1 may be an unmanned helicopter or an unmanned multicopter powered by an internal combustion engine.

When an electric motor operated by electric power supplied from a battery is used as a power source, the cruising range is short, so that the measurement target area 50 becomes narrow. On the other hand, when the internal combustion engine is used as the power source, the cruising range is long, so that a sufficient measurement target area 50 can be secured.

In the method for measuring the measurement target area 50 according to the embodiment of the present invention, the unmanned helicopter 1 provided with the LiDAR sensor 20 is flown to measure the measurement target area 50. The method of measuring the measurement target area 50 is to set the flight path 60 of the unmanned helicopter 1, to fly the unmanned helicopter 1 along the set flight path 60, and to measure the plane view from the vertical direction 33. When the traveling direction of the unmanned helicopter 1 is the first direction 31 and the direction perpendicular to the first direction 31 is the second direction 32, the rotation axis 21 of the LiDAR sensor 20 is in the second direction 32 rather than the first direction 31. The LiDAR sensor 20 scans the measurement target area 50 in a state of facing a close direction.

During the measurement of the measurement target area 50 using the LiDAR sensor 20, the unmanned helicopter 1 flies in a state where the rotation axis 21 of the LiDAR sensor 20 faces a direction closer to the second direction 32 than the first direction 31. Since the LiDAR sensor 20 is rotating, the laser pulse 22 can be densely applied to the area along the aircraft traveling direction 31 in the process of the unmanned helicopter 1 traveling. Thereby, for example, in the form in which a plurality of laser pulses 22 are simultaneously emitted from the LiDAR sensor 20, the laser pulses 22 can be densely irradiated to the same location in the area along the aircraft traveling direction 31 from various angles. As a result, detailed three-dimensional point cloud data of the area along the aircraft traveling direction 31 can be acquired. Further, by rotating the LiDAR sensor 20, for example, the trees 56 constituting the forest 54 can be irradiated with the laser pulse 22 from various angles.

In the flight of one path segment included in the flight path 60, the area along the aircraft traveling direction 31 can be repeatedly irradiated with the laser pulse 22. This makes it possible to acquire high-density 3D point cloud data in the flight of that one path segment.

It is possible to acquire high-density 3D point cloud data of the area scanned by the LiDAR sensor 20 in the flight of one route segment without having to scan the area in detail again in the flight of another route segment.

The laser pulse 22 can be continuously applied to the same object in the measurement target area 50. Thereby, for example, when measuring while flying over the tree 56, between the point cloud data obtained by measuring while approaching the tree 56 and the point cloud data obtained by measuring while moving away from the tree 56. , The misalignment on the geographic coordinate system can be reduced.

In one embodiment, the flight path 60 includes a plurality of path segments, and the above method combines the sensor data output from the LiDAR sensor 20 during flight for each of the plurality of path segments to generate three-dimensional point cloud data. May be further executed.

It is possible to acquire high-density 3D point cloud data of the area scanned by the LiDAR sensor 20 in the flight of one route segment without having to scan the area in detail again in the flight of another route segment. As a result, high-density three-dimensional point cloud data of the measurement target area 50 can be acquired.

In one embodiment, the area 50 to be measured includes the forest 54 on the slope 52, and the step of setting the flight path 60 of the unmanned helicopter 1 refers to the contour line 62 data in the target area and is a route segment that crosses the plurality of contour lines 62. May include setting a flight path 60 including.

By flying the unmanned helicopter 1 along the slope 52 so as to cross the plurality of contour lines 62, the laser pulse 22 can be applied to the forest 54 spreading on the slope 52 not only from diagonally upward but also from the lateral direction. , The laser pulse 22 can be irradiated from diagonally downward. The laser pulse 22 reaches not only the canopy 56a of the tree 56 but also the trunk 56b of the tree 56, the understory vegetation 58, the ground surface 59, and the like, and is reflected. As a result, it is possible to obtain three-dimensional point cloud data including not only the canopy point cloud but also the trunk point cloud, the understory vegetation point cloud and the ground surface point cloud.

The technique of the present invention can be suitably used in a technical field in which an unmanned aerial vehicle is used to measure a measurement target area.

1: Unmanned helicopter (unmanned aircraft), 2: Main body, 3: Tail body, 4: Aircraft, 5: Main rotor, 6: Tail rotor, 7: Radiator, 8: Engine, 9: Power generator, 10: Control panel , 11: Indicator light, 12: Skid, 13: Remote control receiving antenna, 15: Flight control box (control device), 15a: GPS module, 15b: Acceleration sensor, 15c: Pressure sensor, 15d: Geomagnetic sensor, 15e: Ultrasonic Sensor, 15f: Communication circuit, 15g: Signal processing circuit, 15h: ROM, 15i: RAM, 15j: Storage device, 15k: Internal bus, 20: LiDAR sensor, 21: Rotation axis, 21a: Rotation axis direction, 22: Laser Pulse, 23: Head 24: Laser spot, 25: Bracket, 31: Aircraft traveling direction (first direction), 32: Direction perpendicular to the aircraft traveling direction (second direction), 33: Vertical direction, 40: LiDAR sensor ( 2nd LiDAR sensor), 41: rotation axis, 41a: rotation axis direction, 42: laser pulse, 50: measurement target area, 52: slope, 54: forest, 56, 57: tree, 56a: canopy, 56b: trunk, 58 : Lower vegetation 59: Ground surface 60: Flight path, 60a: First path segment, 60b: Second path segment, 62: Contour line 66: Flight path, 66a, 66b: Path segment, 70: Tablet computer, 71: CPU, 72: Memory, 73: Communication circuit, 74: Image processing circuit, 75: Display, 76: Touch screen panel, 77: Communication bus, 80: Base station control device, 90: Map data, 100: Measurement system

Claims (19)

It is a measurement system that measures the measurement target area by flying an unmanned aerial vehicle equipped with a lidar sensor.
With unmanned aerial vehicles,
The rider sensor provided on the unmanned aerial vehicle and
The control device that controls the flight of the unmanned aerial vehicle and
Equipped with
When the aircraft traveling direction of the unmanned aerial vehicle is the first direction and the direction perpendicular to the first direction is the second direction in a plan view seen from the vertical direction.
A measurement system in which the unmanned aerial vehicle flies in a state where the rotation axis of the rider sensor faces a direction closer to the second direction than the first direction during measurement of the measurement target area using the rider sensor. The measurement system according to claim 1, wherein the rider sensor has its rotation axis oriented in a direction closer to the left-right direction than the front-rear direction of the body of the unmanned aerial vehicle. During the measurement of the measurement target area using the rider sensor, the control device flies the unmanned aerial vehicle so that the rotation axis of the rider sensor faces a direction closer to the second direction than the first direction. The measurement system according to claim 1 or 2. The measurement system according to any one of claims 1 to 3, wherein the rotation axis of the rider sensor faces the second direction during measurement of the measurement target area. The measurement system according to any one of claims 1 to 3, wherein the rotation axis of the rider sensor is tilted with respect to the second direction in the plan view during the measurement of the measurement target area. The measurement system according to claim 5, wherein the lidar sensor emits a laser pulse in a direction having a predetermined angle with respect to the rotation axis, and rotates the direction in which the laser pulse is emitted around the rotation axis. The measurement system according to any one of claims 1 to 6, wherein the measurement target area includes a forest in which a plurality of trees rise from the ground surface. The ground surface includes a slope and
The measurement system according to claim 7, wherein the control device raises or lowers the unmanned aerial vehicle along the slope during measurement of the measurement target area. The measurement system according to claim 8, wherein during measurement of the measurement target area, the control device flies the unmanned aerial vehicle along a first path segment that crosses a plurality of contour lines. The measurement system according to claim 8 or 9, wherein during the measurement of the measurement target area, the control device flies the unmanned aerial vehicle with the rotation axis of the rider sensor oriented in a direction along a contour line. The measurement system according to claim 9, wherein the flight path for flying the unmanned aerial vehicle when measuring the measurement target area includes a second path segment that intersects with the first path segment in the plan view. The measurement system according to any one of claims 1 to 11, wherein the flight path for flying the unmanned aerial vehicle when measuring the measurement target area includes a grid-like flight path. In addition to the rider sensor, a second rider sensor is provided on the unmanned aerial vehicle.
The measurement system according to any one of claims 1 to 12, wherein the rotation axis of the second rider sensor faces a direction different from the rotation axis of the rider sensor in the plan view. During the measurement of the measurement target area, in the plan view,
The rotation axis of the second rider sensor is oriented in a direction closer to the second direction than the first direction.
When the traveling direction of the aircraft is the forward direction, the rotation axis of the rider sensor faces diagonally left front to diagonally rear right, and the rotation axis of the second rider sensor faces diagonally forward left to diagonally rear left. The measurement system according to claim 13. The measurement system according to claim 13, wherein the rotation axis of the second rider sensor faces a direction closer to the first direction than the second direction in the plan view during the measurement of the measurement target area. .. The measurement system according to any one of claims 1 to 15, wherein the unmanned aerial vehicle is an unmanned helicopter or an unmanned multicopter powered by an internal combustion engine. It is a method of flying an unmanned aerial vehicle equipped with a lidar sensor to measure the measurement target area.
Setting the flight path of the unmanned aerial vehicle,
Flying the unmanned aerial vehicle along the set flight path,
In a plan view seen from the vertical direction, when the traveling direction of the unmanned aircraft is the first direction and the direction perpendicular to the first direction is the second direction, the rotation axis of the rider sensor is from the first direction. The lidar sensor scans the measurement target area while facing the direction close to the second direction.
How to do it. The flight path includes multiple path segments and includes
The method is
To generate 3D point cloud data by combining the sensor data output from the rider sensor during flight of each of the plurality of path segments.
17. The method of claim 17. The measurement target area includes the forest on the slope and
17. The method of claim 17 or 18, wherein the step of setting the flight path of the unmanned aerial vehicle refers to the contour data in the target area and includes setting a flight path including a route segment that crosses a plurality of contour lines. ..

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