WO2021020569A1

WO2021020569A1 - Method for performing forest mensuration, forest mensuration system, method for determining flight path of unmanned aerial vehicle, image capturing method, dispersion method, and computer program

Info

Publication number: WO2021020569A1
Application number: PCT/JP2020/029506
Authority: WO
Inventors: 準矢嶋
Original assignee: ヤマハ発動機株式会社
Priority date: 2019-07-31
Filing date: 2020-07-31
Publication date: 2021-02-04
Also published as: JP7141538B2; JPWO2021020569A1

Abstract

According to the present invention, an unmanned aerial vehicle equipped with a LiDAR sensor is flown to perform forest mensuration of a forest on an inclined surface. The LiDAR sensor is mounted on the unmanned aerial vehicle in such a way that the axis of rotation or the axis of oscillation thereof faces in the direction of travel of the aircraft. The method for performing forest mensuration includes (i) scanning the forest using the LiDAR sensor while flying the unmanned aerial vehicle at a predetermined absolute altitude along a first contour line, and (ii) re-scanning the forest using the LiDAR sensor while flying the unmanned aerial vehicle at the predetermined absolute altitude along a second contour line different from the first contour line.

Description

How to make forest measurements, forest measurement systems, how to determine the flight path of unmanned aerial vehicles, how to shoot, how to spray and computer programs

The present invention relates to a technique for performing forest measurement using an unmanned aerial vehicle, a technique for determining a flight path of an unmanned aerial vehicle, and the like.

Various methods are known as methods for performing forest measurement. 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 transmits radar waves having different wavelengths from the sky to the forest, and calculates 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. 2016-070708

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 takes a lot of time and effort to acquire two types of point cloud data.

It is required to measure the canopy and trunk of trees in the forest using an unmanned aerial vehicle.

A method according to an embodiment of the present invention is a method of flying an unmanned aerial vehicle equipped with a lidar (LiDAR) sensor to perform forest measurement for a forest on a slope, and the rotation axis or swing of the rider sensor. The axis is mounted on the unmanned aerial vehicle so as to face the direction of travel of the aircraft, and (i) the rider sensor scans the forest while flying the unmanned aerial vehicle at a predetermined absolute altitude along the first contour line. , And (ii) the rider sensor rescans the forest while flying the unmanned aerial vehicle along a second contour line different from the first contour line at the predetermined absolute altitude.

In certain embodiments, the method may further include pre-designating the first contour lines, the second contour lines and the predetermined absolute altitude prior to the steps (i) and (ii).

In certain embodiments, the method further comprises causing the rider sensor to scan the edge of the forest while flying the unmanned aerial vehicle over a position a predetermined distance away from the edge. It may be included.

In certain embodiments, the rider sensor may scan the canopy and trunk of each tree in the forest.

In certain embodiments, the steps (i) and (ii) may include causing the rider sensor to scan the forest with a laser pulse emitted in the horizontal direction.

In certain embodiments, steps (i) and (ii) may include causing the rider sensor to scan the forest using laser pulses emitted in an oblique direction.

In certain embodiments, the unmanned aerial vehicle may be an unmanned helicopter or an unmanned multicopter.

A method according to an embodiment of the present invention is a method of determining a flight path of an unmanned aerial vehicle equipped with an observer, in which the observation target area by the observer is specified, and when the observation target area includes a slope. With reference to the contour data in the observation target area, determining a plurality of route segments in which the unmanned aerial vehicle flies at a predetermined absolute altitude along any of the contour lines, and determining a flight path including the plurality of route segments. To decide, to do.

In certain embodiments, determining the plurality of route segments may include setting a plurality of transit points on one or more selected contour lines and specifying the absolute altitude. ..

In certain embodiments, the observation area may include forests on the slope.

In certain embodiments, the observer may be a lidar (LiDAR) sensor.

In certain embodiments, determining the flight path may include determining the flight path at the edge of the forest that passes over a position a predetermined distance away from the edge.

In certain embodiments, the observer may be an infrared camera.

A method according to an embodiment of the present invention is a method of flying an unmanned aerial vehicle equipped with a lidar (LiDAR) sensor to perform forest measurement for a forest on a slope, and the rotation axis or swing of the rider sensor. The axis is mounted on the unmanned aerial vehicle so as to face the direction of travel of the aircraft, and (i) the rider sensor scans the forest while flying the unmanned aerial vehicle at a predetermined absolute altitude and a predetermined first true altitude. And (ii) scan the forest again with the rider sensor while flying the unmanned aerial vehicle at the predetermined absolute altitude and a predetermined second true altitude different from the predetermined first true altitude. Do what you want.

The forest measurement system according to an embodiment of the present invention is a forest measurement system having an unmanned aircraft and a computer device, and for flying the unmanned aircraft to perform forest measurement targeting a forest on a slope. The unmanned aircraft has a lidar (LiDAR) sensor, a first signal processing circuit, a first storage device, and a first communication circuit, and the rotation axis or swing axis of the rider sensor determines the traveling direction of the aircraft. It is mounted on the unmanned aircraft so as to face the unmanned aircraft, and the computer device includes a display device, an input device, a second signal processing circuit, a second storage device that stores information about contour lines, and a second communication circuit. Then, the second signal processing circuit acquires information about the contour line from the second storage device, receives designation of the first contour line, the second contour line, and the absolute altitude via the input device, and receives the designation of the designated first contour line. The first contour line, the second contour line, and the absolute altitude data are transmitted to the unmanned aircraft via the second communication circuit, and the first signal processing circuit is the first through the first communication circuit. The data of the contour line, the second contour line and the absolute altitude are received, the received data of the first contour line, the second contour line and the absolute altitude are stored in the first storage device, and the unmanned aircraft is stored in the first storage device. The rider sensor scans the forest while flying along the contour line at the absolute altitude, and the rider sensor scans the forest again while flying the unmanned aircraft at the absolute altitude along the second contour line. Let me.

The imaging method according to an embodiment of the present invention is a method of photographing an observation target by using an unmanned aerial vehicle equipped with an imaging device, and the observation target area is specified, and when the observation target area includes a slope, the above-mentioned With reference to the contour data in the observation target area, determine a plurality of route segments in which the unmanned aerial vehicle flies at a predetermined absolute altitude along any of the contour lines, and determine a flight route including the plurality of route segments. That is, taking a picture with the image pickup device while flying the unmanned aerial vehicle along the determined flight path.

The spraying method according to an embodiment of the present invention is a method of spraying a drug using an unmanned aerial vehicle equipped with a drug spraying device, specifying an area to be sprayed by the spraying device, and the spraying target area is a slope. In the case of including, the plurality of route segments in which the unmanned aerial vehicle flies at a predetermined absolute altitude along any of the contour lines are determined by referring to the contour data in the spraying target area. Determining the flight path and spraying the drug while flying the unmanned aerial vehicle along the determined flight path.

A computer program according to an embodiment of the present invention is a computer program for causing a computer to control forest measurement for a forest on a slope by flying an unmanned aircraft equipped with a lidar (LiDAR) sensor. The axis of rotation or swing of the rider sensor is mounted on the unmanned aircraft so that it faces the direction of travel of the aircraft, and the computer program (i) flies the unmanned aircraft along a first contour line at a predetermined absolute altitude. While allowing the rider sensor to scan the forest, and (ii) flying the unmanned aircraft along a second contour line different from the first contour line at the predetermined absolute altitude, the rider sensor said. Let the computer perform control of rescanning the forest.

A method according to an embodiment of the present invention is a method of flying an unmanned aerial vehicle equipped with a lidar (LiDAR) sensor to perform forest measurement for a forest, wherein the rotation axis or the swing axis of the lidar sensor is , It is mounted on the unmanned aerial vehicle so as to face the traveling direction of the aircraft, and the lidar sensor is used to emit the laser pulse while changing the emission direction at a predetermined angular pitch to measure the surrounding space. The distance is L, the flight speed of the unmanned aerial vehicle is V, the number of laser pulses emitted simultaneously in the same angular direction is N, the frequency of the laser pulses emitted in the same angular direction is f, and the predetermined angular pitch is When α is set, forest measurement targeting the forest using the lidar sensor while flying the unmanned aerial vehicle so that the relative value of α / L with respect to V / (f · N) falls within a predetermined range. Do what you do.

In a certain embodiment, the predetermined angle pitch α may be a fixed value.

In a certain embodiment, the predetermined angle pitch α may be fixed to a settable minimum value.

In a certain embodiment, the lidar sensor is of a mechanical rotation type, and when the number of times the laser pulse is emitted per unit time at one outlet that emits the laser pulse is M and the number of rotations per unit time is R, The predetermined angle pitch α is obtained by α (rad) = 2.π · R / M, and the forest measurement is performed by (2 · π · R / M) · L with respect to V / (f · N). It may include flying the unmanned aerial vehicle so that the relative value falls within the predetermined range.

In a certain embodiment, the number of times of emission M per unit time and the number of rotations R per unit time may be variable values.

In a certain embodiment, the number of emission times M per unit time and the number of rotations R per unit time may be fixed values.

In one embodiment, the rider sensor is of a mechanical rotation type, the predetermined angle pitch α is smaller than the divergence angle θ _{1 of the} laser pulse in the direction perpendicular to the rotation axis, and the method is such that the rider sensor The flight speed of the unmanned aircraft so that the flight distance J that the unmanned aircraft flies during one rotation is shorter than the length K in the direction parallel to the traveling direction of the aircraft at the laser spot formed in the forest. It may include adjusting V, the number of revolutions R of the rider sensor per unit time, and at least one of the altitude H of the unmanned aircraft.

In certain embodiments, the method changes the divergence angle θ by changing at least one of the number of times M and the number of revolutions R of the pulse emitted per unit time at one outlet for emitting the laser pulse. It may include adjusting the predetermined angle pitch α so as to be smaller than ₁ .

In certain embodiments, the forest may be a sloped forest.

The forest measurement system according to an embodiment of the present invention is a forest measurement system having an unmanned aircraft and a computer device for flying the unmanned aircraft to perform forest measurement targeting the forest, and is the unmanned forest measurement system. The aircraft has a lidar (LiDAR) sensor, a first signal processing circuit, a storage device, and a first communication circuit, and the rotation axis or swing axis of the lidar (LiDAR) sensor faces the traveling direction of the aircraft. The computer device includes a display device, an input device, a second signal processing circuit, and a second communication circuit, and the second signal processing circuit is the input device. The number N of laser pulses emitted simultaneously in the same angular direction, the frequency f of the laser pulses emitted in the same angular direction, and the predetermined number N of the predetermined angle pitch α are specified. The data of the frequency f and the predetermined angle pitch α are transmitted to the unmanned aircraft via the second communication circuit, and the first signal processing circuit is the number N, the said, via the first communication circuit. The data of the frequency f and the predetermined angle pitch α are received, the received data of the number N, the frequency f and the predetermined angle pitch α are stored in the storage device, the distance to the forest is L, and the unmanned aircraft. When the flight speed of is V, the unmanned aircraft is flown so that the relative value of α · L with respect to V / (f · N) falls within a predetermined range, and the forest is cleared by using the rider sensor. Perform target forest measurement.

A computer program according to an embodiment of the present invention is a computer program for causing a computer to control forest measurement for a forest by flying an unmanned aircraft equipped with a lidar (LiDAR) sensor. The rotation axis or swing axis of the aircraft is mounted on the unmanned aircraft so as to face the traveling direction of the aircraft, and the computer program uses the lidar sensor to emit while changing the emission direction of the laser pulse at a predetermined angular pitch. The surrounding space is measured, the distance to the forest is L, the flight speed of the unmanned aircraft is V, the number of laser pulses emitted simultaneously in the same angular direction is N, and the laser pulses are emitted in the same angular direction. When the frequency of the laser pulse is f and the predetermined angular pitch is α, the unmanned aircraft is being flown so that the relative values of α and L with respect to V / (f ・ N) are within a predetermined range. The computer is made to control the forest measurement for the forest by using the lidar sensor.

In the embodiment of the present invention, when an unmanned aerial vehicle equipped with a lidar (LiDAR) sensor is flown to perform forest measurement for a forest, the bias of the spatial density of the acquired point cloud data is suppressed, and the point cloud data It makes it possible to accurately determine or estimate the position and shape of the canopy and trunk from.

It is a figure which shows the unmanned helicopter 1 which performs the forest measurement. It is an external side view of the unmanned helicopter 1 equipped with the LiDAR sensor 20. It is a front view of the unmanned helicopter 1. It is a figure which shows the hardware configuration example of the flight control box 15. It is a figure which shows the unmanned helicopter 1 which performs the forest measurement for the forest 54 of the slope 52 using the LiDAR sensor 20. It is a figure which shows the modification about the mounting position of the LiDAR sensor 20. It is a perspective view which shows a part of the flight path 60 in an exemplary embodiment. It is a top view which shows a part of the flight path 60. FIG. 5 is a cross-sectional view of a slope 52 showing an unmanned helicopter 1 flying along the first contour line 60a and an unmanned helicopter 1 flying along the second contour line 60b. It is a figure which shows the distribution of the laser pulse incident on the slope 52 when the absolute altitude AGL is made constant. It is a figure which shows the distribution of the laser pulse incident on the slope 52 when the true altitude MSL is maintained constant. It is a figure which shows the result of the forest measurement performed by the method which concerns on an exemplary embodiment. It is a figure which shows an example of the forest measurement system 100 including an unmanned helicopter 1 and a tablet computer 70. It is a figure which shows an example of the forest measurement system 100 including an unmanned helicopter 1 and a base station control device 80. It is a figure which shows the hardware configuration example of a tablet computer 70. It is a figure which shows an example of the contour line data 90 in the observation target area read into the memory 72. It is a flowchart which shows the procedure of the flight path setting processing by an exemplary embodiment. It is a flowchart which shows the procedure of the flight operation of the unmanned helicopter 1 which set the flight path. It is a figure which shows the detail of the process of step S14 in FIG. It is a figure which shows the slope 52 of the mountain 50 scanned by the unmanned helicopter 1 in flight. It is a figure for demonstrating the relationship of two sides constituting the region S in FIG. It is a flowchart which shows the procedure of the process for making the measurement point density uniform by changing a parameter. It is a flowchart which shows the specific example of the process shown in FIG. It is a figure which shows typically the plurality of laser pulses 22 emitted from the LiDAR sensor 20 when the unmanned helicopter 1 in flight is seen from the front. It is a figure which shows typically the plurality of laser pulses 22 emitted from the LiDAR sensor 20 when the unmanned helicopter 1 in flight is viewed from the side. It is a figure which shows the laser spot formed on the measurement object 51 by the laser pulse 22. It is a flowchart which shows the procedure of the forest measurement which performs while irradiating the forest 54 which is an example of a measurement object 51 evenly with a laser pulse 22.

In order to manage and use forest resources, it is important to perform 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, a laser ranging device (LiDAR sensor) is mounted on an unmanned aerial vehicle, and forest measurement is being carried out from the air using the LiDAR sensor.

When using an unmanned aerial vehicle to measure deep forests in the mountains, especially forests on slopes, it is necessary to fly the unmanned aerial vehicle so that it does not come into contact with the vegetation on the slopes and slopes of the mountains during flight. ..

As a flight method for aircraft, etc., it is conceivable to fly while following the terrain (that is, keeping the absolute altitude constant), or to fly while maintaining a sufficient altitude above sea level.

The former has the advantage that the density of measurement points by the LiDAR sensor can be made uniform when the measurement target is directly below, but the distance from the slope can fluctuate greatly. There is a new problem that the measurement point density of the pulse of the laser beam incident on the slope is not uniform and is biased. There is room for improvement as a forest measurement for slope forests.

In the latter case, the flight altitude (elevation above sea level) is generally determined based on the altitude point of the highest mountain in the target area of observation (measurement, surveying, search). Since it flies at a relatively high position, the density of measurement points by the LiDAR sensor decreases even directly below. The density of measurement points for pulses incident on the slope is lower. There is a lot of room for improvement as a measurement method.

Before explaining the embodiments of the present disclosure, definitions of terms used in the present specification will be described.

<Terms>
In the present specification, "forest measurement" includes scanning a forest from the sky using a LiDAR sensor and acquiring scan data itself. 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 measurement" 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 / or 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 on which a person as a pilot does not board, and is sometimes called a drone. Aircraft may include rotorcraft and fixed-wing aircraft. An example of an unmanned aerial vehicle with rotors is an unmanned helicopter or 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 can be either autonomous flight by computer program, semi-autonomous flight by partially automating, or remote control flight by a person using radio. The unmanned aerial vehicle can fly while measuring and correcting the current position three-dimensionally with the help of GNSS (Global Navigation Satellite System). In the exemplary embodiments 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-pilots.

"Contour line" is a curve that connects points at the same height from the standard sea level in order to accurately represent the undulations of the land on the 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 standard sea level is called "elevation". On Japanese maps, depending on the scale, a main curve is drawn every 10 m above sea level, and a total curve is drawn every 50 m. 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.

Furthermore, in this specification, the "contour line" includes a virtual curve connecting positions at the same height as the standard sea level on the actual terrain. The "equal height above the standard sea level" here does not have to be exact. For example, a virtual curve connecting positions at heights within ± 30 meters of "equal height to standard sea level" can also be contour lines. Furthermore, when an unmanned aerial vehicle is flying and measures the altitude (contour line) of a predetermined position using a LiDAR sensor, a virtual position with a height within ± 50 meters is connected in consideration of measurement error. Curves may be included as contour lines.

"Absolute altitude" refers to the distance from the ground surface or water surface, and can also be expressed as "AGL" (Above Ground Level). When the aircraft is flying in the mountains, the vertical distance from the surface of the mountains to the aircraft is the "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 (lidar) sensor described later as an absolute altitude. Further, 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.

"True altitude" means the height from the average sea level (MSL; Mean Sea Level). In this specification, for convenience of explanation, "true altitude" and "elevation" are assumed to be equal. That is, the "average sea level" that defines "true altitude" is the average sea level of Tokyo Bay.

Hereinafter, embodiments of the forest measurement method according to the present invention will be described with reference to the attached drawings.

FIG. 1 shows an unmanned helicopter 1 that performs forest measurement. In an exemplary embodiment, forest measurement is performed on forest 54 on slope 52 of mountain 50. The area selected as the target for forest measurement, including the mountain 50 or the slope 52, may be referred to as an “observation target area”. The “observation target area” includes the ground surface of the forest 54 on the slope 52 and / or the mountain 50, and may further include the forest and the ground surface on a flat land.

The unmanned helicopter 1 is equipped with a lidar (LiDAR) sensor, which will be described later. FIG. 2 is an external side view of the unmanned helicopter 1 equipped with the 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 pulses”) 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 / or trunk of each tree constituting the forest 54, or the ground surface such as the slope 52 of the mountain 50 or flat land.

The LiDAR sensor 20 has a plurality of methods depending on the difference in the method of emitting a laser pulse. The plurality of methods are, for example, a mechanical rotation method, a MEMS method, and a phased array method. The mechanical rotation type LiDAR sensor has a tubular shape, and rotates a detector that detects a laser and reflected light of a laser pulse to scan 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 using a MEMS mirror, and scans a measurement object within a predetermined angle range centered on the swing axis. The phased array type LiDAR sensor controls the phase of light to swing the light emission direction, and scans a measurement object within a predetermined angle range centered on the swing axis.

In the present embodiment, the rotation axis or the swing axis of the LiDAR sensor is mounted so as to face the traveling direction of the unmanned helicopter 1. The forest measurement method according to the present embodiment is (i) to scan the forest 54 on the slope 52 with a LiDAR sensor while flying the unmanned helicopter 1 along the first contour line 60a at a predetermined absolute altitude, and (ii). This includes rescanning the forest 54 with a LiDAR sensor while flying the unmanned helicopter 1 along a second contour line 60b different from the first contour line 60a at the same absolute altitude. The absolute altitude can be appropriately determined according to the height of each tree constituting the forest 54. An example of absolute altitude is 50m. Since the unmanned helicopter 1 keeps the absolute altitude constant, it is possible to secure a sufficient distance between the unmanned helicopter 1 and the trees even in a mountainous area where there is a steep height difference.

Since the LiDAR sensor is mounted on the unmanned helicopter 1 so that its rotation axis or rocking axis faces the airframe traveling direction of the unmanned helicopter 1, the rotation axis or rocking axis generally coincides with the direction in which the contour lines extend. In particular, on the slope 52, the laser pulse can be irradiated substantially perpendicular to the trunks of the trees constituting the forest 54, that is, from the lateral direction of the trees. This makes it easier for the laser pulse to pass between the leaves that grow horizontally, basically because of the sunlight, so it is possible to measure not only the canopy of the trees but also the trunk.

In the above-mentioned forest measurement method, the significance of flying the unmanned helicopter 1 along the contour line is to keep the distance from the LiDAR sensor of the unmanned helicopter 1 to the slope 52 substantially constant. By keeping the distance substantially constant, the number density per unit area of the laser pulses emitted in the direction of the slope 52, that is, the measurement point density can be kept substantially constant. As a result, the spatial density of the obtained point cloud data becomes substantially constant, and the quality of forest measurement for the forest 54 on the slope 52 can be made uniform.

The above-mentioned flight method means that the altitude or true altitude represented by the first contour line 60a and the absolute altitude are kept constant at the same time for the first contour line 60a, and the second contour line 60b is for the second contour line 60b. It means flying while keeping the altitude or true altitude and the absolute altitude constant at the same time.

Therefore, the above flight method can be paraphrased as follows. That is, the method of performing forest measurement is (i) to scan the forest on the slope with a LiDAR sensor while flying the unmanned aerial vehicle at a predetermined absolute altitude and a predetermined first true altitude, and (ii) to perform the unmanned aerial vehicle at a predetermined altitude. The LiDAR sensor is used to scan the forest again while flying at an absolute altitude and a predetermined second true altitude different from the predetermined first true altitude.

The present inventor further studied a suitable forest measurement method for making the quality of forest measurement uniform. As a result, it was found that the unmanned helicopter 1 was flown as follows. The method of mounting the LiDAR sensor on the unmanned helicopter 1 is as described above.

Other forest measurement methods found by the present inventor are (i) using a LiDAR sensor to emit while changing the emission direction of a pulse at a predetermined angular pitch to measure the surrounding space, and (ii) up to a slope. The distance is L, the flight speed of the unmanned helicopter 1 is V, the number of laser pulses emitted simultaneously in the same angular direction is N, the frequency of the laser pulses emitted in the same angular direction is f, and the predetermined angular pitch is α. At that time, perform forest measurement for the forest on the slope using the LiDAR sensor while flying an unmanned aircraft so that the relative value of α ・ L with respect to V / (f ・ N) falls within a predetermined range. Including.

Here, "α · L" is the distance between the two arrival positions when the two laser pulses emitted at intervals of a predetermined angle pitch α reach the ground surface separated by a distance L. Further, V / f of "V / (f · N)" is the next one laser from the same emission port one cycle after one laser pulse is emitted from the emission port of the LiDAR sensor. This is the distance that the unmanned helicopter 1 flies during the minute time until the pulse is emitted. This distance means the distance between the two arrival positions when these two laser pulses reach the ground surface. When N laser pulses are emitted at the same time, N laser pulses reach between two positions separated by a distance of V / f. That is, it can be said that "V / (f · N)" is the average distance between two adjacent arrival positions among the N arrival positions.

That is, the meaning of "the relative value of α / L with respect to V / (f / N) is within a predetermined range" is relative to the interval (A) of the laser pulses incident on the ground surface with respect to the flight direction of the unmanned helicopter 1. It means that the relative value of the interval (B) of the laser pulses incident on the ground surface with respect to the direction perpendicular to the traveling direction is within a predetermined range. An example of a "predetermined range" is when the "relative value" is represented by a ratio B / A or a ratio A / B, the ratio is in the range 0.9 to 1.1, which is wider 0.8. The range may be from 1.3 to 1.3, and may be a wider range of about 0.5-2.0. If the range is wide, the analysis accuracy will decrease with respect to the amount of data during analysis, and it is expected that the calculation efficiency will deteriorate. However, a range having a value less than 0.5 and / or a value greater than 2.0 as a boundary value may be adopted. A person skilled in the art can set an appropriate ratio range in consideration of analysis accuracy, calculation efficiency, and the like. The "relative value" can also be defined by using the difference between the interval (A) and the interval (B) described above. However, the magnitude of the "difference" can vary greatly depending on the conditions under which the LiDAR sensor 20 is operating and / or the flight speed and the like. Therefore, the example of "within a predetermined range" regarding the difference is omitted.

When the ratio is 1 or the difference is 0, it means that the above-mentioned interval (A) and interval (B) are equal. At this time, the measurement point group is distributed in a square mesh shape or a grid shape, and a substantially uniform measurement point density can be ensured. Whether the relative values are expressed as ratios or differences, the specific values of V / (f · N) and α · L can be determined from the required measurement point densities.

The "L" of "α ・ L" is shorter as it is closer to the bottom of the unmanned helicopter 1, and becomes larger as it is farther from the unmanned helicopter 1. Therefore, the distance to the ground surface at the position or direction in which the desired measurement point density is desired may be set as "L". An example of the "direction" referred to here is a direction 45 degrees from the vertical downward direction on the plane assuming a plane perpendicular to the flight direction of the unmanned helicopter 1 in flight.

Refer to Fig. 2. When the unmanned helicopter 1 is stationary on flat ground, it takes X, Y and Z axes as shown. It is assumed that the positive direction of the X-axis is the direction from the front to the back of the paper. The + Y direction is the traveling direction of the aircraft 4 during flight, the + Z direction is vertically upward, and the −Z direction is vertically downward.

The unmanned helicopter 1 is equipped with an airframe 4 having a main body 2 and a tail body 3. A LiDAR sensor 20 is attached to the front of the machine 4 (in the + Y direction) and below the body 4 (in the −Z direction). A main rotor 5 is provided above the main body 2 (in the + Z direction), and a tail rotor 6 is provided at the rear of the tail body 3. A radiator 7 is provided at the front portion of the main body 2. An engine, an intake system, a main rotor shaft, and a fuel tank (not shown) are housed in the main body 2.

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 on 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 16 which is a leg that supports the aircraft 4 at the time of landing is provided on the lower side of the central portion of the main body 2.

The flight control box 15 is mounted on the main body 2.

FIG. 4 shows an example of the hardware configuration of the flight control box 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 such as a ROM 15h and a RAM 15i. The components 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 a 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 may be plural (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 barometric pressure sensor 15c detects the 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. 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 has a communication circuit that performs wireless communication conforming to the Bluetooth (registered trademark) and / or Wi-Fi (registered trademark) standard. 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 path data includes contour line and absolute altitude data that the unmanned helicopter 1 should fly along.

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 on the unmanned helicopter 1 from a recording medium (semiconductor memory, optical disk, etc.) on which it is recorded, or may be downloaded via a telecommunication line such as the Internet. You may also install such a computer program on the unmanned helicopter 1 via wireless communication. Such computer programs may be sold as packaged software.

The signal processing circuit 15g executes the 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 speed and throttle opening, and performs the unmanned helicopter 1 along a flight path prepared in advance. Let it fly.

In this embodiment, the flight control box 15 is connected to the LiDAR sensor 20. The flight control box 15 may provide the LiDAR sensor 20 with position data indicating the flight position of the unmanned helicopter 1 acquired by the GPS module 15a, for example. As a result, the LiDAR sensor 20 can use, for example, geographic coordinates by using the position data and the scan result (a set of time data, direction data, and distance data) at the time of scanning even if the LiDAR sensor 20 itself does not mount the GPS module 15a. The position represented by the system can be calculated.

The operator who manages the flight and operation of the unmanned helicopter 1 can also fly the unmanned helicopter 1 along the flight route prepared in advance while visually observing the flight state. At the rear end of the tail body 3, a remote control receiving antenna 23 for receiving a command signal from the remote control pilot is provided.

Refer to Fig. 2 again. The LiDAR sensor 20 is an optical device that measures the distance to a reflection point by, for example, emitting a near-infrared laser pulse 22 and detecting the reflected light of the laser pulse 22.

In an exemplary embodiment, the LiDAR sensor 20 is of a mechanical rotation type, and can scan 360 degrees in all directions by rotating a detector that detects a laser and reflected light of a laser pulse. However, in the present embodiment, the scannable range of the LiDAR sensor 20 that is blocked by the aircraft 4 of the unmanned helicopter 1, for example, the range of ± 60 degrees (120 degrees in total) centered on the + Z direction of the LiDAR sensor 20 is measured. Not reflected in the result.

One laser pulse may be emitted for each rotation in a certain angle direction, or a plurality of laser pulses may be emitted at the same time. FIG. 2 shows how N laser pulses 22 are emitted at the same time. However, for convenience of description, it is described in a beam shape instead of a pulse shape. An example of N is 12. When N is 2 or more, the LiDAR sensor 20 is provided with N laser pulse outlets.

A laser pulse emitted from a certain outlet will be described with reference to FIG. The LiDAR sensor 20 rotates while changing the direction at predetermined angular pitch α (rad) to emit the laser pulse 22, and detects the reflected light of each laser pulse 22. As a result, it is possible to obtain data on the distance to the reflection point in the direction for each predetermined angular pitch α. When the number of pulses emitted per unit time of the LiDAR sensor 20 is M and the number of rotations per unit time is R for one outlet, the predetermined angle pitch α is α (rad) = 2.π · R / M. Desired.

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. 2). 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.

FIG. 5 shows an unmanned helicopter 1 that uses a LiDAR sensor 20 to perform forest measurement on a forest 54 on a slope 52. Each straight line extending radially from the unmanned helicopter 1 schematically represents each laser pulse 22 as in FIG. Each laser pulse 22 reciprocates between the LiDAR sensor 20 and the reflection point along each straight line. In the following, the forest 54 on the slope 52 will be referred to as "slope forest 54".

The unmanned helicopter 1 is programmed to fly along a flight path determined by the method described below. By flying in the flight path, the laser pulse emitted from the LiDAR sensor 20 reaches not only the canopy of the slope forest 54 but also the trunk and is reflected. For example, paying attention to the tree 56 constituting the slope forest 54, the laser pulse 22 hits both the canopy 56a and the trunk 56b of the tree 56. Not only the laser pulse emitted below the horizontal direction but also the laser pulse emitted in the horizontal direction and the laser pulse 22 emitted above the horizontal direction are incident on the trunk 56b. .. This makes it possible to measure the canopy and trunk of trees in forests, especially slope forests 54. The "horizontal direction" here means a direction in which a plane (horizontal plane) orthogonal to the vertical direction spreads when the unmanned helicopter 1 is flying in the posture shown in FIG. The position of the horizontal plane in the vertical direction is the position of the outlet of the LiDAR sensor 20. In addition, "above the horizontal direction" is also referred to as "diagonally upward direction" except for vertically upward direction (directly upward direction). Furthermore, "below the horizontal direction" is also referred to as "diagonally downward direction" except for the vertical downward direction (directly downward direction). The "diagonal upward direction" and the "diagonal downward direction" are also collectively referred to as the "diagonal direction".

The LiDAR sensor 20 is mounted on the unmanned helicopter 1 so that its rotation axis (or swing axis) 20a faces the traveling direction of the body 4 of the unmanned helicopter 1. "The rotation axis or the swing axis faces the traveling direction of the machine body 4" includes that the rotation axis or the swing axis is parallel to the Y axis, but it does not have to be strictly parallel to the Y axis. If the rotation axis or the swing axis is in a direction parallel to the YZ plane, for example, and is within a predetermined angle range from the traveling direction of the machine body 4, the rotation axis or the swinging axis is in the traveling direction of the machine body 4. It can be said that it is suitable. An example of the "predetermined angle range" is a range of ± 30 degrees from the traveling direction of the aircraft 4. The reason for allowing such a mounting method is that the unmanned helicopter 1 can fly with the nose side slightly lowered (forward leaning attitude).

Furthermore, it is not essential that the direction is "parallel to the YZ plane" in the above example. This is because it is possible to measure the forest even if it deviates in the + X direction or the -X direction. That is, the rotation axis or the swing axis of the LiDAR sensor 20 should be in the "direction parallel to the YZ plane" and in the "direction not parallel to the YZ plane" as long as it is within the range where the forest meter v measurement can be performed. You may turn to it.

FIG. 6 shows a modified example of the mounting position of the LiDAR sensor 20. The LiDAR sensor 20 is mounted so as to be surrounded by a lower portion near the center of the body 4 of the unmanned helicopter 1 and a skid 16. The description of the rotation axis or the swing axis of the LiDAR sensor 20 is the same as the example of FIG. In the example of FIG. 6, the orientation of the attached LiDAR sensor 20 is opposite to that of the example of FIG. However, also in the example of FIG. 6, it can be said that the rotation axis or the swing axis faces the traveling direction of the machine body 4.

In the case of the installation example of FIG. 6, the skid 16 of the unmanned helicopter 1 enters the scan range of the LiDAR sensor 20. Therefore, the LiDAR sensor 20 always detects the distance to the skid. The distance to the position of other reflection points may be calculated without reflecting the reflected light from the skid in the measurement result.

The LiDAR sensor 20 may be provided at the lower part of the tail body 3 in order to prevent the skid 16 of the unmanned helicopter 1 from entering the scanning range of the LiDAR sensor 20. Also in this case, the description of the rotation axis or the swing axis of the LiDAR sensor 20 is the same as the example of FIG.

The forest measurement method in the exemplary embodiment will be described below.

FIG. 7A is a perspective view showing a part of the flight path 60 in the exemplary embodiment, and FIG. 7B is a top view showing a part of the flight path 60. For convenience of explanation, the description of the forest 54 on the slope 52 of the mountain 50 is omitted.

The flight path can include many segments. 7A and 7B show some of the many segments. Specifically, it is a path segment that flies along the first contour line 60a and a path segment that flies along the second contour line 60b. In the present embodiment, a large number of route segments flying along the contour lines are set, and forest measurement is performed for the forest in the observation target area. The route segment of such a flight path 60 may be set by an operator who manages the flight and operation of the unmanned helicopter 1. When moving from the route segment along the first contour line 60a to the route segment along the second contour line 60b, the unmanned helicopter 1 flies, for example, along the route segment 60c that descends the slope in the direction perpendicular to the contour line. The route segment 60c may also be set by the operator, or is automatically set by a tablet computer, a base station control device, or the like described later after setting the route segment along the first contour line 60a and the route segment along the second contour line 60b. May be done. The explanation of the long broken line 60d shown in FIG. 7B will be described later.

FIG. 8 is a cross-sectional view of a slope 52 showing an unmanned helicopter 1 flying along the first contour line 60a and an unmanned helicopter 1 flying along the second contour line 60b. The cross section is along the AA line of FIGS. 7A and 7B.

The absolute altitude (AGL) that the unmanned helicopter 1 flies is constant (AGL = Ha) in both cases on the first contour line 60a and the second contour line 60b. The horizontal offset of the first contour line 60a and the second contour line 60b is D.

FIG. 8 shows that the true altitude (MSL) of the unmanned helicopter 1 flying along the second contour line 60b is Hm. In the example of FIG. 8, the true altitude Hm is substantially the same as the altitude indicated by the first contour line 60a. Therefore, it is understood that the laser pulse emitted from the LiDAR sensor 20 of the unmanned helicopter 1 flying along the second contour line 60b is incident on the trunk of a tree (not shown) near the first contour line 60a at a right angle. To. This makes it possible to measure the canopy and trunk of the LiDAR sensor 20.

Note that the measurement target area may include the edge of the forest 54. In that case, in determining the flight path 60, a flight path that passes over a position separated by a predetermined distance in the direction of the non-forest area from the end of the forest 54 may be adopted. An example of the “position separated by a predetermined distance” is the long broken line 60d shown in FIG. 7B. When such a flight path is adopted, the trunks of the trees at the end of the forest 54 are located diagonally downward to the right or diagonally downward to the left in the direction of travel of the unmanned helicopter 1. This makes it possible to scan the trunks of trees at the edges of the forest 54 using the LiDAR sensor 20 and acquire a point cloud of reflection points.

Here, other advantages of maintaining the absolute altitude Ha constant will be described with reference to FIGS. 9A and 9B.

FIG. 9A shows the distribution of laser pulses incident on the slope 52 when the absolute altitude AGL is constant (AGL = Ha). FIG. 9B shows the distribution of laser pulses incident on the slope 52 when the true altitude MSL is maintained constant (MSL = Hm). In both figures, the unmanned helicopter is flying from the back to the front or from the front to the back of the paper.

When the absolute altitude AGL is maintained constant (Fig. 9A), the distance between the unmanned helicopter 1 and the slope 52 is almost constant regardless of which contour line the flight is along. As a result, the measurement point density of the laser pulse reaching the slope 52 from the LiDAR sensor 20 can be maintained substantially constant.

On the other hand, when the true altitude MSL is maintained constant (Fig. 9B), the more the unmanned helicopter 1 flies along the lower contour line, the farther the unmanned helicopter 1 is from the slope 52. As a result, the density of measurement points on the slope 52 decreases. That is, it is difficult to make the measurement point density uniform.

Therefore, it is preferable to keep the absolute altitude Ha constant in order to make the measurement point density uniform.

FIG. 10 shows the results of forest measurement performed by the method according to the exemplary embodiment. Forest measurement was performed on forests on slopes similar to the slopes illustrated in FIG. As shown in FIG. 10, it is understood that not only the canopy of each tree in the forest but also the trunk is measured. From the obtained results, the present inventor confirmed that the forest measurement method according to the present embodiment is effective.

The operator can set the flight path 60 in which the contour lines and the absolute altitude are specified as described above 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 "forest measurement system".

FIG. 11A shows an example of a forest measurement system 100 including an unmanned helicopter 1 and a tablet computer 70. FIG. 11B also shows an example of a forest 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 contour line data 90 described later is stored in the storage device. The tablet computer 70 and the base station control device 80 display the contour line 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 designation of contour lines (route segments) to fly the unmanned helicopter 1 and designation of absolute altitude by 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. 11A will be described as an example. 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. 12 shows an example of the hardware configuration of the tablet computer 70.

The tablet computer 70 has 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 a 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. Also, 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, a flash memory) for storing contour 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 the computer program into RAM, and executes the program.

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 (registered trademark) standard and / or the Wi-Fi standard, and communicates with the unmanned helicopter 1 on a one-to-one basis. To 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 uses the contour line data 90 to display an image of the mountain 50 in which the contour lines are exemplified, and the flight path on the display 75 in response to the touch operation of the operator received via the touch screen panel 76. Draw 60.

The touch screen panel 76 can detect the operator's touch made with a finger, a pen, or the like. As the detection method, an electrostatic type, a resistive film type, an optical type, an ultrasonic method, an electromagnetic type and the like are known. For example, in the case of the capacitance type 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 sent data. An example of "data on change" is data on the position where the capacitance changed and the time length changed.

"Touch" includes various operations such as short press (or tap), long press, and slide. For example, a short press is an operation in which the operator touches the touch screen panel 76 with a finger and then releases the finger within a predetermined reference time. The long press is an operation in which the operator touches the touch screen panel 76, maintains the state without moving the finger, and releases the finger after a time longer than the reference time has elapsed.

In the present embodiment, the touch screen panel 76 is provided so as to be superimposed on the display 75. The operator touches the desired contour line image while looking at the mountain 50 and contour line image 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. As a result of the determination, the CPU 71 can determine the position of the contour line associated with the image displayed at the position. 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.

FIG. 13 shows an example of contour line data 90 in the observation target area read into the memory 72. The contour data may be prepared for each fixed altitude (for example, every 10 m). The contour line data does not have to be the image data as shown in FIG. 13, and it is sufficient that the elevation data and the coordinate data are related to each other. In the present specification, "contour line data" may be referred to as "information about contour lines".

When the operator specifies between a contour line (first contour line) and an adjacent contour line (second contour line), the CPU 71 of the tablet computer 70 can calculate the elevation of the specified position. For example, let the elevation of the first contour line be Z1 and the elevation of the second contour line be Z2. It is assumed that the operator specifies the position W that divides the area between the first contour line and the second contour line into W1: W2. Using the proportional relationship, the altitude of the position W can be expressed as (W1, Z2 + W2, Z1) / (W1 + W2). In this way, the CPU 71 can extract an altitude at a designated arbitrary position and a contour line connecting a plurality of points having the altitude. The CPU 71 may present the extracted contour line candidates to the operator.

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

FIG. 14 is a flowchart showing a procedure of flight path setting processing according to an exemplary embodiment. The procedure shown in FIG. 14 is executed under the control of the CPU 71 (FIG. 12) of the tablet computer 70 or the base station control device 80. When a plurality of observation target areas can be selected, one of them is assumed to be specified in advance.

In step S2, the CPU 71 acquires information on contour lines related to the observation target area.

In step S4, the CPU 71 accepts the designation of contour lines via the touch screen panel 76. Various methods for designating contour lines can be considered. For example, the operator short-presses and specifies a plurality of positions on the desired contour lines displayed on the tablet computer 70. The order specified can be the order of the flight transit points of the unmanned helicopter 1. As another example, when the operator presses and holds a certain position on the map displayed on the tablet computer 70, the CPU 71 of the tablet computer 70 determines the altitude corresponding to the touched position. The CPU 71 extracts a plurality of positions having a determined altitude and automatically displays contour lines connecting them. By touching the displayed contour line, the operator can specify the flight path along the contour line as a route segment. If the operator presses and holds a position at a different elevation, a new contour line may be determined and a route segment may be added in the same procedure. As yet another example, the CPU 71 may automatically extract and display a plurality of contour lines in the observation target area. If approval is obtained from the operator, each contour line may be set as a route segment and one flight route may be determined.

In step S6, the CPU 71 determines whether or not the contour line setting is completed. For example, the CPU 71 repeats the processes of steps S4 and S6, assuming that the contour line setting is not completed, until the operator receives an input indicating that the contour line setting is completed. On the other hand, when the input indicating that the contour line setting is completed is received, the CPU 71 determines that the contour line setting 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. 11A, a “+” button for increasing the absolute altitude value and a “−” button for decreasing the absolute altitude value are displayed. The software keyboard may be displayed so that numerical values can be directly input, or numerical values may be input using a GUI such as a dial or a slider.

By the above processing, the flight path 60 (FIGS. 7A and 7B) 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 according to the procedure shown in FIGS. 15 and 16.

FIG. 15 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 under the control of 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 is started on the contour line of the flight path 60. 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 contour lines and at the set absolute altitude. The details of the process in step S14 will be described later with reference to FIG.

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 has flown along the preset flight path 60. 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.

FIG. 16 shows the details of the process of step S14 in FIG.

In step S140, the signal processing circuit 15g detects the flight position (latitude and longitude) and altitude (elevation). For example, the signal processing circuit 15g uses the output of the GPS module 15a to detect the flight position, and uses the output of the barometric pressure sensor 15c to detect the altitude.

In step S142, the signal processing circuit 15g determines whether or not the amount of deviation from the contour line is within the first predetermined value. The "deviation amount" represents the distance from the current flight position to the contour line. An example of the "first predetermined value" is 10 m. If the deviation amount is within the first predetermined value, the process proceeds to the next step S146, and if the deviation amount is not within the first predetermined value, the process proceeds to step S144.

In step S144, the signal processing circuit 15g corrects the flight position so that the deviation amount is within the first predetermined value. As a result, the flight position of the unmanned helicopter 1 approaches the contour line.

In the next step S146, the signal processing circuit 15g determines whether or not the deviation amount of the absolute altitude is within the second predetermined value. The "absolute altitude deviation amount" represents the difference between the absolute altitude at the current flight position and the preset absolute altitude. The absolute altitude at the current flight position is the difference between the altitude at the current flight position and the altitude of the contour line of the set flight path. An example of the "second predetermined value" is 10 m.

If the absolute altitude deviation amount is within the second predetermined value, the process proceeds to step S16 (FIG. 15). If the deviation amount is not within the predetermined value, the process proceeds to step S148.

In step S148, the signal processing circuit 15g corrects the current absolute altitude so that the deviation amount of the absolute altitude is within the second predetermined value.

In this embodiment, the unmanned helicopter 1 flies along the contour lines. By flying along the contour lines, fluctuations in the distance to the ground surface and / or the surface layer of the canopy can be suppressed. Since it is not necessary to frequently raise and lower the unmanned helicopter 1 to keep the distance to the ground surface and / or the surface layer of the canopy constant, energy consumption can be reduced and the cruising range can be increased. it can.

In addition, in the forest measurement targeting the forest 54 on the slope 52, the point cloud data on the opposite side of the slope 52 is unnecessary. Therefore, the point cloud data on the opposite side of the slope 52 may not be stored in the storage device. As a result, the amount of data at the time of analyzing the point cloud data can be reduced, and the analysis speed can be improved. The point cloud data on the opposite side of the slope 52 may not be stored in the storage device 15j of the unmanned helicopter 1, or may not be stored in the memory 72 of the tablet computer 70, for example. Further, when analyzing the point cloud data with the tablet computer 70 or another computer, only the point cloud data on the slope 52 side may be used. As a result, the analysis speed can be improved.

One of the advantages of flying the unmanned helicopter 1 along the contour line while maintaining the absolute altitude constant was that the density of measurement points on the slope 52 could be maintained substantially constant. The present inventor has investigated a further flight method for maintaining the measurement point density substantially constant.

FIG. 17 shows the slope 52 of the mountain 50 scanned by the unmanned helicopter 1 in flight. For convenience of explanation, the description of forest is omitted. A broken line is shown on the slope 52. Each point constituting the broken line schematically and schematically shows the incident position of the laser pulse. Further, FIG. 18 is a diagram for explaining the relationship between the two sides constituting the region S in FIG. Although the region S is represented by a rectangle in FIGS. 17 and 18, this is an ideal shape when there is no phase shift for emitting a laser pulse, disturbance during flight, or the like. The area S is not always rectangular.

Let Δt be the time required for the LiDAR sensor 20 to make one rotation. Between a certain time t and a time t + Δt, the LiDAR sensor 20 emits laser pulses radially in a plane approximately perpendicular to the flight direction of the unmanned helicopter 1. Each laser pulse is incident one after another at the position where the above-mentioned plane and the slope 52 intersect.

On the other hand, since the unmanned helicopter 1 is flying, the position of the unmanned helicopter 1 changes during the period Δt during which the LiDAR sensor 20 makes one rotation. Between the time t + Δt after the position change and the next time t + 2Δt, the LiDAR sensor 20 makes one rotation again and emits a laser pulse radially. As a result, these laser pulses are incident at a position slightly deviated in the traveling direction from the incident position of the laser pulse incident on the slope 52 between the time t and the time t + Δt. As the unmanned helicopter 1 continues to fly, the laser pulses incident on the slope 52 will be distributed in a mesh or grid pattern. The position where the laser pulse is incident (incident point) is the reflection position (reflection point) of the laser pulse.

The region S shown in the partially enlarged view is a region surrounded by the incident points a _k , a _{k + 1} , b _k , and b _{k + 1 of} four adjacent laser pulses incident on the slope 52 between the time t and the time t + 2Δt. The incident points a _k and a _{k + 1} indicate the incident points of two laser pulses adjacent to each other in the laser pulse group emitted between the time t and the time t + Δt. The LiDAR sensor 20 emits these two laser pulses with a predetermined angle pitch α open (FIG. 18). The incident points b _k and b _{k + 1} indicate the incident points of two laser pulses adjacent to each other in the laser pulse group emitted between the time t + Δt and the time t + 2Δt.

The incident point a _k and the incident point b _k are the incident points of the two laser pulses emitted from the LiDAR sensor 20 in the same angular direction with a time interval Δt. The relationship between the incident point a _{k + 1} and the incident point b _{k + 1} is also the same.

The above description assumes that the number of laser pulses emitted from the LiDAR sensor 20 at a certain time is one. However, as shown in FIG. 2, there is also a LiDAR sensor 20 that has N emission ports and can simultaneously emit N laser pulses 22 from each emission port. Even in such a case, the above description can be applied to the laser pulse emitted from each outlet.

See FIG. Let Zd be the distance between the incident points a _k and a _{k + 1} (or the distance between the incident points b _k and b _{k + 1} ), and the distance between the incident points a _k and b _k (or the distance between the incident points a _{k + 1} and b _{k + 1).} ) Is Yd. _{Considering the} case where the region S is not rectangular, the distance Zd means the distance on the XZ plane when the incident points a _k and a _{k + 1} are projected onto the XZ plane perpendicular to the Y direction. Further, the distance Yd means the distance between the incident points a _k and b _k along the Y direction or the distance on the YZ plane when the incident points a _k and b _k are projected on the YZ plane perpendicular to the X direction. To do.

The flight speed of the unmanned helicopter 1 is V (m / s), the number of laser pulses emitted simultaneously in the same angular direction is N, the frequency of the laser pulses emitted in the same angular direction is f (Hz), and the predetermined angular pitch is set. Let L (m) be the distance from the α (rad) and LiDAR sensor 20 to the incident point _ak . "Laser pulses emitted at the same angle direction", for example, represent the two laser pulses incident on the incident point b _k and the incident point a _k described above. In the following, these values may be referred to as "parameters".

Using the above parameters, the interval Yd can be expressed as V / f. There are N incident points between the intervals Yd. If the distance between two adjacent incident points is yd, yd can be expressed as V / (f · N). The interval Zd is approximated to α · L.

The present inventor has determined that if the interval Zd and the interval yd are equalized, the density of measurement points in the scanning direction of the LiDAR sensor 20 and the density of measurement points in the flight direction of the unmanned helicopter 1 can be kept constant. However, the intervals Zd and yd need not be exactly equal. Therefore, the present inventor used the LiDAR sensor 20 to target the forest on the slope 52 while flying the unmanned helicopter 1 so that the relative values of α and L with respect to V / (f ・ N) fall within a predetermined range. It was decided to carry out forest measurement. The "relative value of α / L with respect to V / (f / N)" here can be expressed by a ratio or a difference. As described with reference to FIG. 1, an example of a "predetermined range" is in the range 0.9 to 1.1 when the "relative value" is expressed as a ratio, which is a wider range of 0.8. It may be in the range of 1.2 to 1.2, or it may be in a wider range of about 0.5-2.0. At this time, the measurement point cloud is distributed in a substantially square mesh or grid shape. As a result, it is possible to secure a substantially uniform measurement point density.

The above parameters V, N, f, α and L can all be variable values. For example, the flight speed V of the unmanned helicopter 1 is clearly a variable value. The parameters N, f and α can also be changed according to the specifications of the LiDAR sensor 20 and / or by being set by the operator. The distance L can be arbitrarily set as a distance to the ground surface at a position or direction in which a desired measurement point density is desired to be secured. The flight speed V of the unmanned helicopter 1 can be autonomously adjusted by the signal processing circuit 15g of the unmanned helicopter 1. On the other hand, the parameters N, f, α and L can be preset or specified by the operator operating the tablet computer 70 or the base station control device 80 of the forest measurement system 100 (FIGS. 11A and 11B) described above. The parameters N, f, α and L can be stored in the storage device 15j of the unmanned helicopter 1. The parameter L may be adjusted autonomously by the signal processing circuit 15g of the unmanned helicopter 1. It is also a category of the forest measurement system 100 to accept necessary parameters and have the unmanned helicopter 1 perform forest measurement while adjusting the flight speed and the like according to the parameters.

The smaller the V / (f · N) and α · L values, the higher the measurement point density. Therefore, for example, when the predetermined angle pitch α is variable, it is conceivable to fix it to the minimum possible value. At this time, the flight speed V may be reduced and / or the frequency f and / or the number N may be increased within a range that does not interfere with the flight.

When the LiDAR sensor 20 is a mechanical rotation type, when the number of pulse emissions per unit time is M and the rotation speed per unit time is R, the predetermined angle pitch α is α (rad) = 2.π · R ·. Obtained by N / M. Therefore, the above-mentioned parameter α may be replaced as follows. That is, the unmanned helicopter 1 may be flown to perform forest measurement so that the relative values of (2, π, R, N / M), and L with respect to V / (f, N) fall within a predetermined range. ..

FIG. 19 is a flowchart showing a processing procedure for making the measurement point density uniform by changing the parameters. The procedure shown in FIG. 19 is executed under the control of the signal processing circuit 15 g (FIG. 4) of the unmanned helicopter 1 after the unmanned helicopter 1 arrives in the airspace where the forest measurement is performed.

In step S20, the signal processing circuit 15g starts forest measurement using the LiDAR sensor 20.

In step S22, the signal processing circuit 15g detects the flight speed V of the current unmanned helicopter 1 and the distance L to the position where the desired measurement point density is desired. For example, the signal processing circuit 15g may obtain the flight speed V by obtaining the movement amount per unit time by using the output of the GPS module 15a. Alternatively, the signal processing circuit 15g may acquire the flight speed V by time-integrating the acceleration in the flight direction using the output of the acceleration sensor 15b. Further, the signal processing circuit 15g acquires the distance L from the output of the LiDAR sensor 20 to the position where the desired measurement point density is desired to be secured.

In step S24, the signal processing circuit 15g determines whether or not the relative value of α / L with respect to V / (f · N) (hereinafter abbreviated as “relative value”) is within a predetermined range. The "predetermined range" may be set by the operator prior to flight. The signal processing circuit 15g may hold each value of the parameters f, N, α set by the operator in the RAM 15i or the like, or may acquire the parameters f, N, α from the LiDAR sensor 20 in real time. Good. If the relative value is within the predetermined range, the process proceeds to step S28, and if the relative value is not within the predetermined range, the process proceeds to step S26.

In step S26, the signal processing circuit 15g adjusts at least one of V, f, N, α, and L. For example, when the parameters f, N, α, and L are fixed during flight, the signal processing circuit 15g adjusts the flight speed V of the unmanned helicopter 1.

In step S28, the signal processing circuit 15g determines whether or not the forest measurement to be performed has been completed. The signal processing circuit 15g repeatedly executes the processes after step S22 until the forest measurement is completed.

FIG. 20 is a flowchart showing a specific example of the process shown in FIG. In FIG. 20, steps S30, S32, S34 and S36 which are more specific steps S24 and S26 of FIG. 19 are provided. Hereinafter, steps S30 to 36 will be described.

In step S30, the signal processing circuit 15g determines whether or not the relative value is equal to or greater than the lower limit value Qmin. If the relative value is less than the lower limit value Qmin, the process proceeds to step S32, and if the relative value is more than the lower limit value Qmin, the process proceeds to step S34.

In step S32, the signal processing circuit 15g reduces the flight speed V of the unmanned helicopter 1 and / or increases the distance L. After that, the process returns to step S30.

In step S34, the signal processing circuit 15g determines whether or not the relative value is less than the upper limit value Qmax. If the relative value is less than the lower limit value Qmin, the process proceeds to step S28, and if the relative value is equal to or more than the upper limit value Qmax, the process proceeds to step S36.

In step S36, the signal processing circuit 15g increases the flight speed V of the unmanned helicopter 1 and / or decreases the distance L. After that, the process returns to step S30.

According to the above processing, by adjusting the parameters V and / or L so that the relative value falls within a predetermined range, the measurement point density in the flight direction and the scan direction can be made uniform.

Next, a method of irradiating the measurement object such as the forest 54 with the laser pulse 22 evenly will be described.

The laser pulse 22 emitted from the LiDAR sensor 20 irradiates the object to be measured to form a laser spot on the surface of the object to be measured. The laser pulse 22 emitted from the LiDAR sensor 20 travels while diverging at a predetermined divergence angle even when the laser beam is collimated. Therefore, the size of the laser spot formed on the measurement target increases in proportion to the distance between the LiDAR sensor 20 and the measurement target. When the distance between the LiDAR sensor 20 and the measurement target is shortened, the size of the laser spot formed on the measurement target becomes smaller.

For example, if the distance between the LiDAR sensor 20 and the measurement target is shortened in order to measure the measurement target in detail, the size of the laser spot formed on the measurement target becomes smaller. As the size of the laser spots becomes smaller, a gap is created between the laser spots adjacent to each other. When measuring the forest, we want to irradiate not only the canopy but also the trunk and the ground surface with the laser pulse 22. In order to prevent the laser spot from removing the gap between the leaves, it is desirable to irradiate the forest with the laser pulse 22 without a gap.

FIG. 21 is a diagram schematically showing a plurality of laser pulses 22 emitted from the LiDAR sensor 20 when the unmanned helicopter 1 in flight is viewed from the front.

FIG. 21 shows the

laser pulses

22a, 22b, and 22c as the laser pulse 22. Area indicated by a dot pattern sandwiched by the solid line in FIG. 21 represents a single laser pulse 22a which travels while diverging at a divergence angle theta _1. The region indicated by the dot pattern sandwiched by the broken line represents a single laser pulse 22b that travels while diverging at a divergence angle θ ₁ . The region represented by the dot pattern sandwiched by the alternate long and short dash line represents a single laser pulse 22c that travels while diverging at a divergence angle θ ₁ .

FIG. 22 is a diagram schematically showing a plurality of laser pulses 22 emitted from the LiDAR sensor 20 when the unmanned helicopter 1 in flight is viewed from the side.

FIG. 22 shows

laser pulses

22a, 22i, and 22p as the laser pulse 22. The region indicated by the dot pattern sandwiched by the solid line in FIG. 22 represents a single laser pulse 22a that travels while diverging at a divergence angle θ ₂ . The region indicated by the dot pattern sandwiched by the broken line represents a single laser pulse 22i that travels while diverging at a divergence angle θ ₂ . The region represented by the dot pattern sandwiched by the alternate long and short dash line represents a single laser pulse 22p that travels while diverging at a divergence angle θ ₂ . The divergence angles θ ₁ and θ ₂ of the laser pulse 22 are predetermined by the specifications of the LiDAR sensor 20 and are fixed values.

21 and 22 show an example in which the measurement object 51 is a flat ground surface in order to explain the present embodiment in an easy-to-understand manner, but the measurement object 51 is not limited thereto. For example, the measurement object 51 may be a slope 52, a forest 54, or a forest 54 (slope forest) on the slope 52.

FIG. 23 is a diagram showing a laser spot formed on the measurement object 51 by the laser pulse 22. FIG. 23 shows a laser spot 24a formed on the measurement object 51 by the laser pulse 22a, a laser spot 24b formed on the measurement object 51 by the laser pulse 22b, and a laser spot 22c formed on the measurement object 51 by the laser pulse 22c. The laser spot 24c is shown. FIG. 23 further shows a laser spot 24i formed on the measurement object 51 by the laser pulse 22i and a laser spot 24p formed on the measurement object 51 by the laser pulse 22p. In the present embodiment, the cross-sectional shape of the laser pulse 22 along the plane in the direction perpendicular to the traveling direction of the laser pulse 22 is substantially rectangular. Therefore, the shape of the laser spot 24 formed by the laser pulse 22 is also substantially rectangular.

The shape of the laser spots 24 is not limited to a rectangle, but in order to efficiently arrange the laser spots 24 in a plane without gaps, the shapes of the individual laser spots 24 must have a rectangular shape or a substantially rectangular shape. However, it is preferable as compared with the case where it has an elliptical shape, for example. The laser spot 24 may have any shape by adjusting the shape of the light emitting region of the laser light source (typically an array of semiconductor laser elements).

As described above with reference to FIG. 3, the LiDAR sensor 20 emits the laser pulse 22 while changing the emission direction of the laser pulse 22 at a predetermined angle pitch α. With reference to FIG. 21, the laser pulse 22a is a laser pulse emitted from one outlet of the LiDAR sensor 20. The laser pulse 22b is a laser pulse emitted from the same outlet at the timing when the LiDAR sensor 20 is rotated by an angle α from the timing when the laser pulse 22a is emitted. The laser pulse 22c is a laser pulse emitted from the same outlet at the timing when the LiDAR sensor 20 is further rotated by an angle α.

Each of the

laser pulses

22a, 22b, and 22c diverges at a divergence angle θ ₁ in a direction perpendicular to the rotation axis 20a (FIGS. 21 and 22) of the LiDAR sensor 20. In the present embodiment, the predetermined angle pitch α of the LiDAR sensor 20 is adjusted to be smaller than the divergence angle θ ₁ . As a result, as shown in FIG. 21, the laser pulse 22a and the laser pulse 22b can be overlapped on the plane (ZX plane) perpendicular to the rotation axis 20a of the LiDAR sensor 20. Further, the laser pulse 22b and the laser pulse 22c can be overlapped with each other. That is, the laser spot 24a (FIG. 23) formed on the measurement object 51 by the laser pulse 22a and the laser spot 24b formed on the measurement object 51 by the laser pulse 22b can be overlapped with each other. The laser spot 24b and the laser spot 24c formed on the measurement object 51 by the laser pulse 22c can be overlapped with each other. In FIG. 23, the relationship between the angle pitch α and the divergence angle θ ₁ is virtually shown on the laser spot.

Next, a method of overlapping the laser spots in the aircraft traveling direction (flight direction) of the unmanned helicopter 1 will be described. With reference to FIG. 22, the laser pulse 22a is a laser pulse emitted from one outlet of the LiDAR sensor 20. The laser pulse 22i is a laser pulse emitted from the same outlet at the timing when the LiDAR sensor 20 makes one rotation from the timing when the laser pulse 22a is emitted. The laser pulse 22p is a laser pulse emitted from the same outlet at the timing when the LiDAR sensor 20 rotates one more time.

The laser pulse 22a diverges at a divergence angle θ ₂ in a plane parallel to both the aircraft traveling direction 201 and the emission direction of the laser pulse 22a. The laser pulse 22i diverges at a divergence angle θ ₂ in a plane parallel to both the aircraft traveling direction 201 and the emission direction of the laser pulse 22i. The laser pulse 22p diverges at a divergence angle θ ₂ in a plane parallel to both the aircraft traveling direction 201 and the emitting direction of the laser pulse 22p. Each of the

laser pulses

22a, 22i, and 22p diverging at the divergence angle θ ₂ forms a laser spot on the measurement object 51. In the example shown in FIG. 22, the length of each laser spot in the direction parallel to the aircraft traveling direction 201 is represented by K. Further, the flight distance that the unmanned helicopter 1 flies while the LiDAR sensor 20 makes one rotation is represented by J.

Since the length K of the laser spot is proportional to the distance L between the LiDAR sensor 20 and the object to be measured 51, the length K of the laser spot can be grasped if the distance L is known. The distance L is, for example, the absolute altitude H. As described above, the absolute altitude H can be detected using a barometric pressure sensor 15c, a LiDAR sensor 20, a radio altimeter, or the like. Further, as described above, the absolute altitude H may be the distance from the ground surface or the distance from the surface layer of the canopy.

In the present embodiment, the flight speed V of the unmanned helicopter 1, the rotation speed R of the LiDAR sensor 20 per unit time, and the unmanned helicopter so that the flight distance J of the unmanned helicopter 1 is shorter than the length K of the laser spot 24. Adjust at least one of the altitudes H of 1. For example, the flight speed V of the unmanned helicopter 1 is adjusted so that the flight distance J is shorter than the length K. As a result, in the aircraft traveling direction 201 of the unmanned helicopter 1, the laser spot 24a (FIG. 23) formed on the measurement object 51 by the laser pulse 22a and the laser spot formed on the measurement object 51 by the laser pulse 22i. The 24i can be overlapped, and the laser spot 24i and the laser spot 24p formed on the measurement object 51 by the laser pulse 22p can be overlapped.

With reference to FIGS. 22 and 23, the laser spot 24j is a laser spot formed by a laser pulse emitted from the same emission port at a timing when the LiDAR sensor 20 is rotated by an angle α from the timing when the laser pulse 22i is emitted. Is. The laser spot 24k is a laser spot formed by a laser pulse emitted from the same outlet at a timing when the LiDAR sensor 20 is further rotated by an angle α. The laser spot 24q is a laser spot formed by a laser pulse emitted from the same outlet at a timing when the LiDAR sensor 20 is rotated by an angle α from the timing when the laser pulse 22p is emitted. The laser spot 24r is a laser spot formed by a laser pulse emitted from the same outlet at a timing when the LiDAR sensor 20 is further rotated by an angle α.

In the present embodiment, the flight distance J is made shorter than the length K of the laser spot, and the predetermined angle pitch α is made smaller than the divergence angle θ ₁ of the laser pulse 22. As a result, as shown in FIG. 23, the laser spots can be overlapped with each other in both the airframe traveling direction 201 of the unmanned helicopter 1 and the direction perpendicular to the airframe traveling direction 201. By overlapping the laser spots, the laser pulse 22 can be evenly applied to the measurement target object 51, and the measurement target object 51 can be measured in detail.

As described above, the LiDAR sensor 20 has N exit ports arranged along the direction in which the rotation shaft 20a extends, and can simultaneously emit a maximum of N laser pulses 22. In the above description, the length K of the laser spot 24 is the length of the laser spot formed by one laser pulse emitted from one emission port, but it is emitted from two or more emission ports at the same time. It may be the length of the laser spot formed by two or more laser pulses. In this case, the laser spots formed by each of the two or more laser pulses emitted at the same time overlap to form one laser spot as a whole. The length K is the length of one laser spot formed from the two or more laser pulses. In this case as well, the laser spots can be overlapped with each other in both the airframe traveling direction 201 and the direction perpendicular to the airframe traveling direction 201 of the unmanned helicopter 1.

FIG. 24 is a flowchart showing a forest measurement procedure performed while irradiating the forest 54, which is an example of the measurement object 51, with the laser pulse 22 evenly.

In step S40, the predetermined angle pitch α is adjusted so that the predetermined angle pitch α becomes smaller than the divergence angle θ ₁ of the laser pulse 22. The adjustment of the predetermined angle pitch α is executed, for example, by the CPU 71 (FIG. 12) of the tablet computer 70.

As described above, the predetermined angle pitch α is represented by α = 2.π · R / M. The divergence angle θ ₁ is a fixed value known in advance. The CPU 71 adjusts the predetermined angle pitch α so as to be smaller than the divergence angle θ ₁ by changing at least one of the number of times the laser pulse 22 is emitted M and the number of rotations R of the LiDAR sensor 20 per unit time. To do. For example, by changing the rotation speed R, the predetermined angle pitch α is made smaller than the divergence angle θ ₁ . The operator may set the predetermined angle pitch α by inputting the value of the predetermined angle pitch α into the tablet computer 70 before the flight.

Next, in step S42, the CPU 71 sets at least one of the flight speed V, the rotation speed R, and the altitude H so that the flight distance J of the unmanned helicopter 1 is shorter than the length K of the laser spot 24. adjust. For example, the flight speed V is adjusted so that the flight distance J is shorter than the length K. When adjusting the rotation speed R, adjust within a range in which the relationship of α <θ ₁ can be maintained.

For example, when the range of the value taken by the distance L between the LiDAR sensor 20 and the forest 54 is set in advance at the time of forest measurement, the range of the value taken by the length K of the laser spot 24 can be grasped in advance. it can. For example, before the flight, the operator inputs the range of values taken by the distance L to the tablet computer 70. The CPU 71 calculates the lower limit value of the range of values taken by the length K from the range of values taken by the distance L. The CPU 71 sets the calculated lower limit value as the value of the length K used for comparison with the flight distance J. The operator may set the value of the length K used for comparison with the flight distance J by inputting the value of the length K into the tablet computer 70 before the flight. The CPU 71 sets, for example, the flight speed V so that the flight distance J is shorter than the set length K.

Next, in step S44, forest measurement is started. Forest measurement is performed by any of the procedures described with reference to FIGS. 15 and 16, the procedures described with reference to FIGS. 19 and 20, or a combination of these procedures.

During forest measurement, the CPU 71 compares the flight distance J with the length K (step S46). When the CPU 71 determines that the flight distance J is less than the length K, the CPU 71 continues the forest measurement (step S48). The process of step S46 is repeated until the forest measurement is completed (step S52).

When it is determined in step S46 that the flight distance J is the length K or more, the CPU 71 determines that the flight distance J is shorter than the length K at least among the flight speed V, the rotation speed R, and the altitude H. Adjust one (step S50). For example, the flight distance J is adjusted to be shorter than the length K by performing at least one of lowering the flight speed V, increasing the rotation speed R, and increasing the altitude H. For example, by lowering the flight speed V, the flight distance J is made shorter than the length K. When increasing the rotation speed R, adjust within a range in which the relationship of α <θ ₁ can be maintained. When increasing the altitude H, the distance L is adjusted so that it can be maintained within a preset range. After the adjustment, the process of step S46 is executed again.

By executing the above processing, it is possible to measure the forest while irradiating the forest 54 with the laser pulse 22 evenly.

Note that the distance L between the LiDAR sensor 20 and the forest 54 may be measured during the forest measurement, and the length K may be calculated from the measured distance L. For example, the distance L can be calculated from the difference between the emission time of the laser pulse 22 and the acquisition time of the reflection pulse of the laser pulse 22. Since the length K is proportional to the distance L, the length K can be calculated from the distance L.

In the above description, the processing of steps S40, S42, S46 and S50 is executed by the CPU 71, but the signal processing circuit 15g (FIG. 4) of the unmanned helicopter 1 may execute the processing. Further, these processes may be shared by the CPU 71 and the signal processing circuit 15 g.

According to the present 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 flying by an internal combustion engine 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 equipped 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 on a slope.

LiDAR sensors, radar ranging devices such as millimeter waves, antennas and imaging devices (cameras) can be called "observers". In the above-described embodiment, the LiDAR sensor has been illustrated as an observer, but other observers may be mounted on an unmanned aerial vehicle. In this case, mountains, forests, slopes, flat lands, etc. observed using an observer are "observation target areas". For example, when a camera is mounted on an unmanned aerial vehicle, the flight method illustrated in the above embodiment is suitable for searching for a victim on a slope. The light acquired by the camera at the time of shooting corresponds to the reflected pulse from the reflection point acquired by the LiDAR sensor. When an unmanned aerial vehicle is flown by the above-mentioned flight method, it is possible to take an image including a victim of the slope with a camera while maintaining a general distance from the slope. Therefore, the victim can be searched precisely. Since the camera does not emit a laser pulse like LiDAR, the camera does not have a rotation axis or a swing axis. The camera may be mounted on an unmanned aerial vehicle so that the field of view of the camera includes at least the slopes of the forest.

Furthermore, equipment different from the observer may be mounted on the unmanned aerial vehicle. An example of such a device is a drug sprayer. Unmanned aerial vehicles have already been used to spray chemicals such as herbicides and pesticides. Chemicals may be sprayed on sloped forests for forest management and utilization. At that time, the spraying target area is determined, and the chemical is sprayed on the slope by the spraying device while the unmanned aerial vehicle is flying in the spraying target area by the above-mentioned flight method. Then, the drug can be sprayed at a substantially uniform density while maintaining the distance from the slope. Since the spraying device does not emit a laser pulse like LiDAR, the spraying device does not have a rotation axis or a swing axis. The sprayer may be mounted on an unmanned aerial vehicle so that the sprayer sprays the drug at least on the slopes of the forest.

In the above description of the embodiment, the target of forest measurement is mainly the forest 54 on the slope 52, but the target of forest measurement is not limited to that. The target of forest measurement may be a flat forest.

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

As described above, the method according to an embodiment of the present invention is a method in which an unmanned aerial vehicle 1 equipped with a lidar (LiDAR) sensor 20 is flown to perform forest measurement on a slope forest 54. The rotation shaft 20a or the swing shaft 20a of the sensor 20 is mounted on the unmanned aerial vehicle 1 so as to face the traveling direction of the aircraft, and (i) while flying the unmanned aerial vehicle 1 along the first contour line 60a at a predetermined absolute altitude. , Scan the forest 54 with the rider sensor 20, and (ii) fly the unmanned aerial vehicle 1 along the second contour line 60b, which is different from the first contour line 60a, at a predetermined absolute altitude, while the rider sensor 20 scans the forest 54. Perform a scan again.

In certain embodiments, the method may further include pre-specifying the first contour lines 60a, the second contour lines 60b and a predetermined absolute altitude prior to steps (i) and (ii).

In certain embodiments, the method further comprises having the rider sensor 20 scan the end of the forest 54 while the unmanned aerial vehicle 1 is flying over a predetermined distance from the end. You may.

In certain embodiments, the rider sensor 20 may scan the canopy and trunk of each tree in the forest 54.

In certain embodiments, steps (i) and (ii) may include causing the rider sensor 20 to scan the forest 54 using a horizontally emitted laser pulse 22.

In certain embodiments, steps (i) and (ii) may include causing the rider sensor 20 to scan the forest 54 using a laser pulse 22 emitted in an oblique direction.

In certain embodiments, the unmanned aerial vehicle 1 may be an unmanned helicopter or an unmanned multicopter.

A method according to an embodiment of the present invention is a method of determining a flight path of an unmanned aerial vehicle 1 equipped with an observer 20, in which the observation target area by the observer 20 is specified, and the observation target area includes a slope. , Determining a plurality of route segments in which the unmanned aerial vehicle 1 flies at a predetermined absolute altitude along any of the contour lines by referring to the contour data in the observation target area, and determining a flight route including a plurality of route segments. To do, to do.

In certain embodiments, determining a plurality of path segments may include setting a plurality of transit points on one or more selected contour lines and specifying an absolute altitude.

In some embodiments, the observation area may include a slope forest 54.

In certain embodiments, the observer 20 may be a lidar (LiDAR) sensor 20.

In certain embodiments, determining the flight path may include determining a flight path at the edge of the forest 54 that passes over a predetermined distance from the edge.

In certain embodiments, the observer 20 may be an infrared camera.

A method according to an embodiment of the present invention is a method in which an unmanned aerial vehicle 1 equipped with a lidar (LiDAR) sensor 20 is flown to perform forest measurement targeting a forest 54 on a slope, and the rotation axis of the rider sensor 20. The 20a or the swing axis 20a is mounted on the unmanned aerial vehicle 1 so as to face the traveling direction of the aircraft, and (i) the unmanned aerial vehicle 1 is flying at a predetermined absolute altitude and a predetermined first true altitude while riding the forest 54. The forest 54 is driven by the rider sensor 20 while scanning with the sensor 20 and (ii) flying the unmanned aerial vehicle 1 at a predetermined absolute altitude and a predetermined second true altitude different from the predetermined first true altitude. To scan again.

The forest measurement system 100 according to an embodiment of the present invention has an unmanned aircraft 1 and a computer device 70, and is a forest measurement system for flying an unmanned aircraft 1 to perform forest measurement for a slope forest 54. 100, the unmanned aircraft 1 has a lidar (LiDAR) sensor 20, a first signal processing circuit 15g, a first storage device 15j, and a first communication circuit 15f, and the rotation shaft 20a of the rider sensor 20. Alternatively, the swing shaft 20a is mounted on the unmanned aircraft 1 so as to face the traveling direction of the aircraft, and the computer device 70 stores information on the display device 75, the input device 76, the second signal processing circuit 71, and the contour lines. The second storage device 72 and the second communication circuit 73 are provided, and the second signal processing circuit 71 acquires information on the contour line from the second storage device 72, and the first contour line 60a, via the input device 76, The designation of the second contour line 60b and the absolute altitude is accepted, and the designated first contour line 60a, the second contour line 60b and the absolute altitude data are transmitted to the unmanned aircraft 1 via the second communication circuit 73, and the first signal processing is performed. The circuit 15g receives the data of the first contour line 60a, the second contour line 60b and the absolute altitude via the first communication circuit 15f, and receives the received first contour line 60a, the second contour line 60b and the absolute altitude data first. Stored in the storage device 15j, while flying the unmanned aircraft 1 along the first contour line 60a at absolute altitude, the forest 54 is scanned by the rider sensor 20, and the unmanned aircraft 1 is flown along the second contour line 60b at absolute altitude. The rider sensor 20 scans the forest 54 again.

The imaging method according to an embodiment of the present invention is a method of photographing an observation target by using an unmanned aerial vehicle 1 provided with an image pickup device 20, and when the observation target area is specified and the observation target area includes a slope. To determine a plurality of route segments in which the unmanned aerial vehicle 1 flies at a predetermined absolute altitude along any of the contour lines by referring to the contour data in the observation target area, and to determine a flight route including a plurality of route segments. , While flying the unmanned aerial vehicle 1 along the determined flight path, the image pickup device 20 performs imaging.

The spraying method according to an embodiment of the present invention is a method of spraying a drug using an unmanned aerial vehicle 1 provided with a drug spraying device 20, wherein the spraying device 20 specifies an area to be sprayed, and the spraying target area is When including a slope, refer to the contour data in the area to be sprayed to determine a plurality of route segments in which the unmanned aerial vehicle 1 flies at a predetermined absolute altitude along any of the contour lines, and a flight including a plurality of route segments. The route is determined, and the drug is sprayed while the unmanned aerial vehicle 1 is flying along the determined flight route.

A computer program according to an embodiment of the present invention is a computer program for causing a computer to control forest measurement for a slope forest 54 performed by flying an unmanned aircraft 1 equipped with a lidar (LiDAR) sensor 20. The rotation shaft 20a or the swing shaft 20a of the rider sensor 20 is mounted on the unmanned aircraft 1 so as to face the traveling direction of the aircraft, and the computer program determines (i) the unmanned aircraft 1 along the first contour line 60a. The forest 54 is scanned by the rider sensor 20 while flying at the absolute altitude of, and (ii) the unmanned aircraft 1 is flown at a predetermined absolute altitude along the second contour line 60b different from the first contour line 60a. The rider sensor 20 causes the computer to control the scanning of the forest 54 again.

A method according to an embodiment of the present invention is a method in which an unmanned aerial vehicle 1 equipped with a lidar (LiDAR) sensor 20 is flown to perform forest measurement targeting a forest 54, and the rotation axis 20a of the lidar sensor 20 or The rocking shaft 20a is mounted on the unmanned aerial vehicle 1 so as to face the traveling direction of the aircraft, and the lidar sensor 20 is used to emit the laser pulse 22 while changing the emission direction at a predetermined angular pitch to measure the surrounding space. The distance to the forest 54 is L, the flight speed of the unmanned aerial vehicle 1 is V, the number of laser pulses 22 emitted simultaneously in the same angular direction is N, and the frequency of the laser pulses 22 emitted in the same angular direction is f. When the predetermined angle pitch is α, the forest 54 is operated by using the lidar sensor 20 while flying the unmanned aerial vehicle 1 so that the relative values of α and L with respect to V / (f ・ N) are within the predetermined range. Perform the forest measurement of interest.

In a certain embodiment, the predetermined angle pitch α may be a fixed value.

In a certain embodiment, the lidar sensor 20 is a mechanical rotation type, and the number of times the laser pulse 22 is emitted per unit time at one outlet for emitting the laser pulse 22 is M, and the number of rotations per unit time is R. Then, the predetermined angle pitch α is obtained by α (rad) = 2.π · R / M, and the forest measurement is performed by (2 · π · R / M) · L with respect to V / (f · N). It may include flying the unmanned aerial vehicle 1 so that the relative value falls within a predetermined range.

In a certain embodiment, the number of emission times M per unit time and the number of rotations R per unit time may be variable values.

In one embodiment, the lidar sensor 20 is of a mechanical rotation system, the predetermined angle pitch α is smaller than the divergence angle θ _{1 in the} direction perpendicular to the rotation axis 20a of the laser pulse 22, and in the above method, the rider sensor 20 is 1. The flight speed V of the unmanned aircraft 1 is such that the flight distance J that the unmanned aircraft 1 flies while rotating is shorter than the length K in the direction parallel to the traveling direction of the aircraft at the laser spot 24 formed in the forest 54. It may include adjusting at least one of the number of revolutions R of the rider sensor 20 per unit time and the altitude H of the unmanned aircraft 1.

In a certain embodiment, the above method changes the divergence angle θ ₁ by changing at least one of the number of times M and the number of revolutions R of the pulse emitted per unit time at one outlet for emitting the laser pulse 22. May include adjusting the predetermined angle pitch α so that

In certain embodiments, the forest 54 may be a sloped forest.

The forest measurement system 100 according to an embodiment of the present invention is a forest measurement system 100 having an unmanned aircraft 1 and a computer device 70, for flying the unmanned aircraft 1 and performing forest measurement for the forest 54. The unmanned aircraft 1 has a lidar (LiDAR) sensor 20, a first signal processing circuit 15g, a storage device 15j, and a first communication circuit 15f, and has a rotation shaft 20a or a rotation shaft 20a of the rider (LiDAR) sensor 20. The rocking shaft 20a is mounted on the unmanned aircraft 1 so as to face the traveling direction of the aircraft, and the computer device 70 includes a display device 75, an input device 76, a second signal processing circuit 71, and a second communication circuit 73. The second signal processing circuit 71 has the number N of laser pulses 22 simultaneously emitted in the same angular direction, the frequency f of the laser pulses 22 emitted in the same angular direction, and a predetermined value via the input device 76. The designation of the angle pitch α is accepted, and the data of the specified number N, the frequency f and the predetermined angle pitch α are transmitted to the unmanned aircraft 1 via the second communication circuit 73, and the first signal processing circuit 15g is the first. The data of the number N, the frequency f and the predetermined angle pitch α are received via the communication circuit 15f, the received data of the number N, the frequency f and the predetermined angle pitch α are stored in the storage device 15j, and the distance to the forest 54. Let L be, and let V be the flight speed of the unmanned aircraft 1, then the unmanned aircraft 1 is flown so that the relative value of α · L with respect to V / (f · N) falls within a predetermined range, and the rider sensor 20 Is used to measure the forest of the forest 54.

A computer program according to an embodiment of the present invention is a computer program that causes

computers

15 and 70 to control forest measurement for a forest 54 performed by flying an unmanned aircraft 1 equipped with a lidar (LiDAR) sensor 20. Therefore, the rotation shaft 20a or the swing shaft 20a of the lidar sensor 20 is mounted on the unmanned aircraft 1 so as to face the traveling direction of the aircraft, and the computer program uses the lidar sensor 20 to determine the emission direction of the laser pulse 22. Emit while changing at a predetermined angle pitch to measure the surrounding space, the distance to the forest 54 is L, the flight speed of the unmanned aircraft 1 is V, and the number of laser pulses 22 simultaneously emitted in the same angle direction is N. When the frequency of the laser pulse 22 emitted in the same angular direction is f and the predetermined angular pitch is α, the relative value of α ・ L with respect to V / (f ・ N) falls within the predetermined range. The

computers

15 and 70 are made to control the forest measurement for the forest 54 by using the lidar sensor 20 while flying the aircraft 1.

The technique of the present invention can be suitably used when performing forest measurement, searching for victims, spraying chemicals, etc. on forests, especially forests on slopes.

1: Unmanned helicopter, 4: Aircraft, 15: Flight control box, 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, 22: Laser pulse, 50: Mountain, 52: Slope, 54: Forest (slope forest), 60: Flight path , 60a: 1st contour line (path segment), 60b: 2nd contour line (path segment), 60c: 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: Contour line data, 100: Forest measurement system

Claims

It is a method of flying an unmanned aerial vehicle equipped with a lidar (LiDAR) sensor to perform forest measurement on a forest on a slope, and the rotation axis or swing axis of the lidar sensor is directed toward the traveling direction of the aircraft. Onboard the aircraft
(I) The unmanned aerial vehicle is made to scan the forest with the rider sensor while flying along the first contour line at a predetermined absolute altitude, and (ii) the unmanned aerial vehicle is different from the first contour line. A method of performing rescanning of the forest with the rider sensor while flying along the contour lines at the predetermined absolute altitude.
The method according to claim 1, further comprising pre-designating the first contour line, the second contour line, and the predetermined absolute altitude before the steps (i) and (ii).
At the edge of the forest, claim 1 or 2, further comprising scanning the edge with the rider sensor while flying the unmanned aerial vehicle over a position a predetermined distance away from the edge. The method described.
The method according to any one of claims 1 to 3, wherein the rider sensor scans the canopy and trunk of each tree in the forest.
The method according to any one of claims 1 to 4, wherein the steps (i) and (ii) include causing the rider sensor to scan the forest using a laser pulse emitted in the horizontal direction.
The method according to any one of claims 1 to 5, wherein the steps (i) and (ii) include causing the rider sensor to scan the forest using a laser pulse emitted in an oblique direction.
The method according to any one of claims 1 to 6, wherein the unmanned aerial vehicle is an unmanned helicopter or an unmanned multicopter.
A method of determining the flight path of an unmanned aerial vehicle equipped with an observer.
Identifying the observation target area with the observer,
When the observation target area includes a slope, the contour data in the observation target area is referred to to determine a plurality of route segments in which the unmanned aerial vehicle flies at a predetermined absolute altitude along any of the contour lines, and Determining a flight path that includes the plurality of path segments,
How to do it.
Determining the plurality of route segments is
Setting multiple transit points on one or more selected contour lines, and
The method of claim 8, comprising designating the absolute altitude.
The method according to claim 8 or 9, wherein the observation target area includes a forest on the slope.
The method according to claim 10, wherein the observer is a lidar (LiDAR) sensor.
The method according to claim 10 or 11, wherein determining the flight path includes determining the flight path that passes over a position separated from the end by a predetermined distance at the end of the forest.
The method according to claim 8, wherein the observer is an infrared camera.
It is a method of flying an unmanned aerial vehicle equipped with a lidar (LiDAR) sensor to perform forest measurement on a forest on a slope, and the rotation axis or swing axis of the lidar sensor is directed toward the traveling direction of the aircraft. Onboard the aircraft
(I) The unmanned aerial vehicle is made to scan the forest with the rider sensor while flying at a predetermined absolute altitude and a predetermined first true altitude, and (ii) the unmanned aerial vehicle is operated at the predetermined absolute altitude and the said. A method of rescanning the forest with the rider sensor while flying at a predetermined second true altitude different from the predetermined first true altitude.
It is a forest measurement system that has an unmanned aerial vehicle and a computer device, and allows the unmanned aerial vehicle to fly to perform forest measurement for forests on slopes.
The unmanned aerial vehicle
With a lidar sensor,
The first signal processing circuit and
The first storage device and
It has a first communication circuit, and the rotation axis or swing axis of the rider sensor is mounted on the unmanned aerial vehicle so as to face the traveling direction of the aircraft.
The computer device
Display device and
Input device and
The second signal processing circuit and
A second storage device that stores information about contour lines,
Has a second communication circuit
The second signal processing circuit
Information about the contour lines is acquired from the second storage device,
The designation of the first contour line, the second contour line and the absolute altitude is accepted via the input device.
The designated first contour line, the second contour line, and the absolute altitude data are transmitted to the unmanned aerial vehicle via the second communication circuit.
The first signal processing circuit
Data of the first contour line, the second contour line, and the absolute altitude are received via the first communication circuit.
The received first contour line, the second contour line, and the absolute altitude data are stored in the first storage device.
While flying the unmanned aerial vehicle along the first contour line at the absolute altitude, the forest is scanned by the rider sensor.
The rider sensor scans the forest again while flying the unmanned aerial vehicle along the second contour line at the absolute altitude.
Forest measurement system.
It is a method of photographing an observation target using an unmanned aerial vehicle equipped with an imaging device.
Identifying the observation target area,
When the observation target area includes a slope, the contour data in the observation target area is referred to to determine a plurality of route segments in which the unmanned aerial vehicle flies at a predetermined absolute altitude along any of the contour lines.
Determining a flight path that includes the plurality of path segments,
An imaging method in which the unmanned aerial vehicle is made to fly along a determined flight path and photographed by the imaging device.
It is a method of spraying chemicals using an unmanned aerial vehicle equipped with a chemical spraying device.
Identifying the area to be sprayed by the spraying device,
When the area to be sprayed includes a slope, the contour data in the area to be sprayed is referred to to determine a plurality of route segments in which the unmanned aerial vehicle flies at a predetermined absolute altitude along any of the contour lines.
Determining a flight path that includes the plurality of path segments,
A spraying method that performs spraying of a drug while flying the unmanned aerial vehicle along a determined flight path.
A computer program that allows a computer to control forest measurements for forests on slopes by flying an unmanned aerial vehicle equipped with a lidar sensor.
The rotation axis or swing axis of the rider sensor is mounted on the unmanned aerial vehicle so as to face the traveling direction of the aircraft.
The computer program
(I) The unmanned aerial vehicle is made to scan the forest with the rider sensor while flying along the first contour line at a predetermined absolute altitude, and (ii) the unmanned aerial vehicle is different from the first contour line. A computer program that causes the computer to control the rescanning of the forest with the rider sensor while flying along the contour lines at the predetermined absolute altitude.