JP7347130B2 - Fresnel zone inspection method and obstacle detection system used therein - Google Patents

Description

The present invention relates to a method for inspecting a Fresnel zone formed between a pair of wireless communication antennas arranged oppositely, and in particular, to efficiently inspect whether or not an obstacle to wireless communication exists in the Fresnel zone. The present invention relates to a Fresnel zone inspection method that can be used to inspect a Fresnel zone, and an obstacle detection system used therein.

In order to reduce power loss and ensure communication line quality in microwave wireless communications, it is necessary to prevent obstacles from entering a certain range between the transmitting antenna and the receiving antenna, called the Fresnel zone. be. It goes without saying that the antenna should be installed in a location where there are no obstacles in the Fresnel zone, but trees, high-rise buildings, or construction cranes that grow after the antenna is installed may invade the Fresnel zone. There are cases.

FIG. 7 is a diagram schematically showing a Fresnel zone.
As shown in FIG. 7, Fresnel zone 51 is an area formed between antennas 52a and 53a of base station 52 and fixed station 53. Note that, assuming that the positions of the antennas 52a and 53a are P ₁ and P ₂ , respectively, the radius H of the Fresnel zone 51 at the point P on the line segment P ₁ P ₂ is expressed by the following equation (1). However, λ is the wavelength of radio waves used for wireless communication. Further, n is a dimensionless number, and the larger n is, the larger the radius H of the Fresnel zone 51 is. Further, d ₁ and d ₂ are the lengths of line segment PP ₁ and line segment PP ₂ , respectively.

When there is a possibility that an obstacle 54 such as a tree exists inside the Fresnel zone 51, confirmation thereof has conventionally been performed visually. However, this method requires estimating the position of the other antenna using a compass from one side of the antennas 52a and 53a and imagining the range of the Fresnel zone 51, which is actually invisible. However, with this method, it is difficult to accurately determine the presence of an obstacle in the Fresnel zone 51.

Regarding a technique for detecting the presence or absence of an obstacle in a Fresnel zone between two wireless communication antennas, for example, Patent Document 1 discloses an invention entitled "Communication Area Inspection Device."
The invention disclosed in Patent Document 1 includes a test condition input section for inputting test conditions such as location information of two opposing stations such as a base station and a fixed station that perform wireless communication and the frequency of radio waves to be used; A Fresnel zone calculation unit calculates the Fresnel zone between two stations based on the inspection conditions, a site information search unit searches for the site directly under the calculated Fresnel zone by referring to the map database, and There is a building information search section that searches for building information for buildings on the site by referring to a construction application database that stores building information for which construction applications have been submitted, and a Fresnel The structure includes an obstacle determination section that determines whether there are any buildings that may enter the zone.
According to such a configuration, not only before the antenna is installed, but also after the antenna is installed, buildings that may fall into the above-mentioned Fresnel zone are identified based on information on the group of buildings that are planned to be newly constructed. It is possible to determine the presence or absence of

Furthermore, Patent Document 2 describes a measurement system for three-dimensional measurement of industrial products and an unmanned controllable system used in the measurement system, which is entitled "Measurement system for determining 3D coordinates of the surface of a target object." Disclosed is an invention relating to an automotive aircraft and a method for determining 3D coordinates used in performing 3D measurements in the measurement system.
The automobile aircraft disclosed in Patent Document 2 is configured to be able to fly along a predetermined route and is equipped with a scanning device that can be controlled unmanned. Then, the specification states that the surface of the object is scanned by a scanning beam emitted from a scanner of a scanning device, local measurement coordinates of each position on the surface are determined, and measurement points on the object are determined by a laser tracker. It is described that the 3D coordinates of the object are formed by reference to the object coordinate system.
When an automobile/aircraft having such a structure is used, even if the object is installed in a place that cannot be easily approached, the 3D coordinates of the object can be easily obtained.

Japanese Patent Application Publication No. 2005-192145 Special Publication No. 2014-513792

The invention disclosed in Patent Document 1, which is the prior art described above, can be applied to artificially created obstacles such as buildings from which necessary information can be obtained, but it cannot be applied to actual obstacles such as trees. The problem was that it could not be applied to detecting obstacles because the necessary information could not be obtained without going to the site and conducting an investigation.

The invention disclosed in Patent Document 2 uses an unmanned controllable flying object called an automobile aircraft to easily obtain 3D coordinates of objects located in locations that humans cannot approach. However, there was a problem in that it was difficult to apply in cases where the flight path of the aircraft was restricted, such as in the Fresnel zone.

The present invention has been made in response to such conventional circumstances, and provides a Fresnel zone inspection method that can efficiently inspect whether or not an obstacle to wireless communication exists in the Fresnel zone. The object of the present invention is to provide an obstacle detection system for use in the present invention.

In order to achieve the above object, a first invention is an obstacle detection system used for inspecting a Fresnel zone between a pair of wireless communication antennas disposed oppositely, the obstacle detection system detecting an obstacle in the Fresnel zone. An obstacle detection device that acquires position information of a measurement target that can be an object and converts it into three-dimensional coordinate values; a Fresnel zone calculation device that acquires three-dimensional coordinate values of a Fresnel zone; An obstacle determination device that determines whether a measurement object corresponds to an obstacle by comparing dimensional coordinate values, and control that controls the operation of the obstacle detection device, Fresnel zone calculation device, and obstacle determination device. The obstacle detection device includes an unmanned flying vehicle, a communication unit, and a calculation unit, and the unmanned flying vehicle is a laser measuring device that measures the distance to a measurement target using laser light. A distance device, a holder that holds the laser distance measuring device so that the direction of laser beam irradiation can be changed, a position information acquisition unit that acquires current position information based on a GNSS signal received from a GNSS satellite, and a predetermined It is equipped with an aircraft storage unit in which a flight path is stored, and an aircraft control unit that controls a power mechanism and a steering mechanism so as to be able to fly along the flight path stored in this aircraft storage unit, and a calculation unit that uses a laser beam. The three-dimensional coordinate value of the object to be measured is calculated from the distance to the object to be measured by the distance measuring device and the current position information acquired by the position information acquisition section, and the obstacle determination device is connected to the communication section and the control device. In addition to receiving the 3D coordinate values of the measurement target via the It is characterized by determining that.

In an obstacle detection system having such a structure, among the ellipses that form an outline when the Fresnel zone is cut by a plane passing through the central axis, an ellipse that is orthogonal to the first vertical plane passing through the central axis, and , the Fresnel zone is created by adjusting the direction of the laser beam emitted from the laser range finder using the holder while flying the unmanned aerial vehicle by setting the flight path to a curve located below the plane passing through the central axis. When the laser beam is irradiated in the tangential direction of the boundary surface, the obstacle detection device has the effect of obtaining the three-dimensional coordinate values of the object to be measured near the lower boundary surface of the Fresnel zone.
In addition, if the object to be measured has entered the Fresnel zone, the laser beam is directed toward the intersection of the vertical line passing through the point where the object to be measured is irradiated with the laser beam and the boundary surface of the Fresnel zone. The irradiation has the effect that the obstacle detection device can obtain three-dimensional coordinate values of a portion of the object to be measured that has entered the Fresnel zone. The object to be measured is determined to be an obstacle by the obstacle determining device.

A second invention is based on the first invention, wherein the unmanned flying vehicle includes an attitude information acquisition section that acquires current flight attitude information, and the flight object storage section stores a predetermined flight attitude. , the power mechanism and the steering mechanism of the unmanned aerial vehicle are controlled by the aircraft control unit based on the current flight attitude information acquired by the attitude information acquisition unit and the flight attitude stored in the aircraft storage unit. This is a characteristic feature.
In the obstacle detection system having such a structure, instead of tilting the laser range finder using the holder, the unmanned flying vehicle is caused to fly with the flying vehicle control unit tilted at a predetermined angle, thereby achieving the first invention. A similar effect is exerted.

A third invention is a method for inspecting a Fresnel zone formed between a pair of wireless communication antennas disposed facing each other, comprising a step of calculating three-dimensional coordinate values of the Fresnel zone, and a step of calculating a three-dimensional coordinate value of the Fresnel zone, and The process of flying an unmanned flying vehicle equipped with a laser ranging device in a state where the irradiation direction can be changed along a predetermined flight path, and the measurement target that can become an obstacle to wireless communication in the Fresnel zone and unmanned flight. The process involves measuring the distance between the body using a laser range finder, acquiring the current position information of the unmanned flying vehicle, and calculating the three-dimensional coordinates of the object to be measured from this position information and the measurement results of the laser range finder. Compare the three-dimensional coordinate values of the object to be measured and the Fresnel zone, and measure if the three-dimensional coordinate values of the object to be measured are included in the range of three-dimensional coordinate values that indicate the inside of the Fresnel zone. determining the object as an obstacle, the unmanned aerial vehicle is configured to detect a first vertical line passing through the central axis of an ellipse that forms an outline when the Fresnel zone is cut by a plane passing through the central axis. The flight path is a curve that is perpendicular to the plane and located below the plane passing through the central axis, and after irradiating the laser beam in the tangential direction of the curve at the current position, the laser beam is irradiated onto the object to be measured. This method is characterized by irradiating the laser beam again toward the intersection of the first vertical line passing through the irradiated point and the boundary surface of the Fresnel zone.

In such a Fresnel zone inspection method, while the unmanned aerial vehicle is flown along the curved line, the holder adjusts the direction of the laser beam irradiated from the laser range finder. When a laser beam is irradiated forward parallel to the tangential direction of the current position of It has the effect of obtaining the three-dimensional coordinate values of the object to be measured located in front.
In addition, if the object to be measured has entered the Fresnel zone, the laser beam is directed toward the intersection of the vertical line passing through the point where the object to be measured is irradiated with the laser beam and the boundary surface of the Fresnel zone. The irradiation has the effect that the obstacle detection device can obtain three-dimensional coordinate values of a portion of the object to be measured that has entered the Fresnel zone. The object to be measured is determined to be an obstacle by the obstacle determining device.

A fourth invention is based on the third invention, wherein the unmanned aerial vehicle is located within an ellipse that forms an outline when the Fresnel zone is cut at a second vertical plane perpendicular to the first vertical plane at the current position. , after irradiating the laser beam in the tangential direction at the current position of the curve that is orthogonal to the first vertical plane and located below the plane passing through the central axis, the laser beam is irradiated onto the object to be measured. This method is characterized by irradiating the laser beam again toward the intersection of the second vertical line passing through the point and the boundary surface of the Fresnel zone.

In such a Fresnel zone inspection method, while flying the unmanned flying vehicle along the same flight path as in the third invention, a second vertical plane perpendicular to the first vertical plane passing through the central axis is Among the ellipses that form the contour line when the Fresnel zone is cut, the tangential direction at the current position of the unmanned aerial vehicle with respect to the curve that is perpendicular to the first vertical plane and located below the plane passing through the central axis. When the laser beam is irradiated on both sides in this direction, the obstacle detection device detects the object near the lower boundary surface of the Fresnel zone and in the left and right direction (direction perpendicular to the direction of travel) of the unmanned aerial vehicle. It has the effect of obtaining three-dimensional coordinate values of an existing measurement object.
In addition, if the object to be measured has entered the inside of the Fresnel zone, move the object toward the intersection of the second vertical line passing through the point where the object to be measured is irradiated with the laser beam and the boundary surface of the Fresnel zone. By irradiating the laser beam, the obstacle detection device has the effect of obtaining three-dimensional coordinate values of a portion of the object to be measured that has entered the Fresnel zone. The object to be measured is determined to be an obstacle by the obstacle determining device.

As explained above, in the first invention, laser light can be divided into two stages and irradiated in two different directions. Therefore, by using the first invention, it is possible to easily implement the Fresnel zone inspection method according to the third or fourth invention described below.

According to the second invention, the same effect as the first invention can be achieved by causing the unmanned flying vehicle to fly while being tilted at a predetermined angle by the flying vehicle control unit instead of tilting the laser range finder using the holder. Demonstrated.

According to the third invention, by irradiating the laser beam in two stages in a predetermined direction, the laser beam is located below the lower boundary surface of the Fresnel zone and in front of the unmanned aerial vehicle in the direction of travel. It is possible to clearly distinguish and detect whether a tree or the like has grown upward and invaded the Fresnel zone, or whether it has not reached the Fresnel zone.

According to the fourth invention, the same effects as the third invention can be achieved with respect to trees and the like that are below the lower boundary surface of the Fresnel zone and on the sides of the unmanned aerial vehicle.

1 is a block diagram showing the configuration of an obstacle detection system according to an embodiment of the present invention. (a) is a perspective view showing the appearance of the unmanned flying vehicle, and (b) is a block diagram showing the configuration of the unmanned flying vehicle. 1 is a flowchart showing an example of a procedure of a Fresnel zone inspection method according to an embodiment of the present invention. (a) and (b) are diagrams schematically showing a state in which an unmanned flying vehicle is flying from the fixed station side toward the base station side in FIG. 7. At the current position of the unmanned aerial vehicle shown _in FIG. 4, the Fresnel zone _shown in FIG. FIG. 3 is a diagram schematically showing a cut state. At the current position _of the unmanned aerial vehicle shown in FIG. 4, _the Fresnel zone shown in FIG. FIG. 3 is a diagram schematically showing a cut state. FIG. 3 is a diagram schematically representing a Fresnel zone.

The obstacle detection system of the present invention uses a small unmanned flying vehicle such as a drone to obtain three-dimensional coordinate values (X coordinate, Y coordinate, Z coordinate) of a measurement target existing within a wireless communication area. , when the three-dimensional coordinate value matches the three-dimensional coordinate value indicating the Fresnel zone, the measurement target object is determined to be an obstacle to wireless communication. Its configuration, operation, and effects will be specifically explained with reference to FIGS. 1 to 6.

FIG. 1 is a block diagram showing the configuration of an obstacle detection system according to an embodiment of the present invention. FIG. 2(a) is a perspective view showing the appearance of the unmanned flying vehicle, and FIG. 2(b) is a block diagram showing the configuration of the unmanned flying vehicle.
Note that the same reference numerals are given to the constituent elements already explained using FIG. 7, and the explanation thereof will be omitted as appropriate.

As shown in FIG. 1, an obstacle detection system 1 of the present invention includes an obstacle detection device 2 that acquires position information of a measurement target that can become an obstacle in a wireless communication zone and converts it into three-dimensional coordinate values, and a wireless The Fresnel zone calculation device 3 obtains the three-dimensional coordinate values of the Fresnel zone 51 within the communication area, and the three-dimensional coordinate values of the measurement object and the Fresnel zone are compared to determine whether the measurement object is an obstacle to wireless communication. The present invention includes an obstacle determination device 4 that determines whether or not an object is present, and a control device 5 that controls the operations of the obstacle detection device 2 to the obstacle determination device 4.

The obstacle detection device 2 consists of an unmanned aerial vehicle 6, a communication section 7, and a calculation section 8, and the Fresnel zone calculation device 3 detects the positions of the base station 52 and the fixed station 53, the sizes of the antennas 52a and 53a, etc. An input section 9 for inputting information and data such as the frequency of radio waves used; a storage section 10 for storing data related to the antenna inputted from the input section 9; and a storage section 10 for storing data stored in the storage section 10. It consists of a Fresnel zone calculation unit 11 that calculates the three-dimensional coordinate values of the Fresnel zone 51 using the above-mentioned equation (1). The obstacle determination device 4 includes a comparison calculation section 12 and an output section 13 that compare the three-dimensional coordinate values of the measurement object and the Fresnel zone.
Note that the storage unit 10 includes a RAM (Random Access Memory), a ROM (Read Only Memory), a nonvolatile memory, and the like. However, it is sufficient to include at least one of the RAM and nonvolatile memory. Further, the ROM stores data input from the input section 9 and programs and data used by the Fresnel zone calculation section 11, and the RAM and nonvolatile memory store calculation results by the Fresnel zone calculation section 11. Ru.

As shown in FIG. 2(a), the unmanned aerial vehicle 6 has a motor 15 installed at each tip, a plurality of arms 16 arranged radially to form the same plane, and rotation of the motor 15. A propeller 17 attached to a shaft, a main body frame 18 to which the base end of the arm 16 is connected, a laser distance measuring device 19 that measures the distance to an object using laser light, and a lower surface of the main body frame 18. a holder 20 that is installed in the main body frame 18 and holds the laser range finder 19 so as to be able to irradiate laser light in a predetermined direction; It is equipped with

The laser distance measuring device 19 is held by a holder 20 so as to be rotatable 360 degrees in a plane parallel to the plane formed by the plurality of arms 16 and rotatable at least 300 degrees in a plane perpendicular to the plane. ing.
That is, when the plane formed by the plurality of arms 16 is horizontal, the laser distance measuring device 19 can irradiate laser light in all directions in the horizontal direction, and can also irradiate the laser beam in all directions in the horizontal direction. Laser light can be irradiated within a rotation angle range of 300 degrees, including downward direction.

As shown in FIG. 2(b), the main body frame 18 includes a flight object control section 22, a flight object storage section 23, and a flight object for receiving GNSS (Global Navigation Satellite System) signals. A communication section 24, a position information acquisition section 25, an attitude information acquisition section 26, and an aircraft input section 14 for inputting information such as a predetermined flight route and flight attitude are installed.

The configuration of the aircraft storage section 23 is the same as the storage section 10 of the Fresnel zone calculation device 3. However, the flight object storage section 23 stores the current position information and attitude information of the unmanned aerial vehicle 6 obtained through processing in the position information acquisition section 25 based on the GNSS signal received from the GNSS satellite by the flight object communication section 24. Current flight attitude information obtained by section 26 is stored.
The aircraft control unit 22 uses the current position information and flight attitude information of the unmanned aircraft 6 acquired by the position information acquisition unit 25 and the attitude information acquisition unit 26, and the flight path stored in advance in the aircraft storage unit 23. and controls the power mechanism and steering mechanism of the unmanned aerial vehicle 6 based on the flight attitude. Thereby, the unmanned flying object 6 flies along a predetermined flight path while maintaining a predetermined flight attitude.

The calculation unit 8 of the obstacle detection device 2 uses the distance to the object to be measured measured by the laser range finder 19 of the unmanned aerial vehicle 6 and the current position information of the unmanned aerial vehicle 6 acquired by the position information acquisition unit 25. Based on this, the three-dimensional coordinate values of the object to be measured are calculated, and the results are sent from the communication section 7 to the control device 5.
The comparison calculation unit 12 of the obstacle determination device 4 compares the three-dimensional coordinate value of the measurement target object received via the control device 5 with the three-dimensional coordinate value of the Fresnel zone 51, and determines the three-dimensional coordinate value of the measurement target object. If the value is included in the range of three-dimensional coordinate values indicating the inside of the Fresnel zone, the object to be measured is determined to be an obstacle to wireless communication.

The determination result of the comparison calculation unit 12 is displayed on a monitor in the output unit 13 or output in the form of a paper medium or an electronic file. Note that the Fresnel zone 51 calculated by the Fresnel zone calculation device 3 is displayed three-dimensionally in virtual space on the monitor, and a measurement object such as a tree whose position is specified by the obstacle detection device 2 is superimposed thereon. It is displayed like this.
However, parts of the measurement target that are intruding into the Fresnel zone 51 will be displayed in red to make it clear that they are obstacles to wireless communication, and will be displayed at a certain distance from the Fresnel zone 51. Locations within the range shall be displayed in yellow.

The attitude information acquisition unit 26 includes a 3-axis gyroscope for detecting angles and angular velocities in 3-axis directions (X-axis, Y-axis, Z-axis) and accelerations in 3-axis directions regarding the unmanned aerial vehicle 6. A 3-axis acceleration sensor to detect the azimuth angle based on the detected value in the axial direction, an altimeter sensor to detect the flight altitude, and a horizontal flight speed. Equipped with a horizontal speed sensor for

The obstacle detection system 1 having such a structure has the effect of irradiating the laser light in a desired direction by adjusting the direction of the laser light emitted from the laser range finder 19 using the holder 20. Therefore, by using the obstacle detection system 1, it is possible to easily implement the Fresnel zone inspection method according to the present invention, which is characterized in that the laser beam is divided into two stages and irradiated in two different directions. can.
In the obstacle detection system 1, instead of flying the unmanned flying vehicle 6 with the laser ranging device 19 tilted by the holder 20, the unmanned flying vehicle 6 itself is tilted using the flying vehicle control unit 22. It can be flown. In this case as well, the same functions and effects as in the case where the unmanned flying object 6 is flown with the laser distance measuring device 19 tilted by the holder 20 are exhibited.

A method of inspecting a Fresnel zone formed in a wireless communication zone using the obstacle detection system 1 will be described with reference to FIGS. 3 to 6.
FIG. 3 is a flowchart showing an example of the procedure of the Fresnel zone inspection method according to the present invention, and FIGS. FIG. 2 is a diagram schematically showing a state in which an aircraft is flying.
In addition, FIGS. 5 and 6 show that the Fresnel zone shown in FIG. 7 is the first vertical plane passing through the central axis (the straight line including the line segment P ₁ P ₂ ) at the current position of the unmanned aerial vehicle shown in FIG. It is a figure which schematically showed the state cut by the 2nd vertical plane orthogonal to.
In addition, in FIGS. 4 to 6, the outline of the Fresnel zone is shown by a broken line. Furthermore, the constituent elements already explained using FIGS. 1 and 2 are given the same reference numerals, and the explanation thereof will be omitted as appropriate.

First, the Fresnel zone arithmetic device 3 of the obstacle detection system 1 inputs information such as the positions of the base station 52 and the fixed station 53 and the sizes of the antennas 52a and 53a, which are inputted from the input section 9 and stored in the storage section 10 in advance. The three-dimensional coordinate values of the Fresnel zone 51 are calculated using the information and data such as the frequency of the radio waves used in the above equation (1), and are stored in the storage unit 10 (step S1 in FIG. 3).

The control device 5 reads out the three-dimensional coordinate values of the Fresnel zone 51 stored in the storage unit 10 of the Fresnel zone calculation device 3, and sets the flight path of the unmanned aerial vehicle 6 (step S2 in FIG. 3). Specifically, in the Fresnel zone 51 shown in FIG. 7, among the ellipses that form an outline when cut by a plane passing through the central axis (the straight line including the line segment P ₁ P ₂ ), an ellipse that passes through the central axis A curve P ₁ P ₂ that is perpendicular to the first vertical plane and located below the plane passing through the central axis is defined as the flight path of the unmanned flying object 6. The control device 5 transmits this flight path to the communication section 7 of the obstacle detection device 2, and the communication section 7 stores the flight path received from the control device 5 in the flight object storage section 23 of the unmanned flying object 6.

When the control device 5 transmits a flight start signal to the communication section 7 of the obstacle detection device 2 with the unmanned flying object 6 installed near the antenna 52a of the base station 52 or the antenna 53a of the fixed station 53, the communication section 7 transmits a flight start signal to the flying object control unit 22 of the unmanned flying object 6. The motor 15 receives the flight start signal via the aircraft control unit 22 and starts rotating the propeller 17. At this time, the flying object control section 22 controls the power mechanism and steering mechanism of the unmanned flying object 6 based on the flight path and flight attitude stored in the flying object storage section 23 in advance. Thereby, the unmanned flying object 6 starts flying along a predetermined flight path while maintaining a predetermined flight attitude (step S3 in FIG. 3).

As shown by the arrow in FIG. 4(a), the unmanned flying object 6 irradiates laser light forward in the traveling direction using the laser distance measuring device 19 (step S4 in FIG. 3). Specifically, by adjusting the direction of the laser beam irradiated from the laser range finder 19 by the holder 20, it is tangential to the current position of the curve 29a that forms the outline of the Fresnel zone 51 set on the flight path. A laser beam is irradiated forward along the line.
If there is a measurement target 27a such as a tree in front of the unmanned aerial vehicle 6, the laser distance measuring device 19 measures the distance from the unmanned aerial vehicle 6 to the measurement target 27a, and acquires the measurement result and position information. Based on the current position information of the unmanned flying vehicle 6 acquired by the unit 25, the calculation unit 8 of the obstacle detection device 2 calculates the three-dimensional coordinate values of the measurement target object 27a.

According to the instructions from the control device 5, the Fresnel zone calculation device 3 calculates a point on the boundary surface of the Fresnel zone 51 having the X and Y coordinates of the object to be measured 27a (the point shown in FIG. 4(a) or FIG. 4(b)). _Q2 ) and sends its three-dimensional coordinate values to the control device 5. Thereafter, the laser distance measuring device 19 irradiates a laser beam toward the point _Q2 as shown by the arrow in FIG. 4(b). Note that the point Q ₂ corresponds to the intersection of the boundary surface of the Fresnel zone 51 and the vertical line 28 a passing through the point Q ₁ where the first laser beam is irradiated onto the measurement object 27 a.

When the object to be measured 27a is detected by this second laser beam irradiation, the laser distance measuring device 19 measures the distance from the unmanned flying vehicle 6 to the object to be measured 27a, and as described above, the obstacle detection device 2 The calculation section 8 calculates the three-dimensional coordinate values of the measurement object 27a, and sends the three-dimensional coordinate values to the comparison calculation section 12 of the obstacle determination device 4 via the communication section 7 and the control device 5.

As shown by the arrow in FIG. 5, the unmanned flying object 6 irradiates laser light laterally (in a direction perpendicular to the direction of travel) using the laser distance measuring device 19 (step S5 in FIG. 3). Specifically, by adjusting the direction of the laser beam irradiated from the laser distance measuring device 19 by the holder 20, the Fresnel zone 51 is cut on a second vertical plane orthogonal to a first vertical plane passing through the central axis. The laser beam is emitted in the tangential direction (in both directions) at the current position of the curve 29b, which is perpendicular to the first vertical plane and located below the plane passing through the central axis, of the ellipse that forms the outline when irradiate.
If there is a measurement target 27b such as a tree on the side of the unmanned aerial vehicle 6, the laser distance measuring device 19 measures the distance from the unmanned aerial vehicle 6 to the measurement target 27b, and uses this measurement result and position information. Based on the current position information of the unmanned flying vehicle 6 acquired by the acquisition unit 25, the calculation unit 8 of the obstacle detection device 2 calculates the three-dimensional coordinate values of the measurement target object 27b.

According to the instructions from the control device 5, the Fresnel zone calculation device 3 finds a point (point Q ₄ shown in FIG. 5 or 6) having the X and Y coordinates of the measurement object 27b on the boundary surface of the Fresnel zone 51, The three-dimensional coordinate values are sent to the control device 5. Thereafter, the laser distance measuring device 19 irradiates a laser beam toward the point _Q4 as shown by the arrow in FIG. Note that the point _Q4 corresponds to the intersection of the boundary surface of the Fresnel zone 51 and the vertical line 28b passing through the point _Q3 where the first laser beam is irradiated onto the measurement object 27b.

If the object to be measured 27b is detected on the side of the unmanned aerial vehicle 6 by this second laser beam irradiation, the laser range finder 19 measures the distance from the unmanned aerial vehicle 6 to the object to be measured 27b, and As shown in FIG. Send to Department 12.

The comparison calculation unit 12 compares the three-dimensional coordinate values of the measurement objects 27a and 27b detected by the second laser beam irradiation in step S4 and step S5 shown in FIG. 3 with the three-dimensional coordinate value of the Fresnel zone 51.
As shown in FIGS. 4 to 6, points Q ₂ and Q ₄ are points on the boundary surface of the Fresnel zone 51, so when the measurement objects 27a and 27b are detected at points Q ₂ and Q ₄ , , it is clear that a portion of the measurement objects 27a, 27b exists inside the Fresnel zone 51. In this case, since the three-dimensional coordinate values of the measurement objects 27a and 27b are included in the range of three-dimensional coordinate values indicating the inside of the Fresnel zone 51, the comparison calculation unit 12 It is determined that the object is an obstacle existing inside the Fresnel zone 51 (step S6). On the other hand, in _step S4 _or step _{S5 shown} in FIG. sends the result that there is no possibility that the three-dimensional coordinate values of the measurement objects 27a and 27b are included in the three-dimensional coordinate value range indicating the inside of the Fresnel zone 51 to the control device 5, and the control device 5 sends the result. The comparison calculation unit 12 of the obstacle determination device 4 that has received the determination determines that part of the measurement objects 27a and 27b cannot be an obstacle existing inside the Fresnel zone 51.

As explained above, the Fresnel zone inspection method of the present invention involves flying the unmanned flying object 6 along a predetermined flight path (curve 29a shown in FIG. 4(a) or FIG. 4(b)). However, it is characterized in that the laser beam is divided into two stages and irradiated in two different directions. Then, by the first laser beam irradiation, trees, etc. existing in the vicinity of the lower boundary surface of the Fresnel zone 51 are detected, and by the second laser beam irradiation, the trees, etc. grow upward and It is detected whether or not a portion has invaded the Fresnel zone 51.
As described above, according to the Fresnel zone inspection method of the present invention, some of the trees and the like existing near the lower boundary surface of the Fresnel zone 51 enter the inside of the Fresnel zone 51 and become obstacles. It is possible to clearly distinguish and detect whether or not this is the case.

The Fresnel zone inspection method of the present invention and the obstacle detection system used therein detect objects that can become obstacles to wireless communication inside a Fresnel zone formed between a pair of wireless communication antennas arranged opposite to each other. It is applicable when checking whether or not exists.

DESCRIPTION OF SYMBOLS 1...Obstacle detection system 2...Obstacle detection device 3...Fresnel zone calculation device 4...Obstacle determination device 5...Control device 6...Unmanned flying vehicle 7...Communication section 8...Calculation section 9...Input section 10...Storage section 11 ... Fresnel zone calculation section 12 ... Comparison calculation section 13 ... Output section 14 ... Aircraft input section 15 ... Motor 16 ... Arm 17 ... Propeller 18 ... Body frame 19 ... Laser ranging device 20 ... Holder 21 ... Leg section 22 ... Aircraft Control unit 23...Flight storage unit 24...Flight communication unit 25...Position information acquisition unit 26...Attitude information acquisition unit 27a, 27b...Measurement object 28a, 28b...Plumb line 29a, 29b...Curve 51...Fresnel zone 52... Base station 53... Fixed station 52a, 53a... Antenna 54... Obstacle

Claims (4)

An obstacle detection system used for inspecting a Fresnel zone between a pair of wireless communication antennas arranged oppositely,
an obstacle detection device that acquires position information of a measurement target that can become an obstacle to wireless communication in the Fresnel zone and converts it into three-dimensional coordinate values;
a Fresnel zone calculation device that obtains three-dimensional coordinate values of the Fresnel zone;
an obstacle determination device that determines whether the measurement object corresponds to the obstacle by comparing the three-dimensional coordinate values of the measurement object and the Fresnel zone;
a control device that controls operations of the obstacle detection device, the Fresnel zone calculation device, and the obstacle determination device;
The obstacle detection device includes an unmanned flying vehicle, a communication section, and a calculation section,
The unmanned aerial vehicle is
a laser distance measuring device that measures the distance to the measurement target using laser light;
a holder that holds the laser distance measuring device so that the direction of irradiation of the laser beam can be changed;
a position information acquisition unit that acquires current position information based on a GNSS signal received from a GNSS satellite;
an aircraft storage unit storing a predetermined flight route;
an aircraft control unit that controls a power mechanism and a steering mechanism to enable flight along the flight path stored in the aircraft storage unit;
The calculation unit calculates three-dimensional coordinate values of the measurement target from the distance to the measurement target measured by the laser distance measuring device and the current position information acquired by the position information acquisition unit,
The obstacle determination device includes:
Receiving the three-dimensional coordinate values of the measurement object via the communication unit and the control device, and a range of the three-dimensional coordinate values in which the three-dimensional coordinate values of the measurement object indicate the inside of the Fresnel zone. An obstacle detection system characterized in that the object to be measured is determined to be the obstacle if the object is included in the object. The unmanned flying vehicle includes an attitude information acquisition unit that obtains current flight attitude information,
The flight object storage unit stores a predetermined flight attitude,
The power mechanism and the steering mechanism of the unmanned aircraft control the aircraft based on the current flight attitude information acquired by the attitude information acquisition unit and the flight attitude stored in the aircraft storage unit. The obstacle detection system according to claim 1, wherein the obstacle detection system is controlled by a controller. A method for inspecting a Fresnel zone formed between a pair of wireless communication antennas arranged oppositely, the method comprising:
calculating the three-dimensional coordinate values of the Fresnel zone;
A step of flying an unmanned flying vehicle equipped with a laser ranging device along a predetermined flight path while being able to change the direction of laser light irradiation;
a step of measuring the distance between the unmanned flying vehicle and a measurement object that can become an obstacle to wireless communication in the Fresnel zone, using the laser range finder;
a step of obtaining current position information of the unmanned aerial vehicle and calculating three-dimensional coordinate values of the measurement target from this position information and the measurement results of the laser ranging device;
The three-dimensional coordinate values of the measuring object and the Fresnel zone are compared, and the three-dimensional coordinate value of the measuring object is included in a range of the three-dimensional coordinate values indicating the inside of the Fresnel zone. a step of determining the measurement target object to be the obstacle if
The unmanned aerial vehicle is
Among the ellipses that form an outline when the Fresnel zone is cut by a plane passing through the central axis, the area is perpendicular to the first vertical plane passing through the central axis and below the plane passing through the central axis. The curve in which it is located is the flight path, and
After irradiating the laser beam in the tangential direction of the curve at the current position,
A method for inspecting a Fresnel zone, comprising irradiating the laser beam again toward an intersection between a first vertical line passing through a point where the object to be measured is irradiated with the laser beam and a boundary surface of the Fresnel zone. . The unmanned aerial vehicle is
Among the ellipses that form an outline when the Fresnel zone is cut at the current position by a second vertical plane perpendicular to the first vertical plane, the ellipse is perpendicular to the first vertical plane and After irradiating the laser beam in a tangential direction at the current position of the curve located below a plane passing through the central axis,
4. The laser beam is irradiated again toward the intersection of the boundary surface of the Fresnel zone and a second vertical line passing through the point where the laser beam was irradiated onto the measurement object. Fresnel zone inspection method.

Images