JP2024140402A - Method using optical remote airflow measurement device and wind condition observation system - Google Patents

Abstract

[Problem] The objective is to perform wind observation with little optical axis error. [Solution] A first step is to fly an artificial flying object (1), a second step is to direct a laser beam emitted from an optical remote air current measurement device (2) at the artificial flying object (1), and a third step is to detect the light reflected by the artificial flying object (1) with the optical remote air current measurement device (2). [Selected Figure] Figure 1

Description

Application for application of Article 30, Paragraph 2 of the Patent Act filed. (1) Presented at the Grand Renewable Energy 2022 International Conference on December 19, 2022. (2) Presented in the Proceedings of the Japan Wind Energy Society, Vol. 46, No. 4 (Issue No. 144), February 2023, published by the Japan Wind Energy Society, on March 22, 2023.

The present invention relates to a method for optical axis correction and observation using an optical remote airflow measurement device, such as a Doppler LIDAR, and a wind condition observation system.

Patent Document 1 and Non-Patent Document 1 describe optical remote airflow measurement devices, such as Doppler LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging).

JP 2021-187258 A

"Japan Meteorological Corporation Homepage: Doppler Lidar (https://n-kishou.com/corp/service/observation/streamline/product.html)"

An optical remote airflow measurement device, typified by the Doppler LIDAR, is a type of remote airflow measurement device that can measure the relative movement speed of an object by observing the wavelength shift caused by the Doppler effect of scattered light that occurs when a laser beam is irradiated onto aerosols in the atmosphere. Optical remote airflow measurement devices are composed of relatively heavy and large components, so errors in the optical axis are prone to occur. The present invention aims to perform more accurate wind observations by correcting the optical axis error caused by optical remote airflow measurement devices.

The method for solving the above problem is as follows:
[1] This method comprises a first step of flying an artificial aircraft 1, a second step of directing a laser beam emitted from an optical remote airflow measurement device 2 at the artificial aircraft 1, and a third step of detecting the light reflected by the artificial aircraft 1 with the optical remote airflow measurement device 2.

[2] In the above method, it is preferable to further include a fourth step of placing the artificial aircraft 1 within the field of view 4 of the theodolite 3.

[3] In each of the above methods, it is preferable to further include a fifth step of acquiring the difference between the elevation angle θGD of the artificial aircraft 1 detected by the optical remote airflow measurement device 2 and the elevation angle θGT of the artificial aircraft 1 that is within the field of view 4 of the theodolite 3 (hereinafter, the "elevation angle difference").

[4] In each of the above methods, it is preferable to further include a sixth step of acquiring the difference between the azimuth angle θHD of the artificial aircraft 1 detected by the optical remote airflow measurement device 2 and the azimuth angle θHT of the artificial aircraft 1 that is within the field of view 4 of the theodolite 3 (hereinafter, the "azimuth angle difference amount").

[5] In each of the above methods, it is preferable to further include a seventh step of acquiring wind conditions at a position shifted by an amount equivalent to the elevation angle difference and/or the azimuth angle difference from the captured position of the artificial aircraft 1 in a two-dimensional image having an azimuth axis and an elevation axis obtained from the optical remote airflow measurement device 2.

[6] In each of the above methods, a 71st step of acquiring a first wind condition at a first observation point P1 where an optical remote airflow measurement device 2 is installed using the method described in [5] above;
It is preferable to further include a step (72) of acquiring second wind conditions at the second observation point P2 where the optical remote airflow measurement device 2 is installed, using the method described in [5] above.

[7] The system that solves the above problem is a wind observation system that includes an optical remote airflow measurement device 2, an altazimuth mount 3, and an artificial flying object 1 captured in a two-dimensional image having an azimuth axis and an elevation axis obtained from the optical remote airflow measurement device 2, the optical remote airflow measurement device 2 includes a first fixed part 21 and a first rotating part 22 that is fixed to be rotatable in the azimuth direction and/or elevation direction relative to the first fixed part 21, the first rotating part 22 includes a laser light emitting part 27 and a light detecting part 28, the altazimuth mount 3 includes a second fixed part 31 and a second rotating part 32 that is fixed to be rotatable in the azimuth direction and/or elevation direction relative to the second fixed part 31, the second rotating part 32 includes a telephoto lens system that captures the artificial flying object 1 within its field of view, and the first fixed part 21 and the second fixed part 31 are directly or indirectly fixed to each other.

The reference symbols [1] to [7] are added for convenience and do not limit the invention.

The present invention provides a method and system for more accurate wind observation by comprising a first step of flying an artificial flying object, a second step of directing laser light emitted from an optical remote airflow measurement device at the artificial flying object, and a third step of detecting the light reflected by the artificial flying object with the optical remote airflow measurement device.

1 is a diagram showing an example of a wind condition observation system used in a method according to a first embodiment of the present invention; FIG. 1 is a diagram showing an artificial flying object, an optical remote airflow measurement device, and a theodolite that constitute a wind condition observation system for use in a method according to a first embodiment of the present invention. 2 shows the field of view of the theodolite shown in FIG. 1 . 2 is a two-dimensional image having an azimuth axis and an elevation axis obtained from the optical remote airflow measurement device shown in FIG. 1. 1 is a graph showing the difference between the elevation angle of the artificial aircraft body relative to the azimuth angle observed by the theodolite shown in FIG. 1 and the elevation angle of the artificial aircraft body observed by an optical remote airflow measurement device, while the horizontal axis shows the azimuth angle and the vertical axis shows the difference between the elevation angle of the artificial aircraft body relative to the azimuth angle observed by the theodolite shown in FIG. 3 is a diagram showing an example of a wind condition observation form using the wind condition observation system shown in FIG. 2. FIG. 11 is a diagram showing a wind condition observation system according to a second embodiment of the present invention.

The present invention will be described in more detail below based on the following embodiment, but the present invention is not limited to the following embodiment, and it is of course possible to implement the invention with modifications within the scope of the above and below described aims, and all such modifications are included in the technical scope of the present invention.

(Embodiment 1)
FIG. 1 shows an example of a wind condition observation system used in the method according to the first embodiment of the present invention. As shown in FIG. 1, the wind condition observation system (elements other than the artificial aircraft) is composed of an optical remote airflow measurement device 2 and a theodolite 3. The optical remote airflow measurement device 2 is a remote airflow measurement device that can observe the relative moving speed and displacement of an observation target by observing the wavelength shift due to the Doppler effect of scattered light generated when a laser light is irradiated to aerosols contained in the atmosphere. As the optical remote airflow measurement device 2, for example, Stream Line XR manufactured by Lumibird or WindCube Scan 400S manufactured by Vaisala can be used. The optical remote airflow measurement device 2 is provided with a laser light emission unit 27 and a light detection unit 28 that detects light scattered or reflected by the observation target. FIG. 1 illustrates an example in which the laser light emitting unit 27 and the light detecting unit 28 are arranged coaxially, but there are no particular limitations on the arrangement of the laser light emitting unit 27 and the light detecting unit 28, and they may be arranged anywhere in the optical remote airflow measuring device 2.

The altazimuth 3 has a telephoto lens system and is a surveying instrument that measures angles relative to a collimated point or direction based on the optical axis of the telephoto lens system; it is also known as a "transit" or "theodolite." Normally, the altazimuth 3 is mounted on a dedicated tripod during surveying. In the first embodiment of the present invention, it is preferable to mount the altazimuth 3 on a part of the optical remote airflow measurement device 2 (for example, on the housing 25 as shown in Figure 1) without using a tripod.

Figure 2 is a diagram showing the artificial air vehicle 1, the optical remote airflow measurement device 2, and the altazimuth mount 3 that constitute the wind condition observation system used in the method according to the first embodiment of the present invention. As shown in Figure 2, the optical remote airflow measurement device 2 and the altazimuth mount 3 are directed toward the artificial air vehicle 1. The artificial air vehicle 1 may be a helicopter with a person on board, or an unmanned aircraft without a person on board, such as a drone, may also be used.

Figure 3 shows the field of view 4 of the theodolite 3, with the artificial aircraft 1 included within the field of view 4.

Figure 4 shows a two-dimensional image with azimuth and elevation axes obtained from the light output from the laser light emitting unit 27 of the optical remote airflow measurement device 2 and returning from the object being observed.

A method according to the first embodiment of the present invention will be described below.
<First step>
This is a step of flying the artificial aircraft 1 in a target airspace for wind condition observation. It is preferable that the artificial aircraft 1 is hovered at a specific point that is the observation target.

<Second step>
This is a step of irradiating the artificial air vehicle 1 with the laser light emitted from the optical remote airflow measurement device 2. The laser light may be irradiated to the entire artificial air vehicle 1 or to a part of the artificial air vehicle 1. The laser light may be irradiated continuously or in a pulsed manner.

<Third step>
This is a step in which the light 4 reflected by the artificial air vehicle 1 is detected by the optical remote airflow measurement device 2. The detection result may be, for example, a two-dimensional image having an azimuth axis and an elevation axis, such as a light intensity distribution map or a carrier-to-noise ratio distribution map (CNR).

Conventionally, various methods have been used to use the optical remote airflow measurement device 2, but there is no technology to direct the laser light 3 emitted from the optical remote airflow measurement device 2 at the artificial air vehicle 1, and of course there is no technology to detect the light 4 (reflected light of the laser light 3) reflected by the artificial air vehicle 1 with the optical remote airflow measurement device 2. In the method according to the first embodiment of the present invention, it is expected that new information derived from the artificial air vehicle 1 obtained from the optical remote airflow measurement device 2 will be used to improve the positional accuracy of wind condition observation. Below, a more preferable additional step of wind condition observation will be described.

<Fourth step>
This is a step of placing the artificial aircraft 1 within the field of view 4 of the theodolite 3. It is sufficient that at least a part of the artificial aircraft 1 is within the field of view 4 of the theodolite 3. As shown in Fig. 3, the center of the artificial aircraft 1 may be set to the center of the field of view 4 of the theodolite 3, or a specific part of the artificial aircraft 1 (for example, the end of the right arm) may be set to the center of the field of view 4 of the theodolite 3.

Execution of the fourth step is one example of the use of the information detected by the optical remote air current measurement device 2 in the third step, which makes it possible to identify the relative relationship between the artificial aircraft 1, the optical remote air current measurement device 2, and the theodolite 3, and provides accurate wind observation. It is preferable that the difference in height between the installation position of the light detection unit 28 of the optical remote air current measurement device 2 and the installation position of the telephoto lens system of the theodolite 3 is small, and the difference in height is preferably within 100 cm, more preferably within 60 cm, and even more preferably within 30 cm.

<5th step>
It is preferable to include a step of acquiring the difference between the elevation angle θGD of the artificial aircraft 1 detected by the optical remote airflow measurement device 2 and the elevation angle θGT of the artificial aircraft 1 that is within the field of view 4 of the theodolite 3 (hereinafter referred to as the "elevation angle difference"). Since the purpose of the fifth step is to acquire the elevation angle difference, it is not necessary to acquire absolute values of the elevation angles θGD and θGT, and the difference may be determined by a relative value from a reference direction. Since the direction specified by the theodolite 3 can be treated as a true value, the fifth step makes it possible to grasp the degree to which the elevation angle θGD of the artificial aircraft 1 detected by the optical remote airflow measurement device 2 deviates from the true value θGT.

Figure 5 is a graph showing the difference between the elevation angle θGT of the artificial aircraft 1 observed by the theodolite 3 and the elevation angle θGD of the artificial aircraft 1 observed by the optical remote airflow measurement device 2, with the horizontal axis showing the azimuth angle and the vertical axis showing the elevation angle difference. Note that in Figure 5, the ■ mark indicates the position of the artificial aircraft 1, and the ● mark indicates the position of the reference mast at a different azimuth angle from the artificial aircraft 1.

<Sixth step>
It is preferable to include a step of acquiring a difference (hereinafter, "azimuth angle difference") between the azimuth angle θHD (not shown) of the artificial aircraft 1 detected by the optical remote airflow measurement device 2 and the azimuth angle θHT (not shown) of the artificial aircraft 1 that is within the field of view 4 of the theodolite 3. Since the gist of the sixth step is to acquire the azimuth angle difference, it is not necessarily necessary to acquire absolute values of the azimuth θHD and the azimuth angle θHT, and the difference may be determined by a relative value from a reference direction. Since the azimuth specified by the theodolite 3 can be treated as a true value, this sixth step makes it possible to grasp the degree to which the azimuth angle θHD of the artificial aircraft 1 detected by the optical remote airflow measurement device 2 deviates from the true value θHT.

<Seventh step>
This is a step of acquiring wind conditions at a position shifted by an amount equivalent to the elevation angle difference and/or azimuth angle difference from the captured position of the artificial aircraft 1 in a two-dimensional image having an azimuth axis and an elevation axis obtained from the optical remote airflow measurement device 2.

Figure 4 is a two-dimensional image having an azimuth axis and an elevation axis obtained from the optical remote airflow measurement device 2, and shows a carrier-to-noise ratio distribution map (CNR) here. Three consecutive dark pixels in the horizontal axis direction can be seen near the center of Figure 4, which is an image of the artificial aircraft 1. In Figure 4, the point at 239.610° on the horizontal axis and 2.920° on the vertical axis corresponds to the right end of the artificial aircraft 1 as seen from the optical remote airflow measurement device 2 side, but this point contains an error equivalent to the difference amount shown in Figure 5 above. Therefore, the true elevation angle and true azimuth angle can be identified by acquiring the wind conditions at a position shifted by an amount equivalent to the elevation angle difference amount and/or azimuth angle difference amount from the position of the artificial aircraft 1 in the carrier-to-noise ratio distribution map (CNR). More specifically, the ■ mark indicating the position of the artificial aircraft 1 in Figure 5 has an error of approximately minus 0.15 degrees in the elevation angle direction, so the carrier-to-noise ratio distribution map (CNR) needs to be corrected by approximately plus 0.15 degrees in the elevation angle direction.

<Step 71 and Step 72>
By executing the seventh step, it is possible to obtain an azimuth angle and/or an elevation angle with the error corrected, but since the wind condition observation value based on one observation point is a one-dimensional velocity component in the direction of the laser light irradiation of the optical remote airflow measurement device 2, only the velocity component of the aerosol being observed moving away or approaching can be obtained. Therefore, by executing the seventh step at multiple observation points, it is possible to calculate the wind conditions at the observation point as a vector.

Figure 6 is a diagram showing an example of the observation form of the wind condition observation system. As shown in Figure 6, the wind condition observation system in the first embodiment of the present invention is installed at a first observation point P1 and a second observation point P2, which are different on land along the coastline. The observation method includes performing the seventh step at the first observation point P1 where the optical remote airflow measurement device 2 is installed, i.e., step 71 of acquiring the first wind conditions, and performing the seventh step at the second observation point P2 where the optical remote airflow measurement device 2 is installed, i.e., step 72 of acquiring the second wind conditions, thereby making it possible to acquire the wind conditions as vectors. One or both of the first observation point P1 and the second observation point P2 may be located on the sea.

(Embodiment 2)
FIG. 7 shows an example of a wind observation system for use in a method according to a second embodiment of the present invention, but the artificial aircraft 1 is not shown. Other configurations or symbols that overlap with those of the first embodiment will not be described. As shown in FIG. 7, the optical remote airflow measurement device 2 has a first fixed part 21 and a first rotating part 22 that is fixed to be rotatable in the azimuth direction and/or elevation angle direction relative to the first fixed part 21, and the first rotating part 22 is provided with a laser light emitting part 27 and a light detecting part 28. The theodolite 3 has a second fixed part 31 and a second rotating part 32 that is fixed to be rotatable in the azimuth direction and/or elevation angle direction relative to the second fixed part 31, and the second rotating part 32 is provided with a telephoto lens system that captures the artificial aircraft 1 within its field of view. The first fixed part 21 and the second fixed part 31 are in a fixed relationship with each other. With this configuration, it is possible to correct errors in the azimuth direction and/or elevation angle direction of the optical remote airflow measurement device 2 based on the theodolite 3. FIG. 7 shows an example in which the second fixed portion 31 is directly fixed to the first fixed portion 21, but the same implementation is also possible in which the second fixed portion 31 is indirectly fixed to the first fixed portion 21 via something else, such as the housing 25 shown in FIG. 1.

REFERENCE SIGNS LIST 1 Artificial flying object 2 Optical remote airflow measurement device 21 First fixed part 22 First rotating part 25 Housing 27 Laser light emitting part 28 Light detection part 3 Theodolite 31 Second fixed part 32 Second rotating part 4 Field of view θGD Elevation angle of the artificial flying object detected by the optical remote airflow measurement device θGT Elevation angle of the artificial flying object that has entered the field of view of the theodolite θHD Azimuth angle of the artificial flying object detected by the optical remote airflow measurement device θHT Azimuth angle of the artificial flying object that has entered the field of view of the theodolite P1 First observation point P2 Second observation point

Claims (7)

A first step of flying the artificial air vehicle;
A second step of directing a laser beam emitted from an optical remote airflow measurement device onto the artificial flying object;
a third step of detecting light reflected by the artificial air vehicle with the optical remote airflow measurement device;
The method according to claim 1, The method of claim 1, further comprising a fourth step of placing the artificial air vehicle within the field of view of the theodolite. The method according to claim 2, further comprising a fifth step of acquiring the difference between the elevation angle of the artificial flying object detected by the optical remote airflow measurement device and the elevation angle of the artificial flying object that is within the field of view of the theodolite (hereinafter referred to as the "elevation angle difference"). The method according to claim 2, further comprising a sixth step of acquiring the difference between the azimuth angle of the artificial flying object detected by the optical remote airflow measurement device and the azimuth angle of the artificial flying object that is within the field of view of the theodolite (hereinafter, the "azimuth angle difference"). The method according to claim 3, further comprising a seventh step of acquiring wind conditions at a position shifted by an amount equivalent to the elevation angle difference and/or the azimuth angle difference from the captured position of the artificial flying object in a two-dimensional image having an azimuth axis and an elevation angle axis obtained from the optical remote airflow measurement device. A 71st step of acquiring a first wind condition using the method according to claim 5 at a first observation point where an optical remote airflow measurement device is installed;
(72) acquiring second wind conditions using the method of claim 5 at a second observation point where an optical remote airflow measurement device is installed. A wind condition observation system comprising an optical remote airflow measurement device, a theodolite, and an artificial flying object captured in a two-dimensional image having an azimuth axis and an elevation axis obtained from the optical remote airflow measurement device,
the optical remote airflow measurement device has a first fixed part and a first rotating part fixed to be rotatable in an azimuth angle direction and/or an elevation angle direction with respect to the first fixed part, the first rotating part being provided with a laser light emitting part and a light detecting part;
the theodolite has a second fixed part and a second rotating part fixed to be rotatable in an azimuth angle direction and/or an elevation angle direction with respect to the second fixed part, and the second rotating part is provided with a telephoto lens system that captures the artificial aircraft within a field of view;
A wind condition observation system in which the first fixed part and the second fixed part are directly or indirectly in a fixed relationship.