Method of flying rotary-wing unmanned aerial vehicle in strong wind

Abstract

To provide a flight method for stably flying a rotary wing unmanned aircraft even in a strong wind.SOLUTION: A method for flying a rotary-wing unmanned aerial vehicle, comprising: when a wind speed at a predetermined height is less than or equal to 10m / s, flying at a flight height less than or equal to 0.5 meters to fly at a wind speed less than or equal to 5m / s.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method for flying a rotary-wing unmanned aerial vehicle in strong winds. [Background technology]

[0002] Rotary-wing unmanned aerial vehicles (ROVs), such as drones, are used in a variety of applications, including photography and delivery. Conventionally, flight stability in strong winds can be an issue for such ROVs. Several research studies have addressed this issue, all of which involve tests simulating strong winds. Such tests have only reported on the behavior of ROVs in strong winds, and for small ROVs in particular, it is practically difficult to install new control devices or large motors due to their mechanical limitations, making it difficult to ensure flight stability in strong winds.

[0003] In response to this, the Ministry of Land, Infrastructure, Transport and Tourism's Civil Aviation Bureau Standard Manual 2 states, under 3. Necessary measures to ensure safety, 3-1, "Basic measures when flying an unmanned aircraft (2) Do not fly in wind speeds of 5 m / s or more." This means that even if a rotary-wing unmanned aircraft has the wind resistance capability to withstand a maximum wind pressure resistance of 10 m / s, the flight will be suspended.

[0004] Furthermore, Japanese Patent Application Laid-Open Publication No. 2022-087355 discloses a "drone system including at least multiple drones that fly within a work area to perform work and a control device that controls the operation of the multiple drones, the drone system including a mobile control unit that flies some or all of the multiple drones at a predetermined distance from the mobile body when the mobile body and the multiple drones are moving." In this system, too, in the event of an abnormality, including various events such as strong winds, extremely low or high temperatures, getting caught on an obstacle, or a bird strike, the malfunctioning drone is commanded to return and land immediately. [Prior art documents] [Non-patent literature]

[0005] Ministry of Land, Infrastructure, Transport and Tourism Civil Aviation Bureau Standards Manual 2 https: / / www.mlit.go.jp / common / 001218180.pdf [Patent documents]

[0006] Japanese Patent Publication No. 2022-087355 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0007] The present invention has been made in light of the above points, and its object is to provide a flight method for flying a rotary-wing unmanned aerial vehicle stably even in strong winds.

[0008] Therefore, the inventor measured the distribution of wind speeds during strong winds and discovered how the drone would fly depending on the measurements.

[0009] In order to solve the above problem, the first aspect of the method for flying a rotary-wing unmanned aircraft is to fly at an altitude of 0.5 meters or less when the wind speed at a specified altitude is 10 m / s or less, in order to fly at a wind speed of 5 m / s or less.

[0010] In order to solve the above problem, the second aspect of the method for flying a rotary-wing unmanned aircraft is to fly at an altitude of 0.5 meters or less when the wind speed at a specified altitude over a river is 10 m / s or less, in order to fly at a wind speed of 5 m / s or less.

[0011] In order to solve the above problem, a third aspect of the present invention is a flight method for a rotary-wing unmanned aerial vehicle according to the first or second aspect, wherein the predetermined altitude is 10 meters. [Effects of the Invention]

[0012] The present invention is configured and operates as described above, and therefore can provide a flight method for stably flying a rotary-wing unmanned aerial vehicle even in strong winds. [Brief explanation of the drawings]

[0013] [Figure 1] A is a graph showing the distribution of altitude and wind speed. B is a graph showing the altitude of A on a logarithmic scale. C is a display of Equation 1. [Figure 2] This is a graph showing the occurrence rate of wind speed. [Figure 3] This is an illustration of the verification process through wind tunnel testing. [Figure 4] This figure shows the maximum displacement of a rotary-wing unmanned aerial vehicle when the wind tunnel airflow speed is 5 m / s. [Figure 5] A shows flight tests of a rotorcraft unmanned aerial vehicle (UAV) flying at an altitude of 0.5 meters and another at an altitude of 5 meters. B summarizes the results of the flight test in A. BEST MODE FOR CARRYING OUT THE INVENTION

[0014] The flight method of rotary-wing unmanned aerial vehicle 10 will be described below. When the wind speed at a predetermined altitude is 10 m / s or less, rotary-wing unmanned aerial vehicle 10 flies at a flight altitude of 0.5 meters or less in order to fly at a wind speed of 5 m / s or less. Rotary-wing unmanned aerial vehicle 10 is sometimes called a drone. Here, the predetermined altitude may refer to an altitude of 5 to 10 meters. Furthermore, altitude refers to the height above mean sea level or the ground.

[0015] Conventional rotary-wing unmanned aerial vehicles 10 fly, for example, at altitudes of 5 to 10 meters in urban areas, but as mentioned above, in strong winds with wind speeds of 5 m / s or more, the flight is suspended for safety reasons.

[0016] Therefore, the inventors of the present application have recorded wind speeds measured at altitudes of 0.2 meters, 0.4 meters, 0.8 meters, 1.6 meters, 3.2 meters, 6.4 meters, and 12.8 meters, as shown in Figure 1A. Note that no measurements were made below 0.012 meters.

[0017] Here, FIG. 1B shows the altitude in FIG. 1A using a logarithmic scale.

[0018] Therefore, the inventors of the present application discovered that if the line of the vertical distribution measured at an altitude of 0.2 meters or more is extended downward, it is predicted that the wind speed will be 0 m / s at an altitude of 0.012 meters (see Figure 1B).

[0019] On the other hand, if we assume that α is 0.2 in Equation 1 shown in Figure 1C, the wind speed ratio at 10 meters and 0.5 meters above ground is approximately 1 / 2. Note that the equation shown in Figure 1C is a general equation for the velocity component in the height direction, and in this equation shown in Figure 1C, Z1 is the reference height (here, 10 meters), Uatz1 is the wind speed at the reference height, Uatz2 is the wind speed [m / s] at the height to be calculated, Z2 is that height (here, 0.5 meters), and it is known that α is approximately 0.15 to 0.3, and particularly in residential areas, α is approximately 0.2 to 0.25, preferably 0.2.

[0020] Z2 is at an altitude of 0.5 meters, and Z1 is at an altitude of 10 meters. Uatz2 is the wind speed at an altitude of 0.5 meters, and Uatz1 is the wind speed at an altitude of 10 meters.

[0021] As such, it has been shown that wind speed increases exponentially with altitude within the ground boundary layer at 10 to 50 meters above ground level, and the reverse is also true. Therefore, even in a strong wind with a wind speed of 5 m / s or more at 10 meters above ground level, for example, it has been discovered that rotary-wing unmanned aircraft 10 may be able to fly by flying at a low altitude in urban areas, etc., rather than flying at an altitude of 5 to 10 meters.

[0022] On the other hand, data from observation data off the coast of Kitakyushu (https: / / www.nedo.go.jp / fuusha / public / k_1_01.html) is shown in Figure 2. Figure 2 is a graph of the occurrence rate of wind speeds. The horizontal axis is wind speed by class, and the vertical axis is the occurrence rate of wind speed. This means that even if the area surrounded by the dashed line (30) is flyable, the area surrounded by the solid line (40) cannot be flown at wind speeds of this magnitude.

[0023] However, even if the wind speed at an altitude of 10 meters is 5 m / s or more, flying at an altitude of 0.5 meters is expected to keep the wind speed below 5 m / s. If we multiply this frequency by 365 x 24 = 8,760 hours, the dashed area 30 can be (2.1 + 4.4 + 7.5 + 9.3 + 10.5) percent, plus the solid area 40 (10.8 + 10.8 + 10.6 + 8.1 + 6.5) percent can be added to the blue area, which means that it can be flown for a considerable amount of time in a year.

[0024] Therefore, as shown in Figure 3, an experiment was conducted in which rotary-wing unmanned aerial vehicle 10 was plunged into a wind tunnel when the airflow velocity was 5 m / s. The maximum displacement was 345 millimeters. This means that the maximum displacement of rotary-wing unmanned aerial vehicle 10 when the wind tunnel airflow velocity was 5 m / s was limited to 345 millimeters. Therefore, Figure 4 shows that rotary-wing unmanned aerial vehicle 10 is fully capable of flying if the wind velocity is 5 m / s.

[0025] Additionally, outdoor flight experiments were conducted with rotary-wing unmanned aerial vehicle 10A flying at an altitude of 0.5 meters in windy conditions and rotary-wing unmanned aerial vehicle 10B flying at an altitude of 5 meters. In these experiments, the displacements in the X and Y directions on the xy plane of rotary-wing unmanned aerial vehicle 10A and rotary-wing unmanned aerial vehicle 10B flying from origin O were measured (see Figure 5A).

[0026] The table in Figure 5B shows that the displacement in the X direction at an altitude of 0.5 meters is -27.5 mm, the displacement in the Y direction at an altitude of 0.5 meters is -24.1 mm, and the total displacement is 36.5 mm. The displacement in the X direction at an altitude of 5 meters is 75.6 mm, and the displacement in the Y direction at an altitude of 5 meters is -336.8 mm, and the total displacement is 345.2 mm.

[0027] Furthermore, the ratio of the total displacement of rotary-wing unmanned aerial vehicle 10A flying at a flight altitude of 0.5 meters to the total displacement of rotary-wing unmanned aerial vehicle 10B flying at a flight altitude of 5 meters was 9.4. In this way, it was proven that the total displacement of rotary-wing unmanned aerial vehicle 10A flying at a flight altitude of 0.5 meters is significantly lower than the total displacement of rotary-wing unmanned aerial vehicle 10B flying at a flight altitude of 5 meters. In other words, it can be said that the total displacement of rotary-wing unmanned aerial vehicle 10A flying at a flight altitude of 0.5 meters is sufficient for practical use.

[0028] Therefore, we discovered that when the wind speed at a given altitude, for example 10 meters, is 10 m / s or less, the rotary-wing unmanned aircraft 10 can fly stably by setting the flight altitude for flight at a wind speed of 5 m / s or less to 0.5 meters or less.

[0029] However, when transporting in urban areas, there is a risk of collision with obstacles on the ground at altitudes of 0.5 meters or less in urban areas. On the other hand, it is conceivable that future rotorcraft 10 will fly over rivers. In this case, if flight restrictions are relaxed, it may be possible to fly near the river surface. Furthermore, real-time river monitoring during rainfall is required for flood prevention measures, and this technology could contribute to achieving this.

[0030] Therefore, to ensure stable flight of rotary-wing unmanned aerial vehicle 10, it is preferable to fly it over a river. In this case, a flight method for rotary-wing unmanned aerial vehicle 10 has been discovered in which the flight altitude is 0.5 meters or less to fly at a wind speed of 5 m / s or less when the wind speed at a predetermined altitude, for example, an altitude of 5 to 10 meters, is 10 m / s or less. Therefore, a flight method for rotary-wing unmanned aerial vehicle has been discovered in which the flight altitude is 0.5 meters or less to fly at a wind speed of 5 m / s or less when the wind speed at the predetermined altitude is 10 m / s or less, and a flight method for rotary-wing unmanned aerial vehicle has been discovered in which the flight altitude is 0.5 meters or less to fly at a wind speed of 5 m / s or less when the wind speed at a predetermined altitude over a river is 10 m / s or less. These predetermined altitudes are preferably 5 to 10 meters. [Explanation of symbols]

[0031] 10 Rotary-wing Unmanned Aerial Vehicles 10A Rotary-wing unmanned aerial vehicle flying at a flight altitude of 0.5 meters 10B Rotary-wing unmanned aerial vehicle flying at an altitude of 5 meters 30 Area enclosed by dashed lines 40 Area enclosed by solid lines

Claims

1. A flight method for a rotary-wing unmanned aerial vehicle, in which the flight altitude is 0.5 meters or less in order to fly at a wind speed of 5 m / s or less when the wind speed at a predetermined altitude is 10 m / s or less.

2. A flight method for a rotary-wing unmanned aerial vehicle in which the flight altitude is 0.5 meters or less in order to fly at a wind speed of 5 m / s or less when the wind speed at a predetermined altitude over a river is 10 m / s or less.

3. 3. The method for flying a rotary-wing unmanned aerial vehicle according to claim 1, wherein the predetermined altitude is 10 meters.

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