Radar ocean wave analysis device, radar ocean wave analysis program, and radar ocean wave analysis drone

Abstract

To calculate at least one of an ocean wave height, an ocean wave wavelength, an ocean wave direction, and an ocean wave velocity with high accuracy, even when azimuth resolution of radar ocean wave analysis processing is low because a radar is small or a frequency of the radar is low.SOLUTION: A radar ocean wave analysis device 2 performs an ocean wave analysis using a radar. The radar ocean wave analysis device 2 includes: an analysis area direction setting section 23 that sets a depth direction and a width direction of a rectangular analysis area in which the ocean wave analysis is performed to a facing direction, a parallel direction, and a perpendicular direction with respect to an ocean wave direction, respectively; and a radar ocean wave analysis section 21 that performs an ocean wave analysis of at least one of an ocean wave height, an ocean wave wavelength, and an ocean wave velocity on the basis of a radar scan image in the analysis area set by the analysis area direction setting section 23.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a technique for performing ocean wave analysis using radar. [Background technology]

[0002] Techniques for performing wave analysis using radar are disclosed in Patent Documents 1 to 3, etc. In Patent Documents 1 to 3, a rectangular analysis area for performing wave analysis is set, and wave analysis of wave height, wave wavelength, wave direction, and wave speed is performed based on a radar scan image within the analysis area. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-094995 [Patent Document 2] Japanese Patent Application Publication No. 2020-094996 [Patent Document 3] Japanese Patent Application Publication No. 2020-094997 Summary of the Invention [Problem to be solved by the invention]

[0004] The issues with radar wave analysis processing using conventional technology are shown in Figure 1. In Figure 1, an analysis area A of approximately 2000 m x 2000 m is set, and wave analysis is performed based on a radar scan image R within analysis area A. The left and right columns of Figure 1 have different azimuth resolutions for radar wave analysis processing.

[0005] In the left column of Figure 1, a large radar is mounted on a vessel, etc., with a narrow radar beam width and high azimuth resolution for radar wave analysis processing. Alternatively, the radar frequency is high and the azimuth resolution for radar wave analysis processing is high. Therefore, even if the wave crests in the radar scan image R within the analysis area A have a short wave wavelength, adjacent wave crests do not overlap due to the high azimuth resolution, so the wave height, wave wavelength, wave direction, and wave speed can be calculated with high accuracy.

[0006] In the right column of Figure 1, a small radar is mounted on a drone or aircraft, and the radar beam width is wide, resulting in low azimuth resolution for radar wave analysis processing. Alternatively, the radar frequency is low, resulting in low azimuth resolution for radar wave analysis processing. Therefore, in radar scan image R within analysis area A, if the wave crests have short wave wavelengths, adjacent wave crests will overlap due to the low azimuth resolution, making it impossible to calculate the wave height, wave wavelength, wave direction, and wave speed with high accuracy.

[0007] Therefore, in order to solve the above problem, the present disclosure aims to calculate at least one of the wave height, wave wavelength, wave direction, and wave speed with high accuracy even when the azimuth resolution of the radar wave analysis process is low due to the radar being small or the radar frequency being low. [Means for solving the problem]

[0008] In order to solve the above problem, the "depth direction" and "width direction" of the analysis area are set to be "parallel" and "perpendicular" to the direction directly facing the wave direction, respectively.

[0009] Here, let us consider a case where the "depth direction" and "width direction" of the analysis area are set to the direction directly facing the ocean wave direction, and the "perpendicular direction" and "parallel direction," respectively. In this case, when the azimuth resolution of the radar wave analysis process is low, adjacent wave crests with short wave wavelengths are likely to overlap each other in the radar scan image within the analysis area due to the low azimuth resolution.

[0010] On the other hand, consider the case where the "depth direction" and "width direction" of the analysis area are set to the direction directly facing the wave direction, and the "parallel direction" and "perpendicular direction," respectively. In this case, even when the azimuth resolution of the radar wave analysis process is low, adjacent wave crests in the radar scan image within the analysis area are unlikely to overlap, even if the wave crests have a short wave wavelength, regardless of the low azimuth resolution.

[0011] Specifically, the present disclosure is a radar wave analysis device that performs wave analysis using a radar, and is characterized by comprising: an analysis area direction setting unit that sets the depth and width directions of a rectangular analysis area in which wave analysis is performed to be parallel and perpendicular to the facing direction relative to the wave direction of the waves, respectively; and a radar wave analysis unit that performs wave analysis of at least one of wave height, wave wavelength, and wave speed of the waves based on a radar scan image within the analysis area set by the analysis area direction setting unit.

[0012] With this configuration, even when the azimuth resolution of the radar wave analysis process is low because the radar is small or the radar frequency is low, it is possible to calculate at least one of the wave height, wave wavelength, wave direction, and wave speed with high accuracy even for wave crests with short wave wavelengths.

[0013] The present disclosure also provides a radar wave analysis device that further includes a wave direction calculation unit that initially sets an initial analysis area as the analysis area and initially calculates the wave direction of waves based on a radar scan image within the initial analysis area, and the analysis area direction setting unit sets the depth direction and width direction of the analysis area to directions parallel and perpendicular to the facing direction of the wave direction initially calculated by the wave direction calculation unit, respectively.

[0014] With this configuration, even when the azimuth resolution of the radar wave analysis process is low, it is possible to calculate the wave direction with a certain degree of accuracy. After initializing the initial analysis area, the analysis area can be set with high accuracy simply by initially calculating the wave direction.

[0015] The present disclosure also provides a radar wave analysis device, characterized in that the wave direction calculation unit determines whether the facing direction of the wave direction recalculated by the analysis area direction setting unit based on the radar scan image within the analysis area set by the analysis area direction setting unit is parallel to the depth direction of the analysis area set by the analysis area direction setting unit, and when the wave direction calculation unit determines that the facing direction is not parallel to the depth direction, the analysis area direction setting unit sets the depth direction and width direction of the analysis area to be parallel and perpendicular, respectively, to the facing direction of the wave direction recalculated by the wave direction calculation unit.

[0016] According to this configuration, when the azimuth resolution of the radar wave analysis process is low, it may not be possible to calculate the wave direction with a certain degree of accuracy. However, by recalculating the wave direction and then re-setting the analysis area, the analysis area can be set with high accuracy.

[0017] The present disclosure also provides a radar wave analysis program for causing a computer to execute the processing steps performed by the processing units included in the above-described radar wave analysis device.

[0018] According to this configuration, it is possible to provide a program having the above-described effects.

[0019] The present disclosure also provides a radar wave analysis drone that is characterized by comprising the above-described radar wave analysis device and a radar transmitter / receiver device for performing wave analysis.

[0020] With this configuration, a drone having the effects described above can be provided. [Effects of the Invention]

[0021] In this way, the present disclosure can calculate at least one of the wave height, wave wavelength, wave direction, and wave speed with high accuracy even when the azimuth resolution of the radar wave analysis process is low due to the radar being small or the radar frequency being low. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram illustrating a problem with radar wave analysis processing in the prior art. [Figure 2] FIG. 1 is a diagram illustrating the principle of radar wave analysis processing according to the present disclosure. [Figure 3] 1 is a diagram illustrating a configuration of a radar ocean wave analysis system according to the present disclosure. [Figure 4] FIG. 2 is a diagram showing a procedure of radar wave analysis processing according to the present disclosure. [Figure 5] FIG. 10 is a diagram showing a specific example of radar wave analysis processing according to the present disclosure. [Figure 6] FIG. 10 is a diagram showing a specific example of radar wave analysis processing according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0023]

[0023] The following embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of implementation of the present disclosure, and the present disclosure is not limited to the following embodiments.

[0024] (Principle of radar wave analysis processing disclosed herein) The principle of the radar wave analysis processing of the present disclosure is shown in Figure 2. In Figure 2, wave analysis is performed based on a radar scan image R (see Figure 1) within an analysis area A. The azimuth resolution of the radar wave analysis processing differs between the left and right columns of Figure 2. The directional relationship between the depth direction of the analysis area A and the direction directly facing the ocean wave direction differs between the upper and lower sections of Figure 2.

[0025] In the lower part of Figure 2, we consider the case where the "depth direction" and "width direction" of analysis area A are set to the direction directly facing the wave direction, and the "perpendicular direction" and "parallel direction," respectively. Then, as shown in the lower left column of Figure 2, when the azimuth resolution of the radar wave analysis process is high, adjacent wave crests W in the radar scan image R within analysis area A are unlikely to overlap due to the high azimuth resolution, even if the wave crests W have a short wave wavelength. On the other hand, as shown in the lower right column of Figure 2, when the azimuth resolution of the radar wave analysis process is low, adjacent wave crests W in the radar scan image R within analysis area A are likely to overlap due to the low azimuth resolution, if the wave crests W have a short wave wavelength.

[0026] In the upper part of Figure 2, we consider the case where the "depth direction" and "width direction" of analysis area A are set to the direction directly facing the wave direction, and the "parallel direction" and "perpendicular direction," respectively. Then, as shown in the upper left column of Figure 2, when the azimuth resolution of the radar wave analysis processing is high, even if the wave crests W have a short wave wavelength, adjacent wave crests W are unlikely to overlap each other in the radar scan image R within analysis area A due to the high azimuth resolution, and each wave crest W is not stretched much. On the other hand, as shown in the upper right column of Figure 2, even when the azimuth resolution of the radar wave analysis processing is low, even if the wave crests W have a short wave wavelength, adjacent wave crests W are unlikely to overlap each other in the radar scan image R within analysis area A regardless of the low azimuth resolution, and each wave crest W is only stretched slightly.

[0027] Therefore, in the present disclosure, the "depth direction" and "width direction" of the analysis area A are set to be "parallel" and "perpendicular" to the direction directly facing the ocean wave direction, respectively, as shown in the upper part of Figure 2. Therefore, in the present disclosure, even when the azimuth resolution of the radar wave analysis process is low because the radar is small or the radar frequency is low, it is possible to calculate at least one of the ocean wave height, ocean wave wavelength, ocean wave direction, and ocean wave speed with high accuracy, even for wave crests W with short ocean wave wavelengths.

[0028] (Configuration of the radar wave analysis system of the present disclosure) The configuration of the radar wave analysis system of the present disclosure is shown in Fig. 3. The radar wave analysis system S includes a radar transmitter / receiver 1, a radar wave analysis device 2, and a radar display device 3. The radar transmitter / receiver 1 includes a radar transmitter 11, a transmitter / receiver switch 12, a radar antenna 13, and a radar receiver 14, and transmits radar irradiated waves and receives radar reflected waves. The radar wave analysis device 2 includes a radar wave analyzer 21, a wave direction calculator 22, an analysis area direction setting unit 23, and an analysis area calculator 24, and is realized by installing the radar wave analysis program shown in Fig. 4 on a computer. The radar display device 3 displays the results of the radar wave analysis.

[0029] Here, when a radar wave analysis system S equipped with a large radar transceiver 1 is mounted on a ship or the like, the radar beam width is narrow and the azimuth resolution of the radar wave analysis process is high. Alternatively, the azimuth resolution of the radar wave analysis process is high even when the radar frequency is high. On the other hand, when a radar wave analysis system S equipped with a small radar transceiver 1 is mounted on a drone D or an aircraft or the like, the radar beam width is wide and the azimuth resolution of the radar wave analysis process is low. Alternatively, the azimuth resolution of the radar wave analysis process is low even when the radar frequency is low. The present disclosure has an inventive effect that is greater when the azimuth resolution of the radar wave analysis process is low, but can also be applied when the azimuth resolution of the radar wave analysis process is high.

[0030] (Procedure of radar wave analysis processing according to the present disclosure) The procedure for the radar wave analysis processing of the present disclosure is shown in Fig. 4. Specific examples of the radar wave analysis processing of the present disclosure are shown in Figs. 5 and 6. First, an overview will be given. The analysis area direction setting unit 23 sets the "depth direction" and "width direction" of the rectangular analysis area A in which wave analysis is performed to the "parallel direction" and "perpendicular direction" facing the wave direction, respectively (step S2). The radar wave analysis unit 21 performs wave analysis of at least one of the wave height, wave wavelength, and wave speed of the waves, based on the radar scan image R within the analysis area A set by the analysis area direction setting unit 23 (step S6).

[0031] Next, details will be explained. The ocean wave direction calculation unit 22 initially sets an initial analysis area I as the analysis area A, and initially calculates the ocean wave direction φ based on the radar scan image R within the initial analysis area I (step S1). In the upper left column of Fig. 5 and the upper left column of Fig. 6, the analysis area calculation unit 24 initially sets the initial analysis area I to an initial direction φ = 0, a predetermined distance R, and a predetermined size d as viewed from the radar ocean wave analysis system S. Here, the predetermined distance R may be any distance as long as the ocean wave crests are displayed, and the predetermined size d may be approximately 1000 m × approximately 1000 m (a size smaller than that of conventional technology), taking into account the wavelength of swells (several hundred meters) and the like.

[0032] In the upper right column of FIG. 5, the wave direction φ of the ocean waves may be initially calculated simply based on a real space analysis of the radar scan image R in the initial analysis region I. In the lower left column of FIG. 5, the wave direction φ of the ocean waves may be initially calculated with high accuracy based on a wave number space analysis of the radar scan image R in the initial analysis region I. Here, in Fourier space F, the wave number coordinate (k x , k y ) has the maximum peak strength, so the wave direction φ is φ=tan -1 (k y / k x ) is calculated as follows.

[0033] The analysis domain direction setting unit 23 sets the "depth direction" and "width direction" of the analysis domain A to be "parallel" and "perpendicular" to the facing direction of the wave direction φ initially calculated by the wave direction calculation unit 22 (step S2). In the lower right column of FIG. 5, the analysis domain calculation unit 24 sets the analysis domain A to the facing direction of the wave direction φ, a predetermined distance R, and a predetermined size d' as seen from the radar wave analysis system S. Here, the facing direction of the wave direction φ may be a direction facing or facing away from the wave direction φ. The predetermined size d' may be the same as or different from the initial predetermined size d, and may be approximately 1000 m x approximately 1000 m (a smaller size than in the prior art) taking into account the wavelength of swells (several hundred meters).

[0034] The radar wave analysis unit 21 performs wave analysis of at least one of the wave height h, wave wavelength λ, and wave speed v based on the radar scan image R within the analysis area A set by the analysis area direction setting unit 23 (step S6). The radar display device 3 displays the radar wave analysis results (step S7). Steps S6 and S7 are repeated until the radar wave analysis is completed (step S8). In the lower right column of Fig. 5, at least one of the wave height h, wave wavelength λ, and wave speed v is calculated and displayed.

[0035] In this way, even when the azimuth resolution of the radar wave analysis process is low, it is sometimes possible to calculate the wave direction φ of the waves with a certain degree of accuracy. After initializing the initial analysis area I, the analysis area A can be set with high accuracy simply by initially calculating the wave direction φ of the waves.

[0036] However, when the azimuth resolution of the radar wave analysis process is low, it may not be possible to calculate the wave direction φ with a certain degree of accuracy, and it may not be possible to set the analysis area A with high accuracy simply by initially setting the initial analysis area I and then initially calculating the wave direction φ. In the upper right column of Figure 6, the analysis area calculation unit 24 sets the analysis area A at a predetermined distance R and a predetermined size d' as viewed from the radar wave analysis system S, in the facing direction of the wave direction φ. Here, the "depth direction" of the analysis area A is "parallel" to the facing direction of the calculated wave direction φ, but is not "parallel" to the facing direction of the actual wave direction φ'.

[0037] The ocean wave direction calculation unit 22 recalculates the ocean wave direction φ' based on the radar scan image R within the analysis area A set by the analysis area direction setting unit 23 (step S3). The ocean wave direction calculation unit 22 determines whether the facing direction of the ocean wave direction φ' is "parallel" to the "depth direction" of the analysis area A set by the analysis area direction setting unit 23 (step S4).

[0038] When the wave direction calculation unit 22 determines that the facing direction is not "parallel" to the "depth direction" (step S5, NO), the analysis area direction setting unit 23 sets the "depth direction" and "width direction" of the analysis area A to "parallel" and "perpendicular" to the facing direction with respect to the wave direction φ' calculated again by the wave direction calculation unit 22 (second step S2). Steps S2 to S5 are repeated until the setting of the analysis area A is completed (step S5, YES).

[0039] When the ocean wave direction calculation unit 22 determines that the facing direction is "parallel" to the "depth direction" (step S5, YES), the analysis area direction setting unit 23 maintains the "depth direction" and "width direction" of the analysis area A as "parallel" and "perpendicular" to the facing direction with respect to the ocean wave direction φ initially calculated by the ocean wave direction calculation unit 22 (first step S2). Steps S6 and S7 are repeated until the radar ocean wave analysis is completed (step S8).

[0040] In the lower left column of Fig. 6, the analysis area calculation unit 24 sets an analysis area A at a predetermined distance R and a predetermined size d' in the facing direction of the ocean wave direction φ' as seen from the radar ocean wave analysis system S. Here, the "depth direction" of the analysis area A is "parallel" to the facing direction of the calculated ocean wave direction φ', and is "parallel" to the facing direction of the actual ocean wave direction φ'. In the lower right column of Fig. 6, at least one of the ocean wave height h, ocean wave wavelength λ, and ocean wave speed v is calculated and displayed.

[0041] In this way, when the azimuth resolution of the radar wave analysis process is low, it may not be possible to calculate the wave direction φ with a certain degree of accuracy. However, by recalculating the wave direction φ' and then re-setting the analysis area A, the analysis area A can be set with high accuracy. [Industrial Applicability]

[0042] The radar wave analysis device, radar wave analysis program, and radar wave analysis drone disclosed herein can calculate at least one of wave height, wave wavelength, wave direction, and wave speed with high accuracy even when the azimuth resolution of the radar wave analysis process is low due to the radar being small (especially when the radar is mounted on a drone or aircraft, etc.) or the radar frequency being low. [Explanation of symbols]

[0043] R: Radar scan image I: Initial analysis area A:Analysis area F: Fourier space W: wave crest S: Radar wave analysis system D: Radar wave analysis drone 1: Radar transmitter and receiver 2: Radar wave analyzer 3: Radar display device 11: Radar transmitter 12: Transmission / reception switching unit 13: Radar antenna 14: Radar receiver 21: Radar wave analysis section 22: Wave direction calculation part 23: Analysis area direction setting part 24:Analysis area calculation section

Claims

1. A radar wave analysis device that performs wave analysis using a radar, an analysis area direction setting unit that sets the depth direction and width direction of a rectangular analysis area in which wave analysis is performed to directions parallel and perpendicular to the facing direction of the waves, respectively; a radar wave analysis unit that performs wave analysis of at least one of wave height, wave wavelength, and wave speed based on a radar scan image within the analysis area set by the analysis area direction setting unit; A radar wave analysis device comprising:

2. and a wave direction calculation unit that initially sets an initial analysis area as the analysis area and initially calculates a wave direction based on a radar scan image within the initial analysis area. The analysis area direction setting unit sets the depth direction and width direction of the analysis area to directions parallel and perpendicular to the facing direction of the wave direction initially calculated by the wave direction calculation unit, respectively.

2. The radar wave analysis device according to claim 1, wherein:

3. The ocean wave direction calculation unit determines whether the facing direction of the ocean wave direction recalculated based on the radar scan image in the analysis area set by the analysis area direction setting unit is parallel to the depth direction of the analysis area set by the analysis area direction setting unit, When the wave direction calculation unit determines that the facing direction is not parallel to the depth direction, the analysis area direction setting unit sets the depth direction and width direction of the analysis area to parallel and perpendicular directions, respectively, to the facing direction of the wave direction recalculated by the wave direction calculation unit.

3. The radar wave analysis device according to claim 2, wherein:

4. 4. A radar wave analysis program for causing a computer to execute each processing step performed by each processing unit included in the radar wave analysis device according to claim 1.

5. A radar wave analysis drone comprising the radar wave analysis device according to any one of claims 1 to 3 and a radar transmitting and receiving device for performing wave analysis.

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