Radar signal processing device, radar signal processing program, radar image display device, and autonomous navigation device

Abstract

To automatically adjust a control method of a clutter suppression parameter both when a ship or the like is autonomously navigated by using a radar image or a sonar image and when a crew or the like makes a navigation determination.SOLUTION: In preparation for autonomous navigation of a ship or the like, a clutter suppressor 2 outputs a radar image after clutter suppression on the basis of both or one of ocean wave information and rain / snow information acquired from the outside. A clutter extraction unit 3 subtracts the radar image after the clutter suppression from the radar image before the clutter suppression, and automatically outputs the radar image after the clutter extraction. A target signal extraction unit 1 automatically outputs a radar image after target signal extraction on the basis of both or one of target information and land information acquired from the outside in preparation for navigation determination by a crew or the like.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a technology for performing autonomous navigation using radar images.

Background Art

[0002] There has conventionally been a technology for performing autonomous navigation of ships and the like using radar images or sonar images. By performing autonomous navigation of ships and the like, the safety of ships and the like can be improved, and the shortage of crew and the like can be eliminated. On the other hand, by passing through the navigation judgment of crew and the like, obstacles of ships and the like can be avoided in areas where ships and the like are congested in straits and the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, when performing autonomous navigation of ships and the like, by using a radar image including not only the target signal of ships and the like but also clutter such as waves or rain and snow, the influence of weather or sea conditions can be avoided, and efficient autonomous navigation can be performed. On the other hand, when passing through the navigation judgment of crew and the like, by using a radar image that suppresses clutter such as waves or rain and snow and emphasizes the target signal of ships and the like, stable target display can be performed regardless of the skills of crew and the like.

[0005] That is, when performing autonomous navigation of ships and the like and when passing through the navigation judgment of crew and the like, the required radar images (clutter such as waves or rain and snow or the target signal of ships and the like) may be different, and the control method of the suppression parameter of clutter such as waves or rain and snow may be different.

[0006] Here, in Patent Document 1, for the sensor signal of one system of radar device, two systems of signal processing with different parameters are performed, and two systems of screen information obtained by the two systems of signal processing are displayed simultaneously. Therefore, when performing autonomous navigation of a ship or the like, and when passing through the navigation judgment of a crew member or the like, two systems of signal processing with different control methods for clutter suppression parameters are performed, and two systems of required radar images (clutter or target signals) can be displayed simultaneously.

[0007] However, in Patent Document 1, among the two systems of signal processing, the parameters are automatically adjusted in one signal processing, while the user adjusts the parameters in the other signal processing. Therefore, when performing autonomous navigation of a ship or the like, and when passing through the navigation judgment of a crew member or the like, if the crew members are involved in the navigation judgment all the time, the crew members can immediately and optimally adjust the control method of the clutter suppression parameters. However, if the crew members are involved in the navigation judgment only when necessary, the crew members cannot immediately and optimally adjust the control method of the clutter suppression parameters.

[0008] Therefore, in order to solve the above problems, an object of the present disclosure is to automatically adjust the control method of clutter suppression parameters both when performing autonomous navigation of a ship or the like and when passing through the navigation judgment of a crew member or the like using a radar image or a sonar image.

[0009] And, in Patent Document 1, after controlling the clutter suppression parameters of clutter such as waves or rain and snow for the sensor signal of one system of radar device, a radar image including clutter such as waves or rain and snow is displayed. However, one system of radar device has advantages or disadvantages in terms of resolution, maximum distance, or visible area depending on the frequency band, antenna length, or mounting position. Therefore, it was not possible to clearly determine whether a radar image of one system appropriately includes clutter such as waves or rain and snow when performing autonomous navigation of a ship or the like.

[0010] Therefore, in order to solve the above problems, another object of the present disclosure is to determine whether clutter such as waves or rain and snow is appropriately included regardless of the frequency band, antenna length, or mounting position when performing autonomous navigation of a ship or the like using radar video or sonar video.

[0011] Furthermore, in Patent Document 1, for the sensor signal of one radar device, after controlling the clutter suppression parameter of clutter such as waves or rain and snow, a radar video that emphasizes the target signal of a ship or the like is displayed. However, one radar device has advantages or disadvantages in terms of resolution, maximum distance, or visible area depending on the frequency band, antenna length, or mounting position. Therefore, it has not been possible to clearly determine whether or not the target signal of a ship or the like is appropriately emphasized when passing through the navigation judgment of a ship's crew or the like in one radar video.

[0012] Therefore, in order to solve the above problems, another object of the present disclosure is to determine whether or not the target signal of a ship or the like is appropriately emphasized regardless of the frequency band, antenna length, or mounting position when passing through the navigation judgment of a ship's crew or the like using radar video or sonar video.

Means for Solving the Problems

[0013] In order to solve the above problems, when performing autonomous navigation of a ship or the like, a radar video after clutter suppression is output based on both or one of the wave information and rain and snow information acquired from the outside. Then, the radar video after clutter suppression is subtracted from the radar video before clutter suppression to automatically output a radar video after clutter extraction.

[0014] Specifically, the present disclosure suppresses both or one of the wave clutter and the rain / snow clutter in the radar image before clutter suppression based on both or one of the wave information and the rain / snow information acquired from the outside, and outputs a radar image after clutter suppression. A clutter suppression unit, and subtracts the radar image after the clutter suppression from the radar image before the clutter suppression to extract both or one of the wave clutter and the rain / snow clutter, and outputs a radar image after the clutter extraction. A radar signal processing apparatus, characterized by comprising a clutter extraction unit.

[0015] According to this configuration, when performing autonomous navigation of a ship or the like using a radar image or a sonar image, the control method of the clutter suppression parameter can be automatically adjusted.

[0016] Further, in the present disclosure, the clutter extraction unit separates and extracts the wave clutter from the rain / snow clutter based on the suppression parameter of the wave clutter with respect to the radar image after the clutter extraction, or separates and extracts the rain / snow clutter from the wave clutter based on the suppression parameter of the rain / snow clutter with respect to the radar image after the clutter extraction. A radar signal processing apparatus, characterized by extracting.

[0017] According to this configuration, when performing autonomous navigation of a ship or the like using a radar image or a sonar image, the wave clutter and the rain / snow clutter can be automatically separated and extracted.

[0018] Further, in the present disclosure, the clutter suppression unit performs feedback control on both or one of the suppression parameters of the wave clutter and the rain / snow clutter based on the degree of coincidence between the radar image after the clutter extraction (current or past radar image) and both or one of the wave information and the rain / snow information (the current or past information). A radar signal processing apparatus, characterized by the above.

[0019] According to this configuration, when performing autonomous navigation of a ship or the like using radar images or sonar images, the control method of the clutter suppression parameter can be automatically feedback-controlled based on the current wave information and rain / snow information (highly reliable information predicted externally) or past wave information and rain / snow information (more reliable information actually observed).

[0020] In order to solve the above problems, when performing autonomous navigation of a ship or the like, a plurality of radar devices (the mounting positions are necessarily different) having the same or different frequency bands or antenna lengths are provided to output radar images after clutter extraction for each of them.

[0021] Here, the plurality of radar devices complement each other's disadvantages in terms of resolution, maximum distance, or visible area according to the frequency band, antenna length, or mounting position. Therefore, when there are more clutters displayed in one radar image compared to the other radar image, the clutter suppression parameter is feedback-controlled so that the displayed clutter is further displayed in one radar image.

[0022] Specifically, the present disclosure further includes a radar image comparison unit that, for each of the radar images before clutter suppression obtained from a plurality of radar transceiver devices having the same or different frequency bands or antenna lengths, executes clutter suppression processing and clutter extraction processing respectively, and when there are more clutters displayed in a certain radar image after clutter extraction compared to other radar images after clutter extraction, feedback-controls the suppression parameter of both or one of the wave clutter and the rain / snow clutter so that the displayed clutter is further displayed in the certain radar image after clutter extraction. The radar signal processing device is characterized by this.

[0023] According to this configuration, when performing autonomous navigation of a ship or the like using radar images or sonar images, it is possible to determine whether or not to appropriately include clutter such as waves or rain and snow regardless of the frequency band, antenna length, or mounting position. And when it is determined that the clutter is appropriately included, the clutter can be further displayed.

[0024] Further, in the present disclosure, the radar image comparison unit feeds back control of suppression parameters of both or one of the wave clutter and the rain and snow clutter so that the displayed clutter is further displayed by enhancing suppression of both or one of the wave clutter and the rain and snow clutter in the radar image after extraction of the clutter. A radar signal processing apparatus characterized by the above.

[0025] According to this configuration, when performing autonomous navigation of a ship or the like using radar images or sonar images, if the clutter is further suppressed by the clutter suppression unit, the clutter can be further displayed when it is determined that the clutter can be appropriately included by the clutter extraction unit.

[0026] In order to solve the above problems, in preparation for the case of passing through the navigation judgment of a crew member or the like, based on both or one of the target information and land information (highly reliable information not depending on radar) acquired from the outside, the radar image after extraction of the target signal is automatically output.

[0027] Specifically, the present disclosure further includes a target signal extraction unit that extracts both or one of the target signal and the land signal from the radar image before clutter suppression based on both or one of the target information and land information acquired from the outside, suppresses both or one of the wave clutter and the rain and snow clutter, and outputs a radar image after extraction of the target signal. A radar signal processing apparatus characterized by the above.

[0028] According to this configuration, when using radar images or sonar images and making navigation judgments by crew members or the like, the control method of the clutter suppression parameters can be automatically adjusted.

[0029] Further, in the present disclosure, the target signal extraction unit performs feedback control on the suppression parameters of both or one of the wave clutter and the rain and snow clutter based on the degree of coincidence between the radar image after the target signal extraction (current or past radar image) and both or one of the target information and the land information (current or past information). It is a radar signal processing device characterized by this.

[0030] According to this configuration, when using radar images or sonar images and making navigation judgments by crew members or the like, based on the current target information and land information (high-reliability information obtained externally) or past target information and land information (even higher-reliability information verified afterwards), the control method of the clutter suppression parameters can be automatically feedback-controlled.

[0031] Further, in the present disclosure, the clutter suppression unit performs feedback control on the suppression parameters of both or one of the wave clutter and the rain and snow clutter based on the degree of coincidence between the radar image after the clutter suppression and the radar image after the target signal extraction. It is a radar signal processing device characterized by this.

[0032] According to this configuration, when performing autonomous navigation of a ship or the like using radar images or sonar images, based on the radar image after target signal extraction (high-reliability information based on target information and land information), the control method of the clutter suppression parameters can be automatically feedback-controlled so as not to suppress the target signal in the radar image after clutter suppression.

[0033] In order to solve the above problems, in preparation for the case where the navigation judgment of the crew or the like is involved, for a plurality of radar devices (the mounting positions are necessarily different) having the same or different frequency bands or antenna lengths, radar images after extracting each target signal are output.

[0034] Here, the plurality of radar devices complement each other's disadvantages in terms of resolution, maximum distance, or visible area according to the frequency band, antenna length, or mounting position. Therefore, when there is a target signal that is not displayed in one radar image as opposed to the other radar image, the clutter suppression parameter is feedback-controlled so that the non-displayed target signal is redisplayed in one radar image.

[0035] Specifically, the present disclosure further includes a radar image comparison unit that, for each of the radar images before clutter suppression acquired from a plurality of radar transceiver devices having the same or different frequency bands or antenna lengths, executes target signal extraction processing on the radar images before clutter suppression, and when there is a target signal that is not displayed in a certain radar image after target signal extraction among the radar images after each target signal extraction, as opposed to other radar images after target signal extraction, feedback-controls the suppression parameter of both or one of the sea clutter and the rain and snow clutter so that the non-displayed target signal is redisplayed in the certain radar image after target signal extraction. The radar signal processing device is characterized by this.

[0036] According to this configuration, when using a radar image or a sonar image and involving the navigation judgment of the crew or the like, it is possible to determine whether to appropriately emphasize the target signal of a ship or the like regardless of the frequency band, antenna length, or mounting position. And when it is determined that the target signal of a ship or the like is not appropriately emphasized, the target signal of a ship or the like can be redisplayed.

[0037] Further, in the present disclosure, the radar image comparison unit feedback-controls suppression parameters for both or one of the sea clutter and the rain and snow clutter so that the target signal that is not displayed is redisplayed due to weakened suppression of both or one of the sea clutter and the rain and snow clutter in the radar image after a certain target signal is extracted. The present disclosure relates to a radar signal processing apparatus characterized by this.

[0038] According to this configuration, when using a radar image or a sonar image and making a navigation judgment by a crew member or the like, if it is determined that the target signal of a ship or the like is not appropriately emphasized because clutter is overly suppressed, the target signal of the ship or the like can be redisplayed.

[0039] Further, the present disclosure relates to a radar signal processing program for causing a computer to execute each processing step executed by each processing unit included in the radar signal processing apparatus described above.

[0040] According to this configuration, a program having the effects described above can be provided.

[0041] Further, the present disclosure relates to a radar image display apparatus that separately displays the radar image after clutter extraction output by the radar signal processing apparatus described above and the radar image after target signal extraction output by the radar signal processing apparatus described above.

[0042] According to this configuration, an image display apparatus having the effects described above can be provided.

[0043] Further, the present disclosure relates to an autonomous navigation apparatus that performs autonomous navigation using the radar image after clutter extraction output by the radar signal processing apparatus described above and the radar image after target signal extraction output by the radar signal processing apparatus described above.

[0044] According to this configuration, an autonomous navigation apparatus having the effects described above can be provided.

[0045] In addition, the inventions disclosed above can be combined as much as possible.

Effect of the Invention

[0046] In this way, the present disclosure can automatically adjust the control method of clutter suppression parameters both when performing autonomous navigation of ships or the like using radar images or sonar images and when passing through the navigation judgment of crew members or the like.

[0047] And the present disclosure can determine whether to appropriately include clutter such as waves or rain and snow regardless of the frequency band, antenna length, or mounting position when performing autonomous navigation of ships or the like using radar images or sonar images.

[0048] And the present disclosure can determine whether to appropriately emphasize the target signal of ships or the like regardless of the frequency band, antenna length, or mounting position when passing through the navigation judgment of crew members or the like using radar images or sonar images.

Brief Description of the Drawings

[0049]

Figure 1

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Figure 14

Embodiments for Carrying Out the Invention

[0050] Embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of the implementation of the present disclosure, and the present disclosure is not limited to the following embodiments.

[0051] (Configuration of the Radar System of the Present Disclosure) The configuration of the radar system of the present disclosure is shown in FIG. 1. The radar system R includes a radar transceiver A, a target information acquisition device T, a weather information acquisition device M, a radar signal processing device S, a radar image display device D, and an autonomous navigation device N. The radar signal processing device S includes a target signal extraction unit 1, a clutter suppression unit 2, and a clutter extraction unit 3, and can be realized by installing the radar signal processing program shown in FIGS. 2 and 4 on a computer.

[0052] As shown in FIGS. 2 and 3, in preparation for the case where navigation judgment is made by a crew member or the like, based on both or one of the target information and land information (highly reliable information not based on radar) acquired from the outside, the radar image after target signal extraction is automatically output.

[0053] As shown in FIGS. 4 to 6, in preparation for autonomous navigation of a ship or the like, a radar image after clutter suppression is output based on both or one of the wave information and rain / snow information acquired from the outside. Then, the radar image after clutter suppression is subtracted from the radar image before clutter suppression to automatically output the radar image after clutter extraction.

[0054] (Procedure of target signal extraction process of the present disclosure) The procedure of the target signal extraction process of the present disclosure is shown in FIG. 2. A specific example of the target signal extraction process of the present disclosure is shown in FIG. 3. The radar transceiver A transmits an irradiation radar signal and receives a reflected radar signal. The target information acquisition device T acquires both or one of the target information (AIS information, buoy identification information, etc.) and land information from an external information source. However, for small boats, yachts, falling objects, etc., the target information acquisition device T cannot acquire information, and the radar transceiver A can acquire an image.

[0055] Based on both or one of the target information and land information acquired from the outside, the target signal extraction unit 1 extracts both or one of the target signal and the land signal from the radar image before clutter suppression, suppresses both or one of the wave clutter and the rain / snow clutter, and outputs the radar image after target signal extraction (step S1).

[0056] That is, the target signal extraction unit 1 controls the suppression parameters of the wave clutter and the rain / snow clutter so as not to suppress the target signal and the land signal at the target position and the land position included in the target information and the land information, and to suppress the wave clutter and the rain / snow clutter.

[0057] In the left column of FIG. 3, in the radar image before clutter suppression, the land signal is not buried in the sea clutter and rain / snow clutter, and the target signal is buried in the sea clutter and rain / snow clutter. In the middle column of FIG. 3, in the radar image during clutter suppression, the target information (AIS information, buoy identification information, etc.) includes the target position, and the land information includes the land position. In the right column of FIG. 3, in the radar image after target signal extraction, the land signal is not buried in the sea clutter and rain / snow clutter, and the target signal (including small ships, yachts, and falling objects, etc.) is also not buried in the sea clutter and rain / snow clutter.

[0058] The target signal extraction unit 1 feedback-controls the suppression parameters of both or one of the sea clutter and rain / snow clutter based on the degree of coincidence between the radar image after target signal extraction (current or past radar image) and both or one of the target information and land information (the current or past information) (Steps S2 to S4).

[0059] That is, the target signal extraction unit 1 determines the degree of coincidence between the radar image after target signal extraction and the target information and land information (Step S2). Then, when the degree of coincidence is low (Step S3, NO), the target signal extraction unit 1 feedback-controls the suppression parameters of the sea clutter and rain / snow clutter (Step S4, right column of FIG. 3) and returns to Step S2. On the other hand, when the degree of coincidence is high (Step S3, YES), the target signal extraction unit 1 finishes the feedback control of the suppression parameters of the sea clutter and rain / snow clutter and proceeds to Step S5.

[0060] Here, when the target signal extraction unit 1 determines the degree of coincidence between the radar image after the extraction of the "current" target signal, the "current" target information, and land information (highly reliable information obtained externally), it can perform high-precision feedback control on the suppression parameters of the "current" sea clutter and rain / snow clutter. Then, when the target signal extraction unit 1 determines the degree of coincidence between the radar image after the extraction of the "past" target signal, the "past" target information, and land information (even more highly reliable information verified afterwards), it can perform even higher-precision feedback control on the suppression parameters of the "current" sea clutter and rain / snow clutter.

[0061] The radar image display device D displays the radar image after the extraction of the target signal output by the target signal extraction unit 1 (after coordinate transformation, coordinate rotation, range adjustment, etc.) (step S5).

[0062] In this way, when using a radar image or sonar image and passing through the navigation judgment of a crew member or the like, the control method of the clutter suppression parameter can be automatically adjusted. And based on the current target information and land information (highly reliable information obtained externally) or past target information and land information (even more highly reliable information verified afterwards), the control method of the clutter suppression parameter can be automatically feedback-controlled.

[0063] (Procedure of clutter extraction process of the present disclosure) The procedure of the clutter extraction process of the present disclosure is shown in FIG. 4. Specific examples of the clutter extraction process of the present disclosure are shown in FIGS. 5 and 6. The radar transceiver device A transmits an irradiation radar signal and receives a reflected radar signal. The weather information acquisition device M acquires both or one of the wave information (including wind direction and wind speed information, etc.) and rain / snow information from an external information source.

[0064] Based on both or either of the wave information and the rain / snow information acquired from the outside, the clutter suppression unit 2 suppresses both or either of the wave clutter and the rain / snow clutter in the radar image before clutter suppression, and outputs the radar image after clutter suppression (step S11).

[0065] That is, the clutter suppression unit 2 controls the suppression parameters of the wave clutter and the rain / snow clutter so as to suppress the wave clutter and the rain / snow clutter in the wave distribution and the rain / snow distribution included in the wave information and the rain / snow information. Here, the wave distribution included in the wave information is strong around a ship or the like, strong on the upwind side of the ship or the like, and weak on the downwind side of the ship or the like. On the other hand, the rain / snow distribution included in the rain / snow information extends over a wide range, including the surroundings of a ship or the like.

[0066] In the upper left column of FIG. 5, in the radar image before clutter suppression, the target signal (land not shown) is buried in the wave clutter and the rain / snow clutter. In the upper right column of FIG. 5, in the radar image during clutter suppression, the wave information (including wind direction and wind speed information, etc.) includes the wave distribution, and the rain / snow information includes the rain / snow distribution. In the lower left column of FIG. 5, in the radar image after clutter suppression, the target signal (land not shown) is not buried in the wave clutter and the rain / snow clutter.

[0067] The clutter suppression unit 2 performs feedback control on the suppression parameters of both or either of the wave clutter and the rain / snow clutter based on the degree of coincidence between the radar image after clutter suppression and the radar image after target signal extraction (steps S12 to S14).

[0068] That is, the clutter suppression unit 2 determines the degree of coincidence between the radar image after clutter suppression (lower left column of FIG. 5) and the radar image after target signal extraction (right column of FIG. 3 and lower right column of FIG. 5) (step S12). Then, when the degree of coincidence is low (step S13, NO), the clutter suppression unit 2 performs feedback control on the suppression parameters of the sea clutter and rain / snow clutter (step S14, lower right column of FIG. 5) and returns to step S12. On the other hand, when the degree of coincidence is high (step S13, YES), the clutter suppression unit 2 finishes the feedback control of the suppression parameters of the sea clutter and rain / snow clutter and proceeds to step S15.

[0069] Here, the target signal extraction unit 1 and the clutter suppression unit 2 may execute the radar signal processing program shown in FIGS. 2 and 4 in parallel or in this order. And the target signal extraction unit 1 and the clutter suppression unit 2 may control the suppression parameters of the sea clutter and rain / snow clutter to be approximately the same value or to slightly different values.

[0070] In this way, when performing autonomous navigation of a ship or the like using a radar image or a sonar image, based on the radar image after target signal extraction (information with high reliability based on target information and land information), the control method of the clutter suppression parameter can be automatically feedback-controlled so as not to suppress the target signal in the radar image after clutter suppression.

[0071] The clutter extraction unit 3 subtracts the radar image after clutter suppression from the radar image before clutter suppression to extract both or one of the sea clutter and rain / snow clutter and outputs the radar image after clutter extraction (step S15).

[0072] Here, the wave information and rain / snow information are not the actually observed information, but the predicted information for a short time after the present, and are information over a wide range not limited to the surroundings of a ship or the like. On the other hand, the radar image after clutter extraction is not the predicted information for a short time after the present, but the actually observed information, and is pinpoint information limited to the surroundings of a ship or the like.

[0073] The clutter extraction unit 3 separates and extracts the wave clutter from the rain / snow clutter based on the suppression parameter of the wave clutter with respect to the radar image after clutter extraction. Alternatively, the clutter extraction unit 3 separates and extracts the rain / snow clutter from the wave clutter based on the suppression parameter of the rain / snow clutter with respect to the radar image after clutter extraction (step S16).

[0074] That is, the clutter extraction unit 3 sets the suppression parameter of the wave (or rain / snow) clutter with respect to the radar image after extraction of the wave and rain / snow clutter, and outputs the radar image after suppression of the wave (or rain / snow) clutter. Then, the clutter extraction unit 3 subtracts the radar image after suppression of the wave (or rain / snow) clutter from the radar image after extraction of the wave and rain / snow clutter, and outputs the radar image after separation and extraction of the rain / snow (or wave) clutter.

[0075] In the upper left column of FIG. 6, in the radar image before clutter suppression, the target signal (land not shown) is buried in the wave clutter and the rain / snow clutter. In the upper right column of FIG. 6, in the radar image after clutter suppression, the target signal (land not shown) is not buried in the wave clutter and the rain / snow clutter. In the lower left column of FIG. 6, in the radar image after clutter extraction, the wave clutter and the rain / snow clutter are extracted. Here, the suppression parameter of the wave (or rain / snow) clutter is set, and the radar image after suppression of the wave (or rain / snow) clutter is subtracted. In the lower right column of FIG. 6, in the radar image after separation and extraction of the wave (or rain / snow) clutter, the wave (or rain / snow) clutter is extracted.

[0076] The clutter suppression unit 2 performs feedback control of suppression parameters for both or either of the wave clutter and the rain / snow clutter based on the degree of coincidence between the radar image after clutter extraction (current or past radar image) and both or either of the wave information and the rain / snow information (current or past information) (Steps S17 to S19).

[0077] That is, the clutter suppression unit 2 determines the degree of coincidence between the radar image after clutter extraction and the wave information and the rain / snow information (Step S17). Then, when the degree of coincidence is low (Step S18, NO), the clutter suppression unit 2 performs feedback control of the suppression parameters for the wave clutter and the rain / snow clutter (Step S19, lower right column of FIG. 6), and returns to Step S12 (it may only return to Step S17 without returning all the way to Step S12). On the other hand, when the degree of coincidence is high (Step S18, YES), the clutter suppression unit 2 finishes the feedback control of the suppression parameters for the wave clutter and the rain / snow clutter, and proceeds to Step S20.

[0078] Here, when the clutter suppression unit 2 determines the degree of coincidence between the radar image after clutter extraction at “present” and the wave information and the rain / snow information at “present” (information with high reliability predicted externally), it can perform high-precision feedback control of the suppression parameters for the wave clutter and the rain / snow clutter at “present”. And when the clutter suppression unit 2 determines the degree of coincidence between the radar image after clutter extraction in “the past” and the wave information and the rain / snow information in “the past” (more reliable information actually observed), it can perform even higher-precision feedback control of the suppression parameters for the wave clutter and the rain / snow clutter at “present”.

[0079] The radar image display device D displays the radar image after clutter extraction (after coordinate transformation, coordinate rotation, range adjustment, etc.) output by the clutter extraction unit 3 (Step S20).

[0080] In this way, when performing autonomous navigation of a ship or the like using radar images or sonar images, the control method of clutter suppression parameters can be automatically adjusted. And the wave clutter and rain / snow clutter can be automatically separated and extracted. Furthermore, based on the current wave information and rain / snow information (highly reliable information predicted externally) or past wave information and rain / snow information (more highly reliable information actually observed), the control method of clutter suppression parameters can be automatically feedback-controlled.

[0081] (Configuration of the Radar System of the Present Disclosure) The configuration of the radar system of the present disclosure is also shown in FIG. 7. The radar system R includes radar transceiver devices A-1, A-2, a target information acquisition device T, a weather information acquisition device M, a radar signal processing device S, a radar image display device D, and an autonomous navigation device N. The radar signal processing device S includes target signal extraction units 1-1, 1-2, clutter suppression units 2-1, 2-2, clutter extraction units 3-1, 3-2, and a radar image comparison unit 4, and can be realized by installing the radar signal processing program shown in FIGS. 2, 4, 8, and 11 in a computer.

[0082] As shown in FIGS. 8 to 10, in preparation for the case where navigation decisions are made by crew members or the like, for a plurality of radar transceiver devices (the mounting positions are necessarily different) having the same or different frequency bands or antenna lengths, the radar images after extracting each target signal are output.

[0083] Here, the plurality of radar transceiver devices complement each other's disadvantages in terms of resolution, maximum distance, or visible area according to the frequency band, antenna length, or mounting position. Therefore, when there are target signals that are not displayed in one radar image but are different from the other radar image, the clutter suppression parameters are feedback-controlled so that the non-displayed target signals are redisplayed in one radar image.

[0084] As shown in FIGS. 11 to 13, in preparation for autonomous navigation of a ship or the like, for a plurality of radar transceiver devices having the same or different frequency bands or antenna lengths (the mounting positions are necessarily different), radar images after clutter extraction for each are output.

[0085] Here, the plurality of radar transceiver devices complement each other's weaknesses in terms of resolution, maximum distance, or visible area according to the frequency band, antenna length, or mounting position. Therefore, when there are more clutters displayed in one radar image compared to the other radar image, the clutter suppression parameter is feedback-controlled so that the clutters to be displayed are further displayed in one radar image.

[0086] (Procedure of Radar Image Comparison Processing after Target Signal Extraction of the Present Disclosure) The procedure of the radar image comparison processing after target signal extraction of the present disclosure is shown in FIG. 8. Specific examples of the radar image comparison processing after target signal extraction of the present disclosure are shown in FIGS. 9 and 10. The radar signal processing device S acquires radar images before clutter suppression from a plurality of radar transceiver devices A-1 and A-2 having the same or different frequency bands or antenna lengths (the mounting positions are necessarily different) (step S21). The target signal extraction units 1-1 and 1-2 execute target signal extraction processing (steps S1 to S4) on the radar images before clutter suppression for each (step S22).

[0087] Here, the plurality of radar transceiver devices A-1 and A-2 complement each other's weaknesses in terms of resolution, maximum distance, or visible area according to the frequency band, antenna length, or mounting position. The advantages and disadvantages of resolution, maximum distance, or visible area are described below.

[0088] First, the higher the frequency band (for example, X band, etc.), the higher the range resolution and azimuth resolution, but the shorter the maximum distance according to the amount of water vapor. On the other hand, the lower the frequency band (for example, S band, etc.), the longer the maximum distance according to the amount of water vapor, but the lower the range resolution and azimuth resolution.

[0089] Next, the longer the antenna length, the higher the azimuth resolution, but the lower the rotation speed of the antenna. And the lower the rotation speed of the antenna, the lower the update frequency of the radar image, but the higher the number of hits per target (the number of radar irradiations). On the other hand, the shorter the antenna length, the lower the azimuth resolution, but the higher the rotation speed of the antenna. And the higher the rotation speed of the antenna, the higher the update frequency of the radar image, but the lower the number of hits per target (the number of radar irradiations).

[0090] Next, if the installation position is not blocked by a mast or the like, target signals can be displayed in all directions. On the other hand, if the installation position is blocked by a mast or the like, target signals are not displayed in the blocked azimuth. However, even in the blocked azimuth, diffraction can occur at long distances, so although specular reflection or multipath occurs, target signals can be displayed.

[0091] The radar image comparison unit 4 determines whether there is a target signal that is not displayed (including small boats, yachts, falling objects, etc.) in the radar image after extraction of a certain target signal among the radar images after extraction of each target signal input from the plurality of target signal extraction units 1-1 and 1-2, which is different from the radar image after extraction of other target signals (step S23).

[0092] And when there is a target signal that is not displayed (step S24, YES), the radar image comparison unit 4 feedback-controls the suppression parameter of both or one of the sea clutter and rain clutter so that the target signal that is not displayed is displayed again in the radar image after extraction of a certain target signal (step S25), and returns to step S23.

[0093] Here, the radar image comparison unit 4 feedback-controls the suppression parameter of both or one of the sea clutter and rain clutter so that in the radar image after a certain target signal is extracted, the suppression of both or one of the sea clutter and rain clutter is weakened, and the non-displayed target signal is displayed again (step S25).

[0094] On the other hand, when there is no non-displayed target signal (step S24, NO), the radar image comparison unit 4 finishes the feedback control of the suppression parameter of both or one of the sea clutter and rain clutter in both the radar image after a certain target signal is extracted and the radar image after another target signal is extracted, and proceeds to step S26.

[0095] In the left column of FIG. 9, six target signals are displayed in the radar image after the target signal in the S band or X band is extracted. In the middle column of FIG. 9, four target signals are displayed in the radar image after the target signal in the X band or S band is extracted. In the middle column of FIG. 9, two target signals are not displayed due to the disadvantage of resolution or maximum distance compared with the left column of FIG. 9.

[0096] In the right column of FIG. 9, in the radar image after the suppression parameter control of the X band or S band, the suppression parameter of the clutter becomes small and the suppression of the clutter is weakened, so some clutter is displayed, but the two target signals that were not displayed are displayed again. That is, regarding the resolution or the maximum distance, one disadvantage is compensated by the other advantage.

[0097] In the left column of FIG. 10, six target signals are displayed in the radar image after the target signal of the radar without obstacles is extracted. In the middle column of FIG. 10, five target signals are displayed in the radar image after the target signal of the radar with obstacles is extracted. In the middle column of FIG. 10, one target signal is not displayed due to the disadvantage of the visible area compared with the left column of FIG. 10.

[0098] In the right column of FIG. 10, in the radar image after the suppression parameter control of the radar with a shield, the clutter suppression parameter becomes smaller and the clutter suppression is weakened. Therefore, some clutter is displayed, but one target signal that was not displayed is displayed again. That is, for the visible area, if it is far away, one shortcoming is compensated by the other's advantage.

[0099] The radar image comparison unit 4 causes the radar image after each target signal extraction (after coordinate transformation, after coordinate rotation, after range adjustment, etc., and after radar image comparison and after re-control of the suppression parameter) to be displayed on the radar image display device D (step S26).

[0100] In this way, when using a radar image or a sonar image and making a navigation judgment by a crew member or the like, it is possible to determine whether to appropriately emphasize a target signal of a ship or the like regardless of the frequency band, antenna length, or mounting position. And when it is determined that the target signal of a ship or the like is not appropriately emphasized, the target signal of a ship or the like can be displayed again. Further, when it is determined that the target signal of a ship or the like is not appropriately emphasized because the clutter is overly suppressed, the target signal of a ship or the like can be displayed again.

[0101] As a modification, the radar image comparison unit 4 may feedback-control the suppression parameter of both or one of the wave clutter and the rain and snow clutter so that the target signal that is not displayed is displayed again when the suppression of both or one of the wave clutter and the rain and snow clutter is "strengthened" in the radar image after a certain target signal extraction.

[0102] (Procedure of radar image comparison process after clutter extraction of the present disclosure) The procedure of the radar image comparison process after clutter extraction according to the present disclosure is shown in FIG. 11. Specific examples of the radar image comparison process after clutter extraction according to the present disclosure are shown in FIGS. 12 and 13. The radar signal processing apparatus S acquires radar images before clutter suppression from a plurality of radar transceiver apparatuses A-1 and A-2 having the same or different frequency bands or antenna lengths (the mounting positions are necessarily different) (step S31). The clutter suppression units 2-1 and 2-2 and the clutter extraction units 3-1 and 3-2 execute clutter suppression and extraction processes (steps S11 to S19), respectively, on the radar images before clutter suppression (step S32).

[0103] Here, the plurality of radar transceiver apparatuses A-1 and A-2 complement each other's disadvantages in terms of resolution, maximum distance, or visible area according to the frequency band, antenna length, or mounting position. The advantages and disadvantages of the resolution, maximum distance, or visible area will be described below.

[0104] First, the higher the frequency band (for example, X-band, etc.), the higher the range resolution and azimuth resolution, but the shorter the maximum distance according to the amount of water vapor. On the other hand, the lower the frequency band (for example, S-band, etc.), the longer the maximum distance according to the amount of water vapor, but the lower the range resolution and azimuth resolution.

[0105] Next, the longer the antenna length, the higher the azimuth resolution, but the lower the rotation speed of the antenna. And the lower the rotation speed of the antenna, the lower the update frequency of the radar image, but the higher the number of hits per target (the number of radar irradiations). On the other hand, the shorter the antenna length, the lower the azimuth resolution, but the higher the rotation speed of the antenna. And the higher the rotation speed of the antenna, the higher the update frequency of the radar image, but the lower the number of hits per target (the number of radar irradiations).

[0106] Next, if the installation position is not blocked by a mast or the like, clutter can be displayed in all directions. On the other hand, if the installation position is blocked by a mast or the like, clutter is not displayed in the blocked direction. However, even in the blocked direction, diffraction can occur at a long distance, so although specular reflection or multipath occurs, clutter can be displayed.

[0107] The radar image comparison unit 4 determines whether there are more displayed clutters in a radar image after a certain clutter extraction among the radar images after clutter extraction input from the plurality of clutter extraction units 3-1 and 3-2 compared to the radar images after other clutter extractions (step S33).

[0108] Then, when there are more displayed clutters (step S34, YES), the radar image comparison unit 4 feedback-controls the suppression parameters of both or one of the sea clutter and the rain / snow clutter so that the displayed clutter is further displayed in the radar image after a certain clutter extraction (step S35), and proceeds to step S36.

[0109] Here, the radar image comparison unit 4 feedback-controls the suppression parameters of both or one of the sea clutter and the rain / snow clutter so that the displayed clutter is further displayed by strengthening the suppression of both or one of the sea clutter and the rain / snow clutter in the radar image after a certain clutter extraction (step S35). For example, the suppression parameters of both or one of the sea clutter and the rain / snow clutter may be feedback-controlled based on both or one of the sea information and the rain / snow information.

[0110] On the other hand, when there are not more displayed clutters (step S34, NO), the radar image comparison unit 4 terminates the feedback control of the suppression parameters of both or one of the sea clutter and the rain / snow clutter in both the radar image after a certain clutter extraction and the radar images after other clutter extractions, and proceeds to step S36.

[0111] In the left column of FIG. 12, in the radar image after clutter extraction in the S band or X band, there are fewer displayed clutters. In the middle column of FIG. 12, in the radar image after clutter extraction in the X band or S band, there are more displayed clutters. In the middle column of FIG. 12, compared with the left column of FIG. 12, due to the advantages of resolution or maximum distance, there are more displayed clutters (the clutter intensity is high and the clutter distribution is wide).

[0112] In the right column of FIG. 12, in the radar image after suppression parameter control in the X band or S band, the suppression parameter of the clutter becomes large and the suppression of the clutter is strengthened, so the displayed clutter is further displayed (the clutter intensity is even higher and the clutter distribution is even wider). That is, for the resolution or maximum distance, one of the advantages is further strengthened.

[0113] In the left column of FIG. 13, in the radar image after clutter extraction of the radar with obstacles, the displayed clutter does not exist in the shielding direction. In the middle column of FIG. 13, in the radar image after clutter extraction of the radar without obstacles, there are more displayed clutters. In the middle column of FIG. 13, compared with the left column of FIG. 13, due to the advantages of the visible area, there are more displayed clutters (the clutter intensity is high and the clutter distribution is wide).

[0114] In the right column of FIG. 13, in the radar image after suppression parameter control of the radar without obstacles, the suppression parameter of the clutter becomes large and the suppression of the clutter is strengthened, so the displayed clutter is further displayed (the clutter intensity is even higher and the clutter distribution is even wider). That is, for the visible area, one of the advantages is further strengthened.

[0115] The radar image comparison unit 4 causes the radar image after each clutter extraction (after coordinate conversion, coordinate rotation, range adjustment, etc. And after radar image comparison and re-control of suppression parameters.) to be displayed on the radar image display device D (step S36). Here, only the radar image after clutter extraction in which the advantages of the radar are further enhanced may be displayed.

[0116] As described above, when performing autonomous navigation of a ship or the like using a radar image or a sonar image, it is possible to determine whether clutter such as waves or rain and snow is appropriately included regardless of the frequency band, antenna length, or mounting position. And when it is determined that the clutter is appropriately included, the clutter can be further displayed. Further, if the clutter is further suppressed by any of the clutter suppression units, the clutter can be further displayed when it is determined that the clutter can be appropriately included by any of the clutter extraction units.

[0117] (Specific example of the autonomous navigation process of the present disclosure) A specific example of the autonomous navigation process of the present disclosure is shown in FIG. 14. The radar image display device D separately displays the radar image after target signal extraction output by the radar signal processing device S and the radar image after clutter extraction output by the radar signal processing device S (steps S5, S20, S26, S36). Here, only the radar image after clutter extraction in which the advantages of the radar are further enhanced may be displayed. The autonomous navigation device N performs autonomous navigation using the radar image after target signal extraction output by the radar signal processing device S and the radar image after clutter extraction output by the radar signal processing device S. Here, autonomous navigation may be performed only with the radar image after clutter extraction in which the advantages of the radar are further enhanced.

[0118] In the left column of FIG. 14, in the radar image after target signal extraction, the land signal is not buried in the sea clutter and rain / snow clutter, and the target signals (including small boats, yachts, and falling objects, etc.) are also not buried in the sea clutter and rain / snow clutter. In the middle column of FIG. 14, in the radar image after sea clutter separation and extraction, the sea clutter is extracted (the land signal may also be displayed, and the sea wave information may also be superimposed). In the right column of FIG. 14, in the radar image after rain / snow clutter separation and extraction, the rain / snow clutter is extracted (the land signal may also be displayed, and the rain / snow information may also be superimposed).

[0119] And, after confirming the destination of the ship or the like, the autonomous navigation device N performs autonomous navigation in the directions where the target signals and land signals are not displayed and where the sea clutter and rain / snow clutter are not displayed using the radar image. That is, after confirming the destination of the ship or the like, the autonomous navigation device N performs autonomous navigation so as to avoid obstacles such as ships and land and so as to avoid bad weather such as sea waves and rain / snow using the radar image.

Industrial Applicability

[0120] The radar signal processing device and the radar signal processing program of the present disclosure can automatically adjust the control method of the clutter suppression parameter both when performing autonomous navigation of a ship or the like using a radar image or a sonar image and when passing through the navigation judgment of a crew member or the like.

[0121] And, the radar signal processing device and the radar signal processing program of the present disclosure can determine whether to appropriately include clutter such as sea waves or rain / snow regardless of the frequency band, antenna length, or mounting position when performing autonomous navigation of a ship or the like using a radar image or a sonar image.

[0122] Moreover, the radar signal processing apparatus and the radar signal processing program of the present disclosure can determine whether to appropriately emphasize a target signal of a ship or the like regardless of the frequency band, antenna length, or mounting position when making a navigation decision by a crew member or the like using a radar image or a sonar image.

[0123] The radar image display device of the present disclosure can automatically display a radar image that is required both when performing autonomous navigation of a ship or the like and when making a navigation decision by a crew member or the like using a radar image or a sonar image. The autonomous navigation device of the present disclosure can perform autonomous navigation of a ship or the like using the radar image or sonar image output in this way.

Explanation of Signs

[0124] R: Radar system A, A-1, A-2: Radar transceiver T: Target information acquisition device M: Weather information acquisition device S: Radar signal processing device D: Radar image display device N: Autonomous navigation device 1, 1-1, 1-2: Target signal extraction unit 2, 2-1, 2-2: Clutter suppression unit 3, 3-1, 3-2: Clutter extraction unit 4: Radar image comparison unit

Claims

1. a clutter suppression unit which suppresses either or both of ocean wave clutter and rain / snow clutter from a radar image before clutter suppression based on either or both of ocean wave information and rain / snow information acquired from an external source, and outputs the clutter-suppressed radar image; a clutter extraction unit that subtracts the clutter-suppressed radar image from the pre-clutter-suppressed radar image to extract both or one of the ocean wave clutter and the rain / snow clutter, and outputs the radar image after clutter extraction; A radar signal processing device comprising:

2. The clutter extraction unit extracts the wave clutter separately from the rain / snow clutter based on a suppression parameter of the wave clutter for the radar image after the clutter extraction, or extracts the rain / snow clutter separately from the wave clutter based on a suppression parameter of the rain / snow clutter for the radar image after the clutter extraction.

2. The radar signal processing device according to claim 1 .

3. The clutter suppression unit feedback controls suppression parameters of both or one of the ocean wave clutter and the rain / snow clutter based on a degree of agreement between the radar image after the clutter extraction (current or past radar image) and both or one of the ocean wave information and the rain / snow information (the current or past information).

2. The radar signal processing device according to claim 1 .

4. the clutter suppression unit and the clutter extraction unit respectively perform clutter suppression processing and clutter extraction processing on the radar images before clutter suppression acquired from a plurality of radar transceivers having the same or different frequency bands or antenna lengths; a radar image comparison unit which, when a certain radar image after clutter extraction contains more clutter to be displayed than other radar images after clutter extraction, feedback controls suppression parameters of both or one of the ocean wave clutter and the rain / snow clutter so that the certain radar image after clutter extraction further displays the clutter when the certain radar image after clutter extraction contains more clutter to be displayed than other radar images after clutter extraction; The radar signal processing device according to claim 1 , further comprising:

5. The radar image comparison unit feedback controls suppression parameters of both or one of the ocean wave clutter and the rain / snow clutter so that the suppression of both or one of the ocean wave clutter and the rain / snow clutter is strengthened in the radar image after the clutter is extracted, thereby making the displayed clutter more visible.

5. The radar signal processing device according to claim 4.

6. a target signal extraction unit which extracts both or one of a target signal and a land signal from the radar image before clutter suppression based on both or one of target information and land information acquired from an external source, suppresses both or one of the ocean wave clutter and the rain / snow clutter, and outputs the radar image after target signal extraction; The radar signal processing device according to claim 1 , further comprising:

7. The target signal extraction unit feedback controls suppression parameters of both or one of the ocean wave clutter and the rain / snow clutter based on a degree of coincidence between a radar image (current or past radar image) after the target signal extraction and both or one of the target information and the land information (the current or past information).

7. The radar signal processing device according to claim 6.

8. The clutter suppression unit feedback controls suppression parameters of both or one of the ocean wave clutter and the rain / snow clutter based on a degree of match between the radar image after the clutter suppression and the radar image after the target signal extraction.

7. The radar signal processing device according to claim 6.

9. the target signal extraction unit performs a target signal extraction process on each of the radar images before clutter suppression acquired from a plurality of radar transceivers having the same or different frequency bands or antenna lengths; a radar image comparison unit that feedback-controls suppression parameters of both or one of the ocean wave clutter and the rain / snow clutter so that, when a target signal that is not displayed in a certain radar image after the target signal extraction is present in the radar images after the target signal extraction, unlike the other radar images after the target signal extraction, the target signal that is not displayed in the certain radar image after the target signal extraction is displayed again in the certain radar image after the target signal extraction; The radar signal processing device according to claim 6, further comprising:

10. The radar image comparison unit feedback controls suppression parameters of both or one of the ocean wave clutter and the rain / snow clutter so that the target signal that is not displayed is displayed again by weakening suppression of both or one of the ocean wave clutter and the rain / snow clutter in the radar image after extraction of the certain target signal.

10. The radar signal processing device according to claim 9.

11. A radar signal processing program for causing a computer to execute each processing step executed by each processing unit included in the radar signal processing device according to any one of claims 1 to 10.

12. 11. A radar image display device that separately displays a radar image after the clutter extraction output by the radar signal processing device according to claim 1 and a radar image after the target signal extraction output by the radar signal processing device according to claim 6.

13. 11. An autonomous navigation device that performs autonomous navigation using a radar image after clutter extraction output by the radar signal processing device according to claim 1 and a radar image after target signal extraction output by the radar signal processing device according to claim 6.

Images