Navigation control system, navigation control method, and program for unmanned vessels.

Abstract

This invention relates to a navigation control technology that evaluates the external monitoring performance in response to fluctuations in the energy state or communication state of an unmanned vessel and controls the speed limit based on said external monitoring performance. [Solution] In this invention, an index representing monitoring capability is calculated based on the power supply status and communication quality related to the sensor, and the speed limit is changed in stages or continuously in accordance with the decrease in this index. Furthermore, speed control is performed taking into account the relationship between detection distance and stopping distance, and the monitoring capability after changing the sensor's operating mode. In addition, when multiple unmanned vessels are navigating in cooperation, the speed limit is set considering the monitoring capability of each vessel or their complementary relationship. This enables safe navigation control that is adapted to fluctuations in monitoring performance.

Description

Technical Field

[0004] ,

[0001] The present invention relates to a navigation control technology for an unmanned boat that is an autonomous navigation ship or a remotely operated ship. More specifically, the present invention evaluates the external monitoring performance according to fluctuations in the energy state or communication state of one or more sensors mounted on the unmanned boat, and controls the speed limit of the unmanned boat based on the external monitoring performance. The present invention relates to a navigation control system, a navigation system, a navigation control method, and a program. The present invention can be applied not only to a single unmanned boat but also to a navigation system in which a plurality of unmanned boats cooperate with each other while sharing monitoring information.

Background Art

[0002] In an unmanned boat that is an autonomous navigation ship or a remotely operated ship, an object outside the boat, other ships, floating objects, a shore wall, and the route situation are monitored by a visible camera, an infrared camera, a radar, a lidar, and other sensors, and steering judgment and speed control are performed based on the results. In such an unmanned boat, it is required to maintain a continuous lookout in accordance with relevant collision avoidance rules and navigate at a safe speed appropriate to the situation. On the other hand, in an unmanned boat, it may be difficult to keep each mounted sensor operating at maximum performance at all times due to a decrease in the remaining battery level, a limitation in power generation capacity, a decrease in the communication bandwidth, an increase in communication delay, an increase in processing load, and the like.

[0003] Conventionally, technologies for changing the resolution, frame rate, transmission data volume, etc. of sensors according to energy constraints or communication constraints, and technologies for controlling the speed of a moving body based on the relationship between the detection distance and the stopping distance have been proposed. In addition, when a plurality of unmanned boats navigate in cooperation, a decrease in the sensor performance of one unmanned boat may also affect the monitoring ability of other unmanned boats. Therefore, it may be difficult to ensure the operation reliability of the entire group only by control on the premise of a single boat.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] The present invention aims to provide a navigation control system, navigation system, navigation control method, and program that can achieve both continued lookout and speed control by controlling the speed limit according to the external monitoring performance maintained at that time, even when the energy state or communication state of an unmanned vessel deteriorates. [Means for solving the problem]

[0006] To solve the above problems, a navigation control system according to one aspect of the present invention is a navigation control system installed on a single unmanned vessel which is an autonomous vessel or a remotely operated vessel, comprising: a state acquisition unit that acquires the energy state or communication state of one or more sensors provided on the unmanned vessel; and a ship speed control unit that sets an upper speed limit of the unmanned vessel based on the external monitoring performance of the one or more sensors corresponding to the energy state or the communication state, and lowers the upper speed limit when the external monitoring performance deteriorates.

[0007] The external monitoring performance is represented, for example, by indicators representing the detection distance, identifiable distance, field of view, update cycle, resolution, and other monitoring capabilities of the target. The communication status includes, for example, indicators representing the available bandwidth, communication delay, processing delay, packet loss, and other communication quality. The unmanned vessel may further include a sensor control unit that changes the operating mode of one or more sensors according to the energy status or the communication status, in which case the ship speed control unit sets the speed limit based on the external monitoring performance according to the changed operating mode.

[0008] The change in the operating mode may include at least one change from the resolution, frame rate, sampling period, field of view, amount of transmitted data, and transmission method. The ship speed control unit may gradually reduce the speed limit in accordance with the decrease in the external monitoring performance. The ship speed control unit may also set the speed limit based on the detection distance based on the external monitoring performance and the stopping distance or the distance required for avoidance of the unmanned vessel. Furthermore, if the energy state or the communication state deteriorates, the ship speed control unit may leave one or more sensors with a high operational priority as the target of operation and set the speed limit based on the external monitoring performance of the sensor left as the target of operation.

[0009] Another aspect of the present invention relates to a navigation system including a plurality of unmanned vessels, comprising: a state acquisition unit that acquires the energy state or communication state of one or more sensors provided by each of the plurality of unmanned vessels; and a speed control unit that sets a speed limit for at least one of the plurality of unmanned vessels based on the external monitoring performance of the sensor corresponding to the energy state or communication state of at least one of the plurality of unmanned vessels, and reduces the speed limit when the external monitoring performance deteriorates.

[0010] In this navigation system, if at least part of the surrounding monitoring of the first unmanned vessel depends on the sensors of the second unmanned vessel, the speed limit of the first unmanned vessel may be set based on the external monitoring performance of the second unmanned vessel. Alternatively, the speed limit of at least some of the unmanned vessels may be set based on the unmanned vessel with the lowest external monitoring performance among the plurality of unmanned vessels. Furthermore, if the overall external monitoring performance of the plurality of unmanned vessels deteriorates due to a deterioration in the energy state or communication state of at least one of the plurality of unmanned vessels, the speed limit of each unmanned vessel may be set to increase the distance between the plurality of unmanned vessels.

[0011] Furthermore, when the multiple unmanned vessels are sailing in formation, the speed limit may be set considering the monitoring range of the sensors of the preceding or accompanying unmanned vessel. Also, when sensor data acquired by at least one of the multiple unmanned vessels is used to supplement the surrounding monitoring of the other unmanned vessels, the speed limit of the other unmanned vessels may be set based on the external monitoring performance of the sensors used for such supplementation. Moreover, when the energy state or communication state of the multiple unmanned vessels improves and the overall external monitoring performance of the multiple unmanned vessels is restored, the speed limit may be increased based on the restored external monitoring performance.

[0012] Furthermore, if the transmission format of sensor data is changed to image data, region extraction data, feature data, or metadata in response to a deterioration in the communication status of at least one of the multiple unmanned vessels, the speed limit may be set based on the external monitoring performance corresponding to the changed transmission format. A navigation control method according to yet another aspect of the present invention includes steps corresponding to each of the above configurations. A program according to yet another aspect of the present invention is a program that causes a computer to execute processing corresponding to each of the above configurations. [Effects of the Invention]

[0013] According to the present invention, even if the energy state or communication state of an unmanned vessel deteriorates, the speed limit can be controlled according to the external monitoring performance maintained at that time. This prevents the maintenance of high speeds despite reduced sensor performance, enabling a balance between continued lookout and speed control. Furthermore, even when the sensor operating mode, transmission method, or priority sensor selection is involved, the system can transition to speed control according to the changed monitoring capability, thereby improving operational reliability under energy or communication constraints. Moreover, even when multiple unmanned vessels are operating in coordination, the deterioration of the external monitoring performance of one unmanned vessel can be reflected in the speed control of the entire group, thereby improving the control reliability of the entire navigation system that utilizes monitoring enhancement. [Brief explanation of the drawing]

[0014] [Figure 1] This is a block diagram showing the overall configuration of the navigation control system 10 according to the first embodiment. It shows the interconnection relationships of the sensor 50, state acquisition unit 20, ship speed control unit 30, communication unit 25, processor 27, memory unit 26, and propulsion device 80 mounted on a single unmanned vessel 60. [Figure 2] This graph shows an example of the relationship between external monitoring performance and speed limits. The horizontal axis represents the index value of external monitoring performance, and the vertical axis represents the speed limit. It shows the gradual transition to the first speed limit, second speed limit, and stop command corresponding to the first threshold, second threshold, and third threshold. [Figure 3] This is an explanatory diagram illustrating the concept of setting a speed limit based on the relationship between detection distance and stopping distance. It schematically shows the relationship between detection distance, stopping distance, and safety margin distance in front of the unmanned vessel 60. [Figure 4] This is an explanatory diagram illustrating the concept of priority sensor selection. It shows the arrangement of the forward camera 50a, forward radar 50b, rear camera 50c, and side auxiliary sensors 50d mounted on the unmanned vessel 60, and how the target of operation is selected based on priority when the energy state or communication state deteriorates. [Figure 5] This flowchart shows the flow of navigation control processing in a single unmanned vessel 60 according to the first embodiment. It illustrates the processing procedure from acquiring the energy state or communication state (step S1) to setting the speed limit and controlling the cruising speed. [Figure 6] This is a block diagram showing the overall configuration of the navigation control system 10 according to the second embodiment. It shows a configuration in which a sensor control unit 40 is added to the configuration of the first embodiment, and shows the signal flow from the state acquisition unit 20 to the sensor control unit 40 and the ship speed control unit 30. [Figure 7] This is a flowchart showing the flow of the navigation control process according to the second embodiment. It shows the processing procedure including the change of the operating mode by the sensor control unit 40 (step S102). [Figure 8]It is a block diagram showing the overall configuration of a navigation system 70 including a plurality of unmanned boats 60 according to the third embodiment. It shows the connection relationship between the first unmanned boat 60A, the second unmanned boat 60B, the control device 90, and the communication unit 91 of the control device 90. [Figure 9] It is an explanatory diagram showing the concept of monitoring complementation and transmission form change among a plurality of unmanned boats. It shows how the sensor 50 of the second unmanned boat 60B complementarily monitors the blind spot direction of the first unmanned boat 60A, and how the transmission form is changed from image data to region extraction data, feature amount data, or metadata in response to a decrease in the communication state. [Figure 10] It is a flowchart showing the flow of navigation control processing in a navigation system 70 including a plurality of unmanned boats 60 according to the third embodiment. It shows the processing procedure from the state acquisition of each unmanned boat 60 to the adjustment of the speed upper limit of the whole group.

Embodiments for Carrying out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that each of the following embodiments shows an example of the present invention, and the present invention is not limited to the following embodiments. Also, the components of each of the following embodiments can be combined as appropriate. Furthermore, in each drawing, the same or corresponding components are denoted by the same reference numerals, and redundant explanations are omitted as appropriate.

[0016] (First Embodiment) FIG. 1 is a block diagram showing the overall configuration of a navigation control system 10 according to the first embodiment. The navigation control system 10 according to the first embodiment is mounted on a single unmanned boat 60 that is an autonomous operation ship or a remotely operated ship. The unmanned boat 60 includes one or more sensors 50 for peripheral monitoring, a navigation control system 10, and a propulsion device 80. The navigation control system 10 includes a state acquisition unit 20, a ship speed control unit 30, a communication unit 25, a processor 27, and a storage unit 26. The ship speed control unit 30 outputs a speed command to the propulsion device 80, and the propulsion device 80 controls the navigation speed of the unmanned boat 60 based on the speed command.

[0017] The processor 27 may be any of a CPU, GPU, FPGA, or ASIC, and realizes the functions of the state acquisition unit 20 and the vessel speed control unit 30 by executing the program stored in the storage unit 26. The storage unit 26 is a storage device such as a ROM, RAM, flash memory, or SSD, and stores the program executed by the processor 27 and various setting parameters. The communication unit 25 is a communication interface for performing wireless communication with an onshore control station or other unmanned vessels, and uses communication means such as satellite communication, long-distance wireless communication, or a mesh network. The communication unit 25 also functions as a provider of communication quality information when the state acquisition unit 20 acquires the communication state.

[0018] The sensor 50 is a device mounted for monitoring the outside of the unmanned vessel 60, and is constituted by, for example, a visible camera, an infrared camera, a radar, or a lidar. The unmanned vessel 60 may be equipped with only a single type of sensor 50, or may be equipped with a combination of a plurality of types of sensors 50. The sensor 50 may be arranged in each of the bow direction, the left side direction, the right side direction, and the stern direction of the unmanned vessel 60, and is preferably arranged at least in the bow direction. When a plurality of sensors 50 are mounted, they can be distinguished as a front camera 50a, a front radar 50b, a rear side camera 50c, and a side auxiliary sensor 50d. The monitoring data acquired by each sensor 50 serves as an evaluation basis for the external monitoring performance referred to when setting the speed limit in the vessel speed control unit 30 described later.

[0019] The propulsion device 80 is a device for propelling the unmanned vessel 60, and is constituted by, for example, a propeller propulsion device, a water jet propulsion device, or an electric propulsion device. The propulsion device 80 adjusts the rotation speed or output based on the speed command output from the vessel speed control unit 30, and controls the navigation speed of the unmanned vessel 60. The type of the propulsion device 80 is not limited, and is appropriately selected according to the use and size of the unmanned vessel 60.

[0020] The status acquisition unit 20 is a functional unit that acquires the energy status or communication status related to the sensor 50. Examples of energy statuses include the remaining battery charge available to the sensor 50, the maximum power limit that can be allocated to the sensor 50, the power distribution status with auxiliary equipment, the output margin of the generator, and the amount of power generated by auxiliary power sources such as solar panels. Examples of communication statuses include the available bandwidth between the unmanned vessel and a land-based control station or other unmanned vessel via the communication unit 25, communication delay, processing delay, packet loss, number of retransmissions, and transmission waiting time. The status acquisition unit 20 repeatedly acquires these status quantities at predetermined intervals and provides them to the ship speed control unit 30. The acquisition interval is preferably set according to the cruising speed of the unmanned vessel 60 and the rate of change of the surrounding environment.

[0021] The ship speed control unit 30 is a functional unit that sets the speed limit of the unmanned vessel 60 based on the external monitoring performance of the sensor 50 according to the energy state or communication state acquired by the state acquisition unit 20. Here, external monitoring performance is a concept that represents the ability to monitor the outside of the unmanned vessel 60, and is represented by at least one of the following: detection distance, identifiable distance, field of view, update cycle, and resolution. Detection distance refers to the maximum distance at which the sensor 50 can detect the presence of a target, and identifiable distance refers to the maximum distance at which the sensor 50 can identify the type or shape of a target. Field of view refers to the range of azimuth or elevation angles that the sensor 50 can monitor simultaneously, and update cycle refers to the time interval at which the sensor 50 updates the monitoring data.

[0022] External monitoring performance fluctuates depending on the energy state or communication state. For example, if the battery level decreases and the power supplied to the sensor 50 is limited, the resolution or frame rate of the sensor 50 decreases, resulting in a shorter detection range or identifiable range. Also, if the communication bandwidth via the communication unit 25 decreases, the amount of data transmitted by the sensor 50 is limited, and the update cycle in remote monitoring is extended. The ship speed control unit 30 sets a speed limit based on these fluctuations in external monitoring performance.

[0023] The ship speed control unit 30 reduces the speed limit if the external monitoring performance deteriorates. Therefore, even if the monitoring capability of the sensor 50 decreases due to a decrease in battery level or a deterioration in communication quality, the ship can transition to a speed commensurate with the reduced capability. This configuration makes it possible to control the speed while continuing the lookout, ensuring safe navigation at a safe speed. The reduction in the speed limit may be performed immediately when a decrease in external monitoring performance is detected, or it may be performed after a predetermined delay period. The ship speed control unit 30 outputs the set speed limit as a speed command to the propulsion system 80.

[0024] The ship speed control unit 30 may gradually lower the speed limit in accordance with the decrease in external monitoring performance. Figure 2 is a graph showing an example of the correspondence between external monitoring performance and the speed limit. For example, if the external monitoring performance falls below the first threshold, the ship may move to a first speed limit lower than the normal cruising speed; if it falls below the second threshold, it may move to an even lower second speed limit; and if it falls below the third threshold, it may move to a stop command or a slow-speed command. In this way, by setting multiple thresholds and corresponding speed limits for external monitoring performance, speed control that gradually follows the decrease in the capacity of the sensor 50 can be realized. Note that the number of thresholds and speed limits is not limited to the example above; there may be two stages, or four or more stages. Alternatively, instead of steps, the speed limit may be associated with an index value of external monitoring performance using a continuous function.

[0025] Furthermore, the ship speed control unit 30 may set a speed limit based on the detection distance based on the external monitoring performance and the stopping distance or the distance required for avoidance by the unmanned vessel 60. Figure 3 is an explanatory diagram illustrating the concept of this relationship. Let Dd be the detection distance of the forward monitoring sensor, Ds be the distance required for the unmanned vessel 60 to stop from its current speed, Da be the distance required to avoid a collision after starting evasive maneuvers, and α be the safety margin distance. The ship speed control unit 30 sets the speed limit to such that Dd ≥ Ds + α or Dd ≥ Da + α. If the detection distance Dd of the forward monitoring sensor becomes shorter due to a decrease in energy state or communication state, the speed limit is lowered to satisfy the above inequality. This makes it possible to suppress delays in hazard recognition and the initiation of evasive action even after a decrease in monitoring performance.

[0026] Furthermore, if the energy state or communication state deteriorates, the ship speed control unit 30 may keep the sensor 50 with the highest operational priority among the multiple sensors 50 as the target for operation, and set a speed limit based on the external monitoring performance of the sensor that remains as the target for operation. Figure 4 is an explanatory diagram illustrating the concept of priority sensor selection. For example, the forward camera 50a and forward radar 50b that monitor the direction of travel may be designated as priority sensors, and the resolution or update cycle of the rear camera 50c or side auxiliary sensor 50d may be reduced first. In this case, the ship speed control unit 30 sets a speed limit based on the external monitoring performance of the forward camera 50a and forward radar 50b that remain as the target for operation. Therefore, while prioritizing the allocation of limited power or communication resources to forward monitoring, the cruising speed can be appropriately suppressed according to the remaining monitoring capacity.

[0027] Next, with reference to Figure 5, the flow of navigation control processing in a single unmanned vessel 60 according to the first embodiment will be described. Figure 5 is a flowchart of the navigation control processing. Each step in this flowchart is realized by the processor 27 of the navigation control system 10 executing a program stored in the memory unit 26.

[0028] In step S1, the status acquisition unit 20 acquires the energy status or communication status of one or more sensors 50 equipped on the unmanned vessel 60. Specifically, it acquires status quantities such as battery level, maximum allocatable power limit, available communication bandwidth via the communication unit 25, communication delay amount, and packet loss rate. This acquisition process is repeatedly executed at predetermined intervals.

[0029] In step S2, the ship speed control unit 30 evaluates the external monitoring performance of each sensor 50 based on the energy state or communication state acquired in step S1. The evaluation of external monitoring performance is performed using at least one of the following as an indicator: detection distance, identifiable distance, field of view, update cycle, and resolution. If multiple sensors 50 are installed, the external monitoring performance of each sensor 50 may be evaluated individually, and the overall external monitoring performance may be calculated.

[0030] In step S3, the ship speed control unit 30 determines whether the external monitoring performance evaluated in step S2 is above a predetermined threshold. If the external monitoring performance is above the predetermined threshold (Yes in step S3), the process proceeds to step S4; if the external monitoring performance falls below the predetermined threshold (No in step S3), the process proceeds to step S5. Here, the predetermined threshold may be set in multiple stages, such as the first threshold, second threshold, and third threshold mentioned above.

[0031] In step S4, the ship speed control unit 30 maintains the current speed limit. That is, as long as the external monitoring performance is sufficiently maintained, the speed limit will not be changed. The process then proceeds to step S7.

[0032] In step S5, the ship speed control unit 30 sets a speed limit according to the amount of decrease in external monitoring performance. As described above, if the external monitoring performance falls below the first threshold, the system switches to the first speed limit; if it falls below the second threshold, it switches to the second speed limit; and if it falls below the third threshold, it switches to a stop command or a slow-speed command. Alternatively, the speed limit may be calculated based on the relationship between the detection distance and the stopping distance.

[0033] In step S6, the ship speed control unit 30 outputs a speed command to the propulsion unit 80 based on the new speed limit set in step S5, and controls the cruising speed of the unmanned vessel 60 to be below the speed limit. The transition to the speed limit may be carried out gradually at a predetermined deceleration rate in order to suppress ship motion caused by rapid deceleration.

[0034] In step S7, the ship speed control unit 30 determines whether or not it is necessary to continue sailing. If sailing is to be continued (Yes in step S7), the process returns to step S1, and state acquisition and re-evaluation of external monitoring performance for the next cycle are performed. If sailing is to be terminated (No in step S7), the process in this flowchart is terminated. In this way, by repeatedly executing the processes from step S1 to step S7, continuous speed limit control that follows fluctuations in energy state or communication state is realized.

[0035] (Second Embodiment) Figure 6 is a block diagram showing the overall configuration of the navigation control system 10 according to the second embodiment. In the second embodiment, the unmanned vessel 60 further includes a sensor control unit 40 in addition to the configuration of the first embodiment (state acquisition unit 20, ship speed control unit 30, communication unit 25, processor 27, storage unit 26, sensor 50, and propulsion device 80). The sensor control unit 40 is a functional unit that changes the operating mode of the sensor 50 according to the energy state or communication state acquired by the state acquisition unit 20. The navigation control system 10 of the second embodiment is configured to include the state acquisition unit 20, ship speed control unit 30, and sensor control unit 40.

[0036] Changes to the operating mode performed by the sensor control unit 40 include reducing the resolution, reducing the frame rate, extending the sampling period, changing the field of view (such as switching to a narrow-angle mode), reducing the amount of transmitted data, and changing the transmission method. A change in the transmission method refers to, for example, changing from a method in which the image data acquired by the sensor 50 is transmitted as is, to a method in which region extraction data is transmitted, which is a portion of the image data, to a method in which only feature quantities extracted from the image data are transmitted, or to a method in which only metadata such as the position and type of the target is transmitted.

[0037] Specifically, the sensor control unit 40 operates in a first transmission mode, which transmits the image data acquired by the sensor 50 as is, when the communication status via the communication unit 25 is good (for example, when the available bandwidth is above the first bandwidth threshold). When the communication bandwidth decreases and the available bandwidth falls below the first bandwidth threshold, it switches to a second transmission mode, which transmits region extraction data in which the target region has been extracted. When the communication bandwidth further decreases and the available bandwidth falls below the second bandwidth threshold, it switches to a third transmission mode, which transmits feature data or metadata.

[0038] Similarly, the sensor control unit 40 may change the operating mode of the sensor 50 according to the energy state. For example, when the battery level falls below a first power threshold, the frame rate of the sensor 50 may be reduced; when it falls below a second power threshold, the resolution may be further reduced; and when it falls below a third power threshold, the operation of some of the sensors 50 may be stopped. The sensor control unit 40 may also change the operating mode by considering both the energy state and the communication state simultaneously.

[0039] The ship speed control unit 30 sets the speed limit based on the external monitoring performance of the sensor 50 after the operating mode has been changed by the sensor control unit 40. Specifically, if the sensor control unit 40 reduces the resolution, the speed limit is reset based on the detection distance or identifiable distance corresponding to the reduced resolution. Furthermore, if the transmission format is changed from image data to feature data or metadata, the speed limit is reset based on the external monitoring performance corresponding to the changed transmission format (for example, monitoring performance that reflects changes in target type identification accuracy or position estimation accuracy). In this way, power saving or reduction of communication volume by the sensor control unit 40 and speed limit adjustment by the ship speed control unit 30 are operated in a consistent manner.

[0040] Furthermore, the priority sensor selection described in the first embodiment can also be applied in the second embodiment. That is, when the energy state or communication state deteriorates, the sensor control unit 40 keeps the forward camera 50a and forward radar 50b, which have high operational priority, as targets for operation, and changes the operating mode of the rear camera 50c or side auxiliary sensor 50d first (for example, by reducing the frame rate, reducing the resolution, or stopping operation). The ship speed control unit 30 sets a speed limit based on the external monitoring performance of the priority sensors that remain as targets for operation.

[0041] Next, with reference to Figure 7, the flow of the navigation control process according to the second embodiment will be described. Figure 7 is a flowchart of the navigation control process. The flowchart of the second embodiment is the flowchart of the first embodiment (Figure 5) with the addition of a step for changing the operating mode by the sensor control unit 40.

[0042] In step S101, the state acquisition unit 20 acquires the energy state or communication state of one or more sensors 50 equipped on the unmanned vessel 60. This process is the same as in step S1 in Figure 5.

[0043] In step S102, the sensor control unit 40 determines whether it is necessary to change the operating mode of the sensor 50 based on the energy state or communication state acquired in step S101, and changes the operating mode if necessary. Specifically, it performs actions such as changing the transmission method in response to a decrease in communication bandwidth (changing from image data to region extraction data, feature data, or metadata), decreasing the frame rate or resolution in response to a decrease in battery level, or selecting a priority sensor. If it is not necessary to change the operating mode, the current operating mode is maintained.

[0044] In step S103, the ship speed control unit 30 evaluates the external monitoring performance of the sensor 50 after the change in the operating mode in step S102 (or the current operating mode if there is no change). This process corresponds to step S2 in Figure 5, but differs in that the evaluation reflects the change in the operating mode by the sensor control unit 40.

[0045] In step S104, the ship speed control unit 30 determines whether the external monitoring performance evaluated in step S103 is above a predetermined threshold. If the external monitoring performance is above the predetermined threshold (Yes in step S104), the process proceeds to step S105; if the external monitoring performance falls below the predetermined threshold (No in step S104), the process proceeds to step S106.

[0046] In step S105, the ship speed control unit 30 maintains the current speed limit. The process then proceeds to step S108.

[0047] In step S106, the ship speed control unit 30 sets a speed limit according to the amount of decrease in external monitoring performance. The gradual decrease, calculation based on the relationship between detection distance and stopping distance, etc., are the same as in the first embodiment.

[0048] In step S107, the ship speed control unit 30 outputs a speed command to the propulsion system 80 based on the new speed limit set in step S106, and controls the cruising speed.

[0049] In step S108, the ship speed control unit 30 determines whether or not it is necessary to continue sailing. If sailing is to be continued (Yes in step S108), the process returns to step S101. If sailing is to be terminated (No in step S108), the process in this flowchart is terminated.

[0050] (Third embodiment) Figure 8 is a block diagram showing the overall configuration of a navigation system 70 including a plurality of unmanned vessels 60 according to the third embodiment. The navigation system 70 is composed of a plurality of unmanned vessels 60 (hereinafter referred to as the first unmanned vessel 60A, the second unmanned vessel 60B, etc. when distinguishing between them) and a control device 90. Each unmanned vessel 60 is equipped with a state acquisition unit 20, a ship speed control unit 30, a communication unit 25, a processor 27, a storage unit 26, a sensor 50, a propulsion device 80, and a sensor control unit 40 as needed, as described in the first or second embodiment. The control device 90 is a computer installed on land or on a mother ship, which communicates with each unmanned vessel 60 via a communication unit 91 and aggregates information regarding the energy state, communication state, and external monitoring performance of each unmanned vessel 60.

[0051] In the navigation system 70, the energy status or communication status acquired by the status acquisition unit 20 of each unmanned vessel 60 may be mutually notified among the unmanned vessels 60 via the communication unit 25, or it may be transmitted to the control device 90 via the communication unit 91 of the control device 90 and aggregated by the control device 90. The functions of the speed control unit 30 may be distributed among the unmanned vessels 60, centrally provided in the control device 90, or a combination of these. In the following description, we will mainly describe a configuration in which each unmanned vessel 60 is equipped with a speed control unit 30 and the control device 90 aggregates information from each unmanned vessel 60 and transmits commands regarding speed limits to each unmanned vessel 60, but the present invention is not limited to this configuration.

[0052] Figure 9 is an explanatory diagram illustrating the concepts of monitoring complementarity and transmission mode modification between multiple unmanned vessels. In the third embodiment, at least a portion of the surrounding monitoring of the first unmanned vessel 60A may depend on the sensor 50 of the second unmanned vessel 60B. For example, the camera or radar of the second unmanned vessel 60B may complementarily monitor the blind spots to the side or diagonally forward of the first unmanned vessel 60A. In this case, if the energy state or communication state of the second unmanned vessel 60B deteriorates and the external monitoring performance of the sensor 50 used for complementary monitoring decreases, the ship speed control unit 30 or control device 90 will also lower the speed limit of the first unmanned vessel 60A. This ensures that even in operations that rely on monitoring complementarity from other vessels, a decrease in complementary capability is not overlooked and is reflected in speed control.

[0053] Furthermore, the navigation system 70 may set a speed limit for at least some of the unmanned vessels 60, using the unmanned vessel 60 with the lowest external monitoring performance as a reference. For example, when performing convoy navigation or group control, the unmanned vessel 60 with the worst communication status or the unmanned vessel 60 with the lowest battery level may be adopted as the reference vessel, and a speed limit for the entire group or a portion of the group may be set based on the external monitoring performance of that reference vessel. This allows for speed control that matches the lower limit of the monitoring capability of the entire group, thereby preventing some of the unmanned vessels 60 from falling into a state of insufficient monitoring.

[0054] Furthermore, in the navigation system 70, if the energy state or communication state of at least one of the multiple unmanned vessels 60 deteriorates, resulting in a decrease in the overall external monitoring performance of the multiple unmanned vessels 60, the speed limit of each unmanned vessel 60 may be set to increase the distance between the multiple unmanned vessels 60. For example, when the control device 90 detects a decrease in the overall external monitoring performance, it may send a command to increase the formation spacing along with a command to decrease the speed limit to each unmanned vessel 60 via the communication unit 91. This configuration makes it possible to suppress the frequency of interference between each unmanned vessel and maintain safe operation even when monitoring capabilities are reduced.

[0055] Furthermore, the navigation system 70 may set a speed limit for a following or adjacent boat when sailing in a convoy, taking into account the monitoring range of the sensors 50 of the preceding or adjacent unmanned boat 60. For example, the speed limit for the following boat may be kept relatively high while the rearward monitoring radar of the preceding boat is functioning normally, and the speed limit for the following boat may be lowered when the monitoring capability of the preceding boat deteriorates due to poor communication. This ensures that the speed limit for each unmanned boat 60 in the convoy is set to reflect not only the performance of its own sensors but also the monitoring support from other boats, thereby maintaining the safety of the entire convoy.

[0056] Furthermore, in the navigation system 70, when sensor data acquired by at least one of the multiple unmanned vessels 60 is used to supplement the surrounding monitoring of other unmanned vessels 60, the speed limit of the other unmanned vessels 60 may be set based on the external monitoring performance of the sensor used for the supplementation. As shown in Figure 9, if the transmission format of the sensor data used for supplementation is changed from image data to region extraction data, feature data, or metadata in response to a deterioration in communication status, the speed limit is set based on the external monitoring performance re-evaluated according to the changed transmission format. Therefore, even under conditions of reduced communication bandwidth, speed control commensurate with the remaining shared monitoring capability becomes possible.

[0057] Furthermore, the navigation system 70 increases the speed limit based on the recovered external monitoring performance when the energy state or communication state of multiple unmanned vessels 60 improves and the overall external monitoring performance of the multiple unmanned vessels 60 is restored. This allows for the restoration of operational efficiency when constraints are eased. The speed limit may be increased gradually, or after sufficient monitoring performance recovery has been continuously confirmed. Since a sudden increase in speed may create a speed difference with other unmanned vessels 60 in the formation, it is preferable to increase the speed limit of the entire group synchronously.

[0058] Next, with reference to Figure 10, the flow of navigation control processing in a navigation system 70 including a plurality of unmanned vessels 60 according to the third embodiment will be described. Figure 10 is a flowchart of the said navigation control processing.

[0059] In step S201, the status acquisition unit 20 of each unmanned vessel 60 acquires the energy state or communication state related to its own sensor 50 and transmits it to the control device 90 via the communication unit 25. The control device 90 aggregates the status quantities received from each unmanned vessel 60 via the communication unit 91.

[0060] In step S202, the control device 90 or the speed control unit 30 of each unmanned vessel 60 evaluates the external monitoring performance of the sensors 50 of each unmanned vessel 60 based on the energy state or communication state of each unmanned vessel 60 acquired in step S201. This evaluation is performed using at least one of the detection distance, identifiable distance, field of view, update cycle, and resolution described in the first embodiment as indicators.

[0061] In step S203, the control device 90 or the speed control unit 30 calculates the effective external monitoring performance for each unmanned vessel 60, taking into account the monitoring complementarity relationships among the multiple unmanned vessels 60. For example, if the sensor 50 of the second unmanned vessel 60B complements the blind spot of the first unmanned vessel 60A, the external monitoring performance of the sensor of the second unmanned vessel 60B will affect the effective external monitoring performance of the first unmanned vessel 60A. This step also includes the process of identifying the unmanned vessel with the lowest external monitoring performance as the reference vessel. If the transmission format of the sensor data used for complementation has been changed, the effective external monitoring performance is calculated using the external monitoring performance corresponding to the changed transmission format.

[0062] In step S204, the control device 90 or the ship speed control unit 30 determines whether the effective external monitoring performance of each unmanned vessel 60 calculated in step S203 is above a predetermined threshold. If the effective external monitoring performance of all unmanned vessels 60 is above the predetermined threshold (Yes in step S204), the process proceeds to step S205. If the effective external monitoring performance of at least one unmanned vessel 60 falls below the predetermined threshold (No in step S204), the process proceeds to step S206.

[0063] In step S205, the control device 90 or the speed control unit 30 maintains the current speed limit for each unmanned vessel 60. The process then proceeds to step S209.

[0064] In step S206, the control device 90 or the ship speed control unit 30 lowers the speed limit of the relevant unmanned vessel 60 or the entire group depending on the degree and extent of the deterioration in external monitoring performance. Specifically, the speed limit for the entire group may be set based on the unmanned vessel with the lowest external monitoring performance, or only the speed limit of the unmanned vessels that rely on monitoring supplementation may be lowered. If necessary, a command to increase the distance between multiple unmanned vessels 60 may also be issued.

[0065] In step S207, each unmanned vessel 60 controls its propulsion system 80 based on the new speed limit set in step S206, and controls its cruising speed to be below the speed limit. If a command to increase the formation distance is also issued, each unmanned vessel 60 also increases the formation distance.

[0066] If external monitoring performance is restored (Yes in step S208), proceed to step S209. If external monitoring performance is not restored (No in step S208), proceed to step S210.

[0067] In step S209, the control device 90 or the ship speed control unit 30 gradually increases the speed limit based on the recovered external monitoring performance. It is preferable that the speed limit is increased after sufficient monitoring performance recovery has been confirmed for a predetermined duration. To avoid a sudden increase in speed, the speed limit is increased gradually at a predetermined rate. By synchronously increasing the speed limit for the entire group, the speed difference between each unmanned vessel in the formation is suppressed. The process then proceeds to step S210.

[0068] In step S210, the control device 90 or the ship speed control unit 30 determines whether or not it is necessary to continue sailing. If sailing is to be continued (Yes in step S210), the process returns to step S201; if sailing is to be terminated (No in step S210), the process in this flowchart is terminated.

[0069] The status acquisition unit 20, ship speed control unit 30, and sensor control unit 40 described above may be implemented by the processor 27 executing a program stored in the memory unit 26, or some or all of each function may be implemented by dedicated hardware circuits. The program may be provided on a computer-readable non-temporary recording medium, or it may be provided by download via a communication network. Similarly, the control device 90 is implemented by a computer equipped with a processor, memory, and communication unit 91. The control device 90 may be installed in a land-based control station, mounted on a mother ship, or built on a cloud server.

[0070] In each of the embodiments described above, the external monitoring performance is represented by at least one of the detection distance, identifiable distance, field of view, update cycle, and resolution of the target by the sensor 50 (corresponding to claim 2). The communication state includes at least one of the available bandwidth via the communication unit 25, communication delay, processing delay, and packet loss (corresponding to claim 3). In the second embodiment, the sensor control unit 40 changes the operating mode of the sensor 50 according to the energy state or communication state, and the ship speed control unit 30 sets a speed limit based on the external monitoring performance corresponding to the changed operating mode (corresponding to claim 4). The change in the operating mode includes changing at least one of the resolution, frame rate, sampling cycle, field of view, amount of transmitted data, and transmission method (corresponding to claim 5).

[0071] The ship speed control unit 30 gradually lowers the speed limit in accordance with the amount of decrease in external monitoring performance (corresponding to claim 6). The ship speed control unit 30 sets the speed limit based on the detection distance based on external monitoring performance and the stopping distance or distance required for avoidance of the unmanned vessel (corresponding to claim 7). When the energy state or communication state deteriorates, the ship speed control unit 30 leaves sensors with high operational priority as targets for operation and sets the speed limit based on the external monitoring performance of the remaining sensors (corresponding to claim 8).

[0072] In the third embodiment, when at least a portion of the surrounding monitoring of the first unmanned vessel 60A depends on the sensors of the second unmanned vessel 60B, the speed limit of the first unmanned vessel 60A is set based on the external monitoring performance of the second unmanned vessel 60B (corresponding to claim 10). The speed limit of at least some of the unmanned vessels is set based on the unmanned vessel with the lowest external monitoring performance among the multiple unmanned vessels (corresponding to claim 11). When the overall external monitoring performance of the multiple unmanned vessels deteriorates due to deterioration of the energy state or communication state of at least one unmanned vessel, the speed limit of each unmanned vessel is set to increase the distance between the multiple unmanned vessels (corresponding to claim 12).

[0073] When sailing in a convoy, the speed limit is set considering the monitoring range of sensors of the preceding or adjacent unmanned vessel (corresponding to claim 13). When sensor data acquired by at least one of multiple unmanned vessels is used to supplement the surrounding monitoring of other unmanned vessels, the speed limit of the other unmanned vessels is set based on the external monitoring performance of the sensors used for such supplementation (corresponding to claim 14). When the energy state or communication state of multiple unmanned vessels improves and the overall external monitoring performance recovers, the speed limit is increased based on the recovered external monitoring performance (corresponding to claim 15). When the transmission mode is changed in response to a deterioration in the communication state, the speed limit is set based on the external monitoring performance corresponding to the changed transmission mode (corresponding to claim 16).

[0074] The navigation control processing in the first and second embodiments described above (see Figures 5 and 7) corresponds to an embodiment of the navigation control method for a single unmanned vessel (corresponding to claim 17). Specifically, it includes a step of acquiring the energy state or communication state of one or more sensors provided by the unmanned vessel (step S1 or step S101), a step of setting a speed limit based on the external monitoring performance corresponding to the energy state or communication state (steps S2 and S5 or steps S103 and S106), and a step of lowering the speed limit when the external monitoring performance deteriorates (steps S5 and S6 or steps S106 and S107).

[0075] The navigation control process in the third embodiment described above (see Figure 10) corresponds to an embodiment of the navigation control method for a navigation system including a plurality of unmanned vessels (corresponding to claim 18). Specifically, it includes the steps of acquiring the energy state or communication state of sensors provided by each of the plurality of unmanned vessels (step S201), setting a speed limit based on the external monitoring performance of at least one unmanned vessel (steps S202 to S206), and lowering the speed limit when the external monitoring performance deteriorates (steps S206 and S207).

[0076] The functions of the state acquisition unit 20, the ship speed control unit 30, and the sensor control unit 40 in each of the embodiments described above can be realized by having a computer execute a predetermined program. Specifically, a program (corresponding to claim 19) is provided to cause the computer to execute a process for acquiring the energy state or communication state of one or more sensors, a process for setting a speed limit based on the external monitoring performance corresponding to the energy state or communication state, and a process for lowering the speed limit when the external monitoring performance deteriorates. Similarly, a program (corresponding to claim 20) corresponding to multiple unmanned vessels is also provided. These programs may be stored on a computer-readable non-temporary recording medium or distributed via a communication network.

[0077] (modified version) The present invention is not limited to the embodiments described above. For example, the speed limit may be set by considering both the energy state and the communication state simultaneously, or by considering only one of them. Furthermore, the configurations of the first and second embodiments relating to a single unmanned vessel can be appropriately applied to a third embodiment relating to multiple unmanned vessels. For example, each unmanned vessel 60 in the third embodiment may be equipped with the sensor control unit 40 of the second embodiment.

[0078] Furthermore, the functions of the control device 90 in the third embodiment can also be realized in a distributed manner by each unmanned vessel 60. For example, each unmanned vessel 60 may communicate with each other via the communication unit 25 to grasp the energy status and communication status of other unmanned vessels, and the speed control unit 30 of each unmanned vessel 60 may autonomously set a speed limit. Alternatively, without using the control device 90, a specific unmanned vessel 60 may act as a leader vessel, aggregating information from other unmanned vessels and transmitting commands regarding speed limits to the other unmanned vessels.

[0079] Furthermore, hysteresis may be provided when the speed limit is lowered or raised. That is, by lowering the speed limit when the external monitoring performance falls below a predetermined threshold, and raising the speed limit when it exceeds a recovery threshold which is the threshold plus a predetermined margin, frequent fluctuations in the speed limit near the threshold can be suppressed.

[0080] Furthermore, the unmanned vessel 60 in each of the embodiments described above is not limited to autonomous vessels but may also be remotely operated vessels. In the case of remotely operated vessels, a land-based operator remotely controls the vessel, but even if the quality of video transmission to the operator deteriorates due to a decrease in the communication status via the communication unit 25, the speed limit control of the present invention can be applied. That is, a decrease in the communication status in a remotely operated vessel corresponds to a decrease in the external monitoring performance available to the operator, so the ship speed control unit 30 can lower the speed limit in accordance with this decrease.

[0081] Furthermore, although the embodiments described above mainly describe unmanned vessels navigating the sea, the present invention can also be applied to unmanned vessels navigating rivers, lakes, or harbors. Moreover, the use of the unmanned vessel is not limited and can be applied to unmanned vessels for various purposes such as transportation, surveying, monitoring, and research. In addition, the "speed limit" in the present invention is not limited to water speed, but may be ground speed.Therefore, the present invention can be implemented with various modifications without departing from the gist of the invention as described in the claims. [Explanation of symbols]

[0082] 10 Navigation control system 20 State acquisition unit 25 Communications Department 26 Memory section 27 processors 30 Ship speed control unit 40 Sensor Control Unit 50 sensors 50a Front Camera 50b Forward radar 50c Rear Camera 50d Side auxiliary sensor 60 Unmanned boat 60A First unmanned boat 60B Second unmanned vessel 70 Navigation Systems 80 Propulsion device 90 Control equipment 91 Communication Department (Control Device)

Claims

1. A navigation control system installed on a single unmanned vessel that is an autonomous vessel or a remotely operated vessel, A state acquisition unit that acquires a state quantity indicating the energy state or a state quantity indicating the communication state related to one or more sensors equipped on the aforementioned unmanned vessel, The vessel includes a speed control unit that sets an upper limit on the speed of the unmanned vessel based on the external monitoring performance of one or more sensors that vary according to a state quantity indicating the energy state or a state quantity indicating the communication state, The aforementioned external monitoring performance includes at least the detection distance of the target by the one or more sensors, The ship speed control unit sets the speed limit based on the detection distance and the stopping distance of the unmanned vessel, and lowers the speed limit when the external monitoring performance deteriorates. Navigation control system.

2. In the navigation control system according to claim 1, The state quantity indicating the communication state includes at least one of the available bandwidth value, communication delay time, processing delay time, and packet loss rate. Navigation control system.

3. In the navigation control system according to claim 1, The sensor control unit further comprises a sensor control unit that changes the operating mode of one or more sensors according to a state quantity indicating the energy state or a state quantity indicating the communication state, The ship speed control unit sets the speed limit based on the external monitoring performance corresponding to the changed operating mode. Navigation control system.

4. In the navigation control system according to claim 3, The change in the operating mode includes changing at least one of the following: resolution, frame rate, sampling period, field of view, amount of transmitted data, and transmission method. Navigation control system.

5. In the navigation control system according to claim 1, The ship speed control unit sets the speed limit to a first speed limit when the index value of the external monitoring performance falls below a first threshold, and sets the speed limit to a second speed limit lower than the first speed limit when the index value falls below a second threshold lower than the first threshold. Navigation control system.

6. In the navigation control system according to claim 1, The ship speed control unit changes or stops the operating mode of one or more sensors that have a relatively lower operational priority based on the state quantity indicating the energy state or the state quantity indicating the communication state, maintains the operation of sensors that have a relatively higher operational priority, and sets the speed limit based on the external monitoring performance of the sensors whose operation is maintained. Navigation control system.

7. A navigation system including multiple autonomous or remotely operated unmanned vessels, A state acquisition unit that acquires a state quantity indicating the energy state or a state quantity indicating the communication state related to one or more sensors each of the aforementioned multiple unmanned vessels, When monitoring the blind spots of the first unmanned vessel among the plurality of unmanned vessels in the lateral or forward diagonal direction is supplemented by sensor data acquired by the second unmanned vessel among the plurality of unmanned vessels, a speed control unit sets the upper speed limit of the first unmanned vessel based on the external monitoring performance, which is represented by at least one of the target detection distance, identifiable distance, field of view, update cycle, and resolution of the sensor of the second unmanned vessel used for the supplementation, Equipped with, The ship speed control unit reduces the speed limit of the first unmanned vessel when the external monitoring performance of the sensor of the second unmanned vessel used for complementation decreases due to a change in the state quantity indicating the energy state or the state quantity indicating the communication state of the second unmanned vessel. Navigation system.

8. In the navigation system according to claim 7, The ship speed control unit sets a speed limit for at least some of the unmanned vessels among the plurality of unmanned vessels based on the unmanned vessel with the lowest external monitoring performance among the plurality of unmanned vessels. Navigation system.

9. In the navigation system according to claim 7, The ship speed control unit, when the overall external monitoring performance of the multiple unmanned vessels deteriorates due to a change in a state quantity indicating the energy state or communication state of at least one of the multiple unmanned vessels, lowers the speed limit of at least some of the multiple unmanned vessels and issues a command to widen the formation distance to the multiple unmanned vessels. Navigation system.

10. In the navigation system according to claim 7, The aforementioned speed control unit sets the speed limit when the multiple unmanned vessels are sailing in formation, taking into consideration the monitoring range of the sensors of the preceding unmanned vessel or the unmanned vessel sailing to the side. Navigation system.

11. In the navigation system according to claim 7, The speed control unit, based on a state quantity indicating the energy state or communication state of the plurality of unmanned vessels, determines that the overall external monitoring performance of the plurality of unmanned vessels has recovered, and increases the speed limit based on the recovered external monitoring performance. Navigation system.

12. In the navigation system according to claim 7, In response to a change in the state quantity indicating the communication status of the second unmanned vessel, the transmission format of the sensor data transmitted from the second unmanned vessel to the first unmanned vessel or control device is changed to either image data, region extraction data, feature data, or metadata. The ship speed control unit sets the speed limit of the first unmanned vessel based on the external monitoring performance of the second unmanned vessel's sensor corresponding to the modified transmission mode. Navigation system.

13. A method for controlling the navigation of a single unmanned vessel, A step of acquiring a state quantity indicating the energy state or communication state of one or more sensors provided by the unmanned vessel, A step of setting an upper speed limit for the unmanned vessel based on the detection distance of the target by one or more sensors and the stopping distance of the unmanned vessel, which are included in the external monitoring performance that varies according to the state quantity indicating the energy state or the state quantity indicating the communication state, A step of reducing the speed limit when the external monitoring performance deteriorates, A navigation control method including a method.

14. A method for controlling the navigation of a navigation system including multiple unmanned vessels, A step of acquiring a state quantity indicating the energy state or communication state related to one or more sensors each of the aforementioned multiple unmanned vessels, When monitoring the blind spots of the first unmanned vessel among the plurality of unmanned vessels in the lateral or forward diagonal direction is supplemented by sensor data acquired by the second unmanned vessel among the plurality of unmanned vessels, the process of setting an upper speed limit for the first unmanned vessel based on the external monitoring performance, which is represented by at least one of the target detection distance, identifiable distance, field of view, update cycle, and resolution of the sensor of the second unmanned vessel used for the supplementation, A step of reducing the speed limit of the first unmanned vessel when the external monitoring performance of the sensor of the second unmanned vessel used for complementation decreases due to a change in the state quantity indicating the energy state or the state quantity indicating the communication state of the second unmanned vessel, A navigation control method including a method.

15. On the computer, A process for acquiring a state quantity indicating the energy state or communication state of one or more sensors equipped on a single unmanned vessel, A process for setting an upper speed limit for the unmanned vessel based on the detection distance of the target by one or more sensors and the stopping distance of the unmanned vessel, which is included in the external monitoring performance that varies according to the state quantity indicating the energy state or the state quantity indicating the communication state, A process to reduce the speed limit when the external monitoring performance deteriorates, A program to execute.

16. On the computer, A process for acquiring a state quantity indicating the energy state or communication state related to one or more sensors equipped on each of multiple unmanned vessels, When monitoring the blind spots of the first unmanned vessel among the plurality of unmanned vessels in the lateral or forward diagonal direction is supplemented by sensor data acquired by the second unmanned vessel among the plurality of unmanned vessels, the process of setting the speed limit of the first unmanned vessel based on the external monitoring performance, which is represented by at least one of the target detection distance, identifiable distance, field of view, update cycle, and resolution of the sensor of the second unmanned vessel used for the supplementation, When the external monitoring performance of the sensor of the second unmanned vessel used for the complementation decreases due to a change in the state quantity indicating the energy state or the state quantity indicating the communication state of the second unmanned vessel, the process of reducing the speed limit of the first unmanned vessel is performed. A program to execute.

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