Ship control device, ship, ship control method, and program

Abstract

A ship control device according to the present invention comprises an area information acquisition unit that acquires area information that specifies a first area that is near a target location and a second area that is farther from the target location than the first area but is near the first area, a self location information acquisition unit that acquires location information for a self ship, a direction control unit that, when the location of the self ship as acquired by the self location information acquisition unit is in the second area, controls the direction in which the bow is pointed to be toward the target location, and an output control unit that, when the location of the self ship as acquired by the self location information acquisition unit is in a third area that is farther from the target location than the first area and the second area but is near the second area, controls thrust such that the self ship moves toward the target location.

Description

Ship control device, ship, ship control method and program

[0001] This application claims priority to Japanese Patent Application No. 2023-185239, filed on October 30, 2023, the contents of which are incorporated herein by reference.

[0002] Conventionally, there are known techniques for steadily keeping a ship in the same position on the sea where there are external disturbances such as wind, currents, etc. For example, there is known a technique for keeping a ship in the same position by controlling the movement of the ship so that the bow points toward a predetermined target point and the ship moves forward and backward when the ship drifts a predetermined distance or for a predetermined time (see, for example, Patent Document 1).

[0003] JP 2014-24421 A

[0004] However, depending on the shape of the vessel, it is difficult to move in a straight line when reversing, and some vessels have shapes that cause the vessel to wobble when reversing. In the case of such vessels, if a technique for maintaining the vessel in the same position by moving forward and backward, as in the conventional technique, is used, the vessel cannot move stably when reversing, which causes anxiety for those on board. Therefore, there is a need for a method for maintaining a fixed position in an appropriate manner.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a ship control device, a ship, a ship control method, and a program that are capable of preferably maintaining a fixed position.

[0006] One aspect of the present invention is a ship control device that includes: an area information acquisition unit that acquires area information identifying a first range that is close to a target position and a second range that is farther from the target position than the first range and is close to the first range; a host position information acquisition unit that acquires position information of the ship; a direction control unit that controls the direction in which the bow faces to face the target position when the position of the ship acquired by the host position information acquisition unit is within the second range; and an output control unit that controls thrust to move the ship toward the target position when the position of the ship acquired by the host position information acquisition unit is within a third range that is farther from the target position than the first range and the second range and is close to the second range.

[0007] One aspect of the present invention is a ship control device that includes a position information acquisition unit that acquires position information of the ship itself, a direction control unit that controls the direction in which the bow faces to face the target position when the distance from the target position of the ship acquired by the position information acquisition unit is less than a threshold value, and an output control unit that controls thrust to move the ship toward the target position when the distance from the target position of the ship acquired by the position information acquisition unit is farther than the threshold value.

[0008] One aspect of the present invention is a ship control method comprising: an area information acquisition process for acquiring area information that identifies a first range that is close to a target position and a second range that is farther from the target position than the first range and is close to the first range; a ship's own position information acquisition process for acquiring ship's own position information; a heading control process for controlling the heading of the ship's bow so that it faces the target position when the ship's own position acquired by the ship's own position information acquisition process is within the second range; and an output control process for controlling thrust so that the ship moves toward the target position when the ship's own position acquired by the ship's own position information acquisition process is within a third range that is farther from the target position than the first range and the second range and is close to the second range.

[0009] One aspect of the present invention is a program that causes a computer to execute the following steps: an area information acquisition step that acquires area information that identifies a first range that is close to a target position and a second range that is farther from the target position than the first range and is close to the first range; a position information acquisition step that acquires position information of the ship; a heading control step that controls the heading of the bow so that the ship faces the target position if the position of the ship acquired by the position information acquisition step is within the second range; and an output control step that controls thrust so that the ship moves toward the target position if the position of the ship acquired by the position information acquisition step is within a third range that is farther from the target position than the first range and the second range and is close to the second range.

[0010] According to the present invention, it is possible to provide a ship control device, a ship, a ship control method, and a program that are capable of preferably maintaining a fixed position.

[0011] FIG. 1 is a diagram for explaining area information according to one embodiment. FIG. 1 is a diagram for explaining an example of processing when a vessel according to one embodiment is located in a hold OK area. FIG. 2 is a diagram for explaining an example of processing when a vessel according to one embodiment is located in a heading control area. FIG. 2 is a diagram for explaining an example of processing when a vessel according to one embodiment is located in a regression control area. A functional configuration diagram showing an example of the functional configuration of a vessel according to one embodiment. A functional configuration diagram showing an example of the functional configuration of a vessel control device according to one embodiment. A flowchart showing a series of steps of a vessel control method according to one embodiment. A first diagram for explaining conditions under which heading control is performed in the vessel control method according to one embodiment. A second diagram for explaining conditions under which heading control is performed in the vessel control method according to one embodiment. A functional configuration diagram showing an example of an internal block diagram of a vessel control device according to one embodiment.

[0012] [Embodiments] Preferred embodiments of a ship control device, a ship, a ship control method, and a program according to aspects of the present invention will be described in detail below with reference to the accompanying drawings. Note that aspects of the present invention are not limited to these embodiments and include various modifications or improvements. In other words, the components described below include those that a person skilled in the art would easily imagine or that are substantially identical, and the components described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the present invention. In addition, in the drawings below, the scale and number of components may differ from the scale and number of the actual structures to make each configuration easier to understand.

[0013] FIG. 1 is a diagram for explaining area information according to one embodiment. First, with reference to the figure, the area information used for controlling the vessel 1 according to this embodiment will be explained. The figure shows a plan view of the sea as seen from directly above. The vessel control device, vessel, vessel control method, and program according to this embodiment control the vessel 1 to steadily stay at the target position shown in the figure. In the following description, control to steadily keep the vessel 1 at a predetermined position may be referred to as fixed point maintenance control. Fixed point maintenance control is control that is performed, for example, when the vessel 1 is in fixed point maintenance mode.

[0014] For example, the vessel 1 transitions to fixed-point holding mode, with its current position set as the target position. In this case, the vessel 1 acquires position information at the time of transition to fixed-point holding mode from a GPS (Global Positioning System) device (not shown). The position information may be represented by, for example, two-dimensional coordinates. An example of two-dimensional coordinates may be GPS coordinate information including latitude and longitude. The vessel 1 may transition to fixed-point holding mode, with a point far away from its current vessel set as the target position. The target position is preferably a point, but may also be a circle having a predetermined area. Next, the vessel 1 defines a hold-OK area, a heading control area, and a return control area using the position information as the target position. An example of each area will be described below.

[0015] The hold-OK area is a range close to the target position. The hold-OK area may be a range that includes the target position. The hold-OK area may be, for example, a circle centered on the target position and having a radius R1. In the following description, the hold-OK area may be referred to as a first range.

[0016] The azimuth control area is a range farther from the target position than the hold-OK area and closer to the hold-OK area. More specifically, the azimuth control area may be a ring having an inner circle adjacent to the outer periphery of the hold-OK area (i.e., a circle centered at the target position and having a radius R1) and an outer circle of a radius R2. The ring is defined on a two-dimensional plane. In other words, the ring has a donut shape formed by concentric circles with radii R1 and R2. Here, the radii R1 and R2 have different lengths. Furthermore, the inner and outer circles of the ring that is the azimuth control area are circles centered at the same point (the target position). In the following description, the azimuth control area may be referred to as a second range.

[0017] In the illustrated example, the hold-OK area and the orientation control area are depicted as circles, but this embodiment is not limited to this example and may be shaped other than circles. The shapes of the hold-OK area and the orientation control area may be, for example, an ellipse or other shape modified depending on the direction and magnitude of the disturbance vector. Furthermore, if an immovable object such as a levee exists within the range of the hold-OK area and the orientation control area, the object may be designated as outside the range. Furthermore, if an immovable object such as a levee exists, the shapes of the hold-OK area and the orientation control area may be set to exclude the object (or to exclude a range including a predetermined margin from the object). Furthermore, in the following description, the hold-OK area and the orientation control area are depicted as concentric circles with different radii, but this embodiment is not limited to this example. For example, the hold-OK area and the orientation control area may be the same area.

[0018] The regression control area is a range that exists outside the outer circle of the heading control area. In other words, the regression control area is a range that is farther from the target position than the hold OK area and the heading control area. The regression control area is also a range that is close to the heading control area. In the example shown, the regression control area has a shape without an outer edge, but it may be configured to have an outer edge. The boundary between the regression control area and the heading control area may be a circle with a radius R2 centered on the target position. In the following description, the regression control area may be referred to as the third range.

[0019] The vessel 1 maintains a fixed position by performing different control depending on which of the three areas the vessel is located in. Next, with reference to Figures 2 to 4, an example of control when the vessel 1 is located in each area will be described.

[0020] 2 is a diagram for explaining an example of processing when the ship according to this embodiment is located in a holding-OK area. First, an example of processing when the ship 1 is located in the holding-OK area will be explained. When the ship 1 is located within the holding-OK area, the ship 1 is controlled to maintain the heading of the hull.

[0021] When the vessel 1 enters the fixed position holding mode while the vessel is at the target position, the vessel 1 is controlled to maintain the vessel's heading at the time of entering the fixed position holding mode. Note that the heading maintained by the vessel 1 in the holding OK area may be another heading. For example, if the vessel 1 leaves the holding OK area once and then re-enters the holding OK area, the vessel 1 may maintain the heading at the time of returning to the holding OK area.

[0022] (1) in the figure shows the position and heading of the vessel 1 at the time when the fixed position holding mode is entered. At this time, the vessel 1 can be said to be directly above the target position. Also, at this time, the vessel 1 is in an idle state. (2) in the figure shows the position and heading of the vessel 1 when the heading is tilted due to external disturbances such as wind or current. The vessel 1 automatically steers in the opposite direction to the heading tilted in the idle state. (3) in the figure shows that the vessel 1 has returned to the heading shown in (1) by turning the rudder in the opposite direction. Within the holding OK area, the vessel 1 is controlled to maintain its heading by repeating the operations (1) to (3) shown in the figure.

[0023] 3 is a diagram for explaining an example of processing when the ship according to this embodiment is located in a heading control area. Next, an example of processing when the ship 1 is located in the heading control area will be explained. The heading control area is a preparation area for returning the ship 1 that has moved out of the range of the holding OK area to the holding OK area. When the ship 1 is located within the range of the heading control area, the ship 1 is controlled to turn so that the heading of the hull is facing the target position and to maintain that heading.

[0024] (1) in the figure shows the position and heading of the vessel 1 when the vessel 1 leaves the range of the OK-to-hold area and enters the range of the heading control area. As shown in the figure, the position and heading of the vessel 1 are directed to the heading of the vessel 1 at the time of entering the fixed-point holding mode as a result of the control described with reference to Figure 2. In the heading control area, the vessel maintains an idle state and automatically steers the vessel so that its heading points toward the target position. (2) in the figure shows that the vessel has returned to a heading pointing toward the target position by steering the vessel so that its heading points toward the target position. (3) in the figure shows a state in which the vessel 1 drifts due to external disturbances such as wind or currents, causing the vessel's heading to tilt, and the vessel is automatically steered to point toward the target position. Within the heading control area, the vessel 1 is controlled to maintain a heading pointing toward the target position by repeating the operations (1) to (3) shown in the figure.

[0025] Figure 4 is a diagram for explaining an example of processing when the vessel according to this embodiment is located in a regression control area. Next, an example of processing when the vessel 1 is located in the regression control area will be described. When the position of the vessel 1 moves from within the range of the heading control area to within the range of the regression control area, the vessel 1 is controlled to return the hull to the target position. Once the vessel 1 has entered the range of the regression control area, the bow is oriented toward the target position through the control described with reference to Figure 3, so that by outputting forward thrust as is, the vessel 1 can move forward to the target position, and the position of the vessel 1 can be moved to the target position.

[0026] The (1) in the figure indicates the position and heading of the vessel 1 when the vessel 1 leaves the heading control area and enters the return control area. As shown in the figure, the bow of the vessel 1 is pointing toward the target position, so it is possible to return to the target position by proceeding in the direction indicated by the arrow in the figure. When the vessel 1 detects that its own position has reached the target position, it returns to the idle state and performs control within the holding OK area described with reference to Figure 2.

[0027] The vessel 1 may return to an idle state at a position where it is in balance with the disturbance before its own position reaches the target position. That is, the vessel 1 may be in a state where it remains in deviation from the target position without returning to the holding OK area. By performing such control, the vessel 1 is in a state where it is in balance with the disturbance, and from that point on, it will no longer move forward or backward.

[0028] FIG. 5 is a diagram illustrating an example of the functional configuration of the boat 1 according to the first embodiment. An example of the functional configuration of the boat 1 will be described with reference to the diagram. The boat 1 includes at least an actuator 11, an operation unit 12, a boat control device 13, a time measurement unit 14, a boat position detection unit 15, a bow direction detection unit 16, and a notification unit 17 as functional components. The boat 1 may be a personal watercraft (PWC) having basic functions similar to those of a PWC (personal watercraft) described in, for example, FIG. 1 of Japanese Patent Application Laid-Open No. 2003-237693 and Japanese Patent Application Laid-Open No. 2014-073790.

[0029] The actuator 11 has a function of generating thrust for the vessel 1 and a function of generating a moment for the vessel 1. Specifically, the actuator 11 includes an engine 111 and a jet propulsion device 112. The engine 111 outputs driving force. The engine 111 is configured similarly to the engine shown in, for example, FIG. 1 of Japanese Patent Application Laid-Open No. 2014-073790. The jet propulsion device 112 generates thrust for the vessel 1 by the driving force output from the engine 111. The jet propulsion device 112 is configured similarly to the jet propulsion device shown in, for example, FIG. 1 of Japanese Patent Application Laid-Open No. 2003-237693. The jet propulsion device 112 includes a nozzle 112A and a bucket 112B. The nozzle 112A ejects a jet flow generated by the driving force output from the engine 111. The nozzle 112A is configured similarly to the nozzle shown in, for example, FIG. 1 of Japanese Patent Application Laid-Open No. 2003-237693. The bucket 112B changes the direction of the jet flow ejected from the nozzle 112A. The bucket 112B has the same configuration as the bucket shown in, for example, FIG. 1 of Japanese Patent Application Laid-Open No. 2003-237693.

[0030] The operation unit 12 accepts input operations from the vessel operator (user) to operate the actuator 11. The operation unit 12 includes a throttle operation unit 121, a shift operation unit 122, a steering unit 123, and a fixed position holding mode setting unit 124. The throttle operation unit 121 is configured similarly to the throttle operation unit described in, for example, Japanese Patent Application Laid-Open No. 2014-073790, and accepts input operations from the vessel operator to adjust the rotational speed of the engine 111. The shift operation unit 122 is configured similarly to the shift operation unit described in, for example, Japanese Patent Application Laid-Open No. 2014-073790, and accepts input operations from the vessel operator to switch the position of the bucket 112B between a forward position, a neutral position, and a reverse position. When the steering unit 123 accepts input operations from the vessel operator, the actuator 11 generates a moment on the vessel 1. The steering unit 123 and the throttle operation unit 121 are configured in the same manner as, for example, the steering handle device shown in FIG. 1 of Japanese Patent No. 5196649 and the steering unit shown in FIG. 1 of Japanese Patent Laid-Open No. 2019-171925. The fixed position holding mode setting unit 124 accepts an input operation by the operator to set the vessel control device 13 to a vessel fixed position holding mode, which will be described later.

[0031] The ship control device 13 has a function of controlling the movement of the ship 1 by operating the actuator 11 in response to an input operation from the ship operator received by the operation unit 12. The ship control device 13 also has a normal operation mode in which the actuator 11 is operated in response to an input operation from the ship operator received by the operation unit 12, and a ship fixed position mode in which the operation unit 12 operates the actuator 11 without the need for receiving an input operation from the ship operator after the fixed position mode setting unit 124 receives an input operation from the ship operator to set the ship control device 13 to the ship fixed position mode.

[0032] The time measurement unit 14 measures time.

[0033] The vessel position detection unit 15 detects the actual vessel position, which is the actual position of the vessel 1. The vessel position detection unit 15 includes, for example, a GPS device (not shown). The GPS device calculates the position coordinates of the vessel 1 by receiving signals from multiple GPS satellites.

[0034] The bow direction detection unit 16 detects the bow direction of the ship 1. The bow direction detection unit 16 includes, for example, a direction sensor. The direction sensor calculates the actual bow direction of the ship 1 by using, for example, geomagnetism. In another example, the direction sensor may be a device (gyrocompass) in which a north-pointing device and a vibration-damping device are added to a high-speed rotating gyroscope so that the device always points north. In yet another example, the direction sensor may be a GPS compass that includes multiple GPS antennas and calculates the bow direction from the relative positional relationship of the multiple GPS antennas.

[0035] The notification unit 17 notifies the vessel operator, etc. The notification unit 17 notifies the vessel operator, etc., for example, by outputting a sound. In another example, the notification unit 17 may notify the vessel operator, etc., by displaying a message on a display or vibrating the steering wheel, the vessel operator's seat, etc. The notification unit 17 may notify the vessel operator, etc., for example, that the vessel 1 has entered a fixed point holding mode, or that the vessel operator's position is in a holding OK area, a heading control area, or a return control area.

[0036] FIG. 6 is a functional configuration diagram showing an example of the functional configuration of the ship control device according to this embodiment. An example of the functional configuration of the ship control device 13 will be described with reference to the diagram. The ship control device 13 includes at least a mode detection unit 131, an area information storage unit 132, an area information acquisition unit 133, a position information acquisition unit 134, a movement control unit 135, an output control unit 136, a direction control unit 137, a direction storage unit 138, and a memory control unit 139. Each of these functional units is implemented using, for example, electronic circuits. Each functional unit may also include internal storage means such as a semiconductor memory or a magnetic hard disk drive, as necessary. Each function may also be implemented by a computer having a central processing unit (CPU) and software. Furthermore, all or part of each functional unit may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field-Programmable Gate Array), etc. Furthermore, all or part of each functional unit may be realized by a combination of software and hardware.

[0037] The mode detection unit 131 detects that the fixed point holding mode has been entered. The detection of the entry into the fixed point holding mode is performed, for example, based on an operation by the user. The user may instruct the boat 1 to enter the fixed point holding mode by operating the operation unit 12, or may instruct the boat 1 to enter the fixed point holding mode by operating a terminal device (not shown). The mode detection unit 131 outputs information indicating whether the boat 1 is currently in the fixed point holding mode to the movement control unit 135.

[0038] The area information storage unit 132 acquires area information. The area information includes at least information specifying a hold-OK area and information specifying a direction control area. The information specifying each area may include the position coordinates and radius of a target point. The area information is stored in, for example, the area information acquisition unit 133. The area information acquisition unit 133 may update the area information stored therein based on an operation from the operation unit 12, or may update the area information stored therein based on information acquired from a user via a communication unit (not shown).

[0039] The own position information acquisition unit 134 acquires the own ship's position information from the ship position detection unit 15. The own position information acquisition unit 134 outputs the acquired own ship's position information to the movement control unit 135.

[0040] The movement control unit 135 controls the position and heading of the ship 1 in the fixed point holding mode. Specifically, the movement control unit 135 includes an output control unit 136 and a heading control unit 137, thereby controlling the position and heading of the ship 1.

[0041] When the ship's position acquired by the ship's position information acquisition unit 134 is within the regression control area, the output control unit 136 controls the thrust so that the ship moves toward the target position. Specifically, the output control unit 136 controls the thrust so that the ship moves toward the target position (forward) by outputting forward thrust. When the ship's position passes the target position, the output control unit 136 controls the thrust to neutral. According to this embodiment, azimuth control is performed in the direction from the drifting direction toward the target position. In other words, when heading toward the target position, the traveling direction is opposite to the disturbance, so setting the neutral position causes the ship to move backward. Therefore, according to this embodiment, controlling the thrust to neutral allows the ship to move backward without revving the engine. Note that when the output control unit 136 receives throttle operation from the user, it may end the fixed point holding mode and control the output by prioritizing the throttle operation.

[0042] The heading control unit 137 controls the heading of the bow to maintain its heading when the ship's position acquired by the position information acquisition unit 134 is within the range of the holding OK area. Furthermore, when the ship's position acquired by the position information acquisition unit 134 is within the range of the heading control area, the heading control unit 137 controls the heading of the bow to orient it toward the target position. Note that control when the ship's position is within the holding OK area does not necessarily have to be performed, and this control may be omitted.

[0043] Here, when the ship is located within the range of the hold OK area, the direction in which the bow should point may be stored in the direction memory unit 138. That is, when the ship's position acquired by the ship's position information acquisition unit 134 is located within the range of the hold OK area, the direction control unit 137 controls the direction memory unit 138 to maintain the direction stored in the direction memory unit 138. The direction memory unit 138 stores the direction in which the ship is facing when the fixed point holding mode is entered.

[0044] If the ship 1 leaves the range of the holding-OK area and then re-enters the range of the holding-OK area, the orientation storage unit 138 may update the stored orientation. That is, the orientation storage unit 138 may store the orientation at the time when the ship 1 returns to the target position by the thrust controlled by the output control unit 136. In this case, if the position of the ship acquired by the position information acquisition unit 134 is within the holding-OK area, the orientation control unit 137 stores the position in the orientation storage unit 138 and controls the updated orientation to be maintained.

[0045] The memory control unit 139 acquires area information from the area information memory unit 132 and acquires the position information of the ship from the position information acquisition unit 134. When the ship 1 once leaves the range of the holding OK area and then re-enters the range of the holding OK area, the memory control unit 139 updates the direction stored in the direction memory unit 138.

[0046] FIG. 7 is a flowchart showing a series of steps in the vessel control method according to this embodiment. The series of steps in the vessel control method performed by the vessel control device 13 provided in the vessel 1 will be described with reference to FIG. 7. The processing shown in FIG. 7 can also be said to be processing related to the fixed position holding mode described above. When the fixed position holding mode is entered, the processing shown in FIG. 7 is started, and when an instruction to end the fixed position holding mode is received, the processing shown in FIG. 7 ends. It should be noted that in this embodiment, the vessel 1 acquires its own position information at a predetermined interval. Specifically, the predetermined interval may be 500 ms (milliseconds), for example.

[0047] First, the vessel 1 acquires information about the target position from the user, and acquires area information from the area information storage unit 132 (step S71). Thereafter, the vessel 1 is controlled to maintain the current heading.

[0048] If the predetermined condition is met, the ship 1 proceeds to step S74 and continues the control of step S72 to maintain the current heading until the predetermined condition is met (step S73). The predetermined condition is when the ship's position is outside the first region and the target position is on the bow side. The predetermined condition will be described in detail below with reference to Figures 8 and 9.

[0049] 8 is a first diagram for explaining the conditions for determining whether a vessel is to be subjected to heading control in the vessel control method according to this embodiment. This diagram shows whether a vessel is to be subjected to heading control, based on the target position and the vessel's own position. "Yes" means that the vessel is to be subjected to heading control, and "No" means that the vessel is not to be subjected to heading control.

[0050] Specifically, if the target position is on the bow side and the ship's position is outside the first area, the ship is selected as a target for azimuth control (i.e., Yes). Also, if the target position is on the bow side and the ship's position is within the first area, the ship is not selected as a target for azimuth control (i.e., No). Also, if the target position is on the stern side and the ship's position is outside the first area, the ship is not selected as a target for azimuth control (i.e., No). Also, if the target position is on the stern side and the ship's position is within the first area, the ship is not selected as a target for azimuth control (i.e., No).

[0051] 9 is a second diagram for explaining the conditions under which heading control is performed in the vessel control method according to this embodiment. This diagram explains the conditions under which heading control is performed, using a plan view of the sea as seen from directly above. This diagram illustrates the cases in which the vessel 1 is at positions P1, P2, P3, and P4. In the diagram, the vessel 1 is shown as an isosceles triangle, with the apex indicating the bow and the base indicating the stern.

[0052] First, when the vessel 1 is at position P1, the vessel 1 is located outside the first area and the target position is on the bow side. In this case, it is a target for performing heading control (i.e., Yes). Furthermore, when the vessel 1 is at position P2, the vessel 1 is located within the first area and the target position is on the bow side. In this case, it is not a target for performing heading control (i.e., No). Furthermore, when the vessel 1 is at position P3, the vessel 1 is located outside the first area and the target position is on the stern side. In this case, it is not a target for performing heading control (i.e., No). Furthermore, when the vessel 1 is at position P4, the vessel 1 is located within the first area and the target position is on the stern side. In this case, it is not a target for performing heading control (i.e., No).

[0053] Returning to Fig. 7, the description of the processing related to the fixed position holding mode continues. If it is determined that heading control is to be performed based on the determination criteria described with reference to Figs. 8 and 9, the vessel 1 performs heading control so that the bow points in the direction of the target position (step S74).

[0054] Next, it is determined whether the ship's position is outside the second region (step S75). If the ship's position is not outside the second region, step S74 is repeated, and the ship 1 performs azimuth control so that the bow points in the direction of the target position. If the ship's position is outside the second region, the process proceeds to step S76.

[0055] If the vessel 1 is located outside the second region, the vessel 1 first performs heading control so that the bow points toward the target position. That is, the same control as in step S74 is performed. Furthermore, if the vessel 1 is located outside the second region, the vessel 1 generates thrust to maintain a fixed position (to move) (step S76). It is preferable that the thrust generated by the vessel 1 be a thrust corresponding to the distance between the target position and the vessel 1. Specifically, it is preferable that the thrust be large when the distance between the target position and the vessel 1 is long, and that the thrust be small when the distance between the target position and the vessel 1 is short.

[0056] Second, the vessel 1 generates thrust according to the distance between the target position and the vessel itself, and returns to the target point. If the vessel's position falls within the first region, the vessel 1 stops generating thrust and returns to step S72 (step S77; YES). Furthermore, the vessel 1 generates thrust and attempts to return to the target point until the vessel's position returns to the first region (step S77; NO). In this way, the vessel 1 controls the vessel 1 to enter the first region by generating propulsive force from step S76 to step S77. Even after the vessel 1 controls the thrust to move toward the target position by outputting forward thrust, the vessel 1 may not reach the first range and may end up in the second range, for example, if external disturbances increase compared to the time of calculation. Even in such a case, the vessel 1 does not generate any further thrust and controls the heading of the bow to face the target position.

[0057] When the vessel 1 passes through the first region, it reaches the second region and enters the state shown as position P3. In this case, the vessel 1 is controlled to maintain its current heading based on the determination in step S73 (i.e., step S73; NO). In this case, the vessel 1 does not need to generate astern propulsion even when it passes through the first region.

[0058] FIG. 10 is a block diagram showing an example of the internal configuration of the vessel control device 13 of this embodiment. At least some of the functions of the vessel control device 13 can be implemented using a computer. As shown in the figure, the computer includes a central processing unit 901, a RAM 902, an input / output port 903, input / output devices 904 and 905, and a bus 906. The computer itself can be implemented using existing technology. The central processing unit 901 executes instructions contained in a program read from the RAM 902 or the like. In accordance with each instruction, the central processing unit 901 writes data to the RAM 902, reads data from the RAM 902, and performs arithmetic and logical operations. The RAM 902 stores data and programs. Each element included in the RAM 902 has an address and can be accessed using the address. RAM is an abbreviation for "random access memory." The input / output port 903 is a port through which the central processing unit 901 exchanges data with external input / output devices. The input / output devices 904 and 905 are input / output devices. The input / output devices 904 and 905 exchange data with the central processing unit 901 via the input / output port 903. The bus 906 is a common communication path used within the computer. For example, the central processing unit 901 reads and writes data from and to the RAM 902 via the bus 906. For example, the central processing unit 901 accesses the input / output port via the bus 906. In addition, all or part of the functional units of the vessel control device 13 may be implemented using hardware such as an ASIC, a PLD, or an FPGA. In addition, all or part of the functional units may be implemented using a combination of software and hardware.

[0059] Summary of this embodiment According to the embodiment described above, the ship control device 13 is equipped with an area information acquisition unit 133, which acquires area information identifying a first range (i.e., a hold-OK area) that is close to the target position and a second range (i.e., a heading control area) that is a range that is farther from the target position than the first range and close to the first range, and is equipped with a host position information acquisition unit 134, which acquires the position information of the ship itself. Furthermore, the ship control device 13 is equipped with a heading control unit 137, which controls the heading of the bow to be maintained when the position of the ship acquired by the host position information acquisition unit 134 is within the first range, and controls the heading of the bow to be oriented toward the target position when the position of the ship acquired by the host position information acquisition unit 134 is within the second range. Furthermore, the vessel control device 13 includes an output control unit 136, and when the vessel's position acquired by the vessel position information acquisition unit 134 is within a third range, which is farther from the target position than the first and second ranges and closer to the second range, the vessel control device 13 controls the thrust to move the vessel toward the target position. That is, according to this embodiment, the area in which the vessel changes direction and the area in which the vessel moves forward are separated. Near the target position, the vessel changes only the direction of the bow in an idle state, and when the vessel moves away from the target position, the engine is revved up to return to the target position. That is, according to this embodiment, a fixed position can be maintained by moving forward without moving astern. Therefore, this embodiment solves the problem associated with the prior art, which is that the technique of maintaining the vessel in the same position by moving forward and backward is unstable. Therefore, this embodiment achieves the effect of being able to maintain a fixed position in an optimal manner.

[0060] Furthermore, according to the embodiment described above, when maintaining a fixed position, the ship's position is determined and appropriately controlled using the range acquired by the area information acquisition unit 133. However, this embodiment is not limited to this example, and the ship's position may be determined and controlled using a threshold value. That is, the ship control device 13 may include the ship's position information acquisition unit 134 to acquire the ship's position information, the heading control unit 137 to control the heading of the bow to face the target position when the distance from the target position to the ship's position acquired by the ship's position information acquisition unit 134 is equal to or less than a threshold value, and the output control unit 136 to control the thrust to move the ship toward the target position when the distance from the ship's position acquired by the ship's position information acquisition unit 134 to the target position is greater than the threshold value. According to this embodiment, maintaining a fixed position can be achieved by moving forward without reversing. Therefore, this embodiment can solve the problem associated with the prior art, which is that the technique of maintaining a ship in the same position by moving forward and backward can be unstable. Therefore, this embodiment can achieve the effect of maintaining a fixed position in an optimal manner.

[0061] Furthermore, according to the embodiment described above, the vessel control device 13 described above has a variable threshold for determining whether to control the thrust to move the vessel toward the target position. The threshold may be based on position information of the vessel relative to the target position or an external factor. By adopting such a configuration, it is possible to control the vessel so that it begins to move toward the target position at an appropriate position.

[0062] The functions of the components of the vessel control device, vessel, vessel hull control method, and program according to the above-described embodiments may be realized in whole or in part by recording a program for realizing these functions on a computer-readable recording medium, and then loading and executing the program recorded on the recording medium into a computer system. Note that the term "computer system" here includes hardware such as an OS and peripheral devices.

[0063] Furthermore, "computer-readable recording media" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage units such as hard disks built into computer systems. Furthermore, "computer-readable recording media" may also include devices that dynamically store programs for a short period of time, such as communication lines used when transmitting programs over networks like the Internet or communication lines like telephone lines, or devices that store programs for a fixed period of time, such as volatile memory within computer systems that serve as servers or clients in such cases. Furthermore, the above-mentioned programs may be programs that realize some of the aforementioned functions, or may be programs that can realize the aforementioned functions in combination with programs already stored in the computer system.

[0064] The above describes the form for carrying out the present invention using an embodiment, but the present invention is not limited to such an embodiment, and various modifications and substitutions can be made within the scope that does not deviate from the spirit of the present invention.

[0065] According to the present invention, a fixed point can be maintained in an appropriate manner.

[0066] 1...ship, 11...actuator, 12...operation unit, 13...ship control device, 14...time measurement unit, 15...ship position detection unit, 16...bow direction detection unit, 17...notification unit, 111...engine, 112...jet propulsion device, 112A...nozzle, 112B...bucket, 121...throttle operation unit, 122...shift operation unit, 123...steering unit, 124...fixed point holding mode setting unit, 131...mode detection unit, 132...area information storage unit, 133...area information acquisition unit, 134...self-position information acquisition unit, 135...movement control unit, 136...output control unit, 137...direction control unit, 138...direction storage unit, 139...storage control unit

Claims

1. A ship control device comprising: an area information acquisition unit that acquires area information identifying a first range close to a target position and a second range that is a range farther from the target position than the first range and close to the first range; a ship's own position information acquisition unit that acquires position information of the ship; a heading control unit that controls the heading of the bow to face the target position when the ship's own position acquired by the ship's own position information acquisition unit is within the second range; and an output control unit that controls thrust to move the ship toward the target position when the ship's own position acquired by the ship's own position information acquisition unit is outside the second range.

2. A ship control device as described in claim 1, wherein the heading control unit controls the ship to maintain the heading of the bow when the ship's position acquired by the ship's position information acquisition unit is within the first range.

3. A vessel control device according to claim 1 or 2, wherein the first range and the second range are circles having different radii.

4. The vessel control device according to claim 3, wherein the first range and the second range are each a circle centered on the same target position.

5. A ship control device as described in claim 1 or claim 2, further comprising a direction memory unit which stores the direction in which the ship is facing at the time the fixed position holding mode is entered, and the direction control unit controls the ship control device to maintain the direction stored in the direction memory unit when the position of the ship acquired by the ship position information acquisition unit is within the first range.

6. A ship control device as described in claim 5, wherein the orientation memory unit stores the orientation at the time when the ship returns to the target position by the thrust controlled by the output control unit, and the orientation control unit controls the orientation memory unit to maintain the orientation stored therein when the position of the ship acquired by the ship's own position information acquisition unit is within the first range.

7. A ship control device as described in claim 1 or claim 2, wherein the output control unit, when the ship's position is outside the second range, controls thrust so as to move the ship toward the target position by outputting forward thrust, and then controls so as not to generate thrust.

8. A ship control device as described in claim 7, which controls thrust to move the ship toward the target position by outputting forward thrust, and then maintains the heading of the bow when the ship is located inside the first range, or when the ship has passed the first range and is located in the second range.

9. A ship control device as described in claim 7, which controls thrust to move the ship towards the target position by outputting forward thrust, and then, if the ship does not reach the first range and is located in the second range, controls the heading of the bow to face the target position.

10. A ship control device as described in claim 1 or claim 2, further comprising a mode detection unit that detects when a fixed point holding mode has been entered, and when the output control unit receives throttle operation from a user, it terminates the fixed point holding mode and controls the output by giving priority to the throttle operation.

11. A ship comprising: an actuator that generates thrust for the ship and generates a moment on the ship; an operation unit that accepts input operations to operate the actuator; and a ship control device as described in claim 1 or claim 2 that controls the movement of the ship by operating the actuator.

12. A ship control device comprising: a ship position information acquisition unit that acquires the ship's position information; a direction control unit that controls the heading of the ship's bow to face the target position when the distance from a target position to the ship's position acquired by the ship position information acquisition unit is equal to or smaller than a threshold; and an output control unit that controls thrust to move the ship toward the target position when the distance from the ship's position acquired by the ship position information acquisition unit to the target position is greater than the threshold.

13. The vessel control device according to claim 12, wherein the threshold value is variable based on the position information of the vessel relative to the target position or an external factor.

14. A ship control method comprising: an area information acquisition process for acquiring area information identifying a first range close to a target position and a second range which is a range farther from the target position than the first range and close to the first range; a ship's own position information acquisition process for acquiring position information of the ship; a heading control process for controlling the heading of the bow so that the ship faces the target position, when the ship's own position acquired by the ship's own position information acquisition process is within the second range; and an output control process for controlling thrust so that the ship moves toward the target position, when the ship's own position acquired by the ship's own position information acquisition process is within a third range which is a range farther from the target position than the first range and the second range and close to the second range.

15. A program that causes a computer to execute the following steps: an area information acquisition step for acquiring area information identifying a first range close to a target position and a second range that is a range farther from the target position than the first range and close to the first range; a ship's own position information acquisition step for acquiring ship's position information; a heading control step for controlling the heading of the ship's bow to face the target position, if the ship's position acquired by the ship's own position information acquisition step is within the second range; and an output control step for controlling thrust so that the ship moves toward the target position, if the ship's position acquired by the ship's own position information acquisition step is within a third range that is farther from the target position than the first range and the second range and close to the second range.

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