Ship, ship control device, ship control method and program

Abstract

To achieve smooth shift from automatic navigation control of a ship to fixed point holding control of the ship while suppressing thrust of the ship from being generated in a direction against inertial force of the ship when shifting from the automatic navigation control of the ship to the fixed point holding control of the ship.SOLUTION: A ship comprises: an actuator which has a function of generating propulsive power of a ship and a function of causing the ship to generate moment; and a ship control device which activates the actuator. The ship control device can execute automatic navigation control of the ship and fixed point holding control of the ship. The ship control device includes a fixed point holding target position setting part which sets a fixed point holding target position that is a target position of the ship during execution of the fixed point holding control. When the ship control device executes the automatic navigation control of the ship and then executes the fixed point holding control of the ship, the fixed point holding target position setting part sets, as the fixed point holding target position which is different from an automatic navigation stop position that is a position as of when the ship stops the automatic navigation control.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a ship , ship control device, ship control method and program Regarding. [Background technology]

[0002] Conventionally, ships in which a controller executes auto-cruise control have been known (see, for example, Patent Document 1). In the technology described in Patent Document 1, a destination of the ship is set in auto-cruise control. Patent Document 1 also describes that auto-cruise control is stopped and fixed-point holding control is executed, and in the technology described in Patent Document 1, a target ship speed is set to zero in fixed-point holding control, and the propulsion unit is controlled to keep the ship at the destination. As in the technology described in Patent Document 1, when automatic navigation control (auto-cruise control) of a ship is executed and then fixed-position maintenance control of the ship is executed, at the time when the fixed-position maintenance control of the ship is started, the inertial force (speed) generated by the ship trying to stop while the automatic navigation control of the ship is being executed remains. Therefore, while the fixed-position maintenance control of the ship is being executed, the inertial force (speed) of the ship may cause the ship to pass its destination (the target position of the automatic navigation control and fixed-position maintenance control) due to the inertial force (speed) of the ship. In order to prevent the ship from passing the target position of the automatic navigation control and the fixed position control due to the ship's inertial force (speed) while the ship is being controlled to maintain its position, it has conventionally been necessary to generate a thrust force for the ship in a direction that counteracts the inertial force (speed), or to perform complex ship speed control at the end of the ship's automatic navigation control (auto-cruise control), as in the technology described in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-094945 Summary of the Invention [Problem to be solved by the invention]

[0004] In view of the above-mentioned problems, the present invention provides a ship that can smoothly transition from stopping the ship's navigation to maintaining a fixed position while suppressing the generation of a thrust of the ship in a direction that opposes the inertial force (speed) of the ship that occurs when transitioning from stopping the ship's navigation to maintaining a fixed position. , ship control device, ship control method and program The purpose is to provide. In detail, the present invention provides a vessel that can achieve a smooth transition from vessel stopping to vessel position keeping control, without the need to execute complex vessel speed control at the end of vessel stopping, as in the technology described in Patent Document 1, while suppressing the generation of a vessel's thrust in a direction that counteracts the vessel's inertial force (speed) that occurs when the vessel is transitioning from vessel stopping to vessel position keeping control. , ship control device, ship control method and program The purpose is to provide the following. [Means for solving the problem]

[0005] One aspect of the present invention is a vessel control system comprising an actuator having a function of generating a propulsive force for a vessel and a function of generating a moment on the vessel, and a vessel control device that operates the actuator, wherein the vessel control device is capable of executing fixed position maintenance control of the vessel, and the vessel control device comprises a fixed position maintenance target position setting unit that sets a fixed position maintenance target position that is a target position of the vessel while the fixed position maintenance control of the vessel is being executed, and when the vessel control device executes the fixed position maintenance control of the vessel by stopping the generation of the propulsive force of the vessel, the fixed position maintenance target position setting unit: At the time when it can be assumed that the movement of the vessel due to its speed has ended after the generation of the propulsive force of the vessel has stopped, a position different from the position of the vessel when the generation of the propulsive force of the vessel has stopped, and a position where it can be assumed that the movement of the vessel due to its speed has ended, is determined. , is a vessel that is set as the fixed point maintenance target position. One aspect of the present invention is a vessel control device that operates an actuator having a function of generating a propulsive force for a vessel and a function of generating a moment on the vessel, the vessel control device being capable of executing fixed position maintenance control of the vessel, the vessel control device including a fixed position maintenance target position setting unit that sets a fixed position maintenance target position that is a target position of the vessel while the fixed position maintenance control of the vessel is being executed, and when the vessel control device executes the fixed position maintenance control of the vessel by stopping the generation of the propulsive force of the vessel, the fixed position maintenance target position setting unit: At the time when it can be assumed that the movement of the vessel due to its speed has ended after the generation of the propulsive force of the vessel has stopped, a position different from the position of the vessel when the generation of the propulsive force of the vessel has stopped, and a position where it can be assumed that the movement of the vessel due to its speed has ended, is determined., and set the fixed point holding target position as the fixed point holding target position. One aspect of the present invention is a ship control method for a ship control device that operates an actuator having a function of generating a propulsive force for a ship and a function of generating a moment on the ship, the method comprising: a fixed point maintenance control step in which the ship control device executes fixed point maintenance control of the ship; and a fixed point maintenance target position setting step in which the ship control device sets a fixed point maintenance target position that is a target position of the ship while the ship control device is executing the fixed point maintenance control of the ship, and when generation of the propulsive force for the ship stops and the fixed point maintenance control step is executed, in the fixed point maintenance target position setting step: At the time when it can be estimated that the movement of the vessel due to its speed has ended after the generation of the propulsive force of the vessel has stopped, the position at which it can be estimated that the movement of the vessel due to its speed has ended is different from the position of the vessel at the time when the generation of the propulsive force of the vessel has stopped, and The fixed point holding target position is set as the fixed point holding target position. One aspect of the present invention is a program for causing a computer mounted on a vessel control device that operates an actuator having a function of generating a propulsive force for a vessel and a function of generating a moment on the vessel to execute a fixed point maintenance control step of performing fixed point maintenance control of the vessel, and a fixed point maintenance target position setting step of setting a fixed point maintenance target position that is a target position of the vessel during execution of the fixed point maintenance control of the vessel, wherein when generation of the propulsive force of the vessel stops and the fixed point maintenance control step is executed, the fixed point maintenance target position setting step At the time when it can be estimated that the movement of the vessel due to its speed has ended after the generation of the propulsive force of the vessel has stopped, the position at which it can be estimated that the movement of the vessel due to its speed has ended is different from the position of the vessel at the time when the generation of the propulsive force of the vessel has stopped, and The program is set as the fixed point maintenance target position. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a ship that can achieve a smooth transition from stopping the ship's navigation to maintaining a fixed position of the ship, while suppressing the generation of thrust of the ship in a direction that opposes the ship's inertial force (gain) that occurs when transitioning from automatic navigation control of the ship to maintaining a fixed position of the ship. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating an example of a ship to which a ship control device according to a first embodiment is applied. [Figure 2]3A to 3C are diagrams for explaining an example of the behavior of a ship when the ship control device of the first embodiment executes automatic navigation control and then executes fixed position maintenance control. [Figure 3] 5 is a flowchart illustrating an example of processing executed in a ship to which the ship control device of the first embodiment is applied. [Figure 4] 10 is a flowchart illustrating an example of processing executed in a ship to which a ship control device according to a second embodiment is applied. [Figure 5] FIG. 10 is a diagram illustrating an example of the behavior of a ship when the ship control device of the third embodiment executes automatic navigation control and then executes fixed position maintenance control. [Figure 6] FIG. 10 is a diagram showing an example of a ship to which a ship control device according to a fifth embodiment is applied. [Figure 7] FIG. 11 is a diagram for explaining an example of the behavior of a ship when the ship control device of the fifth embodiment executes automatic navigation control and then executes fixed position maintenance control. [Figure 8] 10 is a flowchart illustrating an example of processing executed in a vessel or the like to which a vessel control device according to a fifth embodiment is applied. [Figure 9] 13 is a flowchart illustrating an example of processing executed in a vessel or the like to which a vessel control device according to a sixth embodiment is applied. [Figure 10] FIG. 12 is a diagram showing an example of a ship to which a ship control device according to a seventh embodiment is applied. [Figure 11] 13 is a flowchart illustrating an example of processing executed in a vessel or the like to which a vessel control device according to a seventh embodiment is applied. [Figure 12] 13 is a flowchart illustrating an example of processing executed in a vessel or the like to which a vessel control device according to an eighth embodiment is applied. [Figure 13] FIG. 10 is a diagram for explaining the behavior of a ship in a comparative example when automatic navigation control is executed and then fixed position maintenance control is executed. [Figure 14]10 is a flowchart illustrating a process executed in a vessel of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0008] Before describing the embodiments of the ship, ship control device, ship control method, and program of the present invention, a ship control method of a comparative example will be described. Fig. 13 is a diagram for explaining the behavior of the ship R1 of the comparative example when automatic navigation control is executed and then fixed position maintenance control is executed. Fig. 14 is a flowchart for explaining the processing executed by the ship R1 of the comparative example. In the comparative example shown in FIGS. 13 and 14, in step SA in FIG. 14, the target position RTP (see FIG. 13(B)) for the automatic navigation control and fixed position keeping control is set by, for example, the operator of the ship R1. Next, in step SB, the ship R1 receives an automatic navigation start command from, for example, the operator of the ship R1, and the ship R1 starts automatic navigation (i.e., automatic navigation control of the ship R1 is started). As a result, as shown in Figure 13(A), the ship R1 moves toward the target position RTP of the automatic navigation control and fixed position keeping control. Next, in step SC, it is determined whether or not to stop automatic navigation. As shown in Figure 13(A), if the ship R1 has not reached the target position RTP of the automatic navigation control and fixed position keeping control, step SC is repeatedly executed. On the other hand, as shown in Figure 13(B), if the ship R1 has reached the target position RTP of the automatic navigation control and fixed position keeping control, automatic navigation is stopped (i.e., the propulsion force of the ship R1 is set to zero), and in step SD, fixed position keeping control of the ship R1 is started. In other words, the position of the ship R1 when the automatic navigation control of the ship R1 is stopped is the target position RTP of the automatic navigation control and fixed position keeping control.

[0009] According to the present invention, a ship can be provided that can smoothly transition from stopping the ship's navigation to fixed-position control while suppressing the generation of thrust of the ship in a direction that counteracts the ship's inertial force (speed) that occurs when transitioning from automatic navigation control of the ship to fixed-position control of the ship. , ship control device, ship control method and program can be provided.

[0010] Next, in step SE, it is determined whether or not to stop (terminate) the fixed position keeping control. As shown in Figure 13(D), if the vessel R1 has not yet returned to the target position RTP of the automatic navigation control and fixed position keeping control, step SE is repeatedly executed. On the other hand, as shown in Figure 13(E), if the vessel R1 has returned to the target position RTP of the automatic navigation control and fixed position keeping control, in step SF, the generation of the propulsive force of the vessel R1 is stopped (i.e., the propulsive force of the vessel R1 is set to zero).

[0011] First Embodiment A first embodiment of a ship, a ship control device, a ship control method, and a program according to the present invention will be described below. FIG. 1 is a diagram showing an example of a ship 1 to which a ship control device 1C according to the first embodiment is applied. The vessel control device 1C of the first embodiment can be applied to any type of vessel 1, such as a personal watercraft (PWC) having functions similar to those of the PWC (jet motorcycle) described in Figure 1 of Japanese Patent No. 5196649, or a vessel not equipped with a jet propulsion unit (for example, a vessel equipped with an outboard motor described in Japanese Patent No. 6198192, Japanese Patent Laid-Open Publication No. 2007-22284, etc., a vessel equipped with an inboard / outboard motor or an inboard engine, a large vessel equipped with a side thruster, etc.). In the example shown in FIG. 1, a ship 1 includes an actuator 1A, an operation unit 1B, a ship control device 1C, a ship position detection unit 1D, a ship heading detection unit 1E, and a ship speed detection unit 1F. The actuator 1A includes a rudder section 1A1 and a thrust generating section 1A2. The rudder section 1A1 has a function of generating a moment on the vessel 1. The thrust generating section 1A2 has a function of generating a propulsive force for the vessel 1. In an example where the vessel 1 is a PWC, the actuator 1A includes, for example, an engine, a nozzle, a deflector, a trim actuator, a bucket, a bucket actuator, etc., as described in FIG. 1 of JP 2019-171925 A.

[0012] In the example shown in FIG. 1, operation unit 1B accepts input of operations (e.g., instructions) by the operator of vessel 1. Operation unit 1B includes, for example, steering unit 1B1, throttle operation unit 1B2, automatic navigation target position setting unit 1B3, automatic navigation start instruction input unit 1B4, automatic navigation stop instruction input unit 1B5, and fixed position hold stop instruction input unit 1B6. Steering unit 1B1 accepts input operations by the operator to operate rudder unit 1A1. Throttle operation unit 1B2 accepts input operations by the operator to operate thrust generating unit 1A2. In an example where the vessel 1 is a PWC, the steering unit 1B1 and the throttle operating unit 1B2 are configured in a similar manner to, for example, the steering handle device described in Figure 1 of Patent Publication No. 5196649, or the steering unit described in Figure 1 of Patent Publication No. 2019-171925.

[0013] In the example shown in FIG. 1 , the automatic navigation target position setting unit 1B3 accepts the setting of a target position for automatic navigation control of the ship 1, for example, by the operator of the ship 1. The automatic navigation start instruction input unit 1B4 accepts the input of an instruction to start automatic navigation control of the ship 1, for example, by the operator of the ship 1. The automatic navigation stop instruction input unit 1B5 accepts the input of an instruction to stop automatic navigation control of the ship 1, for example, by the operator of the ship 1. The fixed position maintenance stop instruction input unit 1B6 accepts the input of an instruction to stop fixed position maintenance control of the ship 1, for example, by the operator of the ship 1. The ship control device 1C performs control such as activating the actuator 1A based on input operations from the operator of the ship 1 or the like received by the operation unit 1B. The ship control device 1C can perform automatic navigation control of the ship 1 and fixed position maintenance control of the ship 1. The ship control device 1C is equipped with an actuator control unit 1C1 and a fixed position maintenance target position setting unit 1C2. The actuator control unit 1C1 controls the actuator 1A. In other words, the actuator control unit 1C1 activates the actuator 1A. The fixed position maintenance target position setting unit 1C2 sets a fixed position maintenance target position, which is the target position of the ship 1 while fixed position maintenance control of the ship 1 is being executed.

[0014] The vessel position detection unit 1D detects the position of the vessel 1. The vessel position detection unit 1D includes, for example, a GPS (Global Positioning System) device. The GPS device calculates the position coordinates of the vessel 1 by receiving signals from a plurality of GPS satellites. The bow direction detection unit 1E detects the bow direction of the ship 1. The bow direction detection unit 1E includes, for example, a direction sensor. The direction sensor calculates the bow direction of the ship 1 by using, for example, geomagnetism. In another example, the orientation 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 sensor always points north. In yet another example, the orientation sensor may be a GPS compass that includes multiple GPS antennas and calculates the heading of the ship from the relative positions of the multiple GPS antennas.

[0015] 1, the vessel speed detection unit 1F detects the speed of the vessel 1. The vessel speed detection unit 1F may be, for example, a water pressure sensing type that detects the water speed of the vessel 1, or a GPS measurement type that detects the ground speed of the vessel 1.

[0016] Fig. 2 is a diagram illustrating an example of the behavior of the ship 1 when the ship control device 1C of the first embodiment executes automatic navigation control and then executes fixed position holding control. Fig. 3 is a flowchart illustrating an example of processing executed in the ship 1 to which the ship control device 1C of the first embodiment is applied. In the example shown in Figures 2 and 3, in step S11 of Figure 3, the automatic navigation target position setting unit 1B3 accepts the setting of an automatic navigation target position TP1 (see Figure 2(B)), which is the target position for automatic navigation control of the ship 1, for example, by the operator of the ship 1. Next, in step S12, the automatic navigation start instruction input unit 1B4 accepts input of an instruction to start automatic navigation control of the vessel 1, for example, from the operator of the vessel 1. As a result, the vessel control device 1C starts automatic navigation control of the vessel 1 (i.e., the vessel 1 starts automatic navigation), and the vessel 1 moves toward the automatic navigation target position TP1, as shown in FIG. 2(A). Next, in step S13, the ship control device 1C determines whether or not to stop the automatic navigation control of the ship 1. If the ship control device 1C determines not to stop the automatic navigation control of the ship 1 (more specifically, if the position of the ship 1 detected by the ship position detection unit 1D does not approximately match the automatic navigation target position TP1 (i.e., if the ship 1 has not reached the automatic navigation target position TP1) and the automatic navigation stop instruction input unit 1B5 has not received an input of an instruction to stop the automatic navigation control of the ship 1 from the operator of the ship 1 or the like), step S13 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the automatic navigation control of the ship 1 (more specifically, if the position of the ship 1 detected by the ship position detection unit 1D approximately matches the automatic navigation target position TP1 (i.e., if the ship 1 has reached the automatic navigation target position TP1) or if the automatic navigation stop instruction input unit 1B5 has received an input of an instruction to stop the automatic navigation control of the ship 1 from the operator of the ship 1 or the like), the process proceeds to step S14.

[0017] In the example shown in Figure 2(B), the position of the ship 1 detected by the ship position detection unit 1D roughly coincides with the automatic navigation target position TP1 (i.e., the ship 1 has reached the automatic navigation target position TP1), so the automatic navigation of the ship 1 is stopped (i.e., the ship control device 1C stops the automatic navigation control of the ship 1), and the ship control device 1C stops the generation of propulsion force for the ship 1 by the actuator 1A. In other words, the position of the ship 1 when the automatic navigation control of the ship 1 is stopped is the automatic navigation target position TP1. On the other hand, at the time shown in Figure 2(B), there remains an inertial force (starting speed) that was generated when the moving vessel 1 tried to stop during execution of the automatic navigation control of the vessel 1. Therefore, as shown in Figure 2(C), the vessel 1 continues to move due to the inertial force (starting speed) of the vessel 1. Therefore, in the example shown in Figures 2 and 3, in step S14, the vessel control device 1C monitors the speed of the vessel 1. More specifically, in step S14, the vessel control device 1C determines whether the speed of the vessel 1 detected by the vessel speed detection unit 1F has decreased to a first threshold value or less. If the speed of the vessel 1 has not decreased to a first threshold value or less (i.e., if the vessel 1 continues to move due to the inertial force (starting speed) of the vessel 1), step S14 is repeatedly executed. On the other hand, if the speed of the vessel 1 has decreased to a first threshold value or less (i.e., if it can be estimated that the movement of the vessel 1 due to the inertial force (starting speed) of the vessel 1 has ended), the process proceeds to step S15.

[0018] In step S15, the fixed point holding target position setting unit 1C2 sets the position of the ship 1 detected by the ship position detection unit 1D as the fixed point holding target position TP2 (see Figure 2 (C)), which is the target position of the ship 1 while the fixed point holding control of the ship 1 is being executed. Next, in step S16, the vessel control device 1C starts the fixed position keeping control of the vessel 1. Next, in step S17, the ship control device 1C determines whether or not to stop the fixed position holding control of the ship 1. If the ship control device 1C determines not to stop the fixed position holding control of the ship 1 (more specifically, if the fixed position holding stop instruction input unit 1B6 of the operation unit 1B has not received an input of an instruction to stop the fixed position holding control of the ship 1 from the operator of the ship 1 or the like), step S17 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the fixed position holding control of the ship 1 (more specifically, if the fixed position holding stop instruction input unit 1B6 of the operation unit 1B has received an input of an instruction to stop the fixed position holding control of the ship 1 from the operator of the ship 1 or the like), the process proceeds to step S18. In step S18, the ship control device 1C stops the fixed position holding control of the ship 1 and stops the generation of the propulsion force of the ship 1 by the actuator 1A (more specifically, the thrust of the ship 1 to hold the ship 1 at the fixed position holding target position TP2 (see Figure 2 (D)) against external disturbances such as wind and currents).

[0019] That is, in the example shown in Figures 1 to 3, when the ship control device 1C performs automatic navigation control of the ship 1 and then performs fixed point maintenance control of the ship 1, the fixed point maintenance target position setting unit 1C2 sets a position different from the position of the ship 1 when the automatic navigation control of the ship 1 is stopped (in the example shown in Figure 2, the automatic navigation target position TP1) as the fixed point maintenance target position TP2 (see Figure 2(C)). Therefore, in the example shown in Figures 1 to 3, the generation of thrust of the vessel 1 in a direction that resists the inertial force (speed) of the vessel 1 that occurs when transitioning from automatic navigation control of the vessel 1 to fixed position holding control of the vessel 1 is suppressed, and there is no need to perform complex vessel speed control at the end of the automatic navigation control of the vessel 1 as in the technology described in Patent Document 1, and a smooth transition from automatic navigation control of the vessel 1 to fixed position holding control of the vessel 1 can be achieved (in other words, the behavior of the vessel 1 can be made seamless and passengers on the vessel 1 can be given a sense of security). In the example shown in Figures 1 to 3, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C stops the actuator 1A from generating the propulsion force and thrust of the ship 1. However, in other examples, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C may cause the actuator 1A to generate a thrust in a direction that resists the inertial force generated by the stopping of the automatic navigation control of the ship 1. Furthermore, in the example shown in Figures 1 to 3, the position of the ship 1 detected by the ship position detection unit 1D when step S15 in Figure 3 is executed is set as the fixed point maintenance target position TP2, but in other examples, the position of the ship 1 at which the speed of the ship 1 becomes zero may be predicted based on the speed of the ship 1 when step S15 in Figure 3 is executed, and the predicted position may be set as the fixed point maintenance target position TP2.

[0020] Second Embodiment A second embodiment of the ship, ship control device, ship control method, and program according to the present invention will now be described. The vessel 1 of the second embodiment is configured similarly to the vessel 1 of the first embodiment described above, except for the points described below. Therefore, the vessel 1 of the second embodiment can achieve the same effects as the vessel 1 of the first embodiment described above, except for the points described below.

[0021] The ship 1 to which the ship control device 1C of the second embodiment is applied has the same configuration as the ship 1 to which the ship control device 1C of the first embodiment shown in FIG. 1 is applied.

[0022] FIG. 4 is a flowchart illustrating an example of processing executed in the boat 1 to which the boat control device 1C of the second embodiment is applied. In the example shown in Figure 4, in step S21, the automatic navigation target position setting unit 1B3 accepts the setting of the automatic navigation target position TP1 (see Figure 2(B)), which is the target position for automatic navigation control of the ship 1, for example, by the operator of the ship 1, similar to step S11 in Figure 3. Next, in step S22, the automatic navigation start instruction input unit 1B4 accepts input of an instruction to start automatic navigation control of the vessel 1, for example, from the operator of the vessel 1, as in step S12 of Fig. 3. As a result, the vessel control device 1C starts automatic navigation control of the vessel 1 (i.e., the vessel 1 starts automatic navigation), and the vessel 1 moves toward the automatic navigation target position TP1 as shown in Fig. 2(A). Next, in step S23, the ship control device 1C determines whether or not to stop the automatic navigation control of the ship 1, similar to step S13 in Fig. 3. If the ship control device 1C determines not to stop the automatic navigation control of the ship 1, step S23 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the automatic navigation control of the ship 1, the process proceeds to step S24.

[0023] As described above, in the example shown in Figure 2(B), the position of the ship 1 detected by the ship position detection unit 1D roughly coincides with the automatic navigation target position TP1, so automatic navigation of the ship 1 is stopped and the ship control device 1C stops the generation of propulsion force for the ship 1 by the actuator 1A. That is, the position of the vessel 1 when the automatic navigation control of the vessel 1 is stopped is the automatic navigation target position TP1. As described above, at the time shown in Fig. 2(B), there remains an inertial force (starting speed) that was generated when the moving vessel 1 tries to stop during execution of the automatic navigation control of the vessel 1. Therefore, as shown in Fig. 2(C), the vessel 1 continues to move due to the inertial force (starting speed) of the vessel 1. Therefore, in the examples shown in Figures 2 and 4, in step S24, the ship control device 1C monitors the elapsed time since the automatic navigation control of the ship 1 was stopped. More specifically, in step S24, the ship control device 1C determines whether the elapsed time since the automatic navigation control of the ship 1 was stopped is equal to or greater than a second threshold. If the elapsed time is not equal to or greater than the second threshold (i.e., it can be assumed that the ship 1 is continuing to move due to the inertial force (starting speed) of the ship 1), step S24 is repeatedly executed. On the other hand, if the elapsed time is equal to or greater than the second threshold (i.e., it can be assumed that the movement of the ship 1 due to the inertial force (starting speed) of the ship 1 has ended), the process proceeds to step S25.

[0024] In step S25, the fixed point holding target position setting unit 1C2 sets the position of the ship 1 detected by the ship position detection unit 1D as the fixed point holding target position TP2 (see Figure 2(C)), which is the target position of the ship 1 while the fixed point holding control of the ship 1 is being executed, similar to step S15 in Figure 3. Next, in step S26, the vessel control device 1C starts fixed position maintenance control of the vessel 1, similarly to step S16 in FIG. Next, in step S27, the ship control device 1C determines whether or not to stop the fixed position holding control of the ship 1, similar to step S17 in Fig. 3. If the ship control device 1C determines not to stop the fixed position holding control of the ship 1, step S27 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the fixed position holding control of the ship 1, the process proceeds to step S28. In step S28, the vessel control device 1C stops the fixed position holding control of the vessel 1, and stops the generation of thrust for the vessel 1 by the actuator 1A, similar to step S18 in FIG.

[0025] That is, in the example shown in Figures 2 and 4, when the ship control device 1C performs automatic navigation control of the ship 1 and then performs fixed point maintenance control of the ship 1, the fixed point maintenance target position setting unit 1C2 sets a position different from the position of the ship 1 when the automatic navigation control of the ship 1 is stopped (in the example shown in Figure 2, the automatic navigation target position TP1) as the fixed point maintenance target position TP2. Therefore, in the example shown in Figures 2 and 4, the generation of thrust of the vessel 1 in a direction that resists the inertial force (speed) of the vessel 1 that occurs when transitioning from automatic navigation control of the vessel 1 to fixed position holding control of the vessel 1 is suppressed, and there is no need to perform complex vessel speed control at the end of the automatic navigation control of the vessel 1 as in the technology described in Patent Document 1, and a smooth transition from automatic navigation control of the vessel 1 to fixed position holding control of the vessel 1 can be achieved (in other words, the behavior of the vessel 1 can be made seamless and passengers on the vessel 1 can be given a sense of security). In the examples shown in Figures 2 and 4, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C stops the actuator 1A from generating the propulsion and thrust of the ship 1. However, in other examples, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C may cause the actuator 1A to generate thrust in a direction that resists the inertial force generated by the stopping of the automatic navigation control of the ship 1.

[0026] <Third embodiment> A third embodiment of the ship, ship control device, ship control method, and program of the present invention will be described below. The boat 1 of the third embodiment is configured similarly to the boat 1 of the first embodiment described above, except for the points described below. Therefore, the boat 1 of the third embodiment can achieve the same effects as the boat 1 of the first embodiment described above, except for the points described below.

[0027] The ship 1 to which the ship control device 1C of the third embodiment is applied has the same configuration as the ship 1 to which the ship control device 1C of the first embodiment shown in FIG. 1 is applied.

[0028] FIG. 5 is a diagram illustrating an example of the behavior of the ship 1 when the ship control device 1C of the third embodiment executes automatic navigation control and then executes fixed position keeping control. In the boat 1 to which the boat control device 1C of the third embodiment is applied, the same process as that shown in FIG. 3 is executed. In the example shown in Figures 3 and 5, in step S11 of Figure 3, the automatic navigation target position setting unit 1B3 accepts the setting of an automatic navigation target position TP1 (see Figure 5(D)), which is the target position for automatic navigation control of the ship 1, for example, by the operator of the ship 1. Next, in step S12, the automatic navigation start instruction input unit 1B4 accepts input of an instruction to start automatic navigation control of the vessel 1, for example, from the operator of the vessel 1. As a result, the vessel control device 1C starts automatic navigation control of the vessel 1 (i.e., the vessel 1 starts automatic navigation), and the vessel 1 moves toward the automatic navigation target position TP1, as shown in Fig. 5(A). Next, in step S13, the ship control device 1C determines whether or not to stop the automatic navigation control of the ship 1. If the ship control device 1C determines not to stop the automatic navigation control of the ship 1 (more specifically, if the position of the ship 1 detected by the ship position detection unit 1D does not approximately match the automatic navigation target position TP1 (i.e., if the ship 1 has not reached the automatic navigation target position TP1) and the automatic navigation stop instruction input unit 1B5 has not received an input of an instruction to stop the automatic navigation control of the ship 1 from the operator of the ship 1 or the like), step S13 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the automatic navigation control of the ship 1 (more specifically, if the position of the ship 1 detected by the ship position detection unit 1D approximately matches the automatic navigation target position TP1 (i.e., if the ship 1 has reached the automatic navigation target position TP1) or if the automatic navigation stop instruction input unit 1B5 has received an input of an instruction to stop the automatic navigation control of the ship 1 from the operator of the ship 1 or the like), the process proceeds to step S14.

[0029] In the example shown in Figure 5(B), before the ship 1 reaches the automatic navigation target position TP1, the automatic navigation stop instruction input unit 1B5 receives an input of an instruction to stop the automatic navigation control of the ship 1 from the operator of the ship 1 or the like, so the automatic navigation of the ship 1 is stopped (i.e., the ship control device 1C stops the automatic navigation control of the ship 1), and the ship control device 1C stops the generation of propulsion force for the ship 1 by the actuator 1A. On the other hand, at the time shown in Figure 5(B), there remains an inertial force (starting speed) that was generated when the moving vessel 1 tried to stop during execution of the automatic navigation control of the vessel 1. Therefore, as shown in Figure 5(C), the vessel 1 continues to move due to the inertial force (starting speed) of the vessel 1. Therefore, in the examples shown in Figures 3 and 5, in step S14, the vessel control device 1C monitors the speed of the vessel 1. More specifically, in step S14, the vessel control device 1C determines whether the speed of the vessel 1 detected by the vessel speed detection unit 1F has decreased to a first threshold value or less. If the speed of the vessel 1 has not decreased to a first threshold value or less (i.e., if the vessel 1 continues to move due to the inertial force (starting speed) of the vessel 1), step S14 is repeatedly executed. On the other hand, if the speed of the vessel 1 has decreased to a first threshold value or less (i.e., if it can be estimated that the movement of the vessel 1 due to the inertial force (starting speed) of the vessel 1 has ended), the process proceeds to step S15.

[0030] In step S15, the fixed point holding target position setting unit 1C2 sets the position of the ship 1 detected by the ship position detection unit 1D as the fixed point holding target position TP2 (see Figure 5 (C)), which is the target position of the ship 1 while the fixed point holding control of the ship 1 is being executed. Next, in step S16, the vessel control device 1C starts the fixed position keeping control of the vessel 1. Next, in step S17, the ship control device 1C determines whether or not to stop the fixed position holding control of the ship 1. If the ship control device 1C determines not to stop the fixed position holding control of the ship 1 (more specifically, if the fixed position holding stop instruction input unit 1B6 of the operation unit 1B has not received an input of an instruction to stop the fixed position holding control of the ship 1 from the operator of the ship 1 or the like), step S17 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the fixed position holding control of the ship 1 (more specifically, if the fixed position holding stop instruction input unit 1B6 of the operation unit 1B has received an input of an instruction to stop the fixed position holding control of the ship 1 from the operator of the ship 1 or the like), the process proceeds to step S18. In step S18, the ship control device 1C stops the fixed position holding control of the ship 1 and stops the generation of the propulsion force of the ship 1 by the actuator 1A (more specifically, the thrust of the ship 1 to hold the ship 1 at the fixed position holding target position TP2 (see Figure 5(E)) against external disturbances such as wind and currents).

[0031] That is, in the example shown in Figures 3 and 5, when the ship control device 1C executes automatic navigation control of the ship 1 and then executes fixed-point maintenance control of the ship 1, the fixed-point maintenance target position setting unit 1C2 sets a position different from the position TPX of the ship 1 (see Figure 5(B)) when the automatic navigation control of the ship 1 is stopped as the fixed-point maintenance target position TP2 (see Figure 5(C)). In detail, the fixed-point maintenance target position setting unit 1C2 sets a position different from the position TPX of the ship 1 detected by the ship position detection unit 1D at the time when the automatic navigation stop instruction input unit 1B5 accepts input of an instruction to stop the automatic navigation control of the ship 1 by the operator of the ship 1 or the like as the fixed-point maintenance target position TP2. Therefore, in the examples shown in Figures 3 and 5, the generation of thrust of the vessel 1 in a direction that resists the inertial force (speed) of the vessel 1 that occurs when transitioning from automatic navigation control of the vessel 1 to fixed position holding control of the vessel 1 is suppressed, and there is no need to perform complex vessel speed control at the end of the automatic navigation control of the vessel 1 as in the technology described in Patent Document 1, and a smooth transition from automatic navigation control of the vessel 1 to fixed position holding control of the vessel 1 can be achieved (in other words, the behavior of the vessel 1 can be made seamless and passengers on the vessel 1 can be given a sense of security). In the examples shown in Figures 3 and 5, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C stops the actuator 1A from generating the propulsion and thrust of the ship 1. However, in other examples, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C may cause the actuator 1A to generate thrust in a direction that resists the inertial force generated by the stopping of the automatic navigation control of the ship 1.

[0032] <Fourth embodiment> A fourth embodiment of the ship, ship control device, ship control method, and program of the present invention will be described below. The boat 1 of the fourth embodiment is configured similarly to the boats 1 of the first and third embodiments described above, except for the points described below. Therefore, the boat 1 of the fourth embodiment can achieve the same effects as the boats 1 of the first and third embodiments described above, except for the points described below.

[0033] The ship 1 to which the ship control device 1C of the fourth embodiment is applied has the same configuration as the ship 1 to which the ship control device 1C of the first embodiment shown in FIG. 1 is applied. In the boat 1 to which the boat control device 1C of the fourth embodiment is applied, processing similar to the processing shown in FIG. 4 is executed.

[0034] In an example of a ship 1 to which the ship control device 1C of the fourth embodiment is applied, in step S21 of Figure 4, the automatic navigation target position setting unit 1B3 accepts the setting of an automatic navigation target position TP1 (see Figure 5 (D)), which is the target position for automatic navigation control of the ship 1, for example, by the operator of the ship 1. Next, in step S22 of Fig. 4, the automatic navigation start instruction input unit 1B4 accepts input of an instruction to start automatic navigation control of the vessel 1, for example, from the operator of the vessel 1. As a result, the vessel control device 1C starts automatic navigation control of the vessel 1 (i.e., the vessel 1 starts automatic navigation), and the vessel 1 moves toward the automatic navigation target position TP1, as shown in Fig. 5(A). 4, the ship control device 1C determines whether or not to stop the automatic navigation control of the ship 1. If the ship control device 1C determines not to stop the automatic navigation control of the ship 1, step S23 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the automatic navigation control of the ship 1, the process proceeds to step S24.

[0035] In the example shown in Figure 5(B), before the ship 1 reaches the automatic navigation target position TP1, the automatic navigation stop instruction input unit 1B5 receives an input of an instruction to stop the automatic navigation control of the ship 1 from the operator of the ship 1 or the like, so the automatic navigation of the ship 1 is stopped (i.e., the ship control device 1C stops the automatic navigation control of the ship 1), and the ship control device 1C stops the generation of propulsion force for the ship 1 by the actuator 1A. On the other hand, at the time shown in Figure 5(B), there remains an inertial force (starting speed) that was generated when the moving vessel 1 tried to stop during execution of the automatic navigation control of the vessel 1. Therefore, as shown in Figure 5(C), the vessel 1 continues to move due to the inertial force (starting speed) of the vessel 1. Therefore, in an example of a ship 1 to which the ship control device 1C of the fourth embodiment is applied, in step S24 of FIG. 4, the ship control device 1C monitors the elapsed time from when the automatic navigation stop instruction input unit 1B5 receives an input of an instruction to stop the automatic navigation control of the ship 1 from the operator of the ship 1 or the like (when the automatic navigation control is stopped). More specifically, in step S24 of FIG. 4, the ship control device 1C determines whether the elapsed time from when the automatic navigation stop instruction input unit 1B5 receives an input of an instruction to stop the automatic navigation control of the ship 1 from the operator of the ship 1 or the like is equal to or greater than a second threshold. If the elapsed time is not equal to or greater than the second threshold (i.e., it can be assumed that the ship 1 is continuing to move due to the inertial force (foot motion) of the ship 1), step S24 of FIG. 4 is repeatedly executed. On the other hand, if the elapsed time is equal to or greater than the second threshold (i.e., it can be assumed that the movement of the ship 1 due to the inertial force (foot motion) of the ship 1 has ended), the process proceeds to step S25 of FIG. 4.

[0036] In step S25 of Figure 4, the fixed point holding target position setting unit 1C2 sets the position of the ship 1 detected by the ship position detection unit 1D as the fixed point holding target position TP2 (see Figure 5 (C)), which is the target position of the ship 1 while the fixed point holding control of the ship 1 is being executed. Next, in step S26 of FIG. 4, the vessel control device 1C starts fixed position keeping control of the vessel 1. Next, in step S27 of Fig. 4, the ship control device 1C determines whether or not to stop the fixed position maintenance control of the ship 1. If the ship control device 1C determines not to stop the fixed position maintenance control of the ship 1, step S27 of Fig. 4 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the fixed position maintenance control of the ship 1, the process proceeds to step S28 of Fig. 4. In step S28 of FIG. 4, the vessel control device 1C stops the fixed position holding control of the vessel 1 and stops the generation of thrust for the vessel 1 by the actuator 1A.

[0037] That is, in an example of a ship 1 to which the ship control device 1C of the fourth embodiment is applied, when the ship control device 1C executes automatic navigation control of the ship 1 and then executes fixed position maintenance control of the ship 1, the fixed position maintenance target position setting unit 1C2 sets, as the fixed position maintenance target position TP2 (see FIG. 5(C)), a position different from the position TPX (see FIG. 5(B)) of the ship 1 at the time when the automatic navigation control of the ship 1 is stopped. In detail, the fixed position maintenance target position setting unit 1C2 sets, as the fixed position maintenance target position TP2, a position different from the position TPX of the ship 1 detected by the ship position detection unit 1D at the time when the automatic navigation stop instruction input unit 1B5 receives input of an instruction to stop the automatic navigation control of the ship 1 from the operator of the ship 1 or the like. Therefore, in an example of a ship 1 to which the ship control device 1C of the fourth embodiment is applied, the generation of thrust of the ship 1 in a direction that resists the inertial force (speed) of the ship 1 that occurs when transitioning from automatic navigation control of the ship 1 to fixed position holding control of the ship 1 is suppressed, while there is no need to perform complex ship speed control at the end of the automatic navigation control of the ship 1 as in the technology described in Patent Document 1, and a smooth transition from automatic navigation control of the ship 1 to fixed position holding control of the ship 1 can be achieved (in other words, the behavior of the ship 1 can be made seamless and passengers on board the ship 1 can be given a sense of security). In one example of a ship 1 to which the ship control device 1C of the fourth embodiment is applied, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C stops the actuator 1A from generating propulsion and thrust for the ship 1, but in another example, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C may cause the actuator 1A to generate thrust in a direction that resists the inertial force generated by the stopping of the automatic navigation control of the ship 1.

[0038] Fifth Embodiment A fifth embodiment of a ship, a ship control device, a ship control method, and a program according to the present invention will be described below. The boat 1 of the fifth embodiment is configured similarly to the boat 1 of the first embodiment described above, except for the points described below. Therefore, the boat 1 of the fifth embodiment can achieve the same effects as the boat 1 of the first embodiment described above, except for the points described below.

[0039] FIG. 6 is a diagram showing an example of a ship 1 to which a ship control device 1C according to the fifth embodiment is applied. In the example shown in Figure 6, the ship 1 is equipped with an actuator 1A, an operation unit 1B, a ship control device 1C, a ship position detection unit 1D, a bow direction detection unit 1E, a ship speed detection unit 1F, a water fall detection unit 1G, and a communication unit 1H. The actuator 1A is configured similarly to the actuator 1A shown in Figure 1. The operation unit 1B is configured similarly to the operation unit 1B shown in Figure 1. The ship control device 1C is configured similarly to the ship control device 1C shown in Figure 1. The ship position detection unit 1D is configured similarly to the ship position detection unit 1D shown in Figure 1. The bow direction detection unit 1E is configured similarly to the bow direction detection unit 1E shown in Figure 1. The ship speed detection unit 1F is configured similarly to the ship speed detection unit 1F shown in Figure 1.

[0040] The overboard detection unit 1G detects if a passenger on the boat 1 (such as the operator of the boat 1) has fallen overboard. The overboard detection unit 1G is configured in the same manner as the lanyard cord and switch described in, for example, paragraph 0002 of Japanese Patent No. 4205261. Specifically, one end of the lanyard cord is connected to a person to be detected for overboard (for example, a passenger on the boat 1, such as the operator of the boat 1). The other end of the lanyard cord is connected to a switch (not shown) arranged inside the boat 1. When the person to be detected falls overboard from the vessel 1, the other end of the lanyard cord comes off the switch, and the switch detects that the person to be detected has fallen overboard. As a result, the vessel control device 1C switches from a mode in which it executes control to operate the actuator 1A based on input operations from the operator of the vessel 1 or the like received by the operation unit 1B to a mode in which it executes automatic navigation control of the vessel 1.

[0041] The communication unit 1H communicates with the input device 2 carried by the person who is to be detected as having fallen into water by the water fall detection unit 1G. The input device 2 includes an input device position detection unit 2A, an operation unit 2B, and a communication unit 2C. The input device position detection unit 2A detects the position of the input device 2. The input device position detection unit 2A includes, for example, a GPS device. The GPS device calculates the position coordinates of the input device 2 by receiving signals from multiple GPS satellites. The operation unit 2B accepts a request to start automatic navigation control of the ship 1 (more specifically, automatic navigation control of the ship 1 that brings the ship 1 closer to the input device 2), for example, from a detected person who has fallen overboard from the ship 1 while carrying the input device 2. The communication unit 2C transmits information indicating the position of the input device 2 detected by the input device position detection unit 2A to the ship 1. The communication unit 1H of the ship 1 receives the information indicating the position of the input device 2 transmitted by the communication unit 2C. The position of the input device 2 detected by the input device position detection unit 2A is used for automatic navigation control of the ship 1 by the ship control device 1C (more specifically, for setting an automatic navigation target position TP1 (see FIG. 2(B) etc.) by the ship control device 1C). Furthermore, the communication unit 2C transmits to the ship 1 a request to start automatic navigation control of the ship 1 (more specifically, automatic navigation control of the ship 1 that brings the ship 1 closer to the input device 2) that has been received by the operation unit 2B. The communication unit 1H of the ship 1 receives the request to start automatic navigation control of the ship 1 transmitted by the communication unit 2C.

[0042] In the example shown in Figure 6, as described above, the distance between the ship 1 and the input device 2 is calculated based on the position of the ship 1 detected by the ship position detection unit 1D and the position of the input device 2 detected by the input device position detection unit 2A, and is used for automatic navigation control of the ship 1 by the ship control device 1C (more specifically, setting of the automatic navigation target position TP1 by the ship control device 1C). In another example, the ship 1 may be equipped with a distance detection unit such as a camera or radar, and the distance between the ship 1 and the input device 2 may be detected by the distance detection unit, which may be used for automatic navigation control of the ship 1 by the ship control device 1C (more specifically, for setting the automatic navigation target position TP1 by the ship control device 1C).

[0043] FIG. 7 is a diagram illustrating an example of the behavior of the ship 1 when the ship control device 1C of the fifth embodiment executes automatic navigation control and then executes fixed position maintenance control. In the example shown in FIG. 7, a person to be detected as having fallen into the water by the waterfall detection unit 1G (a person to be detected who is carrying the input device 2) falls into the water from the ship 1, which is moving downward in FIG. 7, at position P2 (see FIG. 7(A)). As a result, the input device position detection unit 2A of the input device 2 detects position P2 as the position of the input device 2. The communication unit 2C of the input device 2 transmits information indicating the position P2 of the input device 2 to the ship 1. Meanwhile, in the ship 1, the overboard detection unit 1G detects that the target person has fallen overboard, and as a result, the mode of the ship 1 switches to a mode in which the ship control device 1C executes automatic navigation control of the ship 1 (more specifically, automatic navigation control of the ship 1 that brings the ship 1 closer to the input device 2). The ship position detection unit 1D detects position P1 (see FIG. 7(E)) as the position of the ship 1. The ship control device 1C sets (calculates) an automatic navigation target position TP1 (see FIG. 7(C)), which is the target position for automatic navigation control (auto-return control) of the ship 1, based on information indicating the position P2 of the input device 2 received by the communication unit 1H and the position P1 of the ship 1 detected by the ship position detection unit 1D.

[0044] In addition, in the example shown in Figure 7, the operation unit 2B of the input device 2 receives a request to start automatic navigation control of the ship 1 from a detected person who has fallen overboard from the ship 1, and the communication unit 2C of the input device 2 transmits the request to start automatic navigation control of the ship 1 to the ship 1. As a result, the vessel control device 1C starts automatic navigation control of the vessel 1 (that is, the vessel 1 starts automatic navigation), and the vessel 1 moves toward the automatic navigation target position TP1 as shown in FIG. 7(D). In another example, when the overboard detection unit 1G detects that the person to be detected has fallen overboard, the ship control device 1C may automatically start automatic sailing control of the ship 1, without the operation unit 2B of the input device 2 having to accept a request from the person to be detected who has fallen overboard from the ship 1 to start automatic sailing control of the ship 1.

[0045] Next, in the example shown in Figure 7, when the ship 1 reaches the automatic navigation target position TP1 (see Figure 7(C)) (more specifically, when the position of the ship 1 detected by the ship position detection unit 1D roughly coincides with the automatic navigation target position TP1), the ship control device 1C stops the automatic navigation control of the ship 1 (more specifically, stops the generation of propulsive force for the ship 1 by the actuator 1A). In other words, the position of the ship 1 when the automatic navigation control of the ship 1 is stopped is the automatic navigation target position TP1. On the other hand, at the time shown in Figure 7(C), there remains an inertial force (starting speed) that was generated when the moving vessel 1 tried to stop during execution of the automatic navigation control of the vessel 1. Therefore, as shown in Figure 7(B), the vessel 1 continues to move due to the inertial force (starting speed) of the vessel 1.

[0046] Therefore, in the example shown in Figure 7, the ship control device 1C monitors the speed of the ship 1. In detail, when the speed of the ship 1 detected by the ship speed detection unit 1F drops below a first threshold (that is, when it can be assumed that the movement of the ship 1 due to the inertial force (starting speed) of the ship 1 has ended), the fixed point maintenance target position setting unit 1C2 of the ship control device 1C sets the position of the ship 1 detected by the ship position detection unit 1D as the fixed point maintenance target position TP2 (see Figure 7(B)), which is the target position of the ship 1 while fixed point maintenance control of the ship 1 is being executed. Furthermore, the ship control device 1C executes fixed point maintenance control of the ship 1.

[0047] FIG. 8 is a flowchart illustrating an example of processing executed in the vessel 1 to which the vessel control device 1C of the fifth embodiment is applied. In the example shown in Fig. 8, in step S3A, the ship control device 1C determines whether the waterfall detection unit 1G has detected the target person's fall into the water. If the ship control device 1C determines that the waterfall detection unit 1G has detected the target person's fall into the water, the process proceeds to step S3B. On the other hand, if the ship control device 1C determines that the waterfall detection unit 1G has not detected the target person's fall into the water, the routine shown in Fig. 8 ends. In step S3B, the communication unit 1H receives from the input device 2 information indicating the position P2 of the input device 2 detected by the input device position detection unit 2A of the input device 2 (see FIG. 7(A)). In step S3C, the vessel position detection unit 1D detects the position P1 of the vessel 1 (see FIG. 7(E)). Next, in step S31, the ship control device 1C sets (calculates) an automatic navigation target position TP1 (see Figure 7(C)), which is the target position for the automatic navigation control (auto-return control) of the ship 1, based on the information indicating the position P2 of the input device 2 received in step S3B and the position P1 of the ship 1 detected in step S3C.

[0048] Furthermore, in step S3D, the ship controlling device 1C determines whether the operation unit 2B of the input device 2 has received a request to start automatic navigation control of the ship 1 from the target person who has fallen overboard from the ship 1. More specifically, in step S3D, the ship controlling device 1C determines whether the communication unit 1H has received, from the input device 2, a request to start automatic navigation control of the ship 1 from the target person who has fallen overboard from the ship 1. If the operation unit 2B of the input device 2 has received a request to start automatic navigation control of the ship 1 from the target person who has fallen overboard from the ship 1 (in other words, if the communication unit 1H has received, from the input device 2, a request to start automatic navigation control of the ship 1 from the target person who has fallen overboard from the ship 1), the process proceeds to step S32. On the other hand, if the operation unit 2B of the input device 2 does not receive a request to start automatic navigation control of the vessel 1 from the person to be detected who has fallen overboard from the vessel 1 (i.e., if the communication unit 1H does not receive from the input device 2 a request to start automatic navigation control of the vessel 1 from the person to be detected who has fallen overboard from the vessel 1), the routine shown in Figure 8 is terminated. As described above, in another example, if it is determined in step S3A that the person to be detected has fallen into the water by the waterfall detection unit 1G, the process may proceed to step S32 without the communication unit 1H needing to receive from the input device 2 a request to start automatic navigation control of the ship 1 by the person to be detected who has fallen into the water from the ship 1.

[0049] In the example shown in Figure 8, in step S32, the ship control device 1C starts automatic navigation control of the ship 1 (i.e., the ship 1 starts automatic navigation), and the ship 1 moves toward the automatic navigation target position TP1, as shown in Figure 7 (D). Next, in step S33, the ship control device 1C determines whether or not to stop the automatic navigation control of the ship 1. If the ship control device 1C determines not to stop the automatic navigation control of the ship 1 (more specifically, if the position of the ship 1 detected by the ship position detection unit 1D does not approximately match the automatic navigation target position TP1 (see FIG. 7(C)) (i.e., if the ship 1 has not reached the automatic navigation target position TP1), and the operation unit 2B of the input device 2 has not received an input of an instruction to stop the automatic navigation control of the ship 1 from the target person who has fallen overboard from the ship 1), step S33 is repeatedly executed. On the other hand, if the ship control device 1C determines that the automatic navigation control of the ship 1 should be stopped (more specifically, if the position of the ship 1 detected by the ship position detection unit 1D roughly coincides with the automatic navigation target position TP1 (i.e., if the ship 1 reaches the automatic navigation target position TP1), or if the operation unit 2B of the input device 2 receives an input from the detected person who has fallen overboard from the ship 1 to stop the automatic navigation control of the ship 1), the process proceeds to step S34.

[0050] In step S34, the vessel control device 1C monitors the speed of the vessel 1. More specifically, in step S34, the vessel control device 1C determines whether the speed of the vessel 1 detected by the vessel speed detection unit 1F has decreased to a first threshold value or less. If the speed of the vessel 1 has not decreased to a first threshold value or less (i.e., if the vessel 1 continues to move due to the inertial force (starting speed) of the vessel 1), step S34 is repeatedly executed. On the other hand, if the speed of the vessel 1 has decreased to a first threshold value or less (i.e., if it can be estimated that the movement of the vessel 1 due to the inertial force (starting speed) of the vessel 1 has ended), the process proceeds to step S35.

[0051] In step S35, the fixed point holding target position setting unit 1C2 sets the position of the ship 1 detected by the ship position detection unit 1D as the fixed point holding target position TP2 (see Figure 7(B)), which is the target position of the ship 1 while the fixed point holding control of the ship 1 is being executed. Next, in step S36, the vessel control device 1C starts the fixed position keeping control of the vessel 1. Next, in step S37, the ship control device 1C determines whether or not to stop the fixed position maintenance control of the ship 1. If the ship control device 1C determines not to stop the fixed position maintenance control of the ship 1 (more specifically, if the communication unit 1H has not received from the input device 2 a request to stop the fixed position maintenance control of the ship 1 by the target person who has fallen overboard from the ship 1), step S37 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the fixed position maintenance control of the ship 1 (more specifically, if the communication unit 1H has received from the input device 2 a request to stop the fixed position maintenance control of the ship 1 by the target person who has fallen overboard from the ship 1), the process proceeds to step S38. In step S38, the ship control device 1C stops the fixed position holding control of the ship 1 and stops the generation of thrust for the ship 1 by the actuator 1A (more specifically, the thrust for the ship 1 to hold the ship 1 at the fixed position holding target position TP2 (see Figure 7(B)) against external disturbances such as wind and currents).

[0052] That is, in the examples shown in Figures 6 to 8, when the ship control device 1C performs automatic navigation control of the ship 1 and then performs fixed point maintenance control of the ship 1, the fixed point maintenance target position setting unit 1C2 sets a position different from the position of the ship 1 when the automatic navigation control of the ship 1 is stopped (in the example shown in Figure 7, the automatic navigation target position TP1) as the fixed point maintenance target position TP2 (see Figure 7(B)). Therefore, in the examples shown in Figures 6 to 8, the generation of thrust of the vessel 1 in a direction that resists the inertial force (speed) of the vessel 1 that occurs when transitioning from automatic navigation control of the vessel 1 to fixed position holding control of the vessel 1 is suppressed, and there is no need to perform complex vessel speed control at the end of the automatic navigation control of the vessel 1 as in the technology described in Patent Document 1, and a smooth transition from automatic navigation control of the vessel 1 to fixed position holding control of the vessel 1 can be achieved (in other words, the behavior of the vessel 1 is made seamless and a sense of security can be given to the detected person who has fallen overboard from the vessel 1). In the example shown in Figures 6 to 8, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C stops the actuator 1A from generating the propulsion force and thrust of the ship 1. However, in other examples, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C may cause the actuator 1A to generate a thrust in a direction that resists the inertial force generated by the stopping of the automatic navigation control of the ship 1.

[0053] Sixth Embodiment A sixth embodiment of a ship, a ship control device, a ship control method, and a program according to the present invention will now be described. The boat 1 of the sixth embodiment is configured similarly to the boat 1 of the fifth embodiment described above, except for the points described below. Therefore, the boat 1 of the sixth embodiment can achieve the same effects as the boat 1 of the fifth embodiment described above, except for the points described below.

[0054] The ship 1 to which the ship control device 1C of the sixth embodiment is applied has the same configuration as the ship 1 to which the ship control device 1C of the fifth embodiment shown in FIG. 6 is applied.

[0055] FIG. 9 is a flowchart illustrating an example of processing executed in the vessel 1 to which the vessel control device 1C of the sixth embodiment is applied. In the example shown in Fig. 9, in step S4A, the ship control device 1C determines whether the waterfall detection unit 1G has detected the target person's fall into the water, similar to step S3A in Fig. 8. If the ship control device 1C determines that the waterfall detection unit 1G has detected the target person's fall into the water, the process proceeds to step S4B. On the other hand, if the ship control device 1C determines that the waterfall detection unit 1G has not detected the target person's fall into the water, the routine shown in Fig. 9 ends. In step S4B, the communication unit 1H receives, from the input device 2, information indicating the position P2 (see FIG. 7A) of the input device 2 detected by the input device position detection unit 2A of the input device 2, similar to step S3B in FIG. In step S4C, the vessel position detection unit 1D detects the position P1 of the vessel 1 (see FIG. 7(E)) in the same manner as in step S3C of FIG. Next, in step S41, similar to step S31 in Figure 8, the ship control device 1C sets (calculates) an automatic navigation target position TP1 (see Figure 7(C)), which is the target position for the automatic navigation control (auto-return control) of the ship 1, based on the information indicating the position P2 of the input device 2 received in step S4B and the position P1 of the ship 1 detected in step S4C.

[0056] 8, the ship control device 1C determines whether the operation unit 2B of the input device 2 has received a request to start automatic navigation control of the ship 1 from the target person who has fallen overboard. If the operation unit 2B of the input device 2 has received a request to start automatic navigation control of the ship 1 from the target person who has fallen overboard, the process proceeds to step S42. On the other hand, if the operation unit 2B of the input device 2 has not received a request to start automatic navigation control of the ship 1 from the target person who has fallen overboard, the process ends the routine shown in FIG. As described above, in another example, if it is determined in step S4A that the person to be detected has fallen into the water by the waterfall detection unit 1G, the communication unit 1H may proceed to step S42 without having to receive from the input device 2 a request to start automatic navigation control of the ship 1 by the person to be detected who has fallen into the water from the ship 1.

[0057] In the example shown in Figure 9, in step S42, the ship control device 1C starts automatic navigation control of the ship 1 (i.e., the ship 1 starts automatic navigation), similar to step S32 in Figure 8, and the ship 1 moves toward the automatic navigation target position TP1, as shown in Figure 7(D). Next, in step S43, the ship control device 1C determines whether or not to stop the automatic navigation control of the ship 1, similar to step S33 in Fig. 8. If the ship control device 1C determines not to stop the automatic navigation control of the ship 1 (more specifically, if the position of the ship 1 detected by the ship position detection unit 1D does not approximately match the automatic navigation target position TP1 (see Fig. 7(C)) (that is, if the ship 1 has not reached the automatic navigation target position TP1), and the operation unit 2B of the input device 2 has not received an input of an instruction to stop the automatic navigation control of the ship 1 from the target person who has fallen overboard from the ship 1), step S43 is repeatedly executed. On the other hand, if the ship control device 1C determines that the automatic navigation control of the ship 1 should be stopped (more specifically, if the position of the ship 1 detected by the ship position detection unit 1D roughly coincides with the automatic navigation target position TP1 (i.e., if the ship 1 reaches the automatic navigation target position TP1), or if the operation unit 2B of the input device 2 receives an input from the detected person who has fallen overboard from the ship 1 instructing to stop the automatic navigation control of the ship 1), the process proceeds to step S44.

[0058] In step S44, the ship control device 1C monitors the elapsed time since the automatic navigation control of the ship 1 was stopped. More specifically, in step S44, the ship control device 1C determines whether the elapsed time since the automatic navigation control of the ship 1 was stopped is equal to or greater than a second threshold. If the elapsed time is not equal to or greater than the second threshold (i.e., it can be assumed that the ship 1 is continuing to move due to the inertial force (starting speed) of the ship 1), step S44 is repeatedly executed. On the other hand, if the elapsed time is equal to or greater than the second threshold (i.e., it can be assumed that the movement of the ship 1 due to the inertial force (starting speed) of the ship 1 has ended), the process proceeds to step S45.

[0059] In step S45, the fixed point holding target position setting unit 1C2 sets the position of the ship 1 detected by the ship position detection unit 1D as the fixed point holding target position TP2 (see Figure 7(B)), which is the target position of the ship 1 while the fixed point holding control of the ship 1 is being executed, similar to step S35 in Figure 8. Next, in step S46, the vessel control device 1C starts fixed position maintenance control of the vessel 1, similarly to step S36 in FIG. Next, in step S47, the ship control device 1C determines whether or not to stop the fixed position holding control of the ship 1, similar to step S37 in Fig. 8. If the ship control device 1C determines not to stop the fixed position holding control of the ship 1, step S47 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the fixed position holding control of the ship 1, the process proceeds to step S48. In step S48, the ship control device 1C stops the fixed position holding control of the ship 1, as in step S38 of Figure 8, and stops the generation of thrust for the ship 1 by the actuator 1A (more specifically, the thrust for the ship 1 to hold the ship 1 at the fixed position holding target position TP2 (see Figure 7(B)) against external disturbances such as wind and currents).

[0060] That is, in the examples shown in Figures 6 and 9, when the ship control device 1C performs automatic navigation control of the ship 1 and then performs fixed point maintenance control of the ship 1, the fixed point maintenance target position setting unit 1C2 sets a position different from the position of the ship 1 when the automatic navigation control of the ship 1 is stopped (in the example shown in Figure 7, the automatic navigation target position TP1) as the fixed point maintenance target position TP2 (see Figure 7(B)). Therefore, in the examples shown in Figures 6 and 9, the generation of thrust of the vessel 1 in a direction that resists the inertial force (speed) of the vessel 1 that occurs when transitioning from automatic navigation control of the vessel 1 to fixed position holding control of the vessel 1 is suppressed, and there is no need to perform complex vessel speed control at the end of the automatic navigation control of the vessel 1 as in the technology described in Patent Document 1, and a smooth transition from automatic navigation control of the vessel 1 to fixed position holding control of the vessel 1 can be achieved (in other words, the behavior of the vessel 1 is made seamless and a sense of security can be given to the detected person who has fallen overboard from the vessel 1). In the examples shown in Figures 6 and 9, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C stops the actuator 1A from generating the propulsion and thrust of the ship 1. However, in other examples, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C may cause the actuator 1A to generate thrust in a direction that resists the inertial force generated by the stopping of the automatic navigation control of the ship 1.

[0061] Seventh Embodiment A seventh embodiment of a ship, a ship control device, a ship control method, and a program according to the present invention will now be described. The boat 1 of the seventh embodiment is configured similarly to the boat 1 of the first embodiment described above, except for the points described below. Therefore, the boat 1 of the seventh embodiment can achieve the same effects as the boat 1 of the first embodiment described above, except for the points described below.

[0062] FIG. 10 is a diagram showing an example of a ship 1 to which a ship control device 1C according to the seventh embodiment is applied. In the example shown in Figure 10, the ship 1 is equipped with an actuator 1A, an operation unit 1B, a ship control device 1C, a ship position detection unit 1D, a bow direction detection unit 1E, a ship speed detection unit 1F, and a communication unit 1H. The actuator 1A is configured similarly to the actuator 1A shown in Figure 1. The operation unit 1B is configured similarly to the operation unit 1B shown in Figure 1. The ship control device 1C is configured similarly to the ship control device 1C shown in Figure 1. The ship position detection unit 1D is configured similarly to the ship position detection unit 1D shown in Figure 1. The bow direction detection unit 1E is configured similarly to the bow direction detection unit 1E shown in Figure 1. The ship speed detection unit 1F is configured similarly to the ship speed detection unit 1F shown in Figure 1.

[0063] The communication unit 1H communicates with the input device 2 carried by a vessel operator outside the vessel 1 (for example, a vessel operator of the vessel 1 who is at a pier or the like). The input device 2 includes an input device position detection unit 2A, an operation unit 2B, and a communication unit 2C. The input device position detection unit 2A detects the position of the input device 2. The input device position detection unit 2A includes, for example, a GPS device. The GPS device calculates the position coordinates of the input device 2 by receiving signals from multiple GPS satellites. The operation unit 2B accepts, for example, a request to start automatic navigation control of the vessel 1 (more specifically, automatic navigation control of the vessel 1 to bring the vessel 1 closer to the input device 2) from an operator outside the vessel 1 who is carrying the input device 2. The communication unit 2C transmits information indicating the position of the input device 2 detected by the input device position detection unit 2A to the ship 1. The communication unit 1H of the ship 1 receives the information indicating the position of the input device 2 transmitted by the communication unit 2C. The position of the input device 2 detected by the input device position detection unit 2A is used for automatic navigation control of the ship 1 by the ship control device 1C (more specifically, for setting an automatic navigation target position TP1 (see FIG. 2(B) etc.) by the ship control device 1C). Furthermore, the communication unit 2C transmits to the ship 1 a request to start automatic navigation control of the ship 1 (more specifically, automatic navigation control of the ship 1 that brings the ship 1 closer to the input device 2) that has been received by the operation unit 2B. The communication unit 1H of the ship 1 receives the request to start automatic navigation control of the ship 1 transmitted by the communication unit 2C.

[0064] In the example shown in Figure 10, the distance between the ship 1 and the input device 2 is calculated based on the position of the ship 1 detected by the ship position detection unit 1D and the position of the input device 2 detected by the input device position detection unit 2A, and is used for automatic navigation control of the ship 1 by the ship control device 1C (more specifically, setting of the automatic navigation target position TP1 by the ship control device 1C). In another example, the ship 1 may be equipped with a distance detection unit such as a camera or radar, and the distance between the ship 1 and the input device 2 may be detected by the distance detection unit, which may be used for automatic navigation control of the ship 1 by the ship control device 1C (more specifically, for setting the automatic navigation target position TP1 by the ship control device 1C).

[0065] FIG. 11 is a flowchart illustrating an example of processing executed in a vessel 1 to which a vessel control device 1C according to the seventh embodiment is applied. In the example shown in FIG. 11, in step S5A, the ship control device 1C determines whether the operation unit 2B of the input device 2 has accepted a request to start automatic sailing control of the ship 1 from a ship operator outside the ship 1. If the operation unit 2B of the input device 2 has accepted a request to start automatic sailing control of the ship 1 from a ship operator outside the ship 1 (in other words, if the communication unit 1H has received from the input device 2 a request to start automatic sailing control of the ship 1 from a ship operator outside the ship 1), the process proceeds to step S5B. On the other hand, if the operation unit 2B of the input device 2 has not accepted a request to start automatic sailing control of the ship 1 from a ship operator outside the ship 1 (in other words, if the communication unit 1H has not received from the input device 2 a request to start automatic sailing control of the ship 1 from a ship operator outside the ship 1), the routine shown in FIG. 11 is terminated. In step S5B, the communication unit 1H receives from the input device 2 information indicating the position of the input device 2 detected by the input device position detection unit 2A of the input device 2. In addition, in step S5C, the vessel position detection unit 1D detects the position of the vessel 1. Next, in step S51, the vessel control device 1C sets (calculates) an automatic navigation target position, which is a target position for automatic navigation control of the vessel 1, based on the information indicating the position of the input device 2 received in step S5B and the position of the vessel 1 detected in step S5C. Next, the process proceeds to step S52.

[0066] In step S52, the vessel control device 1C starts the automatic navigation control of the vessel 1 (that is, the vessel 1 starts automatic navigation), and the vessel 1 moves toward the automatic navigation target position. Next, in step S53, the ship control device 1C determines whether or not to stop the automatic navigation control of the ship 1. If the ship control device 1C determines not to stop the automatic navigation control of the ship 1 (more specifically, if the position of the ship 1 detected by the ship position detection unit 1D does not approximately match the automatic navigation target position (in other words, if the ship 1 has not reached the automatic navigation target position) and the operation unit 2B of the input device 2 has not received an input of an instruction to stop the automatic navigation control of the ship 1 from the operator outside the ship 1), step S53 is repeatedly executed. On the other hand, if the ship control device 1C determines that the automatic navigation control of the ship 1 should be stopped (more specifically, if the position of the ship 1 detected by the ship position detection unit 1D roughly coincides with the automatic navigation target position (i.e., if the ship 1 has reached the automatic navigation target position), or if the operation unit 2B of the input device 2 receives an input from an operator outside the ship 1 instructing to stop the automatic navigation control of the ship 1), the process proceeds to step S54.

[0067] In step S54, the vessel control device 1C monitors the speed of the vessel 1. More specifically, in step S54, the vessel control device 1C determines whether the speed of the vessel 1 detected by the vessel speed detection unit 1F has decreased to a first threshold value or less. If the speed of the vessel 1 has not decreased to a first threshold value or less (i.e., if the vessel 1 continues to move due to the inertial force (starting speed) of the vessel 1), step S54 is repeatedly executed. On the other hand, if the speed of the vessel 1 has decreased to a first threshold value or less (i.e., if it can be estimated that the movement of the vessel 1 due to the inertial force (starting speed) of the vessel 1 has ended), the process proceeds to step S55.

[0068] In step S55, the fixed point maintenance target position setting unit 1C2 sets the position of the ship 1 detected by the ship position detection unit 1D as the fixed point maintenance target position, which is the target position of the ship 1 while the fixed point maintenance control of the ship 1 is being executed. Next, in step S56, the vessel control device 1C starts the fixed position keeping control of the vessel 1. Next, in step S57, the ship control device 1C determines whether or not to stop the fixed position holding control of the ship 1. If the ship control device 1C determines not to stop the fixed position holding control of the ship 1 (more specifically, if the communication unit 1H has not received from the input device 2 a request from an operator outside the ship 1 to stop the fixed position holding control of the ship 1), step S57 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the fixed position holding control of the ship 1 (more specifically, if the communication unit 1H has received from the input device 2 a request from an operator outside the ship 1 to stop the fixed position holding control of the ship 1), the process proceeds to step S58. In step S58, the ship control device 1C stops the fixed position holding control of the ship 1 and stops the generation of thrust for the ship 1 by the actuator 1A (more specifically, the thrust for the ship 1 to hold the ship 1 at the fixed position holding target position against external disturbances such as wind and currents).

[0069] That is, in the example shown in Figures 10 and 11, when the ship control device 1C performs automatic navigation control of the ship 1 and then performs fixed point maintenance control of the ship 1, the fixed point maintenance target position setting unit 1C2 sets a position different from the position of the ship 1 when the automatic navigation control of the ship 1 is stopped as the fixed point maintenance target position. Therefore, in the example shown in Figures 10 and 11, the generation of thrust of the vessel 1 in a direction that resists the inertial force (speed) of the vessel 1 that occurs when transitioning from automatic navigation control of the vessel 1 to fixed position holding control of the vessel 1 is suppressed, and there is no need to perform complex vessel speed control at the end of the automatic navigation control of the vessel 1 as in the technology described in Patent Document 1, and a smooth transition from automatic navigation control of the vessel 1 to fixed position holding control of the vessel 1 can be achieved (in other words, the behavior of the vessel 1 can be made seamless). In the example shown in Figures 10 and 11, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C stops the actuator 1A from generating the propulsion and thrust of the ship 1, but in other examples, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C may cause the actuator 1A to generate thrust in a direction that resists the inertial force generated by the stopping of the automatic navigation control of the ship 1.

[0070] In another example of the processing executed in the vessel 1 to which the vessel control device 1C of the seventh embodiment is applied, processing similar to the processing shown in FIG. 3 described above is executed. 3, the operation unit 2B of the input device 2 accepts the setting of an automatic navigation target position TP1 (see FIG. 2(B)), which is a target position for automatic navigation control of the vessel 1, by an operator outside the vessel 1. The communication unit 2C of the input device 2 transmits information indicating the automatic navigation target position TP1 to the vessel 1. Next, in step S12, the operation unit 2B of the input device 2 accepts input of an instruction to start automatic navigation control of the vessel 1 from an operator outside the vessel 1. The communication unit 2C of the input device 2 transmits the instruction to start automatic navigation control of the vessel 1 to the vessel 1. As a result, the vessel control device 1C starts automatic navigation control of the vessel 1 (i.e., the vessel 1 starts automatic navigation), and the vessel 1 moves toward the automatic navigation target position TP1, as shown in FIG. 2(A). Next, in step S13, the ship control device 1C determines whether or not to stop the automatic navigation control of the ship 1. If the ship control device 1C determines not to stop the automatic navigation control of the ship 1 (more specifically, if the position of the ship 1 detected by the ship position detection unit 1D does not approximately match the automatic navigation target position TP1 (i.e., if the ship 1 has not reached the automatic navigation target position TP1) and the operation unit 2B of the input device 2 has not received an input from a ship operator outside the ship 1 to stop the automatic navigation control of the ship 1), step S13 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the automatic navigation control of the ship 1 (more specifically, if the position of the ship 1 detected by the ship position detection unit 1D approximately matches the automatic navigation target position TP1 (i.e., if the ship 1 has reached the automatic navigation target position TP1) or if the operation unit 2B of the input device 2 has received an input from a ship operator outside the ship 1 to stop the automatic navigation control of the ship 1), the process proceeds to step S14.

[0071] In step S14, the vessel control device 1C monitors the speed of the vessel 1. More specifically, in step S14, the vessel control device 1C determines whether the speed of the vessel 1 detected by the vessel speed detection unit 1F has decreased to a first threshold value or less. If the speed of the vessel 1 has not decreased to a first threshold value or less (i.e., if the vessel 1 continues to move due to the inertial force (starting speed) of the vessel 1), step S14 is repeatedly executed. On the other hand, if the speed of the vessel 1 has decreased to a first threshold value or less (i.e., if it can be estimated that the movement of the vessel 1 due to the inertial force (starting speed) of the vessel 1 has ended), the process proceeds to step S15.

[0072] In step S15, the fixed point holding target position setting unit 1C2 sets the position of the ship 1 detected by the ship position detection unit 1D as the fixed point holding target position TP2 (see Figure 2 (C)), which is the target position of the ship 1 while the fixed point holding control of the ship 1 is being executed. Next, in step S16, the vessel control device 1C starts the fixed position keeping control of the vessel 1. Next, in step S17, the ship control device 1C determines whether or not to stop the fixed position holding control of the ship 1. If the ship control device 1C determines not to stop the fixed position holding control of the ship 1 (more specifically, if the operation unit 2B of the input device 2 has not received an input from an operator outside the ship 1 to stop the fixed position holding control of the ship 1), step S17 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the fixed position holding control of the ship 1 (more specifically, if the operation unit 2B of the input device 2 has received an input from an operator outside the ship 1 to stop the fixed position holding control of the ship 1), the process proceeds to step S18. In step S18, the ship control device 1C stops the fixed position holding control of the ship 1 and stops the generation of the propulsion force of the ship 1 by the actuator 1A (more specifically, the thrust of the ship 1 to hold the ship 1 at the fixed position holding target position TP2 (see Figure 2 (D)) against external disturbances such as wind and currents).

[0073] Eighth Embodiment An eighth embodiment of a ship, a ship control device, a ship control method, and a program according to the present invention will now be described. The boat 1 of the eighth embodiment is configured similarly to the boat 1 of the seventh embodiment described above, except for the points described below. Therefore, the boat 1 of the eighth embodiment can achieve the same effects as the boat 1 of the seventh embodiment described above, except for the points described below.

[0074] The ship 1 to which the ship control device 1C of the eighth embodiment is applied is configured similarly to the ship 1 to which the ship control device 1C of the seventh embodiment shown in FIG. 10 is applied.

[0075] FIG. 12 is a flowchart illustrating an example of processing executed in the vessel 1 to which the vessel control device 1C of the eighth embodiment is applied. In the example shown in FIG. 12, in step S6A, the ship control device 1C determines whether the operation unit 2B of the input device 2 has accepted a request to start automatic sailing control of the ship 1 from a ship operator outside the ship 1, similar to step S5A in FIG. 11. If the operation unit 2B of the input device 2 has accepted a request to start automatic sailing control of the ship 1 from a ship operator outside the ship 1 (in other words, if the communication unit 1H has received from the input device 2 a request to start automatic sailing control of the ship 1 from a ship operator outside the ship 1), the process proceeds to step S6B. On the other hand, if the operation unit 2B of the input device 2 has not accepted a request to start automatic sailing control of the ship 1 from a ship operator outside the ship 1 (in other words, if the communication unit 1H has not received from the input device 2 a request to start automatic sailing control of the ship 1 from a ship operator outside the ship 1), the process ends the routine shown in FIG. 12. In step S6B, the communication unit 1H receives, from the input device 2, information indicating the position of the input device 2 detected by the input device position detection unit 2A of the input device 2, similar to step S5B in FIG. In step S6C, the vessel position detection unit 1D detects the position of the vessel 1 in the same manner as in step S5C of FIG. Next, in step S61, the vessel control device 1C sets (calculates) an automatic navigation target position, which is a target position for automatic navigation control of the vessel 1, based on the information indicating the position of the input device 2 received in step S6B and the position of the vessel 1 detected in step S6C, similar to step S51 in Fig. 11. Next, the process proceeds to step S62.

[0076] In step S62, the vessel control device 1C starts automatic navigation control of the vessel 1 (that is, the vessel 1 starts automatic navigation), similarly to step S52 in FIG. 11, and the vessel 1 moves toward the automatic navigation target position. Next, in step S63, the ship control device 1C determines whether or not to stop the automatic navigation control of the ship 1, similar to step S53 in Fig. 11. If the ship control device 1C determines not to stop the automatic navigation control of the ship 1 (more specifically, if the position of the ship 1 detected by the ship position detection unit 1D does not approximately match the automatic navigation target position (in other words, if the ship 1 has not reached the automatic navigation target position) and the operation unit 2B of the input device 2 has not received an input of an instruction to stop the automatic navigation control of the ship 1 from a ship operator outside the ship 1), step S63 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the automatic navigation control of the ship 1 (more specifically, if the position of the ship 1 detected by the ship position detection unit 1D approximately matches the automatic navigation target position (in other words, if the ship 1 has reached the automatic navigation target position) or if the operation unit 2B of the input device 2 has received an input of an instruction to stop the automatic navigation control of the ship 1 from a ship operator outside the ship 1), the process proceeds to step S64.

[0077] In step S64, the vessel control device 1C monitors the elapsed time since the automatic navigation control of the vessel 1 was stopped. More specifically, in step S64, the vessel control device 1C determines whether the elapsed time since the automatic navigation control of the vessel 1 was stopped is equal to or greater than a second threshold. If the elapsed time is not equal to or greater than the second threshold (i.e., it can be assumed that the vessel 1 is continuing to move due to the inertial force (headway) of the vessel 1), step S64 is repeatedly executed. On the other hand, if the elapsed time is equal to or greater than the second threshold (i.e., it can be assumed that the movement of the vessel 1 due to the inertial force (headway) of the vessel 1 has ended), the process proceeds to step S65.

[0078] In step S65, the fixed point maintenance target position setting unit 1C2 sets the position of the ship 1 detected by the ship position detection unit 1D as the fixed point maintenance target position, which is the target position of the ship 1 while the fixed point maintenance control of the ship 1 is being executed, similar to step S55 in Figure 11. Next, in step S66, the vessel control device 1C starts fixed position maintenance control of the vessel 1, similarly to step S56 in FIG. Next, in step S67, the ship control device 1C determines whether or not to stop the fixed position maintenance control of the ship 1, similar to step S57 in Fig. 11. If the ship control device 1C determines not to stop the fixed position maintenance control of the ship 1, step S67 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the fixed position maintenance control of the ship 1, the process proceeds to step S68. In step S68, the ship control device 1C stops the fixed position holding control of the ship 1, as in step S58 of Figure 11, and stops the generation of thrust for the ship 1 by the actuator 1A (more specifically, thrust for the ship 1 to hold the ship 1 at the fixed position holding target position against external disturbances such as wind and currents).

[0079] That is, in the example shown in Figures 10 and 12, when the ship control device 1C performs automatic navigation control of the ship 1 and then performs fixed point maintenance control of the ship 1, the fixed point maintenance target position setting unit 1C2 sets a position different from the position of the ship 1 when the automatic navigation control of the ship 1 is stopped as the fixed point maintenance target position. Therefore, in the example shown in Figures 10 and 12, the generation of thrust of the vessel 1 in a direction that resists the inertial force (speed) of the vessel 1 that occurs when transitioning from automatic navigation control of the vessel 1 to fixed position holding control of the vessel 1 is suppressed, and there is no need to perform complex vessel speed control at the end of the automatic navigation control of the vessel 1 as in the technology described in Patent Document 1, and a smooth transition from automatic navigation control of the vessel 1 to fixed position holding control of the vessel 1 can be achieved (in other words, the behavior of the vessel 1 can be made seamless). In the examples shown in Figures 10 and 12, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C stops the actuator 1A from generating the propulsion and thrust of the ship 1. However, in other examples, when the automatic navigation control of the ship 1 is stopped, the ship control device 1C may cause the actuator 1A to generate thrust in a direction that resists the inertial force generated by the stopping of the automatic navigation control of the ship 1.

[0080] In another example of the processing executed in the vessel 1 to which the vessel control device 1C of the eighth embodiment is applied, processing similar to the processing shown in FIG. 4 described above is executed. 4, the operation unit 2B of the input device 2 accepts the setting of an automatic navigation target position TP1 (see FIG. 2(B)), which is a target position for automatic navigation control of the vessel 1, by an operator outside the vessel 1. The communication unit 2C of the input device 2 transmits information indicating the automatic navigation target position TP1 to the vessel 1. Next, in step S22, the operation unit 2B of the input device 2 accepts input of an instruction to start automatic navigation control of the vessel 1 from an operator outside the vessel 1. The communication unit 2C of the input device 2 transmits the instruction to start automatic navigation control of the vessel 1 to the vessel 1. As a result, the vessel control device 1C starts automatic navigation control of the vessel 1 (i.e., the vessel 1 starts automatic navigation), and the vessel 1 moves toward the automatic navigation target position TP1, as shown in FIG. 2(A). Next, in step S23, the ship control device 1C determines whether or not to stop the automatic navigation control of the ship 1. If the ship control device 1C determines not to stop the automatic navigation control of the ship 1, step S23 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the automatic navigation control of the ship 1, the process proceeds to step S24.

[0081] In step S24, the ship control device 1C monitors the elapsed time since the automatic navigation control of the ship 1 was stopped. More specifically, in step S24, the ship control device 1C determines whether the elapsed time since the automatic navigation control of the ship 1 was stopped is equal to or greater than a second threshold. If the elapsed time is not equal to or greater than the second threshold (i.e., it can be assumed that the ship 1 is continuing to move due to the inertial force (starting speed) of the ship 1), step S24 is repeatedly executed. On the other hand, if the elapsed time is equal to or greater than the second threshold (i.e., it can be assumed that the movement of the ship 1 due to the inertial force (starting speed) of the ship 1 has ended), the process proceeds to step S25.

[0082] In step S25, the fixed point holding target position setting unit 1C2 sets the position of the ship 1 detected by the ship position detection unit 1D as the fixed point holding target position TP2 (see Figure 2 (C)), which is the target position of the ship 1 while the fixed point holding control of the ship 1 is being executed. Next, in step S26, the vessel control device 1C starts the fixed position keeping control of the vessel 1. Next, in step S27, the ship control device 1C determines whether or not to stop the fixed position holding control of the ship 1. If the ship control device 1C determines not to stop the fixed position holding control of the ship 1 (more specifically, if the operation unit 2B of the input device 2 has not received an input from an operator outside the ship 1 to stop the fixed position holding control of the ship 1), step S27 is repeatedly executed. On the other hand, if the ship control device 1C determines to stop the fixed position holding control of the ship 1 (more specifically, if the operation unit 2B of the input device 2 has received an input from an operator outside the ship 1 to stop the fixed position holding control of the ship 1), the process proceeds to step S28. In step S28, the vessel control device 1C stops the fixed position maintenance control of the vessel 1 and stops the generation of thrust for the vessel 1 by the actuator 1A.

[0083] Although the present invention has been described above using the embodiments, the present invention is not limited to these embodiments, and various modifications and substitutions can be made without departing from the spirit of the present invention. The configurations described in the above-described embodiments and examples may be combined.

[0084] Note that all or part of the functions of each unit of the vessel 1 in the above-described embodiment may be realized by recording a program for realizing these functions on a computer-readable recording medium, and reading 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. 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 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. [Explanation of symbols]

[0085] 1...ship, 1A...actuator, 1A1...rudder unit, 1A2...thrust generation unit, 1B...operation unit, 1B1...steering unit, 1B2...throttle operation unit, 1B3...automatic navigation target position setting unit, 1B4...automatic navigation start instruction input unit, 1B5...automatic navigation stop instruction input unit, 1C...ship control device, 1C1...actuator control unit, 1C2...fixed point holding target position setting unit, 1D...ship position detection unit, 1E...bow direction detection unit, 1F...ship speed detection unit, 1G...overboard detection unit, 1H...communication unit, 2...input device, 2A...input device position detection unit, 2B...operation unit, 2C...communication unit

Claims

1. an actuator having a function of generating a propulsive force for the vessel and a function of generating a moment on the vessel; a vessel control device that operates the actuator, the vessel control device is capable of performing fixed position keeping control of the vessel, the vessel control device includes a fixed point maintenance target position setting unit that sets a fixed point maintenance target position that is a target position of the vessel during execution of fixed point maintenance control of the vessel, When the vessel control device performs fixed position keeping control of the vessel by stopping generation of the propulsive force of the vessel, the fixed point maintenance target position setting unit sets, at a time when it can be estimated that the movement of the vessel due to its speed has ended after the generation of the propulsive force of the vessel has stopped, a position that is different from the position of the vessel when the generation of the propulsive force of the vessel has stopped, and at which it can be estimated that the movement of the vessel due to its speed has ended, as the fixed point maintenance target position; ship.

2. a ship position detection unit that detects the position of the ship; a vessel speed detection unit for detecting the vessel speed, the vessel control device stops the generation of the propulsive force of the vessel by the actuator; the fixed point maintenance target position setting unit sets the position of the ship detected by the ship position detection unit as the fixed point maintenance target position when the speed of the ship detected by the ship speed detection unit decreases to a first threshold value or less after the generation of the propulsive force has stopped; 2. The watercraft of claim 1.

3. a vessel position detection unit for detecting the position of the vessel; the vessel control device stops generation of the propulsive force of the vessel by the actuator when generation of the propulsive force of the vessel is stopped; the fixed point maintenance target position setting unit sets the position of the ship detected by the ship position detection unit as the fixed point maintenance target position when the elapsed time since the generation of the propulsive force has stopped is equal to or greater than a second threshold value.

2. The watercraft of claim 1.

4. 1. A vessel control device that operates an actuator having a function of generating a propulsive force for a vessel and a function of generating a moment on the vessel, the vessel control device is capable of performing fixed position keeping control of the vessel, the vessel control device includes a fixed point maintenance target position setting unit that sets a fixed point maintenance target position that is a target position of the vessel during execution of fixed point maintenance control of the vessel, When the vessel control device performs fixed position keeping control of the vessel by stopping generation of the propulsive force of the vessel, the fixed point maintenance target position setting unit sets, at a time when it can be estimated that the movement of the vessel due to its speed has ended after the generation of the propulsive force of the vessel has stopped, a position that is different from the position of the vessel when the generation of the propulsive force of the vessel has stopped, and at which it can be estimated that the movement of the vessel due to its speed has ended, as the fixed point maintenance target position; Ship control equipment.

5. 1. A ship control method for a ship control device that operates an actuator having a function of generating a propulsive force for a ship and a function of generating a moment on the ship, comprising: a fixed position holding control step in which the vessel control device executes fixed position holding control of the vessel; a fixed position maintenance target position setting step in which the vessel control device sets a fixed position maintenance target position that is a target position of the vessel while the vessel is executing fixed position maintenance control, When the generation of the propulsive force of the vessel is stopped and the fixed position maintenance control step is executed, In the fixed point maintenance target position setting step, at a time when it can be estimated that the movement of the vessel due to its speed has ended after the generation of the propulsive force of the vessel has stopped, a position different from the position of the vessel at the time when the generation of the propulsive force of the vessel has stopped and at which it can be estimated that the movement of the vessel due to its speed has ended is set as the fixed point maintenance target position. Ship control methods.

6. a computer mounted on a vessel control device that operates an actuator having a function of generating a propulsive force for a vessel and a function of generating a moment on the vessel; a fixed position keeping control step of performing fixed position keeping control of the ship; a fixed point maintenance target position setting step for setting a fixed point maintenance target position that is a target position of the vessel during execution of fixed point maintenance control of the vessel, When the generation of the propulsive force of the vessel is stopped and the fixed position maintenance control step is executed, In the fixed point maintenance target position setting step, at a time when it can be estimated that the movement of the vessel due to its speed has ended after the generation of the propulsive force of the vessel has stopped, a position different from the position of the vessel at the time when the generation of the propulsive force of the vessel has stopped and at which it can be estimated that the movement of the vessel due to its speed has ended is set as the fixed point maintenance target position. program.

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