Ship propulsion systems

Abstract

To improve responsiveness during turns and ensure navigation in accordance with the operator's intentions. [Solution] The ship's propulsion system comprises a power source, a propulsion unit that generates thrust by power transmitted from the power source, a plurality of propulsion machines provided on the left and right sides of the ship's center, a thrust direction changing device that changes the direction of the thrust of the plurality of propulsion machines, and a control unit that controls the thrust and thrust direction of the plurality of propulsion machines. When there is a difference between the instructed steering angle and the actual steering angle during a turn, the control unit performs turning assist control to generate a thrust balance corresponding to the difference. In turning assist control, the control unit acquires the instructed steering angle value input to the steering angle input unit, the actual steering angle value when the propulsion machine is actually turning, and the instructed thrust value input to the thrust input unit, calculates the steering thrust generated by the instructed thrust value when the direction of the propulsion machine's rudder reaches the instructed steering angle value, and calculates a correction thrust that generates the calculated steering thrust at the actual steering angle value.

Description

[Technical Field]

[0001] This disclosure relates to a ship propulsion system. [Background technology]

[0002] In recent years, efforts have become more active to provide access to sustainable transportation systems that also take into consideration vulnerable groups among transportation participants. Towards the development of sustainable transportation systems, research and development is underway to further improve the safety and convenience of transportation, for example, through ship driving assistance. Patent Document 1 discloses a ship handling system for controlling the operation of a ship equipped with two or more ship propulsion engines. Patent Document 1 discloses a technology that, when a turning control device fails, makes the ship turn without changing the direction of propulsion of the ship propulsion engines by making the output of the power sources of two or more ship propulsion engines different from each other based on a turning operation signal output from a turning operation device. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-172278 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, despite the existence of the fail-safe technology described above, there was room for improvement in improving responsiveness during turns when the ship's propulsion system is rotated during normal navigation, creating a difference in thrust between the left and right sides of the ship.

[0005] This disclosure aims to provide a ship propulsion system that improves responsiveness during turns and enables navigation in accordance with the operator's intentions. This disclosure will ultimately contribute to the development of sustainable transport systems. [Means for solving the problem]

[0006] As a means of solving the above-mentioned problems, the embodiments of this disclosure have the following configuration. (1) A propulsion system for a ship according to one aspect of the present disclosure comprises a power source, a propulsion unit that generates thrust by power transmitted from the power source, a plurality of propulsion machines provided on the left and right sides of the ship's center, a thrust direction changing device that changes the direction of the thrust of the plurality of propulsion machines, and a control unit that controls the thrust and thrust direction of the plurality of propulsion machines, wherein the control unit performs turning assist control to generate a thrust balance corresponding to the difference when there is a difference between the instructed steering angle and the actual steering angle when the ship is turning, and in the turning assist control, the control unit acquires an instructed steering angle value input to a steering angle input unit, an actual steering angle value when the propulsion machine is actually steering, and an instructed thrust value input to a thrust input unit, calculates the steering thrust generated by the instructed thrust value when the direction of the rudder of the propulsion machine reaches the instructed steering angle value, and calculates a correction thrust that generates the calculated steering thrust at the actual steering angle value. In general, thrust balance refers to the equal output of multiple propulsion systems, but in this application, it mainly refers to adjusting the thrust of each propulsion system so that a predetermined difference is created between the thrusts of the left and right propulsion systems.

[0007] (2) In the propulsion system of the ship described in (1) above, the control unit may perform the turning assist control when the instructed steering angle to the propulsion engine based on the instructed steering value is equal to or greater than the steering angle threshold.

[0008] (3) In the propulsion system of a ship described in (1) or (2) above, the control unit may perform the turning assist control when the difference between the instructed steering angle to the propulsion engine based on the instructed steering value and the actual steering angle at which the propulsion engine is actually steering is greater than or equal to an angle difference threshold.

[0009] (4) In the propulsion system of a ship described in any of (1) to (3) above, if the propulsion unit located on the inside of the ship's turning direction is designated as the inside propulsion unit and the propulsion unit located on the outside of the ship's turning direction is designated as the outside propulsion unit, the control unit may, in the turning assist control, reduce the thrust of the inside propulsion unit to less than a predetermined thrust and increase the thrust of the outside propulsion unit to a predetermined thrust or higher.

[0010] (5) In the propulsion system of a ship described in any of (1) to (4) above, the control unit may correct the steering instruction to the propulsion engine in the turning assist control so that it is greater than the instruction steering value.

[0011] (6) In the propulsion system of a ship described in any of (1) to (5) above, the control unit may, in the turning assist control, if the actual shift position of the propulsion machine and the corrective shift, which is a shift instruction for the corrective thrust, are different, match the actual shift position, which is the actual shift position, with the corrective shift, and then execute the turning assist control using the corrective thrust.

[0012] (7) In the propulsion system of a ship described in any of (1) to (6) above, the control unit may calculate the steering thrust in the turning assist control based on the angle formed by a reference line that is parallel to the centerline of the stern in a plan view and passes through the steering axis of the propulsion machine, and a straight line connecting the center of rotation of the ship and the steering axis.

[0013] (8) In the propulsion system of a ship described in any of (1) to (7) above, the control unit may calculate the steering thrust in the turning assist control based on the upper limit or lower limit of the thrust when the propulsion engine is actually turning. [Effects of the Invention]

[0014] According to the above embodiment, responsiveness during turns can be improved, and navigation can be carried out in accordance with the operator's intentions. [Brief explanation of the drawing]

[0015] [Figure 1] Plan view of a ship according to an embodiment. [Figure 2] Side view of a propulsion device according to an embodiment. [Figure 3] Block diagram of a ship propulsion system according to an embodiment. [Figure 4] Diagram showing a first example of yaw control. [Figure 5] Diagram showing a second example of yaw control. [Figure 6] Diagram showing a third example of yaw control. [Figure 7] Diagram showing user-intended vessel maneuvering together with relational expressions during turning of the ship. [Figure 8] Diagram showing an actual ship with steering delay together with relational expressions. [Figure 9] Diagram showing calculation formulas for balance thrust and the like. [Figure 10] State transition diagram of the propulsion system according to the embodiment. [Figure 11] Explanatory diagram of each condition of the propulsion system according to the embodiment. [Figure 12] Flowchart showing the main flow of turning assist control according to the embodiment. [Figure 13] Explanatory diagram of simulated large steering according to the embodiment. [Figure 14] Flowchart showing a flow for suppressing shift shock in the turning assist control according to the embodiment. [Figure 15] Timing chart for explaining a first example of the operation of the propulsion system according to the embodiment. [Figure 16] Timing chart for explaining a second example of the operation of the propulsion system according to the embodiment. [Figure 17] Diagram showing an example of a map for realizing the turning assist control according to the embodiment. [Mode for Carrying Out the Invention]

[0016] Embodiments of this disclosure will be described below with reference to the drawings. In the following description, expressions indicating relative or absolute arrangements such as "parallel," "orthogonal," "center," and "coaxial" will not only mean such arrangements strictly, but will also include states in which the relative arrangements are displaced by tolerances or angles and distances that allow the same function to be obtained. In this embodiment, "facing each other" is not limited to cases where the orthogonal directions (normal directions) of the two faces coincide with each other, but also includes cases where the orthogonal directions intersect. In the drawings used in the following description, the scale of each component has been appropriately changed in order to make each component recognizable.

[0017] <Ship> Figure 1 is a plan view of the vessel 1 according to the embodiment. As shown in Figure 1, the ship 1 comprises a hull 2, a plurality of propulsion units 3, a thrust direction changing device 4, and a control unit 5. The plurality of propulsion units 3, the thrust direction changing device 4, and the control unit 5 constitute the propulsion system 100 according to this embodiment.

[0018] In the following explanation, the directions of front, back, up, down, left, and right correspond to the orientation of vessel 1. In this case, arrow FR in the diagram indicates the front of vessel 1, arrow UP indicates the top of vessel 1, and arrow LH indicates the left of vessel 1. The center line CL indicates the center position of vessel 1 in the left-right direction (width direction).

[0019] <Propulsion machine> Multiple propulsion units 3 are provided on the hull 2. Propulsion units 3 are, for example, outboard motors. Propulsion units 3 include a left propulsion unit 3L provided on the left side (PORT side) of the stern, straddling the centerline CL, and a right propulsion unit 3R provided on the right side (STBD side) of the stern, straddling the centerline CL. The vessel 1 of this embodiment is a so-called twin-propulsion small vessel, with two propulsion units 3 (left propulsion unit 3L and right propulsion unit 3R) provided at both ends of the stern, straddling the centerline CL. In the following, unless it is necessary to distinguish between the propulsion units 3L and 3R, they will be described collectively as propulsion unit 3. Note that the left propulsion unit 3L and the right propulsion unit 3R are examples of outboard and inboard propulsion units.

[0020] Figure 2 is a side view of the propulsion machine 3 according to the embodiment. Figure 3 is a block diagram of the propulsion system 100 of the ship 1 according to the embodiment. Referring to Figures 2 and 3, the propulsion system 3 is, for example, an outboard motor. The propulsion system 3 comprises a casing 11, a power source 12, a drive shaft 13, a propulsion unit 14, and a shift switching mechanism 15.

[0021] The casing 11 is attached to a bracket 10 located at the stern via a rudder shaft 16 (swivel shaft) that extends vertically. The propulsion unit 3 is mounted to the hull 2 ​​so as to be rotatable around the rudder shaft 16 by the operation of a thrust direction changing device 4 (rudder actuator).

[0022] The power source 12 is, for example, an internal combustion engine. The power source 12 is housed in the upper part of the casing 11 with the crankshaft aligned vertically. The power (engine speed) of the power source 12 is set based on the opening of the throttle valve. The throttle valve is driven by the operation of the throttle actuator 18.

[0023] The drive shaft 13 transmits power generated by the power source 12 to the propulsion unit 14 via the shift switching mechanism 15. The drive shaft 13 extends vertically within the casing 11. The upper end of the drive shaft 13 is connected to the power source 12.

[0024] The propulsion unit 14 generates thrust by power transmitted from the power source 12. The propulsion unit 14 comprises a propeller shaft 21 and a propeller 22. The propeller shaft 21 is rotatably mounted at the lower end of the casing 11 around an axis along the longitudinal direction. The front end of the propeller shaft 21 is connected to the shift switching mechanism 15 within the casing 11. The propeller 22 is mounted at the rear end of the propeller shaft 21, protruding outward from the casing 11. The propeller 22 rotates integrally with the propeller shaft 21.

[0025] The shift switching mechanism 15 includes a drive gear 25, a forward gear 26, a reverse gear 27, and a clutch 28. The drive gear 25 is located at the lower end of the drive shaft 13. The drive gear 25 is rotatable integrally with the drive shaft 13.

[0026] The forward gear 26 and the reverse gear 27 are rotatably mounted on the propeller shaft 21, facing each other in the front-rear direction with the drive gear 25 in between. The forward gear 26 and the reverse gear 27 mesh with the drive gear 25. The forward gear 26 and the reverse gear 27 rotate in opposite directions as the drive gear 25 rotates.

[0027] The clutch 28 switches the power connection or disconnection state between the forward gear 26 or reverse gear 27 and the propeller shaft 21. The clutch 28 is rotatably mounted integrally with the propeller shaft 21 in the portion of the propeller shaft 21 located between the forward gear 26 and the reverse gear 27. The clutch 28 is mounted to be movable in the forward and backward direction along the propeller shaft 21 by the operation of the shift actuator 29.

[0028] The clutch 28, when engaged with the forward gear 26, can transmit the rotational force of the forward gear 26 to the propeller shaft 21 (forward position F). This causes the propeller 22 to rotate in the forward direction, thereby imparting forward thrust to the vessel 1. The clutch 28, when engaged with the reverse gear 27, can transmit the rotational force of the reverse gear 27 to the propeller shaft 21 (reverse position R). This causes the propeller 22 to rotate in the reverse direction, thereby imparting backward thrust to the vessel 1. On the other hand, when the clutch 28 is not engaged with either the forward gear 26 or the reverse gear 27, no rotational force is transmitted to the propeller shaft 21 (neutral position N). The positions where the clutch 28 engages with the forward gear 26 and the reverse gear 27 (forward position F, reverse position R, neutral position N) are the shift positions (actual shifts).

[0029] The thrust direction changing device 4 changes the direction of thrust from multiple propellers 3. The thrust direction changing device 4 may include, for example, an electric motor. Two propellers 3 (right propeller 3R and left propeller 3L) are mounted on the stern plate of the hull 2 ​​via brackets 10. The thrust direction changing device 4 is connected to the front end of the bracket 10. When the thrust direction changing device 4 is driven, the propellers 3 are steered around the steering axis 16 to a predetermined steering angle via a transmission mechanism such as gears or links (not shown). In this embodiment, a thrust direction changing device 4 is provided for each propeller 3.

[0030] Each thruster 3 and thrust direction change device 4 is electrically connected to a control unit 5 (integrated ECU). The control unit 5 controls the thrust (output) of the thrusters 3 and the direction of thrust (rudder angle) of the thrust direction change device 4.

[0031] <Steering Angle Input Section> The steering angle input unit 6 is located in the cockpit of the hull 2. The steering angle input unit 6 is, for example, a steering wheel that is rotatable in a reciprocating manner. The steering angle input unit 6 accepts user input when changing the course of the vessel 1 (hull 2). That is, the steering angle input unit 6 accepts input to change the direction (steering angle) of the propeller 3 around the steering axis 16. The steering angle is the angle of inclination of the propeller 3 with respect to the center line CL in a plan view. In this embodiment, the steering angle of the propeller 3 when the propeller shaft 21 is parallel to the center line CL in a plan view is set as the reference value (0°). The amount of operation due to the rotational operation of the steering angle input unit 6 is detected by the steering angle sensor 31. The steering angle sensor 31 outputs a detection signal based on the amount of operation of the steering angle input unit 6 as an instruction value to the control unit 5. Note that the steering angle input unit 6 may be a joystick, a steering wheel, or a switch on the control unit 9.

[0032] <Thrust Input Section> The thrust input unit 7 is located in the cockpit of the hull 2. The thrust input unit 7 is, for example, a throttle lever (accelerator lever). The thrust input unit 7 accepts user input when changing the thrust (required thrust) or the shift position (required shift position) of the propulsion unit 3. The thrust input unit 7 is configured to be able to move back and forth by rotation or sliding. The thrust input unit 7 can move back and forth within an operating area where three shift areas are arranged side by side: forward position F, neutral position N, and reverse position R.

[0033] In this embodiment, the propulsion system 3 is described using an outboard motor as an example, but the configuration is not limited to this. The propulsion system 3 may be an inboard motor, an inboard / outboard motor, a waterjet motor, etc., as long as the propulsion units are provided on both sides of the ship's center. For example, in the case of an inboard motor, the direction of the thrust of the propulsion system 3 may be changed by changing the direction of a separately provided rudder. For example, in the case of a waterjet motor, the direction of the thrust of the propulsion system 3 may be changed by changing the direction of the water flow. Alternatively, the propulsion system 3 may be configured by combining an outboard motor and side thrusters. In this case, the direction of the thrust of the propulsion system 3 may be changed by the ratio of the thrusts of the outboard motor and the side thrusters.

[0034] In the vessel 1, the requested shift position can be set according to the position of the thrust input unit 7 relative to the operating area. That is, if the thrust input unit 7 is located in the shift area of ​​the forward position F, the control unit 5 can be requested to set the shift position to the forward position F. If the thrust input unit 7 is located in the shift area of ​​the neutral position N, the control unit 5 can be requested to set the shift position to the neutral position N. If the thrust input unit 7 is located in the shift area of ​​the reverse position R, the control unit 5 can be requested to set the shift position to the reverse position R.

[0035] In the vessel 1, the required thrust can be set according to the position of the thrust input unit 7 relative to the operating area. That is, when the thrust input unit 7 is located in the shift area of ​​the neutral position N, the thrust can be requested to be zero from the control unit 5. When the thrust input unit 7 is set in the shift area of ​​the forward position F or the reverse position R, the thrust can be requested to increase in the direction of travel as it moves away from the shift area of ​​the neutral position N. The position of the thrust input unit 7 (lever opening LE) is detected by the position sensor 32. The position sensor 32 outputs a detection signal based on the position of the thrust input unit 7 (lever opening LE) to the control unit 5.

[0036] <Ship speed sensor> The ship speed sensor 8 detects the speed (ship speed) V of the vessel 1. The ship speed sensor 8 receives positioning signals from positioning satellites such as GPS (Global Positioning System), measures the absolute position (latitude, longitude) of the vessel 1 based on the received positioning signals, and calculates the ship speed (ship speed relative to land) V based on the time-series positioning results. The ship speed sensor 8 may also be an acoustic or electromagnetic sensor that detects the ship speed (ship speed relative to water) V of the vessel 1. The ship speed sensor 8 may also estimate the ship speed V based on the engine speed.

[0037] <Operation section> The control unit 9 is located in the cockpit of the hull 2. The control unit 9 receives various operations on the vessel 1. The control unit 9 is configured to be manually operated by the user, for example, as an MFD (Multi Function Display). The control unit 9 may also be an external device such as a portable terminal connected to the vessel 1 by wire or wireless connection.

[0038] <Department Head> The control unit 5 comprehensively controls the operation of the ship 1 (propulsion unit 3). The control unit 5 is one or more electronic control units provided by the ship 1. The control unit 5 is realized, for example, by a hardware processor such as a CPU (Central Processing Unit) executing a program (software) stored in ROM (Read Only Memory) or RAM (Random Access Memory). Some or all of these components may be realized by hardware (including circuitry) such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), GPU (Graphics Processing Unit), or SOC (System On Chip), or by the cooperation of software and hardware.

[0039] The control unit 5 includes a storage unit 50, an acquisition unit 51, a determination unit 52, and a drive processing unit 53. The memory unit 50 is composed of, for example, a ROM. The memory unit 50 stores programs and various data necessary for the navigation of the ship 1, such as a normal operation mode and a turning assist operation mode. The acquisition unit 51 is composed of, for example, RAM. The acquisition unit 51 acquires the detection results of various sensors. Detection signals from other sensors that detect the operating status of the thruster 3 are also acquired by the acquisition unit 51, but these are not shown in the illustration or described. The determination unit 52 is configured, for example, by a CPU. The determination unit 52 determines the state of the ship 1 based on the information obtained by the acquisition unit 51 and the information stored in the storage unit 50. The drive processing unit 53 is composed of, for example, a CPU. The drive processing unit 53 controls the operation of various actuators based on the determination result from the determination unit 52 and the information stored in the storage unit 50 and the acquisition unit 51.

[0040] The control unit 5 controls the thrust and thrust direction of the multiple propulsion units 3. In this embodiment, when there is a difference between the instructed steering and the actual steering during a turn of the ship 1, the control unit 5 performs turning assist control to generate a thrust balance corresponding to the difference.

[0041] <Example of yaw control> Figure 4 shows the first example of yaw control. As shown in Figure 4, in the first example of yaw control, the user does not perform rotational operation on the steering angle input unit 6 (e.g., the steering wheel). The first example of yaw control corresponds to when the ship 1 is moving forward (straight ahead).

[0042] Figure 5 shows a second example of yaw control. As shown in Figure 5, the second example of yaw control is an example of control to obtain a thrust balance that speeds up rudder response. In the second example of yaw control, a thrust balance is created in which the thrust of the outer thruster is greater than the thrust of the inner thruster at the same time as the user starts rotating the rudder angle input unit 6, so that a turning force is generated in the yaw direction from the start of the turn. In the second example of yaw control, the direction of thrust is changed while maintaining the thrust balance during the turn of the vessel 1, so the rudder angle is given as intended by the user.

[0043] Figure 6 shows a third example of yaw control. As shown in Figure 6, the third example of yaw control is an example of control to obtain a thrust balance that allows for tighter turns compared to the second example of yaw control shown in Figure 5. In the third example of yaw control, the user maintains the rotation operation of the rudder angle input unit 6, thereby maintaining the rudder angle and the turning attitude of the vessel 1. In the third example of yaw control, the rudder angle is maintained and a shift response is performed. In the third example of yaw control, as a shift response, the shift position of the right thruster 3R is kept in the forward position, and the shift position of the left thruster 3L is changed to the reverse position.

[0044] <An example of turning assist control> Figure 7 shows the user's intended maneuvering of vessel 1 during a turn, along with the relevant equations. Figure 8 shows an actual vessel with a steering delay, along with the relevant equations. Figure 9 shows the formula for calculating the balance thrust, etc.

[0045] Referring to Figures 7 to 9, the turning assist control generates a thrust balance corresponding to the difference between the instructed steering angle and the actual steering angle when the vessel 1 is turning. Specifically, the thrust is controlled according to the difference between the instructed steering angle (see Figure 7), which is input from the user, and the actual steering angle (see Figure 8), which is the angle that the propulsion system 3 is actually turning. This results in a steering thrust equivalent to the theoretical value of the steering thrust from the user input.

[0046] In Figure 7, when the user intends to steer the ship, the Port steering angle (α) corresponds to the angle between a reference line in a plan view that is parallel to the centerline of the stern and passes through the steering axis of the left thruster 3L (PORT side), and a straight line corresponding to the direction of the user's intended steering. The Port thrust (F) can be estimated from the position of the thrust input unit 7 (lever opening LE), although details will be described later. The center of gravity position (θ) as seen from Port corresponds to the angle between a reference line in a plan view that is parallel to the centerline of the stern and passes through the steering axis of the left thruster 3L, and a straight line connecting the center of gravity position of the ship 1 and the steering axis. The stab steering angle (α) corresponds to the angle between a reference line, which is parallel to the stern centerline and passes through the steering axis of the right propulsion engine 3R (STBD side) in a plan view, and a straight line corresponding to the direction of the ship's intended steering by the user. The stab thrust (F) is proportional to the throttle valve opening (THB). The center of gravity position (-θ) as seen from the stab corresponds to the angle between a reference line, which is parallel to the stern centerline and passes through the steering axis of the right propulsion engine 3R in a plan view, and a straight line connecting the center of gravity position of ship 1 and the steering axis. The angle (α+θ) between the port and the center of gravity corresponds to the sum of the port's directed steering angle (α) and the center of gravity's position as seen from the port (θ). The angle (α-θ) between the stab and the center of gravity corresponds to the sum of the stab's directed steering angle (α) and the center of gravity's position as seen from the stab (-θ). The force used for turning (T α This corresponds to the sum of the rotational component of the port thrust (F) and the rotational component of the stab thrust (F).

[0047] In Figure 8, for a real ship experiencing a steering delay, the actual port steering angle (β) corresponds to the angle between a reference line parallel to the stern centerline in a plan view and passing through the steering axis of the left thruster 3L (port side), and a straight line corresponding to the orientation of the real ship experiencing the steering delay. Port thrust (F β-port ) is proportional to the throttle valve opening (THB). The center of gravity position (θ) as seen from port corresponds to the angle between a reference line parallel to the centerline of the stern in a plan view and passing through the steering axis of the left propulsion engine 3L, and a straight line connecting the center of gravity position of ship 1 and the steering axis. The Stab actual steering angle (β) corresponds to the angle between a reference line parallel to the centerline of the stern in a plan view and passing through the steering axis of the right thruster 3R (STBD side), and a straight line corresponding to the direction of the actual ship which is lagging behind in steering. Stab thrust (F β-stab ) is proportional to the throttle valve opening (THB). The center of gravity position (-θ) as seen from the stab corresponds to the angle between a reference line parallel to the centerline of the stern in a plan view and passing through the steering axis of the right propulsion engine 3R, and a straight line connecting the center of gravity position of ship 1 and the steering axis. The angle (β+θ) between the port and the center of gravity corresponds to the sum of the actual steering angle of the port (β) and the position of the center of gravity as seen from the port (θ). The angle (β-θ) between the stab and the center of gravity corresponds to the sum of the actual steering angle of the stab (β) and the position of the center of gravity as seen from the stab (-θ). The force used for turning (T β ) is Port thrust (F β-port ) the rotational component and the Stab thrust (F β-stab This corresponds to the sum of the component in the direction of rotation and the component in the direction of rotation.

[0048] When constrained to equalize the sum of the left and right thrusts so that the ship speeds are equal, the port thrust (F) in a real ship with a steering delay is determined. β-port ) is the value obtained by adding the thrust difference (ΔF) to the port thrust (F) in the ship's intended maneuver. Also, the stab thrust (F) in a real ship with steering lag. β-stab This value is obtained by subtracting the thrust difference (ΔF) from the stab thrust (F) in the user's intended maneuver.

[0049] The force used for turning in the vessel maneuvering intended by the user(T α ) and the force used for turning on the actual vessel with steering lag(T β ), the balance thrust (ΔF) when they are equal to each other is represented by Formula (1) shown in Figure 9. The Port thrust (F on the actual vessel with steering lag β-port ) is represented by Formula (2) shown in Figure 9. The Stab thrust (F on the actual vessel with steering lag β-stab ) is represented by Formula (3) shown in Figure 9.

[0050] Note that the larger the difference between the instructed steering and the actual steering, the larger ΔF becomes. Also, the smaller θ becomes, the larger ΔF becomes. In other words, the farther the center of gravity position is from the propulsion unit 3 in plan view (the more forward it is positioned), the larger ΔF becomes.

[0051] For example, in the vessel maneuvering intended by the user, the user assumes the turning force generated when the steering wheel is fully turned to achieve full steering. On the other hand, since there is a steering lag on the actual vessel, the vessel is not steered much. Therefore, the thrust difference (ΔF) between the left and right turning thrusts is calculated in order to generate the turning force that occurs when the turning intended by the user is completed. If the engine speed is increased to enhance the turning force, the vessel speed will increase, so only one of the left and right propulsion units 3 is reduced in thrust. Alternatively, only one of the left and right propulsion units 3 is put into reverse to increase the thrust. In the above example, while keeping the sum of the left and right thrusts unchanged, the thrust difference (ΔF) is added to one side, and the thrust difference (ΔF) is subtracted from the other side. Then, the thrust difference (ΔF) is determined such that the force used for turning on the actual vessel generates the same thrust as the turning force assumed for the full steering intended by the user.

[0052] Furthermore, in turning assist control, the steering thrust is not limited to calculating it based on the angle between a reference line that is parallel to the centerline of the stern in a plan view and passes through the steering axis of the left propulsion engine 3L, and a straight line connecting the center of gravity of the ship 1 and the steering axis. For example, in turning assist control, the control unit 5 may calculate the steering thrust based on the angle between a reference line that is parallel to the centerline CL of the stern in a plan view and passes through the steering axis 16 of the propulsion engine 3, and a straight line connecting the turning point of the ship 1 and the steering axis 16. The turning point is the point where the original course and the changed course intersect within the straight distance from when the ship 1 turns until the change of course begins (in other words, the point where the original course intersects with the bow-stern line at the start of the change of course).

[0053] Figure 10 is a state transition diagram of the propulsion system 100 according to the embodiment. Figure 11 is an explanatory diagram of each condition of the propulsion system 100 according to the embodiment. Referring to Figures 10 and 11, the propulsion system 100 switches between a normal DBW (Drive by wire) mode and an assist turn mode based on conditions 1 and 2.

[0054] The normal operation mode is a mode in which the vessel 1 is operated in a speed range other than the slow speed range (the normal speed range which is faster than the slow speed upper threshold Vth). The slow speed upper threshold Vth may be set to, for example, 10 km / h. The turning assist driving mode is a mode that allows the vessel 1 to navigate within a predetermined speed range (for example, approximately 2 km / h to 8 km / h) below the slow speed upper threshold Vth.

[0055] Condition 1 is that all of the following conditions (1-1) through (1-3) are met. (1-1) The ship's speed must be below the slow speed upper threshold Vth. (1-2) The turn switch must be in the enabled position. (1-3) The initialization process of the propulsion system must be completed.

[0056] Condition 2 is that either condition (2-1) or (2-2) below is met (Condition 2A), and condition (2-3) below is met (Condition 2B), or both conditions (Conditions 2A and 2B) are met. (2-1) The ship's speed is greater than the slow speed upper threshold Vth. (2-2) The turn switch is in a disabled state. (2-3) The initialization process of the propulsion system is not yet complete.

[0057] In turning assist driving mode, the system switches between turning assist stop mode (Stop Assist Turn) and turning assist drive mode (Active Assist Turn) based on conditions 3 and 4.

[0058] The turning assist stop mode is equivalent to the normal operation mode. The turning assist drive mode includes the Shift Control mode and the Allocation Rudder mode.

[0059] Condition 3 is that either condition (3-1) or (3-2) below is met. (3-1) The indicated steering angle must be less than the steering angle threshold Ath. (3-2) The shift instruction must be in the neutral position N or the reverse position R (Neutral / Reverse). The steering angle threshold Ath may be set to, for example, 10 degrees. However, the steering angle threshold Ath is not limited to the above and may be set to, for example, 5 degrees or 15 degrees. The steering angle threshold Ath can be changed according to the design specifications, as long as stability during straight-line driving is ensured.

[0060] Condition 4 is that both of the following conditions (4-1) and (4-2) are met. (4-1) The indicated steering angle must be greater than or equal to the steering angle threshold Ath. (4-2) The shift instruction is in the forward position F (Forward).

[0061] The Shift Control Mode is a control mode designed to reduce shift shock. The Shift Control Mode includes the Control Assist Turn Mode, Hold Shift Mode, Changing Shift Mode, and Neutral Shift Mode.

[0062] In shift control mode, the turning assist control mode and shift maintenance mode are switched based on conditions 5 and 8. Additionally, the turning assist control mode and shift change mode are switched based on condition 5. Furthermore, the shift maintenance mode and shift neutral position mode are switched based on condition 6. Finally, the shift neutral position mode and shift change mode are switched based on condition 7.

[0063] In turning assist control mode, the following information calculated by turning assist is displayed. Shift position • Lever opening (position of thrust input unit 7) In shift hold mode, the following controls are performed: • Gradually decrease the lever opening indication. • Indicates the actual shift position. In shift neutral position mode, the following instructions (controls) are performed. • Set the shift lever to the neutral position. Set the lever opening to 0%. In shift change mode, the following instructions (controls) are performed. • Set the shift position to the one calculated by the turning assist. Set the lever opening to 0%.

[0064] Condition 5 is that the shift instruction and the actual shift position are equal. Condition 6 is that the actual engine speed is below the threshold for the allowable engine speed for shift changes. The permissible engine speed threshold for shifting under condition 6 may be set to, for example, 1000 [rpm] or 1500 [rpm]. Note that the permissible engine speed threshold for shifting is not limited to the above and can be changed according to the design specifications.

[0065] Condition 7 is that a certain amount of time has elapsed since the actual shift position was in the neutral position N (Neutral). The certain amount of time in Condition 7 may be set to, for example, 0.1 [s]. Note that the certain amount of time in Condition 7 is not limited to the above and can be changed according to the design specifications.

[0066] Condition 8 is that both of the following conditions (8-1) and (8-2) are met. (8-1) Not in the process of shifting gears. (8-2) A certain amount of time has elapsed since the shift instruction and the actual shift position were not equal. The constant time under condition 8 may be set to, for example, 0.1 [s]. Note that the constant time under condition 8 is not limited to the above and can be changed according to the design specifications.

[0067] The rudder assignment mode converts the helm-indicated steering angle to the thrust calculation steering angle (large steering angle). The rudder assignment mode is executed by the control unit as needed.

[0068] Figure 12 is a flowchart illustrating the main flow of the turning assist control according to the embodiment. Figure 13 is an explanatory diagram of a simulated large steering turn according to the embodiment. Note that condition (8-2) of condition 8 is omitted in the flowchart of Figure 12. Referring to Figures 12 and 13, in step S10, the control unit 5 determines whether the indicated steering angle condition is met. The indicated steering angle corresponds to the angle obtained by converting the amount of steering wheel operation into the amount of steering of the thruster 3. As the indicated steering angle condition, the control unit 5 determines whether the indicated steering angle is greater than or equal to the steering angle threshold Ath (for example, 10 degrees or more). For example, if the thruster 3 can be steered by 30 degrees when the steering wheel is turned 2 turns on one side, then in step S10, the result is "YES" if the steering wheel is turned 2 / 3 of a turn (240 degrees) or more. If the indicated steering angle condition is met in step S10 ("YES"), the process proceeds to step S11. If the indicated steering angle condition is not met in step S10 ("NO"), the process proceeds to step S15.

[0069] In step S11, the control unit 5 calculates a simulated large steering angle. The control unit 5 has a map pre-stored in it, as shown in Figure 13. The map shown in Figure 13 shows the relationship between the instructed steering angle and the simulated large steering angle. In turning assist control, the control unit 5 may correct the steering instruction to the thruster 3 so that it is larger than the instructed steering value. This correction (applying a simulated large steering angle) allows for a quicker and larger instructed steering angle compared to the normal instructed steering angle. For example, if a full steering turn is normally achieved when the steering wheel is rotated twice on one side, applying a simulated large steering angle may correct the steering so that a full steering turn is achieved when the steering wheel is rotated once on one side.

[0070] In the example shown in Figure 13, if the indicated steering angle is less than the steering angle threshold Ath, that is, up to the indicated steering angle at which the turning assist is activated (e.g., 10 degrees), no correction for simulated large steering is applied. When simulated large steering is applied, in the region above the indicated steering angle at which the turning assist is activated (e.g., 10 degrees), the simulated large steering angle and the indicated steering angle are different (simulated large steering angle ≠ indicated steering angle), so the simulated large steering angle and the actual steering angle are never equal. Therefore, when simulated large steering is applied, the turning assist is always activated.

[0071] After step S11, proceed to step S12. Note that calculating the simulated large steering angle is not mandatory. For example, if the answer in step S10 is "YES" after step S11, you may proceed to step S12 without executing step S11.

[0072] In step S12, the control unit 5 calculates the turning force corresponding to the steering instruction. The turning force corresponding to the steering instruction is calculated using the above-mentioned relational equation (see Figures 7 to 9). After step S12, the process proceeds to step S13.

[0073] In step S13, the control unit 5 calculates the thrust required to achieve the turning force calculated in step S12 using actual steering. The thrust required to achieve the turning force calculated in step S12 using actual steering is calculated using the above-mentioned relational equation (see Figures 7 to 9). The thrust calculated in step S13 is proportional to, for example, the square of the propeller rotation speed. After step S13, the process proceeds to step S14.

[0074] In step S14, the control unit 5 calculates the throttle valve opening (TH opening) from the thrust calculated in step S13. The control unit 5 transmits the calculated TH angle information to a drive control unit (not shown, e.g., FI-ECU) that controls the drive of each thruster 3. The drive control unit of each thruster 3 determines, for example, the motor drive voltage and the target throttle valve opening.

[0075] In step S15, the control unit 5 calculates the throttle valve opening (TH opening) from the instructed thrust. The control unit 5 transmits the calculated TH angle information to a drive control unit (not shown, e.g., FI-ECU) that controls the drive of each thruster 3.

[0076] Figure 14 is a flowchart showing the flow for suppressing shift shock in the turning assist control according to the embodiment. Referring also to Figure 14, the control to suppress shift shock is performed, for example, in the order of conditions 8, 6, 7, and 5 of the state transitions shown in Figure 10. The example shown in Figure 14 corresponds to an example in which, in turning assist control, when the actual shift, which is the actual shift position of the thruster 3, differs from the corrected shift, which is the shift instruction for the corrected thrust, the control unit 5 matches the actual shift and then executes turning assist control with the corrected thrust.

[0077] In step S20, the control unit 5 determines whether the actual shift is the same as the calculated shift (corrected shift). If the actual shift is the same as the calculated shift in step S20 ("YES"), the process proceeds to step S21. If the actual shift is not the same as the calculated shift in step S20 ("NO"), the process proceeds to step S23.

[0078] In step S21, the control unit 5 performs a shift maintenance. As a shift maintenance, the control unit 5 performs the shift maintenance mode shown in Figure 10. After step S21, the system proceeds to step S22.

[0079] In step S22, the control unit 5 sets the TH opening change permission flag. This allows the opening of the throttle valve to be changed. This permission makes it possible to increase or decrease the thrust of the thruster 3.

[0080] In step S23, the control unit 5 determines whether the actual shift is in the gear-in state. The gear-in state means that the shift position is in the forward position F or the reverse position R. If the actual shift is in the gear-in state in step S23 ("YES"), the process proceeds to step S24. If the actual shift is not in the gear-in state in step S23 ("NO"), the process proceeds to step S27.

[0081] In step S24, the control unit 5 determines whether the rotational speed is less than the allowable rotational speed. In step S24, the control unit 5 determines whether condition 6 (the actual engine rotational speed is below the allowable rotational speed threshold for shift changes) is met. If condition 6 is met in step S24 ("YES"), the process proceeds to step S25. If condition 6 is not met in step S24 ("NO"), the process proceeds to step S26.

[0082] In step S25, the control unit 5 performs a shift change. As a shift change, the control unit 5 changes the shift position from the forward position F or the reverse position R to the neutral position N.

[0083] In step S26, the control unit 5 maintains the shift position (maintaining the shift position in the forward position F or reverse position R) and reduces the actual engine speed to below a predetermined level.

[0084] In step S27, the control unit 5 determines whether the shift N state (the state in which the shift position is in the neutral position N) has continued for a certain period of time. If the shift N state has continued for a certain period of time in step S27 ("YES"), the process proceeds to step S28. If the shift N state has not continued for a certain period of time in step S27 ("NO"), the process proceeds to step S29.

[0085] In step S28, the control unit 5 performs a shift change to the calculated shift position. In step S28, the control unit 5 changes the shift position from the neutral position N to the calculated shift position, which is either the forward position F or the reverse position R.

[0086] In step S29, the control unit 5 performs shift N maintenance (maintaining the shift position in the neutral position N).

[0087] After steps S22, S25, S26, 28, and S29, the process proceeds to a predetermined control process.

[0088] <Example of propulsion system operation> Figure 15 is a timing chart illustrating a first example of the operation of the propulsion system 100 according to the embodiment. Figure 16 is a timing chart illustrating a second example of the operation of the propulsion system 100 according to the embodiment. Figures 15 and 16 illustrate the operation when the ship 1 is turned to the right by full rudder.

[0089] In Figures 15 and 16, the vertical axis, from top to bottom, represents the directed steering angle, the actual steering angle, the thrust (thrust of the left and right propulsion units), and the shift position (shift position of the left and right propulsion units), while the horizontal axis represents time. For directed steering, Rmax represents the maximum value for right steering (maximum directed steering angle when steering to the right), Lmax represents the maximum value for left steering (maximum directed steering angle when steering to the left), Rth represents the steering angle threshold (Ath) for right steering, and Lth represents the steering angle threshold (Ath) for left steering. For actual steering, Rmax represents the maximum value for right steering (maximum actual steering angle when steering to the right), and Lmax represents the maximum value for left steering (maximum actual steering angle when steering to the left). In terms of thrust, the dashed line represents the thrust before correction, the dashed line represents the thrust of the left thruster 3L, and the solid line represents the thrust of the right thruster 3R. Note that the dashed and solid lines correspond to the thrust before correction with or without the thrust difference (ΔF). In terms of shift position, F represents the forward position, N represents the neutral position, and R represents the reverse position. In terms of shift position, the dashed line represents the shift position of the left thruster 3L, and the solid line represents the shift position of the right thruster 3R. Note that in Figures 15 and 16, the thrust instruction (i.e., the opening of the instruction lever = input from the remote control lever by the user) is assumed to remain fixed at a predetermined position. Specifically, as indicated by "Before Correction" next to "Thrust" in Figures 15 and 16, the thrust instruction is set so that the thrust would be "Before Correction" if this turning assist control were not in place (i.e., if the thrusters output the thrust as instructed under normal control).

[0090] As shown in Figure 15, in order to turn ship 1 to the right by full steering, in the guided steering, at time t1, the user begins turning the steering wheel to the right. Then, from time t1 to t4, the guided steering angle gradually increases toward Rmax. In the guided steering, at time t2, the guided steering angle becomes greater than or equal to the steering angle threshold Rth. In the guided steering, time t4 corresponds to the end of the steering wheel turn (the full steering position for a right turn).

[0091] In directed steering, at time t6, the user begins turning the steering wheel in the return direction. Then, from time t6 to t9, the directed steering angle gradually decreases toward zero. In directed steering, at time t8, the directed steering angle becomes less than the steering angle threshold Rth. In directed steering, time t9 corresponds to the end of the steering wheel's return (the position after returning from full right-hand steering to the center).

[0092] In actual steering, there is a delay in responding to the directed steering. In actual steering, at time t3, the thrust direction change device 4 starts turning the rudder of the propeller 3 clockwise. Then, from time t3 to t5, the actual steering gradually increases toward Rmax. In actual steering, time t5 corresponds to the end of the steering of the propeller 3.

[0093] In actual steering, at time t7, the thrust direction change device 4 begins to turn the rudder of the propeller 3 in the return direction. Then, from time t7 to t10, the actual steering gradually decreases toward zero. In actual steering, time t10 corresponds to the end of the return of the propeller 3's rudder.

[0094] In terms of thrust, at time t2, when the indicated steering angle becomes greater than or equal to the steering angle threshold Rth, the thrust of the left thruster 3L begins to increase from before the correction, and the thrust of the right thruster 3R begins to decrease from before the correction. Then, from time t2 to t3, the thrust of the left thruster 3L gradually increases, and the thrust of the right thruster 3R gradually decreases toward zero. After that, from time t3 to t4, the thrust of the left thruster 3L gradually increases, and the thrust of the right thruster 3R gradually increases toward the negative side, more slowly than the thrust change from time t2 to t3. After that, from time t4 to t5, the thrust of the left thruster 3L decreases toward the pre-correction value, and the thrust of the right thruster 3R increases toward the pre-correction value.

[0095] In terms of thrust, from time t5 to t6, the thrust of the left thruster 3L and the thrust of the right thruster 3R remain constant, the same as before correction. Then, from time t6 to t7, the thrust of the right thruster 3R begins to increase from before correction, and the thrust of the left thruster 3L begins to decrease from before correction. Subsequently, more gradually than the thrust change from time t6 to t7, from time t7 to partway through t8, the thrust of the right thruster 3R gradually increases, and the thrust of the left thruster 3L gradually increases toward the negative side. Then, from partway through t8 to time t8, the thrust of the right thruster 3R decreases toward the pre-correction value, and the thrust of the left thruster 3L increases toward the pre-correction value. After that, from time t8 onward, the thrust of the left thruster 3L and the thrust of the right thruster 3R become constant, the same as before correction.

[0096] In the shift position, the left thruster 3L maintains the forward position F until time t7. Then, from time t7 to t8, the left thruster 3L's shift position changes in the following order: neutral position N, reverse position R, neutral position N. After that, from time t8 onward, the left thruster 3L maintains the forward position F.

[0097] In the shift position, the right thruster 3R maintains the forward position F until time t3. Then, from time t3 to t4, the shift position of the right thruster 3R changes in the order of neutral position N, then reverse position R. Then, from time t4 to t5, the shift position of the right thruster 3R changes in the order of reverse position R, neutral position N, then forward position F. After that, from time t5 onward, the shift position of the right thruster 3R maintains the forward position F.

[0098] In this embodiment, the control unit 5 executes turning assist control when the instructed steering angle to the propulsion unit 3, based on the instructed steering value, is greater than or equal to the steering angle threshold Ath. In the example shown in Figure 15, turning assist is activated between time t2 and time t5 when the instructed steering angle is greater than or equal to the steering angle threshold Rth, and between time t6 and time t8 when the instructed steering angle is greater than or equal to the steering angle threshold Rth. In the example shown in Figure 15, turning assist is not activated until time t2 when the instructed steering angle is less than the steering angle threshold Rth, and from time t8 onward.

[0099] In this embodiment, the control unit 5 executes turning assist control when the difference between the instructed steering angle to the thruster 3 based on the instructed steering value and the actual steering angle at which the thruster 3 is actually steering is greater than or equal to the angle difference threshold Dth. For example, the angle difference threshold Dth may be set to 10 degrees. However, the angle difference threshold Dth is not limited to the above and may be set to 5 degrees or 15 degrees. The angle difference threshold Dth can be changed according to the design specifications. In the example shown in Figure 15, the turning assist does not operate between time t5 and time t6, when the instructed steering angle is Rmax and the actual steering angle is Rmax.

[0100] In this embodiment, among the multiple propulsion units 3, the propulsion unit 3 located on the inside relative to the turning direction of the hull 2 ​​is designated as the inner propulsion unit, and the propulsion unit 3 located on the outside relative to the turning direction of the hull 2 ​​is designated as the outer propulsion unit. In this case, the control unit 5 reduces the thrust of the inner propulsion unit to below a predetermined thrust and increases the thrust of the outer propulsion unit to above a predetermined thrust in turning assist control. In the example shown in Figure 15, when the ship 1 is turned to the right, the left propulsion unit 3L becomes the outer propulsion unit, and the right propulsion unit 3R becomes the inner propulsion unit. In the example shown in Figure 15, during the time t2 to t4 while turning assist is in operation, the thrust of the right propulsion unit 3R (inner propulsion unit) is reduced to below the pre-correction level, and the thrust of the left propulsion unit 3L (outer propulsion unit) is increased to above the pre-correction level.

[0101] Figure 16 illustrates the operation when the steering instruction to the propulsion engine 3 is corrected to be larger than the instruction value when turning the vessel 1 to the right by full steering. In Figure 16, the thick dashed line in the upper part of the vertical axis indicates the simulated large steering (simulated large steering angle). In the explanation of Figure 16, detailed explanations of the same content as in Figure 15 are omitted.

[0102] As shown in Figure 16, in order to make the ship 1 turn to the right by full steering, in the guided steering, at time t1, the user begins to turn the steering wheel clockwise. In the guided steering, at time t2, the guided steering angle becomes greater than or equal to the steering angle threshold Rth. In the guided steering, a simulated large steering turn is applied at time t2. When the simulated large steering turn is applied, the simulated large steering angle gradually increases from time t2 to t4, at a steeper rate than the angle change of the guided steering. In the simulated large steering turn, the simulated large steering angle remains constant from time t4, when the guided steering is at its full steering position, to time t6.

[0103] In directed steering, at time t6, the user begins turning the steering wheel in the direction of returning it to the center. In directed steering, at time t8, the directed steering angle becomes less than the steering angle threshold Rth. In directed steering, at time t8, the simulated large steering input ceases to function.

[0104] In terms of thrust, at time t2, when the indicated steering angle becomes greater than or equal to the steering angle threshold Rth, the thrust of the left thruster 3L begins to increase from before the correction, and the thrust of the right thruster 3R begins to decrease from before the correction. Due to the effect of the simulated large steering turn, the thrust of the left thruster 3L increases more rapidly from time t2 to partway through t3, and the thrust of the right thruster 3R decreases toward zero, more rapidly than the thrust change shown in Figure 15. After that, more gradually than the thrust change from time t2 to partway through t3, the thrust of the left thruster 3L gradually increases from partway through time t3 to time t4, and the thrust of the right thruster 3R gradually increases toward the negative side. After that, from time t4 to t5, the thrust of the left thruster 3L gradually decreases toward the positive side before the correction, and the thrust of the right thruster 3R gradually increases toward the point between zero and the pre-correction value.

[0105] In terms of thrust, from time t5 to t6, the thrust of the left thruster 3L and the thrust of the right thruster 3R remain constant, the same as the thrust at time t5. Then, from time t6 to partway through t8, the thrust of the right thruster 3R gradually increases, and the thrust of the left thruster 3L gradually decreases. Then, from time t7 to partway through t8 and up to time t8, the thrust of the right thruster 3R decreases towards the pre-correction value, and the thrust of the left thruster 3L increases towards the pre-correction value. After that, from time t8 onward, the thrust of the left thruster 3L and the thrust of the right thruster 3R become constant, the same as the pre-correction value.

[0106] In terms of shift position, the left thruster 3L always maintains the forward position F. In the shift position, the right thruster 3R maintains the forward position F until time t3. Then, from time t3 to t4, the shift position of the right thruster 3R changes in the order of neutral position N, then reverse position R. Then, from time t4 to t5, the shift position of the right thruster 3R changes in the order of reverse position R, neutral position N, then forward position F. After that, from time t5 onward, the shift position of the right thruster 3R maintains the forward position F.

[0107] In the example shown in Figure 16, a simulated large turn is activated at time t2 when the indicated steering angle becomes greater than or equal to the steering angle threshold Rth. Even after the full steering of the propulsion engine 3 is complete, the actual steering cannot keep up with the simulated large turn, so the turning assist operates as long as the indicated steering angle is greater than or equal to the steering angle threshold Rth. In the example shown in Figure 16, the turning assist operates from time t2 to time t8 when the indicated steering angle is greater than or equal to the steering angle threshold Rth. The turning assist does not operate until time t2 when the indicated steering angle is less than the steering angle threshold Ath, and from time t8 onward.

[0108] In this embodiment, the control unit 5 calculates the steering thrust in turning assist control based on the upper or lower thrust limit when the thruster 3 actually turns. For example, let's assume the upper limit of thrust for thruster 3 is 100. Hereafter, for the left and right thrusters 3, we will use (thrust, turning force of thrust) as an example. The thrust generated by the steering instruction is set as follows: left thruster 3L (80, 40) and right thruster 3R (80, 20). The ideal thrust achieved during actual steering is 3L (110, 55) for the left thruster and 3R (50, 5) for the right thruster. In this case, the thrust under actual steering cannot exceed 100. Under actual steering, the theoretical upper limit of thrust is reached when the throttle valve opening is at its maximum and the engine speed is at its maximum. Therefore, based on the upper limit of thrust when the propulsion unit 3 actually turns, the left propulsion unit 3L is designated as (100, 50) and the right propulsion unit 3R as (50, 5).

[0109] In the example above, the ideal ΔF shown in Figure 8 is prioritized, resulting in ΔF = turning force of 15. On the other hand, it is also possible to keep the sum of the numbers on the left side of the total thrust (XX, XX) unchanged. For example, based on the upper limit of thrust when thruster 3 actually turns, the left thruster 3L could be set to (100, 50) and the right thruster 3R to (60, 10). In this case, the total thrust of 160 is maintained, but instead ΔF becomes 10.

[0110] In this embodiment, the control unit 5 acquires the instructed steering value input to the steering angle input unit 6, the actual steering value of the propulsion unit 3, and the instructed thrust value input to the thrust input unit 7 during turning assist control. It then calculates the steering thrust generated by the instructed thrust value when the direction of the propulsion unit 3's rudder reaches the instructed steering value, and calculates a correction thrust that generates the calculated steering thrust at the actual steering value.

[0111] Figure 17 shows an example of a map for realizing the turning assist control according to the embodiment. In the map of Figure 17, each axis is assigned as follows. C_SHIFT_MAP: Shift position (1=forward position F / 2=neutral position N / 3=reverse position R) Breakpoints F or Dimension 1: Lever opening (0-100%) C_to THRUST_MAP: Propeller thrust (squared of rotational speed) Referring to Figure 17, in order to realize turning assist control, the control unit 5 may have pre-stored maps showing, for example, the relationship between the lever opening and the throttle valve opening, the relationship between the throttle valve opening and the engine speed, and the relationship between the engine speed and thrust. In this case, the control unit 5 converts the instruction lever opening (user input to the remote control lever) to the throttle valve opening, calculates the engine speed based on the converted throttle valve opening, and calculates the current thrust based on the calculated engine speed. Then, the control unit 5 calculates the thrust due to turning assist based on the calculated current thrust, converts the calculated thrust to the engine speed, and converts the converted engine speed to the throttle valve opening (after correction). The control unit 5 can perform mutual conversion between the lever opening and the throttle valve opening, mutual conversion between the throttle valve opening and the engine speed, and mutual conversion between the engine speed and thrust using the above maps.

[0112] In the timing charts described above, the example is always for steering to the right, but it is possible to perform steering to the left using the same threshold as for steering to the right. Also, in this embodiment, the example is for turning control performed on the F side (forward), but turning control may also be performed on the R side (reverse). In turning control on the R side, the threshold for steering instruction and the thrust calculation method are the same as in turning control on the F side.

[0113] <Effects and Effects> As described above, the propulsion system 100 of the ship 1 in the above embodiment includes a power source 12, a propulsion unit 14 that generates thrust by power transmitted from the power source 12, a plurality of propulsion machines 3 provided on the left and right sides of the center of the hull 2, a thrust direction changing device 4 that changes the direction of the thrust of the plurality of propulsion machines 3, and a control unit 5 that controls the thrust and thrust direction of the plurality of propulsion machines 3. When there is a difference between the instructed steering angle and the actual steering angle during a turn of the ship 1, the control unit 5 performs turning assist control that generates a thrust balance corresponding to the difference. In turning assist control, the control unit 5 acquires the instructed steering angle value input to the steering angle input unit 6, the actual steering angle value when the propulsion machines 3 are actually turning, and the instructed thrust value input to the thrust input unit 7, calculates the steering thrust generated by the instructed thrust value when the direction of the rudder of the propulsion machines 3 reaches the instructed steering angle value, and calculates a correction thrust that generates the calculated steering thrust at the actual steering angle value. With this configuration, when the vessel 1 turns, the delay between the actual steering of the propulsion engine 3 and the instructed steering direction is taken into account, and the steering thrust of the propulsion engine 3 after reaching the instructed steering direction is realized with the current actual steering direction which is delayed. As a result, the turning force desired by the user can be quickly achieved. Therefore, responsiveness during turns is improved, and navigation can be carried out in accordance with the operator's intentions.

[0114] In the above embodiment, the control unit 5 executes turning assist control when the instructed steering angle to the thruster 3 based on the instructed steering value is greater than or equal to the steering angle threshold Ath. This configuration makes it possible to suppress the execution of turning assist control when the vessel 1 is moving in a straight line.

[0115] In the above embodiment, the control unit 5 executes turning assist control when the difference between the instructed steering angle to the thruster 3 based on the instructed steering value and the actual steering angle at which the thruster 3 is actually steering is greater than or equal to the angle difference threshold Dth. This configuration makes it possible to suppress instability in operation (hunting) caused by turning assist control.

[0116] In the above embodiment, among the multiple propulsion units 3, the propulsion unit 3 located on the inside relative to the turning direction of the hull 2 ​​is designated as the inner propulsion unit, and the propulsion unit 3 located on the outside relative to the turning direction of the hull 2 ​​is designated as the outer propulsion unit. In this case, the control unit 5 reduces the thrust of the inner propulsion unit to below a predetermined thrust and increases the thrust of the outer propulsion unit to above a predetermined thrust in turning assist control. This configuration allows for improved responsiveness during turns compared to a case where the thrust of the inner thruster is increased to above a predetermined thrust and the thrust of the outer thruster is reduced to below a predetermined thrust in the turning assist control.

[0117] In the above embodiment, the control unit 5 corrects the steering instruction to the thruster 3 in the turning assist control so that it becomes larger than the instruction steering value. This configuration allows for quicker and larger steering inputs compared to normal steering inputs, thereby improving responsiveness during turns.

[0118] In the above embodiment, when the actual shift position of the thruster 3 and the corrected shift, which is the shift instruction for the corrected thrust, differ, the control unit 5 matches the actual shift position and the corrected shift, and then performs the turning assist control using the corrected thrust. With this configuration, compared to the case where turning assist control is performed by corrected thrust when the corrected shift differs from the actual shift, shocks caused by shift changes (shift shock) can be suppressed.

[0119] In the above embodiment, the control unit 5 calculates the steering thrust in turning assist control based on the angle between a reference line that is parallel to the centerline CL of the stern in a plan view and passes through the steering axis 16 of the propulsion engine 3, and a straight line connecting the center of rotation of the ship 1 and the steering axis 16. This configuration improves responsiveness during turns compared to calculating steering thrust based on the angle between the straight line connecting a point other than the center of rotation point and the steering axis 16 in a plan view, and the aforementioned reference line.

[0120] In the above embodiment, the control unit 5 calculates the steering thrust based on the upper or lower thrust limit when the thruster 3 actually turns, in the turning assist control. With this configuration, the turning assist control does not require the calculation of thrust that exceeds the upper limit or falls below the lower limit of thrust when the thruster 3 actually turns, thus simplifying the control.

[0121] <Variation> In the above embodiment, the control unit was described as executing turn assist control when the instructed steering angle to the thruster based on the instructed steering value is greater than or equal to the steering angle threshold, but it is not limited to this. For example, the control unit may execute turn assist control when the instructed steering angle to the thruster based on the instructed steering value is less than the steering angle threshold. The manner in which turn assist control is executed based on the steering angle threshold can be changed according to the design specifications.

[0122] In the above embodiment, the control unit was described as executing turning assist control when the difference between the instructed steering angle to the propeller based on the instructed steering value and the actual steering angle that the propeller is actually turning is greater than or equal to an angle difference threshold, but it is not limited to this. For example, the control unit may execute turning assist control when the difference between the instructed steering angle to the propeller based on the instructed steering value and the actual steering angle that the propeller is actually turning is less than an angle difference threshold. The manner in which turning assist control is executed based on the angle difference threshold can be changed according to the design specifications.

[0123] In the above embodiment, when the thrusters located on the inside relative to the turning direction of the hull are designated as inner thrusters and the thrusters located on the outside relative to the turning direction of the hull are designated as outer thrusters, the control unit has been shown to reduce the thrust of the inner thrusters to below a predetermined thrust and increase the thrust of the outer thrusters to above a predetermined thrust in turning assist control, but it is not limited to this example. For example, the control unit may increase the thrust of the inner thrusters to above a predetermined thrust and reduce the thrust of the outer thrusters to below a predetermined thrust in turning assist control. The manner in which the thrust of the inner thrusters and / or outer thrusters are increased and decreased in turning assist control can be changed according to the design specifications.

[0124] In the above embodiment, the control unit was described as correcting the steering instruction to the thruster in turn assist control so that it is greater than the instruction steering value, but it is not limited to this. For example, the control unit does not have to correct the steering instruction to the thruster in turn assist control so that it is greater than the instruction steering value. For example, the control unit does not have to perform simulated large steering in turn assist control. The manner in which the instruction steering is corrected in turn assist control can be changed according to the design specifications.

[0125] In the above embodiment, the control unit was described as executing the turning assist control using the corrected thrust after matching the actual shift position (actual shift) with the corrected shift (corrected thrust shift instruction) when the actual shift position of the thruster and the corrected shift differ in turning assist control. However, the control unit is not limited to this example. For example, the control unit may execute the turning assist control using the corrected thrust even when the corrected shift differs from the actual shift. The manner in which the turning assist control is executed using the corrected thrust can be changed according to the design specifications.

[0126] In the above embodiment, the control unit was described as calculating the steering thrust in turning assist control based on the angle between a reference line parallel to the centerline of the stern in a plan view and passing through the steering axis of the propulsion engine, and a straight line connecting the center of rotation of the ship and the steering axis. However, the control unit is not limited to this. For example, in turning assist control, the control unit may calculate the steering thrust based on the angle between a straight line connecting a point other than the center of rotation to the steering axis in a plan view and the above-mentioned reference line. The manner in which the steering thrust is calculated in turning assist control can be changed according to the design specifications.

[0127] In the above embodiment, the control unit was described as calculating the steering thrust based on the upper or lower thrust limit when the thruster actually turns during turning assist control, but it is not limited to this. For example, the control unit may perform control in turning assist control to calculate a thrust that exceeds the upper thrust limit or falls below the lower thrust limit when the thruster actually turns during turning assist control. The control mode for calculating thrust in turning assist control can be changed according to the design specifications.

[0128] Furthermore, it may be applied to various types of watercraft, such as V-shaped hulls, pontoon boats, center consoles, runabouts, fishing boats, and jet skis.

[0129] In the above embodiment, an example was given in which the power source is an internal combustion engine, but it is not limited to this. For example, the power source may be an electric motor or the like. In the case of an electric motor, the motor speed and torque correspond to "thrust". In this case, setting the motor speed to zero results in the neutral position N. When performing autonomous driving or driver assistance (for example, autopilot or cruise control for constant speed driving), instead of the user (operator) inputting the thrust of the propulsion system (required thrust), the system may be configured so that the computer calculates the instruction value and sets the target speed, etc.

[0130] Furthermore, all or part of the processing performed by the promotion system may be carried out by recording a program to realize all or part of the functions of the promotion system in this disclosure on a computer-readable recording medium, loading the program recorded on this recording medium into a computer system, and executing it. Here, "computer system" includes hardware such as the OS and peripheral devices. "Computer system" also includes a WWW system equipped with a homepage provisioning environment (or display environment). "Computer-readable recording medium" refers to portable media such as flexible disks, magneto-optical disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into a computer system. Furthermore, "computer-readable recording medium" also includes volatile memory (RAM) within a computer system that acts as a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, which retains the program for a certain period of time.

[0131] Furthermore, the above program may be transmitted from a computer system that stores the program in a memory device or the like to another computer system via a transmission medium or by transmission waves within the transmission medium. Here, the "transmission medium" for transmitting the program refers to a medium that has the function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. Furthermore, the above program may be for the purpose of realizing a part of the functions described above. Moreover, it may be a so-called differential file (differential program) that can realize the functions described above in combination with a program already recorded in the computer system.

[0132] Although embodiments for carrying out the present invention have been described above using examples, the present invention is not limited in any way to these embodiments, and various modifications and substitutions can be made without departing from the spirit of the present invention. [Explanation of Symbols]

[0133] 1 ship 2 hull 3 Propulsion machine 3L left propulsion machine 3R right propulsion machine 4. Thrust direction change device 5. Control Unit 6. Steering Angle Input Section 7. Thrust input section 12 Power source 14 Promotion Department 16. Steering axis 100 Propulsion System Ath steering angle threshold CL center line

Claims

1. It has a power source and a propulsion unit that generates thrust by power transmitted from the power source, and a plurality of propulsion machines are provided on the left and right sides of the ship's center, A thrust direction changing device for changing the direction of thrust from multiple propulsion machines, A ship propulsion system comprising a control unit that controls the thrust and direction of thrust of a plurality of propulsion units, The control unit, when there is a difference between the instructed steering and the actual steering during the turning of the vessel, performs turning assist control to generate a thrust balance corresponding to the difference. The control unit, in the turning assist control, acquires an instructed steering value input to the steering angle input unit, an actual steering value when the propulsion unit is actually steering, and an instructed thrust value input to the thrust input unit, calculates the steering thrust generated by the instructed thrust value when the direction of the propulsion unit's rudder reaches the instructed steering value, and calculates a correction thrust that generates the calculated steering thrust at the actual steering value. A ship's propulsion system.

2. The control unit executes the turning assist control when the instructed steering angle to the propulsion system based on the instructed steering value is greater than or equal to the steering angle threshold. The propulsion system for a ship according to claim 1.

3. The control unit executes the turning assist control when the difference between the instructed steering angle to the propulsion system based on the instructed steering value and the actual steering angle at which the propulsion system is actually steering is greater than or equal to an angle difference threshold. A ship propulsion system according to claim 1 or 2.

4. If, among the multiple propulsion systems, the propulsion system located on the inside relative to the hull's turning direction is designated as the inside propulsion system, and the propulsion system located on the outside relative to the hull's turning direction is designated as the outside propulsion system, The control unit, in the turning assist control, reduces the thrust of the inner thruster to below a predetermined thrust and increases the thrust of the outer thruster to above a predetermined thrust. A ship propulsion system according to claim 1 or 2.

5. The control unit corrects the steering instruction to the thruster in the turning assist control so that it becomes larger than the instruction steering value. The propulsion system for a ship according to claim 1.

6. In the turning assist control, if the actual shift position of the thruster and the corrective shift, which is a shift instruction for corrective thrust, are different, the control unit will match the actual shift position and the corrective shift, and then execute the turning assist control using the corrective thrust. A ship propulsion system according to claim 1 or 2.

7. The control unit calculates the steering thrust in the turning assist control based on the angle formed by a reference line that is parallel to the centerline of the stern in a plan view and passes through the steering axis of the propulsion engine, and a straight line connecting the center of rotation of the vessel and the steering axis. A ship propulsion system according to claim 1 or 2.

8. The control unit calculates the steering thrust based on the upper or lower thrust limit when the propulsion system actually turns, in the turning assist control. A ship propulsion system according to claim 1 or 2.

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