SYSTEM FOR CONTROLLING WATERCRAFT, METHOD OF CONTROLLING WATERCRAFT, AND WATERCRAFT

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2024-201139 filed on Nov. 18, 2024. The entire contents of this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to systems for controlling watercraft, methods of controlling watercraft, and watercraft.

2. Description of the Related Art

As a control executed in an automated watercraft operation, there has been known a compass direction keeping control for keeping a watercraft oriented to a target compass direction (Japan Laid-open Patent Application Publication No. 2023-068838). The compass direction keeping control serves as a type of control executed in the automated watercraft operation to move the watercraft under the influence of external forces, with the watercraft being kept oriented to the target compass direction by causing the watercraft to perform bow turning.

Under the compass direction keeping control, when a thrust is generated for causing the watercraft to perform bow turning, not only a thrust component oriented in the right-and-left direction but also that oriented in the back-and-forth direction are outputted to the watercraft. Because of this, in such an exemplary situation that the watercraft is applied with an external force oriented in one direction, when the compass direction keeping control is executed, with the rudder angle of a marine propulsion device being turned in one direction, the thrust component outputted in the back-and-force direction is undesirably oriented to only either the front side or the rear side in an eccentric manner such that the watercraft may be gradually displaced in position in the back-and-forth direction.

SUMMARY OF THE INVENTION

Example embodiments of the present invention enhance a position keeping accuracy in a compass direction keeping control.

A system according to an example embodiment of the present invention relates to a system for controlling a watercraft and includes a marine propulsion device and a controller. The marine propulsion device includes a propeller to generate a thrust to propel the watercraft. The controller is configured or programmed to execute a compass direction keeping control to keep the watercraft oriented in a target compass direction by controlling both a magnitude and a direction of the thrust. The controller is configured or programmed to turn the propeller between a first steering position and a second steering position at a predetermined time interval in the compass direction keeping control. The first steering position is a position where the thrust is applied to the watercraft in a back-and-forth direction and a right-and-left direction. The second steering position is a position obtained by reversing the first steering position in either the back-and-forth direction or the right-and-left direction. The controller is configured or programmed to control the magnitude of the thrust and a rotational direction of the propeller such that the watercraft performs bow turning toward the target compass direction when the propeller is located in each of the first and second steering positions. The controller is configured or programmed to control the rotational direction of the propeller such that a direction of the thrust in the back-and-forth direction generated at the first steering position and a direction of the thrust in the back-and-forth direction generated at the second steering position are opposite when the watercraft is caused to perform bow turning in a same direction at the first steering position and the second steering position.

A method according to another example embodiment of the present invention relates to a method of controlling a watercraft and includes executing a compass direction keeping control to keep the watercraft oriented in a target compass direction by controlling both a magnitude and a direction of a thrust generated by a marine propulsion device, turning a propeller of the marine propulsion device between a first steering position and a second steering position at a predetermined time interval in the compass direction keeping control, controlling the magnitude of the thrust and a rotational direction of the propeller such that the watercraft performs bow turning toward the target compass direction when the propeller is located in each of the first and second steering positions, and controlling the rotational direction of the propeller such that a direction of the thrust in a back-and-forth direction generated at the first steering position and a direction of the thrust in the back-and-forth direction generated at the second steering position are opposite when the watercraft is caused to perform bow turning in a same direction at the first steering position and the second steering position. The first steering position is a position where the thrust is applied to the watercraft in the back-and-forth direction and a right-and-left direction. The second steering position is a position obtained by reversing the first steering position in either the back-and-forth direction or the right-and-left direction.

In the systems and the methods according to example embodiments of the present invention, in the compass direction keeping control, when the watercraft is caused to perform bow turning in an identical direction regardless of whether the propeller is located in the first steering position or the second steering position, the rotational direction of the propeller is controlled such that the thrust generated in the back-and-forth direction when the propeller is located in the first steering position and that generated in the back-and-forth direction when the propeller is located in the second steering position are oriented opposite to each other. In other words, by reversing the first steering position of the propeller at the predetermined time interval, a back-and-forth directional thrust component, oriented in a direction opposite to that generated when the propeller is located in the first steering position, is able to be generated when the propeller is located in the second steering position. Accordingly, the back-and-forth directional thrust component, generated by the thrust to cause the watercraft to perform bow turning, can be prevented from being oriented to only either the front side or the rear side in an eccentric manner. As a result, it is possible to enhance the position keeping accuracy in the compass direction keeping control.

According tom example embodiments of the present invention, it is possible to enhance the position keeping accuracy in the compass direction keeping control.

The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a watercraft including a marine propulsion device according to an example embodiment of the present invention.

FIG. 2 is a side view of the marine propulsion device.

FIG. 3 is a diagram for explaining an electric motor.

FIG. 4 is a schematic diagram showing a configuration of a watercraft operating system.

FIG. 5 is a front view of a joystick.

FIG. 6 is a diagram showing a series of motions of the watercraft in a compass direction keeping control.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

Example embodiments of the present invention will be hereinafter explained with reference to drawings. FIG. 1 is a perspective view of a watercraft 10 including a watercraft operating system 100 according to an example embodiment of the present invention. The watercraft 10 includes a hull 2 and a marine propulsion device 3. More specifically, the watercraft 10 includes a single marine propulsion device 3. In the present example embodiment, the marine propulsion device 3 is an electric outboard motor. The marine propulsion device 3 is attached to the stern of the hull 2 of the watercraft 10. The marine propulsion device 3 is disposed on the stern in the middle of the watercraft 10 in the right-and-left direction. The marine propulsion device 3 generates a thrust to propel the watercraft 10.

FIG. 2 is a side view of the marine propulsion device 3. The marine propulsion device 3 is attached to the hull 2 through a bracket 11. The marine propulsion device 3 is supported by the bracket 11.

The marine propulsion device 3 includes an upper portion 12, a lower portion 13, a propeller 14, a steering device 15, and an electric motor 16 (see FIG. 3). The upper portion 12 is attached to the bracket 11. The lower portion 13 is disposed below the bracket 11. The lower portion 13 is pivotable about the axis of a steering axle 15a (to be described below) with respect to the upper portion 12. The lower portion 13 includes a case portion 13a and a duct 13b. The case portion 13a is integral with the duct 13b. The duct 13b is disposed below the case portion 13a. The duct 13b has a tubular shape. The propeller 14 is disposed on the duct 13b of the lower portion 13. The propeller 14 generates the thrust when rotated by the driving force of the electric motor 16.

The steering device 15 is configured to pivot the lower portion 13. By pivoting the lower portion 13, the steering device 15 changes the orientation of the thrust generated by the rotation of the propeller 14. The steering device 15 includes the steering axle 15a. The steering axle 15a extends in the up-and-down direction. The steering axle 15a is connected to the upper portion 12 and the duct 13b of the lower portion 13. The steering device 15 includes a motor (not shown in the drawings) to rotate the steering axle 15a about the axis thereof. It should be noted that in the present example embodiment, the lower portion 13 of the marine propulsion device 3 is pivotable in the right-and-left direction within an angular range of about 140 degrees (70 degrees on the right side and 70 degrees on the left side), for example. Because of this, the steering device 15 is configured to pivot the lower portion 13 within the angular range of at least 140 degrees, for example.

The electric motor 16 is driven when supplied with electric power from a battery (not shown in the drawings) disposed in the hull 2. The electric motor 16 includes a stator portion 16a and a rotor portion 16b. The stator portion 16a is fixed to the duct 13b. The stator portion 16a includes a coil (not shown in the drawings). The rotor portion 16b is fixed to the propeller 14. The stator portion 16a is disposed opposite to the rotor portion 16b. The rotor portion 16b includes a plurality of magnets (not shown in the drawings). When the coil of the stator portion 16a is provided with electric power, the propeller 14 is rotated together with the rotor portion 16b.

FIG. 4 is a schematic diagram showing a configuration of the watercraft operating system 100. The marine propulsion device 3 includes a motor controller 17 and a steering controller 18. The motor controller 17 and the steering controller 18 may include control circuits, each of which includes a processor such as a CPU (Central Processing Unit) and memories such as a RAM (Random Access Memory) and a ROM (Read-Only Memory). The motor controller 17 stores programs and data to control the electric motor 16. The motor controller 17 is configured or programmed to control the rotational direction and the output of the electric motor 16 in accordance with a command signal outputted thereto from a watercraft operating controller 30 (to be described below).

The steering controller 18 is configured or programmed to control the driving of the steering device 15 in accordance with a command signal outputted thereto from the watercraft operating controller 30. The steering controller 18 stores programs and data to control the steering device 15.

The watercraft operating system 100 includes a steering wheel 24, a remote controller 25, and a joystick 26. The steering wheel 24, the remote controller 25, and the joystick 26 are disposed in a cockpit 10b of the watercraft 10. The cockpit 10b is disposed farther forward than the center of gravity (G) of the watercraft 10 in the back-and-forth direction. The steering wheel 24, the remote controller 25, and the joystick 26 are manually operable.

The steering wheel 24 enables a watercraft operator to manipulate the turning direction of the watercraft 10. The steering wheel 24 includes a sensor 24a. The sensor 24a outputs a steering signal indicating the operating direction and the operating amount of the steering wheel 24.

The remote controller 25 includes a throttle lever 25a. The throttle lever 25a enables the watercraft operator to regulate the magnitude of the thrust generated from the marine propulsion device 3. The throttle lever 25a also enables the watercraft operator to switch the direction of the thrust generated from the marine propulsion device 3 between a forward moving direction and a rearward moving direction. The throttle lever 25a is operable from a neutral position to a forward moving position and a rearward moving position. The neutral position is an intermediate position between the forward moving position and the rearward moving position. The throttle lever 25a includes a sensor 25b. The sensor 25b outputs a throttle signal indicating the operating direction and the operating amount of the throttle lever 25a.

The joystick 26 is tiltable from the neutral position in the back-and-forth direction and the right-and-left direction (sideways direction). In other words, the joystick 26 is tiltable in all compass directions. The joystick 26 is rotatable about a rotational axis Ax1. In other words, the joystick 26 is operable to twist clockwise and counterclockwise about the rotational axis Ax1. The joystick 26 includes a sensor 26a. The sensor 26a outputs an operating signal indicating an operation of the joystick 26. The operating signal contains information regarding the tilt direction and the tilt amount of the joystick 26. The operating signal also contains information regarding the twist direction and the twist amount of the joystick 26. The rudder angle, the magnitude of the output, and the direction of the output of the marine propulsion device 3 are controlled in accordance with the tilt amount and the tilt direction of the joystick 26.

FIG. 5 is a front view of the joystick 26. The joystick 26 includes a joystick button 26b and a compass direction keeping button 31b. The joystick button 26b switches between the following modes: a joystick mode to operate the watercraft 10 with the joystick 26 and a normal mode to operate the watercraft 10 with the remote controller 25 and the steering wheel 24. The compass direction keeping button 31b is configured to receive an operation to start the compass direction keeping control and an operation to end the compass direction keeping control.

The watercraft operating system 100 includes the watercraft operating controller 30. The watercraft operating controller 30 includes a processor such as a CPU and memories such as a RAM and a ROM. The watercraft operating controller 30 stores programs and data to control the marine propulsion device 3. The watercraft operating controller 30 is connected to the motor controller 17 and the steering controller 18 through wired or wireless communication. The watercraft operating controller 30 is connected to the steering wheel 24, the remote controller 25, and the joystick 26 through wired or wireless communication.

The watercraft operating controller 30 outputs command signals to the motor controller 17 and the steering controller 18 based on signals outputted thereto from the sensors 24a and 25b. The watercraft operating controller 30 is configured or programmed to control the rudder angle, the magnitude of the output, and the direction of the output of the marine propulsion device 3 through the motor controller 17 and the steering controller 18. The watercraft operating controller 30 is configured or programmed to control the direction of the output of the marine propulsion device 3 by controlling the rotational direction of the propeller 14.

The watercraft operating controller 30 controls the rudder angle, the magnitude of the output, and the direction of the output of the marine propulsion device 3 in accordance with the tilt direction and the tilt amount of the joystick 26.

The watercraft operating controller 30 is configured or programmed to change the rudder angle of the marine propulsion device 3 such that the watercraft 10 performs bow turning in a direction corresponding to the twist direction of the joystick 26. The watercraft operating controller 30 is configured or programmed to cause the marine propulsion device 3 to generate a thrust in accordance with the twist amount of the joystick 26.

The watercraft operating controller 30 is configured or programmed to change the rudder angle of the marine propulsion device 3 such that the watercraft 10 turns in accordance with an operation of the joystick 26 to not only tilt forward or rearward but also twist. At this time, the watercraft operating controller 30 is configured or programmed to cause the marine propulsion device 3 to generate a thrust in accordance with the tilt amount of the joystick 26 and change the rudder angle of the marine propulsion device 3 such that the watercraft 10 turns in a direction corresponding to the twist direction of the joystick 26.

The watercraft operating system 100 includes a position sensor 31 and a compass sensor 32. The position sensor 31 may include, for instance, a receiver for a GNSS (Global Navigation Satellite System) such as a GPS (Global Positioning System). The position sensor 31 outputs a signal indicating the present position of the watercraft 10. The position sensor 31 is connected to the watercraft operating controller 30 in a communicable manner. The watercraft operating controller 30 is configured or programmed to obtain the position of the watercraft 10 based on the signal outputted thereto from the position sensor 31.

The compass sensor 32 detects the present compass direction of the watercraft 10. The compass sensor 32 may be, for instance, an IMU (Inertial Measurement Unit). The compass sensor 32 is connected to the watercraft operating controller 30 in a communicable manner.

Upon receiving an operating signal outputted in accordance with an operation of the compass direction keeping button 31b, for instance, the watercraft operating controller 30 is configured or programmed to execute the compass direction keeping control to control the marine propulsion device 3 such that the watercraft 10 is kept oriented in a target compass direction. The compass direction keeping control is a type of control executed in an automated watercraft operation to move the watercraft 10 under the influence of external forces, including streams of wind and water, with the watercraft 10 being kept oriented to the target compass direction by causing the watercraft 10 to perform bow turning. When the compass direction of the watercraft 10 is displaced from the target compass direction by a predetermined angle or greater during the compass direction keeping control, the watercraft operating controller 30 is configured or programmed to cause the watercraft 10 to perform bow turning so as to modify the compass direction of the watercraft 10. For example, the target compass direction is a compass direction in which the watercraft 10 was oriented at a point in time when the watercraft operating controller 30 received the operating signal from the compass direction keeping button 31b. Alternatively, for instance, the target compass direction may be an arbitrary compass direction to be specified by an operation inputted by the operator.

FIG. 6 is a diagram schematically showing a series of motions of the watercraft 10 during the compass direction keeping control. The watercraft operating controller 30 turns the propeller 14 between a first steering position and a second steering position at a predetermined time interval in the compass direction keeping control. In other words, the propeller 14 of the marine propulsion device 3 is controlled to continue to turn between the first steering position and the second steering position at a constant time interval during the compass direction keeping control.

The first and second steering positions are positions in which the thrust is applied to the watercraft 10 in the back-and-forth direction and the right-and-left direction. The second steering position is a position set by reversing the first steering position in either the back-and-forth direction or the right-and-left direction. In the present example embodiment, the second steering position is set by reversing the first steering position in the right-and-left direction. For example, the first steering position is a position turned rightward by 70 degrees (+70 degrees), for example, with respect to the back-and-forth direction, and the second steering position is a position turned leftward by 70 degrees (−70 degrees), for example, with respect to the back-and-forth direction. In the present example embodiment, the first and second steering positions correspond to the maximum rudder angles to which the lower portion 13 of the marine propulsion device 3 is pivotable.

The rudder angle corresponding to the first steering position is preferably greater than or equal to 60 degrees and less than or equal to 80 degrees, for example. By thus setting the rudder angle corresponding to the first steering position to be greater than or equal to 60 degrees and less than or equal to 80 degrees, for example, when the watercraft 10 is caused to perform bow turning during the compass direction keeping control, the operator of the watercraft 10 feels as if the watercraft 10 performs bow turning about the cockpit 10b.

The predetermined time interval may be greater than or equal to 20 seconds and less than or equal to 70 seconds, for example. In the present example embodiment, the predetermined time interval is 30 seconds. In other words, the watercraft operating controller 30 continues to execute, for instance, the following steering control from start to end in the compass direction keeping control: in the compass direction keeping control, when 30 seconds elapses after the propeller 14 is turned to the first steering position, the propeller 14 is turned from the first steering position to the second steering position; then, when 30 seconds elapses after the propeller 14 is turned to the second steering position, the propeller 14 is turned from the second steering position to the first steering position.

In the compass direction keeping control, the watercraft operating controller 30 may change the value for the predetermined time interval in accordance with the velocity of the watercraft 10 moving in the right-and-left direction. For example, when the watercraft 10 moves fast in the right-and-left direction, the watercraft operating controller 30 may increase the value of the predetermined time interval. The velocity of the watercraft 10 moving in the right-and-left direction may be calculated by, for instance, the position sensor 31 or a velocity sensor.

In the compass direction keeping control, the watercraft operating controller 30 is configured or programmed to control the magnitude of the thrust and the rotational direction of the propeller 14 such that the watercraft 10 performs bow turning toward the target compass direction when the propeller 14 is located in each of the first and second steering positions. For example, the watercraft operating controller 30 controls the magnitude of the thrust in accordance with the amount of displacement in the compass direction of the watercraft 10. When the watercraft 10 is caused to perform bow turning in an identical direction regardless of whether the propeller 14 is located in the first steering position or the second steering position, the watercraft operating controller 30 controls the rotational direction of the propeller 14 such that the back-and-forth directional thrust, generated when the propeller 14 is located in the first steering position, is oriented opposite to that generated when the propeller 14 is located in the second steering position. Accordingly, a back-and-forth directional thrust component, oriented in an opposite direction to that generated when the propeller 14 is located in the first steering position, is generated when the propeller 14 is located in the second steering position.

FIG. 6 exemplifies the above in detail as follows: when the compass direction (T1) of the bow of the watercraft 10 is displaced rightward from the target compass direction (T0) under the influence of an external factor acting from the left side, if the propeller 14 is located in the first steering position, the watercraft operating controller 30 controls the rotational direction of the propeller 14 such that the watercraft 10 performs bow turning leftward about the center of gravity G of the watercraft 10. At this time, a thrust component is outputted rearward by the thrust to cause the watercraft 10 to perform bow turning and, thus, the watercraft 10 is displaced in position rearward. When 30 seconds elapses after the propeller 14 is turned to the first steering position, the watercraft operating controller 30 turns the propeller 14 to the second steering position. If the compass direction T1 of the bow of the watercraft 10 is displaced rightward from the target compass direction T0 when the propeller 14 is located in the second steering position, the watercraft operating controller 30 is configured or programmed to control the rotational direction of the propeller 14 such that the watercraft 10 performs bow turning leftward about the center of gravity G of the watercraft 10. Accordingly, a back-and-forth directional thrust component, oriented opposite to that generated when the propeller 14 is located in the first steering position, is generated when the propeller 14 is located in the second steering position. As a result, the watercraft 10 can is prevented from being displaced in the back-and-forth direction.

When the propeller 14 is turned from the first steering position to the second steering position, the watercraft operating controller 30 is configured or programmed to stop generation of a thrust until the propeller 14 reaches the second steering position. When the propeller 14 is turned from the second steering position to the first steering position, the watercraft operating controller 30 stops generation of a thrust until the propeller 14 reaches the first steering position. In other words, in the compass direction keeping control, even when the compass direction of the watercraft 10 is displaced from the target compass direction by a predetermined angle or greater, the watercraft operating controller 30 stops the driving of the electric motor 16 until the propeller 14 reaches the first steering position or until the propeller 14 reaches the second steering position. Accordingly, the watercraft 10 is prevented from being displaced in the back-and-forth direction. For example, in the compass direction keeping control, when the compass direction of the watercraft 10 is displaced from the target compass direction by a predetermined angle or greater, the watercraft operating controller 30 is configured or programmed to generate a thrust if the propeller 14 is turned either rightward or leftward by a rudder angle of greater than 55 degrees, for example.

In the watercraft operating system 100 according to the example embodiments explained above, the back-and-forth directional thrust component, oriented opposite to that generated when the propeller 14 is located in the first steering position, is generated when the propeller 14 is located in the second steering position by reversing the steering position of the propeller 14 at the predetermined time interval. Accordingly, the back-and-forth directional thrust component, generated by the thrust to cause the watercraft 10 to perform bow turning, is prevented from being oriented to only either the front side or the rear side in an eccentric manner. As a result, it is possible to enhance the position keeping accuracy in the compass direction keeping control.

Example embodiments of the present invention have been explained above. However, the present invention is not limited to the example embodiments described above and a variety of changes can be made without departing from the gist of the present invention.

The pivotable range of the lower portion 13 of the marine propulsion device 3 is not limited to that described in the example embodiments described above. For example, the lower portion 13 may be pivotable in the right-and-left direction within an angular range of 180 degrees (90 degrees on the right side and 90 degrees on the left side) or an angular range of 120 degrees (60 degrees on the right side and 60 degrees on the left side), for example. The second steering position may be set as a position obtained by reversing the first steering position in the back-and-forth direction. For example, when the first steering position is set as a position turned by 70 degrees with respect to the back-and-forth direction, the second steering position may be set as a position turned rightward by 110 degrees with respect to the back-and-forth direction, for example.

While example embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.