System for and Method of Controlling Watercraft

This application claims the benefit of priority to Japanese Patent Application No. 2024-075873 filed on May 8, 2024. The entire contents of this application are hereby incorporated herein by reference.

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

There has been known so far a technology for causing a watercraft to move sideways by controlling a net force of thrusts generated by a plurality of outboard motors. For example, Japan Laid-open Patent Application Publication No. 2022-99788 describes a watercraft equipped with two outboard motors. Each of the two outboard motors is able to be steered right and left. For example, when the watercraft is caused to move leftward, a system for controlling the watercraft controls the thrusts and the rudder angles of the two outboard motors such that the net force of the thrusts is oriented leftward while extending through the center of gravity of the watercraft. When the watercraft is caused to move rightward, the system for controlling the watercraft controls the thrusts and the rudder angles of the two outboard motors such that the net force of the thrusts is oriented rightward while extending through the center of gravity of the watercraft.

The technology described above requires a plurality of outboard motors for causing a watercraft to move sideways. Example embodiments of the present invention enable watercraft to move sideways by only one outboard motor mounted thereto.

A system according to an example embodiment of the present invention includes a bow thruster, an outboard motor as an only outboard motor attached to the watercraft, and a controller. The bow thruster includes a port oriented in an obliquely forward direction of the watercraft to jet a stream of water in the obliquely forward direction of the watercraft. The outboard motor is attached to the watercraft and steerable right and left. The controller is configured or programmed to control the outboard motor and the bow thruster to cause the watercraft to move sideways by a net force of a first thrust generated by the bow thruster and a second thrust generated by the outboard motor.

A method according to another example embodiment of the present invention relates to a method of controlling a watercraft including a bow thruster and an outboard motor as an only outboard motor attached thereto. The bow thruster includes a port oriented in an obliquely forward direction of the watercraft to jet a stream of water in the obliquely forward direction of the watercraft. The outboard motor is attached to the watercraft to be steerable right and left. The method includes controlling the outboard motor and the bow thruster to cause the watercraft to move sideways by a net force of a first thrust generated by the bow thruster and a second thrust generated by the outboard motor.

According to example embodiments of the present invention, the outboard motor and the bow thruster are controlled to cause the watercraft to move sideways by the net force of the first thrust generated by the bow thruster and the second thrust generated by the outboard motor. Accordingly, the watercraft is able to move sideways by the only one outboard motor mounted on the watercraft.

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.

Example embodiments of the present invention will be hereinafter explained with reference to drawings.is a perspective view of a watercraftincluding a system according to an example embodiment of the present invention. The watercraftincludes an outboard motoras the only outboard motor on the watercraft, and a bow thruster.

The outboard motoris attached to the stern of the watercraft. The outboard motorgenerates a thrust to propel the watercraft.is a side view of the outboard motor. The outboard motoris attached to the watercraftthrough a bracket. The bracketsupports the outboard motorsuch that the outboard motoris rotatable about a steering shaft. The steering shaftextends in an up-and-down direction of the outboard motor. The outboard motoris steerable right and left within a steering range including a straight sideways direction of the watercraft. The outboard motoris switchable from a neutral state in which a propelleris oriented in a straight rear direction of the watercraft, to a right steering state in which the propelleris oriented in a direction slanted rightward from the straight rear direction of the watercraft, and a left steering state in which the propelleris oriented in a direction slanted leftward from the straight rear direction of the watercraft.

The outboard motorincludes an engine, a driveshaft, a propeller shaft, and a shift mechanism. The enginegenerates the thrust to propel the watercraft. The engineincludes a crankshaft. The crankshaftextends in the up-and-down direction of the outboard motor. The driveshaftis connected to the crankshaft. The driveshaftextends in the up-and-down direction of the outboard motor. The propeller shaftextends in a front-and-back direction of the outboard motor. The propeller shaftis connected to the driveshaftthrough the shift mechanism. The propeller shaftis provided with the propellerattached thereto.

The shift mechanismincludes a forward moving gear, a rearward moving gear, and a dog clutch. When gear engagement of each gear,is switched by the dog clutch, the direction of rotation transmitted from the drive shaftto the propeller shaftis switched. Movement of the watercraftis thus switched between forward movement and rearward movement.

More specifically, the shift mechanismis switchable among a forward moving state, a rearward moving state, and a neutral state. When the shift mechanismis in the forward moving state, the dog clutchis connected to the forward moving gear. Accordingly, the rotation of the driveshaftis transmitted to the propeller shaftso as to rotate the propeller shaftin a forward moving direction. When the shift mechanismis in the rearward moving state, the dog clutchis connected to the rearward moving gear. Accordingly, the rotation of the driveshaftis transmitted to the propeller shaftso as to rotate the propeller shaftin a rearward moving direction. When the shift mechanismis in the neutral state, the dog clutchis released from being connected to each of the forward moving gearand the rearward moving gear. Accordingly, the rotation of the driveshaftis not transmitted to the propeller shaft.

is a top view schematically showing a configuration of the watercraft. As shown in, the bow thrusteris attached to the watercraftto jet or eject a stream of water in an obliquely forward direction of the watercraft. The bow thrusterincludes a first port, a second port, and a water stream generator. The first portis provided in a right lateral surface of the watercraft. The first portis oriented in a right front direction of the watercraft. The second portis provided in a left lateral surface of the watercraft. The second portis oriented in a left front direction of the watercraft. Each of the first and second portsandis fixed in orientation.

The water stream generatorgenerates the stream of water to be jetted from one of the first and second portsand. The water stream generatorincludes, for instance, a propeller and a motor. Alternatively, the water stream generatormay include a pump. The bow thrusterjets the stream of water from the first portin the right front direction of the watercraft. The bow thrusterjets the stream of water from the second portin the left front direction of the watercraft.

is a schematic diagram showing a configuration of a system for controlling the watercraft. As shown in, the outboard motorincludes a shift actuatorand a steering actuator. The shift actuatoris connected to the dog clutchof the shift mechanism. The shift actuatoractuates the dog clutchto switch gear engagement of each gear,. Movement of the watercraftis thus switched between forward movement and rearward movement. The shift actuatormay be, for instance, an electric motor. However, the shift actuatormay be another type of actuator such as an electric cylinder, a hydraulic motor, or a hydraulic cylinder.

The steering actuatoris connected to the outboard motor. The steering actuatorrotates the outboard motorabout the steering shaft. The outboard motoris thus changed in rudder angle. The rudder angle refers to an angle of the propeller shaftwith respect to the front-and-back direction of the outboard motor. The steering actuatormay be, for instance, an electric motor. However, the shift actuatormay be another type of actuator such as an electric cylinder, a hydraulic motor, or a hydraulic cylinder.

The outboard motorincludes an ECU (Electric Control Unit). The ECUincludes 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 ECUhas stored therein programs and data to control the outboard motor. The ECUcontrols the engine.

The system includes a steering wheel, a remote controller, and a joystick. As shown in, the steering wheel, the remote controller, and the joystickare disposed in a cockpit of the watercraft.

The steering wheelallows a user to manipulate the turning direction of the watercraft. The steering wheelincludes a sensor. The sensoroutputs a steering signal indicating the operating direction and the operating amount of the steering wheel.

The remote controllerincludes a throttle leverand a sensor. The throttle leverenables the user to regulate the magnitude of the thrust generated by the outboard motor. Additionally, the throttle leverenables the user to switch the direction of the thrust generated by the outboard motorbetween the front and rear directions. The throttle leveris operable from a neutral position to a forward moving directional side and a rearward moving directional side. The neutral position is a position located between the forward moving directional side and the rearward moving directional side. The sensoroutputs a throttle signal indicating the operating direction and the operating amount of the throttle lever.

The joystickis operable by the user to instruct the watercraftto perform one of a plurality of moving modes. The joystickis tiltable from a neutral position in at least four directions of front, rear, right, and left. Moving the watercraftin four or more directions, and furthermore, all directions may be instructible by the joystick. The joystickis rotatable about a rotational axis Ax. In other words, the joystickis operable to be twisted clockwise and counterclockwise about the rotational axis Axfrom the middle position.

The joystickincludes a sensor. The sensoroutputs a joystick signal indicating how the joystickhas been operated. The joystick signal includes the tilt direction and the tilt amount of the joystick. The joystick signal includes the twist direction and the twist amount of the joystickas well.

The system includes a controller. The controllerincludes a processor such as a CPU and memories such as a RAM and a ROM. The controllerhas stored programs and data therein to control the outboard motorand the bow thruster. The controlleris connected to the ECUand the bow thrusterthrough wired or wireless communication. The controlleris connected to the steering wheel, the remote controller, and the joystick.

The controllerreceives the steering signal from the sensor. The controllerreceives the throttle signal from the sensor. The controllerreceives the joystick signal from the sensor. The controlleroutputs command signals to the ECUbased on the signals inputted thereto from the sensors,, and. The command signals are transmitted to the engine, the shift actuator, and the steering actuatorthrough the ECU. Additionally, the controlleroutputs a command signal to the bow thruster.

The controlleroutputs a shift command for the shift actuatorin accordance with the operating direction of the throttle lever. In response, shifting between forward movement and rearward movement by the outboard motoris made. The controlleroutputs a throttle command for the enginein accordance with the operating amount of the throttle lever. The ECUcontrols the thrust generated by the outboard motorin accordance with the throttle command. It should be noted that the throttle signal, outputted from the sensor, may be directly inputted to the ECU. The ECUmay output the throttle command to the enginein accordance with the throttle signal inputted thereto from the sensor.

The controlleroutputs a command signal for the steering actuatorin accordance with the operating direction and the operating amount of the steering wheel. When the steering wheelis operated leftward from the neutral position, the controllercontrols the steering actuatorsuch that the outboard motoris in the left steering state. Accordingly, the watercraftturns leftward.

When the steering wheelis operated rightward from the neutral position, the controllercontrols the steering actuatorsuch that the outboard motoris in the right steering state. Accordingly, the watercraftturns rightward. Additionally, the controllercontrols the rudder angle of the outboard motorin accordance with the opening amount of the steering wheel.

The controlleroutputs command signals to the engine, the shift actuator, the steering actuator, and the bow thrusterin accordance with the tilt direction and the tilt amount of the joystick. The controllercontrols the engine, the shift actuator, the steering actuator, and the bow thrustersuch that the watercrafttranslates at a velocity corresponding to the tilt amount of the joystickin a direction corresponding to the tilt direction of the joystick.

When the joystickis being tilted forward, the controllercauses the watercraftto move forward by the thrust generated by the outboard motor(fore surging mode). When the joystickis being tilted rearward, the controllercauses the watercraftto move rearward by the thrust generated by the outboard motor(aft surging mode).

When the joystickis being tilted leftward or rightward, the controllercauses the watercraftto move leftward or rightward (swaying mode). In the swaying mode, the controllercontrols the outboard motorand the bow thrusterto cause the watercraftto move sideways by a net force of the thrust generated by the bow thruster(first thrust) and the thrust generated by the outboard motor(second thrust).

For example, when the joystickis being tilted leftward, the controllersets the left direction as a target moving direction. When the left direction is set as the target moving direction, as shown in, the controllercauses the bow thrusterto jet a stream of water right-forward from the first portwhile setting the outboard motorto the right steering state. Accordingly, the controllercauses the bow thrusterto generate the first thrust (F) oriented left-rearward while causing the outboard motorto generate the second thrust (F) oriented left-forward. The controllercontrols the magnitude of the first thrust Fgenerated by the bow thruster, the magnitude of the second thrust Fgenerated by the outboard motor, and the rudder angle of the outboard motorsuch that the net force (F) of the first thrust Fgenerated by the bow thrusterand the second thrust Fgenerated by the outboard motoris oriented in the left direction of the watercraft. Accordingly, the watercrafttranslates straight leftward.

When the joystickis being tilted left-rearward, the controllersets the left rear direction as the target moving direction. When the left rear direction is set as the target moving direction, as shown in, the controllercauses the bow thrusterto jet a stream of water right-forward from the first portwhile setting the outboard motorto the right steering state. Accordingly, the controllercauses the bow thrusterto generate the first thrust Foriented left-rearward while causing the outboard motorto generate the second thrust Foriented left-forward. The controllercontrols the magnitude of the first thrust Fgenerated by the bow thruster, the magnitude of the second thrust Fgenerated by the outboard motor, and the rudder angle of the outboard motorsuch that the net force Fof the first thrust Fgenerated by the bow thrusterand the second thrust Fgenerated by the outboard motoris oriented in the left rear direction of the watercraft. Accordingly, the watercrafttranslates left-rearward.

When the joystickis being tilted left-forward, the controllersets the left front direction as the target moving direction. When the left front direction is set as the target moving direction, as shown in, the controllercauses the bow thrusterto jet a stream of water right-forward from the first portwhile setting the outboard motorto the right steering state. Accordingly, the controllercauses the bow thrusterto generate the first thrust Foriented left-rearward while causing the outboard motorto generate the second thrust Foriented left-forward. The controllercontrols the magnitude of the first thrust Fgenerated by the bow thruster, the magnitude of the second thrust Fgenerated by the outboard motor, and the rudder angle of the outboard motorsuch that the net force Fof the first thrust Fgenerated by the bow thrusterand the second thrust Fgenerated by the outboard motoris oriented in the left front direction of the watercraft. Accordingly, the watercrafttranslates left-forward.

The controllercontrols the engine, the shift actuator, the steering actuator, and the bow thrustersuch that the watercraftturns at a velocity corresponding to the twisted amount of the joystickin a direction corresponding to the twisted direction of the joystick(turning mode).

For example, when the joystickis twisted clockwise, and tilted leftward, the controllersets the right turning direction as a target turning direction. When the right turning direction is set as the target turning direction while the outboard motoris in the right steering state, the controllercauses the bow thrusterto jet a stream of water right-forward from the first portwhile keeping the outboard motorin the right steering state. As shown in, the controllercontrols the magnitude of the first thrust Fgenerated by the bow thruster, the magnitude of the second thrust Fgenerated by the outboard motor, and the rudder angle of the outboard motorsuch that the net force Fof the first thrust Fgenerated by the bow thrusterand the second thrust Fgenerated by the outboard motorextends through a position located behind the center of resistance (center of gravity) Gof the watercraft. Accordingly, the watercraftturns rightward.

When the joystickis twisted counterclockwise, and tilted leftward, the controllersets the left turning direction as the target turning direction. When the left turning direction is set as the target turning direction while the outboard motoris in the right steering state, the controllercauses the bow thrusterto jet a stream of water right-forward from the first portwhile keeping the outboard motorin the right steering state. As shown in, the controllercontrols the magnitude of the first thrust Fgenerated by the bow thruster, the magnitude of the second thrust Fgenerated by the outboard motor, and the rudder angle of the outboard motorsuch that the net force Fof the first thrust Fgenerated by the bow thrusterand the second thrust Fgenerated by the outboard motorextends through a position located ahead of the center of resistance Gof the watercraft. Accordingly, the watercraftturns leftward.

When the joystickis being tilted rightward, the controllersets the right direction as the target moving direction. When the right direction is set as the target moving direction, as shown in, the controllercauses the bow thrusterto jet a stream of water left-forward from the second portwhile setting the outboard motorto the left steering state. Accordingly, the controllercauses the bow thrusterto generate the first thrust Foriented right-rearward while causing the outboard motorto generate the second thrust Foriented right-forward. The controllercontrols the magnitude of the first thrust Fgenerated by the bow thruster, the magnitude of the second thrust Fgenerated by the outboard motor, and the rudder angle of the outboard motorsuch that the net force Fof the first thrust Fgenerated by the bow thrusterand the second thrust Fgenerated by the outboard motoris oriented in the right direction of the watercraft. Accordingly, the watercrafttranslates straight rightward.

When the joystickis being tilted right-rearward, the controllersets the right rear direction as the target moving direction. When the right rear direction is set as the target moving direction, as shown in, the controllercauses the bow thrusterto jet a stream of water left-forward from the second portwhile setting the outboard motorto the left steering state. Accordingly, the controllercauses the bow thrusterto generate the first thrust Foriented right-rearward while causing the outboard motorto generate the second thrust Foriented right-forward. The controllercontrols the magnitude of the first thrust Fgenerated by the bow thruster, the magnitude of the second thrust Fgenerated by the outboard motor, and the rudder angle of the outboard motorsuch that the net force Fof the first thrust Fgenerated by the bow thrusterand the second thrust Fgenerated by the outboard motoris oriented in the right rear direction of the watercraft. Accordingly, the watercrafttranslates right-rearward.

When the joystickis being tilted right-forward, the controllersets the right front direction as the target moving direction. When the right front direction is set as the target moving direction, as shown in, the controllercauses the bow thrusterto jet a stream of water left-forward from the second portwhile setting the outboard motorto the left steering state. Accordingly, the controllercauses the bow thrusterto generate the first thrust Foriented right-rearward while causing the outboard motorto generate the second thrust Foriented right-forward. The controllercontrols the magnitude of the first thrust Fgenerated by the bow thruster, the magnitude of the second thrust Fgenerated by the outboard motor, and the rudder angle of the outboard motorsuch that the net force Fof the first thrust Fgenerated by the bow thrusterand the second thrust Fgenerated by the outboard motoris oriented in the right front direction of the watercraft. Accordingly, the watercrafttranslates right-forward.

When the joystickis twisted clockwise, and tilted rightward while the outboard motoris in the right steering state, as shown in, the controllercauses the bow thrusterto jet a stream of water left-forward from the second portwhile keeping the outboard motorin the left steering state. The controllercontrols the magnitude of the first thrust Fgenerated by the bow thruster, the magnitude of the second thrust Fgenerated by the outboard motor, and the rudder angle of the outboard motorsuch that the net force Fof the first thrust Fgenerated by the bow thrusterand the second thrust Fgenerated by the outboard motorextends through a position located ahead of the center of resistance Gof the watercraft. Accordingly, the watercraftturns rightward.

When the joystickis twisted counterclockwise, and tilted rightward while the outboard motoris in the left steering state, as shown in, the controllercauses the bow thrusterto jet a stream of water left-forward from the second portwhile keeping the outboard motorin the left steering state. The controllercontrols the magnitude of the first thrust Fgenerated by the bow thruster, the magnitude of the second thrust Fgenerated by the outboard motor, and the rudder angle of the outboard motorsuch that the net force Fof the first thrust Fgenerated by the bow thrusterand the second thrust Fgenerated by the outboard motorextends through a position located behind the center of resistance Gof the watercraft. Accordingly, the watercraftturns leftward.

In the system for controlling the watercraftaccording to an example embodiment, the outboard motorand the bow thrusterare controlled to cause the watercraftto move sideways by the net force Fof the first thrust Fgenerated by the bow thrusterand the second thrust Fgenerated by the outboard motor. Accordingly, the watercraftis able to move sideways by only one outboard motoron the watercraft.

Additionally, when the watercraft user slightly adjusts the movement of the watercraftby oblique movement, turning, or so forth while causing the watercraftto move sideways by the joystick, the outboard motoris kept approximately constant in orientation. Thus, smooth transition is enabled between the plurality of moving modes. For example, during the leftward movement of the watercraft, when the watercraft user slightly adjusts the movement of the watercraftby obliquely leftward movement or leftward turning while tilting the joystickleftward, the outboard motoris in the right steering state all the while. On the other hand, during the rightward movement of the watercraft, when the watercraft user slightly adjusts the movement of the watercraftby obliquely rightward movement or rightward turning while tilting the joystickrightward, the outboard motoris in the left steering state all the while. Because of this, the outboard motoris not changed much in rudder angle in transition between the moving modes. Thus, smooth transition is enabled between the plurality of moving modes.

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 outboard motoris not limited in configuration to the example embodiments described above and may be changed. For example, the outboard motormay include an electric motor instead of the engine. In the example embodiments described above, the joystickhas been exemplified as an operating device to instruct one of the plurality of moving modes. However, the operating device is not limited to the joystickand may be changed. For example, the operating device may be another type of device such as a switch or a touch screen. The moving modes may be changed from one to another, not by a manual operation performed on the operating device by the watercraft user, but by an automated watercraft operation performed by the controller.

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.