BOAT CONTROL SYSTEM AND BOAT

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2024-006627 filed on Jan. 19, 2024. The entire contents of this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION
1. Field of the Invention

The technologies disclosed herein relate to boat control systems and boats.

2. Description of the Related Art

A system for controlling the movement of a boat is known and includes a plurality of boat propulsion devices and a controller that controls the thrust and steering angle of each of the plurality of boat propulsion devices. For example, a technology for “coordinated control” has been proposed that coordinates the driving of the plurality of boat propulsion devices installed on a boat based on driving information (see JP 2022-090257 A).

SUMMARY OF THE INVENTION

In a boat equipped with a plurality of boat propulsion devices, there are cases where unintended differences between the outputs of the plurality of boat propulsion devices may occur because of factors such as manufacturing errors, adjustment errors, deterioration over time, and differences in conditions due to warm-up operations. In such cases, the boat body may turn in a way that is unintended by the steering person, which is confusing.

Example embodiments of the present invention disclose technologies that can solve one or more of the above-mentioned problems.

The technologies disclosed herein can be implemented, e.g., in the following example embodiments.

A boat control system for controlling a boat including a boat body includes a plurality of boat propulsion devices each steerable 180 degrees or more about a steering axis, a controller configured or programmed to control a thrust and a steering angle of the plurality of boat propulsion devices, and an operator to accept an operation request to move the boat body and output an operation signal to the controller. The plurality of boat propulsion devices includes a first boat propulsion device including a first drive source to generate a power to propel the boat body and a first output sensor to detect an output of the first drive source and output a detection signal to the controller, and a second boat propulsion device including a second drive source to generate a power to propel the boat body and a second output sensor to detect an output of the second drive source and output a detection signal to the controller, wherein the controller is configured or programmed to perform, when the controller determines that the output of the first drive source and the output of the second drive source have a difference when the operator is not accepting an operation request to turn the boat body, an output adjustment process to change the output of at least one of the first drive source and the second drive source so as to cancel the difference in the outputs.

The technologies disclosed herein can be implemented in various example embodiments, e.g., boats, control devices provided on boats, control methods for boats, computer programs for implementing functions of those devices or methods, and non-transitory recording media including the computer programs.

The example embodiments and technologies disclosed herein facilitate the steering of boats as intended by the steering person with a simple configuration.

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 perspective view schematically illustrating a configuration of a boat according to a first example embodiment of the present invention.

FIG. 2 is a side view schematically illustrating a configuration of a first outboard motor according to the first example embodiment of the present invention.

FIG. 3 is a front view illustrating a configuration of a joystick device according to the first example embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of a steering system according to the first example embodiment of the present invention.

FIG. 5 is a schematic view illustrating a control of the outboard motors by a joystick according to the first example embodiment of the present invention.

FIG. 6 is a flowchart illustrating a flow of an outboard motor control at a start of a joystick mode according to the first example embodiment of the present invention.

FIG. 7 is a schematic view illustrating a change in the output of the outboard motors due to an output adjustment process at the start of the joystick mode according to the first example embodiment of the present invention.

FIG. 8 is a schematic view illustrating the change in the output of the outboard motors due to the output adjustment process at the start of the joystick mode according to the first example embodiment of the present invention.

FIG. 9 is a schematic view illustrating the change in the output of the outboard motors due to the output adjustment process at the start of the joystick mode according to the first example embodiment of the present invention.

FIG. 10 is a schematic view illustrating the change in the output of the outboard motors due to the output adjustment process at the start of the joystick mode according to the first example embodiment of the present invention.

FIG. 11 is a flowchart illustrating the flow of the outboard motor control when the boat is controlled in a stay point mode according to the first example embodiment of the present invention.

FIG. 12 is a schematic view illustrating the change in the output of the outboard motors due to the output adjustment process when the boat is controlled in the stay point mode according to the first example embodiment of the present invention.

FIG. 13 is a schematic view illustrating the change in the output of the outboard motors due to the output adjustment process when the boat is controlled in the stay point mode according to the first example embodiment of the present invention.

FIG. 14 is a block diagram illustrating a configuration of a steering system according to a second example embodiment of the present invention.

FIG. 15 is a flowchart illustrating a flow of an outboard motor control at a start of a joystick mode according to the second example embodiment of the present invention.

FIG. 16 is a schematic view illustrating a change in the output of the outboard motors due to the output adjustment process at the start of the joystick mode and the steering of a third outboard motor according to the second example embodiment of the present invention.

FIG. 17 is a schematic view illustrating the change in the output of the outboard motors due to the output adjustment process at the start of the joystick mode and the steering of the third outboard motor according to the second example embodiment of the present invention.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

A first example embodiment will be described with reference to FIGS. 1 to 13. As shown in FIGS. 1 and 4, a boat 1A of the first example embodiment includes a boat body 10, two outboard motors 100P, 100S (an example of a boat propulsion device), a steering device 200 (an example of an operator) that accepts an operation request to steer the boat 1A, and a controller 300 configured or programmed to control a thrust and a steering angle of the outboard motors 100P, 100S, a position sensor 260 to detect a position of the boat body 10, and an azimuth sensor 270 (an example of a turning sensor) to detect a turning of the boat body 10. One of the two outboard motors 100P, 100S is a first outboard motor 100P (an example of a first boat propulsion device) including an engine 120P (an example of a first drive source) and an output sensor 129P (an example of a first output sensor) to detect an output of the engine 120P, and the other is a second outboard motor 100S (an example of a second boat propulsion device) including an engine 120S (an example of a second drive source) and an output sensor 129S (an example of a second output sensor) to detect an output of the engine 120S. The outboard motors 100P, 100S, the steering device 200, the controller 300, the position sensor 260, and the azimuth sensor 270 are elements of the boat control system 400A.

FIG. 1 and other figures to follow show arrows representing each direction with respect to the position of boat 1A. More specifically, each drawing shows arrows representing the front direction (FRONT), rear direction (REAR), left direction (LEFT), right direction (RIGHT), upper direction (UPPER), and lower direction (LOWER), respectively, as appropriate. The front-rear direction, left-right direction, and upper-lower (vertical) direction are orthogonal to each other.

The boat body 10 of the boat 1A is for occupants to ride. As shown in FIG. 1, the boat body 10 includes a pilot seat 12.

The outboard motors 100P, 100S are attached to the stern of the boat body 10 to generate thrust to propel the boat body 10. As shown in FIG. 1, the first outboard motor 100P is located on the port side of the boat body 10, and the second outboard motor 100S is located on the starboard side of the boat body 10. As shown in FIG. 1, The configuration of the first outboard motor 100P will be described in detail below. Since the second outboard motor 100S has the same structure as the first outboard motor 100P, identical elements or parts are marked with identical symbols, and descriptions thereof are omitted. When the elements provided in the first outboard motor 100P and those provided in the second outboard motor 100S are described separately, “P” is added to the end of the sign of the elements provided in the first outboard motor 100P, and “S” is added to the end of the sign of the elements provided in the second outboard motor 100S.

The first outboard motor 100P is attached to the stern of the boat body 10 via a bracket 180. The outboard motor 100P is supported by the bracket 180 in a displaceable range from a tilt-down state in which the propeller 140, which is described below, is positioned underwater to a tilt-up state in which the propeller 140 is positioned above the water surface. In the following, the outboard motor 100P in the reference attitude (attitude shown in FIG. 2) will be described unless otherwise noted. The reference attitude is one in which the rotation axis Ad of the drive shaft 124, which is described below, extends in the upper-lower direction and the rotation axis Ap of the propeller shaft 142 extends in the front-rear direction.

As shown in FIG. 2, the outboard motor 100P includes an upper unit 110 attached to the boat body 10 via the bracket 180, a lower unit 130 arranged below the upper unit 110, and a steering mechanism 160P interposed between the upper unit 110 and the lower unit 130.

The upper unit 110 includes a cowl 112, an upper case 114, an engine 120P, a drive shaft 124, an electronic control unit (ECU) 190P, and an output sensor 129P, as shown in FIG. 2.

The cowl 112 is a housing located on top of the outboard motor 100P. The upper case 114 is a housing arranged below the cowl 112 and is attached to the boat body 10 via the bracket 180.

The engine 120 is a prime mover to generate power to drive the outboard motor 100P and is located inside the cowl 112. The engine 120 includes an engine body 121 and an intake device 125. The engine body 121 has a known configuration including a cylinder block (not shown) provided with a plurality of cylinders (not shown), a piston (not shown) disposed inside each cylinder and reciprocating as a mixture of fuel and air is burned, and a crankshaft 122 rotating as the piston reciprocates. The crankshaft 122 is arranged in an attitude extending in the upper-lower direction as shown in FIG. 2. The intake device 125 has a known configuration including an intake channel 126 that supplies air to the inside of the cylinder block, a throttle valve 127P provided in the intake channel 126, and a throttle actuator 128P that controls the opening (throttle opening) of the throttle valve 127P. The throttle actuator 128P includes, e.g., an electric motor. The throttle actuator 128P operates the throttle valve 127P to change the throttle opening. The increase in throttle opening increases the flow rate of air supplied to the inside of the cylinder block, thus increasing the output of the engine 120 (rotation speed of the crankshaft 122). The decrease in throttle opening decreases the flow rate of air supplied to the inside of the cylinder block, thus decreasing the output of the engine 120 (rotation speed of the crankshaft 122). The throttle actuator 128P is communicatively connected to the ECU 190P.

The drive shaft 124 is a rod-shaped member, connected to the lower end of the crankshaft 122 and positioned in an attitude in which its rotation axis Ad extends in the upper-lower direction. The drive shaft 124 rotates along with the rotation of the crankshaft 122. Most of the drive shaft 124 is located inside the cowl 112 and the upper case 114. The lower end of the drive shaft 124 protrudes downward from the upper case 114 and extends into the inside of the lower unit 130.

The ECU 190P is located inside the cowl 112. The ECU 190P includes a processor such as a central processing unit (CPU) and a storage device such as a read only memory (ROM) and a random access memory (RAM). The storage device stores various programs and data to control the outboard motor 100P.

The output sensor 129P detects the output of the engine 120P. In this example embodiment, the rotation speed of the engine 120P, i.e., the rotation speed of the crankshaft 122 provided in the engine 120P, is used as an indicator of the output of the engine 120P. The output sensor 129P is, e.g., a crankshaft sensor that detects the rotation angle of the crankshaft 122. The output sensor 129P outputs an engine output signal (an example of a detection signal) corresponding to the rotation speed of the crankshaft 122. The output sensor 129P is communicatively connected to the ECU 190P.

The lower unit 130 includes a lower case 132, a propeller 140, a propeller shaft 142, and a shift mechanism 150P, as shown in FIG. 2.

The lower case 132 is a housing arranged below the upper case 114.

The propeller 140 is a rotating member including a plurality of blades and generates thrust by rotating. The propeller shaft 142 is a rod-shaped member and is arranged in a attitude extending in a front-rear direction. The rear end of the propeller shaft 142 protrudes outside the lower case 132, and the remaining portion is housed within the lower case 132. The propeller 140 is attached to the rear end of the propeller shaft 142. As the propeller shaft 142 rotates about the rotation axis Ap, the propeller 140 also rotates.

The shift mechanism 150P is connected to the lower end of the drive shaft 124 and to the front end of the propeller shaft 142. The shift mechanism 150P has a known configuration including, e.g., a forward gear, a backward gear, and a clutch. By switching the engagement of the clutch with the two gears, the direction of rotation transmitted from the drive shaft 124 to the propeller shaft 142 is switched.

The lower unit 130 further includes a shift actuator 152P that switches the shift state of the outboard motor 100P. The shift actuator 152P includes, e.g., an electric motor. The shift actuator 152P is connected to a clutch provided in the shift mechanism 150P and is configured to actuate the clutch to switch the shift state of the outboard motor 100P among the forward movement, backward movement, and neutral states by switching engagement with the forward and the backward gear. The forward movement state is a state in which the clutch engages the forward gear, the rotation of the drive shaft 124 is transmitted to the propeller shaft 142 as forward rotation, and the propeller 140, which rotates in the forward direction with the propeller shaft 142, generates thrust in the forward direction. The backward movement state is a state in which the clutch engages the backward gear, the rotation of the drive shaft 124 is transmitted to the propeller shaft 142 as reverse rotation, and the propeller 140, which rotates in the reverse direction with the propeller shaft 142, generates thrust in the backward direction. The neutral state is a state in which the clutch is not engaged with either the forward gear or the backward gear, so that the rotation of the drive shaft 124 is not transmitted to the propeller shaft 142 and the propeller 140 does not generate thrust. The shift actuator 152P is communicatively connected to the ECU 190P.

The steering mechanism 160P changes the direction of the thrust generated by the outboard motor 100P and is configured to rotate the lower unit 130 relative to the upper unit 110. As shown in FIG. 2, for example, the steering mechanism 160P has a known configuration including a pinion 161 that rotates along with the lower unit 130, a steering shaft 162 that is attached to the pinion 161 and through which the drive shaft 124 can be inserted, and a rack 163 that engages the pinion 161 and moves linearly. The steering mechanism 160P is driven by a steering actuator 164P (see also FIG. 4). The steering actuator 164P is a drive to linearly move the rack 163, e.g., the steering actuator 164P includes an electric motor. When the rack 163 is moved linearly by the driving force of the steering actuator 164P, the pinion 161 rotates. This rotation causes the lower unit 130 to rotate around the rotation axis Ad of the drive shaft 124 as the steering shaft. In conjunction with this rotation, the propeller shaft 142 rotates about the rotation axis Ad. The steering actuator 164P is communicatively connected to the ECU 190P.

In this specification, the steering angle is defined as follows. As shown in FIG. 5, the steering angle is 0° when the orientation of the lower unit 130 is such that the rotation axis Ap of the propeller shaft 142 is parallel to the centerline C of the boat body 10 and the propeller 140 is directed rearward. Then, the clockwise rotation of the lower unit 130, viewed from above, is referred to as the turning in the positive direction, and the counterclockwise rotation is referred to as the turning in the negative direction. The rotation angle of the propeller shaft 142 from the 0° steering angle position is referred to as the turning angle. The lower unit 130 can be turned ±180° from the 0° steering angle position, or 180° clockwise and counterclockwise, respectively. In other words, the lower unit 130 can be turned from a steering angle of +180°, back to a steering angle of +0°, and then to a steering angle of −180°, and from a steering angle of −180°, back to a steering angle of +0°, and then to a steering angle of +180°. That is, the maximum range (total steering angle) over which the lower unit 130 can be turned is 360°.

The steering device 200 is located near the pilot seat 12 and accepts operation requests by the steering person to control the movement of the boat body 10. The steering device 200 includes a steering wheel 210, shift/throttle levers 220P, 220S, and a joystick device 230, as shown in FIGS. 1 and 4. The steering wheel 210 accepts operation requests by the steering person to instruct the turning direction of the boat body 10 and is rotatable. As shown in FIG. 4, a steering sensor 212 is connected to the steering wheel 210. The steering sensor 212 outputs a steering signal indicating the direction and angle of rotation of the steering wheel 210.

The shift/throttle levers 220P, 220S are devices that accept operation requests by the steering person to instruct the magnitude of thrust and shift state switching of the two outboard motors 100P, 100S, respectively. The shift/throttle levers 220P, 220S can be moved forward and backward from the neutral position. As shown in FIG. 4, throttle sensors 222P, 222S are connected to the shift/throttle levers 220P, 220S, respectively. The throttle sensors 222P, 222S output throttle signals indicating the operation direction and operation amount of the shift/throttle levers 220P, 220S, respectively.

The joystick device 230 includes a rod-shaped joystick 232 that accepts operation requests by the steering person to control the movement of the boat body 10 and a joystick base 234 that supports the joystick 232 in a tiltable and twistable manner, as shown in FIG. 3 (an example of the mode switch). The joystick 232 is urged by a spring or other force source to automatically return to the default position (where the joystick 232 is upright) when no operating force is applied. The joystick 232 can be tilted forward, backward, leftward, rightward, and diagonally from the default position, and can be operated by twisting clockwise and counterclockwise, and can be tilted while twisting.

The joystick base 234 includes a joystick button 240, a stay point button 241, a drift point button 242, and a fish point button 243. The joystick button 240 is used to switch the steering mode between the normal steering mode, in which the steering wheel 210 and the shift/throttle levers 220P, 220S are used to control the boat, and the joystick mode, in which the joystick device 230 is used to control the boat. The stay point button 241, the drift point button 242, and the fish point button 243 are buttons to transition to the set point mode described below.

The joystick base 234 further includes a joystick sensor 250 connected to the joystick 232 (see FIG. 4). The joystick sensor 250 outputs joystick signals indicating the tilt direction and tilt amount (e.g., tilt angle) and the twist direction and twist amount (e.g., twist angle) of the joystick 232. The joystick sensor 250 further outputs an operation signal indicating that any of the buttons 240, 241, 242, 243 was pushed.

The position sensor 260 detects the position of the boat body 10. The position sensor 260 may be a Global Navigation Satellite System (GNSS) receiver, such as the Global Positioning System (GPS). The position sensor 260 detects the position of the boat body 10 and outputs a position signal indicating the position of the boat body 10.

The azimuth sensor 270 detects the azimuth of the boat body 10. The azimuth sensor 270 includes, e.g., an inertial measurement unit (IMU). The azimuth sensor 270 detects the azimuth of the boat body 10 and outputs the azimuth signal (an example of the detection signal) indicating the azimuth of the boat body 10.

The controller 300 includes, e.g., a CPU, a multi-core CPU, and a programmable device (e.g., field programmable gate array (FPGA), programmable logic device (PLD)). The controller 300 controls the operation of the boat body 10. In other words, the controller 300 controls the magnitude and direction of the thrust of the outboard motors 100P, 100S, respectively, according to the operations accepted by the steering device 200.

The controller 300 includes a storage device. The storage device includes, e.g., a ROM, a RAM, a hard disk drive (HDD), and a solid-state drive (SDD). The storage device stores various programs and data and is used as a work area or data storage area when executing various processes. For example, a computer program for executing the steering angle change process described below is stored in the storage device. This computer program is provided, e.g., in a computer-readable recording medium such as a CD-ROM, DVD-ROM, or USB memory (not shown), or it can be obtained from an external device (e.g., a server in the cloud) via a communication interface (not shown) and stored in a storage device in a manner that can be executed on the boat control system 400A.

The controller 300 is communicatively connected to the ECUs 190P, 190S, the position sensor 260, the azimuth sensor 270, the steering sensor 212, the throttle sensors 222P, 222S, and the joystick sensor 250.

The controller 300 obtains the position and speed of the boat body 10 by receiving position signals from the position sensor 260. The controller 300 obtains the azimuth of the boat body 10 by receiving azimuth signals from the azimuth sensor 270. The controller 300 obtains the engine outputs of the engines 120P, 120S by receiving the engine output signals from the output sensors 129P, 129S via the ECUs 190P, 190S.

The controller 300 receives steering signals from the steering sensor 212, throttle signals from the throttle sensors 222P, 222S, and joystick signals and operation signals from the joystick sensor 250. Based on these signals, the controller 300 outputs command signals to the ECUs 190P, 190S. The ECU 190P outputs command signals to the throttle actuator 128P, the shift actuator 152P, and the steering actuator 164P according to the command signals from the controller 300. The ECU 190S outputs command signals to the throttle actuator 128S, the shift actuator 152S, and the steering actuator 164S according to the command signal from the controller 300.

In this example embodiment, the controller 300 sets the steering mode to the normal steering mode by default. The normal steering mode is a mode in which the boat is primarily operated using the steering wheel 210 and the shift/throttle levers 220P, 220S.

In the normal steering mode, the controller 300 receives steering signals from the steering sensor 212 and throttle signals from the throttle sensors 222P, 222S. Based on these signals, the controller 300 outputs command signals to the throttle actuators 128P, 128S, the shift actuators 152P, 152S, and the steering actuators 164P, 164S via the ECUs 190P, 190S.

For example, the controller 300 outputs a command signal corresponding to the operating direction of the shift/throttle lever 220P to the shift actuator 152P. Based on the received command signal, the shift actuator 152P activates the clutch of the shift mechanism 150P to switch the engagement of the clutch with respect to the forward gear and the backward gear. As a result, the shift state of the first outboard motor 100P is switched among the forward movement state, the backward movement state, and the neutral state. Similarly, the controller 300 outputs a command signal corresponding to the operating direction of the shift/throttle lever 220S to the shift actuator 152S. Based on the received command signal, the shift actuator 152S activates the clutch of the shift mechanism 150S to switch the engagement of the clutch with respect to the forward gear and the backward gear. As a result, the shift state of the second outboard motor 100S is switched among the forward movement state, the backward movement state, and the neutral state.

The controller 300 also outputs a command signal corresponding to the operating amount of the shift/throttle lever 220P to the throttle actuator 128P. The throttle actuator 128P changes the opening of the throttle valve 127P based on the received command signal. This changes the output (rotation speed of the crankshaft 122) of the engine 120P, which in turn changes the rotation speed of the propeller shaft 142 and propeller 140, thus changing the magnitude of the thrust generated by the first outboard motor 100P. Similarly, the controller 300 outputs a command signal corresponding to the operating amount of the shift/throttle lever 220S to the throttle actuator 128S. The throttle actuator 128S changes the opening of the throttle valve 127S based on the received command signal. This changes the magnitude of the thrust generated by the second outboard motor 100S.

The controller 300 outputs command signals corresponding to the direction and amount of rotation of the steering wheel 210 to the steering actuators 164P, 164S via the ECUs 190P, 190S. The steering actuator 164P controls the steering mechanism 160P based on the received command signals to change the direction of the lower unit 130, i.e., the steering angle of the first outboard motor 100P. This changes the direction of the thrust of the first outboard motor 100P. Similarly, the steering actuator 164S controls the steering mechanism 160S based on the received command signal to change the direction of the lower unit 130, i.e., the steering angle of the second outboard motor 100S. This changes the direction of the thrust of the second outboard motor 100S. In this way, the azimuth of the boat body 10 is controlled.

For example, when the steering wheel 210 is turned to the left from the neutral position, the controller 300 outputs a command signal to the steering actuators 164P, 164S to steer the lower units 130 of the two outboard motors 100P, 100S clockwise from the 0° turning angle position. This causes the boat body 10 to turn to the left. When the steering wheel 210 is turned to the right from the neutral position, the controller 300 outputs a command signal to the steering actuators 164P, 164S to steer the lower units 130 of the two outboard motors 100P, 100S counterclockwise from the 0° turning angle position. This causes the boat body 10 to turn to the right.

When the joystick device 230 receives an operation request to switch the joystick mode from off to on (joystick mode start operation), the controller 300 receives the operation signal from the joystick sensor 250 and switches the steering mode from the normal steering mode to the joystick mode. The joystick mode start operation may be, e.g., a short press of the joystick button 240 by the steering person. When the joystick device 230 receives an operation request to switch the joystick mode from on to off (joystick mode deactivation operation), the controller 300 receives the operation signal from the joystick sensor 250 and switches the steering mode from the joystick mode to the normal steering mode. The joystick mode deactivation operation may be, e.g., a long press of the joystick button 240 by the steering person.

When the boat 1A is controlled in the joystick mode, the controller 300 receives joystick signals from the joystick sensor 250. Based on these signals, the controller 300 outputs command signals to the throttle actuators 128P, 128S, the shift actuators 152P, 152S and the steering actuators 164P, 164S via the ECUs 190P, 190S.

For example, when the joystick 232 is tilted, the controller 300 outputs command signals to the throttle actuators 128P, 128S, the shift actuators 152P, 152S, and the steering actuators 164P, 164S to move the boat body 10 in the direction in which the joystick 232 is tilted at a speed corresponding to the amount by which the joystick 232 is tilted. When the joystick 232 is twisted (rotated), the controller 300 outputs command signals to the throttle actuators 128P, 128S, the shift actuators 152P, 152S, and the steering actuators 164P, 164S to turn the boat body 10 in the direction in which the joystick 232 is twisted at an angular speed corresponding to the amount by which the joystick 232 is twisted. Based on the output command signals, the magnitude of thrust, the shift state, and the steering angle of the outboard motors 100P, 100S are controlled.

In this example embodiment, the set point mode is selected as the steering mode. The set point mode includes stay point mode, drift point mode, and fish point mode. The stay point mode (an example of the holding control) holds the position and azimuth of the boat body 10, the fish point mode holds the position of the boat body 10, and the drift point mode (an example of the holding control) holds the azimuth of the boat body 10.

When the boat 1A is controlled in the joystick mode, if the joystick device 230 accepts a press of the stay point button 241 by the steering person, the controller 300 receives the operation signal from the joystick sensor 250 and switches the steering mode to the stay point mode. When the boat 1A is controlled in the stay point mode, if the joystick device 230 accepts a press of the stay point button 241 by the steering person, the controller 300 receives the operation signal from the joystick sensor 250 and deactivates the stay point mode. The same applies to the fish point mode and the drift point mode.

For example, when the boat 1A is controlled in the stay point mode, the controller 300 receives signals from the azimuth sensor 270 and the position sensor 260 to obtain the current position and azimuth of the boat body 10, and outputs command signals to the throttle actuators 128P, 128S, the shift actuators 152P, 152S, and the steering actuators 164P, 164S to hold the boat body 10 in that position and azimuth. When the boat 1A is controlled in the fish point mode, the controller 300 receives signals from the position sensor 260 to obtain the current position of the boat body 10 and outputs command signals to the throttle actuators 128P, 128S, the shift actuators 152P, 152S, and the steering actuators 164P, 164S to hold the boat body 10 in that position. When boat 1A is controlled in the drift point mode, the controller 300 receives signals from the azimuth sensor 270 to obtain the current azimuth of the boat body 10 and outputs command signals to the throttle actuators 128P, 128S, the shift actuators 152P, 152S, and the steering actuators 164P, 164S to hold the boat body 10 in that azimuth. The magnitude of thrust, the shift state, and the steering angle of the outboard motors 100P, 100S are controlled based on the output command signals.

The procedure of controlling the outboard motors 100P, 100S by the boat control system 400A when the joystick mode start operation is executed while the boat 1A is travelling will be described with reference to FIGS. 6 to 10. As described above, when the joystick device 230 accepts the joystick mode start operation, the controller 300 switches the steering mode from the normal steering mode to the joystick mode.

Once steering in the joystick mode is started, the controller 300 determines whether the joystick 232 is in the default position (S110). This determination is based on the joystick signal received from the joystick sensor 250.

If the controller 300 determines that the joystick 232 is not in the default position, it proceeds to step S200. In step S200, the controller 300 outputs command signals to the throttle actuators 128P, 128S, the shift actuators 152P, 152S, and the steering actuators 164P, 164S so that the boat body 10 advances at a speed corresponding to the tilt or twist amount of the joystick 232 in a direction in which the joystick 232 is tilted or twisted. Based on the output command signals, the magnitude of thrust, the shift state, and the steering angle of the outboard motors 100P, 100S are controlled. After completion of step S200, the controller 300 returns to step S110 and repeats the process.

If the controller 300 determines that the joystick 232 is in the default position, it will steer the outboard motors 100P, 100S to the default steering angle (S120). The default steering angle is the steering angle at which the lower units 130 of the outboard motors 100P, 100S are in a position facing each other. In other words, the steering angle of the first outboard motor 100P is +90° and that of the second outboard motor 100S is −90° (see the left figure in FIG. 7). At this time, the outboard motors 100P, 100S are idling and the crankshaft 122 provided in both outboard motors 100P, 100S are rotating at such a low speed that the boat 1A will not start to move. With the steering angle set to the default steering angle as described above, the thrusts generated by the two outboard motors 100P, 100S cancel each other out and the boat body 10 stays in place.

After step S120 is completed, the controller 300 receives the engine output signals from the output sensors 129P, 129S, and acquires the output SP of the engine 120P and the output SS of the engine 120S (S130).

After step S130 is completed, the controller 300 determines whether the joystick 232 is in the default position (S140). If the controller 300 determines that the joystick 232 is not in the default position, it controls the magnitude and direction of the thrust of the two outboard motors 100P, 100S so that the boat body 10 advances at a speed corresponding to the operation direction and operation amount of the joystick 232, as in step S200 (S210). After completion of step S210, the controller 300 returns to step S130 to repeat the process.

If the controller 300 determines in step S140 that the joystick 232 is in the default position, it determines whether the value calculated by subtracting the output SP of the engine 120P obtained in step S130 from the output SS of the engine 120S obtained in step S130 (SS-SP) is greater than or equal to a reference value RVa (S150). The reference value RVa being a positive value and (SS-SP) being greater than or equal to the reference value RVa means that the output SS is greater than the output SP at a certain level or more.

If the controller 300 determines in step S150 that (SS-SP) is less than the reference value RVa, it determines whether the value calculated by subtracting the output SS of the engine 120S obtained in step S130 from the output SP of the engine 120P obtained in step S130 (SP-SS) is greater than or equal to the reference value RVa (S220). (SP-SS) being greater than or equal to the reference value RVa means that the output SP is greater than the output SS at a certain level or more.

If (SP-SS) is determined to be less than the reference value RVa in step S220, the controller 300 returns to step S130 and repeats the process. Here, it is rare for the output SP of engine 120P and the output SS of engine 120S to be exactly the same. Therefore, if the values of (SS-SP) and (SP-SS) are both less than the reference value RVa, that is, if the difference between the outputs SP and SS of the two engines 120P, 120S is so small that it does not cause any problems in the operation of the boat, it is determined that the outputs SP and SS of the engines 120P, 120S are effectively equal, and no special control is performed to change the outputs SP and SS. This avoids unnecessary control of the boat body 10 and allows efficient steering.

If (SS-SP) is determined to be greater than or equal to the reference value RVa in step S150, the controller 300 determines whether the throttle request for the second outboard motor 100S is zero or not (S160).

If it is determined in step S160 that the throttle request for the second outboard motor 100S is zero, the controller 300 proceeds to step S170. In step S170, the controller 300 increases the throttle opening of the engine 120P until the output SP of the engine 120P becomes equal to the output SS of the engine 120S (output adjustment process: see FIG. 7). When the output SP becomes equal to the output SS, the controller 300 terminates the output adjustment process.

As described above, when the joystick 232 is in the default position, the thrusts generated by the two outboard motors 100P, 100S cancel each other out by setting the steering angles of the two outboard motors 100P, 100S to the default steering angles. However, because of factors such as manufacturing errors, adjustment errors, deterioration over time, and differences in conditions due to warm-up operations in the outboard motors 100P, 100S, there may be cases where an unintended difference in output occurs between the two engines 120P, 120S. In such cases, the boat body 10 may turn unintentionally even though the joystick device 230 is not accepting any operation to turn the boat body 10. By controlling so that the output SP and the output SS become equal, it is possible to reduce or prevent the turning of the boat body 10 that is not intended by the steering person.

If it is determined in step S160 that the throttle request for the second outboard motor 100S is not zero, the controller 300 proceeds to step S180. In step S180, the controller 300 increases the throttle opening of the engine 120P and decreases the throttle opening of the engine 120S until the output SP of the engine 120P and the output SS of the engine 120S become equal (output adjustment process: see FIG. 8). When the output SS and the output SP become equal, the controller 300 terminates the output adjustment process. By controlling so that the output SP and the output SS become equal, it is possible to reduce or prevent the turning of the boat body 10 that is not intended by the steering person.

If (SP-SS) is determined to be greater than or equal to the reference value RVa in step S220, the controller 300 determines whether the throttle request for the first outboard motor 100P is zero (S230).

If it is determined in step S230 that the throttle request for the first outboard motor 100P is zero, the controller 300 proceeds to step S240. In step S240, the controller 300 increases the throttle opening of the engine 120S until the output SS of the engine 120S becomes equal to the output SP of the engine 120P (output adjustment process: see FIG. 9). When the output SS becomes equal to the output SP, the controller 300 terminates the output adjustment process. By controlling so that the output SP and the output SS become equal, it is possible to reduce or prevent the turning of the boat body 10 that is not intended by the steering person.

If it is determined in step S230 that the throttle request for the first outboard motor 100P is not zero, the controller 300 proceeds to step S250. In step S250, the controller 300 increases the throttle opening of the engine 120S and decreases the throttle opening of the engine 120P until the output SP of the engine 120P becomes equal to the output SS of the engine 120S (output adjustment process: see FIG. 10). When the output SS becomes equal to the output SP, the controller 300 terminates the output adjustment process. By controlling so that the output SP and the output SS become equal, it is possible to reduce or prevent the turning of the boat body 10 that is not intended by the steering person.

In addition, in steps S170, S180, S240, and S250, the controller 300 may be set to terminate the output adjustment process when the difference between the output SS and the output SP becomes small enough not to affect the steering, assuming that the output SS and the output SP to be effectively equal even if the difference between the output SS and the output SP is not completely equal.

After completion of steps S170, S180, S240, or S230, the controller 300 proceeds to step S190.

In step S190, the controller 300 determines whether the joystick mode has been deactivated. If the controller 300 receives an operation signal from the joystick sensor 250 associated with the joystick mode deactivation operation conducted by the steering person, the controller 300 determines that the joystick mode has been deactivated and switches the steering mode to the normal steering mode. If no operation signal associated with the joystick mode deactivation operation is received, the controller 300 determines that the joystick mode has not been deactivated and returns to step S130 to repeat the process.

The procedure of controlling the outboard motors 100P, 100S by the boat control system 400A when the stay point mode start operation is performed when the boat 1A described above is controlled in the joystick mode will be described with reference to FIG. 11. As described above, when the joystick device 230 accepts the stay point mode start operation, the controller 300 switches the steering mode to the stay point mode.

Once steering in the stay point mode is started, the controller 300 proceeds to step S310. In step S310, the controller 300 receives from the position sensor 260 a position signal corresponding to the position of the boat body 10 at the start of steering in the stay point mode and stores it as the target position. The controller 300 also receives from the azimuth sensor 270 an azimuth signal corresponding to the azimuth of the boat body 10 at the start of steering in the stay point mode and stores it as the target azimuth. In this specification, the azimuth of the boat body 10 is expressed as the clockwise angle of the centerline C of the boat body 10 at the time of measurement relative to the reference direction DO. The reference direction DO is shown as a dashed line in FIGS. 12 and 13. The centerline CO of the boat body 10 at the time of measurement of the target azimuth θ0 is shown as a double-dashed line.

After completion of step S310, the controller 300 steers the steering angles of the outboard motors 100P, 100S to the default steering angle (S320).

After step S320 is completed, the controller 300 obtains the position and azimuth of the boat body 10 (S330). The controller 300 receives the position signal from the position sensor 260 and stores it as the current position. The controller 300 also receives the azimuth signal from the azimuth sensor 270 and stores it as the current azimuth θ.

After step S330 is completed, the controller 300 determines whether there is a deviation between the current azimuth θ obtained in step S330 and the target azimuth θ0 (S340).

If the controller 300 determines that there is no deviation between the current azimuth θ and the target azimuth θ0 in step S340, it then determines whether there is a deviation between the current position and the target position (S400). If the controller 300 determines in step S400 that there is no deviation between the current position and the target position, it returns to S330 and repeats the process.

If the controller 300 determines in step S400 that there is a deviation between the current position and the target position, the controller 300 outputs command signals to the throttle actuators 128P, 128S, the shift actuators 152P, 152S, and the steering actuators 164P, 164S to correct the deviation. Based on the output command signals, the magnitude of thrust, the shift state, and the steering angle of the outboard motors 100P, 100S are controlled so as to correct the position of the boat body 10 (S410). After completion of step S410, the controller 300 returns to step S330 and repeats the process.

If the controller 300 determines in step S340 that there is a deviation between the current azimuth θ and the target azimuth θ0, the controller 300 determines whether the value of (current azimuth θ−target azimuth θ0) is positive or not (S350).

In this specification, the turning of the boat body 10 to the starboard side, that is, rightward (clockwise) when viewed from above, is referred to as the turning in the positive direction. The turning of the boat body 10 to the port side, that is, leftward (counterclockwise) when viewed from above, is referred to as the turning in the negative direction. When the value of (current azimuth θ−target azimuth θ0) is positive, the boat body 10 is turning in the positive (clockwise) direction since the start of steering in the stay point mode (see the left diagram in FIG. 12). When the value of (current azimuth θ−target azimuth θ0) is negative, the boat body 10 is turning in the negative (counterclockwise) direction since the start of steering in the stay point mode (see the left diagram in FIG. 13).

If the value of (current azimuth θ−target azimuth θ0) is determined to be positive in step S350, the controller 300 proceeds to step S360. In step S360, the controller 300 determines whether the throttle request for the second outboard motor 100S is zero (S360).

If the throttle request for the second outboard motor 100S is determined to be zero in step S360, the controller 300 proceeds to step S370. In step S370, the controller 300 increases the throttle opening of the engine 120P until the output SP of the engine 120P becomes equal to the output SS of the engine 120S (output adjustment process: see FIG. 12). When the output SP becomes equal to the output SS, the controller 300 terminates the output adjustment process.

As mentioned above, there are cases in which an unintended difference in output occurs between the two engines 120P, 120S, causing the boat body 10 to turn unintentionally even though the joystick device 230 does not accept the operation to turn the boat body 10. If the boat body 10 is turning in the positive (clockwise) direction, it is assumed that a left propulsion force acts on the stern because the output SS of the engine 120S is greater than the output SP of the engine 120P. By controlling so that the output SP and the output SS become equal, the thrusts generated by the two outboard motors 100P, 100S can cancel each other out to stop the turning of the boat body 10.

If it is determined in step S360 that the throttle request for the second outboard motor 100S is not zero, the controller 300 proceeds to step S380. In step S380, the controller 300 increases the throttle opening of the engine 120P and decreases the throttle opening of the engine 120S until the output SP of the engine 120P and the output SS of the engine 120S become equal (output adjustment process). When the output SS and the output SP become equal, the controller 300 terminates the output adjustment process. By controlling so that the output SP and the output SS become equal, the thrusts generated by the two outboard motors 100P, 100S cancel each other out, and the turning of the boat body 10 stops.

If the value of (current azimuth θ−target azimuth θ0) is determined to be negative in step S350, the controller 300 proceeds to step S420. In step S420, the controller 300 determines whether the throttle request for the first outboard motor 100P is zero (S420).

If the throttle request for the first outboard motor 100P is determined to be zero in step S420, the controller 300 proceeds to step S430. In step S430, the controller 300 increases the throttle opening of the engine 120S until the output SS of the engine 120S becomes equal to the output SP of the engine 120P (output adjustment process: see FIG. 13). When the output SS and the output SP become equal, the controller 300 terminates the output adjustment process.

If the boat body 10 is turning in the negative (counterclockwise) direction, it is assumed that a rightward propulsion force acts on the stern because the output SP of the engine 120P is greater than the output SS of the engine 120S. By controlling so that the output SP and the output SS become equal, the thrusts generated by the two outboard motors 100P, 100S can cancel each other out to stop the turning of the boat body 10.

If it is determined in step S420 that the throttle request for the first outboard motor 100P is not zero, the controller 300 proceeds to step S440. In step S440, the controller 300 increases the throttle opening of the engine 120S and decreases the throttle opening of the engine 120P, until the output SP of the engine 120P and the output SS of the engine 120S become equal (output adjustment process). When the output SS and the output SP become equal, the controller 300 terminates the output adjustment process. By controlling so that the output SP and the output SS become equal, the thrusts generated by the two outboard motors 100P, 100S can cancel each other out to stop the turning of the boat body 10.

In addition, in steps S370, S380, S430, and S440, the controller 300 may be set to terminate the output adjustment process when the difference between the output SS and the output SP becomes small enough not to affect the steering, assuming that the output SS and the output SP to be effectively equal even if the difference between the output SS and the output SP is not completely equal.

After completion of step S370, S380, S430, or S440, the controller 300 proceeds to step S390.

In step S390, the controller 300 determines whether the stay point mode has been deactivated. If the controller 300 receives an operation signal from the joystick sensor 250 associated with the stay point mode deactivation operation conducted by the steering person, the controller 300 determines that the stay point mode has been deactivated and switches the steering mode to the joystick steering mode. If the operation signal associated with the stay point mode deactivation operation is not received, the controller 300 determines that the stay point mode has not been deactivated and returns to step S330 to repeat the process.

As described above, the boat 1A in this example embodiment includes the boat body 10 and the boat control system 400A. The boat control system 400A includes the first outboard motor 100P and the second outboard motor 100S each steerable 180 degrees or more about a steering axis, the controller 300 configured or programmed to control the thrust and the steering angle of the first outboard motor 100P and the second outboard motor 100S, and the steering device 200 that accepts the operation request to move the boat body 10 and outputs the operation signal to the controller 300. The first outboard motor 100P includes the engine 120P that generates the power to propel the boat body 10 and the output sensor 129P that detects the output of the engine 120P and outputs the engine output signal to the controller 300. The second outboard motor 100S includes the engine 120S that generates the power to propel the boat body 10 and the output sensor 129S that detects the output of the engine 120S and outputs the engine output signal to the controller 300. The controller 300 is configured or programmed to perform, when the controller 300 determines that the outputs of the engines 120P, 120S have a difference when the steering device 200 is not accepting an operation request to turn the boat body 10, an output adjustment process to change the output of at least one of the engines 120P, 120S so as to cancel the difference in the outputs.

According to the above configuration, it is possible to reduce or prevent the unintended turning of the boat body 10 caused by the difference in the outputs of the two engines 120P, 120S, making it easier for the steering person to steer the boat as intend.

In addition, the steering device 200 includes the joystick 232 and the joystick base 234 that accepts operation requests to switch on/off the joystick mode in which the joystick 232 is able to accept operation requests to move the boat body 10, and the controller 300 to perform the output adjustment process when the joystick base 234 accepts an operation request to switch the joystick mode from off to on.

When the joystick mode is switched from off to on, there may be cases where the boat body 10 turns in a way that is not intended by the steering person. The above configuration can be suitably applied to such cases.

In addition, the controller 300 may perform the output adjustment process while performing a holding control to hold the boat body 10 in a specific orientation.

When the holding control to hold the boat body 10 in a specific orientation is being performed, there may be cases where the boat body 10 turns in a way that is not intended by the steering person. The above configuration can be suitably applied to such cases.

In addition, the output adjustment process increases the output of one of the two engines 120P, 120S having the lower output until it becomes equal to the output of the other of the two engines 120P, 120S.

With this configuration, it is possible to reduce or prevent the unintentional stopping of the outboard motors 100P, 100S.

The output adjustment process increases the output of one of the engines 120P, 120S having the lower output and decreases the output of the other one of the engines 120P, 120S.

With this configuration, the output of the two engines 120P, 120S can be quickly matched.

A second example embodiment of the present invention will be described with reference to FIGS. 14 to 17. The boat 1B of the second example embodiment further includes a third outboard motor 100C (an example of a boat propulsion device, a third boat propulsion device). The third outboard motor 100C is disposed between the first outboard motor 100P and the second outboard motor 100S at the stern of the boat body 10 (see FIG. 16). More specifically, the third outboard motor 100C is located on the centerline C of the boat body 10. The third outboard motor 100C includes a steering mechanism 160C, a steering actuator 164C, and an ECU 190C, as shown in FIG. 14. The configuration of the third outboard motor 100C is similar to that of the first outboard motor 100P, so the same elements are marked with the same symbols, and detailed descriptions are omitted. When the elements provided in the third outboard motor 100C are described separately from those provided in the first outboard motor 100P, a “C” is added to the end of the sign of the elements provided in the third outboard motor 100C.

As with the first outboard motor 100P, the third outboard motor 100C is configured to change the steering angle by rotating the lower unit 130 with respect to the upper unit 110. The controller 300 outputs command signals to the steering actuator 164C via the ECU 190C. The steering actuator 164C controls the steering mechanism 160C based on the received command signal to change the orientation of the lower unit 130, i.e., the steering angle of the outboard motor 100C. The outboard motors 100P, 100S, 100C, the steering device 200, the controller 300, the position sensor 260, and the azimuth sensor 270 are elements of the boat control system 400B.

The procedure of controlling the outboard motors 100P, 100S, 100C by the boat control system 400B when the joystick mode start operation is executed while the boat 1B is travelling will be described with reference to FIGS. 15 to 17.

Steps S510, S520, and S600 are the same as steps S110, S120, and S200 of the first example embodiment.

After step S520 is completed, the controller 300 receives an azimuth signal from the azimuth sensor 270 to obtain the azimuth of the boat body 10 (S530). In this specification, when the boat body 10 is turning in the positive (clockwise) direction, the turning speed is expressed as a positive value. When the boat body 10 is turning in the negative (counterclockwise) direction, the turning speed is expressed as a negative value.

When step S530 is completed, the controller 300 determines whether the joystick 232 is in the default position (S540). If the controller 300 determines that the joystick 232 is not in the default position, it controls the magnitude and direction of the thrust of the two outboard motors 100P, 100S so that the boat body 10 advances at a speed corresponding to the operation direction and operation amount of the joystick 232, as in step S600 (S610). After completion of step S610, the controller 300 returns to step S530 to repeat the process.

If the controller 300 determines that the joystick 232 is in the default position, it determines whether the turning speed calculated in step S530 is greater than or equal to a reference value RVb1 (S550). The reference value RVb1 being a positive value and the turning speed being greater than or equal to the reference value RVb1 means that the boat body 10 is turning at a certain speed or more in the positive (clockwise) direction

If the turning speed is determined to be less than the reference value RVb1 in step S550, the controller 300 determines whether the turning speed obtained in step S530 is less than a reference value RVb2 (S620). The reference value RVb2 being a negative value and the turning speed being less than or equal to the reference value RVb2 means that the boat body 10 is turning at a certain speed or more in a negative (counterclockwise) direction.

If it is determined in step S620 that the turning speed exceeds the reference value RVb2, the controller 300 returns to step S530 and repeats the process. Here, since the boat body 10 is affected by disturbances such as wind and tide, it is rare for the boat body 10 to reach a completely stopped status. Therefore, if the turning speed is between the two reference values RVb1 and RVb2, that is, if the turning speed is small enough to cause no problem in steering, the boat body 10 is considered not to be turning substantially and no special control is performed to correct the movement of the boat body 10. This avoids unnecessary control of the boat body 10 and makes steering more efficient.

If the turning speed is determined to be greater than or equal to the reference value RVb1 in step S550, the controller 300 determines whether the throttle request for the second outboard motor 100S is zero or not (S560).

If it is determined in step S560 that the throttle request for the second outboard motor 100S is zero, the controller 300 proceeds to step S570. In step S570, the controller 300 increases the throttle opening of the engine 120P until the output SP of the engine 120P becomes equal to the output SS of the engine 120S (output adjustment process: see FIG. 16). At this time, the third outboard motor 100C is steered in the direction in which the boat body 10 is turning, i.e., in the positive (clockwise) direction. When the output SP becomes equal to the output SS, the controller 300 terminates the output adjustment process.

By controlling so that the output SP and the output SS become equal, the thrusts generated by the two outboard motors 100P, 100S can cancel each other out to stop the turning of the boat body 10. Also, when the boat body 10 is turning in the positive (clockwise) direction, a counterclockwise water flow is generated relative to the boat body 10. The third outboard motor 100C, which is steered in the positive (clockwise) direction, acts as resistance to this water flow, thus quickly stopping the turning.

If it is determined in step S560 that the throttle request for the second outboard motor 100S is not zero, the controller 300 proceeds to step S580. In step S580, the controller 300 increases the throttle opening of the engine 120P and decreases the throttle opening of the engine 120S until the output SP of the engine 120P and the output SS of the engine 120S become equal (output adjustment process). At this time, the third outboard motor 100C is steered in the direction in which the boat body 10 is turning, i.e., in the positive (clockwise) direction. When the output SS and the output SP become equal, the controller 300 terminates the output adjustment process.

By controlling so that the output SP and output SS become equal, the turning of the boat body 10 stops. In addition, as with the above-mentioned step S570, the third outboard motor 100C, which is steered in the positive (clockwise) direction, acts as resistance to the water flow, thus quickly stopping the turning.

If the turning speed is determined to be less than or equal to the reference value RVb2 in step S550, the controller 300 determines whether the throttle request for the first outboard motor 100P is zero (S630).

If it is determined in step S630 that the throttle request for the first outboard motor 100P is zero, the controller 300 proceeds to step S640. In step S640, the controller 300 increases the throttle opening of the engine 120S until the output SS of the engine 120S becomes equal to the output SP of the engine 120P (output adjustment process: see FIG. 17). At this time, the third outboard motor 100C is steered in the direction in which the boat body 10 is turning, i.e., in the negative (counterclockwise) direction. When the output SS becomes equal to the output SP, the controller 300 terminates the output adjustment process.

By controlling so that the output SP and output SS become equal, the turning of the boat body 10 stops. Also, when the boat body 10 is turning in the negative (counterclockwise) direction, a clockwise water flow is generated relative to the boat body 10. The third outboard motor 100C, which is steered in the negative (counterclockwise) direction, acts as resistance to this water flow, thus quickly stopping the turning.

If it is determined in step S630 that the throttle request for the first outboard motor 100P is not zero, the controller 300 proceeds to step S650. In step S650, the controller 300 increases the throttle opening of the engine 120S and decreases the throttle opening of the engine 120P until the output SP of the engine 120P and the output SS of the engine 120S become equal (output adjustment process). At this time, the third outboard motor 100C is steered in the direction in which the boat body 10 is turning, i.e., in the negative (counterclockwise) direction. When the output SS and the output SP become equal, the controller 300 terminates the output adjustment process.

By controlling so that the output SP and output SS become equal, the turning of the boat body 10 stops. In addition, as with the above-mentioned step S640, the third outboard motor 100C, which is steered in the negative (counterclockwise) direction, acts as resistance to the water flow, thus quickly stopping the turning.

In addition, as in the first example embodiment, in steps S570, S580, S640, and S650, the controller 300 may be set to terminate the output adjustment process when the difference between the output SS and the output SP becomes small enough not to affect the steering, assuming that the output SS and the output SP to be effectively equal even if the difference between the output SS and the output SP is not completely equal.

The shift state of the third outboard motor 100C should be set to neutral, with no thrust being generated during the output adjustment process. This can reduce or prevent the unintended movement of the boat body 10.

After completion of step S570, S580, S640 or S630, the controller 300 proceeds to step S590.

In step S590, the controller 300 determines whether the joystick mode has been deactivated. If the controller 300 receives an operation signal from the joystick sensor 250 associated with the joystick mode deactivation operation conducted by the steering person, the controller 300 determines that the joystick mode has been deactivated and switches the steering mode to the normal steering mode. If no operation signal associated with the joystick mode deactivation operation is received, the controller 300 determines that the joystick mode has not been deactivated and returns to step S630 to repeat the process.

According to the example embodiments described above, the boat control system 400B includes the first outboard motor 100P, the second outboard motor 100S, and the third outboard motor 100C disposed between the first outboard motor 100P and the second outboard motor 100S.

When the boat 1B includes three outboard motors 100P, 100S, 100C, using the two outboard motors 100P, 100S on the outside in the output adjustment process can balance the position of the two outboard motors 100P, 100S used for the output adjustment process, thus efficiently reducing or preventing the turning of the boat body 10.

In addition, the boat control system 400B further includes the azimuth sensor 270 that detects a turning of the boat body 10 and outputs an azimuth signal to the controller 300, and the controller 300 steers the third outboard motor 100C in the direction in which the boat body 10 is turning in the output adjustment process. With this configuration, the third outboard motor 100C acts as resistance to the water flow generated by the turning of the boat body 10, thus suppressing the turning more effectively.

The technologies disclosed herein are not limited to the above-described example embodiments and may be modified in various ways without departing from the gist of the present invention, including the following modifications.

In the above example embodiments, the outboard motors 100P, 100S, 100C are outboard motors driven by an engine, but the outboard motors can also be electric outboard motors driven by a motor.

In the first example embodiment, examples are shown in which the output adjustment process is executed when the difference between the outputs SP, SS of the two engines 120P, 120S is determined to be a certain level or more in the control by the boat control system 400A when the joystick mode start operation is performed, and the output adjustment process is executed when the turning speed is determined to be a certain level or more in the control by the boat control system 400A during control in the stay point mode. However, the output adjustment process may be executed when the turning speed is determined to be a certain level or more in the control by the boat control system when the joystick mode start operation is performed, and the output adjustment process may be executed when the difference between the outputs of the two drive sources is determined to be a certain level or more in the control by the boat control system during control in the stay point mode. The same applies when the boat is equipped with three or more boat propulsion devices.

In the first example embodiment, an example is shown in which the output adjustment process is executed when performing a control in the stay point mode as a holding control, but for example, the output adjustment process may be executed when performing a control in the drift point mode as a holding control.

In the second example embodiment, the boat 1B includes three outboard motors 100P, 100S, 100C, but the boat may include four or more outboard motors. In that case, any of the outboard motors may be used in the output adjustment process, but it is preferable to use the two outboard motors at the ends as the first and second outboard motors used in the output adjustment process.

In the second example embodiment, the third outboard motor 100C is steered in addition to the first outboard motor 100P and the second outboard motor 100S, but the third outboard motor does not have to be steered in the output adjustment process for a boat having three or more outboard motors.

In the second example embodiment, an example is shown in which the third outboard motor 100C is steered in the output adjustment process when a control is being performed in the joystick mode, but the third outboard motor may be steered in the output adjustment process during a holding control, such as a control in the stay point mode.

In the above example embodiments, the boat propulsion devices are outboard motors 100P, 100S, 100C, but the boat propulsion devices can be inboard motors, inboard/outboard motors, or jet propellers.

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.

BOAT CONTROL SYSTEM AND BOAT

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CPC

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