Boat and control method for same

1. A boat comprising: a boat body; a propulsion device disposed in the boat body and that generates a propulsion force to move the boat body; a positional sensor that detects a current position of the boat body and outputs position information indicating the current position; and a controller configured or programmed to: receive the position information; determine a target position of the boat body; calculate a distance between the current position and the target position; determine a target speed of the boat body to reach the target position in accordance with the distance; calculate a force of an outside disturbance, and determine a target propulsion force of the propulsion device based on the force of the outside disturbance and the target speed; and generate an instruction signal to control the propulsion device to produce the target propulsion force; determine, as the target speed, a first target value of a speed in a front-back direction of the boat body when the distance is greater than a predetermined distance threshold; and determine, as the target speed, a second target value of the speed in the front- back direction of the boat body and a target value of a speed in a left-right direction of the boat body when the distance is equal to or less than the predetermined distance threshold.

2. The boat according to claim 1 , wherein

the positional sensor detects a current bearing of the boat body, and the position information includes the current bearing of the boat body; and

the controller is configured or programmed to:

determine a target bearing from the target position;

calculate a bearing difference between the current bearing and the target bearing;

determine a target angular speed and the target speed of the boat body in accordance with the bearing difference and the distance; and

determine the target propulsion force based on the force of the outside disturbance, the target speed, and the target angular speed.

3. The boat according to claim 2 , further comprising:

a steering actuator that changes a steering angle of the boat body; wherein

the controller is configured or programmed to:

determine a target steering angle of the boat body based on the force of the outside disturbance, the target speed, and the target angular speed; and

generate an instruction signal to control the steering actuator so that the steering angle of the boat body becomes the target steering angle.

4. The boat according to claim 3 , wherein the controller is configured or programmed to calculate the force of the outside disturbance based on a motion equation of the boat body, and an actual speed, an actual angular speed, an actual propulsion force, and an actual steering angle of the boat body.

5. The boat according to claim 1 , further comprising:

a display that displays an environment map indicating a shape of a shore arrival location; and

an input that accepts an input of the shore arrival location on the environment map; wherein

the controller is configured or programmed to determine, as the target position, the shore arrival location based on the input in the input.

6. The boat according to claim 1 , further comprising:

a receiver that receives trailer position information transmitted from a trailer and indicates a current position of the trailer, or a sensor that detects the current position of the trailer and obtains the trailer position information; wherein the controller is configured or programmed to determine the current position of the trailer as the target position.

7. The boat according to claim 1 , wherein the controller is configured or programmed to determine the target propulsion force based on a Lyapunov theory of stability from a motion equation of the boat body.

8. A control method for a boat comprising: receiving position information indicating a current position of a boat body; determining a target position of the boat body; calculating a distance between the current position and the target position; determining a target speed of the boat body to reach the target position in accordance with the distance; calculating a force of an outside disturbance; determining a target propulsion force of a propulsion device based on the force of the outside disturbance and the target speed; and generating an instruction signal to control the propulsion device mounted in the boat body to produce the target propulsion force; wherein a first target value of a speed in a front-back direction of the boat body is determined as the target speed when the distance is greater than a predetermined distance threshold; and a second target value of the speed in the front-back direction of the boat body and a target value of a speed in a left-right direction of the boat body are determined as the target speed when the distance is equal to or less than the predetermined distance threshold.

9. The control method for a boat according to claim 8 , wherein the position information includes a current bearing of the boat body; and

the control method further comprises:

determining a target bearing from the target position; and

calculating a bearing difference between the current bearing and the target bearing; wherein

a target angular speed and the target speed of the boat body are determined in accordance with the bearing difference and the distance; and

the target propulsion force is determined based on the force of the outside disturbance, the target speed, and the target angular speed.

10. The control method for a boat according to claim 9 , further comprising:

determining a target steering angle of the boat body based on the force of the outside disturbance, the target speed, and the target angular speed; and

generating an instruction signal to control a steering actuator mounted in the boat body so that the steering angle of the boat body becomes the target steering angle.

11. The control method for a boat according to claim 10 , wherein the force of the outside disturbance is calculated based on a motion equation of the boat body, and an actual speed, an actual angular speed, an actual propulsion force, and an actual steering angle of the boat body.

12. The control method for a boat according to claim 8 , further comprising:

displaying an environment map indicating a shape of a shore arrival location; and

accepting an input of the shore arrival location on the environment map; wherein the shore arrival location input to the input is determined as the target position.

13. The control method for a boat according to claim 8 , further comprising:

obtaining trailer position information indicating a current position of a trailer; wherein

the current position of the trailer is determined as the target position.

14. The control method for a boat according to claim 8 , wherein the target propulsion force is determined based on a Lyapunov theory of stability from a motion equation of the boat body.