Navigation assistance device, navigation assistance method, and program

A navigation assistance method executed by a computer for obtaining an obstacle zone by target from a relationship between an own ship and a target ship, comprising:

• acquiring a margin indicating a passing distance set as an allowance by a degree;
• calculating at least one of a first obstacle zone by target or a second obstacle zone by target as the obstacle zone by target;
• and
• outputting at least one of the first obstacle zone by target or the second obstacle zone by target,
• wherein in a case of calculating the first obstacle zone by target, the method comprises:
• obtaining a first margin position which is a position separated from a bow position of the target ship in a target occupied space set with reference to a position of the target ship by a distance determined according to the margin in a direction of a target ship course;
• obtaining a first bow side collision course based on a position determined according to a motion vector of the target ship with reference to the first margin position, obtaining a first intersection point which is an intersection point between the first bow side collision course and a straight line in the direction of the target ship course with the first margin position as a base point;
• obtaining a first stern side collision course based on a position determined according to the motion vector with reference to a stern contact point on a tangent line from a position of the own ship to a stern side of the target occupied space, obtaining a second intersection point which is an intersection point between the first stern side collision course and a straight line in the direction of the target ship course with the stern contact point as a base point;
• and
• calculating a line segment connecting the first intersection point and the second intersection point as the first obstacle zone by target, and
• in a case of calculating the second obstacle zone by target, the method comprises:
• obtaining a second margin position which is a position separated from a stern position of the target ship in the target occupied space set with reference to a position of the target ship by a distance determined according to the margin in the opposite direction to the direction of the target ship course;
• obtaining a second stern side collision course based on a position determined according to the motion vector with reference to the second margin position, obtaining a third intersection point which is an intersection point between the second stern side collision course and a straight line in the direction of the target ship course with the second margin position as a base point;
• obtaining a second bow side collision course based on a position determined according to the motion vector with reference to a bow contact point on a tangent line from a position of the own ship to a bow side of the target occupied space, obtaining a fourth intersection point which is an intersection point between the second bow side collision course and a straight line in the direction of the target ship course with the bow contact point as a base point;
• and
• calculating a line segment connecting the third intersection point and the fourth intersection point as the second obstacle zone by target.

A non-transitory computer-readable medium storing a program causing a computer to

• acquire a margin indicating a passing distance set as an allowance by a degree;
• calculate at least one of a first obstacle zone by target or a second obstacle zone by target as the obstacle zone by target;
• and
• output at least one of the first obstacle zone by target or the second obstacle zone by target,
• wherein in a case of calculating the first obstacle zone by target, the program causes the computer to:
• obtain a first margin position which is a position separated from a bow position a target ship in a target occupied space set with reference to a position of the target ship by a distance determined according to the margin in a direction of a target ship course;
• obtain a first bow side collision course based on a position determined according to a motion vector of the target ship with reference to the first margin position, obtain a first intersection point which is an intersection point between the first bow side collision course and a straight line in the direction of the target ship course with the first margin position as a base point;
• obtain a first stern side collision course based on a position determined according to the motion vector with reference to a stern contact point on a tangent line from a position of the own ship to a stern side of the target occupied space, obtain a second intersection point which is an intersection point between the first stern side collision course and a straight line in the direction of the target ship course with the stern contact point as a base point;
• and
• calculate a line segment connecting the first intersection point and the second intersection point as the first obstacle zone by target, and
• in a case of calculating the second obstacle zone by target, the program causes the computer to:
• obtain a second margin position which is a position separated from a stern position of the target ship in the target occupied space set with reference to a position of the target ship by a distance determined according to the margin in the opposite direction to the direction of the target ship course;
• obtain a second stern side collision course based on a position determined according to the motion vector with reference to the second margin position, obtain a third intersection point which is an intersection point between the second stern side collision course and a straight line in the direction of the target ship course with the second margin position as a base point;
• obtain a second bow side collision course based on a position determined according to the motion vector with reference to a bow contact point on a tangent line from a position of the own ship to a bow side of the target occupied space, obtain a fourth intersection point which is an intersection point between the second bow side collision course and a straight line in the direction of the target ship course with the bow contact point as a base point;
• and
• calculate a line segment connecting the third intersection point and the fourth intersection point as the second obstacle zone by target.