Navigation planning system and navigation planning method

A navigation planning method, comprising:

• acquiring a planned route indicating a navigation planning route of a movable body on a water;
• acquiring movable body information including a position, a moving direction, and a speed of the movable body;
• acquiring obstacle information including a position, a moving direction, and a speed of a plurality of obstacles located in a surrounding area of the movable body;
• calculating a collision risk value indicating a risk level of collision between the movable body and one or more of the plurality of obstacles based on the movable body information and the obstacle information for the one or more of the plurality of obstacles;
• determining a necessity of evasion based on the collision risk value;
• calculating a congestion risk value based on a plurality of collision risk values associated with the plurality of obstacles excluding a maximum collision risk value and including a second largest collision risk value among the plurality of collision risk values;
• and
• setting an evasion route different from the planned route in response to the necessity of the evasion being determined,
• wherein the movable body is oriented in a reference direction at an end point of the evasion route.

A non-transitory computer readable medium having stored thereon computer-executable instructions which, when executed by a computer, cause the computer to:

• acquire a planned route indicating a navigation planning route of a movable body on a water;
• acquire movable body information including a position, a moving direction, and a speed of the movable body;
• acquire obstacle information including a position, a moving direction, and a speed of a plurality of obstacles located in a surrounding area of the movable body;
• calculate a collision risk value indicating a risk level of collision between the movable body and one or more of the plurality of obstacles from the plurality of obstacles based on the movable body information and the obstacle information for the one or more of the plurality of obstacles;
• determine a necessity of evasion based on comparing the collision risk value with a threshold value;
• calculate a congestion risk value based on a plurality of collision risk values associated with the plurality of obstacles excluding a maximum collision risk value and including a second largest collision risk value among the plurality of collision risk values;
• and
• set an evasion route different from the planned route in response to the necessity of the evasion having been determined,
• wherein the movable body is oriented in a reference direction at an end point of the evasion route.