Navigation planning system and navigation planning method

1 . A navigation planning system, comprising:

processing circuitry configured 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 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 the collision risk 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 being determined,

wherein the movable body is oriented in a reference direction at an end point of the evasion route.

2 . The navigation planning system according to claim 1 , wherein the reference direction at the end point of the evasion route is parallel to a direction of the movable body at a position where the movable body begins to deviate from the planned route, or parallel to a direction at a selected point on the planned route.

3 . The navigation planning system according to claim 1 , wherein the reference direction at the end point of the evasion route is toward a destination from a position where the movable body begins to evade, or toward a selected point on the planned route from the position where the movable body begins to evade.

4 . The navigation planning system according to claim 1 , wherein the processing circuitry is further configured to:

generate a plurality of potential evasion route patterns, different from the planned route, between an evasion starting point on the planned route and an end point of the planned route;

evaluate a collision risk of each said potential evasion route pattern from the plurality of potential evasion route patterns; and

select a potential evasion route pattern from the plurality of potential evasion route patterns based on the collision risks,

wherein the selected potential evasion route pattern is the evasion route for the movable body.

5 . The navigation planning system according to claim 4 , wherein the selected potential evasion route pattern has a minimum collision risk of the collision risks.

6 . The navigation planning system according to claim 1 , wherein the processing circuitry is further configured to:

generate a plurality of potential evasion route patterns, different from the planned route, between an evasion starting point on the planned route and an end point of the planned route;

evaluate a collision risk of each said potential evasion route pattern from the plurality of potential evasion route patterns;

calculate a distance between the evasion starting point and the end point along each said potential evasion route pattern from the plurality of potential evasion route patterns; and

select a potential evasion route pattern from the plurality of potential evasion route patterns based on the collision risks and the distance,

wherein the selected potential evasion route pattern is the evasion route for the movable body.

7 . The navigation planning system according to claim 1 , wherein the processing circuitry is further configured to:

extract the maximum collision risk obstacle corresponding to a maximum collision risk value from the plurality of obstacles including each said potential evasion route pattern;

select a plurality of the potential evasion route patterns, wherein each said maximum collision risk value of the maximum collision risk obstacle is below a collision risk threshold value; and

select a potential evasion route pattern from the selected plurality of potential evasion route patterns based on the collision risk and the distance.

8 . The navigation planning system according to claim 1 ,

wherein the congestion risk value indicates a degree of simultaneous approach regarding the plurality of obstacles based on the collision risk value between the movable body and each of the one or more obstacles from the plurality of obstacles, and

wherein the processing circuitry is further configured to:

determine the necessity of evasion based on the collision risk value and the congestion risk value.

9 . The navigation planning system according to claim 8 , wherein the processing circuitry is further configured to:

calculate the congestion risk value based on a logical sum of a plurality of collision risk values associated with the plurality of obstacles.

10 . The navigation planning system according to claim 8 , wherein the processing circuitry is further configured to:

generate a plurality of potential evasion route patterns, different from the planned route between an evasion starting point on the planned route and an end point of the planned route;

evaluate a collision risk of each said potential evasion route pattern from the plurality of potential evasion route patterns;

evaluate the congestion risk of each said potential evasion route pattern from the plurality of potential evasion route patterns; and

select a potential evasion route pattern from the plurality of potential evasion route patterns based on the collision risks and the congestion risk.

11 . The navigation planning system according to claim 10 , wherein the processing circuitry is further configured to:

extract the maximum collision risk obstacle corresponding to a maximum collision risk value from the plurality of obstacles including each said potential evasion route pattern;

select a plurality of the potential evasion route patterns, wherein each said maximum collision risk value of the maximum collision risk obstacle is below a collision risk threshold value; and

select a potential evasion route pattern from the selected plurality of potential evasion route patterns based on the collision risk and the congestion risk.

12 . The navigation planning system according to claim 10 , wherein the processing circuitry is further configured to:

extract the maximum collision risk obstacle corresponding to a maximum collision risk value from the plurality of obstacles including each said potential evasion route pattern; and

select a plurality of the potential evasion route patterns, wherein each said maximum collision risk value of the maximum collision risk obstacle is below a collision risk threshold value;

calculate the distance between the evasion starting point and the end point along each said potential evasion route; and

select a potential evasion route pattern from the plurality of potential evasion route patterns based on the collision risks, the congestion risk, and the distance,

wherein the selected potential evasion route pattern is the evasion route for the movable body.

13 . The navigation planning system according to claim 8 , wherein the processing circuitry is configured to:

release a restriction on the direction of the end point of the evasion route and set a new evasion route having the collision risk value below a collision risk threshold value and the congestion risk value below a congestion risk threshold value, under a condition where there is no evasion route having the collision risk value below the collision risk threshold value and the congestion risk value below the congestion risk threshold value.

14 . The navigation planning system according to claim 8 , wherein the processing circuitry is configured to:

select the evasion route from the plurality of potential evasion route patterns in which a distance traveled by the movable body is minimum among the plurality of potential evasion route patterns having the collision risk value below the collision risk threshold value and the congestion risk value below the congestion risk threshold value.

15 . The navigation planning system according to claim 1 , wherein the processing circuitry is configured to:

periodically acquire the movable body information;

periodically acquire the obstacle information;

periodically calculate the collision risk value;

periodically determine the necessity of the evasion; and

periodically set the evasion route in response to the necessity of the evasion being determined.

16 . 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.

17 . The navigation planning method according to claim 16 , wherein the reference direction at the end point of the evasion route is parallel to a direction of the movable body at a position where the movable body begins to deviate from the planned route, parallel to a direction at a selected point on the planned route, toward a destination from the position where the movable body begins to evade, or toward the selected point on the planned route from the position where the movable body begins to evade.

18 . The navigation planning method according to claim 16 , further comprising:

generating a plurality of potential evasion route patterns, different from the planned route, between an evasion starting point on the planned route and an end point out of the planned route;

evaluating a collision risk of each said potential evasion route pattern from the plurality of potential evasion route patterns; and

selecting a potential evasion route pattern from the plurality of potential evasion route patterns based on the collision risks,

wherein the selected potential evasion route pattern is the evasion route for the movable body.

19 . 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.